The Knee - Articles in Press

Posterior cruciate substituting versus posterior cruciate retaining total knee arthroplasty prostheses: A meta-analysis - Corrected Proof

Shi-xing Luo, J.M. Zhao, Wei Su, Xiao-feng Li, Gui-fu Dong — 2012-02-03

Abstract: Purpose: The arguments about whether posterior-substituting prostheses or cruciate-retaining prostheses are superior to the other after total knee arthroplasty never stop. This meta-analysis was conducted to evaluate the clinical effects of these two different designs.Methods: The study was performed according to the guidelines described in the Cochrane handbook for systematic reviews of interventions. Methodological features were collected and extracted by two reviewers independently.Results: Nine randomized controlled trials with 1261 knees were eligible for pooled analysis. The meta-analysis demonstrated there were no statistical differences in the Knee Society Score, Hospital for Special Surgery, Western Ontario and McMaster Universities index, tibial component alignment, femoral component alignment, tibial posterior slope, joint line, and incidence of complications with short-to medium-term follow-up (p>0.01). Statistically difference in postoperative range of motion (WMD: 4.34°, 95% CI: 3.18° to 5.50°) in favor of PS prostheses was found between groups (p<0.01).Conclusion: The findings indicate there were no significant statistical differences in knee scores, radiological outcomes, and complications between the two types of implants. Statistically significant difference in postoperative ROM was found between the two groups, but no clinical difference.

Minocycline reduces articular cartilage damage following osteochondral injury - Corrected Proof

Akira Yamamoto, Adam P. Warren, Hubert T. Kim — 2012-02-02

Abstract: Introduction: Secondary injury pathways activated after chondral and osteochondral injury represent a potential target for therapies designed to minimize articular cartilage loss. The primary objective of this study was to test the potential chondroprotective effects of intra-articular minocycline following osteochondral injury.Methods: In vitro experiments were first performed with rabbit femoral condyles explants using an osteochondral drill injury model. Data from these in vitro experiments showed that minocycline at concentrations of 10–1000nM decreased chondrocyte apoptosis in a dose-dependent manner. In vivo experiments were then conducted using the same injury model, studying the effects of intra-articular minocycline on chondrocyte apoptosis, chondrocyte cell number, and cartilage thickness.Results: Four days after injury, minocycline delivered daily directly into the rabbit knee joints decreased acute chondrocyte apoptosis by 56% compared to controls. Analysis performed six weeks after injury demonstrated superior chondrocyte cell number, cartilage thickness, and cartilage repair in animals receiving short-term (one-week) minocycline treatment compared to controls.Conclusions: These data support a therapeutic approach utilizing drugs like minocycline for the acute treatment of osteochondral injuries.

Prospective study of gait function before and 2years after total knee arthroplasty - Corrected Proof

Inès A. Kramers-de Quervain, Stéphane Kämpfen, Urs Munzinger, Anne F. Mannion — 2012-02-02

Abstract: Purpose: To perform a prospective evaluation of gait before and 2years after total knee arthroplasty (TKA) and examine the influence of comorbidity and other joint problems on gait characteristics and their improvement after TKA.Methods: One hundred and eleven patients scheduled for TKA took part (34 men, 65±10y; 77 women, age 68±9y). Gait velocity, cadence, and ground reaction force parameters were measured before and 2years after surgery. Patients completed a questionnaire to rate their pain and other joint problems. Comorbidity was measured with the American Society of Anaesthesiologists (ASA) score.Results: Two years after TKA there were significant improvements (each p<0.05) in gait velocity and cadence and most of the ground reaction parameters, though forces during loading/unloading remained lower for the operated leg than for the contralateral leg. Higher comorbidity and other painful joints of the lower extremities/spine had a consistent, negative influence (p<0.05) on the absolute values achieved for the gait parameters although their improvement compared with baseline was independent of these factors.Conclusions: Comorbidity and other joint problems negatively influenced gait performance. These confounders should be taken into account when setting realistic patient expectations and when interpreting the success of TKA in the individual patient. Improvement in gait is however still possible, within the bounds of concomitant comorbidity.

A randomized, double-blind, dose-ranging study comparing wound infiltration of DepoFoam bupivacaine, an extended-release liposomal bupivacaine, to bupivacaine HCl for postsurgical analgesia in total knee arthroplasty - Corrected Proof

Kenneth Bramlett, Erol Onel, Eugene R. Viscusi, Kevin Jones — 2012-01-30

Abstract: Introduction: DepoFoam bupivacaine is a novel liposomal formulation of bupivacaine designed to provide prolonged postsurgical analgesia. This dose-ranging study evaluated extent and duration of analgesia following administration of DepoFoam bupivacaine in patients undergoing total knee arthroplasty (TKA).Methods: Efficacy, safety, and pharmacokinetics of DepoFoam bupivacaine doses of 133, 266, 399, or 532mg were compared with bupivacaine HCl (150mg) with epinephrine given as single injections via wound infiltration in TKA patients (N=138). Primary efficacy measure was AUC of pain intensity scores assessed by numeric rating scale with activity (NRS-A) through Day 4 postsurgery. Other assessments included pain intensity at rest (NRS-R), postsurgical opioid consumption, and safety, among others.Results: Mean AUC of NRS-A scores through Day 4 were 20.7, 19.5, 18.8, and 19.1 for the 133-mg, 266-mg, 399-mg, and 532-mg DepoFoam bupivacaine groups vs 20.4 for bupivacaine HCl. With DepoFoam bupivacaine 532-mg, differences in NRS-R scores reached statistical significance (P<0.05) vs bupivacaine HCl on Days 1 and 5 and mean AUC NRS-R scores were significantly lower through Days 2–5; a dose–response trend was demonstrated. Mean rating for blinded care provider's satisfaction with analgesia was significantly higher for DepoFoam bupivacaine 532mg vs bupivacaine HCl (P≤0.05). Other efficacy measures showed no statistically significant differences.Conclusion: Exposure to bupivacaine increased in a dose-related manner, as reflected by mean and maximum plasma bupivacaine concentrations, and AUC0−∞. Treatment with DepoFoam bupivacaine 532mg was associated with statistically significantly greater analgesia while patients were at rest after surgery compared with bupivacaine HCl.

Antagonist muscle moment is increased in ACL deficient subjects during maximal dynamic knee extension - Corrected Proof

2012-01-30

Abstract: Introduction: Coactivation of the hamstring muscles during dynamic knee extension may compensate for increased knee joint laxity in anterior cruciate ligament (ACL) deficient subjects. This study examined if antagonist muscle coactivation during maximal dynamic knee extension was elevated in subjects with anterior cruciate ligament (ACL) deficiency compared to age-matched healthy controls.Methods: Electromyography (EMG) and net knee joint moments were recorded during maximal concentric quadriceps and eccentric hamstring contractions, performed in an isokinetic dynamometer (ROM: 90–10°, angular speed: 30°/s). Hamstring antagonist EMG recorded during concentric quadriceps contraction was converted into antagonist moment based on the EMG–moment relationship observed during eccentric agonist contractions.Results: The magnitude of antagonist hamstring EMG was 65.5% higher in ACL deficient subjects compared to healthy controls (p<0.05). Likewise, antagonist hamstring moment expressed in percentage of the measured net extension moment was elevated in ACL deficient subjects (56±8 to 30±6%) compared to controls (36±5 to 19±2%) at 20–50° of knee flexion (0°=full extension) (p<0.05).Discussion: The results showed a marked increase in hamstring coactivation towards more extended joint positions. Notably, this progressive rise in coactivation was greater in ACL deficient subjects, which may reflect a compensatory strategy to provide stability to the knee joint in the anterior–posterior plane during isolated knee extension. The present study encourages further investigations of hamstring coactivation in ACL deficient subjects.

A new press-fit stem concept to reduce the risk of end-of-stem pain at revision TKA: A pre-clinical study - Corrected Proof

A. Completo, F. Fonseca, J.A. Simões, A. Ramos, C. Relvas — 2012-01-27

Abstract: Purpose: Revision total knee arthroplasty presents numerous technical challenges, with lower patient outcomes compared with those obtained in primary surgery. Extended stems have been used in revision total knee arthroplasty to improve component alignment and fixation. Hybrid fixation with cemented tibial tray and press-fit stem has shown good results. One of the disadvantages of this technique is pain related to the presence of a cementless diaphyseal engaging stem, often designated as end-of-stem pain. Patients with this pain have reported a decrease in overall satisfaction, as well as demonstrate a lower clinical outcome score. Clinical findings suggest that stem material and design are important factors in the development of end-of-stem pain. Therefore, a question can be raised: can a novel press-fit stem concept minimize bone strain changes at the stem tip? The hypothesis here considered lies upon the fact, that if periosteal cortex strain changes are minimized at the stem tip comparatively to the intact situation, the risk of end-of-stem pain might be minimized.Scope: This pre-clinical study was accomplished using synthetic tibiae to experimentally predict the periosteal cortex strains at the proximal and stem tip regions, with a commercial press-fit stem and a new stem concept.Conclusions: The results demonstrated that the new stem concept has the ability to minimize strain changes induced by the stem tip at the distal periosteal cortex and consequently, at the periosteal layer of bone tissue, which is highly pain sensitive, probably contributing to the reduction of the risk of end-of-stem pain.Level of evidence: V

Evaluating rotational kinematics of the knee in ACL reconstructed patients using 3.0Tesla magnetic resonance imaging - Corrected Proof

Abbas Kothari, Bryan Haughom, Brian Feeley, Xiaojuan Li, C. Benjamin Ma — 2012-01-24

Abstract: Introduction: Injury to the anterior cruciate ligament (ACL) is common. While prior studies have shown that surgical reconstruction of the ACL can restore anterior–posterior kinematics, ACL-injured and reconstructed knees have been shown to have significant differences in tibial rotation when compared to uninjured knees. Our laboratory has developed an MR compatible rotational loading device to objectively quantify rotational stability of the knee following ACL injuries and reconstructions. Previous work from our group demonstrated a significant increase in total tibial rotation following ACL injuries. The current study is a prospective study on the same cohort of patients who have now undergone ACL reconstruction. We hypothesize that ACL reconstructed knees will have less tibial rotation relative to the pre-operative ACL deficient condition. We also hypothesize that ACL reconstructed knees will have greater rotational laxity when compared to healthy contralateral knees.Methods: Patients. Six of the ACL injured patients from our initial study who had subsequently undergone ACL reconstruction were evaluated 8.1±2.9 months after surgery. All patients underwent single-bundle ACL reconstruction using anteromedial portal drilling of the femoral tunnel with identical post-operative regimens.Magnetic Resonance (MR) Imaging. Patients were placed in a supine position in the MR scanner on a custom-built loading device. Once secured in the scanner bore, an internal/external torque was applied to the foot. The tibiae were semi-automatically segmented with in-house software. Tibial rotation comparisons were made within subjects (i.e. side-to-side comparison between reconstructed and contralateral knees) and differences were explored using paired sample t-tests with significance set at p=0.05.Results: Regarding tibial rotation, in the ACL deficient state, these patients experienced an average of 5.9±4.1° difference in tibial rotation between their ACL deficient and contralateral knees. However, there was a −0.2±6.1° difference in tibial rotation of the ACL reconstructed knee when compared to the contralateral uninjured knee. Regarding tibial translation, ACL deficient patients showed a difference of 0.75±1.4mm of anterior tibial translation between injured and healthy knees. After ACL reconstruction, there was a 0.2±1.1mm difference in coupled anterior tibial translation of the ACL reconstructed knee compared to the contralateral knee. No significant differences in contact area between the two time points could be discerned.Discussion: The objective of our study was to assess the rotational laxity present in ACL reconstructed knees using a previously validated MRI-compatible rotational loading device. Our study demonstrated that ACL reconstruction can restore rotational laxity under load. This may speak to the benefit of an anteromedial drilling technique, which allows for a more horizontal and anatomically appropriate graft position.

Clinical results of open synovectomy for treatment of diffuse pigmented villonodular synovitis of the knee: Case series and review of literature - Corrected Proof

2012-01-20

Abstract: Purpose: The purpose of current study was to evaluate recurrence of diffuse pigmented villonodular synovitis (DPVNS), functional outcome, and osteoarthritic change of the knee.Methods: Seventeen cases in 17 patients who had DPVNS of the knee that had not been previously treated were reviewed to determine the outcomes of surgical treatment. There were 10 males and 7 females, and their average age was 33.2 years (SD 17.2) at the time of first operation. Magnetic resonance imaging (MRI) was performed preoperatively to estimate the extent of the lesion. All patients were operated with open synovectomy. The mean postoperative follow-up period was 65.4 months (range 10.2 to 145.8; SD 48.3).Results: Two of 17 patients had posterior extra-articular lesions and recurrence. Two knees slightly reduced range of motion (from 145 to 130, from 145 to 125) and four knees progressed osteoarthritic changes, but overall postoperative results were satisfactory.Conclusions: Because DPVNS sometimes exists out of knee joint, we should adequately check the location of the lesions using preoperative MRI, and synovectomy should be performed throughout knee joint including extra-articular lesion, especially around ligaments, meniscus, and suprapatellar was completely resected.Level of Evidence: Therapeutic Level IV.

Robotic-assisted unicompartmental knee arthroplasty in a patient with combined medial compartment arthritis and subchondral defect of the medial femoral condyle - Corrected Proof

2012-01-20

Abstract: Subchondral defects, or severe osteoarthritic changes, of the medial compartment may complicate component positioning and require proper planning and exact placement to ensure adequate and stable fixation and proper postoperative kinematics. This is a case report on our experience with a CT-based robotic tactile guidance system for unicompartmental knee replacement in a patient with combined medial compartment degenerative joint disease and subchondral defect of the medial femoral condyle. Using the TGS in this case, an exact burring process of the femoral cavity adjacent to the subchondral defect resulted in accurate burring of the cavity depth and width, while preservation of the surrounding supporting bony boundary was possible.

Fungal osteomyelitis after arthroscopic anterior cruciate ligament reconstruction: a case report with review of the literature - Corrected Proof

Lei Sun, Lei Zhang, Kai Wang, Wei Wang, Min Tian — 2012-01-03

Summary: Fungal osteomyelitis is a very rare complication after anterior cruciate ligament (ACL) reconstruction associated with catastrophic consequences. Herein, we present a case of such disastrous complication after ACL reconstruction. A 23-year-old man developed fever, swelling and pain of the affected knee from 18days after arthroscopic ACL reconstruction. Therefore, he underwent arthroscopic debridement, removal of the graft and internal fixators, irrigation and suction drainage, successively. Negative results for serial bacterial cultures and smear examinations are obtained. However, computer tomography and X-ray examination showed massive bone destruction at 48days after ACL reconstruction. As the first open debridement was performed at 50days after ACL reconstruction, fungal infection was diagnosed based on finding Aspergillus hyphae in pathologic examination of the debrided bone sample. After the final debridement, a 12-cm bone loss in the distal femur was treated by Ilizarov's bone transport. The patient got solid arthrodesis of the affected knee without clinical infection at a year after the initial operation. In addition, a review of the literature regarding case reports of fungal osteomyelitis after ACL reconstruction is presented.

Effect of tibial component varus on wear in total knee arthroplasty - Corrected Proof

2011-12-29

Abstract: Introduction: Malalignment can result in poor clinical outcomes and increased wear. However, component malalignment can occur even when overall limb mechanical axis is within the normal anatomic range. We studied the effect of component malalignment in the presence of acceptable knee alignment in knee arthroplasty.Methods: Sixteen tibial inserts retrieved at revision surgery were laser-mapped to measure wear. Average implantation duration was 7.7years (range, 1 to 13). Early (postprimary) and final (prerevision) radiographs were analyzed for overall alignment (limb, femoral and tibial components) and osteolysis.Results: The tibial components were initially aligned in a mean of 1.3±1.7º varus (range, –1.5 to 4.5°), which increased to 3.2±2.9º (range, –2.0 to 8.0°) at the time of revision (p=0.05). Tibial components initially placed in greater than 3° varus were associated with almost twice the volumetric penetration rate. Anatomic knee angles were 5.4±0.9º valgus (range, 4.0 to 7.0°) in the post-primary radiographs and decreased in prerevision radiographs to 3.8±2.6º (range, –1.0 to 7.5°), (p=0.04).Discussion: Tibial varus was associated with increased medial compartment wear and total wear, thus affecting osteolysis in addition to local destruction of the bearing surface. Varus malalignment as low as 3° may result in accelerated wear, even if overall limb alignment is nearly ideal. These results indicate that tibial component alignment is an important factor associated with tibial tray subsidence and polyethylene wear even when limb alignment is neutral.

Contact pressure on ACL hamstring grafts in the bone tunnel with interference screw fixation — Dynamic adaptation under load - Corrected Proof

2011-12-26

Abstract: Introduction: Interference screws used in fixation of anterior cruciate ligament (ACL) hamstring grafts create mechanical hold by forcing the graft into frictional contact with the bone tunnel. We analyzed the resultant graft–tunnel contact pressure using an in vitro model of human cadaver 8mm hamstring grafts.Methods: Contact characteristics were assessed using both pressure sensitive films and a force sensor. Two screw sizes were investigated (8 and 9mm in an 8mm Sawbone tunnel), both with and without a bone wedge between graft and screw. Separately, time dependent relaxation of contact force was recorded over a one hour epoch and associated tendon water loss was measured. Pullout testing of 8mm tendon grafts from 8mm holes in Sawbone and porcine femora were performed after 1min and 1h.Results: During screw insertion, measured peak pressures (>40MPa) exceeded the compressive failure stress of metaphyseal bone by more than an order of magnitude. Using a bone wedge between tendon and screw reduced local peak pressure by 85% but produced also inferior average contact pressure. In all approaches, initially achieved graft contact pressure rapidly decreased to approximately 25% within 30min. Pullout strength was significantly reduced after 1h in comparison to 1min in porcine bone as well as Sawbone.Conclusion: Viscoelastic adaptation of the tendon is severe and critically reduces effective graft–bone contact pressure. Consideration of this newly recognized effect may open new and improved approaches for tendon graft fixation.

Computer assisted versus conventional total knee replacement: A comparison of tourniquet time, blood loss and length of stay - Corrected Proof

2011-12-26

Abstract: Aims and introduction: The aim of this study was to assess whether navigated total knee arthroplasty (TKA) reduces peri-operative blood loss and post-operative length of stay when compared to conventional total knee arthroplasty techniques.Patients and methods: A retrospective case-note review of 143 patients undergoing primary elective total knee arthroplasty was carried out. Two surgeons in this institution perform conventional knee arthroplasty using intramedullary alignment with another two surgeons using the computer assisted technique. Blood losses were calculated using the Meunier et al. (2008) [] method for calculation of peri-operative blood loss. This is based on changes in peri-operative blood indices compared to the patient's theoretical total blood volume which is calculated using the patient's pre-operative height and weight. Tourniquet time and post-operative length of stay for the two techniques of arthroplasty were also recorded.Results: Sixty eight patients underwent conventional TKA and 75 patients had navigated TKA's performed. This data showed no significant difference in blood loss (p=0.56) or post-operative length of stay (p=0.36). A significant difference in tourniquet time between the two techniques was demonstrated (p=0.01).Conclusion: In this study there was no significant reduction in post-operative length of stay and peri-operative blood loss when using computer-assisted techniques. There was an increase in tourniquet time with the computer-assisted technique that may have implications upon work productivity for primary cemented knee arthroplasty.

Association between in vivo knee kinematics during gait and the severity of knee osteoarthritis - Corrected Proof

2011-12-22

Abstract: Background: Osteoarthritis patients may exhibit different kinematics according to the disease stage. However, changes in the frontal and horizontal planes in each stage remain unclear. The purpose of this study was to investigate changes in the knee kinematic gait variables of osteoarthritis patients, including the frontal and horizontal planes, with respect to the severity of the disease.Methods: Forty-five patients with knee osteoarthritis and 13 healthy young subjects were recruited for the experiment. All subjects were examined while walking on a 10-m walkway at a self-selected speed. In each trial, we calculated the angular displacements of flexion/extension, abduction/adduction, and external/internal tibial rotation. We also measured muscle strength, range of motion (ROM), and alignment. We compared the differences in osteoarthritis severity and knee kinematic variables between osteoarthritis patients and normal subjects.Results: The flexion angle at the time of foot contact was significantly less in patients with severe and moderate osteoarthritis than in normal subjects (both p<0.01). The abduction angle at the 50% stance phase was significantly less in patients with severe osteoarthritis than in normal subjects (p<0.05). The excursion of axial tibial rotation was significantly less in patients with early osteoarthritis than in normal subjects (p<0.05).Conclusion: Osteoarthritis patients had different knee kinematics during gait, depending on the progress of osteoarthritis. Early-stage patients exhibit decreased axial tibial rotation excursion, while severe-stage patient exhibit increased knee adduction.

Computer guided restoration of joint line and femoral offset in cruciate substituting total knee arthroplasty - Corrected Proof

Gautam M. Shetty, Arun Mullaji, Sagar Bhayde — 2011-12-19

Abstract: Purpose: This prospective study aimed to evaluate radiographically, change in joint line and femoral condylar offset with the optimized gap balancing technique in computer-assisted, primary, cruciate-substituting total knee arthroplasties (TKAs).Methods: One hundred and twenty-nine consecutive computer-assisted TKAs were evaluated radiographically using pre- and postoperative full-length standing hip-to-ankle, antero-posterior and lateral radiographs to assess change in knee deformity, joint line height and posterior condylar offset.Results: In 49% of knees, there was a net decrease (mean 2.2mm, range 0.2–8.4mm) in joint line height postoperatively whereas 46.5% of knees had a net increase in joint line height (mean 2.5mm, range 0.2–11.2mm). In 93% of the knees, joint line was restored to within ±5mm of preoperative values. In 53% of knees, there was a net increase (mean 2.9mm, range 0.2–12mm) in posterior offset postoperatively whereas 40% of knees had a net decrease in posterior offset (mean 4.2mm, range 0.6–20mm). In 82% of knees, the posterior offset was restored within ±5mm of preoperative values.Conclusions: Based on radiographic evaluation in extension and at 30° flexion, the current study clearly demonstrates that joint line and posterior femoral condylar offset can be restored in the majority of computer-assisted, cruciate-substituting TKAs to within 5mm of their preoperative value. The optimized gap balancing feature of the computer software allows the surgeon to simulate the effect of simultaneously adjusting femoral component size, position and distal femoral resection level on joint line and posterior femoral offset.Level of Evidence: Level II

Predictors and outcomes of lateral release in total knee arthroplasty: A cohort study of 1859 knees - Corrected Proof

Samuel Molyneux, Ivan Brenkel — 2011-12-02

Abstract: The use of lateral retinacular release (LR) to improve patellar tracking during total knee arthroplasty (TKR) remains contentious. This cohort study explored which pre-operative factors predicted LR, and analysed the effect of LR on short term complications and long term outcomes. One thousand eight hundred fifty-nine TKR patients were followed up for a mean of 5.49years. One hundred fifty-four (8.3%) underwent LR. After regression analysis only, valgus deformity, year of surgery, maximal flexion and the operative surgeon predicted LR. LR patients stayed longer in hospital (10.8 vs 8.6days) and had higher transfusion rates (20.3% vs 10.1%) than non-LR patients, but patellar fracture and infection rates were the same. Range of motion was poorer in the LR patients, but AKS Knee and functional scores were unaffected long term.

Little clinical advantage of computer-assisted navigation over conventional instrumentation in primary total knee arthroplasty at early follow-up - Corrected Proof

Tao Cheng, Xiao-Yun Pan, Xin Mao, Guo-You Zhang, Xian-Long Zhang — 2011-11-30

Abstract: Purpose: Even though computer-assisted navigation systems have been shown to improve the accuracy of implantation of components into the femur and tibia, long-term results are lacking and there is little evidence yet that navigation techniques also improve functional outcomes and implant longevity following total knee arthroplasty (TKA). The aim of this study was to summarize and compare the clinical outcomes of total knee arthroplasties (TKAs) performed using navigation-assisted and conventional techniques.Methods: The study was conducted according to the guidelines described in the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statements. Methodological features were rated independently by two reviewers. A meta-analysis of randomized controlled trials (RCTs) or quasi- randomized controlled trials (qRCTs) was carried out to evaluate the efficacy of CAS versus conventional TKA. Data were pooled in fixed and random effects models and the weighted mean difference (WMD) and odds ratio (OR) were calculated. Heterogeneity across studies was determined, and subgroup analyses by the type of navigation system (image-based or image-free navigation system) were conducted.Results: Twenty-one studies that included 2333 knees were collected from different countries. The surgical time was longer for CN TKA than for the conventional procedure. There was no significant difference in the Knee Society Score between the two groups at the 3-month and 6-month follow-up. The rates of postoperative complications in patients who had CN TKA were similar to those in the patients who had conventional TKA.Conclusion: No significant differences in short-term clinical outcomes were found following TKAs performed with and without computer navigation system. However, there is clearly a need for additional high-quality clinical trials with long-term follow-up to confirm the clinical benefits of computer-assisted surgery.

Corrigendum to “Translational and rotational knee joint stability in anterior and posterior cruciate-retaining knee arthroplasty” [The Knee 18 (2011) 491–495] - Corrected Proof

JiaHsuan Lo, Otto Müller, Torsten Dilger, Nikolaus Wülker, Markus Wünschel — 2011-11-28

The editor regrets that this paper was published erroneously as a case report. It is in fact an original article.

Arthroscopic second generation autologous chondrocytes implantation associated with bone grafting for the treatment of knee osteochondritis dissecans: Results at 6years - Corrected Proof

2011-11-24

Abstract: Purpose: The aim of this study was to analyze the clinical outcome obtained with arthroscopic second generation autologous chondrocyte implantation (ACI) associated with bone grafting for the treatment of knee osteochondritis dissecans (OCD) at medium term follow-up.Methods: Thirty-four knees affected by symptomatic OCD grade III or IV on the ICRS (International Cartilage Repair Society) scale were treated and prospectively evaluated at 12, 24months of follow-up, and at a final mean 6±1years of follow-up. The mean age at treatment was 21±6years. The average size of the defects was 3±1cm2. Patients were evaluated with IKDC, EQ-VAS, and Tegner scores.Results: A statistically significant improvement in all scores was observed after the treatment. The IKDC subjective score improved from 38±13 to 81±20, and 91% of the knees were rated as normal or nearly normal in the objective IKDC at the final evaluation. EQ-VAS and Tegner scores showed a statistically significant linear trend of improvement over time passing from 52±18 to 83±14 and from 2±1 to 5±3, respectively, at 6years' follow-up. A better outcome was obtained in men, sport active patients, and smaller lesions.Conclusions: Second generation ACI associated with bone grafting is a valid treatment option for knee OCD and may offer a good and stable clinical outcome at mean 6years of follow-up. Further studies are needed to confirm the results over time, and determine if there is only a symptomatic improvement, or if this procedure may also prevent or delay further knee degeneration.

Arthroscopic treatment of synovial chondromatosis at the knee posterior septum using a trans-septal approach: Report of two cases - Corrected Proof

2011-11-21

Abstract: Synovial chondromatosis of the knee joint rarely develops in the posterior septum. Such cases are difficult to treat arthroscopically since the posterior septum is not readily accessible via standard portals. We report two cases of localized synovial chondromatosis in the posterior septum. We used a posterior trans-septal portal to arthroscopically remove the loose bodies and perform a concomitant synovectomy. The two cases were followed-up for 24 and 16months after surgery, respectively, and the patients were found to be pain-free, have a full range of knee motion and showed no evidence of recurrence. A posterior trans-septal portal may be essential in some cases for treatment of synovial chondromatosis at the posterior septum.

Corrigendum to “The early results of gender-specific total knee arthroplasty in Thai patients” [The Knee 18 (2011) 483–487] - Corrected Proof

Aree Tanavalee, Thana Rojpornpradit, Sukree Khumrak, Srihatach Ngarmukos — 2011-11-21

The editor regrets that this paper was published erroneously as a case report. It is in fact an original article.

Transcutaneous oxygen tension in the anterior skin of the knee after minimal incision total knee arthroplasty - Corrected Proof

Koji Aso, Masahiko Ikeuchi, Masashi Izumi, Tomonari Kato, Toshikazu Tani — 2011-11-14

Abstract: Background: Delayed wound healing after total knee arthroplasty (TKA) can lead to devastating complications. The lateral flap is reported to be more hypoxic than the medial flap in conventional TKA. However, the surgical approach significantly affects the cutaneous blood supply. Our hypothesis was that postoperative oxygenation of the skin over the anterior knee would be different in minimal incision TKA.Methods: This prospective observation study included 21 patients who underwent minimal incision TKA. Transcutaneous oxygen tension (TcPO2) was measured perioperatively at four sites around the midline incision: superio-medial, superio-lateral, inferio-medial, and inferio-lateral. The ratio of the regional TcPO2 to the reference TcPO2 was calculated as the regional perfusion index (RPI). We compared the RPI among four sites and evaluated the association between the RPI and wound healing.Results: At all measurement sites, the RPI significantly decreased after surgery (days 1 and 7; p<0.01). On day 7, the RPI at inferio-medial and inferio-lateral sites were significantly lower than superio-medial and superio-lateral sites, respectively (p<0.05). No significant difference between the medial and lateral sites was observed. In three patients, delayed healing was noted at the inferio-lateral wound edge, where the RPI significantly decreased on day 1.Conclusion: The distal part of the wound was significantly more hypoxic than the proximal part in minimal incision TKA. Atraumatic wound edge retraction should be carried out especially in the distal part. Although further investigation is necessary, delayed wound healing is potentially associated with regional skin hypoxia on day 1.

Aseptic loosening of the patellar component at the cement–implant interface - Corrected Proof

N.K. Rath, A.G. Dudhniwala, S.P. White, M.C. Forster — 2011-11-07

Abstract: We present four cases of aseptic loosening at the implant-cement interface following patellar resurfacing. All patients initially had good results, but then presented with onset of a new anterior knee pain. The radiographs including flexed lateral and skyline view of the knee were normal in all the cases. After carefully ruling out infection, aseptic loosening at the cement–implant interface was diagnosed on further investigation. Aseptic loosening of the patellar button at the implant-cement interface can be difficult to diagnose with standard knee radiographs. During flexed lateral radiograph of the knee and the skyline view radiograph of the patellofemoral joint, the patella is compressed on the femur and thereby reducing the loose patellar button. This phenomenon has not been previously described.Patients presenting with new onset of knee pain after an initial good results following patellar resurfacing require further investigation to exclude loosening at the cement–implant interface as plain radiographs can be misleading.

Cadaveric results of an accelerometer based, extramedullary navigation system for the tibial resection in total knee arthroplasty - Corrected Proof

Denis Nam, Christopher J. Dy, Michael B. Cross, Michael N. Kang, David J. Mayman — 2011-10-28

Abstract: Introduction: In total knee arthroplasty, the accuracy and precision of the tibial resection must be improved. The purpose of this study was to determine the accuracy and time associated with the use of an accelerometer based, extramedullary surgical navigation system for performing the tibial resection.Materials and methods: Four orthopedic surgeons performed a tibial resection utilizing the KneeAlign™ system, each on five separate, cadaveric tibiae. Each surgeon was assigned a preoperative “target” of varus/valgus alignment and posterior slope prior to each resection. The alignment of each resection was measured using both plain radiographs and computed tomography, along with the time required to use the device.Results: Regarding coronal alignment, the mean absolute difference between the preoperative “target” and tibial resection alignment was 0.77°±0.64° using plain radiograph, and 0.68°±0.46° using CT scan measurements. Regarding the posterior slope, the mean absolute difference between the preoperative “target” and the tibial resection was 1.06°±0.59° using plain radiograph, and 0.70°±0.47° using CT scan measurements. The time to use the KneeAlign™ for the fifth specimen was less than 300s for all four orthopedic surgeons in this study.Discussion: This cadaveric study demonstrates that the KneeAlign™ system is able to accurately align the tibial resection in both the coronal and sagittal planes.Level of evidence: Cadaveric study.

The effect of medial condylar bone loss of the knee on coronal plane stability—A cadaveric study - Corrected Proof

2011-10-28

Abstract: Introduction: The quantitative effects of medial bone loss of the knee on both leg alignment and coronal plane stability are poorly understood.Materials and methods: Utilizing computer navigation, 5mm bone defects of the medial distal femur (MDF), medial posterior femoral condyle (MPF), and medial tibial plateau (MT) were simulated in 10 cadaveric limbs, and alignment of the knee at various degrees of flexion were analyzed when applying standardized varus and valgus loads.Results: The 5mm MPF defect significantly increased varus laxity at 90° of flexion by 3.3°±1.2° (p=0.019), a 5mm MDF defect resulted in a 2.2°±1.7° (p=0.037) and a 2.1°±1.3° (p=0.023) increase in laxity at 0° and 30° of flexion, respectively, and a 5mm MT defect increased varus laxity at all flexion angles by 4.0° to 7.0°, but was only statistically significant at 30° (p=0.026).Discussion: This study confirms and quantifies the theories of flexion and extension gap balancing, and pseudolaxity of the medial collateral ligament in the varus knee, the results of which can be used in preoperative planning and intraoperative decision making for both total knee and unicondylar arthroplasty.

Cardiovascular disease predicts complications following bilateral total knee arthroplasty under a single anesthetic - Corrected Proof

2011-10-28

Abstract: Introduction: This study evaluated the rate of perioperative complications of single anesthetic bilateral total knee arthroplasties (TKA) compared with staged procedures.Methods: The records of all single anesthetic bilateral TKA performed between 1997 and 2007 at one large community hospital and one university hospital were retrospectively reviewed. Complete demographic data, preoperative co-morbidities and complications for 156 patients were compared to a matched staged bilateral TKA (n=78) cohort.Results: In the single anesthetic bilateral TKA cohort, cardiovascular disease predicted postoperative myocardial (p<0.01, Odds Ratio — 67.6), need for ICU admission (p<0.01, Odds Ratio — 88.8), and days spent in ICU (p<0.01), while cardiovascular disease did not significantly predict postoperative MI in the staged bilateral (p=0.99, OR — 0).Conclusion: Patients with cardiovascular disease are at higher risk for perioperative MI after single anesthetic bilateral TKA.

Longitudinal analysis of T1ρ and T2 quantitative MRI of knee cartilage laminar organization following microfracture surgery - Corrected Proof

2011-10-24

Abstract: Objective: To quantitate longitudinally the radiographic properties of different layers of repaired tissue following microfracture (MFx) surgery using T1ρ and T2 magnetic resonance imaging (MRI).Design: 10 patients underwent MFx surgery to treat symptomatic focal cartilage defects (FCD). Sagittal three-dimensional (3D) water excitation high-spatial resolution (HR) spoiled gradient recalled (SPGR) for quantitative T1ρ and T2 mapping were acquired for each patient 3–6months and 1year after surgery. Cartilage compartments were segmented on HR-SPGR images, and T1ρ and T2 maps were registered to the HR-SPGR images. T1ρ and T2 values for the full thickness of deep and superficial layers of repaired tissue (RT) and normal cartilage (NC) were calculated, and compared within and between respective time points. A p-value <0.05 is considered statistically significant.Results: The majority of FCD were found in the MFC. The average surface area of the lesions did not differ significantly overtime. At 3–6months, RT had significantly higher full thickness T1ρ and T2 values relative to NC. At 1year, this significant difference was only observed for T1ρ values. At 3–6months follow-up, the RT's superficial layer had significantly higher T1ρ and T2 values than the deep layer of the RT and the superficial layer of NC. At 12months, the superficial layer of the RT had significantly higher T1ρ values than the RT's deep layer and the NC's superficial layer.Conclusion: T1ρ and T2 MRI are feasible methods for quantitatively and noninvasively monitoring the maturation of repaired tissue following microfracture surgery over time.

A low-riding patella in posterior stabilised total knee replacements alters quadriceps' mechanical advantage, resulting in reduced knee flexion moments - Corrected Proof

2011-10-20

Abstract: Abnormal in vivo Total Knee Replacement (TKR) kinetics is influenced by a range of factors, particularly by changes to the knee's geometric parameters such as the patellar tendon moment arm (PTMA). In this study, ground reaction force (GRF) measurements were combined with simultaneous fluoroscopic image measurements to investigate the relationship between abnormal TKR kinetics and geometric parameters. Nine Scorpio Cruciate Retaining (CR) TKR (Stryker, Newbury, UK), nine Scorpio Posterior Stabilized (PS) TKR and seven normal subjects performed a step-up activity on a forceplate in view of a fluoroscope. The TKR subjects were part of a larger ongoing randomised controlled trial. The maximum external knee flexion moment was 22.0% lower in the Scorpio PS group compared to the Scorpio CR group. No significant differences in PTMA were found between the groups. The Scorpio PS had a low-riding patella, with a 30.7% reduction in patellar height compared to the Scorpio CR. This was probably due to using a thick tibial insert after PCL release in the PS, and led to an 8° increase in patellar flexion angle which altered the patellar mechanism and reduced quadriceps' mechanical advantage. Consequently, PS subjects stepped-up more cautiously with a reduced knee flexion moment.

Does 99mTc-MDP bone scintigraphy add to the investigation of patients with symptomatic unicompartmental knee replacement? - Corrected Proof

Min Yen Wong, Clare Beadsmoore, Andoni Toms, Toby Smith, Simon Donell — 2011-10-18

Abstract: Aim: The purpose of this study was to determine whether nuclear medicine 99mTc-Methyl diphosphonate bone scintigraphy (99mTc-MDP bone scintigraphy) added information over plain radiographs loosening infection in symptomatic unicompartmental knee replacements (UKRs).Methods and materials: A cohort of 39 patients who presented with knee pain following UKR was retrospectively reviewed. All had undergone nuclear medicine bone scans for possible loosening or infection of the prosthesis. The findings of the bone scintigraphy were compared to subsequent operative findings during diagnostic arthroscopic investigation or revision surgery for those patients who had undergone these procedures.Results: Of the 39 patients with painful knees following UKR, surgical findings confirmed that 11 had either loose (n=9) or infected (n=2) implants. Logistic regression analysis demonstrated no statistically significant combination of features on nuclear medicine or radiographs associated with failure of the prosthesis due to infection or loosening (p>0.05).Classification of a satisfactory position of the UKR on plain radiography exhibited a high negative predictive value (96% for infections, and 80% for loosening). However, plain radiograph was not sensitive for loosening (50%) or infection (37%) of the UKR with very low positive predictive values (9.1% for infection and 27.3% for loosening).Conclusion: This study provides no evidence to support the routine use of 99mTc-MDP bone scintigraphy in the clinical decision-making for patients with a painful UKR.Level of evidence: level 4.

Patellar tracking after total knee arthroplasty performed without lateral release - Corrected Proof

Chae-Gwan Kong, Hyun-Min Cho, Kyung-Hwan Suhl, Min-Up Kim, Yong In — 2011-10-18

Abstract: There is limited clinical data on patellar maltracking in patients who have undergone total knee arthroplasty (TKA) without lateral release. We performed a retrospective review of 191 consecutive TKAs performed by one surgeon through the subvastus approach without lateral release from 2007 to 2008. Radiographic measurements were made using the preoperative and postoperative 2years radiographs. Multivariate logistic regression analysis was performed to determine the risk factors for patellar maltracking after TKA performed without lateral release. TKA resulted in increases in the patellar tilt and displacement (P<0.05). The presence of preoperative patellar tilt and displacement were predictive of postoperative patellar tilt and displacement in patients who underwent TKA through the subvastus approach without lateral release (P<0.05).

Improved quadriceps' mechanical advantage in single radius TKRs is not due to an increased patellar tendon moment arm - Corrected Proof

2011-10-17

Abstract: Single femoral radius TKRs have been reported to improve quadriceps' mechanical advantage, leading to enhanced patient function. An increased patellar tendon moment arm (PTMA) has been cited as the main feature leading to improved quadriceps' mechanical advantage. However, these designs often incorporate a recessed trochlea which alters the patellar mechanism and may contribute to improved quadriceps' mechanical advantage. This study simultaneously measured the PTMA using two and three dimensional methods, as well as quadriceps forces (QF), patellofemoral kinematics and tibiofemoral kinematics in a motion analysis laboratory during an open chain leg extension activity. Six cadaveric knees were tested in the normal state and after implantation of three different single femoral radius TKR designs: cruciate retaining, posterior stabilised and rotating platform posterior stabilised (Stryker, Newbury, UK). QFs in the TKRs were between 15% and 20% lower than normal between 60° and 70° flexion. The increase in PTMA was insufficient to explain the reduced QF in the TKRs. The patellar flexion angle (PFA) of the TKRs was lower than normal at knee flexion angles greater than 50°, probably as a result of the recessed trochlea. A simple patellar model demonstrated that the reduced PFA may explain a large proportion of the reduction in QF after single radius TKR.

Spontaneous patella fracture presenting as osteomyelitis in focal dermal hypoplasia - Corrected Proof

Eric L. Altschuler, Richard S. Yoon, Richard Dentico, Frank A. Liporace — 2011-10-17

Abstract: We report the first case of the assessment and treatment of a spontaneous patellar fracture in a patient with Goltz syndrome—a rare dermal hypoplasia. This case illustrates the non-straightforward presentation of a spontaneous patellar fracture in seemingly osteoporotic bone stock further complicated by the inability to rule out osteomyelitis. In this confusing presentation, a high index of suspicion for patella fracture should be maintained for patients with knee pain and osteoporosis on x-ray with a dysplastic syndrome.

Fixed flexion deformity following total knee arthroplasty. A prospective study of the natural history - Corrected Proof

Conal Quah, Girish Swamy, James Lewis, John Kendrew, Nitin Badhe — 2011-10-14

Abstract: Introduction: Stiffness following total knee arthroplasty (TKA) is a disabling problem resulting in pain and reduced function.Objective: The aim of our study was to evaluate the natural course of fixed flexion deformity (FFD ) following primary total knee arthroplasty.Methods: Prospective review of 1626 patients undergoing primary TKA from 2001 to 2006 with a minimum of 4year follow up. Demographic data included post-operative range of motion; type of prosthesis used, treatment modalities for stiffness and the final range of motion were recorded. FFD was defined as class 1(5–15 degrees) and Class 2 (> 15 degrees). Patients with a pre-operative FFD of >15, infection, stiffness treated with manipulation or revision surgery were excluded from the study.Results: Of the 1626 patients evaluated, 170 (10.5%) presented with a FFD. 18 patients were excluded from the study and 16 were lost to follow up. 124 (91.2%) were class 1 and 12 (8.8%) were class 2. FFD improved from a mean of 8.8 degrees to 0.4 degrees (p<0.0001) in 11.4months. In 94.1% patients the FFD completely resolved (i.e. < 5 degrees) at a mean of 10.8months (p<0.0001). In the remaining 5.9% of patients, FFD improved from a mean of 16.4 to 6.9 degrees at a mean follow up of 21.5months (p<0.0001).Conclusion: A gradual improvement in the FFD can be expected up to 2years and a small residual flexion contracture does not cause functional deficit.Level of evidence: Prospective cohort study, level 3.

Patellofemoral joint stress during running in females with and without patellofemoral pain - Corrected Proof

Adam D. Wirtz, John D. Willson, Thomas W. Kernozek, Di-An Hong — 2011-10-14

Abstract: Patellofemoral pain (PFP) is a common complaint among female runners. The etiology for PFP is frequently associated with increased patellofemoral joint stress (PFJS) and altered hip and knee joint kinematics during running. However, whether PFJS during running is increased among runners with PFP is unknown. The primary aim of this study was to compare PFJS during running among females with and without PFP. We also compared hip and knee transverse plane kinematics during running due to their potential influence on patellofemoral contact area and PFJS. Three dimensional hip and knee running kinematics and kinetics were obtained from 20 females with PFP and 20 females with no pain. Patellofemoral joint stress during running was estimated using patellofemoral contact area and a sagittal plane patellofemoral joint model previously described. Patellofemoral joint stress, PFJS-time integral, and hip and knee transverse plane kinematics at the time of impact peak and peak ground reaction force were compared between groups using a multivariate analysis of variance. The results show that peak PFJS and PFJS-time integral were similar between groups. Peak knee flexion angle and net knee extension moment were not different between groups. However, females with PFP demonstrated hip internal rotation that was 6° greater (P=0.04) when ground reaction forces were greatest. The extent these results are influenced by compensations for pain is unclear. However, if increased PFJS contributes to the etiology or exacerbation of PFP, interventions to minimize altered transverse plane hip kinematics may be indicated among runners who demonstrate this characteristic.

Complex total knee arthroplasty using resection prostheses at mid-term follow-up - Corrected Proof

Ben Molenaers, Nele Arnout, Johan Bellemans — 2011-10-07

Abstract: Complex primary or revision TKA may require the use of a resection type prosthesis to address major bone loss and soft tissue deficiencies. The aim of this retrospective study is to evaluate the clinical and radiographic outcomes of salvage knee reconstructions in a larger cohort and longer follow-up than previously reported.We therefore present the results of 66 cases treated with the Finn/OSS knee system with an average follow-up of 5years (range 2–12). Indications included 63 revision cases and three primary interventions with either massive bone loss and/or soft tissue deficiency.At final follow-up the average knee society score had significantly improved from 46 preoperatively to 73, and the function score improved from 27 to 47 points. Four cases needed to be revised: one for recurrent infection, two for aseptic loosening and one for implant breakage. Nine patients underwent minor reinterventions; including five cases with irrigation and debridement for prolonged wound drainage, two patellar realignment procedures and two extensor mechanism repairs. Two patients developed a peroneal nerve palsy. Overall implant survivorship with revision as the endpoint was 92% at 5 and 10years.We conclude that the use of a resection prosthesis in the complex primary and revision TKA leads to acceptable results, but the complication rate is relatively high.

Survivorship of UKA in the middle-aged - Corrected Proof

Thomas J. Heyse, Ahmed Khefacha, Geert Peersman, Philippe Cartier — 2011-10-03

Abstract: Background: Unicompartmental knee arthroplasty (UKA) is known to be a viable procedure allowing for preservation of the intact compartments and delivering excellent function at long-term follow-up. The primary purpose of this single-surgeon study was to analyse the survivorship of a fixed bearing UKA in patients younger than 60years.Methods: From all UKAs implanted between 1993 and 2005 at the senior authors' centre, 223 patients <60years at operation with a minimum follow-up of 5years were identified including all-poly and metal-backed tibiae. They were evaluated applying the Knee Society Score (KSS) at latest follow-up. Survivorship was calculated using Kaplan–Meier analysis, which considered the following variables: gender, type of tibial implant, medial vs. lateral UKA, and age.Results: Average age at index operation was mean 53.7 (SD 5.8, range 30–60) years at a mean follow-up of 10.8 (SD 3.5, range 5–17) years. From the KSS, the knee score was 94.3 (SD 7.8) and the function score was 94.9 (SD 6.8). At latest follow-up, the implant survival rate was 94.3%. Survivorship for the entire cohort was 93.5% at 10years (medial UKA 94.1% vs. lateral 91.8%), and 86.3% at 15years (85.1% medial vs. 91.7% lateral)Conclusion: In conclusion, excellent survival and function outcomes were noted in this subgroup of patients younger than 60years. Revision rates were comparable to those studies in which UKA was performed on an elderly patient population. UKA can successfully be performed in patients younger than 60years with appropriate patient selection.

A feasibility study for a pragmatic randomised controlled trial comparing cast immobilisation versus no immobilisation for patients following first-time patellar dislocation - Corrected Proof

Bernadette M. Armstrong, Michelle Hall, Edward Crawfurd, Toby O. Smith — 2011-09-30

Abstract: Background: The purpose of this feasibility study was to begin to determine the efficacy of cylinder cast immobilisation compared to no form of immobilisation for patients following first-time patellar dislocation (FTPD).Materials and methods: Participants were patients who attended a National Health Service Accident and Emergency department following a FTPD. Patients were randomised to receive immobilisation for four weeks in a cylinder cast followed by rehabilitation, versus no immobilisation and early rehabilitation. All patients were followed-up over a three month period, assessed using the Visual analogue scale for pain, Short Form-36, the Lysholm knee score and the Modified Functional Index.Results: Forty-one patients were approached to participate. Eight satisfied the pre-defined eligibility criteria and were randomised between the two groups. Whilst the results indicated a trend for superior short-term functional outcomes for those patients not immobilised compared to those immobilised following a FTPD, the small sample and baseline imbalances between the groups may have had a substantial influence on the results.Conclusion: This feasibility study has indicated that the outcome measurements adopted were appropriate to answer this research question, but the assessment of return to normal activity, recurrent instability and dislocation and cost-effectiveness over a longer follow-up period is recommended. Similarly, defining a more pragmatic eligibility criteria and recruiting from multiple centres would be recommended for the definitive trial requiring a sample of 348 patients to demonstrate a statistical significant treatment effect.Level of evidence: Level 2b

Decellularization of bovine anterior cruciate ligament tissues minimizes immunogenic reactions to alpha-gal epitopes by human peripheral blood mononuclear cells - Corrected Proof

Ryu Yoshida, Patrick Vavken, Martha M. Murray — 2011-09-19

Abstract: Rupture of ACL is a common injury. While the current surgical treatments are effective, many patients still suffer from precocious osteoarthritis, and there is an increasing interest in bioengineering approaches to improve ACL repair. Bovine collagen is a material currently in use for tissue engineering of ligaments. The alpha-gal epitopes found on bovine cells are a source of immunogenic stimulus for human cells. In this study, we wished to determine if those epitopes could be removed sufficiently to mitigate an immunogenic response using either a decellularization protocol or decellularization followed by alpha-galactosidase treatment. Bovine ACLs were treated with Triton-X, sodium deoxycholate, ribonuclease, and deoxyribonuclease to remove cells. A subset of the decellularized tissues was further treated with alpha-galactosidase. Human peripheral blood mononuclear cells (PBMCs) were exposed to untreated, decellularized, and alpha-galactosidase-treated tissues, and PBMC migration and IL-6 release were measured. PBMCs were significantly more attracted to untreated ACL compared to decellularized or alpha-galactosidase-treated tissue, but no difference was seen between the two treatment groups. PBMCs also released significantly more IL-6 when exposed to untreated tissue compared to decellularized ACL or alpha-galactosidase-treated ACL, but no difference was seen between the two treatment groups. Immunohistochemistry using anti-alpha-gal antibody detected the epitopes throughout the untreated ACL, but similar areas of reaction were not seen on decellularized or alpha-galactosidase-treated ACL. These results suggest that our decellularization protocol minimizes the immunogenic reactions of human PBMCs to bovine ACL tissue. Therefore, decellularized bovine ACL tissue may be a safe, effective biomaterial for ACL injury treatments.

Long term results of fixed-hinge megaprostheses in limb salvage for malignancy - Corrected Proof

2011-09-12

Abstract: We retrospectively studied the files of 669 patients with musculoskeletal tumors treated with limb salvage and reconstruction using fixed-hinge knee megaprostheses. We used the KMFTR® prosthesis from 1983 to 1989 in 126 patients, and the HMRS® prosthesis thereafter in 543 patients because of the anatomical femoral stem with one lateral flange for improved stress-shielding, the new hinge design and new generation polyethylene placed centrally in the metallic hinge, and the improved function compared to the former prosthesis. Distal femoral reconstructions were done in 474, proximal tibia in 163, extrarticular knee joint in nine, and total femoral in 23 patients. At 10 and 20years follow-up, survival to breakage was 95% and 85%, to aseptic loosening 94% and 82%, to infection 90% and 82%, and to polyethylene wear 95% and 37%. A statistically significant higher survival to breakage of the HMRS® prostheses was observed. No statistical difference of survival to breakage regarding the site of reconstruction, aseptic loosening, infection, polyethylene wear and mean functional score between the two types of prostheses was observed.

The intraoperative gap difference (flexion gap minus extension gap) is altered by insertion of the trial femoral component - Corrected Proof

Takehito Hananouchi, Kengo Yamamoto, Wataru Ando, Kazumasa Fudo, Kenji Ohzono — 2011-09-05

Abstract: A Tensor/Balancer device has been recently developed in order to assess soft tissue balancing in total knee arthroplasty (TKA) under more physiological conditions. This device allows us to measure the joint gap with a trial femoral component in place with the patella reduced. The purpose of this study was to clarify whether the placement of the component changes the intraoperative gap difference (flexion gap distance minus extension gap distance). We prospectively investigated the extension (0°) and flexion (90°) gaps in 73 posterior-stabilized TKAs under 30lb of joint distraction force. Then, we compared the gap difference with and without the trial femoral component in place. Our results showed that the intraoperative gap difference with the trial femoral component in place was larger than the intraoperative gap difference without the trial component (p=0.00003; with the trial component: mean 4.7mm (standard deviation (SD): 3.0mm); without the trial component: mean 2.7mm (SD: 3.3mm)). We consider that the change in gap difference with or without femoral component was caused by a relative difference in the elasticity and/or tightness of the soft tissue in extension versus flexion. Surgeons should be aware of this effect of the femoral component when considering intraoperative soft tissue balancing which leads to postoperative stability of the knee joint consequently.

An enhanced recovery programme for primary total knee arthroplasty in the United Kingdom — follow up at one year - Corrected Proof

D.A. McDonald, R. Siegmeth, A.H. Deakin, A.W.G. Kinninmonth, N.B. Scott — 2011-08-31

Abstract: The concepts of Enhanced Recovery Programmes (ERP) are to reduce peri-operative morbidity whilst accelerating patient's rehabilitation resulting in a shortened hospital stay following primary joint arthroplasty. These programmes should include all patients undergoing surgery and should not be selective. We report a consecutive series of 1081 primary total knee arthroplasties undergoing an enhanced recovery programme with a one year follow up period. A comparative cohort of 735 patients from immediately prior to the enhanced recovery programme implementation was also reviewed. The median day of discharge home was reduced from post-operative day six to day four (p<0.001) for the ERP group. Post-operative urinary catheterisation (35% vs. 6.9%) and blood transfusion (3.7% vs. 0.6%) rates were significantly reduced (p<0.001). Within the ERP group median pain scores (0 = no pain, 10 = maximal pain) on mobilisation were three throughout hospital stay with 95% of patients ambulating within 24h. No statistical difference was found in post-operative thrombolytic events (p=0.35 and 0.5), infection (p=0.86), mortality rates (p=0.8) and Oxford Knee Scores (p=0.99) at follow up.This multidisciplinary approach provided satisfactory post-operative analgesia allowing early safe ambulation and expedited discharge to home with no detriment to continuing rehabilitation, infection or complication rates at one year.

Effects of knee bracing on postural control after anterior cruciate ligament rupture - Corrected Proof

2011-08-29

Abstract: Study design: Randomized clinical trial.Objectives: To investigate the effects of functional knee braces on postural control in patients with anterior cruciate ligament (ACL) rupture.Background: ACL rupture leads to both mechanical knee instability and deficits in proprioception. Although elastic knee braces do not increase mechanical stability, patients report improved stability when wearing a brace. Elastic braces were found to reduce the loss of proprioception. It is, however, still unclear whether they also improve postural control, which involves the processing of proprioceptive input at a higher level.Methods: We studied 58 patients with isolated unilateral ACL rupture using computerized dynamic posturography and compared overall stability index (OSI) scores for injured and uninjured legs with and without a knee brace. In addition, patients were classified as copers and non-copers depending on knee function.Results: Within subjects, OSI scores were 3.0±1.1° for uninjured legs when unbraced, 2.8±1.3° for uninjured legs when braced (p=0.17), 3.7±1.5° for unbraced injured legs, and 2.9±1.3° for braced injured legs (p<0.001). For the injured legs of copers and non-copers, OSI scores were 3.4°±1.2° for copers and 4.0°±1.6° for non-copers in the unbraced condition (p=0.11) and 2.7±1.0° for copers and 3.1±1.4° for non-copers in the braced condition (p=0.26).Conclusion: Elastic knee braces increase postural stability by approximately 22% in patients with ACL rupture. There was no difference in postural stability between uninjured and injured legs in the braced condition. One possible explanation is that bracing improves both proprioception and postural control.Level of evidence: Controlled clinical trial, level 2a.

Male subjects with early-stage knee osteoarthritis do not present biomechanical alterations in the sagittal plane during stair descent - Corrected Proof

2011-08-25

Abstract: Patients with osteoarthritis (OA) of the knee show a loss of functional independence due to difficulty performing tasks that require high demand of the knee joint, such as descending stairs. However, it is unclear how muscular and biomechanical changes were present in patients with OA in the early stages. Thus, the purpose of this study was to analyze the kinetics, kinematics and muscle activation of men with early-stage knee OA during stair descent and compare them with a healthy control group. We evaluated 31 volunteers who were divided into two groups. The Osteoarthritis Group (OAG) included 17 men with grade I or II knee OA (53±6years) and the Control Group (CG) included 14 healthy men (50±6years). We performed a kinematic evaluation of stair descent in the sagittal plane in order to analyze knee flexion angles. Electromyography (EMG) of the vastus lateralis muscle was also performed and the vertical ground reaction force was measured. The WOMAC questionnaire was administered to all volunteers. Statistical analysis consisted of the nonparametric Mann-Whitney U test for intergroup comparisons of all variables (p>0.05). There were no significant kinematic, kinetic or EMG differences between groups. For the WOMAC, the intergroup differences were significant in all three sections (pain: p=0.001, stiffness: p=0.008 and function: p=0.0005). In men with knee OA grade I or II, the stair decent is preserved in the sagittal plane, indicating that at these stages of the disease the functional adaptations are not expressed.

Single time angular deformity correction and treatment of knee instability in congenital fibular hemimelia. A case report - Corrected Proof

2011-08-25

Abstract: Background: Fibular hemimelia is the most frequently occurring congenital anomaly of long bones. These patients, among other deficiencies, have a poor development of the anterior cruciate ligament (ACL). Unless it causes clinically assessed instability of the knee, nonsurgical treatment is given. When surgical treatment is required, correction of angular limb deformity must be realized prior to ACL reconstruction.Methods: We present the case of a 16-year old patient with congenital fibular hemimelia. Physical examination showed genu valgum, anteromedial rotatory instability and recurvatum of the right knee. We decided to perform surgical correction of the angular deformities and ACL reconstruction in the same surgical time.Results: Twelve months after surgery, the patient had no evidence of clinical instability, with a range of motion from −5°–110° of the right knee. No claudication or gait instability was found. The KT-1000 arthrometer showed a difference of 2mm between both knees.Conclusion: The ACL reconstruction and corrective osteotomies of angular deformities performed in a single surgical procedure had a good clinical result in a 12month follow up-period, restoring stability of the knee and allowing a normal gait cycle.

Comparing the mid-vastus and medial parapatellar approaches in total knee arthroplasty: A meta-analysis of short term outcomes - Corrected Proof

2011-08-24

Abstract: Purpose: Proponents of a mid-vastus (MV) approach for primary total knee arthroplasties (TKA) stress its importance in preserving function of the extensor mechanism with earlier rehabilitation and decreased prevalence of lateral release. We conducted a meta-analysis of randomised and quasi-randomised controlled trials to compare functional outcomes of the standard medial parapatellar (PP) and mid-vastus (MV) approaches in primary knee arthroplasties.Methods: The study was conducted according to the guidelines described in the Cochrane Handbook for Systematic Reviews of Interventions. Methodological features were rated independently by two reviewers.Results: We included 18 studies involving 1040 patients with mean age of 69 (SD±2.7) for the MV and 68.8 (SD±2.8) for the PP group. Using a MV approach led to significant improvement in flexion (mean difference (MD) 8.88, 95% confidence interval (CI) 4.50 to 13.25, P<0.01) and visual analogue scale score (MD −1.72 95% CI −2.08 to −1.36, P<0.01) in the first week postoperatively and reduced the number of required lateral releases (risk difference −0.16 95% CI −0.30 to −0.01, P=0.03) with no increase in complication rates.Conclusion: We conclude that the MV approach may provide an alternative to the standard PP approach with earlier rehabilitation and decreased lateral release rates in primary TKA and no increase in complication rates.

LCS mobile bearing total knee arthroplasty without patellar resurfacing. Does the unresurfaced patella affect outcome? Survivorship at a minimum 10-year follow-up - Corrected Proof

Seamus O'Brien, David J. Spence, Luke O. Ogonda, David E. Beverland — 2011-08-19

Abstract: Background: Patellar resurfacing during total knee arthroplasty (TKA) remains controversial. The aim of this study was to evaluate the long-term outcomes of a mobile-bearing TKA without patellar resurfacing.Methods: We assessed the outcomes in 503 patients (600 knees) who had cemented LCS (low contact stress) mobile bearing TKA without patellar resurfacing at a minimum follow-up of 10years. Clinical outcome scores and radiological assessment were used.Results: Four knees were revised, two had bearing dislocation and nine patients (1.5%) had secondary resurfacing for anterior knee pain. There were no radiolucent lines or osteolytic defects on radiographic evaluation.The overall survivorship was 97.8% with re-operation for any reason as the endpoint.Conclusion: Non-resurfacing of the patella does not adversely affect the outcome of the LCS mobile bearing TKA at minimum 10years follow-up.

A comparative anatomical study of the human knee and six animal species - Corrected Proof

Benedikt L. Proffen, Megan McElfresh, Braden C. Fleming, Martha M. Murray — 2011-08-18

Abstract: Purpose: Animal models are an indispensable tool for developing and testing new clinical applications regarding the treatment of acute injuries and chronic diseases of the knee joint. Therefore, the purpose of this study was to compare the anatomy of the intra-articular structures of the human knee to species commonly used in large animal research studies.Methods: Fresh frozen cow (n=4), sheep (n=3), goat (n=4), dog (n=4), pig (n=5), rabbit (n=5), and human (n=4) cadaveric knees were used. Passive range of motion and intra-articular structure sizes of the knees were measured, the structure sizes normalized to the tibial plateau, and compared among the species.Results: Statistically significant differences in the range of motion and intra-articular structure sizes were found among all the species. Only the human knee was able to attain full extension. After normalization, only the pig ACL was significantly longer than the human counterpart. The tibial insertion site of the ACL was split by the anterior lateral meniscus attachment in the cow, sheep, and pig knees. The sheep PCL had two distinct tibial insertion sites, while all the other knees had only one. Furthermore, only in human knees, both lateral meniscal attachments were located more centrally than the medial meniscal attachments.Conclusions/clinical relevance: Despite the relatively preserved dimensions of the cruciate ligaments, menisci, and intercondylar notch amongst human and animals, structural differences in the cruciate ligament attachment sites and morphology of the menisci between humans and animals are important to consider when selecting an animal model.

Does preoperative anxiety and depression predict satisfaction after total knee replacement? - Corrected Proof

Julia Blackburn, Adnan Qureshi, Rouin Amirfeyz, Gordon Bannister — 2011-08-17

Abstract: Background and purpose: Approximately one fifth of patients are not satisfied with the outcome of total knee arthroplasty (TKA). Preoperative variables associated with poorer outcomes are severity and chronicity of pain, psychological disease, poor coping strategies and pain catastrophisation. Psychological disease may be expressed as anxiety and depression. It is unclear whether anxiety and depression before TKA are constitutional or result from knee pain. The aim of this study was to explore the association of anxiety and depression with knee pain and function using specific outcome measures.Methods: Forty consecutive patients undergoing TKA completed Hospital Anxiety and Depression Scale (HAD) and Oxford Knee Scores (OKS) preoperatively and at 3 and 6months postoperatively.Results: The HAD and OKS significantly improved post-operatively (p<0.001). There was a greater change between the preoperative and postoperative scores in the OKS than the HAD. The severity of preoperative anxiety and depression was associated with higher levels of knee disability (coefficient −0.409, p=0.009). Postoperatively reduction in anxiety and depression was associated with improvement in knee disability after 3 (coefficient −0.459, p=0.003) and 6months (coefficient −0.428, p=0.006).Interpretation: The difficulty in interpreting preoperative anxiety and depression and the outcome of TKA is establishing whether they are the cause or effect of pain in the knee. As anxiety and depression improve with knee pain and function, this study suggests that knee pain contributes to the psychological symptoms and that a successful TKA offers an excellent chance of improving both.

Revision for stiffness following TKA: A predictable procedure? - Corrected Proof

Gregory K. Kim, S.M. Javad Mortazavi, Javad Parvizi, James J. Purtill — 2011-08-12

Abstract: Background: Stiffness is a known complication following total knee arthroplasty. Multiple options are available to address this problem but revision TKA has been reported to be an effective treatment especially in the presence of technical issues such as oversized or loose components. However, it is not clearly known what factors may affect the outcome of revision TKA for stiffness. The purpose of this study was to evaluate the results of TKA revision for stiffness and to determine which potential factors may predict the outcome.Materials and methods: Between 1999 and 2006, 39 patients (24 females and 15 males) were revised for stiffness following their primary TKA. The average age was 60.8years with an average BMI of 30.7. The mean follow up was 74.4months.Results: Following revision TKA, the overall range of motion and flexion contracture improved significantly from 68 to 90 (p=0.001) and from 14 to 5 (p<0.0001), respectively. Although the KSS were significantly improved from 45.72 to 77.10 (p<0.0001), the functional score did not improve significantly. Of the 39 knees which had stiffness, 10 (25.6%) required a second revision. We could not find any demographic or operative characteristics as a predictor failure.Conclusion: Our study shows that TKA revision is a viable option, still unpredictable, to improve the ROM in patients with prolonged stiffness after TKA. Although revision for stiffness is not always successful in terms of achieving functional range of motion, it could improve pain in presence of less than functional range of motion.Level of evidence: Prognostic Level II.

Gap changes after popliteus-tendon resection in PS-TKA: A cadaveric study in Thai female knees - Corrected Proof

2011-08-12

Abstract: Popliteus-tendon injury during total knee arthroplasty (TKA) may result in imbalanced soft-tissue tension; however, it is unclear whether complete popliteus-tendon resection is a factor which contributes to knee instability following TKA. We performed an isolated complete resection of the popliteus tendon during a standard posterior stabilised TKA (PS-TKA) in 14 normal knees of Thai female cadavers and measured gap differences in both knee flexion and extension. In addition, we measured the distance from the femoral attachment of the popliteus tendon to the femoral condyles including the distance from the most distal femoral attachment of the popliteus tendon to the distal lateral femoral condyle (DFa-DLFC), and the distance from the most posterior femoral attachment of the popliteus tendon to the posterior lateral femoral condyle (PFa-PLFC). After completion of bone cuts, static flexion and extension gaps were measured with a tension of 98N under intact and complete tendon resection, respectively. The mean DFa-DLFC and PFa-PLFC distances were 8.9mm (range, 6.4–10.5mm) and 11.5mm (range, 9.5–14.0mm), respectively. Of 14 cadaveric knees, 35.7% had a DFa-DLFC distance <9mm. Flexion and extension gaps significantly increased in both medial and lateral sides after complete popliteus resection with a similar mean increased value of 1.85mm. The clinical evaluation of gap changes after popliteus resection on knee stability should be further investigated. A routine 9-mm distal femoral bone cut may injure the popliteus tendon during TKA conducted on small knees.