The Knee - Articles in Press

Intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty - Corrected Proof

2010-03-08

Abstract: Cement articulating spacers have been used for the treatment of TKA infection. The disadvantages of commercially available pre-made mobile spacers include limitations in implant size and antibiotic dose, often allowing delivery of only a single antibiotic agent. Hand-made mobile spacers fail to provide a well-shaped and congruently articular surface and have difficulties in maintaining stability. We present a method of intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty. A custom mold was made intraoperatively with bone cement and the standard posterior stabilized TKA provisional components which were of the same size as the original prosthesis. Fabrication of the spacers did not increase the overall surgical time. From 2004 to 2007, 17 infected total knee arthroplasties were treated with two-stage reimplantation. The average length of follow-up was 31months. One patient required an above-knee amputation for persistent infection. A knee arthrodesis was performed in one case. Ten patients received reimplantation with Nexgen LCCK knee implants. Articulating spacers were retained in situ in five patients. This articulating spacer can help improve knee mobility and function during the interval between stages.

Tibial avulsion fracture of the posterior root of the medial meniscus in a skeletally-immature child — A case report - Corrected Proof

Matthew J. Matava, Young-Mo Kim — 2010-03-04

Abstract: It has been theorized that a traumatic tibial avulsion fracture of the posterior root of the medial meniscus (MM) is the cause of the so-called meniscus ossicle (MO). We report the delayed appearance of a tibial avulsion fracture of the posterior root of the MM after a valgus, twisting injury in a 12-year-old boy with open physes. Magnetic resonance imaging (MRI) scans performed 3days after the injury did not demonstrate a definitive tibial avulsion fracture of the posterior root of the MM; whereas, a repeat MRI for 3months post-injury did. Medial extrusion of the MM was also noted on the 3month MRI. Arthroscopic reattachment of the avulsed posterior root of the MM using a trans-physeal nonabsorbable suture tied over a proximal tibia staple was performed. Follow-up MRI at 6months postoperatively demonstrated healing of the tibial avulsion fracture of the posterior root of the MM in an anatomic position. The patient had a complete resolution of symptoms and there was no angular deformity or limb-length discrepancy at 2years postoperatively. To our knowledge, this is the first report describing a tibial avulsion fracture of the posterior root of the MM in a skeletally-immature patient successfully treated by a trans-physeal arthroscopic suture. This case also illustrates the development of the MO of the posterior root of the MM.

Fixation strength of the interference screw in the femoral tunnel: The effect of screw divergence on the coronal plane - Corrected Proof

2010-03-03

Abstract: Clinical studies to examine the effect of screw divergence have not been applied to the fixation of hamstring grafts. A few previous reports have addressed the correlations between the loss of pullout strength and divergence on hamstring tendon fixation in biomechanical tests. The purpose of this study was to examine the effect of interference screw divergence on the coronal plane when digital flexor tendons were fixed with an interference screw.Twenty fresh porcine hindlimb specimens were chosen. The grafts were fixed using titanium soft tissue interference screws. The hindlimbs were divided into two groups according to the insertion method of the screw. The screw was placed along the graft parallel to the long axis of the femoral tunnel in 10 specimens (parallel placement group), and the others were placed laterally at a 15° divergent angle from the bone tunnel on the coronal plane (divergence group). The cyclic-loading test was loaded for 1500cycles.Five specimens failed because of a pull-out of the tendon in divergence group. The number of specimens that failed before the completion of cycles in the divergence group was significantly greater than that in the parallel placement group. Although the residual displacement after 1500cycles for the divergence group was greater than that for the parallel placement group, no statistically significant difference was found between the groups.This study suggests that the screw placed laterally at a 15° divergent angle on the coronal plane decreases the fixation strength of the digital flexor tendons fixed with an interference screw.

Comparative anatomical measurements of osseous structures in the ovine and human knee - Corrected Proof

2010-03-02

Abstract: The ovine stifle has been increasingly used as a large animal model for the human knee. Still, comparative anatomical measurements of the knee in sheep and humans are missing. Thus, the purpose of this study was to describe and measure the osseous anatomy of the ovine stifle in comparison to the human knee. Twenty-four stifles of skeletal-mature merino-sheep and 24 human cadaver knees were obtained and distances between selected anatomical structures of the distal femur, the proximal tibia, and the patella were measured digitally and documented. Based on these, intercondylar ratio, tibial aspect ratio, patella aspect ratio and the cortical index were calculated. Regarding epicondylar width, lateral condylar width, medial condylar width and the tibial dimensions, the ovine stifle can be considered as a human knee scaled down by one third. However, sheep have a smaller trochlear width and a narrower femoral intercondylar notch than humans resulting in lower relative values for intercondylar width and intercondylar height. The distal femur's cortical index is the same in both species. In contrast, sheep have a massive bone stock below their tibial plateau and a proximal tibial shaft with remarkably thick cortical bone. The ovine stifle can be regarded as a useful model for the human knee. However, future studies should consider the differences in the femoral intercondylar notch width, the patellofemoral joint's biomechanics and the proximal tibia's cortical bone stock.

Combined lateral retinacular release with drilling chondroplasty for treatment of patellofemoral osteoarthritis associated with patellar malalignment in elderly patients - Corrected Proof

Chi-Chuan Wu — 2010-02-19

Abstract: This paper described a less invasive surgical technique that was performed for treatment of elderly patients with isolated patellofemoral (PF) osteoarthritis (OA) associated with patellar malalignment, although their tibiofemoral joints are minimally osteoarthritic.Two hundred and thirty-four knees in 126 consecutive elderly patients (average, 72yrs) diagnosed with combined disorders were treated by lateral retinacular release with drilling chondroplasty. The inclusion criteria were patient age ≥ 65yrs, isolated stage 2 or 3 PF-OA (modified Iwano staging by radiology), and a laterally subluxed patella shown on a Merchant's axial radiograph. Outcome was judged by three parameters: clinical PF function (modified Kujala scoring), congruence angle, and PF-OA staging. Two hundred and one knees in 107 patients were followed-up for an average of 4.2yrs (range, 2.1-7.5yrs) and 19 patients were lost to follow-up. No surgical complications occurred through the course of treatment. Clinical PF function improved in knees that showed unsatisfactory performance (modified Kujala scoring < 32) preoperatively, with 78.1% of the knees showing satisfactory performance (modified Kujala scoring ≥ 32) at the latest follow-up. Congruence angle improved in 85.6% of the knees and PF-OA staging improved in 77.1% of the knees. Combined lateral retinacular release with drilling chondroplasty is a feasible alternative for treatment of PF-OA associated with patellar malalignment in elderly patients where knee arthroplasty cannot be performed by various reasons. Advantages of this combined surgical technique include a less invasive procedure, minimal complication rate, and an acceptable success rate (78%, modified Kujala scoring≥32).

Fibular head osteotomy: A new approach for the treatment of lateral or posterolateral tibial plateau fractures - Corrected Proof

Baoqing Yu, Kaiwei Han, Ce Zhan, Chuncai Zhang, Hui Ma, Jiachan Su — 2010-02-18

Abstract: Background: A variety of surgical approaches have been employed previously for the open reduction and internal fixation of the fractures of lateral and posterolateral tibial plateau. However, the commonly used lateral approach does not provide adequate exposure and access to the posterolateral aspect of the lateral tibial plateau. We developed a new approach with osteotomy of fibular head to solve this problem and report its preliminary result.Methods: Eighty-two patients with lateral or posterolateral tibial plateau fractures had been treated by this approach. According to the fractures, partial or full heads of the fibula were removed, and knee joint function, including stability of the knee, was evaluated by X-ray and physical examinations.Results: All 82 cases were followed up for a mean of 3.2 y（2.0-5.6 y). In each case, the fractures were completely healed and knee joint function was restored. No infection or skin and bone necrosis were found. After one year following the operation, functional assessment of the knee joints by Rasmussen's functional grading system revealed a mean score of 27.9 (24-30). In addition, the radiological assessment by Rasmussen's anatomical grading system resulted in a mean score of 16.8 (14-18). Six patients experienced occasional pain or bad wither pain around knee joints, three of which had lateral-longitudinal instability of knee joint and three lost height of the tibial plateau.Conclusions: The new approach provides excellent visualization, which can facilitate the reduction and internal fixation for lateral or posterolateral tibial plateau fractures, and shows encouraging results.

Arthroscopic loose body removal and cyst decompression using a posterior trans-septal portal in the blind spot during knee arthroscopy—Technical report - Corrected Proof

Yong Seuk Lee, Jin Hwan Ahn, Byoung-Hyun Min, Kyung Wook Nha — 2010-02-17

Abstract: Some lesions such as cyst, loose body, and mass around the knee joint tend to localize at the posterior aspect of the proximal tibia. Although arthroscopic procedures of the knee joint's posterior compartment have been developed through posteromedial, posterolateral, and posterior trans-septal portals, the posterior aspect of the proximal tibia remains difficult to access and manipulate. We report an arthroscopic loose body removal and cyst decompression on the posterolateral aspect of the proximal tibia using a posterior trans-septal portal. This area represents a blind spot in knee arthroscopy.

15-year follow-up of PFC posterior cruciate retaining total knee arthroplasty - Corrected Proof

Lin Guo, Liu Yang, Jean Louis Briard, Xiao-jun Duan, Guang-xing Chen, Gang Dai — 2010-02-15

Abstract: Over 15 years’ follow up report of posterior cruciate ligament (PCL) retaining prosthesis is rare. This study was designed to evaluate long-term follow-up result of PFC cruciate retaining (CR) knee 22 prosthesis.One hundred and fifty three patients (178 knees) who had undergone PFC CR prosthesis TKA from September 1990 to March 1992 in the Center Medico-Chirurgical du Cèdre were followed-up. All cases were assessed clinically and radiographically using the rating system of KSS before surgery and at the time of follow-up. Revision for any reason was regarded as failure of prosthesis.Thirty one patients died and four patients were lost at the time of follow-up. One hundred and eighteen patients (125 knees) were successfully followed-up. Survivorship over 15 years was 93.7% with the endpoint of revision for any reason. Eleven knees were revised: five knees with severe osteolysis around both components, two painful knees with femoral component loosening with severe osteolysis and one with tibial loosening, one recurvatum, one infection and one painful knee with radiolucent loosening early postoperatively. The β angle in the un-revised patient group was 87.0±3.8 and in the revised group was 84.2±3.2 in the operated knee. There was statistical difference between these two groups (P<0.05).The 15-year survivorship of the PFC PCL retaining prosthesis was fair. Severe varus deformity of un-operated contralateral knee and severe tibial varus deformity of operated knee could be important factors related to prosthesis failure.

Knee proprioception following ACL reconstruction; a prospective trial comparing hamstrings with bone–patellar tendon–bone autograft - Corrected Proof

2010-02-11

Abstract: We prospectively studied knee proprioception following ACL reconstruction in 40 patients (34 men and six women; mean age 31years). The patients were allocated into two equal groups; group A underwent reconstruction using hamstrings autograft, and group B underwent reconstruction using bone–patellar tendon–bone autograft. Proprioception was assessed in flexion and extension by the joint position sense (JPS) at 15°, 45° and 75°, and time threshold to detection of passive motion (TTDPM) at 15° and 45°, preoperatively and at 3, 6 and 12months postoperatively. The contralateral healthy knee was used as internal control. No statistical difference was found between the ACL-operated and the contralateral knees in JPS 15°, 45° and 75° at 6 and 12months, in both study groups. No statistical difference was found between the ACL-operated and the contralateral knees in TTDPM 15° at 6 and 12months, nor regarding TTDPM 45° at 3, 6 and 12months, in group A. No statistical difference was found in JPS and TTDPM between the two grafts, at any time period. Knee proprioception returned to normal with ACL reconstruction at 6months postoperatively, without any statistically significant difference between the autografts used.

Anthropometric measurements of knee joints in Thai population: Correlation to the sizing of current knee prostheses - Corrected Proof

Chaiyos Chaichankul, Aree Tanavalee, Pibul Itiravivong — 2010-02-05

Abstract: Anthropometric data on the distal femoral condyle and the proximal tibia of 200 knees in 200 Thai subjects were measured using magnetic resonance imaging (MRI). The data including the resected femoral anterior–posterior (AP) length, the resected femoral medial–lateral (ML) width, the resected tibial AP length and the resected tibial ML width were measured. A characterization of the aspect ratio (the ML to AP dimensions) was made for the distal part of the femur and the aspect ratio (the AP to ML dimensions) was made for the proximal part of the tibia. All parameters were compared to the size of the total knee prosthesis with four prosthetic systems which currently used in Thailand: NexGen (Zimmer), P.F.C. Sigma (Depuy-Johnson & Johnson), Genesis II (Smith & nephew), and Scorpio (Stryker). The results of this study could provide fundamental data for the design of knee prostheses suitable for the Thai population.

Are pain and function better measures of outcome than revision rates after TKR in the younger patient? - Corrected Proof

2010-02-04

Abstract: Revision is the gold standard outcome measurement for survival analyses of orthopaedic implants but reliance on revision as an endpoint has been recently questioned. This study, that assesses long-term outcome in a specific group of patients who had undergone total knee replacement (TKR) for osteoarthritis, highlights the main problems facing modern survival analyses. Minimum 12-year survival and outcome data were reviewed for a series of sixty patients under the age of 60years (mean age 55.4years) who underwent total knee replacement (TKR) for osteoarthritis. The patients are a subgroup from a larger consecutive series of 1429 patients who underwent TKR between 1987 and 1993 at a single institution. Whilst the main study aim was to compare outcome of TKR using different endpoints, the outcome of TKR in this younger subpopulation could also be investigated.With revision as the primary endpoint the survival for TKR was 82.2% (95% CI 17.3). The mean OKS at follow-up (mean 15.7years) was 30.9. However, many of the 82% of patients who did not undergo revision had a less than satisfactory outcome. 41% of these patients reported modest or severe pain (using the OKS) at final follow-up. A combined endpoint including revision, poor function and significant pain drastically reduced the survival rate for the operation. Survival based on revision alone provides an acceptable but inaccurate impression of outcome in younger TKR patients (under 60years). A true representation of the success of TKR should include pain and function as endpoints.

Biomechanical analysis of posteromedial tibial plateau split fracture fixation - Corrected Proof

Zhi-Min Zeng, Cong-Feng Luo, Sven Putnis, Bing-Fang Zeng — 2010-02-01

Abstract: The purpose of this study was to compare the biomechanical strength of four different fixation methods for a posteromedial tibial plateau split fracture. Twenty-eight tibial plateau fractures were simulated using right-sided synthetic tibiae models. Each fracture model was randomly instrumented with one of the four following constructs, anteroposterior lag-screws, an anteromedial limited contact dynamic compression plate (LC-DCP), a lateral locking plate, or a posterior T-shaped buttress plate. Vertical subsidence of the posteromedial fragment was measured from 500N to 1500N during biomechanical testing, the maximum load to failure was also determined.It was found that the posterior T-shaped buttress plate allowed the least subsidence of the posteromedial fragment and produced the highest mean failure load than each of the other three constructs (P=0.00). There was no statistical significant difference between using lag screws or an anteromedial LC-DCP construct for the vertical subsidence at a 1500N load and the load to failure (P>0.05).This study showed that a posterior-based buttress technique is biomechanically the most stable in-vitro fixation method for posteromedial split tibial plateau fractures, with AP screws and anteromedial-based LC-DCP are not as stable for this type of fracture.

A multiple-bundle model to characterize the mechanical behavior of the cruciate ligaments - Corrected Proof

Shahram Amiri, T. Derek V. Cooke, Urs P. Wyss — 2010-01-29

Abstract: Measurements of elongations of the cruciate ligaments have been used to study the behaviors of these ligaments in-vitro and in-vivo, mostly based on simplified two-bundle models of the cruciates. The complex fiber anatomy of the cruciates may suggest a complex deformation behavior across the continuum of their substance that cannot be captured by only two measurement points. In this study, a new methodology was introduced to include more detailed fiber anatomy and to take into consideration the wrapping of the PCL around the intercondylar notch of the femur in deep flexion. The method was used in comparison to the conventional two-bundle models on three sample cadaver knees that underwent a passive flexion up to 150°. The elongation ratios of the bundles were measured as the ratio of change in the length of the bundles over their lengths at 0° flexion. The multiple-bundle models showed ranges of variations across the attachment sites of the cruciates which at all flexion angles were significantly larger than those observed from the conventional two-bundle models. When expressed in percentages, at 150° flexion the ranges of variations in the elongation ratio of the bundles were 32.7%±31.9% and 34%±8.6% for the ACL and PCL, respectively. Results of this study showed that important variations of elongation across the body of the cruciates can be obscured to the conventional two-bundle model of the cruciates, and therefore a more detailed bundle configuration is suggested for the purpose of studying elongation behaviors of these ligaments.

Effect of voluntary soft tissue tension and articular conformity after total knee arthroplasty on in vivo anteroposterior displacement - Corrected Proof

Y. Ishii, H. Noguchi, M. Takeda, H. Kiga, S.I. Toyabe — 2010-01-21

Abstract: The in vivo relationship between the degree of voluntary soft tissue tension and articular conformity after total knee arthroplasty (TKA) and anteroposterior (AP) displacement was simultaneously investigated by analyzing LCS prostheses (posterior cruciate ligament-sacrificing rotating platform design) in 20 knees from 20 patients. AP displacement was measured using the KT-2000 arthrometer, at 30° and 75° flexion, while patients were conscious and under anesthesia; 30° flexion was regarded as high conformity and 75° as low conformity. Mean displacements at 30° and 75° were 5.1mm and 7.0mm, respectively, in conscious patients, and 6.7mm and 7.7mm, respectively, in patients under anesthesia. AP displacement was significantly associated with soft tissue tension (p=0.026) and conformity (p=0.001). No interaction was observed between the two variables (p=0.193). Surgeons should recognize that AP displacement is greater in anesthetized patients than in conscious patients, regardless of the degree of conformity, and that higher conformity shows less displacement, regardless of the degree of soft tissue tension. These results may help surgeons to determine the intra-operative AP displacement required for proper postoperative displacement in the current prosthetic design.

Fibrin concentration affects ACL fibroblast proliferation and collagen synthesis - Corrected Proof

Patrick Vavken, Shilpa M. Joshi, Martha M. Murray — 2010-01-18

Abstract: Fibrin is a frequently used biomaterial in surgery and tissue engineering. While it has been shown that fibrin supports cellular proliferation and biosynthesis, there is a scarcity of studies focusing on the effects of fibrin concentration. The objective of this study is to assess the effect of fibrin concentrations around the physiological concentration of 3mg/ml on the behavior of ligament fibroblasts. Fibroblasts were obtained from the anterior cruciate ligaments of four pigs and seeded throughout fibrin gels of either 1, 3, or 6mg/ml fibrin. The gels were collected at 2, 6, and 10days for measurement of DNA and collagen content. We found that both DNA and collagen content increased significantly over time in gels made with all concentrations of fibrin. However, the increases were significantly lower in gels made with the higher concentrations of fibrin (3 and 6mg/ml). Microscopic assessment of FITC-labeled gels showed a decrease in pore size at high fibrin concentrations, which might be a reason for the observed effect on bioactivity. To enhance cell behavior and thus clinical results fibrin applications should build on physiologic or sub-physiologic concentrations, and those with higher concentrations, such as currently available sealants, should be used cautiously.

The role of the cemented all-polyethylene tibial component in total knee replacement: A 30-year patient follow-up and review of the literature - Corrected Proof

Thomas J. Blumenfeld, Richard D. Scott — 2010-01-11

Abstract: Use of an all-polyethylene tibial component in primary total knee arthroplasty remains an attractive option considering the reported durability of the construct, the lowered cost compared to modular metal-backed tibia, and the elimination of backside wear. The two major intra-operative disadvantages include the inability to alter the tibial component thickness after permanent implant placement and the inability to use varus-valgus constrained designs. The long-term disadvantage is the inability to perform a modular insert exchange should this be required. We report the 30-year outcome of a single patient using the duopatellar total knee replacement system. Based on a critical review of the literature we would recommend use in patients 80years of age or older, consideration in patients 75 to 79years, and possibly in younger yet less active patients. These three groups would be the least likely to require a modular tibial liner exchange in their lifetime.

Optimized functional femoral rotation in navigated total knee arthroplasty considering ligament tension - Corrected Proof

2010-01-11

Abstract: Femoral malrotation in total knee arthroplasty is correlated to an increased number of revisions. Anatomic landmarks such as Whiteside line, posterior condyle axis and transepicondylar axis are used for determining femoral component rotation. The femoral rotation achieved with the anatomical landmarks is compared to the femoral rotation achieved by a navigated ligament tension-based tibia-first technique.Ninety-three consecutive patients with gonarthritis were prospectively enrolled. Intraoperatively the anatomical landmarks for femoral rotation and the achieved femoral rotation using a navigated tension-based tibia-first technique were determined and stored for further comparison. A pre- and postoperative functional diagram displaying the extension and flexion and varus or valgus positions was also part of the evaluation.Using anatomical landmarks the rotational errors ranged from 12.2° of internal rotation to 15.5° of external rotation from parallel to the tibial resection surface at 90° flexion. A statistical significant improved femoral rotation was achieved using the ligament tension-based method with a rotational error ranged from 3.0° of internal rotation to 2.4° of external rotation. The functional analyses demonstrated statistical significant lower varus/valgus deviations within the flexion range and an improved maximum varus deviation at 90° flexion using the ligament tension-based method.Compared to the anatomical landmarks a balanced, almost parallel flexion gap was achieved using a navigation technique taking the ligament tension of the knee joint into account. As a result the improved femoral rotation was demonstrated by the functional evaluation. Unilateral overloading of the polyethylene inlay and unilateral instability can thus be avoided.

Congenital bony fusion (absence) of the knee: A case report - Corrected Proof

2010-01-11

Abstract: Congenital knee ankylosis is a rare condition which might be accompanied with other abnormalities or not. To our knowledge, there is no report on true bony ankylosis of the knee. The only ones in the literature include fibrous knee ankylosis. Thus this seems to be the first presentation of true congenital bony fusion of the knee joint.

The effects of applying adhesion prevention gel on the range of motion and pain after TKA - Corrected Proof

Chae-Gwan Kong, Yong In, Hyun-Min Cho, Kyung-Hwan Suhl — 2010-01-11

Abstract: A mixed solution of sodium hyaluronate and sodium carboxymethylcellulose (HA/CMC) has been shown to be effective for decreasing postoperative adhesions in various kinds of surgeries. We evaluated the clinical efficacy and safety of HA/CMC gel on the early postoperative range of motion and pain relief after total knee arthroplasty (TKA). Thirty one patients who underwent bilateral TKA as a single-stage procedure for primary osteoarthritis were included in the study. At the completion of surgery, among both knees, the HA/CMC gel was applied to one knee (the HA/CMC group) and HA/CMC gel was not applied to the other knee (the control group). The primary outcome measure was the early assessment of range of motion and the secondary outcome measures were the VAS pain scores and the number of complications in each group. Periarticular application of HA/CMC gel was safe without causing any wound problems or infection. However, local application of HA/CMC gel neither increased the range of motion nor reduced the pain during the early postoperative period of TKA.

Histological evaluation and comparison of the anteromedial and posterolateral bundle of the human anterior cruciate ligament of the osteoarthritic knee joint - Corrected Proof

Arata Watanabe, Akihiro Kanamori, Kotaro Ikeda, Naoyuki Ochiai — 2010-01-11

Abstract: A human anterior cruciate ligament (ACL) is composed of an anteromedial (AM) and posterolateral (PL) bundle which have different biomechanical functions. ACL degeneration and ACL deficiency often occur in patients with osteoarthritis (OA); however, histological evaluation of each bundle of the ACL in the OA knee has not been reported. Our objective was to compare the degenerative changes of the AM and PL bundle in the OA knee based on histological appearance. A histological evaluation of the AM and PL bundle from 49 varus OA knees was performed. Fifty-three percent of the AM bundle and 78% of the PL bundle showed severe histological degenerative changes. The degenerative changes were statistically more severe in the PL bundles than the AM bundles (p<0.05). Since the cross sectional area of the AM bundle is larger than that of the PL bundle and the pattern of length change of the PL bundle is greater than that of the AM bundle, it would logically follow that the PL bundle would show more severe degenerative changes than the AM bundle. This study identified the histological appearance of the bundles of the ACL of the OA knee and may help to elucidate the process of ACL degeneration in the OA knee.

The accuracy of acquisition of an imageless computer-assisted system and its implication for knee arthroplasty - Corrected Proof

S. Lustig, C. Fleury, D. Goy, P. Neyret, S.T. Donell — 2010-01-11

Abstract: The majority of the current computer-assisted systems (CAS) for knee prosthetic surgery require the acquisition of points using a tracker detected by an infrared camera. Two types of measurements are then essential: angles and distances. The goal of this study was to evaluate the accuracy of the data obtained during computer-assisted surgery using an in vitro protocol.Two models were developed to locate precisely both points (120 acquisitions) and distance measurements (144 acquisitions) and angles (170 acquisitions) with an image-free CAS using an infrared optical camera. For validation, a precise coordinate 3D measurement device was used to assess the accuracy of CAS acquisitions.The points, distances and angles had a mean error respectively of 0.638mm (0.244mm to 0.931mm), 0.355mm (0.001mm to 1.338mm) and 0.39° (0.06° to 0.69°). For all these acquisitions, the mean error was statistically less than 1mm or 1° (p<0.001).By using a 3D measurement system, it was possible to determine the accuracy of the data obtained with the navigation system. The precision assessed at less than 1mm or 1° corresponds with the accuracy needed in knee arthroplasty and with the use of CAS as a measurement tool. Variability in computer-assisted navigation may be more likely related to other aspects of the procedure such as bony landmark acquisition, tolerance of saw blades and cutting jigs than the accuracy of the imageless CAS itself.

Multi-ligament instability after early dislocation of a primary total knee replacement — Case report - Corrected Proof

Krisztian Sisak, John Lloyd, Nick Fiddian — 2010-01-05

Abstract: Peripheral nerve blocks have found increased popularity in providing prolonged post-operative analgesia following total knee replacement surgery. They generally provide effective analgesia with fewer complications than epidurals.This report describes an acute low-energy knee dislocation after a well balanced, fixed bearing, cruciate-retaining primary total knee replacement performed under a spinal anaesthetic with combined complimentary femoral and sciatic nerve blocks. The dislocation was not accompanied by neurovascular compromise. Due to the subsequent instability and injury to both collaterals, the posterior cruciate ligament and posterolateral corner structures, the knee was treated with a rotating-hinge revision total knee replacement.The dislocation occurred whilst the peripheral nerve blocks (PNB) were still working. We review our incidence of PNB related complications and conclude that PNB remain a safe and effective analgesia for total knee replacements. However, we advocate that ward staff and patients should be sufficiently educated to ensure that unaided post-operative mobilisation is prevented until such a time that patients have regained complete voluntary muscle control.

The potential of stem cells in the treatment of knee cartilage defects - Corrected Proof

Wasim S. Khan, David S. Johnson, Timothy E. Hardingham — 2010-01-05

Abstract: Cartilage is frequently damaged but only shows a limited capacity for repair. There are a number of treatment strategies currently available for the repair of articular cartilage defects including abrasion chondroplasty, subchondral drilling, microfracture and mosaicplasty but these show variable results. For the younger patients, there is great interest in the potential of cell-based strategies to provide a biological replacement of damaged cartilage using autologous chondrocytes. The results of clinical studies using these cell-based techniques do not conclusively show improvement over conventional techniques. These techniques also do not consistently result in the formation of the desired hyaline cartilage rather than fibrocartilage. Mesenchymal stem cells present a promising cell source for cartilage repair. Mesenchymal stem cells have been isolated from a number of adult tissues including the bone marrow and the synovial fat pad. These cells have the ability to proliferate in culture and differentiate down different pathways including the chondrogenic pathway. In the first instance, differentiated stem cells can be used for the repair of localised cartilage defects by producing hyaline cartilage. In the future, this strategy has the potential to be extended to treat more generalised cartilage defects, especially as the cell source is not a limiting factor. The use of cell-based therapies also allows the versatility of using scaffolds and growth factors, with recombinant proteins or gene therapy. A number of challenges however still need to be overcome including further work on identifying the optimal source of stem cells, along with refining the conditions that enhance expansion and chondrogenesis.

Custom-made lateral femoral condyle replacement for traumatic bone loss: A case report - Corrected Proof

B. Rose, W. Bartlett, G. Blunn, T. Briggs, S. Cannon — 2009-12-18

Abstract: We report the case of a 24year-old patient who underwent a novel treatment for a lateral femoral condyle fracture. The fracture was associated with extensive joint line depression and not considered suitable for conventional fixation techniques. Existing reconstructive options for such situations include unicondylar osteoarticular allograft, arthrodesis and arthroplasty. However, these techniques all present significant disadvantages, particularly in the management of active patients. We report our medium-term results following reconstruction using a custom-made lateral femoral condyle hemiarthroplasty replacement. Follow-up at 48months revealed an excellent, pain-free level of function, with an Oxford Knee Score of 46/48, a Knee Society knee score of 87/100 and a functional score of 100/100. Radiographs demonstrated no evidence of prosthesis loosening or migration and no erosion of the lateral tibial plateau. The technique allows preservation of the remaining normal joint surface of the femur that may promote earlier and better restoration of function. Furthermore, the isolated condyle hemi-replacement maximises bone preservation, facilitating future anticipated revisions. The procedure presents an attractive alternative to other surgical options and their attendant problems. Further investigation into this technique is required before widespread adoption, though such studies will be compromised by the relative rarity of patients in whom the technique is indicated.

Femoral fixation pattern in cemented Oxford unicompartmental knee arthroplasty — An experimental cadaver study - Corrected Proof

M. Clarius, G. Mohr, S. Jaeger, J.B. Seeger, R.G. Bitsch — 2009-12-15

Abstract: Femoral component loosening is a rare but serious complication in cemented Oxford unicompartmental knee arthroplasty (OUKA). In a cadaver study, OUKA was performed in 24 knees to evaluate the femoral fixation pattern. Due to the geometry of bone and implant, three different zones were identified. Complete cement mantles and good interdigitation were found in the spherical part of the implant (zone 1) and around the peg (zone 3), which implies that these are most important for implant fixation. The posterior plane facet (zone 2) is the weak point of the interface due to incompleteness of the cement mantle and a lack of interdigitation. This study suggests that the cancellous bone in zone 2 and the drill holes in sclerotic bone areas should be filled with cement and pressurised prior to component seating.

Custom-made hinged spacers in revision knee surgery for patients with infection, bone loss and instability - Corrected Proof

2009-12-09

Abstract: Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion. We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The “SMILES spacer” was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38months (range 24–70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients. In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation.

Long term outcome following knee replacement in patients with juvenile idiopathic arthritis - Corrected Proof

Ajay Malviya, Helen E. Foster, Peter Avery, David J. Weir, David J. Deehan — 2009-12-07

Abstract: Juvenile idiopathic arthritis (JIA) is a disabling and destructive condition that commonly affects the knee during childhood. Our study aimed to look at the outcome of knee replacement in this uncommon group, set a benchmark for survival and determine predictors of functional results.Patients were identified from a regional specialist rheumatology clinic set up for the care of adult patients with JIA. Outcome was assessed using Stanford HAQ 20-item disability scale, patient administered WOMAC questionnaire and Knee society score.This retrospective cohort includes 34 knee replacements in 20 patients with JIA performed at a median age of 35years with median follow up of 16years. Median WOMAC and Knee society score at last follow up were 61.7 and 60.8 respectively. The pain component of the scores was significantly (p<0.001) better than functional component. Strong negative correlation (R=−0.79, p<0.001) was noted between Knee society function score and HAQ score. Moderate negative correlation (R=−0.42; p=0.02) was noted between Knee society function score and age at onset of the disease. Multiple stepwise regression analysis to estimate the predictors of functional results showed that the only significant (p<0.001) predictor for functional outcome was disease activity, as predicted by the HAQ score. Kaplan Meier survival analysis revealed an estimated survival of 58.5% at 20years.Knee replacement is a satisfactory pain relieving procedure in JIA patients, although survival may be poor. Disease activity as determined by HAQ score, may predict functional results.

Influence of posterior condylar offset on knee flexion after cruciate-sacrificing mobile-bearing total knee replacement: A prospective analysis of 410 consecutive cases - Corrected Proof

T. Bauer, D. Biau, M. Colmar, X. Poux, P. Hardy, A. Lortat-Jacob — 2009-12-03

Abstract: The range of motion of the knee joint after Total Knee Replacement (TKR) is a factor of great importance that determines the postoperative function of patients. Much enthusiasm has been recently directed towards the posterior condylar offset with some authors reporting increasing postoperative knee flexion with increasing posterior condylar offset and others who did not report any significant association. Patients undergoing primary total knee replacement were included in a prospective multicentre study and the effect of the posterior condylar offset on the postoperative knee flexion was assessed after adjusting for known influential factors. All knees were implanted by three senior orthopedist surgeons with the same cemented cruciate-sacrificing mobile-bearing implant and with identical surgical technique. Clinical data, active knee flexion and posterior condylar offset were recorded preoperatively and postoperatively at a minimal one year follow-up for all patients. Univariate and multivariate linear models were fitted to select independent predictors of the postoperative knee flexion.Four hundred and ten consecutive total knee replacements (379 patients) were included in the study. The mean preoperative knee flexion was 112°. The mean condylar offset was 28.3mm preoperatively and 29.4mm postoperatively. The mean postoperative knee flexion was 108°. No correlation was found between the posterior condylar offset or the tibial slope and the postoperative knee flexion. The most significant predictive factor for postoperative flexion after posterior-stabilized TKR without PCL retention was the preoperative range of flexion, with a linear effect.

Late recurrent hemarthrosis following knee arthroplasty associated with epithelioid angiosarcoma of bone - Corrected Proof

M. Drexler, O. Dolkart, E. Amar, T. Pritsch, S. Dekel — 2009-11-30

Abstract: We report a case of recurrent hemarthrosis 1year following total knee arthroplasty in a patient with no bleeding diathesis, the hemarthrosis was found to be related to, and led to the diagnosis of high grade sarcoma of the proximal tibia. Twenty five years earlier, he sustained a lateral tibial plateau fracture and was treated with open reduction and plating. Sarcoma developing in association with a metallic orthopedic prosthesis or hardware is an uncommon, but well-recognized complication. Sarcomas that occur adjacent to orthopaedic prostheses or hardware are of varied types, but are usually osteosarcoma or malignant fibrous histiocytoma.

Peri-articular fractures of the knee: An update on current issues - Corrected Proof

Ravi Mallina, Nikolaos K. Kanakaris, Peter V. Giannoudis — 2009-11-30

Abstract: Peri-articular fractures of the knee in the young and elderly pose several management dilemmas. Over the last decade enormous interest has been generated in various fixation modalities, none proving to be an ideal stabilisation method. The problem is compounded by a lack of well-designed studies comparing various treatment options. In this article, the issues surrounding the diagnostic and management strategies of peri-articular fractures of the knee are discussed.

Intraarticular nodular fasciitis causing limitation of knee extension: A case report - Corrected Proof

2009-11-30

Abstract: We report a patient with intraarticular nodular fasciitis who developed mechanical symptoms in the knee, limiting knee extension. A 24year-old man presented with mechanical restriction of extension and pain at maximum extension. MRI revealed an intraarticular mass within the knee joint. The mass was excised arthroscopically. Histological examination of the excised tissue led to a diagnosis of nodular fasciitis. Pain and limitation of motion of the knee disappeared from one day after surgery. No recurrence was found after 1year. Intraarticular nodular fasciitis is rare, and although this lesion within the knee has been reported previously, it has not been associated with mechanical symptoms. This case indicates that intra-articular fasciitis should be considered in the differential diagnosis of a patient presenting with mechanical limitation of knee extension and a mass lesion inside the knee joint.

Accuracy of implantation during computer-assisted minimally invasive Oxford unicompartmental knee arthroplasty: A comparison with a conventional instrumented technique - Corrected Proof

Kwang Am Jung, Sung Jae Kim, Su Chan Lee, Seung Hyun Hwang, Nong Kyoum Ahn — 2009-11-30

Abstract: The prognosis of unicompartmental knee arthroplasty (UKA) is strongly associated with the accuracy of the component alignment. To determine the accuracy of navigated UKA during primary minimally invasive Oxford UKA, twenty-nine knees of 29 consecutive patients (Group A) implanted using conventional instrumented UKA were followed by 23 knees of 17 consecutive patients (Group B) implanted by navigation assisted UKA and radiological results regarding alignments of the femorotibial mechanical axis, femur, and tibial component were compared in the two groups. Assessments of mechanical limb alignment revealed statistically significant increases in mechanical limb alignment post-operatively in both groups (p=0.0 for both). In terms of component alignment, Group B had more prostheses implanted in the satisfactory range (>±3° from the targeted values) for the femoral and tibial components than Group A. There were no significant differences in the rate of prosthesis implanted within the range of radiographic alignment variations for the coronal implantation of either femoral or tibial components in both groups. (Radiographic alignment variation; coronal orientation of femoral components 90±10°, sagittal orientation of femoral components 90±5°, coronal orientation of tibial components from 10° varus to 5° valgus, sagittal orientation of tibial components from 7° of posterior tibial flexion to 5° of anterior tibial flexion). However, significant increases in the accuracies of sagittal implantation of femoral and tibial components were observed in Group B versus Group A. Our data suggest that navigated implantation improves the accuracy of the radiological implantation of the Oxford UKA prosthesis without increasing complications versus conventional UKA.

Posterior root tear of the medial meniscus in multiple knee ligament injuries - Corrected Proof

2009-11-18

Abstract: The purposes of the present study were to examine the frequency and characteristics of root tears of the medial meniscus associated with ligament injuries of the knee and to evaluate the effectiveness of pull-out repair for restoring meniscus function. We retrospectively analyzed the 9 patients (10 knees) with posterior root tears of the medial meniscus and ligament injuries of the knee treated between August 2004 and February 2007. All the patients were male, with average age of 29.8years, and the mean follow-up period was 29.7months. The pull-out suture technique was used to repair the root tears. Clinical outcomes were evaluated using the Lysholm, IKDC, and Tegner scores, as well as the McMurray and Apley tests. The mean follow-up period was 41.1months (range, 30 to 63months). The incidence of root tears of the medial meniscus with ligament injuries was 2.74% (10 cases in 365 ligament surgeries). All clinical results showed significant improvement. At the final follow-up, McMurray test showed one positive and nine negative cases, and the Apley test revealed two positive and eight negative cases. There were no positive findings in anterior drawer test, posterior drawer test, valgus and varus stress test, and posterolateral instability test. Healing of the root tear was confirmed by arthroscopy in five patients and by MR in four patients. Root tears of the medial meniscus may occur in multiple knee ligament injuries. It is important not to miss them. Our results indicate that pull-out repair provides satisfactory results and evidence of healing.

Mobile bearing dislocation in lateral unicompartmental knee replacement - Corrected Proof

2009-11-18

Abstract: Despite the theoretical advantages of mobile bearings for lateral unicompartmental replacement (UKR), the failure rate in the initial published series of lateral Oxford UKR's was unacceptably high. The main cause of failure was bearing dislocation. To address this problem we first modified the surgical technique and then introduced a new design with a convex domed tibial plateau. This paper presents the results of these changes.In the original series (n=53), implanted using a standard open approach, there were six dislocations, all of which occurred in the first year. Five of the dislocations were primary and one was secondary to trauma. In the second series (n=65), with the modified technique, there were three dislocations, all of which were primary and occurred in the second and third year. In the third series (n=101, 69 with a minimum 1-year follow-up), with the modified technique and the domed tibial plateau, there was one dislocation which was secondary to trauma and occurred in the second year. At 4years the dislocation rates in the three series were 11%, 5% and 1.7% and the primary dislocation rates were 10%, 5% and 0%. Both the overall and the primary dislocation rates were significantly different (p=0.04 and p=0.03) in the different series.The combination of the modified surgical technique and new design with a domed tibial component appears to have reduced the early dislocation rate to an acceptable level.

Effect of femoral to tibial varus mismatch on the contact area of unicondylar knee prostheses - Corrected Proof

Christian Diezi, Stephan Wirth, Dominik C. Meyer, Peter P. Koch — 2009-11-16

Abstract: In unicondylar knee prostheses, the relative angle and congruency of the femoral against the tibial component is not mechanically constrained and may vary with the surgical implantation technique.The contact area between both components was measured with increasing varus (0–20°) and flexion angles (−20° to 90°) in five prosthesis models in the laboratory.The contact area varied with the relative position of the components and was critically reduced up to 70% at a varus range between >5° and <25°.The importance of relative malpositioning of the femoral and tibial components may be underestimated and reduces the contact area of unicondylar prostheses decisively, independent from the limb axis. This increases local pressure and may thus importantly contribute to increased wear and early loosening.

Dynamic alignment and its association with knee adduction moment in medial knee osteoarthritis - Corrected Proof

2009-11-09

Abstract: Lower limb dynamic alignment represents the limb position during functional loading conditions and obtains valuable information throughout the gait cycle rather than a single instant in time. This study aims to determine whether dynamic alignment is altered in medial knee osteoarthritis (OA) and how dynamic alignment is related to knee adduction moment (KAM). Community-dwelling women (n=17) with medial OA in at least one knee, according to the American College of Rheumatology criteria and 17 body mass index-matched women without OA were recruited. A three-dimensional motion analysis system was used to collect the gait data at self-selected habitual and maximal speeds. Clinical evaluation of lower extremities, physical function, pain, habitual level of physical activity, quality of life and physical self-efficacy were assessed. Shank adduction angle and shank mean angular velocity were significantly greater in the OA group compared to the controls from heel strike to 30% stance. KAM was not different between the groups (p=0.542). Dynamic alignment variables were the best predictors of KAM. Health-related quality of life, habitual level of physical activity, lower extremity muscle strength and balance performance were impaired in the OA group compared to the controls. The importance of variables that contribute to dynamic alignment and the contribution of limb alignment to KAM were highlighted in this study. Detection of postural changes such as altered dynamic alignment in early stages of OA will lead to the institution of joint-protective measures including changes in footwear, orthotics, gait re-training, use of assistive devices to reduce weight-bearing loads, strengthening and balance enhancing exercises, better analgesia, or cartilage-preserving pharmacotherapy.

A lateral meniscus tear incarcerated behind the popliteus tendon: A case report - Corrected Proof

Mark S. Eskander, Jacob M. Drew, Daniel B. Osuch, Jeff Metzmaker — 2009-11-09

Abstract: A 51-year-old male, sustained an injury to his left knee after being pinned between his motorcycle and a road barrier. In the ER, the patient complained of medial knee pain, and had a significant joint effusion. MRI demonstrated an ACL injury, medial meniscal tear, bone bruising and impaction at the lateral femoral condyle and tibial plateau, and a tear of the posterior horn of the lateral meniscus that was displaced behind the popliteus. Unfortunately, the patient also presented with a deep vein thrombosis and thus could not proceed to the operating room for two months. During this time, scar tissue developed around the lateral meniscus.The purpose of this report is to present an unusual variant of a common injury pattern previously unreported where the posterior horn of the lateral meniscus became incarcerated behind the popliteus tendon and was left in place. It is likely that our patient will develop osteoarthritis in the future, but considering the circumstances he received a favorable early clinical outcome. Early recognition and a mobile fragment are essential restoring a patient's original anatomical features and achieving an optimal clinical outcome.

Salmonella infection of a total knee replacement - Corrected Proof

G.S. Carlile, J. Elvy, A.D. Toms — 2009-11-09

Abstract: Salmonella enterica serotype Choleraesuis is a rare infective pathogen in total knee arthroplasty and accounts for less than 1% of all cases. In the United Kingdom, the most prevalent organisms are Staphylococci, which account for over 50% of cases. We present an interesting case report of an infected revision total knee replacement following foreign travel to a region with an increased prevalence of Salmonella. The patient presented typically with an effused knee and raised inflammatory markers. Tissue samples demonstrated Salmonella choleraesuis as the infective organism. Though this serotype has previously been isolated from an infected total hip prosthesis, we believe this could be the first reported case involving a total knee replacement. Following involvement of our microbiology team and aggressive antibiotic therapy, the patient was successfully treated with two-stage revision surgery and at one-year post-op is making a satisfactory recovery.

Unusual mechanical complications of unicompartmental low contact stress mobile bearing patellofemoral arthroplasty: A cause for concern? - Corrected Proof

B.R.B. Arumilli, A.B.Y. Ng, D.J. Ellis, P. Hirst — 2009-11-09

Abstract: The Low Contact Stress Patellofemoral Arthroplasty (LCS PFA) is a newer design belonging to the second generation of inlay type implants, addressing the problems encountered in the first generation models (Lubinus & Richard's). The cemented mobile bearing metal backed patellar component in this system is “modular”; allowing interchangeable usage with either the trochlear component in a PFA or the femoral component of a total knee arthroplasty, thus obviating the need for patellar revision during conversion of PFA to TKA. The younger active patient with a PFA may exert extreme joint reaction forces on their patellar implant, rendering early loosening of the patellar implant. The endurance of this implant with repeated flexion beyond 90° is also a concern. We describe a series of three unusual mechanical failures associated with this particular design of metal backed patellar component of the unicompartmental LCS patellofemoral arthroplasty.

Skyline patellofemoral radiographs can only exclude late stage degenerative changes - Corrected Proof

2009-11-09

Abstract: Accurate preoperative assessment of the patellofemoral joint is especially important in compartment specific knee arthritis. This study aims to show the actual intraoperative grade of patellofemoral cartilage damage that may be reliably detected or excluded by preoperative standard radiographic views.100 consecutive knees awaiting arthroplasty underwent preoperative lateral and skyline radiographs and were scored using the Ahlback score. Intraoperative cartilage damage was assessed using the Collins score. The sensitivity and specificity were calculated for each grade of cartilage damage. Preoperative anterior knee pain and function were assessed and correlated to the degree of cartilage damage.The lateral radiograph shows poor sensitivity for all grades of disease (0.05–0.23). The skyline shows good sensitivity for grade 4 (large full thickness) damage (0.90) but decreases substantially for grades 1–3 (0.19–0.46). Significantly more people with skyline radiograph joint space narrowing complained of anterior knee pain than those with a normal radiograph (p<0.001). There was only a poor correlation between preoperative anterior pain and intraoperative patellofemoral cartilage damage (r=0.24).The lateral radiograph cannot exclude even large areas of full thickness cartilage damage whereas a normal skyline radiograph can reliably exclude significant (grade 4) patellofemoral disease and should be used in addition to the lateral view.

Three dimensional motion analysis of within and between day repeatability of tibial rotation during pivoting - Corrected Proof

2009-11-02

Abstract: Activities that involve a change in direction apply a high rotational load to the knee joint. Biomechanical analysis of such activities may be useful for determining mechanisms that underlie knee injury and the success of ligament reconstruction surgery. However, the reliability of the measurement of tibial rotation remains unclear. The purpose of this study was to determine the reliability of tibial rotation measurements during a pivoting task, both between testing sessions conducted on the same day and between those made one week apart. Three-dimensional motion analysis was used to measure peak internal tibial rotation and rotational excursion during a stair descent and pivoting task in eleven healthy subjects (six female, five males). Intraclass correlation coefficients (ICC (3, 1)) and typical error analyses were used to examine within and between day reliability. Tibial rotational excursion had excellent reliability for within day (ICC=0.82) and between day sessions (ICC=0.76) whereas peak internal rotation had good reliability (within ICC=0.74; between ICC=0.68). Typical error was less than 2.4° for within day measures and 2.9° for between day measures. It was concluded that tibial rotation can be measured reliably during pivoting. Typical error values were less than the usual group differences in rotational excursion reported in the literature. The ability to reliably quantify tibial rotation during dynamic activities is important in determining the causes of persisting instability following anterior cruciate ligament reconstruction.

Anterior knee pain and cold knees: A possible association in women - Corrected Proof

2009-11-02

Abstract: Abnormal reactions to environmental cold have been observed in some patients with Anterior Knee Pain (AKP). The aims of this study were to investigate whether palpation of the knee could classify patients into those with and those without cold knees; whether this classification could be objectively validated using thermal imaging; whether the cold and not cold knee groups varied in response to a cold stress test and in patient-reported measures. Fifty eight patients were recruited; palpation classified them into cold and not cold groups. Twenty-one (36%) patients were classified as having a cold knee by palpation: fourteen (36%) females and seven males (37%). Preliminary analysis suggested gender might be an effect modifier and the number of men was small, therefore the analysis focussed on females. Women with cold knees had a significantly smaller patellar skin fold, lower levels of activity and worse scores on the MFIQ, there also appeared to be an association with a traumatic onset. Women with cold knees were more likely to report cold weather affected their knees and they preferred a hot water bottle compared to an ice-pack on their knee; there was also a trend towards having to wear extra tights/long johns in the winter. This study has helped to define a clinical profile for a group of females with AKP and cold knees. This group appears to demonstrate a mild form of Reflex Sympathetic Dystrophy.

Aseptic versus septic revision total knee arthroplasty: Patient satisfaction, outcome and quality of life improvement - Corrected Proof

Nilesh Patil, Kevin Lee, James I. Huddleston, Alex HS Harris, Stuart B. Goodman — 2009-10-30

Abstract: We prospectively compared the clinical outcomes and patient satisfaction rates of aseptic (n=30) versus septic revision TKA (n=15) at a mean follow-up of 40months. We hypothesized that the clinical results of septic revision TKA would be inferior to aseptic revision TKA. The indication for revision in aseptic group was stiffness in 11 patients, aseptic loosening in 13, patellar loosening or maltracking in 6 patients. Patients operated for infection had better post-operative Knee Society Scores (KSS), Function Scores and SF-36 Mental Scores than aseptic group but there were no significant differences in the satisfaction rates. Patients operated for infection had more improvement in their KSS (p=0.004) and Function Scores (p=0.02) than patients revised for stiffness. Moreover, patients operated on for patellar problems had higher satisfaction rates than patients revised for stiffness (p=0.01) or aseptic loosening (p=0.01). Thus, patients undergoing septic revision TKA had better outcomes compared to those with aseptic revision TKA. However, in the aseptic group, revision TKA for stiffness was associated with the poorest outcomes. The indication for aseptic revision is an important variable when discussing treatment and outcome with patients.

Physical examination and in vivo kinematics in two posterior cruciate ligament retaining total knee arthroplasty designs - Corrected Proof

2009-10-30

Abstract: The aim of this study was to investigate anteroposterior instability in the CKS and the PFC total knee arthroplasty (TKA) designs. Physical examinations, including VAS, IKS and WOMAC were performed in combination with a detailed fluoroscopic measurement technique for three-dimensional kinematic assessment of TKA design function. Anteroposterior instability rated with the IKS was not significantly different (p=0.34), but patients with a CKS design showed more limitations according to the WOMAC joint stiffness total score, and for items regarding higher flexion activities in the WOMAC score for knee disability. Kinematic analyses showed that the CKS design tended to have more anterior sliding of the femur on the tibia during mid- and deep flexion activities. The sliding distance was larger at the medial than at the lateral side. This phenomenon has also been described for posterior cruciate ligament deficient knees. Furthermore, the CKS design showed a significantly lower range of tibial rotation (p<0.05) from maximum extension to maximum flexion during deep knee bend activities. Kinematic differences can be ascribed to posterior cruciate ligament deficiency/laxity or differences in TKA designs.

Conversion of lateral unicompartmental arthroplasty to anterior cruciate retaining tricompartmental knee arthroplasty - Corrected Proof

Lindsey Rolston, Christopher Moore — 2009-10-30

Abstract: This case report presents the conversion of a lateral unicompartmental arthroplasty (UKA) to an anterior cruciate retaining tricompartmental knee arthroplasty. The patient presented with disease progression to the medial and patellofemoral compartments of the knee, in addition to significant varus deformity. During revision surgery, the previously implanted UKA device was found to be well fixed and in good condition. The conventional treatment option would be conversion to total knee arthroplasty (TKA). However, in this case conversion to a tricompartmental, ligament sparing arthroplasty via implantation of a bicompartmental knee arthroplasty (BKA) device was found to be feasible. In UKA revision cases where the device is functional, the current surgical approach may be an appropriate alternative to conventional TKA.

Distal femoral resection at knee replacement — The effect of varying entry point and rotation on prosthesis position - Corrected Proof

Rajkumar Gangadharan, David J. Deehan, Andrew W. McCaskie — 2009-10-30

Abstract: Malalignment may contribute to early prosthesis failure through point loading and premature polyethylene wear. Femoral resection requires for distal planar resection contingent upon correct rotation and coronal alignment. Using a standard model, we have examined the influence of differing femoral entry points and rotations upon final femoral component positioning. A graphical method and navigation system independently quantified the individual and combined impact of these variables, in 3 planes. Nine permutations were assessed with reference to neutral rotation and a central entry point. The graphical results were corroborated by the navigation analyses. We found that external rotation and a superolateral entry point introduced the greatest error in final component positioning. We have identified a safe envelope for femoral rod positioning and recommend that the rotational alignment is determined before distal bone resection.

Increasing pre-activation of the quadriceps muscle protects the anterior cruciate ligament during the landing phase of a jump: An in vitro simulation - Corrected Proof

2009-10-28

Abstract: We hypothesize that application of an unopposed quadriceps force coupled with an impulsive ground reaction force may induce anterior cruciate ligament (ACL) injury. This situation is similar to landing from a jump if only the quadriceps muscle is active; an unlikely but presumably dangerous circumstance. The purpose of this study was to test our hypothesis using in vitro simulation of jump landing. A jump-landing simulator was utilized. Nine cadaveric knees were tested at an initial flexion angle of 20°. Each ACL was instrumented with a differential variable reluctance transducer (DVRT). Quadriceps pre-activation forces (QPFs) ranging from 25N to 700N were applied to each knee, followed by an impulsive ground reaction force produced by a carriage-mounted drop weight (7kg) that impulsively drove the ankle upward. ACL strain was monitored before landing due to application of QPF (pre-activation strain) and at landing due to application of the ground reaction force (landing strain). No ACLs were injured. Pre-activation strains exhibited a positive correlation with QPF (r=0.674, p<0.001) while landing strains showed a negative correlation (r=−0.235, p=0.032). Total ACL strain (pre-activation+landing strain) showed no correlation with QPF (r=0.023, p=0.428). Our findings indicate that elevated QPF increases pre-activation strain but reduces the landing strain and is therefore protective post-landing. Overall, there is a complete lack of correlation between “total” ACL strain and QPF suggesting that the total strain in the ACL is independent of the QPF under the simulated conditions.

Arthroscopic anterior cruciate ligament surgery: Results of autogenous patellar tendon graft versus the Leeds-Keio synthetic graft: Five year follow-up of a prospective randomised controlled trial - Corrected Proof

2009-10-27

Abstract: We conducted a prospective, randomised controlled trial comparing anterior cruciate ligament reconstruction using middle third patellar tendon graft (PT) to synthetic Leeds-Keio (LK) ligament. The patients were randomised (26 PT, 24 LK). Subjective knee function was classified (Lysholm, Tegner activity, IKDC scores), laxity was measured (Lachman test, Stryker laxometer), and functional ability was assessed (one-hop test).There were no significant differences between Lysholm or IKDC scores at any stage by 5years. Significant differences were found between the groups at 2years for Tegner activity scores, laxity and one-hop testing. By 5years there were no significant differences. Clinical equivalence was demonstrated between the two groups for the Lysholm score and one-hop test but not for the Tegner activity score at 5years.The use of the LK ligament has been largely abandoned due to reports of its insufficiency. Our results demonstrate that it is not as inferior as one might expect. We conclude that the results of LK ligament ACL reconstruction are as acceptable as those using PT. It may provide an additional means of reconstruction where no suitable alternative is present.

Matrix-assisted autologous chondrocyte implantation into a 14cm2 cartilage defect, caused by steroid-induced osteonecrosis - Corrected Proof

H. Clar, A. Pascher, N. Kastner, G. Gruber, T. Robl, R. Windhager — 2009-10-23

Abstract: Modern chemotherapy protocols have improved the prognosis for acute lymphoblastic leukaemia (ALL), one of the most common paediatric malignancies, but their high-dose corticosteroids lead to osteonecrosis in up to 9% of ALL patients. A 13.5-year-old female patient developed massive osteonecrosis of the right knee after successful ALL treatment. She presented at the age of 17.5years as a candidate for knee arthroplasty after conservative treatment had failed. Magnetic Resonance Imaging (MRI) revealed severe osteonecrosis, with the cartilage layer of the medial femoral condyle completely detached from the bone. We preferred to attempt a two-step biological reconstruction in this young patient, with arthroscopy of the right knee joint and removal of the dissected cartilage layer of the medial condyle. Matrix-assisted autologous chondrocyte implantation (MACI) was performed with harvested chondrocytes after imaging had indicated vital bone remodelling. Rehabilitation was according to MACI guidelines and after 5.5years, the patient shows continuous clinical improvement and is satisfied with the result. The Lysholm score improved from 45 to 99 and Tegner's activity score from 1 to 4. MRI follow-up showed a solid cartilage layer covering the medial condyle as a result of bone and chondral regeneration. Even if this approach had failed, bone remodelling would have still provided better conditions for knee arthroplasty.

In vitro stability of open wedge high tibial osteotomy with synthetic bone graft - Corrected Proof

2009-10-06

Abstract: It has been predicted that significant stress will be applied to the plate and lateral cortical hinge of an osteotomy site when early full weight bearing is commenced after an open wedge high tibial osteotomy. We hypothesized that the stress concentration on the plate or at the lateral cortical hinge would be reduced by inserting bone substitutes into the osteotomy gap. Two different types of tibia model were investigated: Group A, fixation with TomoFix with the osteotomy site left as an open space; and Group B, two β-TCP wedges are inserted into osteotomy site and fixed with TomoFix. Stress at five points was measured using strain gauges. Specimens were mounted onto a testing machine with an FTA (femoro-tibial angle) of 170°. Cyclic load tests and an ultimate load test were then performed. The mean stress on the plate was measured at 15.5±1.8Mpa in Group A. On the other hand, this value in Group B was only 9.52±2.1Mpa and this was a significant difference (P<0.01). The mean stress on the lateral hinge in Groups A and B was 3.31±0.5 and 2.49±0.2, respectively which was also a significant difference (P<0.05). The mean maximum breaking load in Group A was 2500±280N and in Group B 4270±420N which was a significant difference (P<0.01). Hence, for OWHTO procedures, the use of β-TCP wedges and TomoFix is thus likely to improve the initial axial and possibly rotational stability at the osteotomy site in comparison with methods that leave the osteotomy gap open.