The Knee - Articles in Press

Early complications of medial opening wedge high tibial osteotomy using autologous tricortical iliac bone graft and T-plate fixation - Corrected Proof

2010-09-01

Abstract: Despite several advantages of medial opening wedge high tibial osteotomy, this procedure has been noted to have a high rate of complications especially with the use of a spacer plate for fixation. We retrospectively evaluated the early complications of 138 medial opening wedge high tibial osteotomies done using autologous tricortical iliac bone graft and T-plate fixation(AO locking compression T-plate, Ti/3H 4.5–5.0mm, Synthes, Switzerland, Model No. 440.131 in 30 and low-profile locking T-plate and low-profile locking T-plate in 128 patients.At a mean follow-up of 36.8months (13 to 78), 26 knees (18.8%) developed complications. Complications varied from osteotomy site infection, loss of correction, broken screws and lateral tibial plateau fracture to joint fluid leakage, pseudoaneurysm and iliac bone fractures. Using the “safe zone” technique and penetrating the lateral cortex with Steinmann pins may help to avoid complications such as loss of correction and lateral tibial plateau fractures.The results of this study indicate that medial opening wedge high tibial osteotomy using autologous tricortical iliac bone graft and T-plate fixation may be a technically demanding procedure associated with a moderate rate of complications. However, these complications could be minimized with proper planning, adequate intra-operative precautions and few modifications to avoid technical error.

Preoperative proprioceptive training in patients with total knee arthroplasty - Corrected Proof

2010-08-30

Abstract: Proprioceptive deficiencies due to osteoarthritis and arthroplasty have been repeatedly reported. Proprioceptive training, which leads to an economisation of movements and supports energy-saving movement patterns, has become popular in athletes, but not in rehabilitation yet. The aim of this randomised phase IIb study was to evaluate whether preoperative proprioceptive training would influence postoperative balance and function in activities of daily life in patients undergoing total knee arthroplasty. Subjects with severe osteoarthritis of the knee scheduled for TKA were randomised to either a control group (CG) or a training group (TG). All patients were examined 6 weeks before and 6 weeks after TKA, patients of the TG also one day before surgery, i.e. after six weeks of preoperative proprioceptive training, in order to evaluate the influence of training without TKA. Evaluation included balance assessment using the Biodex Stability System, as well as measurements of gait speed and clinical outcome using the WOMAC and Knee Society Score. As opposed to the CG, stance stability improved significantly in the TG (Biodex OSI (p=0.045), APSI (p=0.029)) 6 weeks after TKA. There was a significant improvement in KSS, WOMAC pain and stiffness in both groups after TKA. Preoperative proprioceptive training in patients undergoing TKA resulted in improved standing balance, but no difference in clinical outcome was observed between the two groups.

Delayed intra-articular migration of the IntraFix outer sheath after anterior cruciate ligament reconstruction: A case report - Corrected Proof

Kee-Byung Lee, Si Young Song, Sang Hoon Paik, Won Hyoung Shin — 2010-08-30

Abstract: We describe a case of foreign body synovitis caused by delayed intra-articular migration of the outer sheath 5months after anterior cruciate ligament (ACL) reconstruction with a quadrupled tibialis allograft tendon using the IntraFix device for tibial fixation. The postoperative course was unremarkable. At 5months after surgery, the patient experienced a sudden catching sensation and a slight pain without any obvious twisting or trauma. At 6months after surgery, extension deficit was 20°. At arthroscopy, intra-articular migration of the outer sheath from the tibial tunnel and reactive synovitis were observed. The outer sheath in the joint and the inner screw in the tibial tunnel were removed successfully. The ACL graft was well incorporated under good tension. Patient was able to return to her previous level of all daily activities with no further episodes of swelling. To our knowledge, described here is the only case of foreign body synovitis due to intra-articular migration of the unbroken sheath.

Predicting dynamic knee joint load with clinical measures in people with medial knee osteoarthritis - Corrected Proof

Michael A. Hunt, Kim L. Bennell — 2010-08-30

Abstract: Knee joint loading, as measured by the knee adduction moment (KAM), has been implicated in the pathogenesis of knee osteoarthritis (OA). Given that the KAM can only currently be accurately measured in the laboratory setting with sophisticated and expensive equipment, its utility in the clinical setting is limited. This study aimed to determine the ability of a combination of four clinical measures to predict KAM values.Three-dimensional motion analysis was used to calculate the peak KAM at a self-selected walking speed in 47 consecutive individuals with medial compartment knee OA and varus malalignment. Clinical predictors included: body mass; tibial angle measured using an inclinometer; walking speed; and visually observed trunk lean toward the affected limb during the stance phase of walking. Multiple linear regression was performed to predict KAM magnitudes using the four clinical measures. A regression model including body mass (41% explained variance), tibial angle (17% explained variance), and walking speed (9% explained variance) explained a total of 67% of variance in the peak KAM.Our study demonstrates that a set of measures easily obtained in the clinical setting (body mass, tibial alignment, and walking speed) can help predict the KAM in people with medial knee OA. Identifying those patients who are more likely to experience high medial knee loads could assist clinicians in deciding whether load-modifying interventions may be appropriate for patients, whilst repeated assessment of joint load could provide a mechanism to monitor disease progression or success of treatment.

Human fetal anatomy of the posterior semimembranosus complex at the knee with special reference to the gastrocnemio-semimembranosus bursa - Corrected Proof

2010-08-27

Abstract: There is little information on the fetal anatomy of the posterior semimembranosus tendinous complex and its associated bursa. We examined histological sections (transverse or sagittal) of the right or left knee in 13 mid-term human fetuses (12–25weeks of gestation). The medial head of the gastrocnemius provided an aponeurosis facing or attached to the muscles of the pes anserinus by 12weeks of gestation. The peritendinous tissue of the semimembranosus provided a bursa continuous with a laterally extending plate-like tissue by 15weeks, but sometimes the typical bursa was absent. The aponeurosis of the medial head consistently accompanied a bursa-like space (false bursa) surrounded by heterogenous structures including the popliteus and a wall of the semimembranosus bursa. Sagittal sections displayed notches on the medial head surface that received the semimembranosus and semitendinosus overriding the medial head of the gastrocnemius. In contrast to a real bursa originating from the peritendinous tissue of the semimembranosus, a false bursa without a homogeneous wall consistently develops at the origin of the medial head of the gastrocnemius. Due to mechanical stress from the tendons, the false bursa is likely to develop into a structure similar to a real bursa with a synovial lining even if the real bursa is absent in the fetus. We hypothesize that the adult gastrocnemio-semimembranosus bursa, largely or partly, originates from the fetal false bursa. Absolute resection of the false bursa is difficult because it is a mere gap between normal tissues.

Investigating meniscal symptoms in patients with knee osteoarthritis—Is MRI an unnecessary investigation? - Corrected Proof

M.A. Kemp, K. Lang, M. Dahill, J.L. Williams — 2010-08-27

Abstract: The aim of this study was to evaluate the relationship between radiographic knee osteoarthritis and the presence of a relevant meniscal tear detected on MRI in symptomatic patients over the age of 60.Seventy seven patients over the age of 60 who had been investigated with a knee MRI over a 1-year period were identified. Sixty patients had a full set of data available for analysis. Their plain radiographs were blindly graded for osteoarthritis using the Kellgren–Lawrence (K–L) scale. The indications for the MRI were subdivided into: meniscal symptoms, general knee pain and “other”. These indications were correlated with the K–L grade and result of the MRI.Overall, 40% of patients with a K–L grade of 0 had a meniscal tear compared to 89% of patients with a K–L score of 3, and 88% with a K–L score of 4. The indications for an MRI were grouped into meniscal symptoms (49), general pain (6) and other (5). In the group investigated for meniscal symptoms, the incidence of meniscal tears was 92% and 100% with a K–L grade of 3 and 4 respectively. This equated to a positive predictive value of 93% for K–L grade 3 and above, and 100% for K–L grade 4 alone.Given the predictability of the MRI findings in patients with significant osteoarthritis as well as meniscal symptoms, we conclude that this is an unnecessary investigation when used for this indication.

Shod landing provides enhanced energy dissipation at the knee joint relative to barefoot landing from different heights - Corrected Proof

C.H. Yeow, P.V.S. Lee, J.C.H. Goh — 2010-08-27

Abstract: Athletic shoes can directly provide shock absorption at the foot due to its cushioning properties, however it remains unclear how these shoes may affect the level of energy dissipation contributed by the knee joint. This study sought to investigate biomechanical differences, in terms of knee kinematics, kinetics and energetics, between barefoot and shod landing from different heights. Twelve healthy male recreational athletes were recruited and instructed to perform double-leg landing from 0.3-m and 0.6-m heights in barefoot and shod conditions. The shoe model tested was Brooks Maximus II. Markers were placed on the subjects based on the Plug-in Gait Marker Set. Force-plates and motion-capture system were used to capture ground reaction force (GRF) and kinematics data respectively. 2×2-ANOVA (barefoot/shod condition×landing height) was performed to examine differences in knee kinematics, kinetics and energetics between barefoot and shod conditions from different landing heights. Peak GRF was not significantly different (p=0.732–0.824) between barefoot and shod conditions for both landing heights. Knee range-of-motion, flexion angular velocity, external knee flexion moment, and joint power and work were higher during shod landing (p<0.001 to p=0.007), compared to barefoot landing for both landing heights. No significant interactions (p=0.073–0.933) were found between landing height and barefoot/shod condition for the tested parameters. While the increase in landing height can elevate knee energetics independent of barefoot/shod conditions, we have also shown that the shod condition was able to augment the level of energy dissipation contributed by the knee joint, via the knee extensors, regardless of the tested landing heights.

Human anterior cruciate ligament fibroblasts from immature patients have a stronger in vitro response to platelet concentrates than those from mature individuals - Corrected Proof

Elise M. Magarian, Patrick Vavken, Martha M. Murray — 2010-08-23

Abstract: A number of recently published studies have established a substantial age dependence of the response of ACL fibroblasts to stimulation by platelet-rich plasma (PRP). Further in-depth research of this age dependence revealed negative effects on both histological and biomechanical results in a large animal model. However, while it has been postulated that this association could affect potential human applications negatively too it remains to be proven that the same effects occur in human cells. Thus it was the objective of this study to search for age dependence in human fibroblasts before further human experiments are done. Human fibroblasts were obtained from 10 immature and adolescent patients, based on a-priori power calculations, and cultured in a collagen-PRP composite. Three parameters that are pivotal for defect remodeling and wound healing—cell migration, cell proliferation, and scaffold contraction—were chosen as endpoints. Both migration and proliferation were significantly higher in immature cells, but no differences were seen in wound contraction. The former findings suggest that immature patients respond more favorably to treatment with PRP, which consequently might translate into better results in ACL tissue engineering.

A case for one-stage revision in infected total knee arthroplasty? - Corrected Proof

Richard W. Parkinson, Peter R. Kay, Arvind Rawal — 2010-08-19

Abstract: Infection in total knee replacement is a rare but devastating complication. The current literature tends to support a two-stage revision as definitive treatment of established deep infection. Despite the fact that single stage revision is a well recognised treatment for the infected hip replacement, it has not gained the same level of support in the knee.This article reviews the literature of two-stage and single stage revision and reports the senior author's experience with the latter.

Variations in dynamic knee valgus and gluteus medius onset timing in non-athletic females related to hormonal changes during the menstrual cycle - Corrected Proof

2010-08-19

Abstract: It has been suggested that activities of daily living could contribute to the occurrence of ACL injury in females. Currently, no studies have focused on the lower extremity behavior of a non-athletic population to compare or understand the lower extremity adeptness towards daily movements that mimic athletic tasks. Our hypothesis was that increased knee valgus angles would occur during the late follicular phase of the menstrual cycle accompanied by different onset timing of the gluteus medius muscle. In a controlled laboratory study, 23 non-athletic collegiate females participated and 15 subjects comprised the final sample for statistical analysis. Subjects performed a single leg drop landing maneuver while 3-D knee kinematics and gluteus medius muscle onset timing were assessed throughout three distinct phases of the menstrual cycle, confirmed by blood hormone analysis. In general, knee valgus angles were significantly less in the luteal phase compared to both follicular phases (p<0.005), while differences were not observed for gluteus medius onset timing (p=0.936). As a decreased knee joint valgus angle was observed during the luteal phase, it was hypothesized that the hormone progesterone could significantly influence knee kinematics during a dynamic task. However, such influence was not observed for gluteus medius EMG onset timing as a significant correlation between gluteus medius onset timing and knee valgus angle could not be determined.

Extracellular matrix content of ruptured anterior cruciate ligament tissue - Corrected Proof

Kate Young, Tom Samiric, Julian Feller, Jill Cook — 2010-08-19

Abstract: Anterior cruciate ligaments (ACLs) can rupture with simple movements, suggesting that structural changes in the ligament may reduce the loading capacity of the ligament. We aimed to investigate if proteoglycan and collagen levels were different between ruptured and non-ruptured ACLs. We also compared changes in ruptured tissue over time.During arthroscopic knee reconstruction surgery 24 ruptured ACLs were collected from participants (10 females; 14 males; mean age 24years). Four non-ruptured ACLs were obtained from participants undergoing total knee replacement surgery (one female, three males; mean age 66years). Western blot analysis was used to characterise core proteins of aggrecan, versican, decorin and biglycan and glycosaminoglycan assays were also conducted. Collagen levels were measured by hydroxyproline (OHPr) assays.Significantly lower levels of collagen, were found in ruptured ACL compared to non-ruptured ACL (p=0.004). Lower levels of both small and large proteoglycans were found in ruptured than non-ruptured ACLs. No correlation was found between time since rupture and proteoglycan or collagen levels.Ruptured ACLs had less collagen and proteoglycans than non-ruptured ACLs. These changes indicate either extracellular matrix protein levels were reduced prior to rupture or levels decreased immediately after rupture. It is possible that the composition and structure of ACLs that rupture are different to normal ACLs, potentially reducing the tissue's ability to withstand loading. An enhanced understanding of the aetiology of ACL injury could help identify individuals who may be predisposed to rupture.

What activities do patients with patellar instability perceive makes their patella unstable? - Corrected Proof

Toby O. Smith, Simon T. Donell, Rachel Chester, Allan Clark, Richard Stephenson — 2010-08-19

Abstract: Patellar instability is a disabling musculoskeletal condition. Whilst previous texts have suggested that twisting activities may cause patients to experience instability symptoms, no studies have assessed which activities are related to the patient's perceived instability. The purpose of this study was to determine which activities and with what frequency patients with patellar instability symptoms, perceive their patella to be unstable. Ninety patients referred because of recurrent patellar instability were asked to assess the frequency with which they perceived patellar instability for 19 everyday and sporting activities. The results indicated that sporting and multi-directional twisting activities were more frequently related to patellar instability symptoms, compared to lower energy, uni-planar activities. Females and those without a family history of patellar instability reported more frequent patellar instability symptoms, compared to males, or those with a family history of this disorder. Further study is now recommended to determine whether these results reflect that of patients with milder subluxation disorders, and whether factors such as hypermobility have an impact on perceived patellar instability for this patient group.

A case of anterior cruciate ligament tear accompanied by avulsion fractures of tibial tuberosity and Gerdy's tubercle - Corrected Proof

Jae Ho Yoo, Kang-Il Kim, Kyoung Ho Yoon — 2010-08-19

Abstract: A 54-year-old man visited our clinic due to a painful swelling of his right knee. He had attempted a forceful kick by his right leg during a Sepak Takraw-like sports activity, only to fail to hit the ball. He felt a popping sense on the knee and collapsed, even without direct trauma. Imaging studies revealed a disruption of the anterior cruciate ligament (ACL), and separate avulsion fractures of the tibial tuberosity and Gerdy's tubercle. The fractures were stabilized by two cancellous screws, respectively. The intra-operative fluoroscopy demonstrated a manifest ACL insufficiency. A simultaneous reconstruction of the ligament was not performed. At 6months after surgery, he had no difficulty in his activities of daily living. The involved knee joint was believed to have undergone a forceful pivot shift mechanism. Injuries to the ACL can be suspected from indirect signs on the radiologic images by a careful reconstitution of the injury mechanism and the associated lesions. Manifest osseous lesions on the plain radiographs can herald a major ligamentous injury and may be interpreted as an indirect sign of the ACL injury, which helps to establish a relevant management plan.

Reference axes for comparing the motion of knee replacements with the anatomic knee - Corrected Proof

P.S. Walker, Y. Heller, G. Yildirim, I. Immerman — 2010-08-19

Abstract: In the literature, different methods have been used to describe the motion of the anatomic knee and total knee replacements (TKR). The major goal of this study was to identify the most suitable methods for comparing TKR motion with that of the anatomic knee, whether for the purpose of developing new TKR designs, or evaluating existing ones. A further goal was to specify a testing methodology which would apply the methodology and represent a wide range of activities.Six knee specimens were tested in a Desktop Knee Machine, where different sequences of compressive, shear, and torque loads were applied at a full range of flexion angles. Data from a typical total knee was obtained by analysis. The motion results were displayed using different reference axes, specifically the circular axis, the epicondylar axis, the line joining the contact points, and the line joining the lowest lateral and medial femoral condylar points. It was concluded that the circular axis was the most generally applicable choice of a key femoral axis, for comparing the rigid body motion of a total knee with anatomic data, but that the actual contact points had important significance in full extension and in high flexion.

3D representation of the surface topography of normal and dysplastic trochlea using MRI - Corrected Proof

R. Biedert, A. Sigg, I. Gal, H. Gerber — 2010-08-19

Abstract: The three-dimensional (3D) image of the articular surface topography of the normal and the dysplastic trochlea has not been defined. The aim of this study was to represent both the normal and dysplastic trochlear geometry in 3D using magnetic resonance imaging (MRI). Using the segmentation software program Amira (Mercury Computer Systems, Inc., Chelmsford, USA) we created 3D reconstructions of the distal femur bone and cartilage using MRI scans. Bone and cartilage of the distal femur were traced slice by slice in the acquisitioned dimension while the Amira program reconstructed the 3D model. This model was then transferred to the Rhinoceros 4.0 software (Robert McNeel & Associates, Seattle, USA) for measuring. Using this system a non-invasive 3D representation of the articular cartilage and bone of the normal trochlea and depiction of different types of trochlear dysplasia were possible.Potential advantages of these MRI measurements are assessment of the 3D articular cartilage of the whole trochlea and the bony contours on the same image, no imaging errors from joint malpositioning, no ionizing radiation, precise preoperative planning according to the documented pathomorphology, and comparison between the preoperative and the postoperative shapes. The disadvantages include higher costs compared to radiography or CT scans, and time consuming reconstruction, making them currently a research tool.

An electromyographic exploratory study comparing the difference in the onset of hamstring and quadriceps contraction in patients with anterior knee pain - Corrected Proof

Sunit Patil, John Dixon, Lisa C. White, Alex P. Jones, Anthony C.W. Hui — 2010-08-19

Abstract: Idiopathic anterior knee pain in teenagers and young adults is a common condition. Patellar maltracking has been considered as a causative factor. The aim of our study was to investigate whether there was a difference in the timing of electromyographic (EMG) activity in the medial and lateral hamstring and quadriceps muscles of patients with anterior knee pain compared to asymptomatic control participants. This was a cross sectional observational study measuring EMG activation patterns. Two groups of participants were tested, one patient (mean age 15years, n=20) and one asymptomatic control (mean age 16years, n=17).Surface EMG (sampling rate 1000Hz) was recorded from vastus medialis obliqus, vastus lateralis, and the medial and lateral hamstrings during three repetitions of maximal voluntary isometric contractions. The relative timing of the medial and lateral quadriceps and hamstrings was evaluated.The mean (95% confidence interval) difference between the groups in the lateral–medial hamstring onset timing was 53.8(1.9 to 105.6)ms during the maximal contraction. An independent t test showed that this difference was statistically significant (p=0.043). The differences between the groups in the relative VMO to VL onset did not reach statistical significance.The results of this study suggest that the lateral hamstrings contract significantly earlier in patients with AKP compared to healthy controls for this small cohort. This altered activation pattern could produce external rotation of the tibia on the femur and cause lateral patella tracking.

Computer assisted knee arthrodesis in a primary case of septic arthritis: A case report - Corrected Proof

Rajesh N. Maniar, Jayesh V. Baviskar — 2010-08-19

Abstract: We report a case of a 78year old patient with primary septic arthritis who was treated with knee arthrodesis using computer navigation. Use of computer navigation avoided violating the medullary canal and its associated risks. Also, it offered the advantage of making precise bone cuts in all the three planes, thus minimizing the risk of malalignment. At 3months, our patient showed good appositional contact of the bone ends, stable fusion, with no sign of infection and was mobilized with a simple brace. At 6months review, the patient was walking painlessly without support. We achieved a mechanical axis alignment of 0° and 11° flexion as planned.

Functional analysis on the treatment of torn discoid lateral meniscus - Corrected Proof

To Wong, Ching-Jen Wang — 2010-08-09

Abstract: The purpose of this study is to evaluate the functional outcome on the treatment of torn discoid lateral meniscus. Thirty-two torn discoid lateral meniscuses in 29 patients were retrospectively reviewed. There were 13 males and 16 females with a mean age of 31.3±17.0. The age distribution were 24% in pediatric age (< 11years old), 38%in young adult under 25years and 38% in 25years and older. Subjective symptoms included pain in 63%, popping and snapping in 56%, locking in 41%, givingway in 17%; and objective signs included decreased knee motion in 16%. Partial lateral menisectomy and saucerization were performed in 18 knees (56%), meniscus repairs were done in eight knee (25% ) and subtotal lateral menisectomy in six knees (19%). At an average follow up of 52.5±25.9months (24-96months). The results showed 84% good to excellent, 16% fair, and none poor. No significant difference was noted on the outcomes of different treatment methods. The age of symptom onset and the time of operation correlated with the IKDC and Tenger score. (p<0.001). Our data showed symptomatic torn discoid lateral meniscus may manifest at any age from childhood to adult. The first manifestation of symptom before age 11year old was observed in only 24%. Therefore, discoid lateral meniscus should not be considered a childhood disease.

Evaluation of implant position and knee alignment after patient-specific unicompartmental knee arthroplasty - Corrected Proof

2010-08-05

Abstract: Implant positioning and knee alignment are two primary goals of successful unicompartmental knee arthroplasty. This prospective study outlines the radiographic results following 32 patient-specific unicompartmental medial resurfacing knee arthroplasties. By means of standardized pre- and postoperative radiographs of the knee in strictly AP and lateral view, AP weight bearing long leg images as well as preoperative CT-based planning drawings an analysis of implant positioning and leg axis correction was performed.The mean preoperative coronal femoro-tibial angle was corrected from 7° to 1° (p<0.001). The preoperative medial proximal tibial angle of 87° was corrected to 89° (p<0.001). The preoperative tibial slope of 5° could be maintained. The extent of the dorsal femoral cut was equivalent to the desired value of 5mm given by the CT-based planning guide. The mean accuracy of the tibial component fit was 0mm in antero-posterior and +1mm in medio-lateral projection. Patient-specific fixed bearing unicompartmental knee arthroplasty can restore leg axis reliably, obtain a medial proximal tibial angle of 90°, avoid an implant mal-positioning and ensure maximal tibial coverage.

Bilateral stress fracture of the femoral shaft after total knee arthroplasty: A case report - Corrected Proof

Hong Chul Lim, Ji Hoon Bae, Ju Won Yi, Jung Ho Park — 2010-08-02

Abstract: The authors present a case of bilateral stress fracture of the femoral shaft 15years after total knee arthroplasty. Considerable femoral bowing deformity and varus malposition of the femoral and tibial components after total knee arthroplasty may produce abnormal stresses and lead to stress fracture of the distal femur in the region of greatest curvature.

Stochastic resonance electrical stimulation to improve proprioception in knee osteoarthritis - Corrected Proof

2010-07-26

Abstract: Proprioceptive deficits occur with knee osteoarthritis (OA) and improving proprioception may slow joint degeneration by allowing more appropriate joint loading. Stochastic resonance (SR) stimulation improves balance and the sensitivity of specific mechanoreceptors. Our purpose was to evaluate the effects of SR electrical stimulation combined with a knee sleeve on proprioception in subjects with knee OA. Joint position sense (JPS) was measured in 38 subjects with knee OA during four conditions in both a partial weight-bearing (PWB) and non weight-bearing (NWB) task: no electrical stimulation/no sleeve, no electrical stimulation/sleeve, 50μA-RMS stimulation/sleeve, and 75μA-RMS stimulation/sleeve. Subjects also reported their knee pain, stiffness, functionality (WOMAC), and instability. Repeated measures ANOVA and Spearman correlations were performed to investigate differences between the conditions and relationships among the outcome measures. JPS during the 75μA-RMS stimulation/sleeve and sleeve alone conditions was significantly improved compared to the control condition in the PWB task. However, the 75μA-RMS stimulation/sleeve and the sleeve alone conditions did not differ from each other. A moderate correlation was found between the improvements with the 75μA-RMS stimulation/sleeve condition compared to the JPS of the control condition in the PWB task. No differences in JPS were found between the four conditions in the NWB task. Significant correlations were found between the control JPS and WOMAC indices (p<0.005). Improved proprioception during the PWB task was achieved with a sleeve alone and in combination with SR stimulation. The observed correlations suggest that subjects with larger proprioceptive deficits may benefit most from these therapies.

Muscle damage during minimally invasive surgical total knee arthroplasty traditional versus optimized subvastus approach - Corrected Proof

2010-07-23

Abstract: Decreased muscle damage is reported as an advantage of minimally invasive surgical (MIS) approaches in total knee arthroplasty (TKA). The purpose of this study was to evaluate the anatomy of vastus medialis obliquus (VMO) tendon at its patellar insertion as well as to determine the amount and location of muscle damage comparing traditional subvastus approach and optimized subvastus approach. TKAs were performed in ten human cadavers (20 knees). In each specimen, one knee underwent the traditional subvastus approach and the contralateral knee the optimized subvastus approach. The risk of tearing and damaging the VMO muscle during the traditional subvastus approach is significantly higher (70% of the cases) compared to the optimized technique (30%). The amount of damage to the VMO muscle using the traditional subvastus approach was: 80% of the muscle's width in two cases, 60% in three cases, and 30% in two. The damage created by the optimized subvastus approach occurred along the edge of the tendon and the first fibers of the VMO muscle close to the muscle–tendon junction (less than 20% of muscle's width). Clinical studies are needed to determine the functional implications of these findings.

Accounting for velocity of the pivot shift test manoeuvre decreases kinematic variability - Corrected Proof

2010-07-22

Abstract: The pivot shift test is the only clinical test which correlates with knee function following rupture of the ACL. A grade is given to the pivot shift in a subjective manner, leading to efforts to quantify the bone movements and correlate them to the grade. However, the dynamic and unconstrained nature of the manoeuvre introduces important kinematic variability.Our main objective was to develop a method to lessen the variability attributable to clinician technique, therefore increasing inter-grade differences.Three different orthopaedic surgeons each performed the pivot shift test on 12 subjects. Knee joint kinematics were recorded using electromagnetic motion capture devices. Inter-clinician variability was quantified and a method was developed to diminish it, using the angular velocity of flexion. This method was then applied to a larger population composed of 127 knees with various degrees of instability, evaluated by one of eight different orthopaedic surgeons.The clinical grades given by the clinicians were in almost perfect agreement (kappa=0.83). Normalization of kinematic parameters using the angular velocity of knee joint flexion produced by the clinicians reduced the intra-clinician variability by 20%, resulting in an intra-class correlation coefficient (ICC) of 0.52, up from 0.41 before normalization. This allowed for more significant differences between the grades of pivot shift.Simple normalisation of pivot shift kinematics using the angular velocity of flexion reduces clinician-related variability and allows for significant differences between the different grades. These results are an important step towards developing an objective measurement tool for the pivot shift phenomenon.

Reconstruction of a patellar tendon with Achilles tendon allograft for severe patellar infera — A case report - Corrected Proof

Je-Hyun Yoo, Jun-Dong Chang, Young-Jin Seo, Suk-Woo Baek — 2010-07-21

Abstract: Severe patellar infera accompanied by pathologic shortening and fibrosis of the patellar tendon is relatively an uncommmon condition but can cause recalcitrant joint stiffness and limited range of motion after knee surgery or injury. This report presents a case of a 49-year-old male with severe patellar infera and limping due to joint stiffness after three-time knee surgeries. We report a successful outcome along with a finding of the well-healed allograft after the reconstruction of a patellar tendon using Achilles tendon-bone allograft.

Successful treatment of wound breakdown caused by pyoderma gangrenosum after total knee arthroplasty - Corrected Proof

N. Nakajima, M. Ikeuchi, M. Izumi, M. Kuriyama, H. Nakajima, T. Tani — 2010-07-21

Abstract: Pyoderma gangrenosum is a rare ulcerative disorder of the skin of unknown etiology. We present a case of pyoderma gangrenosum that occurred following total knee arthroplasty, which was initially misdiagnosed as severe wound infection. Repeated debridement procedures resulted in a large soft tissue defect around the anterior knee joint. The patient was treated successfully with a latissimus dorsi musculocutaneous flap under immunosuppressive therapy. Pyoderma gangrenosum is often misdiagnosed as an infected wound, but the treatment for theses differential diagnoses is completely different. When a lesion is refractory to thorough treatment for infection, a diagnosis of pyoderma gangrenosum should be considered.

Non-linear flexion relationships of the knee with the hip and ankle, and their relative postures during landing - Corrected Proof

C.H. Yeow, P.V.S. Lee, J.C.H. Goh — 2010-07-20

Abstract: The knee joint, together with the hip and ankle, contributes to overall shock absorption through their respective flexion motions during landing. This study sought to investigate the presence of a lower extremity coordination pattern by determining mathematical relationships that associate knee flexion angles with hip flexion and ankle dorsiflexion angles during landing phase, and to determine relative postures of the hip and ankle, with reference to the knee, and examine how these relative postures change during key events of the landing phase. Eight healthy male subjects were recruited to perform double-leg landing from 0.6-m height. Motion capture system and force-plates were used to obtain kinematics and ground reaction forces (GRF) respectively. Non-linear regression analysis was employed to determine appropriate mathematical relationships of the hip flexion and ankle dorsiflexion angles with knee flexion angles during the landing phase. Relative lower extremity postures were compared between events of initial contact, peak GRF and maximum knee flexion, using ANOVA on ranks. Our results demonstrated a lower extremity coordination pattern, whereby the knee flexion angles had strong exponential (R2=0.92–0.99, p<0.001) and natural logarithmic (R2=0.85–0.97, p<0.001) relationships with hip flexion and ankle dorsiflexion angles respectively during the landing phase. Furthermore, we found that the subjects adopted distinctly different relative lower extremity postures (p<0.05) during peak GRF as compared to initial contact. These relative postures were further maintained till the end of the landing phase. The occurrence of these relative postures may be a reflexive mechanism for the subjects to efficiently absorb the impact imposed by the peak GRF.

Osteochondral autografts in full thickness patella cartilage lesions - Corrected Proof

2010-07-15

Abstract: The purpose of this study was to evaluate clinical, functional and imaging results of full thickness patella cartilage lesions treated with osteochondral autografts (OCA). We studied a consecutive case series of 10 patients. At follow-up, Lysholm and International Knee Documentation Committee (IKDC) scores were obtained. Magnetic resonance imaging (MRI) evaluation was performed at an average of 8months post-op. The average cartilage lesion area was 1.2cm2. An average of 1.9 grafts was used per patient. The average Lysholm scores were: pre-op 73.8±8.36; post-op 95±4.47 points (p<0.05). The average IKDC post-op score was 95±1.74 points. No postoperative complications were registered. In the MRI analysis we found that in all cases, OCA presented flush characteristics when compared with adjacent cartilage. The majority of cases presented no fissures in the graft–receptor interface (60%). In 80% we observed mild bone marrow edema around the graft. According to the International Cartilage Research Society (ICRS) cartilage lesions classification, all grafts were considered 1A; in the periphery cartilage was classified as 1A in 60%. We conclude that patellar OCA is a good alternative for the treatment of full thickness patellar cartilage lesions, offering good clinical, functional and imaging results at midterm follow-up.

Medial patellofemoral ligament reconstruction for subluxating patellofemoral arthroplasty - Corrected Proof

M.R. Carmont, T. Crane, P. Thompson, T. Spalding — 2010-07-09

Abstract: Patellofemoral joint (PFJ) arthroplasty has become a successful operation for patellofemoral osteoarthritis. The post-operative complication of patella subluxation is uncommon.We report the stabilisation of a subluxating patella following PFJ arthroplasty using autogenous hamstring tendons. Medial patellofemoral ligament reconstruction may be considered a method of stabilising a subluxating patellofemoral replacement in patients for whom revision arthroplasty is not recommended.

The prevalence of cognitive dysfunction after conventional and computer-assisted total knee replacement - Corrected Proof

H. Deo, G. West, C. Butcher, P. Lewis — 2010-07-08

Abstract: Post operative cognitive dysfunction (POCD) is common following lower limb arthroplasty. The prevalence varies from 41–75% at 7days to 18–45% at 3months post operatively. The wide range of prevalence is due to inconsistencies in defining and quantifying POCD.The aim of this study is to ascertain an accurate prevalence of POCD in patients who had either conventional TKR (n=31) or computer-assisted TKR (n=30).Cognition was assessed pre-operatively, 6days and at 6months post-operatively by a battery of 11 validated neuropsychological tests.We found the mean prevalence of POCD to be 72% at 6days and 30% at 6months post-operatively. When comparing the prevalence of POCD between the two groups, we found no statistically significant difference at 6days or at 6months post-operatively. The only statistically significant factor between the two groups was the mean procedure time which was longer in the computer-assisted TKR group (p=< 0.001). We found a correlation between procedure time and the prevalence of POCD at 6days (p=0.02) but not 6months (p=0.26).POCD occurs in approximately one-third of TKR patients at 6months post-operatively. The cause is undoubtedly multi-factorial; however we have demonstrated that procedure time may be a contributing factor. Our results suggest that using an intra-medullary femoral jig has no effect on POCD. Further research into the cognitive effects following TKR with and without a tourniquet would be of benefit.

Treatment of patellofemoral chondropathy with the Bandi tibial tubercle osteotomy: More than 10years follow-up - Corrected Proof

2010-07-07

Abstract: Isolated degenerative patellofemoral chondropathy is a prevalent disease. There is still controversy regarding its ideal type of management.A retrospective study was performed to assess the outcomes of 28 patients with a minimum of 10-year follow-up, in whom the Bandi tibial tubercle osteotomy was performed.The Bentley score was applied pre and postoperatively to evaluate the clinical results.Preoperatively, 21 (67%) patients were rated as fair and seven (33%) as poor according to the Bentley functional scale for patellofemoral osteoarthritis.At 5years of follow-up, one case was rated as excellent, 23 (81%) cases as good, three as fair and one as poor.At 10years of follow-up no cases were rated as excellent, 17 (61%) cases as good, four (14%) as fair and seven (25%) as poor. The difference in terms of poor results evaluated at five and 10years after the surgery was statistically significant (p<0.05).We concluded that excellent and good short-term results can be expected with the use of the Bandi tibial tubercle osteotomy in patients with isolated degenerative patellofemoral chondropathy; however, such outcomes tend to deteriorate over the time, especially in patients with advanced chondromalacia, making its indication controversial.

Delamination wear on two retrieved polyethylene inserts after gamma sterilization in nitrogen - Corrected Proof

J.-M. Brandt, J.B. Medley, S.J. MacDonald, R.B. Bourne — 2010-07-02

Abstract: Two self-aligning mobile bearing knee replacements (SAL-1) with gamma-in-nitrogen sterilized polyethylene inserts were revised due to instability after 6.3years and after 14.2years in vivo in two patients. The predominant damage features were burnishing, cracking, and delamination and were observed on the proximal bearing surface of the retrieved polyethylene inserts. This suggested an association with sub-surface fatigue, perhaps initiated by in vivo oxidative degradation which was confirmed by developing a sub-surface white band in one insert. The damage features observed on the distal bearing surface of the polyethylene inserts suggested both an adhesive wear mechanism and an abrasive wear mechanism. The titanium-nitrite coated, titanium-alloy tibial tray was severely worn in one case and possibly contributed to third-body abrasive wear at the distal surface interface. We suggest to carefully follow-up patients who received this type of mobile bearing knee system.

Treatment of chronic disruption of the patellar tendon in Osteogenesis Imperfecta with allograft reconstruction - Corrected Proof

2010-07-01

Abstract: We present a case of chronic disruption of the patellar tendon in a patient with Osteogenesis Imperfecta. This patient was treated with a customized extensor mechanism allograft. Results were excellent at 5years follow up. To our knowledge this treatment has not previously been published in this situation. We present this as a reliable treatment option.

Treatment of osteoarthritis with infrapatellar fat pad derived mesenchymal stem cells in Rabbit - Corrected Proof

2010-06-30

Abstract: Osteoarthritis (OA) is a progressively debilitating disease that affects mostly cartilage, with associated changes in the bone. Increasing incidence of OA and the aging population coupled with insufficient therapeutic choices has led to focus on the potential of stem cells as a novel strategy for cartilage repair. In this study, we used scaffold free mesenchymal stem cells obtained from infrapatellar fat pad in an experimental animal model of OA by direct intraarticular injection. Mesenchymal stem cells isolated from a 2.8kg White New Zealand rabbit. The cells were expanded and grown in vitro. OA was induced by unilaterally anterior cruciate ligament transection of knee joints. Twelve weeks after operation, a single dose of 1million cells suspended in 1ml of medium was delivered to the injured knee by direct intraarticular injection. Control group received 1ml of medium without cells. The knees were examined after sixteen and twenty weeks from the surgery. Repairing was investigated radiologically, grossly and histologically using haematoxylin and eosin, Safranin-O and toluidine blue staining. Radiological assessment confirmed development of OA changes after 12weeks. Rabbits receiving mesenchymal stem cells showed lower degree of cartilage degeneration, osteophyte formation, and Subchondral sclerosis than control group at 20week after surgery. The quality of cartilage was significantly better in cell-treated group compared with control group after 20weeks. In conclusion, infrapatellar fat pad derived mesenchymal stem cells could be the promising cell sources for the treatment of OA.

Blood loss following total knee replacement in the morbidly obese: Effects of computer navigation - Corrected Proof

2010-06-30

Abstract: Computer navigated total knee arthroplasty (TKA) has several proposed benefits including reduced post-operative blood loss. We compared the total blood volume loss in a cohort of morbidly obese (BMI>40) patients undergoing computer navigated (n=30) or standard intramedullary techniques (n=30) with a cohort of matched patients with a BMI<30 also undergoing navigated (n=31) or standard TKA (n=31). Total body blood loss was calculated from body weight, height and haemotocrit change, using a model which accurately assesses true blood loss as was maximum allowable blood loss which represents the volume of blood that can be lost until a transfusion trigger is required. The groups were matched for age, gender, diagnosis and operative technique.The mean true blood volume loss across all BMI's was significantly (p<0.001) less in the computer assisted group (1014±312ml) compared to the conventional group (1287±330ml). Patients with a BMI>40 and a computer navigated procedure (1105±321ml) had a significantly lower (p<0.001) blood volume loss compared to those who underwent a conventional TKA (1399±330ml). There was no significant difference in the transfusion rate or those reaching the maximum allowable blood loss between groups.This study confirms a significant reduction in total body blood loss between computer assisted and conventional TKA in morbidly obese patients. However computer navigation did not affect the transfusion rate or those reaching the transfusion trigger in the morbidly obese group. Therefore computer navigation may reduce blood loss in the morbidly obese patient but this may not be clinically relevant to transfusion requirements as previously suggested.

Sensitivity of knee soft-tissues to surgical technique in total knee arthroplasty - Corrected Proof

2010-06-14

Abstract: Restricted range of motion and excessive laxity are both potential complications of total knee arthroplasty (TKA). During TKA surgery, the surgeon is frequently faced with the question of how tightly to implant the prosthesis. The most common method of altering implantation tightness is to vary the thickness of the polyethylene inlay after the bone cuts have been made and the trial components inserted. We have sought to quantify how altering the polyethylene thickness may affect post-operative soft tissue tension for a range of prosthetic designs.Four different prosthetic designs were implanted into fresh-frozen cadaveric knee joints. All four designs were implanted in the standard manner, with a 100 Newton distraction force used to set soft tissue balance. The tibiofemoral force was then recorded at 15° intervals throughout the passive flexion range. After the standard implantation of each prosthesis, the tibial component was raised or lowered to mimic increasing and decreasing the polyethylene thickness by 2mm and the force measurements repeated.Tibiofemoral force in extension correlated with implantation tightness for all prosthesis designs. Between 15° and 90°of knee flexion, all four designs were insensitive to changes in implantation tightness. Beyond 90° the effect was more notable in rotating platform mobile-bearing and cruciate-retaining prostheses than in posterior-stabilised mobile-bearing designs.The findings of this research may be useful in assisting surgical decision-making during the implantation of TKA prostheses.

An observational study on MR images of the effect of the discoid meniscus on articular cartilage thickness - Corrected Proof

David Babajide Oni, K Jeyapalan, Olusola O.A. Oni — 2010-06-09

Abstract: The discoid meniscus is known to affect the morphology and mechanics of the knee compartment in which it is housed. To determine whether it also is determinative of the articular cartilage thickness, measurements were made on MR images. There was no statistically significant difference in femoral or tibial articular cartilage thickness between compartments with normal meniscus and compartments with discoid meniscus. These findings suggest that mechanical disturbances wrought by the discoid shape do not have a ‘Wolff law’ effect.

Correlation of changes in pain intensity with synovial fluid adenosine triphosphate levels after treatment of patients with osteoarthritis of the knee with high-molecular-weight hyaluronic acid - Corrected Proof

2010-06-04

Abstract: We sought to determine whether a clinical association exists between osteoarthritis (OA)-associated knee pain and adenosine triphosphate (ATP) levels in synovial fluid (SF). A total of 28 patients with 28 primary OA knees were included. They routinely received intra-articular injection of high-molecular-weight hyaluronic acid (HA) once weekly for 5weeks (treated group). Eight patients without knee pain who had undergone an operation for anterior or posterior cruciate ligament reconstruction 2years ago were also examined (control group). SF and blood ATP concentrations, total amount of ATP, total SF volume, and Visual Analogue Scale (VAS) scores in all patients were measured and we compared pre-treatment values with those 1week after the final treatment. We evaluated the correlation of change in total ATP (ΔATP) and change in VAS score (ΔVAS), ΔVAS and change in SF volume (ΔSF), and ATP concentration in SF and blood. In the treated group, SF ATP concentration, total amount of ATP, SF volume, and VAS score were all significantly lower post-treatment than pre-treatment (p=0.0005, 0.0003, 0.0022, and <0.0001, respectively). In treated group, ΔVAS was significantly associated with ΔATP (r=0.56, p=0.0032), ΔSF was significantly associated with ΔVAS (r=0.78, p<0.0001), and total amount of SF ATP and SF volume at pre-treatment were significantly higher than the control group (p<0.0001, p<0.0001) We demonstrated an association between SF ATP level changes and OA knee pain, which should facilitate a further understanding of OA pain mechanisms.

Unicompartmental knee replacement for patients with partial thickness cartilage loss in the affected compartment - Corrected Proof

2010-06-03

Abstract: It is recommended that in medial compartment osteoarthritis (OA) unicompartmental knee replacement (UKR) should not be undertaken unless there is bone on bone. This recommendation is not evidence based and it is important to know if it is correct as there are many patients with pain and partial thickness cartilage loss (PTCL) who could potentially benefit from UKR. The aim of this study was to determine if the recommendation is valid.From our database of over 1000 patients treated with the Oxford UKR, we identified 29 with medial OA that had PTCL, confirmed at operation, but otherwise satisfied the recommended indications. This group was matched with 29 knees that had bone exposed (BE) on both sides of the medial compartment and 29 knees that had bone loss (BL) on both sides of the medial compartment. There was no significant difference in the demographics or preoperative scores between the three groups. At a mean follow up of 2years (range 1–6) the Oxford Knee Score (OKS) of the PTCL group (mean 36 SD 10) was significantly (p<0.001) worse than the OKS of either the bone exposed group (mean 43 SD 4) or the bone loss group (mean 43 SD 5). 21% of those with PTCL did not benefit substantially from the operation (increase in OKS≤6), whereas all patients in the other groups did.We conclude that the results of UKR for PTCL are unpredictable and therefore that UKR should only be done for medial compartment OA if there is bone on bone. There is a need to develop a method to identify which patients with PTCL will do well so that this subgroup could be treated with UKR.

Knee osteoarthritis affects the distribution of joint moments during gait - Corrected Proof

Joseph A. Zeni, Jill S. Higginson — 2010-06-01

Abstract: Alterations in lower extremity kinetics have been shown to exist in persons with knee osteoarthritis (OA), however few investigations have examined how the intersegmental coordination of the lower extremity kinetic chain varies in the presence of knee joint pathology. The objective of this study was to evaluate how knee OA and walking speed affect total support moment and individual joint contributions to the total support moment. Fifteen healthy subjects and 30 persons with knee OA participated in 3D walking analysis at constrained (1.0m/s), self-selected and fastest tolerable walking speeds. Individual joint contributions to total support moment were analyzed using separate ANOVAs with one repeated measure (walking speed). Linear regression analysis was used to evaluate the relationship between walking speed and joint contribution. Persons with knee OA reduced the contribution of the knee joint when walking at constrained (p=0.04) and self-selected walking speeds (p=0.009). There was a significant increase in the ankle contribution and a significant decrease in the hip contribution when walking speed was increased (p<0.004), however individual walking speeds were not significantly related to joint contributions. This suggests that the relationship between walking speed and joint contribution is dependent on the individual's control strategy and we cannot estimate the joint contribution solely based on walking speed. The slower gait speed observed in persons with knee OA is not responsible for the reduction in knee joint moments, rather this change is likely due to alterations in the neuromuscular strategy of the lower extremity kinetic chain in response to joint pain or muscle weakness.

Knee kinematics during walking at different speeds in people who have undergone total knee replacement - Corrected Proof

Jodie A. McClelland, Kate E. Webster, Julian A. Feller, Hylton B. Menz — 2010-05-31

Abstract: People who have undergone total knee replacement (TKR) experience difficulties in some daily activities including walking. Walking at faster speeds requires more knee flexion and may therefore present a greater challenge following TKR. The aim of this study was to compare the knee kinematics of patients following TKR and unimpaired controls during comfortable and fast walking speeds. Forty patients (22 women, 18 men) 12months following TKR and 40 control participants (matched for age and sex) were assessed during walking at self-selected comfortable and fast speeds using three dimensional motion analysis. The group averages of spatiotemporal and peak kinematic characteristics in the sagittal, coronal and transverse movement planes were compared using univariate analysis of variance with walking speed as a co-variate. The TKR group walked with significantly reduced cadence (p<0.001 at both speeds) and reduced stride length (p<0.001 at both speeds), less knee flexion during stance and swing phases (p<0.001 for both speeds) and less knee extension during stance phase (p<0.024 for comfortable speed; p<0.042 for fast speed). The TKR group also walked with less peak knee external rotation than controls at both speeds (p<0.001 for both speeds). Both groups increased their velocity, cadence and stride length by a similar proportion when walking at fast speed. When walking at a faster speed, spatiotemporal gait parameters and knee motion are altered in a similar manner for both TKR patients and controls. However, at both walking speeds, TKR patients exhibit residual deficits 12months following surgery.

Effects of medial meniscal posterior horn avulsion and repair on meniscal displacement - Corrected Proof

2010-05-31

Abstract: Medial meniscal posterior root avulsion (MMRA) leads to deleterious alteration of medial joint compartment loading profiles and increased risk of medial degenerative changes. Surgical repair restores more normal biomechanics to the knee. Our hypothesis is that MMRA will cause medial meniscal (MM) extrusion and gap formation between the root attachment site and MM. Meniscal root repair will restore the ability of the meniscus to resist extrusion, and reduce gap formation at the defect. Seven fresh frozen human cadaveric knees were dissected and mechanically loaded using a servo-hydraulic load frame (MTS ®) with 0 and 1800N. The knees were tested under three conditions: native, avulsed, and repaired. Four measurements were obtained: meniscal displacement anteriorly, medially, posteriorly, and gap distance between the root attachment site and MM after transection and repair. The medial displacement of the avulsed MM (3.28mm) was significantly greater (p<0.001) than the native knee (1.60mm) and repaired knee (1.46mm). Gap formation is significantly larger in the avulsed compared to repaired state at 0 (p<0.02) and 1800N (p<0.02) and also larger with loading in both avulsed (p<0.05) and repaired (p<0.02) conditions. Therefore, MMRA results in MM extrusion from the joint and gap formation between the MM root and the MM. Subsequent surgical repair reduces meniscal displacement and gap formation at the defect.

Should the ‘no thumb technique’ be the golden standard for evaluating patellar tracking in total knee arthroplasty? - Corrected Proof

Woo-Shin Cho, Jae-Ho Woo, Ho-Youn Park, Yoon-Seok Youm, Byung-Kwan Kim — 2010-05-31

Abstract: We checked intraoperative patellar tracking with both ‘towel clip technique’ and the ‘no thumb technique’ on 97 patients (167 knees) who underwent primary total knee arthroplasty to decide whether to do or not to do lateral retinacular release. Patellar tracking was assessed under pneumatic tourniquet with the no thumb technique first and re-evaluated with the towel clip technique. The tracking was graded as total contact, good contact, lateral contact and subluxation. The knees graded as total or good contact with the no thumb technique were classified into group A; those graded lateral contact or subluxation by the no thumb technique but total or good contact by the towel clip technique were classified into group B; and those graded lateral contact or subluxation by both techniques were classified into group C; in which lateral releases were performed. One hundred three, 53 and 11 knees were classified into groups A, B and C respectively. Of the 167 knees, 64 (38.3%) showed poor tracking (lateral contact or subluxation) with the no thumb technique alone. Re-evaluation of these knees with the towel clip technique significantly reduced the number with poor tracking to 11 (6.6%) knees requiring lateral retinacular release (p<0.05). The patients were followed up for 1year without any patella-related complications occurring. Assessment of the patellar tracking using only the no thumb technique may overestimate the need for lateral retinacular release. The use of the no thumb technique as a screening test, and re-evaluation with the towel clip technique may reduce unnecessary lateral retinacular release.

The histological features of Anteromedial Gonarthrosis — The comparison of two grading systems in a human phenotype of osteoarthritis - Corrected Proof

2010-05-31

Abstract: Anteromedial Gonarthrosis (AMG) displays a well recognised pattern of cartilage damage on the medial tibial plateau. Anteriorly there is a full thickness cartilage defect, with transition to a partial thickness defect, becoming full thickness cartilage in the posterior third of the tibial plateau. The retained posterior cartilage is macroscopically normal. This study characterises the histological changes of AMG and examines the usefulness of two histological assessment tools.Sixteen unicompartmental resection specimens of patients with primary AMG were assessed. Samples were stained with Haematoxylin and Eosin and Safranin-O stains and scored using the modified Mankin grade, and the OOCHAS assessment tool. Each specimen was assessed at five regions along the antero-posterior axis starting from the exposed bone to the region of macroscopically normal cartilage.From anterior to posterior the staining showed a consistent increase in structural integrity and cellularity of the cartilage, matched by a qualitative increase in GAG content. Mean modified Mankin and OOCHAS scores showed a progressive decrease in grade (p<0.001). The OOCHAS grade had a good correlation with the modified Mankin grade (ρ=0.886) and there was good intra- and inter-observer variability with both assessment tools.We conclude that there is progressive decrease in histological score from anterior to posterior in AMG and that the macroscopically normal cartilage seen posteriorly is histologically normal. Both the modified Mankin and OOOCHAS assessment tools are useful in histological grading but we found the OOCHAS easier and quicker to use. We propose that AMG represents a spatial model of progressive cartilage damage.

In vitro biomechanical testing of anterior cruciate ligament reconstruction: Traditional versus physiologically relevant load analysis - Corrected Proof

2010-05-31

Abstract: Various anterior cruciate ligament (ACL) graft-fixation devices exist. In this in vitro study a comparison of biomechanical characteristics of the Cross-Pin and button type fixation devices under practical rehabilitation loads was done. Forty bovine knees and hoof extensor tendons were harvested. After disarticulation, the femoral end of an ACL was prepared with either fixation, using the extensor tendon as graft. The mechanical test was either a single load to failure or load to failure after cycling loads. Twenty specimens were loaded to failure at a rate of 1mm/s, remaining specimens were cycled between 50 and 250N for 1000cycles then failure tested in a similar manner. Results show that both forms of fixation are able to withstand loads that exceed those observed in performing functional activities. Activity-specific stiffness (loads comparable to walking, jogging and stair descent) was lower than linear stiffness for both EndoButton and Cross-Pin, without prior cycling. After cycling, activity-specific stiffness increased to linear stiffness values for the Cross-Pin for all activities. Thus, suggesting that the Cross-Pin provides a more rigid fixation after initial implantation over a wider range of activities, which would theoretically permit a more aggressive rehabilitation protocol and possibly an earlier return to regular activity. In contrast, activity-specific stiffness increased above linear stiffness values for the EndoButton only under heavier loads (jogging and stair descent). Dynamic stiffness was higher and displacement lower for Cross-Pin throughout the cycle test. These results indicate, in ACL reconstruction, that graft complex stiffness should be considered at relevant loads only.

Polyethylene thickness in unicompartmental knee arthroplasty - Corrected Proof

Krishna Lingaraj, Hayden Morris, John Bartlett — 2010-05-31

Abstract: Inadequate polyethylene thickness is a risk factor in the development of polyethylene wear in unicompartmental knee arthroplasty (UKA). The labelled thickness of polyethylene inserts often refers to the combined thickness of the insert and its metal backing. However specific information regarding the actual minimum thickness of the polyethylene is seldom available. We sought to determine the actual minimum thickness of polyethylene inserts used in five contemporary metal-backed UKA designs.The thinnest available insert from each of these designs was identified and measured at the lowest point of its concave articulating surface with a Kincrome electronic digital micrometer. The minimum thickness of the inserts ranged from 3.702mm to 7.859mm (mean values). In two of the inserts, the minimum thickness was found to be less than the recommended minimum thickness of 6mm.Implant manufacturers should clearly indicate the actual minimum thickness of polyethylene inserts on their product labels.

Dual tunnel medial patellofemoral ligament reconstruction for patients with patellar dislocation using a semitendinosus tendon autograft - Corrected Proof

2010-05-31

Abstract: The purpose of this study was to describe a safer and more anatomical technique of MPFL reconstruction and to report the short-term results. The subjects included 20 patients with patellar dislocation with a mean age of 23. The operation was performed using a double-looped autogenous semitendinosus tendon graft. Two small bone tunnels were made at the medial edge of the patella, mimicking the wide patellar insertion of the MPFL and a bone tunnel was made at the femoral insertion site. The free ends of the graft attached to the patella and the loop end was fixed to the femoral side. Five patients were available for follow-up interviews by telephone and the remaining 15 were directly examined by physical examination and radiographic evaluation at 2years or longer postoperatively. The average follow-up period was 30months. Re-dislocation or patellar fracture was not seen in any patients. The average Kujala's score was 96 with a range from 84 to 100. Six patients were classified as excellent and 14 as good, according to the Crosby and Insall grading system. Radiographically, narrowing of the patellofemoral joint space was observed in 2 cases with previous osteochondral fracture out of those who were directly examined. The dual tunnel MPFL reconstruction produces favorable results in subjective and functional assessment of outcome without complications.

Navigated reconstruction of a tibial plateau compression fracture post-virtual reconstruction: A case report - Corrected Proof

2010-05-26

Abstract: Post-traumatic arthrosis is a common problem following tibial plateau fractures. Computed tomography (CT) with 3D reconstruction is essential in facilitating accurate analysis of the fracture type and depth of compression, but is typically only available pre- or postoperatively. Special reconstruction software tools, based on 3D imaging, have been developed. Limiting factors include a lengthy preoperative planning phase. This study assessed a specific type of navigation software, which is currently in use in maxillofacial surgery, to establish whether it might play a critical role in orthopaedic procedures. We report the case of a 43year old female who sustained an isolated tibial plateau compression fracture (Schatzker IIIa), and who was successfully treated with open reduction and internal fixation, with the aid of intraoperative 3D imaging and new software navigation tools. This case demonstrates a combined approach using a new software tool based on intraoperative fluoroscopy-3D imaging.

The relationship between trochlear dysplasia and medial patellofemoral ligament rupture location after patellar dislocation: An MRI evaluation - Corrected Proof

T.S. Weber-Spickschen, J. Spang, L. Kohn, A.B. Imhoff, P.B. Schottle — 2010-05-24

Abstract: The medial patellofemoral ligament (MPFL) and the native trochlear geometry represent two of the most critical components of patellofemoral stability. We sought to define the relationship between trochlear dysplasia and MPFL rupture location in patients with documented patellar dislocations. We hypothesized that patients with lower grades of trochlear dysplasia would have patellar based MPFL ruptures, while patients with higher grade dysplasia would have femoral-sided ruptures.We reviewed post-injury MRIs of 59 patients with documented patella dislocation. Information gathered included: type of trochlear dysplasia in the axial plane MRI, location of MPFL rupture, patellar height ratio, tibial tuberosity to trochlear groove distance (TTTG), number of dislocations prior to MRI, and time between the latest patella dislocation and the MRI.Statistical calculations utilized the Chi-Square-Test.We classified 11 cases as a dysplasia type A, 35 as a type B, 11 as a type C, and 2 cases as a trochlear dysplasia type D. In 7 patients (12%) the MPFL rupture was patella based, in 18 patients (31%) intra-ligamentous, in 33 cases (56%) femoral sided and in one case no MPFL could be identified.In contrast to our original hypothesis, the type of trochlear dysplasia does not appear to be related to the rupture location of the MPFL after patellar dislocation. According to our results, it is not possible to presume the location of the MPFL rupture based on assessment of the trochlear morphology. Therefore, a MRI is mandatory for final indication of any surgery.

Is patellar resurfacing superior than nonresurfacing in total knee arthroplasty? A meta-analysis of randomized trials - Corrected Proof

Ji-Ye He, Lei-Sheng Jiang, Li-Yang Dai — 2010-05-21

Abstract: Conflicting results from abundant studies have made it unclear whether the patella should be resurfaced during total knee replacement. A meta-analysis was undertaken to pool the results of randomized controlled studies (RCTs) and to compare the outcomes and postoperative complications after total knee arthroplasty with patellar resurfacing or nonresurfacing. Sixteen RCTs including 3034 knees between 1966 and December 2009 were analyzed. Reoperation for patellofemoral problems was significantly more likely in the nonresurfacing group (P=0.03). There was no difference between the two groups in terms of anterior knee pain rate, knee pain score, knee society score and knee function score. The results indicate that patellar resurfacing would reduce the risk of reoperation after total knee replacement, but it seems that the benefits are limited on other aspects, and the analysis of high-quality studies shows no advantage of resurfacing over nonresurfacoing group, even in the aspect of reoperation risk. More carefully and scientifically designed RCTs are beneficial and necessary to further prove the results.

Results of total knee replacement with a cruciate-retaining model for severe valgus deformity—A study of 48 patients followed for an average of 9years - Corrected Proof

2010-05-17

Abstract: The objectives of the present study were to find out the results and the factors affecting survival after primary knee arthroplasty with a cruciate-retaining prosthesis in severe valgus deformity. Forty-eight patients (52 knees) participated in the current follow-up study. All patients were followed at least 5years or to first revision. Mean follow-up time was 9years (range, 1 to 17years).The Kaplan–Meier analysis revealed 79% (95% CI 68% to 91%) survival rate with revision for any reason and 81% (95% CI 70% to 93%) survival rate with revision for instability as an endpoint at 10years. Preoperatively TFA was 23° (range, 15°–51°) in valgus and 7° (range, 21° valgus–4° varus) in valgus postoperatively. Of the 14 re-operated patients, eight were revised because of progressive postoperative medial collateral ligament instability. All re-operations were performed during the first 4years of the follow-up. The mean TFA was 15.5° valgus postoperatively for those eight and the odds ratio for a revision was 2 (95% CI 1–3, p=0.025) when compared to the rest of the study population. The residual valgus deformity increases the risk of re-operation and it should be avoided. If proper soft-tissue balance cannot be achieved or there is no functional medial collateral ligament present more constrained implants should be used. In selected cases where both bony correction and ligament balancing have properly been achieved the use of a cruciate-retaining type of prosthesis is justified.