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Nicholas H. Yang, Paul K. Canavan and Hamid Nayeb-Hashemi

Subject-specific models were developed and finite element analysis was performed to observe the effect of the frontal plane tibiofemoral angle on the normal stress, Tresca shear stress and normal strain at the surface of the knee cartilage. Finite element models were created for three subjects with different tibiofemoral angle and physiological loading conditions were defined from motion analysis and muscle force mathematical models to simulate static single-leg stance. The results showed that the greatest magnitude of the normal stress, Tresca shear stress and normal strain at the medial compartment was for the varus aligned individual. Considering the lateral knee compartment, the individual with valgus alignment had the largest stress and strain at the cartilage. The present investigation is the first known attempt to analyze the effects of tibiofemoral alignment during single-leg support on the contact variables of the cartilage at the knee joint. The method could be potentially used to help identify individuals most susceptible to osteoarthritis and to prescribe preventive measures.

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Philip Bright and Karen Hambly

Context:

Autologous chondrocyte implantation (ACI) is a tissue-engineered surgical technique initially developed for articular cartilage repair of isolated chondral lesions of the knee. Third-generation techniques (ACI3) are now available that deliver autologous cultured chondrocytes into the defect using cell scaffolds. The successful outcomes of these techniques have some dependency on presurgical and postsurgical patient rehabilitation.

Objectives:

To determine if the standard of reporting for rehabilitation has improved in ACI3 studies; previous reviews in this field recommended describing the detail of this rehabilitation and patient compliance as integral elements.

Evidence Acquisition:

A computerized search was performed in March 2013. Criteria for inclusion were any studies that evaluated or described the process of ACI3 in the knee and subsequent rehabilitation. The modified Coleman Methodology Score (CMS) was used to rate the standard of reporting of rehabilitation and surgical procedures; review articles were also evaluated for quality using the Strength of Recommendation Taxonomy (SORT). Mean scores, odds ratios, 95% confidence intervals, and Mann-Whitney U statistics were calculated.

Evidence Synthesis:

An improvement in mean CMS was seen compared with previous reviews, but rehabilitation reporting scores were lower than their surgical equivalent; significant association was seen between studies with rehabilitator involvement and high scores in the individual CMS rehabilitation element. Predominant SORT scores of 2A indicated medium strength of recommendation.

Conclusions:

The CMS provides a general overview of methodological quality, but a more specialized tool to report on the quantitative and qualitative aspects of the rehabilitation process would help raise the standards. It is recommended that rehabilitation therapists be included as key members of research teams and be involved in the design, implementation, and reporting of future studies.

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Daniël M. van Leeuwen, Fabian van de Bunt, Cornelis J. de Ruiter, Natasja M. van Schoor, Dorly J.H. Deeg and Kaj S. Emanuel

present, a sensitive performance battery can detect a clinically meaningful difference in functional performance related to knee OA. For functioning without cartilage, older people with radiographic knee OA who self-report no functional limitations do score lower on a performance battery. Acknowledgments

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Melinda Terry

Edited by A. Louise Fincher

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Jennifer S. Howard, Jay R. Ebert and Karen Hambly

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Brian L. Parker

Column-editor : G. Monique Butcher Mokha

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Jennifer S. Howard, Carl G. Mattacola, David R. Mullineaux, Robert A. English and Christian Lattermann

Context:

It is well established that autologous chondrocyte implantation (ACI) can require extended recovery postoperatively; however, little information exists to provide clinicians and patients with a timeline for anticipated function during the first year after ACI.

Objective:

To document the recovery of functional performance of activities of daily living after ACI.

Patients:

ACI patients (n = 48, 29 male; 35.1 ± 8.0 y).

Intervention:

All patients completed functional tests (weight-bearing squat, walk-across, sit-to-stand, step-up/over, and forward lunge) using the NeuroCom long force plate (Clackamas, OR) and completed patient-reported outcome measures (International Knee Documentation Committee Subjective Knee Evaluation Form, Lysholm, Western Ontario and McMaster Osteoarthritis Index [WOMAC], and 36-Item Short-Form Health Survey) preoperatively and 3, 6, and 12 mo postoperatively.

Main Outcome Measures:

A covariance pattern model was used to compare performance and self-reported outcome across time and provide a timeline for functional recovery after ACI.

Results:

Participants demonstrated significant improvement in walk-across stride length from baseline (42.0% ± 8.9% height) at 6 (46.8% ± 8.1%) and 12 mo (46.6% ± 7.6%). Weight bearing on the involved limb during squatting at 30°, 60°, and 90° was significantly less at 3 mo than presurgery. Step-up/over time was significantly slower at 3 mo (1.67 ± 0.69 s) than at baseline (1.49 ± 0.33 s), 6 mo (1.51 ± 0.36 s), and 12 mo (1.40 ± 0.26 s). Step-up/over lift-up index was increased from baseline (41.0% ± 11.3% body weight [BW]) at 3 (45.0% ± 11.7% BW), 6 (47.0% ± 11.3% BW), and 12 mo (47.3% ± 11.6% BW). Forward-lunge time was decreased at 3 mo (1.51 ± 0.44 s) compared with baseline (1.39 ± 0.43 s), 6 mo (1.32 ± 0.05 s), and 12 mo (1.27 ± 0.06). Similarly, forward-lunge impact force was decreased at 3 mo (22.2% ± 1.4% BW) compared with baseline (25.4% ± 1.5% BW). The WOMAC demonstrated significant improvements at 3 mo. All patient-reported outcomes were improved from baseline at 6 and 12 mo postsurgery.

Conclusions:

Patients' perceptions of improvements may outpace physical changes in function. Decreased function for at least the first 3 mo after ACI should be anticipated, and improvement in performance of tasks requiring weight-bearing knee flexion, such as squatting, going down stairs, or lunging, may not occur for a year or more after surgery.

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Simon M. Thompson, Mary Jones, Jonathon R. Lavelle and Andy Williams

The etiology of osteochondritis dissecans is hypothesized as repetitive microtrauma, resulting in an interruption of blood supply. Due to the location of the most common lesions on the medial femoral condyle, impingement of either the medial tibial spine or inferior pole of the patella against the adjacent medial femur may be responsible. It is much more common in athletic males than other groups. This article reviews the current treatment options for lesions around the knee.

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Zeike A. Taylor and Karol Miller

An important and longstanding field of research in orthopedic biomechanics is the elucidation and mathematical modeling of the mechanical response of cartilaginous tissues. Traditional approaches have treated such tissues as continua and have described their mechanical response in terms of macroscopic models borrowed from solid mechanics. The most important of such models are the biphasic and single-phase viscoelastic models, and the many variations thereof. These models have reached a high level of maturity and have been successful in describing a wide range of phenomena. An alternative approach that has received considerable recent interest, both in orthopedic biomechanics and in other fields, is the description of mechanical response based on consideration of a tissue's structure—so-called microstructural modeling. Examples of microstructurally based approaches include fibril-reinforced biphasic models and homogenization approaches. A review of both macroscopic and microstructural constitutive models is given in the present work.

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Timothy C. Wilson and Darren L. Johnson