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Lucas C. Bianco, James M. May, Smokey L. Fermin, Robert Oates and Scott W. Cheatham

Key Points ▸ Patella tendinopathy, or jumper’s knee, is common in basketball players. ▸ Treatment programs utilizing positional release therapy may be effective for patients diagnosed with patella tendinopathy. ▸ Positional release therapy paired with thigh and hip therapeutic exercise improved

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Tzu-Chieh Liao, Joyce H. Keyak and Christopher M. Powers

example, the model used to estimate patellofemoral joint stress was generic and did not account for subject-specific variations in patellofemoral joint geometry and/or patella alignment. This is important, as previous studies have reported that persons with PFP may have abnormal joint structure (ie, patella

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Kathryn E. Keenan, Saikat Pal, Derek P. Lindsey, Thor F. Besier and Gary S. Beaupre

Cartilage material properties provide important insights into joint health, and cartilage material models are used in whole-joint finite element models. Although the biphasic model representing experimental creep indentation tests is commonly used to characterize cartilage, cartilage short-term response to loading is generally not characterized using the biphasic model. The purpose of this study was to determine the short-term and equilibrium material properties of human patella cartilage using a viscoelastic model representation of creep indentation tests. We performed 24 experimental creep indentation tests from 14 human patellar specimens ranging in age from 20 to 90 years (median age 61 years). We used a finite element model to reproduce the experimental tests and determined cartilage material properties from viscoelastic and biphasic representations of cartilage. The viscoelastic model consistently provided excellent representation of the short-term and equilibrium creep displacements. We determined initial elastic modulus, equilibrium elastic modulus, and equilibrium Poisson’s ratio using the viscoelastic model. The viscoelastic model can represent the short-term and equilibrium response of cartilage and may easily be implemented in whole-joint finite element models.

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Matthew J. Morrison, Cheryl A. Coker, Michael S. McGuire and Angela M. Mickle

Column-editor : Joseph J. Piccininni

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Jennifer M. Plos, Renee L. Polubinsky and Joe McKown

Edited by Joseph J. Piccininni

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Ben A. Bloomer and Chris J. Durall

Clinical Scenario:

Patellofemoral pain syndrome (PFPS) is one of the most common disorders affecting the lower extremities. To improve function and decrease pain, affected individuals often undergo a guided rehabilitation program. Traditional programs have concentrated on quadriceps strengthening and other knee-focused exercises, but recent literature suggests that adding hip-muscle strengthening may improve outcomes. This review was conducted to determine the extent to which current evidence supports the addition of hip-muscle strengthening to a knee-focused strengthening and stretching program in the treatment of PFPS.

Focused Clinical Question:

Does the addition of hip-muscle strengthening to a knee-focused strengthening and stretching program improve outcomes in patients with PFPS?

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Susanne Fuchs, Guido Schuette, Hartmut Witte, and Carsten Oliver Tibesku

A new design of total knee prosthesis without anterior patellar flange was developed to preserve the anatomical shape of the patellofemoral joint. The aim of the current study was to experimentally compare patellofemoral contact area and pressure in a nonreplaced knee, in a knee after implantation of a conventionally designed total knee arthroplasty, and in a knee after implantation of the newly designed total knee arthroplasty without patellar flange. Six cadaveric legs were examined before and after implantation of either a conventional or a newly developed total knee arthroplasty, both without patellar replacement. The essential change in design is the absence of an anterior patellar flange. Contact area and pressure were measured using pressure sensitive films in 45°, 60°, 90°, and 120° of flexion and the results were compared between the different prosthesis designs and with the nonreplaced knee. The prosthesis without patellar flange showed less average and maximum pressure than the conventional prosthesis. Compared with the nonreplaced knee, the conventional prosthesis led to increased average and maximum pressure and decreased contact area. In an experimental test setup, the newly developed total knee arthroplasty without patellar flange showed reduced patello-femoral contact pressure in comparison with a total knee prosthesis with conventional patellofemoral design. This could possibly lead to a lower incidence of anterior knee complaints in patients.

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John D. Willson and Irene S. Davis

Context:

Lower extremity (LE) weakness might be associated with altered mechanics during weight bearing in subjects with patellofemoral pain syndrome (PFPS).

Objective:

To analyze LE strength, mechanics, and the association between these variables among women with and without PFPS during a simulated athletic task.

Design:

Case control.

Setting:

Motion-analysis laboratory.

Subjects:

20 women with PFPS and 20 healthy women.

Main Outcome Measures:

Peak isometric lateral trunk-flexion, hip-abduction, hip external-rotation, knee-flexion, and knee-extension strength, as well as hip- and knee-joint excursions and angular impulses during single-leg jumps.

Results:

PFPS subjects produced less hip-abduction, hip external-rotation, and trunk lateral-flexion force than the control group. The PFPS group also demonstrated greater hip-adduction excursion and hip-abduction impulses. The association between the strength measurements and LE mechanics was low.

Conclusions:

Women with PFPS demonstrate specific weaknesses and altered LE mechanics. Weakness is not, however, highly correlated with observed differences in mechanics.

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Pablo Fanlo-Mazas, Elena Bueno-Gracia, Alazne Ruiz de Escudero-Zapico, José Miguel Tricás-Moreno and María Orosia Lucha-López

lack of flexibility of several muscles of the thigh has been documented as a possible factor contributing to PFP, 4 – 6 and it is a common finding in patients with PFPS. 7 – 9 A tight iliotibial band (ITB) can lead to laterally located patella and an abnormal patellar tracking pattern. 4 , 6 This

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Laura C. Slane, Stijn Bogaerts, Darryl G. Thelen and Lennart Scheys

either the proximal or distal tendon, with the corresponding anatomical landmark (notch of the tibial tuberosity or the distal edge of the patella, respectively; Figure  1 ) in view. Five repeat trials from each transducer position were collected for each subject. Table 1 Summary of Test Protocol Trial