Does the Kinematch® Prosthesis Impair Knee Flexion in Patients with Trochlear Dysplasia?
Background: Patellofemoral replacements are used to treat isolated patellofemoral arthritis in carefully selected patients. The Kinematch® custom-designed implant is placed directly on subchondral bone, leading critics of the device to believe that this results in overstuffing and limitation of flexion in cases of trochlear dysplasia; the current study aims to evaluate this premise.
Methods: A retrospective analysis of a consecutive series of 24 patients (32 knees) was conducted. Trochlear dysplasia was evaluated using pre-operative axial CT scans, and knees were categorized as having minimal or moderate/severe dysplasia (moderate = flat trochlea, severe = convex trochlea). The primary outcome was post-operative knee flexion.
Results: There was no statistical or clinical difference in post-operative knee flexion between the minimal (120°+12) and the moderate/severe dysplasia (117°+9) groups (p=.34).
Conclusions: Use of the Kinematch® patient-specific custom trochlear component does not significantly limit flexion in cases of trochlear dysplasia, and although the surgeon has the ability to deepen the trochlea by way of the pre-operative model, this is not necessary.
Keywords: Patellofemoral replacement; custom; flexion; trochlear dysplasia
Level of Evidence: III, Case-control study
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Copyright (c) 2014 Ronald Grelsamer, MD, Paul Cavallaro, BS
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