The role of the popliteus tendon in total knee arthroplasty: a cadaveric study: SIGASCOT Best Paper Award Finalist 2014

this study was conducted to investigate the influence of the popliteus tendon (PT) on the static stability of total knee arthroplasty (TKA). METHODS: twenty knees were used. In 10 right knees, a cruciate-retaining (CR) TKA trial prosthesis was implanted; in the other ten knees (left knees), the posterior cruciate ligament was cut and a posterior substitution (PS) TKA trial prosthesis was implanted. Lamina spreaders were set at 100 N of tension, one on the medial and one on the lateral articular space. Gaps were then measured with a caliper before and after PT sectioning. RESULTS: the correlation between femoral dimensions and popliteus insertion distance from articular surfaces was measured with the Pearson correlation index and considered significant. In the CR-TKA group, medial and lateral gap measurements showed a significant increase after PT sectioning both in flexion and in extension. In the PS-TKA group, lateral gap measurements showed a significant increase after PT sectioning both in flexion and in extension, while the medial gap measurements increased significantly only in flexion. CONCLUSIONS: PT sectioning destabilized both the lateral and the medial aspects of the knee. A greater effect was observed in the lateral compartment. The most statistically reliable effect was observed with the knee in flexion. In addition, we observed that preserving the PCL does not prevent lateral gap opening after PT sectioning. CLINICAL RELEVANCE: PT should always be preserved when performing a TKA, because its resection can affect gap balancing, in flexion and in extension. TYPE OF STUDY: controlled laboratory study.