Gap changes after popliteus-tendon resection in PS-TKA: A cadaveric study in Thai female knees

Popliteus-tendon injury during total knee arthroplasty (TKA) may result in imbalanced soft-tissue tension; however, it is unclear whether complete popliteus-tendon resection is a factor which contributes to knee instability following TKA. We performed an isolated complete resection of the popliteus tendon during a standard posterior stabilised TKA (PS-TKA) in 14 normal knees of Thai female cadavers and measured gap differences in both knee flexion and extension. In addition, we measured the distance from the femoral attachment of the popliteus tendon to the femoral condyles including the distance from the most distal femoral attachment of the popliteus tendon to the distal lateral femoral condyle (DFa-DLFC), and the distance from the most posterior femoral attachment of the popliteus tendon to the posterior lateral femoral condyle (PFa-PLFC). After completion of bone cuts, static flexion and extension gaps were measured with a tension of 98 N under intact and complete tendon resection, respectively. The mean DFa-DLFC and PFa-PLFC distances were 8.9 mm (range, 6.4–10.5 mm) and 11.5 mm (range, 9.5–14.0 mm), respectively. Of 14 cadaveric knees, 35.7% had a DFa-DLFC distance < 9 mm. Flexion and extension gaps significantly increased in both medial and lateral sides after complete popliteus resection with a similar mean increased value of 1.85 mm. The clinical evaluation of gap changes after popliteus resection on knee stability should be further investigated. A routine 9-mm distal femoral bone cut may injure the popliteus tendon during TKA conducted on small knees.