Patellar tendon buckling in post-operative total knee arthroplasty patients is more prominent than in healthy controls.

Recent evidence suggests the patellar tendon undergoes buckling during normal knee flexion, which likely contributes to the functioning of the extensor mechanism. Thus, evaluating buckling in patients following total knee arthroplasty (TKA), where extensor mechanism dysfunction remains a common complication, may be relevant. The study goals were to identify whether post-TKA patients exhibit differences in patellar tendon buckling from healthy, similarly-aged adults and whether such buckling correlates with knee and patellar tendon health. Patellar tendon buckling was assessed during passive knee flexion using ultrasound in post-TKA patients (n = 20; 12M, 68 ± 8 years) and compared with previously reported data from healthy adults (n = 12; 12M; 70 ± 8 years). Patients exhibited significantly larger (p < 0.01) buckling magnitude and angles than healthy adults, and reduced distal buckling was linked with better Knee Society Scores (p = 0.04, R2 = 0.24). The greater patellar tendon buckling observed in post-TKA patients could arise due to factors related to the surgery itself (e.g. infrapatellar fat pad resection) or it may be that post-TKA patients had greater patellar tendon buckling before their procedure. Alterations in patellar tendon buckling may predispose individuals to post-surgical complications including instability, anterior knee pain, and extensor mechanism dysfunction, with further work necessary to elucidate potential links.