Intraoperative patellar maltracking and postoperative radiographic patellar malalignment were more frequent in cases of complete medial collateral ligament release in cruciate-retaining total knee arthroplasty

BackgroundPatellar maltracking after total knee arthroplasty (TKA) can lead to significant patellofemoral complications such as anterior knee pain, increased component wear, and a higher risk of component loosening, patellar fracture, and instability. This study was to investigate the preoperative and operative variables that significantly affect patellar tracking after cruciate-retaining TKA.MethodsWe studied 142 knee joints in patients who had undergone TKA: the knees were dichotomized based on postoperative patellar tracking, which was evaluated on patellar skyline, axial-projection radiographs: group 1, normal patellar tracking (lateral tilt <= 10 degrees and displacement <= 3mm) and group 2, patellar maltracking (lateral tilt >10 degrees or displacement >3mm). The patients' demographic data and clinical and radiographic measurements obtained before and after surgery were compared between the two groups.ResultsPreoperative lateral patellar displacement was greater (4.12.6mm vs. 6.03.5mm), as was the frequency of medial collateral ligament (MCL) release (3/67 vs. 24/75) in group 2 than in group 1 (p<0.001 and p<0.001, respectively). The distal femur was cut in a greater degree of valgus in group 1 than in group 2. (6.3 +/- 0.8 degrees vs. 6.0 +/- 0.8 degrees) (p=0.034).Conclusions Complete release of the MCL during surgery was associated with patellar maltracking (logistic regression: p=0.005, odds ratio=20.592). Surgeons should attend to patellar tracking during surgery in medially tight knees.Level of evidence Retrospective comparative study, level III.