Lateral approach total knee arthroplasty achieves equivalent patellar tracking in severe valgus deformity compared to mild valgus deformity

Abstract

Purpose Patellar tracking problems represent 2-10% of complications of total knee arthroplasties (TKA) in valgus knees. However, there are no studies assessing patellar tracking according to the severity of the valgus deformity. The hypothesis was that lateral approach TKA in severe valgus deformity provides equivalent patellar tracking to that in knees with mild valgus deformity. Methods Between 1988 and 2016, 77 TKAs were performed via a lateral approach on a severe valgus deformity (HKA > 195°). Forty-three TKAs performed without tibial tubercle osteotomy and with complete radiological data were included in this study. These were compared with 86 matched TKAs performed via a lateral approach with a mild valgus deformity (HKA between 181° and 190°). Patellar tilt and patellar position were assessed by axial view radiographs at the last follow-up. Complications and clinical outcomes were also evaluated. ResultsThe follow-up was mean 52 ± 21 months in the severe valgus group. No signiicant diferences were found between the severe valgus deformity group and the mild valgus deformity groups in patellar tilt (1.6° ± 6.6° versus 1.9° ± 3.2°, respectively) or patellar subluxation. There were complications in 12% (n = 5) and 11% (n = 9) of the severe valgus group and the mild valgus group respectively, without signiicant diference. There was no signiicant diference in extensor mechanism complication rate (2.3% versus 4.7%, respectively). Conclusion Lateral parapatellar approach, without tibial tubercle osteotomy, for TKA in severe valgus deformity results in good patellar tracking. With this approach, the extensor mechanism complication rate in severe valgus deformity was not higher than for mild valgus deformity. Level of evidence III. KeywordsTotal knee arthroplasty • Severe valgus deformity • Lateral approach • Patellar tilt Abbreviations BMI Body mass index FMA Femoral mechanical angle HKA Hip knee ankle KSS Knee Society Score OA Osteoarthritis * Cécile Batailler