Lateral subvastus approach to total knee arthroplasty: A novel surgical technique and retrospective review of 931 consecutive cases

Background: The lateral muscle-sparing approach total knee arthroplasty (TKA) has been detailed and indicated selectively for severe valgus deformities. We present the largest, to date, consecutive series of lateral subvastus TKAs and we hypothesize that preoperative alignments would demonstrate no differences in range of motion (ROM), knee society scores (KSS), kneeling ability, patient satisfaction, or complications. Materials and methods: This retrospective study examined 931 primary TKAs in 824 patients performed through the lateral subvastus approach with one to two years follow-up. All primary TKAs performed between July 2020 and February 2022 were included. We used descriptive statistics, chi-squares, and analysis of variance (ANOVA) to examine the cohort. Significance was set to p < .05. Results: Patient's ROM significantly improved by six weeks, (1-117, P < .05) with continued improvement by one-year, (0-121, P < .05) with no significant dif-ferences in alignment in extension, (P = .142) or flexion, (P = .253). There were also no significant differences in alignment in KSS scores at six-weeks, (P = .635), three-months, (P = .829), six-months, (P = .836), one-year, (P = .641) or two-years, (P = .776). There were no significant differences in kneeling ability, (P = .563), and 85% of patients reported being able to kneel. There were no differences in patient satisfaction, (P=.436), and 90% of patients reported being satisfied. There was a low 8% complication rate in this cohort. Neutral and varus knees were less likely than valgus knees to develop deep vein thrombosis (DVT; P < .05) or have a medial collateral ligament (MCL) injury (P < .05). Conclusions: Patients with varus, valgus, and neutral knees had similar outcomes when using a lateral subvastus approach to TKA in ROM and KSS that were stable over two years with similar kneeling ability and satisfaction. There was a low incidence of complications with neutral and varus knees at the lowest risk. A lateral subvastus approach to TKA can be safe and effective for all knee deformities.