Quadriceps recovery after subvastus total knee arthroplasty in valgus deformity: a systematic review and pooled descriptive analysis

Abstract

The subvastus approach preserves the extensor mechanism, but its efficacy in total knee arthroplasty (TKA) for valgus deformity remains unclear. This systematic review synthesizes available evidence on quadriceps recovery and clinical outcomes after subvastus TKA specifically in patients with valgus deformity. A systematic search of PubMed, Cochrane Library, and Embase (2000–2025) was performed. Studies reporting outcomes of the subvastus approach in valgus TKA were included. The primary outcome was time to straight leg raise (SLR). Secondary outcomes included functional scores, range of motion (ROM), pain (VAS), and complications. Due to single-arm designs and high heterogeneity, a formal meta-analysis was not appropriate; results are presented descriptively with pooled means for illustrative purposes only. Three retrospective studies (286 valgus knees) were included. Time to SLR ranged from 0.92 to 2.0 days across studies (pooled descriptive mean: 1.35 days; I2 = 99%). Functional scores improved substantially (e.g., American Knee Society Score: 39 to 91; Hospital for Special Surgery Score: 35 to 93). Postoperative ROM gains ranged from 9° to 27° across studies, with final flexion exceeding 109° in all cohorts. Postoperative rest pain scores ranged from 2.3 to 4.6; walking pain was reported as 5.2 in one study. Complication rates were low, with two revisions (0.7%) and one transient nerve palsy (0.3%) among 286 knees. No approach-related major complications were reported. The subvastus approach appears viable for selected valgus knees, associated with rapid quadriceps recovery, functional improvement, and low complications within the available evidence. However, these findings derive from only three retrospective, single-arm studies with substantial heterogeneity. High-quality prospective comparative studies are required.