objectives: The management of severe varus deformities in patients undergoing total knee arthroplasty (TKA) often involves the sequential release of all medial knee stabilizing structures. Herein, we introduce a new release algorithm that maintains the integrity of one of the main knee structures (semimembranosus and posteromedial) during the procedure. This new approach is compared with soft tissue release (STR) methods and the differences between the methods are analysed in terms of prosthesis type, functional outcomes, and postoperative complications.

Methods: A total of 174 TKA patients with a varus deformity of over 15º took part in this study. Two different surgical approaches for soft tissue release (STR) approaches were employed: the classic method involving four stages (1: deep medial collateral ligament (MCL), joint capsule, and proximal tibial osteophyte release; 2: semimembranosus and posteromedial release; 3: superficial MCL release; stage 4: pes anserine release) compared to a new method using pie-crusting the superficial MCL. Additionally, the knee function was assessed based on the knee society score (KSS) and the Oxford knee score (OKS).

Results: Two groups were neither different in their baseline characteristics nor in postoperative functional KSS and OKS. However, the classic STR group underwent constrained prostheses implantation and encountered two cases of postoperative instability, while all the patients in the new method group remained stable.

Conclusion: Despite several important limitations of this study, it seems that omitting the semimembranosus and posteromedial release and using pie-crusting of the MCL after Stage 1 of STR reduces the risk of medial joint instability and the need for implanting a more constrained prosthesis. However, this statement must be confirmed by randomized controlled trials.