Short-Term Clinical Outcomes of a Manual "Inside-Out" Algorithm for Correcting Ranawat Grade II and III Valgus Deformity in Total Knee Arthroplasty.

Abstract

Background: Total knee arthroplasty (TKA) in the fixed valgus knee is technically demanding due to lateral soft-tissue contractures and the risk of peroneal nerve injury. This study evaluates the clinical and radiographic outcomes of a manual "inside-out" soft-tissue balancing algorithm for Ranawat Grade II and III valgus deformities.

Materials and methods: We prospectively evaluated 30 knees (24 patients) with advanced arthritis and valgus deformity (> 10°) treated between 2016 and 2019. Surgical correction followed a sequential "inside-out" protocol: posterior cruciate ligament (PCL) resection, posterolateral capsule (PLC) release, and selective iliotibial band (ITB) pie-crusting within a strict 1-cm safety zone. Clinical outcomes were measured using the Knee Society Score (KSS). Radiographic analysis focused on the tibiofemoral angle and component alignment. Results were compared with traditional manual techniques and novel robotic-assisted data.

Results: The mean KSS improved significantly from 19.63 preoperatively to 87.17 at the final follow-up (p < 0.001). The mean tibiofemoral valgus angle was corrected from 24.28° to 4.97°. Absolute medial stability was achieved in 96.6% of cases. Notably, in our series, no cases of peroneal nerve palsy were observed (0%; 95% CI: 0.0%-11.6%), suggesting a high safety profile for the inside-out technique. Two intraoperative periprosthetic fractures (6.6%) occurred and were managed successfully.

Discussion: Our manual algorithm achieved safety and alignment outcomes comparable to novel robotic-assisted TKA series. The "inside-out" approach provides excellent exposure and controlled lengthening of contracted structures while protecting neurovascular anatomy.

Conclusion: The manual "inside-out" technique is a safe, reproducible, and cost-effective method for correcting severe valgus deformity. It provides high precision in gap balancing and effectively eliminates the risk of peroneal nerve palsy in Ranawat Grade II and III cases. It ensures high precision in gap balancing and effectively minimizes the risk of peroneal nerve palsy, providing a reliable alternative in settings where robotic technology is inaccessible.