Lateral unicompartmental knee arthroplasty retaining partial internal fixation for traumatic osteoarthritis: a case report

Background Post-traumatic osteoarthritis (PTOA) following tibial plateau fractures presents a clinical challenge, particularly in younger patients with high functional demands. This article aims to present the results of lateral unicompartmental knee arthroplasty (LUKA) retaining partial internal fixation in PTOA. Case presentation A 55-year-old female patient developed PTOA of the lateral compartment one year following operation for a tibial plateau fracture. The patient reported a one-year history of knee pain and experienced walking difficulties in the past eight weeks. The patient underwent LUKA under spinal anesthesia combined with nerve block. Strategically, instead of complete removal of the existing hardware, three critical screws beneath the tibial plateau were shortened and re-tightened to provide structural reinforcement while avoiding interference with prosthetic implantation. The patient was able to ambulate independently shortly after surgery. At the 3-month follow-up, knee function was satisfactory, with the Knee Society Score improving from 62 to 92. At the 6-month follow-up, no significant persistent pain or major complications such as prosthetic loosening, fracture, or wear. Conclusion This case demonstrates that LUKA with retention of partial internal fixation may represent a feasible strategy in carefully selected patients with PTOA and osteoporosis. This innovative approach preserves critical structural support, minimizes iatrogenic bone loss, and is associated with encouraging short-term clinical outcomes, offering a novel perspective for managing complex post-traumatic knees. However, long-term follow-up is necessary to verify these results.