Total Knee Arthroplasty for Secondary Osteoarthritis in Patients With Multiple Hereditary Exostoses: A Case Series.

BACKGROUND Multiple hereditary exostoses (MHE) is a rare genetic disorder characterized by multiple osteochondromas, often leading to joint deformity and early-onset osteoarthritis (OA). The knee is one of the most commonly affected joints, and progressive deformity and malalignment may eventually require surgical intervention. Total knee arthroplasty (TKA) in patients with MHE remains technically demanding because of distorted joint anatomy and soft tissue imbalance. Because of the rarity of this condition, published reports describing surgical strategies and clinical and radiographic outcomes of TKA in patients with MHE remain limited. CASE REPORT We report 4 cases of MHE treated with TKA for advanced OA. Preoperative evaluation demonstrated varus or valgus deformities and limited range of motion in all cases. In all cases, TKA was performed using the measured resection technique. Two cases required constrained prostheses due to soft tissue imbalance. In 1 patient with a history of femoral fracture fixation and an obstructed femoral canal, portable navigation was employed to facilitate accurate bone resection. All patients achieved pain relief, with improved hip-knee-ankle (HKA) angle and range of motion. The mean 2011 Knee Society objective score improved from 48 preoperatively to 94.5 at the final follow-up, and the mean 2011 Knee Society functional score improved from 36 to 54.5. CONCLUSIONS Our experience suggests that TKA can yield favorable short-term clinical and radiographic outcomes in patients with MHE. Despite the technical challenges associated with distorted anatomy and soft tissue imbalance, individualized preoperative planning and appropriate intraoperative decision-making - including the selective use of constrained implants and navigation systems - can contribute to successful surgical outcomes.