[Early efficacy of lateral unicondylar replacement for lateral compartment osteoarthritis of the knee]

Objective: To discuss the surgical technique of lateral unicondylar knee replacement (UKR) for patients with lateral compartment osteoarthritis and evaluate its recent clinical efficacy. Methods: A retrospective analysis was conducted on 22 cases of lateral compartment osteoarthritis patients receiving lateral UKR at Orthopedic Department, Beijing Chao Yang Hospital, Capital Medical University from January 2016 to January 2019.There were 8 males (8 knees) and 14 females (14 knees), aged 65.7 years(range: 54 to 83 years). All patients completed preoperative imaging examination and excluded extra-articular deformity. Lateral parapelatellar approach was used for the operation and the tibial osteotomy was performed by extramedullary positioning.The residual cartilage of the external condyle was removed by pendulum saw to subchondral bone.Appropriate prosthesis were selected, and the tightness of the gap and the stability of the joints were repeatedly confirmed during the operation. The postoperative complications and the results of physical and imaging examinations were collected. The preoperative and postoperative Oxford knee Score (OKS) and knee society score (KSS) of patients were recorded and compared by paired t test. Results: All patients were followed up for 24.6 months (range: 8 to 40 months). No complications such as incision exudation, skin necrosis and deep venous thrombosis of lower limbs were found after the operation.No cases of prosthesis loosening, excessive wear of pads, dislocation and postoperative infection were found at the last follow-up.The OKS decreased from 46.5±3.1 preoperative to 22.4±3.3 postoperative(t=13.4, P=0.00) and KSS improved from 69.5±8.7 preoperative to 90.2±7.4 postoperative (t=16.9, P=0.00). Conclusions: For the treatment of lateral compartment osteoarthritis, UKR has the advantages of rapid recovery of knee function, less complications and less trauma.The short-term efficacy is satisfactory, but the long-term efficacy remains to be observed.