[Comparison of short-median term outcome between total knee arthroplasty and unicondylar arthroplasty in patients with osteoarthritis affected with medial compartment mainly of the knee].

OBJECTIVE: To explore the short and mid-term outcome and surgical technique of minimally invasive unicondylar knee arthroplasty (UKA) for osteoarthritis affected with medial compartment predominantly of the knee. METHODS: From January 2003 to April 2009, all operations were performed by a senior surgeon. All patients followed the following criteria: (1) More than 50 years old and symptoms concentrated on the medial side of knee; (2) Osteoarthritis characterized mainly by medial compartment on X-rays and staged I-III by Ahlback staging system. There was no symptom of patellofemoral joint. Varus deformity was less than 15 degrees and flexuous deformity less than 10 degrees; (3) Knee joint was stable with intact main ligaments. METHODS: Forty-eight patients (48 knees) with osteoarthritis of the knee undergone UKA by minimally invasive surgery. The patients included 9 males and 39 females with an age range of 52 - 71 years old and a body mass index of 21.1 - 32.7. And 52 matched patients included 9 males and 39 females aged from 53 to 76 years old and with a body mass index of 21 - 32.4 undergone TKA. The pain and range of motion (ROM) of knees were evaluated by HSS score system before and after UKA and TKA. RESULTS: All patients were followed up for an average of 52.4 months (range: 12 - 82). In UKA group, all patients received pain relief and there was no continuous anterior knee pain. The range of motion of knee reached a median of 126 degrees and obtained a postoperative HSS score of 96 versus a preoperative score of 62. The rate of excellent and good outcome approached 97%. The results were similar in TKA group. However, in UKA group, the patients had a lesser blood loss, a faster recovery and a lower cost than those in TKA group. CONCLUSION: The short and mid-term outcome of UKA for osteoarthritis of knee affected with medial compartment is satisfactory. UKA is minimally invasive and has a faster recovery. Mild asymptomatic degeneration of patellofemoral joint and over-weight (BMI < 32) do not affect the short and mid-term outcome.