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.
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.
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.
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.
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.