Hybrid total knee arthroplasty: a 3- to 6-year outcome analysis

We retrospectively analyzed the outcomes of hybrid total knee arthroplasty (TKA) with Miller Galante I (MG I) prostheses in 113 consecutive patients (140 knees). The mean follow-up period was 4.8 years (range 3.2-6.6). There were 135 cases of osteoarthritis and five of rheumatoid arthritis. The average age of patients at the time of surgery was 62.6 years. The Hospital for Special Surgery knee score along with radiographs were used to evaluate preoperative and postoperative knee status, and the Cybex isokinetic test was used to assess muscle strength at the final follow-up. The average knee score improved from 64 points preoperatively to 90 points postoperatively (p < 0.05). The mean motion are of the knee improved from 108 degrees preoperatively to 116 degrees at the final evaluation. A total of 122 knees were pain free on walking and 130 knees were completely pain free at rest. A total of 134 knees achieved good to excellent clinical results. The radiographic results showed that the mechanical axis of the lower extremity was realigned from a mean of 12 degrees varus preoperatively to a mean of 1 degree varus postoperatively. No obvious radiolucent zones were found on the lateral view of the femoral components in 60.7% of the knees, or on the anteroposterior or lateral views around the tibial components in 49.3% and 82.9% of knees, respectively. The Cybex isokinetic test at the final follow-up examination revealed that the hamstring/quadriceps peak torque ratio was 0.8 at a speed of 60 degrees per second and 0.96 at 180 degrees per second, indicating that quadriceps muscle strength did not recover to within the range of healthy subjects. There were 23 (16.4%) complications, including polyethylene wear of patellar components (14), patellofemoral maltracking (4), septic loosening (2), aseptic loosening (2), and superficial infection (1). Revision surgery improved the functional outcomes in all of these knees. Based on our experience, we do not recommend the use of the MG I prosthesis in total knee arthroplasty (TKA) because of the high rate of patellar complications. Strengthening of the quadriceps must be emphasized in postoperative rehabilitation. Hybrid fixation might be a useful alternative fixation mode in TKA procedures.