Clinical results of unicompartmental arthroplasty for knee osteoarthritis using a tibial component with screw fixation

Abstract

Unicompartmental knee prostheses with screw fixation into the proximal tibia were employed and postoperative clinical results for osteoarthritis of the knee, especially regarding relief of pain, range of motion and satisfactory limb alignment are reported and discussed. A total of 140 knees (131 medial and 9 lateral) of 85 patients (21 men and 64 women) were followed up for two to 17 years with an average of 7.0 ± 3.0 years. In spite of loss to follow-up in three knees of two patients and revision to total knee arthroplasty in one knee of one patient, in the remaining 136 knees (82 patients) the mean knee score of the Knee Society Clinical Rating System was 41.0 ± 14.7 pre-operatively, which improved to 93.1 ± 5.7 at follow-up, while the mean functional score similarly improved from 36.9 ± 8.1 to 88.5 ± 6.3 (p < 0.001 respectively). One knee developed a fracture in the medial proximal part of the tibia, but no knee developed loosening of the prosthesis or infection. The mean pre-operative knee flexion was 122.6 ± 15.9°, which improved to 132.9 ± 13.4° (p < 0.001) at follow-up. The limb alignment showed 4.8 ± 4.5° anatomical varus angulation pre-operatively, which was corrected to 5.8 ± 3.3° valgus at follow-up in the medial unicompartmental replacement group (127 knees), and 19 ± 6.1° valgus pre-operatively, which was corrected to 6.7 ± 3.0° valgus at follow-up in the lateral unicompartmental replacement group (nine knees). The clinical results of arthroplasty with screw fixation were concluded to be promising.