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