Abstract
Aims: This report analyzes the inßuence of the postoperative deformity on the risk of loosening, recurrence of the deformity and progressive osteoarthritis in the remaining femoro tibial compartment. Methods: Between 1978 and 1988, 156 medial cemented uni-compartmental arthroplasties were performed in 142 patients. Alignment was measured postoperatively as the hip-knee-ankle (H.K.A.) angle on radiographs of the whole limb. Of these 156 knees, 132 retained the original implants until the patient died or until the most recent follow-up examination, eight were lost to follow-up and revision was performed in sixteen knees. 58 implants that were in patients still alive at least 10 years were evaluated clinically and for radiographic changes and limb alignment at the time of their most recent follow-up. Results: An overcorrection in valgus of the deformity (H.K.A. angle > 180 degrees) was associated with a risk of degenerative changes in the opposite compartment and revision (3 revisions among these 15 knees). Severe undercorrection in varus of the deformity (H.K.A. angle less than 170 degrees) was associated with a risk a loosening of the tibial component in the long term: (12 revisions among 50 knees). The best results were obtained in the ninety-one medial implants that were implanted in moderate varus with a postoperative H.K.A. angle of 171 to 179 degrees (one revision for loosening among these 91 implants). The varus deformity tended to recur at the latest follow-up; this change in alignment was indicative of polyethylene wear. Conclusions: Overcorrection in valgus of the preoperative deformity increased the risk of disease progression in the contralateral
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
