[Triple osteotomy (modified Tönnis method) for advanced coxarthrosis]

The results of 79 triple osteotomies (modified Tönnis method) for advanced coxarthrosis in 76 patients, performed between 1986 and 1991 in our clinic, were evaluated. The operation was performed for 72 females and 4 males, with a mean age of 45.6 years, ranging from 20 to 59 years. The mean follow-up period was 4 years and 2 months, ranging from 1.6 to 9 years. The operative technique used was a modified Tönnis method originally described by Tönnis in 1981. Using a dorsal approach, the ischium is first osteotomized and then turning the patient to the supine position, the osteotomies of the pubis and ilium are performed through an anterior approach. The osteotomized acetabulum is rotated antero-laterally as much as possible to cover the femoral head sufficiently and is fixed with 4 or 5 Steinmann pins. For the clinical evaluation, we used the Japanese Orthopaedic Association Hip Score. The average score improved from 68 points preoperatively to 90 points postoperatively. The roentogenological evaluation confirmed the following results; excellent in 36 hips (46%) with good joint space and good joint congruity, fair in 35 hips (44%) with good joint space and fair joint congruity, and poor in 8 hips (10%) with narrowed joint space. The average CE angle at follow-up was 40.3 degrees in 36 hips with excellent result, 33.8 degrees in 35 hips with fair, and 32.4 degrees in 8 hips with poor (p < 0.01). Good remodelings are obtained, if the CE angle becomes more than 40 degrees postoperatively in acetabular rotational osteotomy for advanced coxarthrosis.