TRANSTROCHANTERIC ROTATION OSTEOTOMIES FO R OSTEONECROSIS (20 CASES)

Purpose of the study Twenty consecutive rotation osteotomies for idiop atic necrosis of the femoral head were reviewed with an average follow -up of 6,5 years, in order to evaluate an original technique (which us es a nail plate for rotation and fixation of the fragments), and to de termine the middle term results (and therefore indications) of anterio r and posterior rotation osteotomies. Materials and methods Technique : rotations were achieved by rotating the femoral head with the nail o f the nail plate, and without dissection of the posterior vascular bun dle. We performed 16 anterior rotation osteotomies (according to Sugio ka, with an average rotation of 52 degrees) and 4 posterior rotation o steotomies (described by Kempf, with an average rotation of 77 degrees ). Only two patients were lost after 2 years follow-up (with good resu lt), and the radio-clinical outcome of 18 operations at 5 years was kn own. Results Global results were : 7 failures, 3 fair and 10 very good or good. In the 4 posterior rotations (Kempf) we achieved 4 very good results, even in Ficats stage 3. In the 16 anterior rotations we coul d in all cases obtain, on the hip in extension, an almost complete dis charge of the necrotic zone, as after osteotomy it was no more in fron t of the acetabular major bearing zone (defined as an angle of 40 degr ees around the apex of the femoral head on the lateral Lequesne view). We obtained 6 good and very good results, 3 fair, and 7 failures requ iring a THR. There were 2 factors of poor prognosis : Stage of the nec rosis, as we observed 4 failures in the 4 Ficat's stage 3, and only 3 failures in the 12 stage 2. Depth of the necrosis, as we achieved 6 ve ry good and good results and 1 poor in the 7 cases when it was no more than 1/3 of the head diameter. But in the 9 cases where depth was ove r one third there were 3 fair and 6 poor results. Discussion Our techn ique proved to be reliable as it achieved the rotation planned before operation (only one hypo-correction of 15 degrees) and bone fusion, al lowing full weight bearing at 3 months in all cases. No extension of t he necrotic area was observed. Posterior rotation osteotomy was follow ed by long term favorable results, may be because it achieves an anato mic discharge of the necrotic zone not only when the hip is in extensi on, but also when the hip is flexed. Anterior rotation is only recomme nded when : a rotation not exceeding 60 degrees (therefore without ris ks for the posterior bundle) allows a discharge of the necrotic zone w hen the hip is in extension. the necrosis is stage 2. In Stage 3 a pro gressive arthritis may occur as, in hip flexion, the necrotic sector o f the non spherical head comes in front of the acetabular major bearin g zone. the depth of the necrosis does not exceed 113 of the femoral h ead, such as in cases of a very large necrosis, mechanical degradation of the non necrotic part of the head may occur, even if discharge of the necrosis is achieved. Conclusion Transtrochanteric rotation osteot omy may delay of a decade or more the occuring of osteoarthritis, if i ts indications are restricted to patients under 40, suffering from idi opatic necrosis. In our series Sugioka osteotomy gave good results in stage 2 when necrosis depth was no more than 1/3 of the head diameter. Posterior osteotomy allows a better discharge of the necrotic zone an d thus may be proposed in less restricted conditions.