OPERATIVE THERAPY OF SEQUELS AFTER NECROSIS IN DDH

Abstract

Postdysplastic ischaemic necrosis of the proximal femoral epiphysis has its origin in the vascular crisis during conservative or operative treatment of DDH and in the majority of cases has an iatrogenic origin. The severity of the symptoms and functional disability is dependent on the anatomic changes of the proximal femur and the whole hip joint respectively, which were caused by previous conservative or operative treatment, including repeated surgery. The symptoms such as limping from leg length discrepancy and abductor insufficiency, pain and restricted ROM are less apparent in small children, but become more conspicuous with the approach of the end of growth. For the classification of the patterns of ischemic necrosis of the femoral head, the classification according to Bucholz and Ogden was used.

Four principal types of this deformity are recognised. There are three main problems which are to be solved by surgical treatment. 1. The acetabular dysplasia with a pelvic osteotomy 2. Improving the bio-mechanics by distalisation of the greater trochanter and by the lengthening of the femoral neck with or without valgisation 3. Lengthening of the shorter extremity.

The decision on the type of surgery to be performed depends on the age of the patient and the severity of the anatomic deformity, as well as the functional disability. A very useful method for treatment was found to be a double intertrochanteric osteotomy with a trochanteric advancement, and almost invariably in combination with a triple or Salter pelvic osteotomy. The lengthening osteotomy of the femoral neck follows the principles of Müller and Wagner. A similar technique was also proposed later by Morscher.

My own contribution has been to modify the operation by an oblique execution of the osteotomy, and a method of fixation of the greater trochanter by means of an angle plate – providing a lengthening of the limb by up to 3 cm. In the case of acetabular dysplasia, a pelvic osteotomy should be performed as a first procedure in order to obtain better stability of the hip joint. A femoral osteotomy can follow at a minimal interval of three months. If the femoral osteotomy is performed as a first step without enlargement of the actabulum, there is the risk of further deterioration of the covering of the femoral head, even in a dislocation. This philosophy of treatment of sequel of postdysplastic necrosis has been used since 1979.

Up to 1984, we operated on 48 hip joints in 46 patients, 39 girls and 7 boys aged 4 to 21, with a follow- up of at least 15 years. In 12 cases, 10 girls and 2 boys aged 4 to 8, a Salter and valgus osteotomy was performed. Thirty-four patients (29 girls and 5 boys) had a triple pelvic osteotomy, with 2 girls being operated bilaterally. In 22 hips, a lengthening osteotomy of the femoral neck was added as a second stage procedure. Five parameters were used for clinical evaluation: pain, limping, range of motion, Trendelenburg sign, and leg length discrepancy. For radiological assessment, we used an AP X-ray of the entire pelvis taken before and after osteotomy, and also during follow-up. CE angle, Sharp’s angle, ACM angle, and lateralisation were recorded. Hip score was measured on all hips, but we found that CE, Sharp and lateralisation were of greater value. In a group of 12 cases operated on up to the age of 8 by combining Salter and valgus osteotomy, a cementless THR was necessary for a young woman of 25. The remaining 11 patients are up to the present time without any major problems. In a group of 14 patients operated for sequel of postdysplastic necrosis Type II deformity (all with triple pelvic osteotomies and five in combination with femoral neck lengthening osteotomy), all have a normal quality of life, including having natural childbirths. From 22 Type III hip joints in 20 patients operated for sequel of postdysplastic necrosis, a cementless THR was implanted in three cases 14, 17 and 18 years after original surgery. Fourteen patients (15 hip joints − 67%) can be considered as good results without needing to have any therapy. Three patients (4 hips) suffer from degenerative arthritis and are candidates for THR.