Isolated Trochanteric Descent and Greater Trochanteric Apophyseodesis Are Not Effective in the Treatment of Post-Perthes Deformity.

BACKGROUND

Greater trochanteric apophyseodesis and isolated trochanteric descent seek to prevent abductor weakness in patients with a hip deformity because of Legg-Calvé-Perthes disease; however, no studies have evaluated radiographic findings or abductor strength in children treated with these procedures.

QUESTIONS/PURPOSES

(1) Do children with Waldenström Stage III Legg-Calvé-Perthes disease treated with either isolated greater trochanteric descent or isolated greater trochanteric apophyseodesis achieve improved radiographic findings (Stulberg classification or neck-shaft angle) compared with those who underwent no surgical treatment? (2) Do children treated with one of those procedures achieve greater abductor strength than those who did not have surgery?

METHODS

Between 2006 and 2010, we treated 89 children with Waldenström Type III Legg-Calvé-Perthes disease (reossification). Of these, 27.9% (12 patients) underwent greater trochanteric descent, 25.6% (11 patients) underwent greater trochanteric apophyseodesis, and 46.5% (20 patients) did not have surgery. During that time, the decision to perform either apophyseodesis or trochanteric descent was made by the surgeon based on the subjective appearance of remaining growth from the greater trochanter. Nonsurgical management was chosen by the parents of the patients after the risks and benefits of surgery were discussed. During greater trochanteric descent, the greater trochanter was osteotomized and fixed distally with two 7.0-mm screws. During greater trochanteric apophyseodesis, the physis was identified fluoroscopically, and the lateral half of the growth plate was drilled. Nonoperative treatment involved serial clinical and radiographic evaluations every 3 to 6 months. All children in all groups were available for follow-up at a minimum of 6 years. The median follow-up durations for children undergoing greater trochanteric descent, greater trochanteric apophyseodesis, and control cohorts were 6.6 years (range 6.0-8.2 years), 6.5 years (range 6.1-9.2 years), and 7.4 years (range 6.0-9.1 years), respectively. On presentation, each patient's affected hip was classified according to the Stulberg classification by the operating surgeon and an orthopaedic surgeon not involved in the child's care. The neck-shaft angle was measured for each patient before surgery and at the final follow-up examination. Abductor strength was assessed by a pediatric orthopaedic fellow and a physical therapist with the patient in the lateral decubitus position. Each patient was given a muscle strength score on a scale of 0 to 10 points, per a modification of the Medical Research Council scale to allow for a narrower range. We had 80% power to detect an 8° difference in the neck-shaft angle between the greater trochanteric apophyseodesis and nonoperative management cohorts. A sample size of 6.8 patients per cohort would be necessary to detect the above endpoint.

RESULTS

With the numbers available, we found no differences among the groups in the proportion of patients with Stulberg Class 2 femoral heads (two of 12 patients in the isolated trochanteric descent group, three of 11 in the isolated trochanteric apophyseodesis group, and two of 20 who did not undergo surgery; p = 0.46). Likewise, there were no differences among the three groups in terms of the neck-shaft angle at a minimum of 6 years of follow-up (122° ± 6°, 119° ± 7°, and 126° ± 8° in the isolated trochanteric descent, isolated trochanteric apophyseodesis, and nonoperative groups, respectively). There were no differences among the groups in term of the median abductor strength test result: seven of 10 (range 6-8), six of 10 (range 6-8), and six of 10 (range 6-10; p = 0.34).

CONCLUSION

Because neither isolated greater trochanteric descent nor greater trochanteric apophyseodesis alone had an effect on hip morphology or abductor strength in children with sequellae of Legg-Calvé-Perthes disease, we conclude these types of extraarticular surgery are ineffective. Therefore, we no longer perform isolated trochanteric descent or apophyseodesis.

LEVEL OF EVIDENCE

Level III, therapeutic study.