TO THE EDITOR:
I read with great interest "Long-Term Outcome after Open Reduction through an Anteromedial Approach for Congenital Dislocation of the Hip" (79-A: 810—817, June 1997), by Morcuende et al. Although the authors considered the anteromedial approach to be useful for the treatment of congenital dislocation of the hip, they expressed concern about the unexpectedly high rate of growth disturbances of the femoral head; the overall rate of avascular necrosis in their study was 43 per cent (forty of ninety-three hips), and the rate of type-II avascular necrosis, according to the classification of Bucholz and Ogden1, was 24 per cent (twenty-two of ninety-three hips). The causes of these growth disturbances are extremely controversial. Failure of treatment before open reduction is regarded as one cause. However, the authors could not find any significant difference between hips that had had previous treatment and those that had not.
It is worth noting that a high percentage of femoral heads (47 per cent; forty-four of ninety-three hips) were found to be deformed at the time of the operation. The authors omitted this important evidence of avascular necrosis from their analysis. The fate of these forty-four deformed femoral heads should have been addressed. It is my impression that the high prevalence of growth disturbances may be attributed to the initial unsuccessful treatment rather than to the outcome of the anteromedial reduction.
Zvi Yosipovitch, M.D.: 44 Tagor Street, Tel Aviv 69341, Israel
Dr. Morcuende, Mr. Meyer, Ms. Dolan, and Dr. Weinstein reply:
We appreciate Dr. Yosipovitch's interest and comments regarding our manuscript. We addressed the fate of the hips in which a deformity of the femoral head was discovered at the time of the operation in the section "Association between Pre-Reduction Clinical Parameters and Outcome Variables." As we described, with the number of patients available for study, we did not find the degree of sphericity of the femoral head to be significantly associated with growth disturbances of the femoral head or with the most recent Severin classification2.
With respect to his consideration of this pre-reduction deformity of the femoral head as evidence of avascular necrosis, it was difficult for us to ascertain whether the deformity was the result of vascular compromise or an increase in the contact area between the femoral cartilage and the superolateral aspect of the acetabulum or the wall of the ilium. Although roentgenographic eccentricity and irregularities of the ossified femoral nucleus may be interpreted as consistent with vascular compromise, to our knowledge, no anatomical or histopathological studies have been performed to examine this hypothesis. Therefore, this important question may remain unanswered.
José A. Morcuende, M.D., Ph.D.; Mark D. Meyer, M.A.; Lori A. Dolan, R.N., M.A.; Stuart L. Weinstein, M.D.: Department of Orthopaedic Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242-1088