Commentary & Perspective

Commentary & Perspective on
"Reduction of a Dislocation of the Hip Due to Developmental Dysplasia: Implications for the Need for Future Surgery"
by Scott J. Luhmann, MD, et al.

Commentary & Perspective by
Michael B. Millis, MD*,
Department of Orthopaedic Surgery, Children's Hospital, Harvard Medical School, Boston, MA

In the February issue of The Journal, Luhmann et al. addressed the important question of deciding the optimal timing of the reduction of dysplastic dislocated hips without a radiographically visible ossific nucleus at the time that the reduction is first considered. Prior studies have reached different conclusions: Segal et al.¹ found that reduction prior to the appearance of the ossific nucleus was associated with an increased prevalence of ischemic necrosis¹ while Luhmann et al.², in an earlier publication, reported that this earlier reduction was not associated with a significantly increased risk of ischemic necrosis. There is reason to believe that an ossific nucleus in the dislocated hip of an infant renders the femoral head and its blood supply somewhat less fragile when undergoing reduction¹. On the other hand, increasing age of the patient at the time of reduction of the dislocation has a strong negative association with the remodeling response of the proximal femur and acetabulum. Importantly, this response is prognostic of excellent long-term results of surgical management of hip dysplasia^2,3.

In the present study, the authors reexamined a previously reported series² in terms of the number of secondary operations that were required, with stratification of the patients according to both age and the presence or absence of the ossific nucleus at the time of reduction.

Of 153 hips (124 patients), sixty-three hips without an ossific nucleus (fifty-one patients; mean age at reduction, six months) were followed for an average of 7.5 years, and ninety hips with a visible ossific nucleus (seventy-three patients; mean age at reduction, 14 months) had an average duration of follow-up of 7.0 years.

There was a significant relationship between the patient's age at the time of reduction and the number of subsequent reconstructive procedures (p < 0.15). Only ten (17%) of fifty-nine hips in patients younger than six months of age had a subsequent reconstructive procedure in comparison with thirty-three (35%) of ninety-four hips in patients older than six months of age (p < 0.154) who had such procedures. In patients older than eighteen months at the time of reduction, seventeen (74%) of twenty-three hips had a subsequent reconstructive procedure. Neither the status of the ossific nucleus at the time of reduction nor a number of treatment factors independently examined correlated with the frequency of subsequent reconstructive procedures.

Luhmann et al. did recognize that the low frequency of ischemic necrosis and the relatively short follow-up may have not allowed for the determination of the role of ischemic necrosis in the occurrence of late deformity, which might necessitate secondary reconstructive procedures. All orthopaedists who care for patients with dysplastic hips recognize that the best information on which to base treatment decisions is derived from long-term studies of hips followed through skeletal maturity and beyond. The authors conceded that, with a longer follow-up, patients in both groups would need more secondary reconstructive procedures.

At present, it seems prudent to reduce the dislocation of the hip that is due to developmental dysplasia as soon as possible by the least traumatic method possible. One must recognize, as did Dhar et al.³, that "the iatrogenic complication of avascular necrosis in CDH [congenital dislocation of the hip] occurs after all kinds of treatment."

The vascular fragility of the dislocated femoral head in an infant should not be considered grounds for delaying reduction but should, rather, dictate the use of the most sophisticated contemporary methods of screening ^4,5, imaging, and, when necessary, operative treatment available to optimize outcomes in dislocations of the hip due to developmental dysplasia in patients of all ages^2,6.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Segal LS, Boal DK, Borthwick L, Clark MW, Localio AR, Schwentker EP. Avascular necrosis after treatment of DDH: the protective influence of the ossific nucleus. J Pediatr Orthop. 1999;19:177-84.
2. Luhmann SJ, Schoenecker PL, Anderson AM, Bassett GS. The prognostic importance of the ossific nucleus in the treatment of congenital dysplasia of the hip. J Bone Joint Surg Am. 1998;80:1719-27.
3. Dhar S, Taylor JF, Jones WA, Owen R. Early open reduction for congenital dislocation of the hip. J Bone Joint Surg Br. 1990;72:175-80.
4. Geva H, Bilalik V, Dimeglio A, Garinkol S. Concepts about prevention as defined by members of the European Pediatric Orthopaedic Society. J Pediatr Orthop B. 1993;2:104-7.
5. Graf R, Tschauner C, Klapsch W. Progress in prevention of late developmental dislocation of the hip by sonographic newborn hip "screening": results of a comparative follow up study. J Pediatr Orthop B. 1993;2:115-21.
6. Weinstein SL. Congenital hip dislocation. Long-range problems, residual signs, and symptoms after successful treatment. Clin Orthop. 1992;281:69-74.