The Presence of an Ossific Nucleus Does Not Protect Against Osteonecrosis After Treatment of Developmental Dysplasia of the Hip

Abstract

Background Osteonecrosis (ON) is a major complication after treatment of developmental dysplasia of the hip (DDH). Several studies have explored the absence of the femoral head ossific nucleus at the time of hip reduction as a risk factor for the development of ON, but findings have been inconsistent. Questions/purposes We therefore determined the incidence of ON in children who underwent reduction of a dislocated hip in the presence or absence of the ossific nucleus. Patients and MethodsWe retrospectively reviewed the radiographs of 105 hips in 89 patients treated for DDH at the age of 18 months or younger. Radiographs were graded for the presence of the ossific nucleus at the time of hip reduction and for the presence of ON, as graded by the Bucholz and Ogden classification, for patients at a mean age of 10 years. We used log-binomial regression to estimate if the presence of the ossific nucleus was associated with a lower incidence of ON. Results We identified ON in 37 of the 105 hips (35%). The incidence of ON at 10 years was 40% in the absence of the ossific nucleus and 32% in the presence of the ossific nucleus (adjusted relative risk, 0.86; 95% confidence interval, 0.36-1.81). When only radiographic changes of Grade II and greater were considered ON, the risk was still not increased (relative risk, 1.26; 95% confidence interval, 0.62-2.56). Conclusion Patients with an ossific nucleus at the time of hip reduction showed a slight tendency toward better outcomes. The ossific nucleus did not protect for ON. Level of Evidence Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Does Perfusion MRI After Closed Reduction of Developmental Dysplasia of the Hip Reduce the Incidence of Avascular Necrosis?

“…We found no difference in abduction angle with the numbers available in either those who developed AVN or those displaying abnormal enhancement on pMRI. Consistent with prior studies, gender [3], laterality [3], previous treatment with a Pavlik harness/abduction brace [3,18,24], and concurrent procedure [18] all had no effect on final AVN rates with the numbers available in our cohort. The presence or absence of the ossific nucleus at the time of reduction remains a controversial issue.…”

“…In their review of the literature, Cooper et al [8] found a wide range in reported AVN rates between 3% and 60%, which they attributed to variations in the definition of AVN and the length of followup. In a more recent sample [4,6,7,16,19,21,24,30,34], AVN rates varied more consistently between 7% and 36%, but again a wide variety of radiographic criteria was used to identify AVN. In this study, we used Salter criteria as did Tiderius et al [34].…”

“…To date, however, no study has evaluated the effectiveness of pMRI as a primary decision-making tool or compared it with other approaches (such as postreduction CT scan) to show a difference in AVN rate or other clinical outcomes. As a result of the long-term disability associated with AVN, and the mixed success of closed reduction [6,18,24], the role of closed reduction/spica casting in the management of DDH has recently been questioned. If a pMRI-based protocol proves helpful, its use might allow the surgeon to critically evaluate the quality of reduction while simultaneously minimizing the risk for future AVN and therefore improve the results of closed reduction procedures.…”

Is Age or Surgical Approach Associated With Osteonecrosis in Patients With Developmental Dysplasia of the Hip? A Meta-analysis

“…Previous studies proposing delaying the treatment of DDH hypothesized that the development of the microcirculation in the femoral head, concomitant with the radiographic appearance of the ossific nucleus, would protect against osteonecrosis [16,75]. However, other studies [21,53,70] did not find older age and the presence of ossific nucleus as protective factors for osteonecrosis. Those opposing delaying treatment would further ague that it could potentially compromise acetabular remodeling, whereas early reduction may prompt better development of a congruent hip [22].…”

Reliability of Bucholz and Ogden Classification for Osteonecrosis Secondary to Developmental Dysplasia of the Hip

“…We realized in previous studies [12][13][14]16] that classifying hips as described by Bucholz and Ogden [1] can be challenging and confusing with questionable reliability. Reliability, or reproducibility, is a prerequisite of any scientific measure.…”