O2143: Arthrography in DDH – What factors influence poor quality arthrograms?

Background: The hip arthrogram is invaluable in managing developmental dysplasia of the hip (DDH). Arthrography can assist orthopedic surgeons in deciding between closed or open reduction and in monitoring for a concentric, congruent, and stable reduction. However, performing and interpreting arthrograms is often challenging. Therefore, the purpose of this study was to define patient and operative characteristics that predict a “poor quality” arthrogram following prior open or closed reduction.

Methods: We identified patients treated with anterior or medial open reduction who subsequently returned to the operating room for an arthrogram, with or without cast changes. We then randomly selected an equivalent number of patients who underwent closed reduction between 1987 and 2022. Arthrograms performed at the time of index reduction and at subsequent encounters were analyzed. Each arthrogram was graded as excellent, good, fair, or poor based on the criteria listed in Figure 1. Reduction quality was graded as follows: 1) Concentric reduction, medial dye pool < 16% of the femoral head diameter, and no infolded limbus 2) Concentric reduction with medial dye pool >16% or visible interposition of pulvinar or ligamentum teres and/or infolded limbus 3) Non-concentric reduction. Patient characteristics and operative data were analyzed for their association with “poor” quality arthrograms.

Results: 79 open reductions and 79 closed reductions were identified, with a mean age at reduction of 1.15 ± 0.9 years, and 89% of patients were female. The mean time from reduction to arthrogram was 6.5 ± 1.2 weeks. Open reduction was performed via a medial approach in 43 cases (54.4%) and anterior approach in 35 cases (44.3%), with 14 patients (18%) undergoing a concomitant pelvic osteotomy. Patients with a lower weight percentile were associated with poorer arthrogram quality (36.9%ile vs 64.6%ile, p = 0.0007). Open reduction performed via the anterior approach were more likely to have a subsequent poor arthrogram when compared to medial open reduction and closed reduction (17.1% vs 0.0% vs 10.1%, p = 0.011). Additionally, a previous concomitant pelvic osteotomy was associated with poor arthrogram quality (28.6% vs 3.1%, p = 0.008).

Conclusion: The hip arthrogram is valuable for visualizing hip reductions. Poor quality arthrograms were associated with lower weight percentile, prior anterior open reduction, and the presence of a concomitant pelvic osteotomy at index open reduction. These findings may be useful for educating resident orthopedic surgeons about cases that may present additional challenges.