The fate of inverted limbus in children with developmental dysplasia of the hip: Clinical observation

Abstract

In this study, we observed the fate of the inverted limbus after closed reduction for the treatment of developmental dysplasia of the hip (DDH) and its impact on acetabular development. Clinical data were reviewed for 26 DDH patients with an inverted or overriding limbus after closed reduction for hip dysplasia. Patients were divided into a residual inversion group (19 cases, 22 hips) and a spontaneous resolution group (7 cases, 7 hips) according to the limbus status at the last follow‐up. Differences in the osseous acetabular index (AI) and cartilaginous AI (CAI), the magnitude of limbus inversion, center‐edge angle (CEA), height‐to‐width index (HWI) of the femoral head epiphysis, and avascular necrosis (AVN) at last follow‐up were compared. There were no statistically significant differences in the preoperative AI and CAI between groups. The magnitude of limbus inversion after reduction and the AI at the final follow‐up in the residual inversion group were both larger than those in the spontaneous resolution group. The CAI, CEA, and HWI were not significantly different between groups. The magnitude of limbus inversion in the residual inversion group did not significantly decrease over time. AVN occurred in five hips in the residual inversion group. No cases of AVN occurred in the spontaneous resolution group. After closed reduction, the inverted limbus was not absorbed in the majority of cases; instead, it evolved into a thin layer of fibrous tissue embedded between the femoral head and acetabulum. This may delay the endochondral ossification of the acetabulum.

Acetabular development and fate of inverted limbus in rabbits: Experimental observation from an animal model

“…While the limbus may remain inverted following closed reduction, few studies have investigated the long‐term effects of this phenomenon. In our previous clinical studies, 4 midterm follow‐ups of patients who had undergone closed reduction for DDH indicated that limbus inversion could delay acetabular ossification. Nonetheless, the long‐term effects of limbus inversion remain unknown.…”

“…Our previous clinical studies indicated that 4 following closed reduction for DDH, part of the inverted limbus does not completely disappear. Instead, it evolves into a thin layer of fibrous tissue interpositioned between the acetabulum and the femoral head.…”

“…This finding is in accordance with imaging findings reported in other studies on OA due to limbus inversion, 5 which showed a possible delay in ossification of the acetabulum. However, because patients were not followed up until bone maturity in our clinical study, 4 we were unable to obtain imaging evidence of the OA. Given that closed reduction does not allow for the collection of tissue samples for morphological and molecular analyses, this present study aimed to establish an animal model of limbus inversion.…”

The Clinical Significance of Infolded Limbus on Postreduction Arthrogram in Developmental Dysplasia of the Hip

“…Interestingly, Liu et al 10 and Zhou et al 9 reviewed MRI following closed reduction and noted a much higher rate of inverted limbus (83% and 77%, respectively). These differences may be due to differences in the population presenting to our respective centers or to an increased sensitivity of MRI in detecting infolded limbus.…”

“…The limbus is a pathologic structure composed of the labrum and hypertrophic cartilage of the superolateral acetabulum in dislocated hips that may block reduction and may either evert or invert on reduction. [8][9][10] Forlin et al 11 noted that infolded limbus was associated with increased rates of residual dysplasia or hip subluxation/redislocation. However, many of these patients also had significant lateralization of their femoral heads on initial reduction which may have confounded these results.…”