Is the Transverse Acetabular Ligament Hypertrophied and Hindering Reduction in Developmental Dysplasia of Hip?

Purpose: To investigate the arthroscopic pathoanatomy of the transverse acetabular ligament (TAL) and determine whether a TAL incision is necessary for the concentric reduction of developmental dysplasia of the hip (DDH) in infants and young children. Methods: We retrospectively reviewed patients who underwent arthroscopic-assisted reduction for DDH between July 2008 and April 2016. The indications for this intervention included patients in whom closed reduction failed and those who did not require bone operations. The arthroscopic findings and the effect of the TAL incision on DDH reduction were evaluated. TAL pathology was apparent when it was pulled superiorly or hypertrophied. Results: We identified a consecutive series of 13 patients (13 hips). Two patients with teratologic dislocation were excluded. There were 9 girls, 8 first-born infants, and 3 breech-position infants. Six patients showed positive Ortolani test findings. In all cases the TAL was considered not hypertrophied when it appeared as a narrow, cord-like structure that was continuous and in smooth transition with the TAL-labral ring, without prominence or elongation. All postreduction magnetic resonance imaging scans showed reduced femoral heads; however, residual subluxation was observed in 8 of 11 hips owing to the interposed anteroinferior labrum. On arthrography at 6 weeks after reduction, the femoral head was located deeper in the acetabulum and the medial dye pool width was within 2 mm in all patients. Conclusions: The TAL was not observed to be hypertrophied or stretched in any of the DDH patients, and it did not act as an obstacle to reduction. After the TAL incision, the gap of the cut margin was not remarkably widened, although there were varying degrees of release. The incision of the TAL does not appear to result in the immediate alteration of the TAL-labral ring in favor of deeper acetabular seating or to enhance reduction.