Is the Bernese Periacetabular Osteotomy Safe for the Treatment of Acetabular Dysplasia When the Triradiate Cartilage is Still Open? A Preliminary Study.

Background: Periacetabular osteotomy (PAO) has historically been contraindicated in children with hip dysplasia and open triradiate cartilage because of concerns that osteotomy through the triradiate might disrupt acetabular development. This preliminary study reports early outcomes of PAO for hip dysplasia in patients approaching skeletal maturity (aged 8 to 12 y or younger) with open triradiate cartilage.

Methods: We performed a retrospective review of patients with hip dysplasia and open triradiate cartilage who underwent PAO between 1994 and 2019. Primary outcomes included changes in lateral center edge angle (LCEA), anterior center edge angle (ACEA), and acetabular index (AI), discontinuity along Shenton's line, extrusion index, triradiate width, and Tonnis grade preoperatively, postoperatively, and at final follow-up. Secondary outcomes included comparisons of radiographic parameters between the operative hip and the contralateral nonoperative hip, preoperative and postoperative patient-reported outcomes, and complications, including intraoperative intra-articular fractures, osteotomy nonunion, and premature triradiate closure. Descriptive statistics characterized the study population. Linear mixed-effects regression models and Cochran Q tests compared clinical and radiographic outcomes preoperatively, postoperatively, and at final follow-up. Differences between operative hips and contralateral nonoperative hips were analyzed using paired t tests or Wilcoxon signed-rank tests.

Results: Thirteen patients were included. The mean age was 11.04 years (range: 8.05 to 12.82 y), and the mean follow-up was 3.79 years (range: 0.51 to 8.39 y). The mean LCEA increased 21.08 degrees immediately after PAO (preoperative 5.61±10.41 degrees; postoperative 26.69±8.82 degrees; P <0.01). This change was maintained at final follow-up (23.14±9.14 degrees; P <.01). Premature triradiate closure occurred in 5/13 patients (38.5%). No hips progressed in Tonnis Grade during the study period. Neither intra-articular fracture nor osteotomy nonunion was noted.

Conclusions: This preliminary study demonstrates that PAO can safely treat hip dysplasia in young adolescents with open triradiate cartilage, with good short-term outcomes. Despite premature triradiate closure in 38%, immediate postoperative correction of acetabular dysplasia remained satisfactory at final follow-up. Further studies are warranted to determine long-term outcomes.

Level of evidence: Level IV-case series.