Radiological results of the Bernese periacetabular osteotomy performed before closure of the triradiate cartilage.

Aims: The Bernese periacetabular osteotomy (PAO) is typically not performed until after the growth plates have closed in late adolescence, as the osteotomy crosses the posterior branch of the triradiate cartilage, which could potentially cause deformities similar to post-traumatic dysplasia, a condition observed following pelvic fractures in childhood. The aim of this study was to retrospectively analyze on radiographs whether the PAO, when performed in children with open growth plates, affects acetabular development.

Methods: We retrospectively reviewed the radiological outcomes of 23 hips (20 patients) with a mean age of 10.7 years (SD 1.8; 5.7 to 12.7). Preoperative, three-months postoperative, and latest follow-up measurements (after growth plate closure) were assessed for the following parameters: lateral centre-edge angle (LCE), acetabular index (AI), head extrusion (HE) index, femoral head (FH) lateralization, and teardrop thickness. We also compared the age at triradiate cartilage closure between the operated and nonoperated hips.

Results: The mean follow-up was 5.2 years (SD 3.7; 0.6 to 12.7). Preoperatively, over 80% of the hips showed pathological measurements, which improved significantly post-PAO. None of the hips had pathological measurements after surgery. All acetabular angles showed significant improvement post-PAO (LCE from 14° (SD 8°) to 38° (SD 11°); AI from 20° (SD 8°) to 7° (SD 4°); and HE index from 32° (SD 9°) to 8° (SD 8°)). Acetabular moulding was physiological with little FH lateralization (from 9° (SD 9°) to 11.7° (SD 4.8°)), and a small increase in teardrop width (4.7 mm (SD 1) to 8.2 mm (SD 4.4)). Few complications were observed: one case of osteoarthritis (OA); one case of transient sciatic nerve irritation that resolved; one case of interfering osteosynthesis material that was removed; and one case requiring an additional valgus intertrochanteric osteotomy. All complications resolved without further issues.

Conclusion: Our data on the use of PAO in patients with an open growth plate are encouraging with normalization of acetabular coverage parameters and only minor alterations of acetabular development, and may support its use in children six years old and older.