Petit-Morel method for hip development dysplasia in toddlers: A retrospective observational study in 34 patients

Abstract

Background: The Petit-Morel method allows the treatment of developmental hip dysplasia in toddlers by combining gradual traction to achieve reduction followed by immobilisation during which pelvic osteotomy is performed. The objective of this study was to assess the radiographic and clinical outcomes in a retrospective cohort of patients.

Hypothesis: The Petit-Morel method is associated with low rates of avascular necrosis and residual acetabular dysplasia at skeletal maturity, as well as with satisfactory medium-term clinical outcomes.

Material and methods: We conducted a single-centre retrospective study of 34 patients (35 hips) treated between 1997 and 2014. The radiological assessment criteria included an evaluation for avascular necrosis classified according to Kalamchi and MacEwan, the vertical centre edge (VCE) angle, femoral head sphericity according to Mose, and acetabular dysplasia at skeletal maturity according to Severin. Hip function was assessed by determining the Postel-Merle d'Aubigné (PMA) score.

Results: Mean age at treatment was 19±4 months (range, 14-29). Mean follow-up was 11 years (range, 5-20). There were two failures including one case of recurrent dislocation requiring surgical reduction. Group II avascular necrosis occurred in 1 (3%) patient. Tönnis Grade IV dysplasia was significantly associated with resolving irregularity of the ossification centre, seen in 19 (54%) cases (p=0.002). In the 18 patients followed-up to skeletal maturity, with a mean follow-up of 15 years (range, 12-20 years), 17 hips were Severin Class I. The mean VCE angle was 29° (range, 15°-38°), and the head was spherical for 34 (98%) hips. The PMA score at last follow-up was excellent (17-18). The mean VCE angle was greater in all 5 patients who experienced pain during long walks (35° [range, 32°-37°]) than in the asymptomatic patients (28° [range, 15°-38°]) (p=0.009).

Discussion: The Petit-Morel method is a reliable treatment that provides good clinical and radiological outcomes. Overcorrection of the VCE angle was noted in the patients who experienced walking-related pain in adulthood.

Level of evidence: IV, retrospective observational cohort study.

Keywords: Closed hip reduction; Developmental dysplasia of the hip in toddlers; Petit-Morel method; Salter innominate osteotomy.