Effectiveness of abduction orthosis for the treatment of acetabular dysplasia.

Objectives: This study aims to evaluate the effectiveness of full-time bracing in residual acetabular dysplasia (RAD) and the effect of previous Pavlik harness usage on the results of treatment with abduction orthosis.

Patients and methods: We retrospectively reviewed 80 patients (9 males, 71 females; mean age 6±0.8 months; range, 5 to 7 months) with developmental dysplasia of the hip (119 dysplastic hips) treated with hip abduction orthosis. Patients with an acetabular index (AI) measurement of 30° and over who used full-time hip abduction brace for six months were included in the study. Acetabular index values were measured at the initiation, third, and sixth months of treatment and the effectiveness of abduction orthosis was evaluated. The patients were analyzed for the effect of prior Pavlik harness application on abduction orthosis treatment.

Results: Mean AI value of the dysplastic hips (n=119) was 33.4°±2.6°, which decreased to 28.5°±2.6° after treatment (p<0.001). The AI improvement in the first three-month period was significantly faster than the second three-month period (2.9°±1.9° vs. 1.9°±1°; p=0.013). No difference was observed in AI development between patients with or without prior Pavlik treatment (p=0.1). In patients with unilateral dysplasia, dysplastic hips improved significantly faster than normal hips (p<0.001). As a result of a mean follow-up duration of 20.2±9.8 months from the onset of brace treatment, 32 (32%) hips were grouped as normal, 49 (48%) as mildly dysplastic, and 22 (20%) as severely dysplastic based on Tönnis criteria.

Conclusion: Hip abduction orthosis may be used in patients with RAD between 6 to 12 months of age. Acetabular index improvement was faster in the first three months of brace treatment. Dysplastic hips improved faster than normal hips, and prior Pavlik harness treatment did not alter the effectiveness of orthosis.