Thirty-nine patients (43 hips) underwent cementless THA between April 2006 and March 2009 by using the medial protrusio technique. These patients participated in a 6- to 9-year follow-up. Their clinical and radiographic data were gathered prospectively.
The average Harris Hip Score improved from 43.1 ± 15.4 points preoperatively to 91.9 ± 12.8 points at the final follow-up (P < .001). The mean height of hip center and the distance of hip center medialization were 2.4 ± 0.6 and 2.5 ± 0.9 cm, respectively. The rate of medial protrusion and the rate of cup coverage were 42.1 ± 12.4% and 96.8 ± 5.1%, respectively. The rate of medial protrusion ranged from 18.3% to 58.3% in 38 hips (group A) and from 61.3% to 68.9% in 5 hips (group B). None of the cups in group A loosened or failed, 2 failures occurred in group B (0% vs 40.0%; P = .011).
Developmental dysplasia was treated through THA using the medial protrusio technique, which easily achieves a sufficient superolateral host bony coverage of the cup and promotes socket reconstruction at the true acetabulum. The rate of medial protrusion of <60% may be necessary to obtain excellent clinical and radiographic midterm results.