Risk factor analysis of recurrent subluxation after Pemberton and proximal femur osteotomy in infancy and childhood with developmental dysplasia of the hip

Objective To investigate the risk factors of recurrent subluxation after Pemberton and proximal femur osteotomy with developmental dysplasia of the hip(DDH)in infancy and childhood. Methods From January 2004 to December 2007, 62 patients (79 hips) of DDH in infancy and childhood were treated with Pemberton and proximal femoral subtrochanteric shortening and varus and derotation individualized osteotomy were evaluated at a minimum follow up of 10 years. The average age was (4.28±2.13)years old before the operation, 17 hips of bilateral dislocation and 45 hips of unilateral dislocation, 23 patients (33 hips) were younger than 3 years and 39 patients (46 hips) were older than 3 years, according to Tonnis classification, 16 hips, 19 hips and 44 hips were graded asⅡ, Ⅲ and Ⅳ respectively. Pearson contingency coefficient was used to analyze the correlation between gender, age, Tonnis classification, unilateral/bilateral hip, avascular necrosis(AVN) and recurrent subluxation, Mckay clinical criteria and Severin radiographic classification. The paired sample t test was used to compare the Bony Acetabular Index, the Center-Edge Angle and the Reimers Index of preoperative, 1 years after operation and the last follow-up. Results All cases were followed up for (12.10±1.02) years. Compared with preoperative parameters, 1 year after operation and the last follow-up, the Bony Acetabular Index recovered from (37.76±10.65)° to (5.04±3.76)°to (8.71±3.42)°, and the Center-Edge Angle recovered from (-55.61±43.29)° to (40.18±8.73)°to (33.58±8.75)°, and the Reimers Index recovered from (73.14±28.11)% to (14.17±11.78)% to (14.17±11.78)%, the average value recovered to the normal range. There was significant difference between the Bony Acetabular Index, the Center-Edge Angle and the Reimers Index of 1 years after operation and the last follow-up, as compared with preoperative parameters(P<0.05). The Reimers Index was significantly different for patients in the 1 years after operation and the last follow-up (P<0.05). The good rate of hip function was 84.81% (67/79)according to the Mckay clinical criteria to assess hip function, and the good rate of imageology was 75.95%(60/79) according to Severin radiographic classification in the last follow-up. Pearson contingency coefficient correlation analysis showed that main risk factors for Mckay clinical criteria seem to be unilateral/bilateral hip, AVN and recurrent subluxation(contingency coefficient =0.359、0.599、0.649, P<0.05); and the main risk factors for Severin radiographic classification were age, AVN and recurrent subluxation(contingency coefficient =0.356、0.478、0.707, P<0.05). In the last follow-up, 6 hips (7.59%) had recurrent subluxation after at a mean of 2.21 years after the initial open reduction. Pearson contingency coefficient correlation analysis showed that main risk factors for recurrent subluxation seem to be age, unilateral/bilateral hip, Tonnis classification and AVN (contingency coefficient =0.254、0.289、0.274、0.319, P<0.05). Conclusions Open reduction, proximal femur osteotomy and Pemberton’s pericapsular osteotomy are safe and effective procedures for the surgical treatment of DDH in infancy and childhood. Age, Tonnis classification, bilateral hip dysplasia and AVN are main risk factors for recurrent subluxation of DDH. Key words: Hip dysplasia; Osteotomy; Postoperative complications