Midterm results after subtrochanteric end-to-side valgization osteotomy in severe infantile coxa vara.

BACKGROUND For the treatment of the severe infantile coxa vara it is mandatory for the orthopaedic surgeon to observe the mechanobiology of the growing hip before and after the surgical intervention. We hereby would like to present our experiences with the subtrochanteric end-to-side valgization osteotomy and to compare the procedure with the alternatively used Y-shaped osteotomy as described by Pauwels. METHODS Thirteen patients (20 hips) who had undergone subtrochanteric end-to-side valgization were followed for a mean 6.2 years (range, 0.8 to 12.8 y). At the time of surgery the mean age was 7.1 years (range, 2.0 to 13.3 y), last follow-up examination was performed at a mean of 13.4 years of age (range, 5.1 to 18.3 y). The deformities were etiologically based on 5 entities: congenital coxa vara (n=1), osteochondrodysplasias (n=12), postosteomyelitic coxa vara (n=5), and avascular femoral head necrosis in the course of congenital dysplasia of the hip (n=2). The follow-up rate was 100%.In addition, we analyzed a total of 93 pelvic radiographies with a total of 139 hip joints. Thirty angles and distances were assessed according to parameters described in the literature. RESULTS Although preoperatively 12 patients presented with a positive Trendelenburg's sign, it was only present postoperatively in 2 patients. Duchenne's limp reduced from 10 to 1. All of the 15 preoperatively apparent nonunions could be healed by means of surgery. Two hips redeveloped pathologically lowered collodiaphyseal angles postoperatively, one of which had to undergo revision surgery. Preoperatively 15 out of 20 patients (75%) showed nonunions all of which healed after surgery. No recurrence could be seen at the time of the last follow-up.The following angles were assessed on plain radiographies of the pelvis preoperatively and directly postoperatively as well as on the last follow-up at a mean of 85 months: CCD-angle 98 degrees/156 degrees/144 degrees, EY-angle 55 degrees/5 degrees/15.7 degrees, AY-angle 32 degrees/75 degrees/66 degrees, CE-angle 20 degrees/25 degrees/18 degrees, AC-angle 20 degrees/18 degrees/20 degrees. The articulotrochanteric distance was 5 mm/26 mm/14 mm. CONCLUSIONS The subtrochanteric end-to-side valgization osteotomy showed to be highly effective in the management of the infantile coxa vara, improving the clinical impairment of the patients postoperatively. All of the preoperatively present nonunions showed osseous consolidation at follow-up examination. Only minor revarization tendencies could be found. The procedure is technically less demanding, safer and more efficient regarding the lengthening of the affected limb in comparison to the Y-shaped intertrochanteric osteotomy as described by Pauwels. LEVEL OF EVIDENCE Case-control study (EBM-level III).