THE EFFECT OF TRIPLE PELVIC OSTEOTOMY ON HIP FORCE IN DYSPLASTIC DOGS- A THEORETICAL-ANALYSIS

The effect of a triple pelvic osteotomy (TPO) procedure on the forces acting about the hip joint was examined in five dysplastic canine hips using a previously described theoretical analysis. Hip reaction force (F-h) and its angle of application (Theta(h)) were calculated from ra diographic measurements made before and after TPO procedures which seq uentially increased acetabular ventroversion from O degrees to 20 degr ees, 30 degrees, and 40 degrees. The results of the in vitro study sho wed that F-h decreased with increasing acetabular ventroversion reachi ng an asymptotic value between 30 degrees and 40 degrees. The decrease in F-h corresponded to an increase in Theta(h) toward the vertical, w ith statistical significance found in both F-h and Theta(h) between 0 degrees and 20 degrees. The changes observed in F-h and Theta(h), afte r TPO were attributed to the medialization of the femoral head resulti ng from the reduction of the subluxated head. The results of this stud y suggest that the noted reduction in the magnitude of the forces acti ng on the hip joint may act in concert with increased coverage of the femoral head to effect the beneficial clinical results observed with t he TPO procedure. (C) Copyright 1996 by The American College of Veteri nary Surgeons