Evaluation of ilial screw loosening after triple pelvic osteotomy in dogs: 227 cases (1991-1999).
OBJECTIVE
To investigate factors influencing screw loosening after triple pelvic osteotomy (TPO) and ischial wire stabilization of the acetabular segment.


METHODS
Retrospective case series. Animals-227 dogs with congenital hip dysplasia or subluxated hip joints.


METHODS
Medical records and radiographs of 227 dogs that underwent 332 TPO procedures were evaluated, and data pertaining to screw type, plate position, sacral screw engagement, use of ischial interfragmentary wires, and pelvic alignment were assessed for associations with screw loosening.


RESULTS
Complications developed in 96 of the 332 (29%) procedures. Cancellous screws without sacral engagement were associated with the lowest frequency (6%) of loosening, compared with cancellous and cortical screws engaging the sacrum and cortical screws that did not engage the sacrum. Frequency of screw loosening increased when cortical or cancellous screws engaged the sacrum and when cortical screws were used. In dogs that had surgery bilaterally, the first limb on which TPO was performed had a higher frequency of screw loosening than the second limb. Pelvic alignment loss was greatest (5.4 degrees ) when the 3 most cranial screws were loosened. Loss of pelvic alignment was significantly different between dogs that underwent surgery and had complications and those that underwent surgery and did not have complications in association with loosening of 1, 2, and 3 screws.


CONCLUSIONS
TPO screw loosening was multifactorial and related to stability of the affected ilium, screw type, and screw position. Placing cancellous screws that do not engage the sacrum in pelvic osteotomy plate positions 1 through 3 may decrease the number of screws that loosen.
Doornink
Michael T
MT
Department of Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA.
Nieves
Mary A
MA
Evans
Richard
R
D000818:Animals; D001863:Bone Screws / Q000009:adverse effects / Q000662:veterinary*; D004285:Dogs; D004868:Equipment Failure; D005260:Female; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000379:methods / Q000662:veterinary*; D006619:Hip Dysplasia, Canine / Q000601:surgery*; D008297:Male; D010027:Osteotomy / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D010384:Pelvic Bones / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology / Q000662:veterinary; D012189:Retrospective Studies; D016896:Treatment Outcome