Veterinary Surgery 32:580-584, 2003 An Ex Vivo Mechanical Evaluation of Single Versus Double Semitubular Plate Fixation of a Transverse Distal-Third Scapular Osteotomy in the Dog JACQUELINE J. MAIR, DVM, STEPHEN M. BELKOFF, PhD, and RANDY J. BOUDRIEAU, DVM, Diplomate ACVS Objective—To compare single versus double semitubular plate fixation for scapular body fractures. Study Design—Ex vivo mechanical study. Sample Population—Eighteen paired cadaveric canine scapulae. Methods—Transverse scapular body osteotomies were created in the distal third of 18 pairs of scapulae. One scapula of each pair was repaired with a single plate, whereas the contralateral scapula was repaired with 2 plates. Initial strength and stiffness of the constructs were measured in 10 pairs of scapulae. Eight pairs of scapulae underwent cyclic loading and then were subjected to failure testing. Results—Double-plate fixation was significantly stronger (3,899  632 N) but not stiffer (614  130 N/mm) than the single-plate fixation (3,238  935 N and 537  202 N/mm, respectively). Cyclic loading variables were not significantly different between the 2 methods of fixation. After cyclic loading, double-plate fixation was significantly stronger (2,916  618 N) than single-plate fixation (2,347  495 N). There was no significant difference (P = .11) in stiffness between double- versus single-plate fixations: 734  247 N/mm and 595  139 N/mm, respectively. Conclusions—Double-plate fixation was generally stronger and stiffer than single-plate fixation. Because all constructs failed at loads that greatly exceeded those estimated to occur clinically, any difference between the 2 methods of fixation probably is not clinically relevant. Clinical Relevance—Single-plate fixation may be of sufficient strength for fixation of scapular body fractures. © Copyright 2003 by The American College of Veterinary Surgeons S CAPULAR BODY fractures are relatively uncom- mon in small animals. 1-8 One retrospective study reported a 2.4% incidence of scapular fractures over a 5-year period. 3 A variety of methods have been proposed to treat these fractures. There is a general consensus in the veterinary literature that fractures involving the scapular neck, glenoid cavity (an intra- articular fracture), and supraglenoid tuberosity require surgery, 1,2,4-6,8-10 but opinions about the treatment of scapular body fractures are more diverse and include surgical and nonoperative methods. 1-8,10 Most scapu- lar body fractures are treated nonoperatively using From the Department of Clinical Sciences, Tufts University School of Veterinary Medicine, North Grafton, MA, and the Biomechanical Instrumentation Laboratory, Department of Orthopaedic Surgery, Johns Hopkins University/Johns Hopkins Bayview Medical Center, Baltimore, MD. Supported by the Tufts University School of Veterinary Medicine Hill’s Resident Research Fund. Presented at the 30th Annual Conference of the Veterinary Orthopedic Society, Steamboat Springs, CO, February 28, 2003. Address reprint requests to Randy J. Boudrieau, DVM, Department of Clinical Sciences, Tufts University School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA 01536. Address correspondence to Stephen M. Belkoff, PhD, c/o Elaine P. Henze, Medical Editor, Department of Orthopaedic Surgery, Johns Hopkins Bayview Medical Center, 4940 Eastern Ave., A672, Baltimore, MD 21224-2780. © Copyright 2003 by The American College of Veterinary Surgeons 0161-3499/03/3206-0012$30.00/0 doi:10.1053/jvet.2003.50067 580