Canine Elbow Realignment Osteotomy (CERO): Validation of the Accuracy of Acute Radial Lengthening in a Cadaveric Incongruency Model

Objective: To verify the ability of a novel Canine Elbow Realignment Osteotomy (CERO) system for acute axial radial or ulnar lengthening to restore normal elbow congruency in a shortened radius cadaver model using assessment by computed tomography (CT). Study Design: In vitro cadaver study. Animals: Five pairs of greyhound forelimbs from animals euthanatized for reasons unrelated to the study. Methods: CT of each elbow was performed (1) pre-operatively (pre-op), (2) after placement of a linear motor IMEX™ external skeletal fixator (ESF) on the radius with diaphyseal ostectomy and radial shorting of 1–5 mm (post-ESF), and (3) after CERO surgery to lengthen the radius proximal to the ostectomy site by an amount equal to the degree of radial shortening (post-CERO). The joint space at 7 loci on dorsal plane and 6 loci on sagittal plane reconstructions was measured to assess changes in joint congruity between pre-op, post-ESF, and post-CERO. Repeated measures ANOVA with post hoc comparisons were performed to compare measurements between the 3 groups. Results: Mean joint space measurements at most loci in the dorsal and sagittal planes were significantly different post-ESF compared with pre-op, confirming development of joint incongruency with the model. Post-CERO joint space measurements did not differ significantly compared with pre-op measurements, demonstrating the return to normal joint congruency using the CERO procedure. Conclusion: CERO surgery restored humeroradioulnar congruency in our cadaver model and may have application for acute correction of axial radial or ulnar incongruency in canine elbows secondary to elbow dysplasia or premature growth plate closure.