Objective—To quantify bone mineral density (BMD) in the medial coronoid process (MCP) of dogs with and without fragmented medial coronoid processes (FMCPs) by use of dualenergy x-ray absorptiometry.
Sample Population—50 osteochondral samples from 31 dogs that underwent subtotal coronoid ostectomy for unilateral or bilateral FMCP and 10 control osteochondral samples of the MCP collected from forelimbs of 5 cadaveric Greyhounds.
Procedures—Each sample was mounted in proximodistal and mediolateral orientations for BMD determinations via dual-energy x-ray absorptiometry, and area-of-interest data (0.03-cm2 increments) were obtained. Values of BMD were compared between left and right limb control samples, between control and FMCP samples, and between axial and abaxial regions of the control or FMCP samples.
Results—The BMD in control and FMCP samples in both proximodistal and mediolateral orientations differed significantly. Mean BMD throughout the MCP was decreased in FMCP samples, compared with control sample findings. In both control and FMCP samples, BMD of the abaxial half of the MCP was 50% higher than that of the axial portion.
Conclusions and Clinical Relevance—The similar pattern of BMD in osteochondral samples of the MCP in dogs with and without FMCP indicated that the MCP was eccentrically loaded during weight bearing. Topographic variation in BMD in the MCP, and hence tolerance to compressive loading, suggested that the abaxial portion of the MCP in dogs was more resistant to compressive load than was the axial edge. This difference may predispose the coronoid process to microcrack formation and fragmentation at that juxtaposition.
A 6-month-old male Miniature Dachshund was referred for examination and correction of a unilateral pes varus deformity.
Clinical examination and diagnostic imaging revealed varus, procurvatum, and internal torsion of the distal aspect of the left tibia causing intermittent lameness.
TREATMENT AND OUTCOME
True spherical osteotomy performed with a dome-shaped saw allowed correction of the deformity in 3-D, and orthogonal internal plate fixation provided stabilization. No intraoperative or immediate postoperative complications developed. Outcome as judged by the clinician and the owners was satisfactory 2 weeks after surgery and excellent at each subsequent assessment. The patient remained free of clinical signs at the last follow-up 30 months after surgery.
To the authors’ knowledge, this case represented the first time a true spherical osteotomy was used to correct a pes varus deformity in a canine patient.