Objective: To evaluate long-term clinical outcomes of dogs surgically treated for proximal humeral osteochondrosis (OC).
Study design: Cross-sectional study.
Sample population: Twenty dogs (n = 26 shoulders).
Methods: Dogs treated with surgical debridement of proximal humeral OC lesions >12 months prior were enrolled. Orthopedic examination (including limb circumference and shoulder goniometry), kinetic gait analysis, shoulder radiographs, shoulder computed tomography (CT), and shoulder arthroscopy were performed. All owners completed a dog mobility questionnaire.
Results: Brachial circumference (P = .003) and maximum shoulder extension (P = .013) were decreased and maximum shoulder flexion (P = .008) was increased (ie less flexion) in the OC limb versus the contralateral limb in unilaterally affected dogs. There were no differences in peak vertical force and vertical impulse between affected and unaffected limbs. Dogs demonstrated a 4.4% decrease in load distributed to the operated limb. Osteoarthritis was present in all shoulders treated for OC lesions. The degree of osteoarthritis in OC-affected shoulders was increased compared to the contralateral limb as evaluated on CT (P = .005) and radiography (P = .0001) in unilaterally affected cases. Moderate-to-severe synovitis was seen in all OC-affected joints. Arthroscopically, all lesions were noted to have patchy, incomplete cartilaginous infilling. Median of aggregate Liverpool Osteoarthritis in Dogs (LOAD) scores was 6.
Conclusion: All dogs exhibited ipsilateral muscle atrophy and progressive osteoarthritis, with most dogs exhibiting subtle lameness on the subjective gait examination. Despite this, owner-perceived mobility was satisfactory.
Clinical significance: Progression of joint disease over time should be expected; however, the abnormalities detected on examination appear to be of questionable clinical relevance.