Surgical repair of spine instability in dogs and cats

Abstract

CASE HISTORY: The medical records of a veterinary hospital in Italy were reviewed retrospectively for cases of dogs and cats diagnosed with vertebral instability (VI) and treated surgically using a bone plate, screws with bushings, and polymethylmethacrylate (PMMA) that had ≥ 4 weeks' follow-up data. Dogs were a median of 16.15 (min 2.7, max 32) kg and 90 (min 38, max 142) months old, and cats were a median of 4.05 (min 2.7, max 5) kg and 33 (min 5, max 61) months old. The aetiology of VI was primarily traumatic in eight cases (road traffic accidents, n = 6; fall from height, n = 1; bite injury, n = 1) and degenerative in two cases (C1-C2 luxation, n = 1; and lumbosacral instability, n = 1). CLINICAL FINDINGS: Neurological examinations were performed pre- and post-operatively using the modified Frankel scale. Neurological grades prior to surgery were grade 0 (n = 1), grade 1 (n = 2), grade 3b (n = 6), and grade 5 (n = 1). Diagnostic imaging (CT and radiography) was conducted to classify fractures/luxations, plan surgical interventions and evaluate post-operative progress. VI was localised to the lumbar (n = 2), lumbosacral (n = 1), or thoracic (n = 1) spinal segments of cats and the cervical (n = 1), thoracolumbar junction (n = 1), lumbar (n = 2), or lumbosacral (n = 2) spinal segments of dogs. TREATMENT AND OUTCOME: All animals were treated surgically with a bone plate, screws with bushings and PMMA for stabilisation, as unilateral constructs (three cats, two dogs) or bilateral constructs (one cat, four dogs). A minor complication (Kirschner wire breakage) occurred in one dog, and a major complication (cement rupture) occurred in one cat; both resolved without surgical intervention and did not compromise stability or cause neurological deterioration.Post-operative neurological assessment revealed improvement in 9/10 cases, with two cases improving by one neurological grade, and seven cases improving by two grades. At the 4-week follow-up assessment, seven cases maintained their discharge status, while three improved by one additional grade at the 16-week follow-up assessment. CONCLUSIONS AND CLINICAL RELEVANCE: This case series suggests that VI stabilisation with a bone plate, screws with bushings, and PMMA is a viable method producing satisfactory outcomes. Increased exposure surface at the screw/bushing/PMMA interface may increase the strength of the fixation. UNLABELLED: K-wire: Kirschner wire; PMMA: Polymethylmethacrylate; VI: Vertebral instability.