EXPRESS: Radiographic findings of the femora and tibiae in cats affected by patella fracture and dental anomaly syndrome

OBJECTIVES: The objective of the study was to describe radiographic skeletal changes in cats affected by patella fracture and dental anomaly syndrome (PADS), with particular focus on the femora and tibiae including bone density alterations, evidence of stress fractures and femoral morphology. METHODS: Cats were retrospectively selected from a database of PADS affected cats. Radiographs were independently evaluated by five veterinary radiologists and three orthopaedic surgeons for cortical thickening, medullary opacity changes, the presence of osteopetrosis, degenerative joint disease and additional fractures and subjective assessment of the femoral shape. RESULTS: One hundred and twenty‑six cats met the inclusion criteria. All had patellar fractures and 22.2% (n=28) had additional fractures, most commonly involving the proximal tibia in 13.5% of cases (n=17), proximal fibula in 11.9% of cases (n=15) and pelvis. Four cats showed an incomplete radiolucent line in the cranioproximal tibia with surrounding sclerosis, consistent with developing stress fractures. Medullary opacity changes in the femora and/or tibiae were present in 8.7% (11/126) of cats, more often patchy than diffuse in appearance. In 4.0% of cases (n=5), a generalised increase in bone opacity compatible with osteopetrosis was identified. Femoral shape was assessed in 74 cats, with 35% (n=26) having a normal morphology, and 9.5% (n=7) and 2.7% (n=2) having a stovepipe or champagne-fluted morphology respectively. Consensus was not reached in 52.7% (n=39) cases. CONCLUSIONS AND RELEVANCE: Most PADS‑affected femora and tibiae appeared radiographically normal, however, a subset of cats demonstrated radiographic features of osteopetrosis, altered femoral morphology and proximal tibial fissure lines suggestive of early stress fractures. These findings suggest that specific structural and morphological changes in the long bones may be present, or predispose, cats to the insufficiency fractures characteristic of PADS and emphasise the importance of clinicians recognising these subtle radiographic features to aid earlier diagnosis and appropriate case management.