Fragmented fabella on radiographs: cause of the lameness?
5-year-old Rottweiler, 45 kg, with a 4-week left hind limb lameness. On the lateral stifle radiograph the lateral fabella appears divided into two fragments with rounded, smooth edges; there is also joint effusion. The fabella of the right stifle has a similar appearance.
What is the most appropriate next step?
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A. Consider the bipartite fabella a probable incidental finding and assess stifle stability (cranial drawer, tibial compression) under sedation if needed
Correct. Smooth edges and a symmetrical appearance in the other stifle suggest a congenital multipartite fabella, not a fracture. Effusion in a large dog points to cruciate rupture, which is far more common.
B. Lateral fabellectomy, because the fabella fracture explains the lameness
Symptomatic fabella fracture is rare and usually has sharp, irregular edges. Operating on the fabella without ruling out cruciate rupture would leave the likely cause untreated.
C. Osteosynthesis of the fabella with a lag screw
The fabella is too small to fix, and even with a genuine fracture it is managed conservatively or excised if pain persists.
D. Immobilise the stifle in a splint for 6 weeks so that the fabella heals
A bipartite fabella is not a fracture and will not unite. Prolonged stifle immobilisation causes stiffness and atrophy.
lightbulb Key takeaway
When a radiographic finding is doubtful, compare with the contralateral limb. Bipartite or displaced fabellae are usually incidental; attribute lameness to the fabella only after ruling out common causes, above all cruciate rupture.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.