Fracture non-union in the dog: causes and treatment
3-year-old Greyhound operated on 16 weeks ago for a radial fracture with an external fixator. It is still lame; serial radiographs show no progress: rounded, sclerotic ends, sealed medullary canal, no callus and a loose fixator pin.
Which diagnosis and approach are correct?
chevron_right Show answer and explanation
A. Non-viable non-union due to instability: new stable fixation, freshen the ends by opening the medullary canal and autologous cancellous bone graft
Correct. With no callus and sealed ends, the fracture has stopped trying to heal. It needs two things: stability (the loose pin shows it was lacking) and biological stimulus (cancellous graft provides osteogenic cells and factors).
B. Delayed union: keep the fixator for 8 more weeks without changes
In delayed union healing progresses, albeit slowly, between radiographs. Here there is no progress and the canal is sealed: waiting will not solve it.
C. Hypertrophic non-union: a bone graft is enough, without changing fixation
A hypertrophic (elephant's foot) non-union has abundant callus and is biologically active; what it lacks is stability. This case has no callus, and grafting without stabilising is doomed to fail.
D. Remove the fixator and apply a splint, since the implant is causing the lack of union
The cause is not the implant but the instability. A splint provides even less stability and, in the radius, perpetuates the non-union.
lightbulb Key takeaway
The most common cause of non-union is instability, followed by poor blood supply, infection and a large fracture gap. Viable non-unions mainly need stability; non-viable ones need stability plus biological stimulus.
Test yourself with 10 random questions
Musculoskeletal system · 100 questions, a different test every time
Related questions
Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.