Many factors may impede bone healing causing delayed union or non-union. They are conveniently discussed in terms of the injury, the bone, management of the injury and the patient, although in any one case, all may contribute.
The injury:
- interposition of tissue between the bone fragments - periosteum, muscle or cartilage
- expulsion of the bone fragment at the scene of the injury producing an excessive gap
- severe comminution or displacement producing instability
- intact fellow bone preventing realignment and bony apposition - e.g. an intact fibula with fractured tibia
- soft tissue contracture producing a deforming forces - e.g. ankle equinus causing angulation of a mid-tibial fracture
The bone:
- poor quality - e.g. a pathological fracture
- poor local circulation e.g. fractured neck of femur
- infection
Management of the fracture:
- excessive traction - pulling the fragments too far apart
- poor fixation - poorly applied or incorrect technique
- excessive splintage - bone becomes osteoporotic, muscles atrophied, and joints stiff
The patient:
- poorly motivated - doesn't want to mobilise
- poorly nourished
- poor general health