Prognosis and complications with proximal femoral fractures
1. General considerations
Capital physeal fractures, femoral neck fractures, and comminuted proximal femoral fractures have a good prognosis.
The prognosis for capital physeal and femoral neck fractures is affected by the age of the patient at the time of the trauma, and growing potential of the animal.
The most common complications in proximal femoral fractures are:
Premature closure of the physis
Malalignment with malunion
Femoral neck resorption “apple coring”
2. Premature closure of the physis
Premature closure of the physis occurs due to the initial trauma. The consequences of this closure are directly related to the remaining growing potential of the physis. The growth plate normally closes at about 6-8 months of age. Younger affected patients therefore have a more guarded prognosis.
Premature closure of the physis can be associated with limb shortening.
3. Malalignment with malunion
Malalignment is a common complication associated with a multifragmentary proximal femoral fracture repair. Rotational malalignment in comminuted fractures can occur due to a lack of recognizable landmarks that would aid the surgeon to properly align the limb.
Limb alignment can be assessed by clinical evaluation and intraoperative fluoroscopy or radiographs.
Incorrect reduction during fracture treatment leads to an increased stress on the implant and may result on collapse of the fixation.
4. Secondary Osteoarthritis
Secondary osteoarthritis is a common complication of articular fractures. The initial trauma, surgical trauma, positioning of intra-articular implants, and premature closure of the growth plate may lead to this complication.
5. Implant failure
Case example of a 2 year old male castrated ragdoll cat that acutely became lame in both pelvic limbs in the house with no evidence of trauma.
Preoperative films show bilateral physeal fractures at the femoral heads. Diagnosis is capital physeal dysplasia due to age of the cat at time of diagnosis.
Surgical fixation with 3, 0.035inch K- wires.
Note the right side the pins are barely engaging the physis.
Left side the repair is adequate.
Two weeks later there is loss of reduction on the right capital physis from pin migration. This highlights the importance of making sure the pins engage sufficient bone in a small, thin physis.
Incorrect implant selection, insufficient fracture reduction, and/or insufficient bone purchase in the proximal fragment (or in the femoral head in cases of Salter Harris type I fractures) may lead to this complication.
6. Sciatic neurapraxia
Sciatic neurapraxia is most often associated with the retrograde insertion of an intramedullary pin or with proximal intramedullary pin migration.
If retrograde pin insertion is used, the leg should be held in adduction and slight extension while the pin is inserted to avoid sciatic nerve injury. After placement, the intramedullary pin should be cut short, at (or below) the level of the trochanter, so it does not interfere with the sciatic nerve.
Aggressive soft tissue retraction during fracture reduction may also lead to this complication.
7. Femoral neck resorption
Resorption of the femoral neck is frequently observed following repair of femoral neck fractures or Salter-Harris fractures of the femoral head in immature animals. This resorption is likely caused by vascular damage to the blood supply of the femoral head and neck. This resorption is generally self-limiting and may not cause a clinical problem. As a precaution, a slow return to normal activity is recommended.