NON-UNION

s 1 year down the line following an open fracture of the tibia treated with an intramedullary nail.

1.  Describe the radiograph and explain the diagnosis.

 This is a lateral radiograph showing a tibial shaft fracture treated with an intramedullary nail. The nail is backing out and the proximal screw is clearly broken. The fracture shows no evidence of healing 12 months post-surgery and therefore this would be described as a non-union.

  Treatment with a reamed intramedullary nail for closed fractures has a reported rate of non-union of between 1% and 4%. Following grade 1 open fractures, the rate of non-union remains low, at 2%, but it increases up to 36% for Gustilo and Anderson grade IIIB injuries.

2.  What is the definition of a non-union?

 A non-union is described as a failure of a fracture to heal within the time frame expected for that specific fracture. The U.S. Food and Drug Administration (FDA) defined non-union as a failure for a fracture to unite by 9 months, with no radiographic progression towards union in the previous 3 months.

3.  What are the clinical findings in a non-union?

 Clinically, patients may have ongoing pain at the fracture site and, in the lower limb, pain on weight bearing is a classical symptom of non-union. On examination, there may be pain on palpation in addition to movement and crepitus at the fracture site.

  In an infected non-union, patients may describe wound problems after surgery such as infected or leaking wounds and may have required antibiotics in the post operative phase. There may be ongoing inflammation at the fracture site in the form of erythema and persistent/night pain may be present, in addition to constitutional symptoms of infection such as sweats, fever, rigors, weight loss and loss of appetite.

4.  What is the difference between clinical and radiographic union?

 Clinical union is defined as the absence of tenderness or motion at the fracture site with no pain on loading. Radiographic union is defined as the presence of visible bridging trabeculae on three out of four cortices on orthogonal radiographs.

5.  What are the causes of non-union?

 Factors causing non-union can be divided into patient factors, fracture factors or surgical factors.

Patient factors:

•      Age (paediatric fractures heal quicker than adult fractures)

•      Smoking and excess alcohol

•      Drugs (NSAIDs, corticosteroids)

•      Medical co-morbidities (diabetes, peripheral vascular disease, malnutrition, anaemia, hypothyroidism, hyperparathyroidism) Fracture factors:

•      Bone involved (femoral shaft take 16 –/+ 4 weeks to unite, whereas a distal radius fracture may heal in under half this time)

•      Area of bone involved (diaphyseal fractures generally take longer to heal than metaphyseal fractures). Classically, the distal tibia and proximal pole of the scaphoid are at high risk of non-union

•      Fracture type (high-energy fractures, open fractures, comminuted fractures, bone loss, and fractures associated with significant soft tissue damage or periosteal stripping will take longer to heal) • Infection

Surgical factors:

•      Extensive soft tissue damage/periosteal stripping

•      Inadequate stability

•      Rigid fixation with gapping at the fracture site

•      Introduction of infection

6.  Do you know of any different types of non-union?

      Non-unions can be described as being either hypertrophic or atrophic:

Hypertrophic non-unions are a mechanical problem. They occur when there is a good blood supply but excessive strain at the fracture site prevents progression of the callus to form bone.

Atrophic non-unions are a biological problem. Almost all the patient, fracture, and surgeon factors already discussed can lead to an atrophic non-union. A fracture fixed with rigid fixation but with the fracture fragments distracted will also lack stimulation of callus formation.