Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Nonunion of Fractures

Basics
Description
  • Presence of a postfracture defect in a long bone beyond a reasonable expected healing date, or if no radiographic progression of healing is noted
  • If internal fixation is used to stabilize a fracture, a race exists between fracture healing and hardware failure.
  • Children, because of their active healing potential, rarely develop a nonunion unless other predisposing conditions are present.
  • Classification:
    • Atrophic nonunion:
      • Often poor blood supply
      • When visualized on radiographs, often show poor bone quality with tapered edges
      • Often occur in osteoporotic bone
    • Hypertrophic nonunions:
      • Good blood supply
      • Most go on to heal if adequate stabilization can be achieved.
Epidemiology
Incidence
  • The incidence depends on the fracture type.
    • 13% of tibial fractures
    • 4-11% of clavicle fractures, depending on location
    • Tibial shaft, femoral neck, and scaphoid fractures are at high risk for nonunion because they have a more tenuous blood supply than other bones, which often is damaged with the injury.
Risk Factors
  • Poor nutritional status
  • Poor bone quantity and quality
  • Suppressed immune system
  • Presence of bone infection may contribute to development of a nonunion.
  • Smoking
  • Poor soft-tissue envelope
  • Vascular compromise
  • NSAID use
  • Open fractures
  • Poor fracture reduction
  • Distal tibia fractures
Etiology
  • Injury-related causes include segmental bone loss, extensive soft-tissue damage, and loss of adequate blood supply.
  • Treatment-related factors include quality of reduction, amount of distraction, and length of immobilization.
  • Inadequate fracture stabilization is a common cause of fracture nonunion.
Diagnosis
Signs and Symptoms
History
  • Patients have a history of a fracture that continues to be painful.
  • The patient may have broken hardware.
  • Pain often occurs after use of the limb.
Physical Exam
  • Patients have continued tenderness at the fracture site.
  • Motion of the bony fragments may or may not be evident.
Tests
Imaging
  • Radiography:
    • Plain AP and lateral radiographs, to determine the presence of callus formation
    • Serial radiographs, to ensure callus progression
  • CT:
    • Excellent at revealing nonunion
    • In many fractures, the fracture plane is difficult to see on plain radiographs because of overlap of the bone fragments.
  • Bone scans, to help determine whether increased blood flow and subsequently increased bone turnover is present at the fracture site
  • MRI is useful when hardware is not present.
Pathological Findings
  • Thick fibrous tissue with areas of uncalcified callus formation
  • A synovial pseudarthrosis or false joint may develop with excessive motion.
Differential Diagnosis
  • Delayed union, characterized by some tenderness and motion at the fracture site with variable amounts of callus present after a period in which most fractures would be healed clinically
  • Painful hardware
  • Posttraumatic arthritis
Treatment
General Measures
  • Most nonunions are treated with surgical intervention.
  • Aggressive treatment of delayed union can help prevent nonunion and hardware breakage.
  • Nonoperative interventions:
    • Bone stimulators (electrical or ultrasound)
    • Smoking cessation
    • Discontinuation of NSAIDs
    • Use of weightbearing casts or functional braces
Surgery
  • Surgical treatment of nonunions is determined by type of host, soft-tissue coverage, precise location of the nonunion, type of nonunion, and previous fracture treatment.
  • Patients with severe medical compromise, poor soft-tissue coverage, or poor vascular supply may be candidates for amputation.
  • Hypertrophic nonunion should be treated with rigid fixation of the nonunion, which may require revision of the internal fixation.
  • Nonunion of long-bone fractures with intramedullary nails may be treated with nail dynamization or exchange nailing.
    • Reaming the canal provides local bone graft and allows for placement of a larger diameter nail.
  • Bypass or wave plating allows for fixation and bone grafting (7).
  • For tibial nonunions, bracing may be combined with fibular osteotomy.
  • Well-stabilized atrophic nonunions are treated with bone grafting.
    • Bone graft may be autograft, allograft, or synthetic.
    • The fracture nonunion should be exposed and curetted, and the bone ends should be burred back to bleeding, viable bone.
    • Bone graft material then is packed into the nonunion.
    • The use of bone morphogenic protein 2 recently has been approved for tibial nonunion treatment.
    • The optimal bone graft material or bone morphogenic protein is unknown.
      • Factors to consider with the use of autograft include the need for a 2nd incision and the relative quality of the patient’s bone.
      • Some patients may not want to have a 2nd incision with its risk of pain or infection.
  • Femoral neck nonunions may be treated with realignment osteotomy or joint replacement.
  • Infected nonunion:
    • Treatment is challenging and requires debridement of the infection, fracture stabilization, removal of dead space, and soft-tissue coverage.
    • Plastic surgery reconstruction may be necessary, and multiple surgeries often are necessary.
  • Large bone defects may be managed with bone transport via an external fixation and the Ilizarov method.
Follow-up
Prognosis
  • 90% of nonunions are treated successfully with 1 surgery.
  • In 80% of nonunions, limb length and alignment are restored.
  • If infection is present, often >1 surgery is required.
Complications
  • Infection and osteomyelitis
  • Hardware failure
  • Continued nonunion
  • Pain
  • Malunion
  • Joint stiffness
  • Pain and infection at the bone graft donor site
Patient Monitoring
Serial radiographs are obtained once a month, to assess the development of callus.
 
Miscellaneous
Codes
ICD9-CM
733.82 Nonunion fracture
 
Patient Teaching
Strict adherence to the recommendations of the orthopaedic surgeon regarding activity and care of the fracture may reduce the likelihood of developing a nonunion, particularly with problematic fractures.
 
Prevention
Excellent reduction of fractures, smoking cessation, and aggressive treatment of delayed unions decrease nonunion rates.
 
FAQ
Q: How long does a nonunion take to heal?
A: 90% of nonunions are treated successfully with 1 surgical intervention, and healing occurs over a 3-4-month period. Full rehabilitation with muscle strengthening takes longer, because the patient often is debilitated before treatment.

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