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