Causes of Nonunion
Biologic causes of nonunion
|LOCAL||-Excessive soft-tissue stripping (from injury or by surgeon)
-Metabolic/endocrine abnormalities (e.g.vitamin D deficiency)
-Medications (steroids, NSAIDs, antiepileptics)
Mechanical causes of nonunion
|Inappropriate stabilization||-Too little or insufficient fixation|
-Too much or too rigid fixation
-Inappropriate implant choice
-Inappropriate implant position
Types of NonunionNonunions can be classified as:
- based on location:
- based on presence or absence of infection:
- based on etiology:
- Pseudoarthrosis i.e. formation of false joint at the site of nonunion.
Diagnosis/Workup of nonunionIt includes history, physical examination, radiographic examination, & laboratory evaluation.
- History– detail history of previous treatment & its timeframe; any documented infection; signs/symptoms of current or previous infection; presence/absence of pain.
- Physical examination–
-a detailed neurovascular examination
-assessment for presence/absence of tenderness at the fracture site,
-deformity, malrotation, leg-length discrepancy, joint range of motion, compensatory contractures,
-erythema, & drainage.
- Radiological examination/Imaging:
Goals of imaging: include assessing union, monitoring progression toward union, determining etiology for delayed union/nonunion, evaluating integrity of implants, & checking for signs of infection.
Plain X-ray film– the cornerstone for evaluation of fracture healing; all 4 views should be taken; used to evaluate formation of callus & progression of union.
CT Scan– highly sensitive for nonunion but lacks specificity, & limited use due to hardware artifact in case of implant.
MRI– used in certain situations.
Nuclear imaging– not used regularly.
- Laboratory investigations:
-CBC including white cell count
-ESR & CRP
While using CBC, ESR, CRP to assess infection, the positive predictive value(PPV) when all 3 values are positive is 100%
-25-hydroxy vitamin D
– Other investigations as per case.