Causes of Nonunion

Biologic causes of nonunion

LOCAL -Excessive  soft-tissue  stripping  (from  injury  or by surgeon)
-Bone loss
-Vascular injury
-Chronic diseases
-Diabetes mellitus
-Chronic anemia
-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
-Technical error(s)

Types of Nonunion

Nonunions 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 nonunion

It 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.