E5315. Fracture Nonunion and Malunion: What the Orthopedic Surgeon Wants to Know
  1. Joseph Burns; University of California
  2. Arash Anavim; University of California
  3. Lawrence Wang; University of California
  4. Maryam Golshan; University of California
  5. Peter Pham; University of California
  6. Anderanik Tomasian; University of California
Fracture nonunion can result in considerable patient morbidity. Nonunion has been reported in approximately 5–10% of fractures in adults of the younger to middle age groups, with peak incidence of approximately 35–44 years of age. There have been reports rising incidence of nonunion, thought related to increased probability of patient survival in major traumas. The purpose or this presentation is to describe mechanisms of bone healing and relation to failure of repair, the related and relevant imaging findings, and current treatments options and appearances.

Educational Goals / Teaching Points
There is no current universally accepted definition of fracture nonunion in the orthopedic surgery community. However, the U.S. FDA does nonunion fracture as a persistent fracture at least 9 months after initial injury, with no radiologic signs of healing for the final 3 months. A variant form of this, delayed union will also be briefly discussed. The varying forms of fracture nonunion will be presented, with discussion of the various imaging characteristics of each. These include atrophic nonunion, where opposing bony surfaces are partially resorbed, without evidence of callus formation, oligitrophic nonunion, where there if no or minor callus formation, and hypertrophic nonunion, where there is exuberant callus formation, but without bony bridging. The variants of pseudoarthrosis and infected nonunion will also be discussed. Treatment of the varying types, including rigid stabilization of hypertrophic nonunion, augmentation for atrophic type nonunion, bone grafting, biologic stimulation and osteogenesis, and bone transport with ring external fixator as well as with bone transport intramedullary nail will also be discussed. Review of treatment failure and the imaging appearance will also be included.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The goal is to delineate the physiological mechanisms of bone healing and their correlation with the imaging appearances on different modalities at different stages in the altered healing process. Possible mechanisms and imaging appearances of delayed/failed repair will be reviewed, including radiographic evaluation, CT, and MRI. Traditionally, radiography has been the first line in evaluation of nonunion and delayed union, and still plays a vital role. CT has more recently emerged as an accurate method for evaluation the opposing bone surface integrity and geometry. Finally, dynamic contrast-enhanced MRI is emerging as a popular method for assessment. Appearances of the posttreatment facture will be reviewed.

Fracture nonunion is increasing in prevalence due to increasing survival of major trauma incidents. This educational presentation will review the various types of fracture nonunion and delayed union with their imaging appearance and appearance under treatment.