Nonunions

The "Diamond Model" (or Diamond Concept) of bone healing is a theoretical framework in orthopedic surgery and regenerative medicine that outlines five interdependent factors needed for successful fracture repair and non-union treatment:

Osteogenic cells, Osteoinductive mediators, Osteoconductive scaffold, Mechanical stability, and adequate Vascularity. The first four are connected by vascularity - without blood flow no healing can occur.

When evaluating a nonunion, this framework gives us a checklist upon which to determine the cause of the nonunion. A failure in any of the pillars of the model will result in a failed fusion or fracture to heal. 

Some conditions present specific challenges to bone healing that are not obvious. For example, obesity is widely known as a risk factor for nonunion. But it is not enough to just categorize high BMI solely; the obese individual poses challenges due to mechanical stability being inadequate, chronic inflammation where adipose tissue releases pro-inflammatory cytokines creating an environment favoring osteoclastic activity, and metabolic abnormalities such as insulin resistance and vitamin D deficiency.

For me the key to a successful outcome of surgery or conservative treatment of fractures is mitigating risk factors when possible, or circumventing them altogether. However when faced with a nonunion, the surgeon has to answer the two questions - how can I improve mechanics around the nonunion site and how can I improve the tissue/organ/whole body biology? Without answering these the nonunion will likely persist leading to even further morbidity.

The content of this podcast is for educational and informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.