Review Question - QID 219202

This patient’s continued pain and radiographs are consistent with fracture nonunion. While he will likely require hardware removal and revision fixation surgery, the first step in management is to obtain basic serum labs to aid in determining the cause of his nonunion (Answer 1).

There are a variety of potential causes for fracture nonunion after undergoing operative fixation. These include biological, mechanical, patient-related, and injury factors, ultimately representing a multifactorial etiology for most non-union cases. In general, these nonunion cases are categorized and treated based on radiographic fracture site morphology in conjunction with serum lab values:

1. Hypertrophic Nonunion – fracture sites with abundant callous formation, however without primary cortical appositional remodeling. These are often caused by too much motion at the fracture site (i.e. inadequate fixation).
2. Oligotrophic/Atrophic Nonunion – fracture sites with minimal or no callous formation and thus no primary cortical appositional remodeling. These are often caused by lack of motion at the fracture site (i.e. excessively stiff fixation), nutritional deficiencies (i.e. low vitamin D), or lack of adequate blood supply to the area (i.e. avascular necrosis).
3. Septic Nonunion – fracture sites with variable callous formation but ultimately lacking primary cortical appositional remodeling. These are caused by infections at the fracture site.

In any case, an initial laboratory workup may provide information suggestive of the potential underlying etiology (i.e. infectious versus nutritional deficiency). The patient should be medically optimized for any endocrine abnormalities or nutritional deficiencies to ensure a successful revision surgery and ultimately fracture union.

Nauth and colleagues provided a review article on the principles of nonunion management. They discuss that all nonunion cases should undergo laboratory workup, as basic labs (WBC/CRP/ESR) serve as the best predictors for underlying infectious causation. Furthermore, they discuss that up to 20% of nonunion cases with normal inflammatory labs are found to have positive nonunion site cultures, placing them at risk for persistent infections and further revision surgeries. The authors conclude by discussing the main types of nonunion and available treatment options in the current orthopaedic trauma landscape.

Nino and colleagues provided a review article on the role of Vitamin D and its supplementation in orthopaedic trauma. They discuss that vitamin D insufficiency, broadly defined as serum 25-VitD3 lower than 20 ng/mL, has been shown to serve as a risk factor for elderly hip fracture, delayed fracture healing, and fracture nonunion. The authors note that while vitamin D deficiency is found in ~70% of nonunion cases, it is likely a contributing factor rather than the root cause of nonunion. The authors conclude that active assessment and management of vitamin D deficiency is low cost and low risk with significant potential benefit in the care of orthopedic patients.

Figure A demonstrates a highly comminuted subtrochanteric femur fracture with numerous lead pellets retained in the soft tissues. Figure B demonstrates this patient’s 9-month post-operative imaging revealing fracture nonunion and limited areas of callous formation. Illustration A demonstrates 6-week post-operative imaging after the patient underwent open nonunion takedown, allogenic bone grafting, and exchange nailing using a larger diameter nail. Illustration B demonstrates an intraoperative photograph during that revision surgery. The prior nail was found to have undergone fatigue failure and the 12-gauge shell wad was found embedded in the nonunion fracture site.

Incorrect Answers:
Answer 2: Providing a physical therapy referral and ordering a bone stimulator would be considered appropriate if laboratory evaluation rules out underlying infectious etiology. However, given this patient's history of a large open fracture site and erythema around the prior open wound, laboratory evaluation should be performed first.
Answer 3: Performing exchange nailing using a larger diameter intramedullary nail would be considered appropriate in the setting of a hypertrophic nonunion. However, this patient demonstrates known risk factors for septic nonunion, and initial laboratory evaluation would be prudent to rule out underlying infection.
Answer 4: Supplementation plate fixation could be considered in limited cases of hypertrophic nonunion, however, exchange nailing offers the added benefit of limited dissection with intramedullary reaming to facilitate fracture union. In any case, the initial laboratory evaluation would be prudent to rule out underlying infection
Answer 5: Performing hardware removal with the placement of bioabsorbable antibiotic beads would be considered appropriate for treating a septic nonunion (with added systemic antibiotics as indicated). However, initial laboratory evaluation including inflammatory markers would be prudent to aid in establishing the diagnosis and for appropriate pre-operative planning.