Non-union of bone is the body’s inability to heal a fracture. Commonly used is the FDA definition of non-union that states non-union is fracture that persists for a minimum of nine months without signs of healing for three months. 1
The rate of all fracture non-unions is between 1.9% and 10%. Variable rates of non-union exist depending on the anatomic region. Femoral shaft non-unions are estimated to be 8% overall with the use of intramedullary nailing. Tibial shaft non-unions occur at a rate of 4.6% after intramedullary nailing. However, there are several discrepancies, as some studies have shown tibia non-union to be as high as 10% to 12% overall. Soft tissue damage negatively impacts the ability to heal bone. Studies of open fractures with extensive soft compromise showed non-unions to be much higher at 16%.
The pathophysiology of a bone non-union is multifactorial 2:
- Inadequate fracture stabilization and poor blood supply lead to non-union
- Infection can lea dto non-union and infection eradication needs to occur prior to or at the same time with achieving fracture union
- Scaphoid, distal tibia, base of the 5th metatarsal bone are at higher risk for non-union because of insufficient blood supply in these areas after fracture
- Segmental fractures and those with loose fragments have an increased risk of non-union like because of compromise of the blood supply to the intercalary segment
Four types of bone non-union have been described 3:
1. Atrophic non-union:
- Evidenced by radiographic absent callus, which indicates poor biology and a lack of blood supply
- Might be a result of inadequate fixation
2. Hypertrophic non-union:
- Shown by radiographic abundant callus formation
- Importantly, there is no bridging bone, and the ends are not united
- This finding implies there is adequate blood supply and biology (with the formation of callus), but inadequate stability
3. Oligotrophic non-union:
- Is a balance and combination of atrophic and hypertrophic in that there is incomplete callus formation
- Inadequate reduction
4. Septic non-union:
- Reduces blood flow from organisms consuming the nutrition to healthy bone
- Decreases the new bone formation
Treatment of non-unions is multidimensional and can consist of conservative treatment followed by operative treatment 4.
- Use of a fracture brace or immobilization in a cast postoperatively
- Pulsed low-intensity ultrasound or other Ilizarov bone transport
Treatment is tailored on non-union type. Multiple surgical techniques exist and they need to be tailored to the patient’s specific needs.
Treatment goal is to improve mechanical stability with internal fixation
- Compression plates
- Exchange nailing
- Augmented plating with ORIF
- Dynamization with a nail
Treatment goal is to repair biology and mechanical stability
- Internal fixation with biologic stimulation
- Biologic stimulation with bone graft
- Bone morphogenetic protein (BMP):
- Autologous iliac crest bone graft
- Intramedullary reaming, irrigation, and debris aspiration (RIA)
- Demineralized bone matrix (DBM)
- Systemic parathyroid hormone (PTH) therapy, teriparatide
Can use a combination of both internal fixation and biologic stimulation depending on the clinical situation
Infected nonunion: Must obtain WBC, ESR, CRP, and nuclear bone scan. Intraoperative cultures are the gold standard for guided antibiotic therapy
- A 2-staged surgical treatment protocol is the gold standard
- 1st stage – removal of loose or chronic infected hardware, debridement, and revision fixation of nonunion, and treatment of infection with culture-specific local and systemic antibiotics
- Modalities used for initial fixation in case of infection
- Antibiotic beads
- Antibiotic nails
- Antibiotic cement spacers
- Masquelet technique
- External fixation
- Soft tissue coverage with a flap
- 2nd stage
- Begins after a period of antibiotic therapy when both serologic and clinical signs of infection are absent
- Definitive fixation proceeds with internal fixation and bone grafting, other biological treatment, bone transport, depending on specific fracture characteristics.
- Cunningham BP, Brazina S, Morshed S, Miclau T. Fracture healing: A review of clinical, imaging and laboratory diagnostic options. Injury. 2017 Jun;48 Suppl 1:S69-S75.
- Brinker MR, O’Connor DP, Monla YT, Earthman TP. Metabolic and endocrine abnormalities in patients with nonunions. J Orthop Trauma. 2007 Sep;21(8):557-70.
- Bell A, Templeman D, Weinlein JC. Nonunion of the Femur and Tibia: An Update. Orthop. Clin. North Am. 2016 Apr;47(2):365-75.
- Garnavos C. Treatment of aseptic non-union after intramedullary nailing without removal of the nail. Injury. 2017 Jun;48 Suppl 1:S76-S81.