Non-union

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.

Conservative treatment:

  • Use of a fracture brace or immobilization in a cast postoperatively
  • Pulsed low-intensity ultrasound or other Ilizarov bone transport

Operative treatment:

Treatment is tailored on non-union type. Multiple surgical techniques exist and they need to be tailored to the patient’s specific needs.

Hypertrophic nonunion

Treatment goal is to improve mechanical stability with internal fixation

    • Compression plates
    • Exchange nailing
    • Augmented plating with ORIF
    • Dynamization with a nail

Atrophic nonunion

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

Oligotrophic nonunion:

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.

References

  1. 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.
  2. 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.
  3. Bell A, Templeman D, Weinlein JC. Nonunion of the Femur and Tibia: An Update. Orthop. Clin. North Am. 2016 Apr;47(2):365-75.
  4. Garnavos C. Treatment of aseptic non-union after intramedullary nailing without removal of the nail. Injury. 2017 Jun;48 Suppl 1:S76-S81.