Exchange Intramedullary Nailing for Long-Bone Nonunion

Indication. Symptomatic aseptic hypertrophic or oligotrophic diaphyseal nonunion of the femur or tibia — persistent pain on weight-bearing with no radiographic callus progression — after the original reamed intramedullary nail, once infection has been rigorously excluded. The hypertrophic pattern signals a viable biological response that should respond to the combined mechanical and biological stimulus of a larger reamed nail. Absolute indications:

• Aseptic hypertrophic or oligotrophic diaphyseal nonunion of the femur or tibia with a viable biological response after exclusion of infection.
• A failed or undersized index nail with persistent pain, instability or lack of radiographic progression at greater than 6–9 months.
• A nonunion with acceptable alignment (less than 5 degrees varus/valgus, less than 10 degrees procurvatum/recurvatum) that can be maintained during the exchange. Relative indications:
• Atrophic nonunion with poor biology, when combined with bone grafting or adjunctive stimulation.
• Nonunion with moderate bone loss (less than 1 cm) where reaming debris can provide local autograft.
• Patient preference for a minimally invasive biological solution before considering open plating or transport. Contraindications.
• Absolute — active or suspected infection (elevated inflammatory markers, a draining sinus, positive cultures), which requires staged debridement and antibiotic management; severe bone loss greater than 2–3 cm or a segmental defect requiring bone transport or the Masquelet technique; and gross malalignment or malrotation that cannot be corrected through the existing nail tract.
• Relative — a poor soft-tissue envelope or active ulceration over the proposed nail tract, severe osteoporosis or a narrow canal precluding adequate reaming and fill, and a non-compliant patient unable to follow a protected weight-bearing protocol. The decision: exchange nailing, plating, or transport? The choice turns on biology, bone loss and the soft-tissue envelope:

Consent specifically for the lower but real risk of persistent nonunion (higher in the tibia and in smokers), infection (2–5 percent even in apparently aseptic cases), fat embolism during femoral reaming, iatrogenic fracture, rotational malalignment, and the possibility of further surgery — repeat exchange, plating with graft, or bone transport. Setup. Supine on a radiolucent table, the affected limb free-draped with the contralateral limb also accessible for comparison. For femoral nailing a traction table or a femoral distractor with a well-padded perineal post may be used; for tibial nailing a bump under the ipsilateral hip aids rotational control and the foot is left free for length assessment. The image intensifier sits on the contralateral side, able to capture anteroposterior and lateral views of the whole bone. Confirm that extraction instruments, sharp flexible reamers and an exchange nail 1.5–2 mm larger are available before draping.

The goal is to remove the original nail, ream the canal sequentially to a larger diameter, and insert a stiffer exchange nail that both stabilises the nonunion and deposits osteogenic reaming debris at the site — while protecting the structures at risk at every step. The exposure is laid out in full below (and in depth on the anterolateral approach to the femoral shaft and anteromedial approach to the tibial shaft pages).

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Rehabilitation | Phase | Timing | Weight-bearing | Therapy | |-------|--------|----------------|---------| | 1 | 0–4 weeks | Touch weight-bearing; progress to partial (20–30 kg) as pain allows | Gentle active/active-assisted knee and ankle ROM; isometric quads and hamstrings | | 2 | 4–12 weeks | Partial, advancing toward full when bridging callus appears (6–12 weeks) | Resistance and gait training; tibial cases protected longer (8–12 weeks) | | 3 | 3–6 months | Full weight-bearing when bridging callus is visible on two views | Functional testing (single-leg stance, step-up) before return to work or sport | | 4 | Beyond | Maintenance | Dynamisation considered only after 3–4 months if there is no progression and the nonunion is axially stable | Elevate the limb for the first 48–72 hours and use multimodal analgesia. Monitor the wound at 48 hours and 2 weeks; any erythema, drainage or fever prompts urgent CRP and a wound swab, with perioperative antibiotics continued for 24–48 hours unless cultures were positive. Bone stimulators (low-intensity pulsed ultrasound or pulsed electromagnetic fields) may be considered for high-risk tibial nonunions after 3 months. Smoking cessation is critical — continued smoking roughly doubles the risk of persistent nonunion — alongside nutritional optimisation (vitamin D, calcium, protein) and glycaemic control in diabetics. Complications

Rationale and biological effect. Exchange nailing addresses both requirements for union at once. Mechanically, reaming to a larger diameter increases the moment of inertia and bending stiffness of the implant (stiffness is proportional to the fourth power of the radius), and the larger nail fills the canal more completely. Biologically, the reaming debris provides a local autograft — osteoprogenitor cells, growth factors and a scaffold — that stimulates the healing response in a viable nonunion. The same procedure therefore corrects the mechanical and biological failure modes in the majority of aseptic cases. Femoral versus tibial outcomes. Femoral exchange nailing consistently achieves union rates greater than 90 percent in aseptic hypertrophic nonunions when infection is excluded and adequate stability is obtained; a systematic review reported a mean time to union of 6–8 months with low complication rates. Tibial exchange nailing is less reliable, achieving union in 70–85 percent of cases — the lower rate is attributed to the poorer soft-tissue envelope, the more dependent blood supply and the higher incidence of open injuries in tibia nonunions. Comparison with alternatives. Compression plating offers direct visualisation, the ability to apply absolute stability and bone graft, but needs extensive exposure and carries a higher infection risk in previously operated limbs. Bone transport (Ilizarov or monolateral) is preferred when bone loss exceeds 2–3 cm or the soft-tissue envelope is severely compromised. The Masquelet induced-membrane technique is an alternative for large defects but requires two stages and is more invasive than exchange nailing for contained nonunions.