Distal Radius External Fixation (Spanning and Non-Spanning)

Indication. External fixation is chosen when the fracture pattern or the patient makes prolonged open reduction and internal fixation undesirable — either as definitive treatment or as a damage-control bridge. Absolute indications - Severely comminuted intra-articular distal radius fractures (AO C2-C3) where anatomic reduction and stable internal fixation cannot be achieved.

• Open or contaminated distal radius fractures requiring damage-control surgery with delayed definitive fixation.
• Polytrauma patients who are physiologically unstable for prolonged ORIF (damage-control orthopaedics).
• Distal radius fractures with associated severe soft-tissue injury precluding immediate open surgery. Relative indications - Adjunct to limited internal fixation (K-wires or volar plating) when additional stability is required.
• Patients with poor bone quality or medical comorbidities where prolonged surgery is undesirable.
• Selected extra-articular fractures with significant shortening or dorsal comminution in young active patients. Contraindications. Absolute: a distal fragment too small or osteoporotic to accept two half-pins (non-spanning); active infection at planned pin sites; patient non-compliance with pin-site care or follow-up. Relative: simple extra-articular fractures amenable to closed reduction and casting; volar shear fractures (AO B3) better treated with volar buttress plating; patient preference for definitive internal fixation when conditions allow. The one decision that matters — spanning or non-spanning. Every external fixator shares the same proximal anchor (two half-pins in the radial shaft). The only real choice is where the distal pins go, and that choice follows the fracture:

Consent specifically for pin-site infection (5-15 percent), radial sensory neuritis (3-8 percent), finger stiffness and CRPS, loss of reduction, the need for frame adjustment or removal, and the possibility of later conversion to internal fixation. Setup. Supine on a radiolucent table with the arm abducted 90 degrees on a hand table; the C-arm enters from the opposite side. Upper-arm tourniquet applied but inflated only if open reduction is planned. Regional (axillary or supraclavicular) block or general anaesthesia — WALANT is unsuitable because of the discomfort of pin insertion and frame manipulation. Equipment: 3.5 mm or 4.0 mm self-drilling half-pins, external fixator clamps and carbon-fibre rods, 2.0 mm and 2.5 mm drill bits, pin cutters, and a small-fragment K-wire set.

The goal is to restore radial length, palmar tilt and radial inclination — directly for non-spanning constructs, or indirectly through ligamentotaxis for spanning frames — while protecting the superficial radial nerve, the extensor tendons and the radial artery, and never over-distracting the carpus. The exposure here is percutaneous: the corridors in which the pins are placed, and the danger structures that bound them, ARE the dissection.

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Rehabilitation | Phase | Timing | Immobilisation and care | Therapy and milestones | |-------|--------|-------------------------|------------------------| | Immediate | Day 0-7 | Elevate above heart level for 48-72 hours; pin-site care (chlorhexidine or isopropyl alcohol twice daily after the first 48 hours, no occlusive dressings) | Active finger flexion and extension from day 1 (10 repetitions hourly); first review at 48-72 hours with a radiograph | | Early | Week 1-4 | Continue pin-site care; weekly pin inspection, oral antibiotics for any erythema; no lifting greater than 2 kg | Gentle active wrist and forearm motion if non-spanning (spanning frames stay immobilised); formal hand therapy from 2 weeks | | Late | Week 4-12 | Spanning frame removed at 6-8 weeks once callus is visible; non-spanning at 4-6 weeks | Progressive active and passive wrist mobilisation, grip strengthening, scar desensitisation after removal | | Return to function | Week 8-16 | — | Light work at 8-10 weeks; heavy manual work at 12-16 weeks; final assessment at 3-6 months with DASH and PRWE scores | Frame care instructions for patients: keep pin sites clean and dry and report any increasing redness, drainage or fever immediately; do not attempt to adjust or loosen the frame; protect it from impact with a loose stockinette or sleeve outdoors; continue prescribed finger (and, if non-spanning, wrist) exercises daily. Complications

Special situations. Open fractures and polytrauma: external fixation is the damage-control method of choice — thorough debridement, a spanning frame for length and stability, antibiotic prophylaxis and tetanus cover, and definitive fixation delayed until the soft tissues recover (typically 7-14 days). Osteoporotic bone: use smaller pins (2.5-3.0 mm), pre-drill and tap, and consider cement augmentation around pins if purchase is poor; non-spanning constructs are usually contraindicated and spanning frames with supplemental K-wires are preferred. Conversion to internal fixation: when the soft tissues allow (usually 10-21 days), convert to a volar locking plate, removing the external fixator in the same procedure or staging it 1-2 weeks before plate application to reduce infection risk.

Ligamentotaxis — the biomechanical foundation. External fixation restores radial length, inclination and palmar tilt through ligamentotaxis in the majority of cases when over-distraction is avoided. The volar capsule and the radioscaphocapitate, long radiolunate and short radiolunate ligaments remain attached to the distal fragment in most patterns, so traction through an intact capsule reduces the articular surface and restores length, palmar tilt and radial inclination indirectly. The dorsal capsule is thinner and contributes less; excessive dorsal comminution may require supplemental dorsal bone grafting or K-wires. Spanning frames are the workhorse for highly comminuted or open injuries, while non-spanning frames preserve more wrist motion but demand adequate distal bone stock. Combining the frame with percutaneous K-wires or limited open bone grafting improves articular-surface reduction and reduces late collapse. Osseous anatomy that shapes the technique. The distal radius has a triangular cross-section with a relatively thin dorsal cortex and a thicker volar buttress — which is why dorsal comminution is common and why non-spanning constructs need at least 1 cm of intact volar cortex. The radial styloid gives attachment to brachioradialis and the radial collateral ligament complex. The dorsal surface carries the four extensor compartments, with the EPL tendon in the third compartment directly over the distal radius; the volar surface is covered by pronator quadratus and the flexor tendons, with the radial artery lying between brachioradialis and FCR. Outcomes and complications. Pin-site infection rates range from 5-15 percent in published series; most resolve with oral antibiotics and local care, but deep infection requiring frame removal occurs in 1-3 percent. Radial sensory neuritis occurs in 3-8 percent and is largely preventable with careful pin placement and blunt dissection. Finger stiffness and CRPS are more common with prolonged over-distraction, so early motion and avoidance of excessive traction are critical. Loss of reduction after frame removal is reported in 10-20 percent of highly comminuted fractures treated with external fixation alone, and supplemental K-wires or bone graft reduce this risk.