Distal Radius Corrective Osteotomy (Malunion)

Indication. A distal radius malunion becomes a surgical indication when ALL THREE of the following are present — deformity beyond acceptable limits, symptoms attributable to that deformity, and failure of non-operative management (rest, activity modification, hand therapy, a trial of splinting or medication). Deformity thresholds that justify surgery:

• Dorsal tilt greater than 10-15 degrees, radial shortening greater than 3-5 mm, loss of radial inclination greater than 5 degrees, or an intra-articular step greater than 2 mm. Absolute indications. Dorsal angulation greater than 20-25 degrees with significant functional impairment and no radiocarpal arthritis; radial shortening greater than 5 mm with positive ulnar variance and ulnocarpal abutment; an intra-articular step greater than 2 mm in a young patient (under 45-50) with a discrete fragment and preserved cartilage; disabling DRUJ dysfunction (loss of pronosupination, painful clicking, arthrosis) at least partly due to the malunion; and midcarpal instability (VISI) secondary to the malunion. Relative indications. Radial shortening 3-5 mm with mild-to-moderate symptoms; dorsal tilt 10-20 degrees with weakness; concurrent carpal tunnel syndrome from the malunited volar cortex (a volar osteotomy decompresses simultaneously); and patient preference for correction after detailed counselling. Contraindications. Absolute: established radiocarpal or DRUJ arthritis (a salvage procedure — partial/total wrist fusion or arthroplasty — is preferred), active infection, or medical unfitness for anaesthesia with no reversible component. Relative: a heavy smoker unwilling to stop (markedly elevated nonunion risk — offer a cessation programme first), pre-existing complex regional pain syndrome (predicts worse outcomes — proceed cautiously), significant osteopenia that may compromise fixation, and low functional demand with tolerable symptoms. Consent. Discuss nonunion, under- or over-correction, tendon rupture (FPL, EPL), neurovascular injury (median nerve, radial artery), DRUJ symptoms persisting, plate-related symptoms requiring removal, complex regional pain syndrome, stiffness, and the prolonged recovery — often 6-12 months to maximal improvement. Setup. Supine, arm abducted on a hand table, upper-arm tourniquet (250-300 mmHg), image intensifier on the opposite side with full AP and lateral access throughout. General or regional (axillary brachial plexus) anaesthesia; consider a supplemental regional catheter for post-op analgesia. Pre-operative templating is mandatory: bilateral PA, lateral and oblique radiographs; CT with 3-D reconstruction for any complex or multiplanar deformity; measure the contralateral radial height, volar tilt, inclination and ulnar variance; and calculate the osteotomy wedge size, location and correction angle. Patient-specific cutting guides and pre-contoured plates can be manufactured from the CT data.

The goal is to restore the three radiographic parameters, neutralise ulnar variance and address any DRUJ pathology — in one operation. The workhorse for the common dorsal (Colles) malunion is the volar opening-wedge osteotomy: expose the distal radius through a volar Henry approach, cut the metaphysis leaving the dorsal cortex as a hinge, open the wedge to the templated height, pack in a structural graft, and lock a volar plate with its distal edge proximal to the watershed line.

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Variation: dorsal closing-wedge osteotomy (for volar / Smith angulation) - Indication. Volar angulation (Smith pattern) — uncommon.

• Exposure — dorsal. Longitudinal incision centred over Lister's tubercle; release the EPL sheath and retract the EPL tendon; reflect the extensor retinaculum to expose the third and fourth extensor compartments. A posterior interosseous nerve (PIN) neurectomy is often added to denervate the dorsal wrist capsule.
• Cuts. Plan a closing-wedge on the lateral view with the base dorsal and the apex on the volar cortex; make two parallel transverse metaphyseal cuts leaving the volar cortex intact as a hinge, remove the wedge, and close the osteotomy.
• Fixation. A low-profile dorsal plate (to reduce EPL attrition), or K-wires plus a volar neutralisation plate; confirm the correction on fluoroscopy.

Variation: intra-articular osteotomy - Indication. A young patient (typically under 45) with a discrete intra-articular step greater than 2 mm, no radiocarpal arthritis, and fragments large enough to hold fixation; best performed within 6-12 months of injury.

• Technique. Volar or dorsal approach depending on the step; capsulotomy to expose the joint; mobilise the displaced fragment and reduce it anatomically under direct vision; fix with headless compression screws, mini-fragment plates or K-wires; confirm reduction with arthroscopy and fluoroscopy. Outcomes are best when cartilage is preserved and correction is early; long-term post-traumatic arthritis risk remains higher than after extra-articular osteotomy. ## Concurrent DRUJ procedure - Decision. Indicated when there is positive ulnar variance with ulnocarpal abutment and/or DRUJ arthrosis; the choice depends on TFCC status, arthrosis, ulnar variance and patient factors.
• Ulnar shortening osteotomy (most common). Separate incision over the distal ulna; transverse or oblique diaphyseal osteotomy; shorten to neutral variance (0-1 mm); dedicated 6-7 hole compression plate.
• Wafer resection (distal ulna arthroplasty). For positive ulnar variance less than 4 mm with TFCC pathology amenable to repair; resect 2-4 mm of the distal ulnar head through a small arthrotomy, preserving the ulnar styloid base and TFCC attachments (arthroscopic option).
• Sauvé-Kapandji. For DRUJ arthrosis with positive variance, or failed ulnar shortening; a distal radioulnar arthrodesis with creation of a proximal ulnar pseudarthrosis (resect 1-1.5 cm of ulna proximal to the arthrodesis).
• Order of procedures. Many surgeons fix the ulnar side first, then correct the radius, so the final ulnar length is confirmed before the radial correction is set.

Rehabilitation | Phase | Timing | Immobilisation | Therapy | |-------|--------|----------------|---------| | 1 | 0–14 days | Short-arm volar splint, wrist neutral | Active finger flexion/extension from day 1; elevation and oedema control; wound check at 48–72 h | | 2 | 2–6 weeks | Removable wrist splint for comfort; sutures out at 10–14 days | Formal hand therapy from 2–4 weeks — active and passive wrist ROM, scar care; radiographs at 2 and 6 weeks | | 3 | 6–12 weeks | Splint for heavy tasks only | Grip strengthening from 6 weeks once union is evident; return to light activities at 6–8 weeks | | 4 | 12 weeks+ | Night splint only if needed | Graded return to manual work and sport at 3–6 months; plate removal (if symptomatic) at 6–12 months | Rehabilitation goals are wrist flexion 60-70 degrees and extension 50-60 degrees, pronation and supination 70-80 degrees each, and grip strength to 70-80 percent of the contralateral side. Most patients return to desk work by about 6 weeks and to manual work by 3-6 months.

The deformity is three-dimensional. A distal radius malunion is a three-plane problem — the classic teaching is to address three radiographic parameters, but the real deformity may include components in the sagittal, coronal and axial planes plus rotation. The operative targets and thresholds: | Parameter | Normal | Significant malunion threshold | Surgical target | |-----------|--------|--------------------------------|-----------------| | Volar tilt | 11 degrees (range 8-12) | Dorsal tilt greater than 10-15 degrees | Restore to within 5 degrees of normal | | Radial height | 11-12 mm | Shortening greater than 3-5 mm | Restore to within 2 mm of contralateral | | Radial inclination | 22-23 degrees | Loss greater than 5 degrees | Restore to normal | | Ulnar variance | 0-1 mm neutral | Positive greater than 2 mm | Neutralise | | Intra-articular step | 0 mm | Step greater than 2 mm | Less than 1 mm | | Radial rotation | Aligned with ulna | Malrotation of the distal fragment | Restore alignment | Pattern recognition. The Colles pattern (dorsal angulation, radial shortening, loss of inclination) is by far the most common and is treated with a volar opening-wedge at the metaphysis. The Smith pattern (volar angulation) is less common and is treated with a dorsal closing-wedge. A Barton-type intra-articular malunion is rare — intra-articular osteotomy only in young patients with preserved cartilage. A die-punch malunion (a depressed lunate facet fragment) is technically demanding intra-articular correction. Osseous anatomy. The osteotomy belongs in the metaphysis — distal to the pronator quadratus insertion, proximal to the subchondral bone. The volar cortex is the shortened side in a typical Colles malunion, which is where the opening-wedge is made. The watershed line is a transverse volar ridge 2-3 mm proximal to the articular surface; the distal edge of any volar plate must lie proximal to it. Neurovascular anatomy. In the volar approach, the median nerve, FPL, radial artery and the palmar cutaneous branch of the median nerve are at risk. In the dorsal approach, the EPL (third compartment), extensor compartments 2-4, the PIN (often resected for capsular denervation) and the dorsal branch of the ulnar nerve are at risk. DRUJ anatomy — the TFCC, the dorsal and volar radioulnar ligaments, the ulnar styloid (base non-union is common but usually asymptomatic) and the ECU subsheath — must all be assessed when ulnar-sided pathology is suspected. Carpal alignment. A malunion with dorsal tilt produces a compensatory carpal malalignment — most often a dorsal intercalated segment instability (DISI), less often a volar intercalated segment instability (VISI, which may signal scapholunate or lunotriquetral injury). Correcting the radial tilt usually resolves the adaptive carpal malalignment. A dorsal tilt greater than 20-30 degrees can produce a volar midcarpal instability with a painful clunk; restoring volar tilt is the key to managing it.

Outcomes of corrective osteotomy. Pooled case-series evidence (systematic review, Lozano-Calderon 2006, PENDING PMID) reports approximately 70-90 percent good-to-excellent results for pain relief and restoration of grip strength. Most series report 60-80 percent of patients achieving meaningful pain reduction, an average grip-strength improvement of 30-50 percent of the contralateral side, and modest gains in the flexion-extension arc (typically 10-20 degrees), with more predictable correction of pronosupination when the DRUJ is addressed. 3-D CT templating with custom guides improves accuracy — the standard deviation of angular correction falls from approximately 5 degrees (free-hand) to 2 degrees (guided) in comparative series — and patient-specific plates allow precise pre-contoured fixation, particularly in multiplanar deformity.