Perilunate Dislocation — Open Reduction and Internal Fixation

The diagnosis is a surgical emergency. Acute perilunate and lunate dislocations (Mayfield Stage II to IV) are unstable, high-energy carpal injuries with a real threat to the median nerve and to long-term wrist function. Once recognised, they need reduction and combined open stabilisation — closed treatment alone leaves residual instability, missed nerve compression, and a near-certain slide into scapholunate advanced collapse (SLAC). Absolute indications

• Acute perilunate or lunate dislocation (Mayfield Stage II to IV) with or without median nerve compression
• Failed closed reduction, or recurrent instability after closed reduction
• Open perilunate injury with contamination or associated lacerations
• Acute carpal tunnel syndrome with objective sensory or motor deficit persisting after attempted closed reduction Relative indications
• Greater-arc injuries (trans-scaphoid, trans-triquetral, trans-capitate perilunate fracture-dislocations) requiring anatomic scaphoid reduction
• Delayed presentation (greater than 24 hours) with significant swelling where closed reduction is unsafe
• Associated distal radius fracture requiring simultaneous fixation Contraindications. Absolute: life-threatening polytrauma precluding timely wrist surgery (stabilise the patient first), active infection at the surgical site, or patient refusal and inability to comply with post-operative immobilisation. Relative: a low-demand elderly patient with a chronic dislocation greater than 6 weeks and minimal symptoms (consider salvage rather than reconstruction), or severe medical comorbidities increasing surgical risk. Timing is the single biggest determinant of outcome. Best results come when the carpus is reduced within 6 hours of injury (Herzberg 1993). Median nerve recovery is time-dependent — permanent sensory loss rises sharply after 8 hours of compression. Delayed presentation (greater than 24 hours) increases infection risk and the technical difficulty of reduction because of soft-tissue swelling and organising haematoma. Why a combined dorsal AND volar approach. The combined approach gives complete visualisation of both the dorsal and volar ligamentous injuries and allows direct median nerve decompression. Single-approach techniques (dorsal only or volar only) carry higher rates of residual instability and missed median nerve compression; a 2018 systematic review (Mallett 2018) found combined approaches achieved anatomic reduction in 85 percent of cases versus 60 percent with single approaches. Fixation choices. Headless compression screws for trans-scaphoid injuries give superior compression and earlier mobilisation than K-wires alone. Suture-anchor repair of the dorsal scapholunate ligament improves radiographic outcomes at 2 years compared with K-wire stabilisation alone (Pappou 2021). Setup. Supine on a radiolucent table with the arm abducted 90 degrees on a hand table. An upper-arm tourniquet is applied but NOT inflated until the skin incisions are made, so vessels and nerves can be identified in a bloodless field only after exposure. Image intensifier set for true AP, lateral and oblique wrist views. General anaesthesia with a regional block (supraclavicular or axillary) for post-operative analgesia — WALANT is not appropriate for this complex combined procedure. Consent. Discuss median nerve injury (5 to 10 percent permanent deficit risk), infection (less than 2 percent), stiffness (30 to 40 percent), post-traumatic arthritis (greater than 50 percent at 5 years), scaphoid nonunion (10 to 20 percent in trans-scaphoid injuries), and the possible future need for salvage procedures (proximal row carpectomy or total wrist arthrodesis).

The goal is to anatomically reduce the carpus, restore both the dorsal and volar ligamentous rings, fix any associated fracture (usually the scaphoid), and decompress the median nerve — through a combined dorsal then volar exposure. The dorsal side is opened first because the scapholunate and lunotriquetral intervals must be reduced and fixed under direct vision; the volar side then repairs the space of Poirier rent and decompresses the nerve. The exposure is laid out in full below.

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Rehabilitation | Phase | Timing | Immobilisation | Therapy | |-------|--------|----------------|---------| | Immobilisation | 0 to 8 (or 12) weeks | Short-arm thumb spica cast, neutral wrist; 8 weeks for K-wire stabilisation, 12 weeks if ligament repair is poor or bone graft used | Strict elevation 48 to 72 hours; immediate active finger, elbow and shoulder motion; sutures out at 10 to 14 days | | Protected motion | 8 to 12 weeks | K-wires removed at 8 weeks under local anaesthesia (fluoroscopic confirmation first); removable wrist splint for comfort | Gentle active-assisted wrist flexion-extension and pronosupination; thumb spica component to 12 weeks if scaphoid fixed; scar massage and desensitisation from 2 weeks | | Strengthening | 12 to 24 weeks | Splint for heavy tasks only | Progressive grip and pinch strengthening with putty; light duties at 12 to 16 weeks, manual work at 16 to 24 weeks | | Return to activity | by 6 months | None if union and stability confirmed | Full unrestricted activity once radiographic union and clinical stability are confirmed | Serial radiographs are taken at 6 weeks, 3 months, 6 months and 1 year to monitor for SLAC progression or hardware failure. Complications

Long-term surveillance. Review clinically and radiographically annually for the first 5 years to detect early SLAC change. Counsel every patient that even with anatomic reduction, post-traumatic arthritis develops in greater than 50 percent by 5 years and greater than 70 percent by 10 years, and that salvage options (proximal row carpectomy, four-corner fusion, total wrist arthrodesis) remain available when symptomatic arthritis develops.

Mechanism. Perilunate injuries result from high-energy hyperextension, ulnar deviation and intercarpal supination — typically a fall from height or a motor-vehicle collision. The capitate is driven dorsally while the lunate is tethered volarly by the radiolunate ligaments, tearing the perilunar ligamentous ring in a reproducible sequence (the Mayfield stages). A lesser-arc injury is a pure ligamentous failure around the lunate (Mayfield I to IV); a greater-arc injury includes an associated fracture through the scaphoid, capitate and/or triquetrum, and the fracture is reduced and fixed in the same sitting.

Critical anatomy. Dorsal: the dorsal scapholunate ligament is the primary stabiliser of the scapholunate interval and its repair determines long-term outcome; the dorsal radiocarpal and dorsal intercarpal ligaments form a V-shaped stabilising complex that must be preserved or repaired; the dorsal sensory branches of the radial and ulnar nerves cross the surgical field. Volar: the space of Poirier is the weak point between the radioscaphocapitate and long radiolunate ligaments and is the site of the volar capsular rent; the median nerve lies immediately volar to a displaced lunate and its recurrent motor branch must be protected during carpal tunnel release. Blood supply: the lunate is supplied by dorsal and volar branches of the radial artery, so complete dislocation can disrupt both and cause osteonecrosis in 5 to 10 percent; the proximal pole of the scaphoid has a tenuous retrograde blood supply, making anatomic reduction and stable fixation critical to avoid avascular necrosis. Key evidence. Herzberg's multicentre study (1993) established that anatomic reduction within 6 hours gives the best outcomes and that median nerve compression is present in 25 percent at presentation. Komurcu (2008) showed that headless compression screw plus bone graft lowers the nonunion rate versus K-wires alone in trans-scaphoid injuries, and George (2020) confirmed good to excellent functional outcomes when anatomic reduction is achieved — while counselling that arthritis risk remains high even then.