Wrist Arthrodesis (Total, 4-Corner & PRC)

Procedure Selection by Pathology

The three wrist salvage procedures address different points on the spectrum of carpal degenerative arthritis. The choice is driven by the pattern of cartilage destruction (SLAC vs SNAC stage), the state of the capitate head and radiolunate joint, patient age, occupation, and functional demands.

Indications in Detail

Total Wrist Arthrodesis

• End-stage SLAC wrist (Stage III–IV) with capitolunate arthritis
• End-stage SNAC wrist with extensive carpal collapse
• Pancarpal arthritis (rheumatoid, septic, post-traumatic)
• Failed partial arthrodesis (failed 4-corner, non-union)
• Chronic infection requiring definitive stabilisation
• Young heavy-labouring patients requiring maximum stability
• Patients who cannot comply with post-operative rehabilitation (cognitive impairment)
• Neuromuscular disease with spastic wrist deformity

4-Corner Arthrodesis (Lunocapitate-hamate-triquetrum fusion + scaphoid excision)

• SLAC wrist Stage II–III or SNAC wrist Stage II–III
• Intact radiolunate articular cartilage (confirmed on MRI and at arthrotomy)
• Patient who values residual wrist motion
• Demanding occupation requiring some wrist ROM

Proximal Row Carpectomy

• SLAC Stage I–II or SNAC Stage I–II
• Confirmed intact capitate head cartilage on MRI and at arthrotomy
• Older or lower-demand patient
• Patient who values faster recovery and simpler rehabilitation
• Failed scaphoid reconstruction without advanced arthritis

Evidence Summary

Procedure Decision Algorithm

The following algorithm summarises the decision process for selecting between the three procedures:

Step 1: Establish SLAC or SNAC stage from X-ray (AP and lateral wrist, scaphoid views) and MRI.

Step 2: Assess radiolunate cartilage — if preserved (normal signal on MRI, confirmed normal at arthrotomy), partial procedures are anatomically feasible.

Step 3: Assess capitate head cartilage — if preserved, PRC is technically possible; if damaged, only 4-corner or total fusion remain.

Step 4: Consider patient factors — age, occupation, dominant versus non-dominant hand, physical demands, compliance with prolonged immobilisation required for 4-corner union confirmation.

Step 5: Discuss all options with patient pre-operatively including: motion expectations, grip strength outcomes, non-union risk (4-corner), recurrence/conversion rate, and total fusion as definitive fallback. Informed consent must include the possibility of intraoperative conversion to total fusion if cartilage assessment at arthrotomy contradicts pre-operative imaging.

Global Practice Variation

There is no randomised controlled trial comparing these salvage procedures directly; the highest-quality comparative evidence comes from retrospective cohorts and two systematic reviews (Mulford 2009, PMID 19369301; Saltzman 2014, PMID 25294736). Both reviews conclude that PRC and 4-corner fusion give similar pain relief and subjective scores, that PRC gives a larger flexion-extension arc and a lower overall complication rate, and that 4-corner fusion gives slightly better grip-as-a-percentage-of-the-opposite-side and radial deviation but carries the specific risks of non-union, hardware prominence and dorsal impingement. Long-term data (Wall/DiDonna, PMID 23809467) show PRC has a roughly 65% 20-year survivorship, with younger age the main predictor of failure — hence the widely taught caution against PRC in patients under approximately 35 years. AO Surgery Reference, BSSH (UK) and ASSH (US) teaching converge on stage-led selection rather than a single "best" operation, and surgeon training/preference remains a legitimate factor where two options are anatomically valid.

Carpal Kinematics and SLAC/SNAC Patterns

Normal Carpal Row Motion

The wrist moves through a coupled kinematic mechanism. The scaphoid acts as a bridge between the proximal and distal carpal rows. With wrist flexion, the scaphoid flexes; with extension, it extends. Loss of this coupling (scapholunate dissociation or scaphoid nonunion) creates rotary subluxation — the basis of both SLAC and SNAC deformity.

SLAC Wrist — Scapholunate Advanced Collapse

Caused by rotary subluxation of the scaphoid secondary to scapholunate ligament disruption. The distal pole of the scaphoid flexes and translates radially, creating abnormal loading at:

• Stage I: Radial styloid tip articulation with scaphoid distal pole
• Stage II: Entire scaphoid fossa of distal radius (proximal pole contact)
• Stage III: Capitolunate joint — the capitate migrates proximally into the gap between scaphoid and lunate
• Stage IV (rare): Pantrapezial involvement

Key anatomical fact: The radiolunate (radiocarpal) joint is SPARED in SLAC because the lunate, which no longer has the scaphoid controlling it, assumes a dorsiflexed posture (DISI — dorsal intercalated segment instability). The lunate contacts a normal part of the radius. This preservation of the radiolunate joint is the anatomical basis for 4-corner fusion and PRC.

SNAC Wrist — Scaphoid Nonunion Advanced Collapse

Progression pattern identical to SLAC but driven by fibrous nonunion of the scaphoid waist. The distal scaphoid fragment flexes and rotates, driving the same sequence of articular destruction.

• Stage I: Radial styloid–distal scaphoid fragment articulation
• Stage II: Entire scaphoid fossa (radioscaphoid joint)
• Stage III: Capitolunate joint

The Four Carpal Bones Involved in 4-Corner Fusion

The 4-corner fusion fuses: lunate, triquetrum, capitate, hamate — after excision of the scaphoid. This creates a stable central column. The lunate then articulates with the preserved radiolunate facet, providing a residual flexion-extension arc of roughly 60° (about 45–50% of normal in pooled series).

Proximal Row Anatomy for PRC

The proximal row comprises scaphoid, lunate, and triquetrum. After excision of all three bones, the capitate head (normally articulating with the lunate in the distal row) descends into the lunate fossa of the radius. This pseudarthrosis provides pain-free motion if the capitate head articular cartilage is intact.

Dorsal Approach Anatomy

The standard dorsal approach to the wrist uses the interval between the 3rd (EPL) and 4th (EDC) extensor compartments. Key structures at risk:

• Dorsal sensory branches of the radial nerve (superficial, dorsoradial): must be identified and protected
• Posterior interosseous nerve (PIN): lies on the floor of the 4th compartment — often intentionally resected for denervation pain relief during total wrist fusion
• Extensor tendons: all six compartments must be identified and retracted

Pre-operative Planning — Imaging Requirements

All patients undergoing wrist salvage procedures require:

Gripping AP view: Applying axial compression through the clenched fist loads the capitolunate joint and may unmask Stage III arthritis not visible on standard views. This is particularly important when staging is uncertain between Stage II and Stage III.

Patient Counselling — Key Points for All Three Procedures

Patients undergoing wrist salvage procedures must understand:

• None of the three procedures restores normal wrist function — they are pain-relieving salvage operations
• Grip strength will be reduced compared to the normal contralateral side in all procedures
• Total wrist fusion produces the most reliable pain relief but sacrifices all wrist motion permanently
• Partial procedures (4-corner, PRC) preserve some motion but may require conversion to total fusion
• Return to heavy manual labour is possible after total wrist fusion but not usually expected after partial procedures requiring union confirmation

All Three Procedures — Step-by-Step

SHARED SETUP (All Three Procedures)

• Patient supine, arm on hand table, tourniquet to upper arm (250 mmHg)
• Exsanguinate with Esmarch bandage or arm elevation
• Dorsal longitudinal incision centered over the radiocarpal joint
• Open extensor retinaculum in 3rd–4th compartment interval (EPL and EDC)
• Protect dorsal sensory radial nerve branches in subcutaneous tissue
• Identify and optionally resect PIN on floor of 4th compartment (provides denervation analgesia)
• Elevate dorsal wrist capsule as capsular flap based on the radius

PROCEDURE A — PROXIMAL ROW CARPECTOMY (PRC)

Simplest technique — no fusion required

Step 1: Confirm capitate head articular cartilage is macroscopically normal at arthrotomy — if damaged, abandon PRC and proceed to 4-corner or total fusion.

Step 2: Excise the scaphoid first. Detach the scapholunate and scaphocapitate attachments, but preserve the volar radioscaphocapitate (RSC) ligament — this is the key palmar sling that prevents ulnar translation of the carpus after PRC. Use rongeur and osteotome to fragment and remove the scaphoid piecemeal to protect surrounding structures. Confirm complete removal with fluoroscopy.

Step 3: Excise the lunate — release radiocarpal ligaments from distal pole. Protect the radiolunate facet articular surface. Remove en bloc or piecemeal.

Step 4: Excise the triquetrum — release lunotriquetral and triquetrohamate ligaments. The pisotriquetral joint does not need to be disrupted. Remove triquetrum.

Step 5: Seat the capitate head into the lunate fossa. Confirm articular congruence with fluoroscopy. No fixation is required. If capitate is unstable, a temporary K-wire (6 weeks) can be used.

Step 6: Repair dorsal wrist capsule with absorbable sutures. Repair extensor retinaculum. Close skin. Apply short-arm thumb spica cast for 6 weeks.

PROCEDURE B — 4-CORNER ARTHRODESIS

Scaphoid excision + lunotriquetrocapitate-hamate fusion

Step 1: Confirm radiolunate articular cartilage is normal at arthrotomy. If damaged, convert to total wrist fusion.

Step 2: Excise the scaphoid as described above. Confirm complete removal fluoroscopically — retained scaphoid fragments will impede the fusion.

Step 3: Denude articular cartilage from all four fusion surfaces: lunate (distal), triquetrum (distal), capitate (proximal), hamate (proximal-medial). Use curette and small rongeur to remove cartilage down to bleeding subchondral bone on all joint surfaces.

Step 4: Apply bone graft (cancellous from distal radius Lister's tubercle resection, or iliac crest) into all fusion intervals.

Step 5: Reduce carpal alignment — lunate in neutral flexion, avoid DISI. Reduce capitate onto the radius-lunate axis under fluoroscopy.

Step 6: Fixation — Circular plate (Spider plate) with headless compression screws is the current gold standard. Circular plate placed centrally spanning all four bones. Headless screws provide compression across each interface. Alternatively: Staples (Acutrak) or K-wires (less stable, higher non-union).

Step 7: Confirm fusion position and hardware placement with intraoperative fluoroscopy. Apply cast for 8–12 weeks until CT confirms union.

PROCEDURE C — TOTAL WRIST ARTHRODESIS

Complete radiocarpal and midcarpal fusion

Step 1: Expose the dorsal wrist widely — identify all extensor compartments. Retract or protect all extensor tendons. Resect Lister's tubercle (provides cancellous graft material AND creates a flatter plate-bed).

Step 2: Strip articular cartilage from distal radius (radiocarpal articular surface), proximal carpal row (scaphoid, lunate, triquetrum — all proximal surfaces), and midcarpal joint surfaces as needed.

Step 3: Position the wrist at 10–20° extension and neutral radial/ulnar deviation. Check position clinically and with fluoroscopy before plate application.

Step 4: Apply AO wrist fusion plate — a pre-contoured plate with 10° built-in extension. Place along dorsal surface from the distal radius to the 3rd metacarpal shaft (middle finger ray is co-linear with the radius). Insert screws: 2–3 cortical screws in distal radius, 2 screws across carpus, 2 cortical screws in 3rd MC shaft.

Step 5: Pack cancellous bone graft from Lister's tubercle into the radiocarpal and midcarpal fusion spaces.

Step 6: Confirm plate position, screw placement, and fusion position with fluoroscopy in two planes. Repair extensor retinaculum and skin. Apply long-arm thumb spica cast for 4 weeks, then short-arm cast until fusion confirmed (usually 10–12 weeks total).

Complications by Procedure

Managing 4-Corner Non-Union

Non-union at 4-corner fusion is the most important complication to know. Diagnosis: persistent pain at 3–6 months, confirmed by CT scan (not X-ray alone — CT required to assess cortical bridging). Management:

• Repeat bone grafting with rigid fixation (revision to circular plate if not already used)
• If failed 4-corner non-union: convert to total wrist fusion
• Inform patient pre-operatively that non-union risk is 10–15% and conversion may be needed

Total Wrist Fusion — DRUJ Assessment

Total wrist fusion fuses the radiocarpal and midcarpal joints but not the distal radioulnar joint (DRUJ). Post-fusion, forearm rotation (pronation/supination) depends entirely on a functional DRUJ. Pre-operative DRUJ assessment with fluoroscopy and examination is mandatory. If DRUJ arthritis is present, concurrent or staged Sauvé-Kapandji or Darrach procedure is required.

Post-operative Protocols

Proximal Row Carpectomy

• Short-arm (± thumb spica) cast for 4–6 weeks
• Begin wrist ROM exercises when cast removed
• Strengthening from 3 months
• Return to full activity: 3–4 months
• Expected final motion: flexion-extension arc ~75° (≈60% of normal; ≈64% in Wyrick series)
• Grip strength: ~67% of contralateral in meta-analysis (up to 80–94% in single-centre series)

4-Corner Fusion

• Short-arm cast for 8–12 weeks minimum until CT confirms union
• Follow-up CT at 8–12 weeks — do not remove cast based on X-ray alone (insufficient sensitivity)
• ROM exercises begin when union confirmed
• Expected final motion: flexion-extension arc ~60° (≈45–50% of normal); radial deviation relatively preserved
• Grip strength: ~74% of contralateral (meta-analysis)
• Full activity: 4–6 months if union achieved

Total Wrist Arthrodesis

• Long-arm cast 4 weeks, then short-arm cast 6–8 weeks further (total 10–12 weeks)
• No wrist ROM (fused) — finger and shoulder ROM from day 1
• Return to light activities at 3 months
• Return to heavy manual work: 4–6 months (confirm solid fusion on X-ray)
• Grip strength: strongest of the three procedures for power grip; most patients accomplish the majority of daily tasks albeit in a modified fashion (Weiss 1995: Jebsen task completion 64% vs 78% normal; 15/23 returned to original job)
• Most patients are satisfied with pain relief; hardest tasks are perineal care and reaching into tight spaces
• Hardware removal: a notable minority require plate removal for dorsal prominence/tendon irritation, usually after union (often after 12 months)

Long-Term Outcomes Data