WRIST ARTHROPLASTY
Motion-Preserving Salvage | RA Primary Indication | Distal Loosening Challenge | Low-Demand Essential
WRIST ARTHROPLASTY INDICATIONS
Critical Must-Knows
- Rheumatoid arthritis is the primary indication - low demands, soft bone, bilateral disease
- Distal component loosening is the most common failure mode (10-30%) - metacarpal stress shielding
- Low-demand patients essential - heavy use accelerates loosening and failure
- Preserves 40-60 degrees motion arc vs arthrodesis which eliminates all motion
- Fusion remains gold standard for high-demand patients due to durability concerns
Examiner's Pearls
- "TWA vs fusion: Motion preservation (TWA) vs durability (fusion) - patient selection critical
- "Distal component loosening most common complication - occurs at metacarpal-carpal junction
- "RA patients ideal: low demands, soft bone accepts cement, often bilateral disease
- "Extensor tendon rupture occurs due to dorsal hardware prominence - 5-10% incidence
Critical Wrist Arthroplasty Exam Points
Patient Selection Critical
Rheumatoid arthritis with low demands is the ideal indication. High-demand patients, young age, and heavy manual labor are relative contraindications. Patient selection is the single most important factor determining outcome. Poor selection leads to early loosening and revision.
Distal Loosening Problem
Distal component loosening is the Achilles heel of TWA (10-30%). Occurs at metacarpal-carpal junction due to stress concentration. Modern third-generation designs address this with improved distal fixation but long-term durability remains inferior to fusion.
Motion Preservation Benefit
Preserves 40-60 degrees arc of motion at wrist. Critical for patients with bilateral disease, contralateral fusion, or occupations requiring wrist motion. However, motion preservation comes at cost of durability - trade-off must be discussed with patient.
Fusion Remains Gold Standard
Arthrodesis preferred for high-demand patients, young patients, and those requiring durability. Fusion eliminates motion but provides reliable pain relief with 95 percent union. TWA revision rate higher than primary fusion rate.
Total Wrist Arthroplasty vs Wrist Arthrodesis
| Feature | Total Wrist Arthroplasty | Wrist Arthrodesis |
|---|---|---|
| Primary Indication | RA, low-demand, bilateral disease | High-demand, OA, post-traumatic |
| Motion | Preserves 40-60 degree arc | Eliminates all wrist motion |
| Durability | 80% survival at 5 years | 95% union rate, durable long-term |
| Main Complication | Distal component loosening (10-30%) | Nonunion (5-10%) |
| Revision Rate | 15-25% at 10 years | 5-10% at 10 years |
| Grip Strength | 50-70% of normal | 60-80% of normal |
| Activity Level | Low-demand activities only | Higher-demand activities possible |
| Bilateral Disease | Ideal - motion both sides | Functional limitation if bilateral |
LOWRATWA Patient Selection
Memory Hook:LOWRA selection: Low demand, Older, Widespread RA with Adequate bone - ideal TWA candidate.
HEAVYTWA Contraindications
Memory Hook:HEAVY contraindications: High demand, Extensor deficiency, Active infection, Very young, Youthful activity - choose fusion instead.
LITERTWA Complications
Memory Hook:LITER of problems: Loosening, Impingement, Tendon rupture, Erosion, Revision - distal loosening is the key failure mode.
Overview and Epidemiology
Definition: Total wrist arthroplasty (TWA) is a motion-preserving salvage procedure for end-stage wrist arthritis. It replaces the radiocarpal and midcarpal joints with prosthetic components, maintaining wrist motion unlike arthrodesis which eliminates all motion.
Historical Context: Wrist arthroplasty has evolved through three generations. First-generation designs (1970s-1980s) had high failure rates due to poor fixation and excessive constraint. Second-generation designs (1980s-1990s) introduced improved fixation but still had significant loosening. Third-generation designs (2000s-present) including Universal 2, Maestro, and ReMotion use ellipsoidal articulation, improved distal fixation, and better bone preservation with improved but still concerning long-term survival.
Current Indications:
Primary Indication (Ideal Candidate):
- Rheumatoid arthritis with low functional demands
- Bilateral wrist disease (motion preservation both sides)
- Contralateral wrist fusion (motion preservation essential)
- Elderly patients with limited activity expectations
Secondary Indications:
- Primary osteoarthritis in low-demand patients
- Post-traumatic arthritis in carefully selected patients
- SLAC/SNAC wrist when motion preservation desired
Relative Contraindications:
- High-demand patients or heavy manual labor
- Young age with longevity concerns
- Poor bone stock (severe osteopenia)
- Inadequate soft tissue envelope or extensor deficiency
- Active infection
Epidemiology:
- Frequency: Uncommon compared to fusion (approximately 1:10 ratio)
- Trend: Increasing use due to improved third-generation designs
- Registry data: AOANJRR limited data due to low numbers
Why TWA Remains Niche
Despite motion preservation, TWA remains a niche procedure because durability is inferior to fusion. Distal component loosening at 10-30% is concerning compared to 5-10% nonunion for fusion. Patient selection is critical - RA with low demands is ideal. High-demand patients should have fusion. The trade-off is motion versus durability.
Implant Types and Biomechanics
Evolution of Wrist Arthroplasty Designs:
First Generation (1970s-1980s):
- Silicone spacers (Swanson)
- Ball-and-socket designs (Meuli)
- High failure rates due to silicone synovitis, constraint, loosening
- Largely abandoned
Second Generation (1980s-1990s):
- Biaxial design (Cooney)
- Improved fixation but still significant loosening
- Constrained designs caused bone loss
Third Generation (Current):
Universal 2 (Integra)
Design Features:
- Ellipsoidal articulation (toroidal radial component)
- Titanium porous-coated radial component
- Cobalt-chrome carpal component
- Polyethylene insert (UHMWPE)
- Distal fixation into 2nd and 3rd metacarpals
Fixation:
- Proximal: Press-fit or cemented into radius
- Distal: Carpal plate with metacarpal stems
Motion:
- Flexion-extension: 40-60 degrees arc
- Radial-ulnar deviation: 15-25 degrees arc
Outcomes:
- 80-85% survival at 5 years
- 60-70% survival at 10 years
Most widely used design with longest follow-up data.
Surgical Technique
Pre-operative Planning Steps
1. Patient Selection:
- Confirm low-demand lifestyle
- Assess functional requirements
- Evaluate bilateral disease status
- Discuss expectations and limitations
2. Disease Assessment:
- Confirm end-stage arthritis
- Assess bone quality (RA often osteopenic)
- Evaluate soft tissue envelope
- Assess extensor tendon integrity
3. Imaging:
- PA and lateral wrist X-rays
- Templating for component sizing
- CT if bone stock concerns
- MRI if soft tissue concerns
4. Equipment:
- TWA system (Universal 2, Maestro, or ReMotion)
- Multiple sizes available
- Cement if needed (RA with soft bone)
- Fluoroscopy for intraoperative imaging
5. Consent Discussion:
- Motion preservation benefit versus durability concerns
- Revision rate higher than fusion
- Activity restrictions permanent
- Alternative of fusion discussed
Proper planning ensures appropriate patient selection and realistic expectations.
Complications
Complications of Total Wrist Arthroplasty
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Distal component loosening | 10-30% | High demand, poor bone quality, malalignment | Revision arthroplasty or conversion to fusion |
| Impingement | 10-15% | Component malposition, inadequate resection | Debridement, component revision if severe |
| Extensor tendon rupture | 5-10% | Dorsal hardware prominence, RA (weakened tendons) | Tendon reconstruction or transfer |
| Instability and dislocation | 5-10% | Soft tissue deficiency, component malalignment | Thicker polyethylene, ligament repair, revision |
| Periprosthetic fracture | 3-5% | Osteopenic bone, trauma, stress risers | ORIF if stable, revision if loose |
| Infection | 2-5% | RA (immunosuppression), diabetes, poor nutrition | Debridement, antibiotics, may need explant |
| Nerve injury | 5-10% | Superficial radial nerve at risk dorsally | Usually neuropraxia - observe, neuroma excision if persistent |
Distal Component Loosening - The Key Failure Mode
Distal component loosening is the Achilles heel of wrist arthroplasty, occurring in 10-30% of cases. It occurs at the carpal-metacarpal junction due to stress concentration, inadequate fixation, and stress shielding. Third-generation designs address this with improved metacarpal stems or central screw fixation, but long-term durability remains inferior to fusion. Patient selection (low demand) is critical for minimizing this complication.
Extensor Tendon Rupture
Extensor tendon rupture (5-10%) occurs due to dorsal hardware prominence and is more common in RA patients who have weakened tendons. Prevention includes ensuring smooth dorsal profile, adequate soft tissue coverage, and early hardware removal if prominent. Management requires tendon reconstruction or transfer (EIP to EPL for EPL rupture).
Postoperative Care and Rehabilitation
Immediate Postoperative Care (0-2 weeks)
Day of Surgery:
- Volar splint in neutral position
- Elevation above heart level
- Neurovascular checks every 4 hours
- Finger ROM encouraged immediately
Days 1-14:
- Maintain splint continuously
- Active finger ROM exercises
- Wound check at 7-10 days
- Suture removal at 10-14 days
- Convert to removable splint at 2 weeks
Pain Management:
- Multimodal analgesia (paracetamol, NSAIDs if appropriate)
- Opioids for breakthrough pain
- Ice elevation for swelling
Early finger motion maintains tendon gliding and prevents stiffness.
Evidence Base and Key Trials
Third-Generation TWA Outcomes
- Universal 2 arthroplasty: 80% survival at 5 years
- Mean arc of motion 45 degrees flexion-extension
- Distal component loosening in 15% at 5 years
- Pain relief achieved in 85% of patients
TWA vs Arthrodesis Systematic Review
- TWA preserves 40-60 degrees motion vs 0 for fusion
- Fusion has lower revision rate (5% vs 20%)
- Similar pain relief between procedures
- TWA better for bilateral disease due to motion preservation
ReMotion Wrist Arthroplasty Outcomes
- 92% survival at 5 years with ReMotion design
- Mean flexion-extension arc 55 degrees
- 5% revision rate at medium-term follow-up
- Improved motion compared to earlier designs
Rheumatoid Arthritis Outcomes in TWA
- RA patients show 82% survival at 8 years
- Low demand nature of RA patients improves outcomes
- Soft bone accepts cement well improving fixation
- Bilateral disease benefits from motion preservation
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: TWA vs Fusion Decision (3-4 min)
"A 62-year-old woman with bilateral rheumatoid arthritis affecting both wrists presents with end-stage disease. Her left wrist was fused 3 years ago and she now has progressive pain in her right wrist. She works as a retired librarian and has low physical demands. Discuss your management options and justify your recommendation."
Scenario 2: Distal Loosening Management (3-4 min)
"A 68-year-old man presents 4 years after total wrist arthroplasty with progressive wrist pain. X-rays show lucency around the distal component with subsidence. He has low demands and good bone stock. How do you manage this?"
Scenario 3: Extensor Tendon Rupture (2-3 min)
"A 70-year-old woman with RA presents 2 years after TWA with inability to extend her thumb. On examination she has loss of thumb IP extension. X-rays show well-fixed components. What is your diagnosis and management?"
Australian Context
Epidemiology in Australia: Wrist arthroplasty is performed in low numbers in Australia, with limited AOANJRR data available due to small case volumes. The procedure is primarily performed in tertiary hand surgery units by subspecialty-trained surgeons. Rheumatoid arthritis remains the primary indication, though the incidence of severe RA requiring surgical intervention has decreased with improved disease-modifying therapy.
Access and Resources: All major implant systems (Universal 2, Maestro, ReMotion) are TGA-approved and available in Australia. The procedure is performed in both public and private settings, with most cases concentrated in metropolitan hand surgery units. RA patients typically have good access to multidisciplinary rheumatology care, including biologic therapy through PBS, which may reduce the number requiring surgical intervention.
Training and Expertise: Wrist arthroplasty is a subspecialty procedure requiring specific training beyond standard orthopaedic fellowship. Australian hand surgery fellowship programs include exposure to TWA, and surgeons performing the procedure should have completed appropriate subspecialty training. The relatively low case volumes mean maintaining expertise requires ongoing commitment and potentially fellowship in high-volume international centers.
Wrist Arthroplasty Exam Quick Reference
High-Yield Exam Summary
Indications
- •Primary: RA with low demands (ideal candidate)
- •Bilateral disease - motion preservation both sides
- •Contralateral fusion - avoid bilateral fusion
- •Elderly with limited activity expectations
Contraindications
- •High-demand or manual labor - choose fusion
- •Young age - durability concerns
- •Poor bone stock - inadequate fixation
- •Active infection - eradicate first
Key Numbers
- •Motion: 40-60 degree arc preserved
- •5-year survival: 80%
- •Distal loosening: 10-30%
- •Revision rate: 15-25% at 10 years
Implant Types
- •Universal 2 - most widely used, longest follow-up
- •Maestro - bone-preserving, easier revision
- •ReMotion - newest, anatomic design
- •All third-generation ellipsoidal articulation
Complications
- •Distal loosening - KEY failure mode (10-30%)
- •Extensor tendon rupture (5-10%) - dorsal hardware
- •Impingement (10-15%)
- •Revision to fusion if failed
TWA vs Fusion
- •TWA: motion preserved but less durable
- •Fusion: no motion but 95% union
- •Fusion revision rate 5-10% vs TWA 15-25%
- •Fusion gold standard for high-demand
References
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Cooney WP, et al. Total wrist arthroplasty: A review of recent experience. J Hand Surg Am. 2012;37(2):358-367.
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Cavaliere CM, Chung KC. A systematic review of total wrist arthroplasty compared with total wrist arthrodesis for rheumatoid arthritis. Plast Reconstr Surg. 2008;122(3):813-825.
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Krukhaug Y, et al. A randomized clinical trial comparing Maestro and Universal 2 total wrist arthroplasty. J Hand Surg Eur. 2011;36(3):218-226.
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Ferreres A, et al. Long-term follow-up of total wrist arthroplasty for rheumatoid arthritis. J Hand Surg Eur. 2011;36(9):754-760.
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Weiss AP, et al. Total wrist arthroplasty. J Bone Joint Surg Am. 2013;95(15):1401-1407.
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Adams BD. Wrist arthroplasty: Partial and total. Hand Clin. 2013;29(1):79-89.
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Nydick JA, et al. Total wrist arthroplasty. J Hand Surg Am. 2012;37(8):1693-1702.
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Murphy DM, et al. Long-term results of Universal 2 total wrist arthroplasty. J Hand Surg Am. 2018;43(7):613-619.
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Ward CM, et al. Outcomes of total wrist arthroplasty: An analysis of implant-specific survival. J Hand Surg Am. 2018;43(8):719-726.
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Berber O, et al. Total wrist arthroplasty: A systematic review of outcomes and complications. J Hand Surg Eur. 2019;44(4):381-390.