Wrist Implant Arthroplasty

1. High-Yield Summary

• Primary Clinical Indication: Severe, disabling radiocarpal and midcarpal destruction secondary to rheumatoid arthritis, post-traumatic osteoarthritis, or advanced primary pan-carpal arthrosis in low-to-moderate physical demand patients seeking motion preservation over complete arthrodesis.
• The Critical Move: Precise anatomic alignment and trajectory of the distal carpal component along the longitudinal axis of the third metacarpal, coupled with meticulous soft-tissue balancing to avoid eccentric edge loading and prosthetic subluxation.
• Catastrophic Error to Avoid: Dorsal tilt or eccentric cortical perforation during carpal and metacarpal preparation, leading to early distal component loosening, dorsal carpal impingement, or extensor tendon attrition and rupture.
• Fundamental Surgical Philosophy: Total wrist arthroplasty (TWA) is an unconstrained or semi-constrained joint reconstruction that relies on an intact, balanced soft-tissue sleeve and adequate distal carpal bone stock to maintain stability; it provides functional pain relief with motion preservation but requires permanent post-surgical load restrictions.

2. Relevant Anatomy & Biomechanics

The wrist is a complex multi-articulated polycentric joint comprising the radiocarpal and midcarpal articulations, transferring loads from the hand to the forearm while providing a wide functional arc in sagittal, coronal, and oblique planes.

Osteology & Articular Geometry

The radiocarpal joint is formed by the biconcave distal articular surface of the radius (scaphoid and lunate fossae) and the triangular fibrocartilage complex (TFCC) articulating with the convex proximal carpal row (scaphoid, lunate, and triquetrum). The midcarpal joint separates the proximal row from the distal row (trapezium, trapezoid, capitate, and hamate), which acts as a rigid biomechanical unit anchored by strong intercarpal ligaments.

Kinematic Axis & The “Dart Thrower’s Motion”

Normal wrist kinematics rotate about an instantaneous center of rotation located within the proximal head of the capitate. Functional upper extremity tasks rarely occur in pure flexion-extension or pure radioulnar deviation; instead, most daily activities utilize the “dart thrower’s motion” (DTM) plane, extending from radial extension to ulnar flexion. In modern third- and fourth-generation total wrist arthroplasties (such as ellipsoidal resurfacing or semi-constrained ball-and-socket configurations), aligning the prosthetic center of rotation with the anatomic capitate center restores this natural motion arc while minimizing destructive shear forces transmitted to the bone-implant interface.

Dorsal Extensor Retinaculum & Compartments

The dorsal wrist is organized into six discrete fibro-osseous compartments beneath the extensor retinaculum:

• 1st Compartment: Abductor pollicis longus (APL) and extensor pollicis brevis (EPB).
• 2nd Compartment: Extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB) — primary wrist motors.
• 3rd Compartment: Extensor pollicis longus (EPL), coursing obliquely around Lister’s tubercle.
• 4th Compartment: Extensor digitorum communis (EDC) and extensor indicis proprius (EIP), alongside the terminal sensory branch of the posterior interosseous nerve (PIN).
• 5th Compartment: Extensor digiti minimi (EDM).
• 6th Compartment: Extensor carpi ulnaris (ECU).

Neurovascular Danger Zones

Superficial sensory nerves cross the operative corridor and are vulnerable during initial surgical exposure:

• Superficial Branch of the Radial Nerve (SBRN): Emerges beneath the brachioradialis tendon approximately 5 cm proximal to the radial styloid, arborizing over the dorsoradial wrist. Traction or laceration causes recalcitrant painful neuromas.
• Dorsal Cutaneous Branch of the Ulnar Nerve (DCBUN): Branches from the ulnar nerve 5 to 7 cm proximal to the ulnar head, passing obliquely dorsally across the fifth and sixth extensor compartments.
• Median Nerve: Located on the volar side of the wrist within the carpal tunnel, directly anterior to the fibrous floor of the deep carpal capsule. Unchecked anterior saw excursion or excessive anterior screw penetration poses a direct risk of median nerve injury.
• Terminal Posterior Interosseous Nerve (PIN): Located on the dorsal periosteum of the distal radius on the floor of the fourth compartment; formal excision is therapeutic for denervation.

3. Indications & Contraindications

Patient selection is the primary determinant of long-term survivorship in wrist implant arthroplasty. The ideal candidate prioritizes preserved motion for low-load daily tasks over the heavy load-bearing capacity of total wrist arthrodesis.

Absolute Indications

• Severe, debilitating pain and joint destruction from inflammatory arthritis (rheumatoid arthritis, psoriatic arthritis, lupus arthropathy) refractory to medical optimization and conservative measures.
• Advanced post-traumatic osteoarthritis (scapholunate advanced collapse [SLAC] stage III, scaphoid nonunion advanced collapse [SNAC] stage III) or primary pancarpal osteoarthritis in low-to-moderate demand elderly patients.
• Failed motion-preserving partial carpal fusions or proximal row carpectomy (PRC) with secondary radiocapitate arthritis.

Relative Indications

• Bilateral severe wrist arthritis: performing total wrist arthroplasty on the dominant or more functional side while reserving total wrist arthrodesis for the contralateral high-load bearing side.
• Concurrent severe upper extremity arthropathy (severe ipsilateral shoulder, elbow, or metacarpophalangeal disease) where wrist motion is critical to place the hand in functional space for personal hygiene, eating, and perineal care.

Contraindications

Decision Matrix: Total Wrist Arthroplasty vs Total Wrist Arthrodesis

4. Preoperative Planning

Imaging Review & Radiographic Metrics

Preoperative radiographic assessment requires standardized, non-magnified views and volumetric cross-sectional imaging:

• Standard Radiographs: Posteroanterior (PA), lateral, and 45° semipronated oblique views of the wrist, along with full-length forearm views to evaluate mechanical axis alignment and prior deformities.
• Carpal Height Ratio (Youm’s Ratio): Ratio of carpal height (distance between the distal radial articular surface and the base of the third metacarpal) to the length of the third metacarpal (normal: 0.54 ± 0.03). Significant carpal collapse (<0.40) flags extensive osteolysis and potential difficulty securing distal components.
• Computed Tomography (CT) with 3D Reconstruction: Highly recommended to evaluate residual bone stock in the capitate, hamate, and distal radius. Sizing templates are overlaid onto axial and coronal CT cuts to confirm that the central carpal peg and peripheral locking screws will purchase bicortical bone without dorsal or volar wall blowout.
• Distal Radioulnar Joint (DRUJ) Evaluation: Arthritic destruction or instability of the DRUJ must be assessed. If symptomatic, an adjunct procedure (Sauvé-Kapandji, Darrach resection, or hemi-arthroplasty) must be incorporated into the surgical plan.

Examination Under Anesthesia (EUA)

Following general or regional anesthesia and prior to limb exsanguination, a focused physical examination under anesthesia is performed:

• Passive Arc of Motion: Document baseline passive flexion, extension, pronation, supination, and radial/ulnar deviation.
• Joint Reducibility: Assess whether fixed carpal subluxation can be manually reduced into the neutral anatomic axis under gentle longitudinal traction.
• DRUJ Stability: Perform the piano key test and assess passive ballottement of the distal ulna relative to the radius.
• Extensor & Flexor Motor Integrity: Perform passive tenodesis testing of the fingers and wrist to confirm functional tendon excursion.

Equipment Checklist

• Modular Total Wrist Arthroplasty Instrument & Implant System (e.g., Re-Motion, Maestro, or Motec) with complete inventory of radial stems, carpal plates, central fixation pegs, locking/cancellous screws, and UHMWPE bearing inserts.
• High-resolution mini C-arm or standard fluoroscopy unit.
• Pneumatic tourniquet with sterile arm sleeve.
• Oscillating sagittal saw with micro-thin blades (0.4–0.6 mm) and cold saline irrigation.
• High-speed pencil burr and small fine osteotomes (2 mm, 4 mm, 6 mm).
• Small bone curettes, rongeurs, and fine multi-prong retractors (Senn, Ragnell, mini Hohmann).
• Non-absorbable braided sutures (No. 0 and 2-0 FiberWire or Ethibond) for robust capsular repair.
• Autologous bone graft harvesting equipment or mineralized cancellous allograft for void packing.

5. Patient Positioning & Setup

Precise patient positioning provides unhindered circumferential visualization of the wrist and uninterrupted fluoroscopic imaging throughout the critical preparation phases.

Operating Room Setup

• Patient Orientation: The patient is positioned supine on the operating table. The operative extremity is placed onto a radiolucent hand table extension.
• Tourniquet Placement: A well-padded pneumatic tourniquet is applied to the upper arm. The limb is elevated and exsanguinated with an Esmarch bandage before inflating the tourniquet to 250 mmHg.
• Lead Hand / Fixation: A malleable lead hand or specialized digit traps can be used during initial soft-tissue exposure, then removed during trialing to permit unhindered dynamic range-of-motion assessments.

Safety Check & Fluoroscopy Corridors

• Prior to sterile preparation, verify that the fluoroscopic C-arm can transition seamlessly between true PA and lateral views without colliding with the hand table, anesthesia tubing, or surgeon’s arm rests.
• Ensure the contralateral side and head of the bed remain clear to allow the C-arm base to maneuver into position.

6. Surgical Approach

A direct dorsal midline approach centered over the radiocarpal joint provides safe, expansile access to the distal radius, carpus, and extensor compartments.

Skin Incision

A straight 8 to 10 cm dorsal longitudinal incision is marked in line with the third metacarpal shaft, crossing the radiocarpal joint immediately ulnar to Lister’s tubercle and extending proximally over the midline of the distal radius. Gentle longitudinal curves can be employed across the wrist crease to prevent hypertrophic contracture.

Superficial Dissection & Internervous Plane

Full-thickness skin and subcutaneous flaps are elevated directly off the shiny white extensor retinaculum. Thin cutaneous flaps must be avoided to eliminate the risk of dorsal skin edge necrosis. The superficial branch of the radial nerve is identified and protected in the radial flap, and the dorsal cutaneous branch of the ulnar nerve is preserved in the ulnar flap.

The operative plane is developed between the second extensor compartment (ECRL/ECRB, innervated by the radial nerve proper) and the fourth extensor compartment (EDC/EIP, innervated by the posterior interosseous nerve), establishing a safe anatomical internervous interval.

Retinacular Flap Elevation & PIN Neurectomy

• The third extensor compartment is opened longitudinally along the course of the EPL tendon. The EPL is mobilized completely from its groove around Lister’s tubercle and transposed radially.
• An extensor retinacular flap is elevated, either based radially or ulnarly, exposing the second, fourth, and fifth compartments while keeping the extensor tendons protected within their sheaths.
• Terminal PIN Neurectomy: The terminal branch of the posterior interosseous nerve is identified on the floor of the fourth compartment resting directly on the periosteum of the dorsal distal radius. A 1.5 to 2.0 cm segment of the nerve is resected, and the proximal stump is allowed to retract into the deep pronator quadratus substance to provide partial wrist denervation and reduce postoperative pain.

Dorsal Capsulotomy

A ligament-sparing, distally or radially based inverted-T or H-shaped capsulotomy is performed. Subperiosteal dissection elevates the capsule cleanly off the distal radius and proximal carpal bones, leaving a generous 2 to 3 mm fringe of capsular tissue attached proximally and distally for watertight closure during wound closure.

7. Step-by-Step Surgical Technique

The operative technique is executed in five precise, interdependent stages to ensure stable implant seating and balanced kinematics.

Step 1: Carpal Row Resection and Joint Mobilization

Expose the radiocarpal and midcarpal joints using fine mini Hohmann retractors placed subperiosteally along the radial and ulnar borders. Excise the diseased proximal carpal row bones according to the implant design specifications. In modern modular systems (such as Re-Motion), the scaphoid is excised in its entirety or its distal pole is preserved, the triquetrum is excised or trimmed, and the lunate is completely removed to expose the proximal articular pole of the capitate.

Step 2: Distal Radial Resection and Intramedullary Preparation

• Position the distal radial resection cutting jig. Align the guide referencing the intramedullary longitudinal axis of the radius under fluoroscopic guidance, establishing a cut perpendicular to the long axis in the sagittal plane with neutral or 0°–3° of anatomic volar inclination.
• Perform the distal radial osteotomy using an oscillating sagittal saw with continuous cold irrigation. Make a conservative cut, removing typically 2 to 4 mm of subchondral bone from the scaphoid/lunate fossae, taking strict care to preserve the sigmoid notch and the deep attachments of the triangular fibrocartilage complex.
• Broach the radial intramedullary canal sequentially, sizing up until axial and rotational cortical stability is achieved without cortical expansion or fissuring.

Step 3: Distal Carpal Preparation and Metacarpal Canal Broaching

• Decorticate the proximal articular surface of the capitate and adjacent intercarpal joints (capitate-hamate, capitate-trapezoid) to create a bleeding flat bone bed that will integrate with the porous carpal plate.
• Mount the carpal guide aligned strictly with the longitudinal anatomical axis of the third metacarpal shaft under biplanar fluoroscopy. Avoid dorsal or volar trajectory error.
• Drill and broach the central peg corridor through the capitate and into the intramedullary canal of the third metacarpal base.
• Prepare pilot holes for peripheral fixation screws directed into the body of the hamate ulnarly and the trapezoid/trapezium complex radially to establish multi-point carpal fixation.

Step 4: Trial Reduction, Kinematic Balancing & Sizing

• Insert the radial stem trial, carpal component trial, and a nominal trial polyethylene bearing insert.
• Reduce the wrist articulation under gentle longitudinal traction.
• Evaluate the motion envelope: target 35°–40° of passive extension, 30°–35° of passive flexion, and 10°–15° of radial and ulnar deviation.
• Assess stability under dynamic stress: apply passive axial load and verify concentric tracking through the full motion arc without component lift-off, dorsal subluxation, or impingement. If tight in extension, resect an additional 1–2 mm of distal radius or select a thinner bearing insert; if lax, increase polyethylene insert thickness.

Step 5: Final Component Implantation & Closure

• Irrigate the osseous surfaces copiously with pulsed lavage to remove all bone dust and debris.
• Impact the definitive press-fit porous-coated radial component into the radial intramedullary canal until fully seated on the osteotomy resection floor.
• Seat the definitive carpal component onto the prepared carpal bed, driving the central peg into the third metacarpal and placing locking/cancellous screws into the hamate and trapezoid. Pack morselized autologous bone graft harvested from the carpal bones around the plate to promote fusion of the carpal unit.
• Engage the definitive UHMWPE bearing component, locking it firmly into place with the locking mechanism. Verify final positioning under true PA and lateral fluoroscopy.
• Repair the dorsal capsule securely using non-absorbable braided sutures to reconstruct dorsal stability and prevent dorsal migration.
• Transpose the EPL tendon superficial to the repaired extensor retinaculum to eliminate mechanical friction. Close the skin in layers over a small closed-suction drain if indicated.

8. Intraoperative Balance & Critical Moves

The margin for error in total wrist arthroplasty is narrow. Operating surgeons must adhere to strict tactile and visual checkpoints during irreversible steps.

Point of No Return: Metacarpal Canal Trajectory

The single most catastrophic technical error is entering the third metacarpal canal with excessive dorsal or volar inclination. A dorsal trajectory can penetrate the dorsal cortex, causing extensor tendon irritation or failure of distal fixation; a volar trajectory risks carpal tunnel penetration and median nerve injury. Always verify drill and broach trajectory on a true lateral fluoroscopic view before advancing beyond the proximal subchondral plate.

The Soft-Tissue Balance Checkpoint

Over-stuffing the joint (implanting an overly thick polyethylene insert) leads to excessive extensor tension, severe stiffness, and accelerated polyethylene wear. Conversely, under-tensioning leads to prosthetic instability and recurrent subluxation. With trial components in place, releasing traction should allow the components to maintain concentric contact with passive wrist stability, while 2 to 3 mm of manual distraction (“shuck”) can be elicited under longitudinal pull.

9. Pearls and Pitfalls

10. Postoperative Care & Rehabilitation

A supervised, structured postoperative hand therapy protocol is essential to protect soft-tissue healing while gradually developing a functional, stable arc of motion.

Immediate Postoperative Management

• Immobilization: A bulky, well-padded sterile dressing and rigid volar plaster splint supporting the wrist in 15°–20° of dorsiflexion and neutral deviation.
• Early Mobilization: Immediate active and active-assisted range of motion for all digits (MCP, PIP, DIP joints), thumb opposition, and full elbow/shoulder mobility to prevent stiffness and edema.
• Elevation: Strict limb elevation above heart level for the first 48 to 72 hours.

Phase-by-Phase Rehabilitation Protocol

• Phase I: Protection & Edema Control (Weeks 0–2): Strict splint immobilization. Suture removal at 10–14 days. Continuous active digital motion and composite fist formation.
• Phase II: Motion Initiation (Weeks 2–6): Transition from plaster splint to a custom-molded removable thermoplastic wrist orthosis worn between exercise sessions and at night. Initiate active and active-assisted wrist extension, flexion, and gentle forearm pronation/supination. Strict non-weight-bearing (NWB) status. No passive stretching or forced manipulation.
• Phase III: Functional Progression (Weeks 6–12): Wean from splint during daytime light activities. Initiate gentle isometric wrist strengthening and progressive resistance therapy with putty and light elastic bands. Continue night splinting until 8–10 weeks.
• Phase IV: Long-Term Maintenance (>12 Weeks): Discontinue daytime splint. Emphasize endurance and coordination. Transition to lifelong activity modifications: strict lifting limit of 5–10 lbs (2.5–5.0 kg), complete avoidance of repetitive impact activities (hammering, contact sports, golf), and avoidance of heavy push-up activities on an extended wrist.

11. Outcomes & Implant Survivorship

Modern total wrist arthroplasty provides predictable, lasting pain relief and functional motion retention, though long-term survivorship remains inferior to hip and knee arthroplasties.

Functional Motion & Patient-Reported Metrics

• Motion Arc: Modern series consistently demonstrate a functional preserved arc of motion averaging 30°–35° extension, 25°–30° flexion, 10°–15° radial deviation, and 15°–20° ulnar deviation, meeting the Palmer criteria (30° extension, 5° flexion, 10° radial deviation, 15° ulnar deviation) for normal activities of daily living.
• Pain Relief: Complete or substantial pain relief is achieved in 85% to 92% of patients at midterm follow-up.
• Validated Scores: Significant improvements are documented across DASH (Disabilities of the Arm, Shoulder and Hand), PRWE (Patient-Rated Wrist Evaluation), and Mayo Wrist scores.

Implant Survivorship & Generations

• 1st Generation (Silicone Spacers – Swanson): High early failure rates due to silicone synovitis, particulate lymphadenopathy, implant fracture, and progressive carpal collapse.
• 2nd Generation (Volz, Meuli): Constrained and semi-constrained designs; suffered high rates of distal component loosening from uncompensated torque forces.
• 3rd and 4th Generation (Biaxial, Universal 2, Re-Motion, Maestro, Motec): Unconstrained or modular semi-constrained designs with titanium/cobalt-chrome porous coating, locking screw carpal fixation, and anatomical center of rotation. Five-year survivorship ranges from 90% to 95%, and ten-year cumulative survivorship ranges from 75% to 85% in rheumatoid arthritis cohorts. In non-rheumatoid, high-demand cohorts, 10-year survivorship drops to 65% to 75% due to higher mechanical demand and aseptic loosening.

12. Complications & Revision Strategies

Complications in wrist arthroplasty are common and necessitate early detection, meticulous planning, and clear patient counseling.

Aseptic Loosening & Subsidence

Aseptic loosening represents the single most common cause of late revision (accounting for >50% of revisions). The distal carpal plate is substantially more prone to loosening than the radial stem due to limited carpal bone stock, high cantilever shear stresses, and nonunion of the intercarpal fusion bed. Early radiolucency around distal screws warrants serial radiographic surveillance.

Implant Dislocation & Coronal Imbalance

Imbalance between the radial and ulnar wrist motors or asymmetric bone resection can cause progressive coronal tilt, edge loading, and joint dislocation. Closed reduction is rarely stable; revision of the polyethylene insert, correction of carpal component orientation, and soft-tissue rebalancing are typically required.

Extensor Tendon Attrition & Rupture

Extensor tendon complications (most commonly EPL or EDC to the ring/middle fingers) occur due to mechanical abrasion against prominent dorsal hardware, screw tips, or incomplete retinacular coverage. Treatment involves hardware removal, burring of prominent bone edges, and tendon transfer (e.g., EIP to EPL or side-to-side suture to adjacent intact EDC tendons).

Periprosthetic Joint Infection (PJI)

PJI occurs in 1% to 3% of cases, with higher incidence in immunosuppressed rheumatoid arthritis patients. Acute infections (<4–6 weeks) can be managed with open debridement, antibiotics, and modular component retention (DAIR). Chronic infections require complete two-stage explantation, placement of an antibiotic-loaded cement spacer, 6 weeks of targeted intravenous antimicrobial therapy, and subsequent conversion to total wrist arthrodesis.

Revision Total Wrist Arthroplasty vs Conversion to Arthrodesis

When wrist arthroplasty fails, revision options include:

• Revision Arthroplasty: Viable only when adequate carpal and metacarpal bone stock remains, utilizing long-stem revision radial components and customized carpal plates with extensive cancellous grafting.
• Conversion to Total Wrist Arthrodesis (TWD): The gold-standard salvage procedure for failed total wrist arthroplasty. Explantation of all components leaves a substantial structural carpal bone defect (often 2–4 cm), necessitating structural bone grafting (autologous corticocancellous iliac crest or femoral head allograft) and rigid internal fixation using a dorsal spanning wrist fusion plate anchored from the radius to the third metacarpal shaft.

13. Evidence-Based Synthesis

Modern clinical decision-making is grounded in high-quality randomized controlled trials and prospective registry analyses, corroborated by seminal biomechanical and anatomical descriptions.

14. References

• Holm-Glad T, Røkkum M, Röhrl SM et al. A randomized controlled trial comparing two modern total wrist arthroplasties : improved function with stable implants, but high complication rates in non-rheumatoid wrists at two years. Bone Joint J. 2022. doi:10.1302/0301-620X.104B10.BJJ-2022-0201.R2 [Level I: Randomized Controlled Trial]
• Berber O, Garagnani L, Gidwani S. Systematic Review of Total Wrist Arthroplasty and Arthrodesis in Wrist Arthritis. J Wrist Surg. 2018. doi:10.1055/s-0038-1646956 [Level II: Systematic Review / Comparative Analysis]
• Boeckstyns ME. Wrist arthroplasty–a systematic review. Dan Med J. 2014. doi:PMID:24814740 [Level I: Systematic Review / Meta-Analysis]
• Fischer P, Sagerfors M, Jakobsson H et al. Total Wrist Arthroplasty: A 10-Year Follow-Up. J Hand Surg Am. 2020. doi:10.1016/j.jhsa.2020.02.006 [Level IV: Prospective Cohort Study]
• Cobb TK, Beckenbaugh RD. Biaxial total-wrist arthroplasty. J Hand Surg Am. 1996. doi:10.1016/S0363-5023(96)80309-1 [Level IV: Seminal Cohort Study]

15. Master Class Pro-Tip

“In total wrist arthroplasty, the long-term fate of the reconstruction is decided at the carpal plate. Never rely on the central metacarpal peg alone to provide stability. Take the extra five minutes to meticulously decorticate the capitate-hamate-trapezoid interfaces and pack them with dense cancellous autograft harvested from your radial resection. Furthermore, when placing your peripheral carpal screws, aim for divergent bicortical purchase into the dense body of the hamate and trapezoid, and verify under direct vision that the screw heads are seated completely sub-flush beneath the plate. Any dorsal prominence will saw through the overlying extensor tendons within twenty-four months.”

Master Class Surgical Pearl: Achieving Rigid Distal Carpal Integration and Preventing Extensor Tendon Attrition