Rheumatoid arthritis of the thumb

1. High-Yield Summary

• Functional Dominance of the Thumb: The thumb accounts for 40% to 50% of overall hand function. Rheumatoid involvement occurs in 60% to 70% of patients with rheumatoid arthritis, causing progressive destruction of the three-joint kinetic column and severely degrading key pinch, tip pinch, and power grasp.
• Tri-Articular Kinetic Chain Mechanics: The thumb operates as an intercalated kinetic chain across the carpometacarpal (CMC), metacarpophalangeal (MCP), and interphalangeal (IP) joints. Synovitis initiating at one joint induces primary capsuloligamentous failure, driving predictable reciprocal compensatory deformities at adjacent joints.
• Nalebuff Classification Dictates Reconstructive Strategy: Rheumatoid thumb deformities are classified into Nalebuff Types I through VI. Type I (Boutonniere deformity: primary MCP flexion with secondary IP hyperextension) is most prevalent (approximately 50%), followed by Type III (Swan-neck deformity: primary CMC subluxation and adduction with secondary MCP hyperextension, 25% to 30%). Reconstructive success requires treating the primary initiating joint.
• MCP Arthrodesis as the Reconstructive Bedrock: Metacarpophalangeal joint arthrodesis is the gold standard for painful, unstable, or fixed Type I deformities. Fusion in 10° to 15° of flexion, 5° of abduction, and 5° of pronation achieves over 95% union, abolishes pain, and restores stable lateral key pinch.
• The Keystone Diagnostic Rule: Never fuse the MCP joint without first evaluating and addressing the basal CMC joint. Performing an MCP arthrodesis in the presence of an unrecognized or untreated CMC adduction contracture permanently locks the thumb into the plane of the palm, obliterating prehensile grasp span.

2. Anatomy

Reconstruction of the rheumatoid thumb demands precise knowledge of the tri-articular skeletal column, dynamic intrinsic and extrinsic muscular stabilizers, and adjacent neurovascular structures vulnerable during operative exposure.

Bony Architecture and Critical Landmarks

The thumb ray comprises three mobile articulations supported by key osseous structures:

• Trapezium: A saddle-shaped carpal bone featuring a reciprocally concavo-convex articular surface for the first metacarpal base. Its palmar ridge forms the lateral boundary of the carpal tunnel, and its deep groove accommodates the flexor carpi radialis (FCR) tendon.
• First Metacarpal Base: Articulates with the trapezium. Key landmarks include the palmar beak (insertion of the anterior oblique ligament) and the radial-dorsal tubercle (insertion of the abductor pollicis longus [APL] tendon). Attenuation of the palmar beak ligament allows dorsoradial subluxation in Type III deformities.
• Metacarpophalangeal Joint and Sesamoids: A condylar articulation with limited intrinsic bony stability, relying on collateral ligaments, the dorsal extensor hood, and the palmar plate. Two consistent sesamoid bones reside within the palmar plate: the radial sesamoid (receiving insertions of the flexor pollicis brevis [FPB] and abductor pollicis brevis [APB]) and the ulnar sesamoid (receiving the adductor pollicis [AdP]).
• Interphalangeal Joint: A true hinge articulation stabilized by robust collateral ligaments and the palmar plate, providing an insertion for the extensor pollicis longus (EPL) dorsally and the flexor pollicis longus (FPL) palmarward.

Neurovascular Danger Zones

Surgical dissections of the first ray are bounded by high-risk neurovascular corridors:

• Superficial Branch of the Radial Nerve (SBRN): Emerges beneath the brachioradialis tendon approximately 5 to 7 cm proximal to the radial styloid, piercing the antebrachial fascia to arborize into 3 to 5 terminal sensory branches across the anatomical snuffbox and dorsal thumb. Traction, aggressive retractor placement, or accidental transection produces debilitating, recalcitrant terminal neuromas and hypersensitivity. Full subcutaneous mobilization with gentle vessel loops is mandatory during dorsal exposures.
• Radial Digital Nerve and Artery: Arise from the median nerve and superficial palmar arch, traveling along the palmar-radial aspect of the first MCP joint immediately superficial to the radial sesamoid and thenar musculature. This neurovascular bundle is directly vulnerable during radial-sided MCP arthrotomies, radial collateral ligament repair, or distal extensions of the Wagner approach.
• Radial Artery (Snuffbox Floor) and Princeps Pollicis Artery: The radial artery winds through the floor of the anatomical snuffbox over the scaphoid and trapezium before diving deep between the two heads of the first dorsal interosseous muscle. There, it gives off the princeps pollicis artery, which runs along the palmar aspect of the first metacarpal. Inadvertent thermal injury during capsular release or bone resection risks thumb devascularization in patients with compromised digital perfusion.

Internervous Planes and Surgical Corridors

Safe surgical entry into the thumb relies on two established anatomic corridors:

• Wagner Approach to the Basal CMC Joint: A curvilinear incision placed along the glabrous-nonglabrous skin border over the radial aspect of the first metacarpal shaft, curving proximally over the trapeziometacarpal joint toward the FCR tendon. The true internervous plane lies between muscles innervated by the radial nerve (APL and extensor pollicis brevis [EPB]) dorsally and the median nerve (APB) palmarward. Subperiosteal elevation of the APB origin off the first metacarpal grants wide access to the anterior and lateral CMC joint capsule without denervating intrinsic muscles.
• Dorsal Approach to the MCP Joint: A straight longitudinal or gentle lazy-S incision centered over the MCP joint. Dissection remains deep to the arborizing branches of the SBRN. The deep exposure splits the extensor apparatus between the EPL and EPB or transposes the EPL tendon, exposing the dorsal joint capsule for synovectomy or arthrodesis.

3. Pathogenesis

The pathomechanics of rheumatoid thumb collapse originate from inflammatory synovial pannus, progressing through progressive soft-tissue attenuation, tendon subluxation, and secondary multi-joint biomechanical failure.

Synovial Pannus and Capsuloligamentous Attenuation

Hypertrophic, proliferative synovial pannus secretes aggressive matrix metalloproteinases (MMP-1, MMP-13), aggrecanases, and pro-inflammatory cytokines (TNF-alpha, IL-1beta, IL-6). This enzymatic cascade breaks down the proteoglycan matrix of articular cartilage and erodes cortical bone at periarticular bare areas. Concurrently, chronic intracapsular swelling mechanically distends the fibrous joint capsule, stretching collateral ligaments and destabilizing the dynamic tendon hood mechanism.

Kinetic Tri-Articular Chain Mechanics

Because the thumb is a multi-articulated open kinetic column, stability requires continuous equilibrium between extrinsic flexor/extensor units and intrinsic thenar muscles. Structural failure at one joint triggers an obligatory reciprocal collapse at adjacent joints:

• Type I (Boutonniere) Pathomechanics: Primary synovitis distends the MCP joint capsule, stretching and attenuating the EPB insertion at the base of the proximal phalanx. The extensor hood expands, allowing the EPL tendon and the intrinsic lateral bands (APB and AdP) to displace palmarward and laterally below the transverse axis of MCP flexion. Consequently, the EPL and intrinsic bands convert into dynamic flexors of the MCP joint. The increased pull of these subluxated lateral bands transmits excessive extensor force to the terminal EPL insertion on the distal phalanx, creating secondary compensatory IP joint hyperextension.
• Type III (Swan-Neck) Pathomechanics: Primary synovitis begins at the trapeziometacarpal (CMC) joint. Destruction of the anterior oblique (beak) ligament and dorsal capsule permits the first metacarpal base to subluxate dorsally and radially off the saddle of the trapezium. The metacarpal shaft collapses into adduction under the unopposed pull of the adductor pollicis. To achieve pinch grasp against this adducted metacarpal, the patient compensatory hyperextends the MCP joint. Over time, chronic hyperextension attenuates the palmar plate of the MCP joint. With the MCP joint locked in hyperextension, the FPL tendon is placed under passive tension, driving the IP joint into secondary flexion.

Attrition Tendon Ruptures

Tendon failure in rheumatoid arthritis can occur through direct inflammatory invasion or mechanical attrition over sharp bony spurs:

• Mannerfelt Syndrome (FPL Rupture): Proliferative synovitis within the carpal tunnel erodes the floor of the canal, uncovering sharp osteophytes on the scaphoid tubercle or trapezium. Repetitive gliding causes fraying and attritional rupture of the FPL tendon, manifesting as an acute, painless loss of active thumb IP flexion.
• EPL Attritional Rupture: Tenosynovitis within the third extensor compartment subjects the EPL tendon to local vascular ischemia and friction over the sharp bony margins of Lister tubercle, culminating in sudden rupture and loss of active thumb retropulsion and MCP extension.

4. Natural History

Rheumatoid arthritis affects approximately 0.5% to 1% of the global adult population, with a female-to-male ratio of 3:1. Progressive thumb involvement develops in 60% to 70% of patients with long-standing disease.

Functional Impact and Prehensile Deficits

The natural progression of the untreated rheumatoid thumb leads to profound functional disability. Normal hand function depends on a stable thumb column to generate key pinch (lateral pinch), tip-to-tip pinch, and cylindrical grasp. Progressive deformity leads to:

• Loss of Key and Tip Pinch: Lateral pinch strength drops from normal baseline values (6 to 10 kg) down to less than 1 to 2 kg or becomes completely unrecordable due to joint instability and pain.
• Narrowing of the First Web Space: Persistent metacarpal adduction contractures narrow the first web space, eliminating the ability to grasp large objects such as cups, jars, or door handles.
• Evolution from Flexible to Rigid Deformity: Deformities initially present in an early, flexible stage where passive correction is achievable. Without effective medical or surgical management, persistent subluxation leads to full-thickness chondral loss, joint contracture, periarticular osteopenia, and rigid, fixed articular dislocation.
• Terminal Telescoping (Arthritis Mutilans): In the most destructive phenotype (Nalebuff Type VI), unchecked osteoclastic resorption dissolves the metacarpal and phalangeal bone ends, resulting in a flail, shortened, telescoping thumb (“opera-glass hand”).

5. Clinical Presentation

A rigorous clinical evaluation identifies the primary site of joint destruction, distinguishes reducible soft-tissue imbalances from fixed articular contractures, and screens for concurrent tendon ruptures.

History

Clinical inquiry must delineate disease chronicity, pharmacotherapy, and specific prehensile limitations:

• Symptom Onset and Chronicity: Determine the duration of joint pain, swelling, and progressive deformity. Inquire whether deformity progression was gradual or whether a sudden loss of motion occurred.
• Functional Impairment: Document specific limitations in activities of daily living: manipulating keys, turning doorknobs, fastening buttons, holding writing utensils, or opening jars.
• Sudden Mechanical Failures: Inquire about sudden loss of thumb IP flexion (indicative of Mannerfelt syndrome) or sudden inability to lift the thumb off a flat surface (indicative of EPL rupture).
• Systemic Medical Regimen: Review current disease-modifying antirheumatic drugs (DMARDs), biologic agents (TNF inhibitors, IL-6 receptor antagonists), and chronic systemic corticosteroid exposure, which influence infection risk, soft-tissue quality, and bone mineral density.

Physical Examination

Examination begins with visual inspection of the resting posture, evaluating the first web space aperture, localized synovial fullness, and joint alignment. Each joint in the column must be individually assessed for active range of motion, passive reducibility, and angular stability.

6. Imaging and Diagnostic Studies

Diagnostic imaging defines the extent of articular cartilage destruction, periarticular erosions, bone stock availability, and dynamic tendon integrity across the column.

Plain Radiography and Specialty Projections

Standard radiographic assessment requires a minimum of three views supplemented by dedicated specialty projections:

• Standard Series: Posteroanterior (PA), lateral, and pronated oblique views of the hand and thumb.
• Robert View (True AP of the CMC Joint): Obtained with the forearm in maximal hyperpronation, placing the dorsum of the thumb flat against the radiographic cassette with the beam directed perpendicular to the first CMC joint. This view eliminates bony overlap, providing an unobscured profile of the trapeziometacarpal joint space, osteophytes, and subluxation.
• Stress Views: Bilateral key pinch views or manual valgus/varus stress views demonstrate dynamic collateral ligament incompetence and occult subluxations.

Radiographic Hallmarks and Staging Criteria

Radiographs must be systematically reviewed for classic features of rheumatoid articular destruction:

• Larsen Articular Grading: Grade 0 (normal), Grade I (slight joint space narrowing and soft-tissue swelling), Grade II (early small erosions and definite joint space narrowing), Grade III (moderate erosions and joint destruction), Grade IV (severe erosions, marked joint loss), and Grade V (mutilating collapse, gross joint disappearance).
• Marginal Bony Erosions: Focal cortical disruptions occurring at capsular insertion “bare areas” devoid of protective articular cartilage.
• Subluxation Vectors: Palmar subluxation of the proximal phalanx on the metacarpal head in Type I deformities; dorsoradial subluxation of the first metacarpal base off the trapezium in Type III deformities.
• Acro-osteolysis and Resorption: In Type VI arthritis mutilans, extensive pencil-in-cup deformities and massive resorption of metacarpal and phalangeal shafts are evident.

Advanced Imaging: Ultrasound and MRI

Cross-sectional and dynamic imaging modalities serve specialized diagnostic roles:

• High-Resolution Musculoskeletal Ultrasound: Highly sensitive for detecting early synovial hypertrophy, synovial hypervascularity via Power Doppler signaling, and pre-radiographic cortical bone erosions. Ultrasound offers dynamic assessment of flexor and extensor tendon excursions, confirming tenosynovitis or occult partial-thickness tendon tears.
• Magnetic Resonance Imaging (MRI): Demonstrates inflammatory pannus volume, subchondral bone marrow edema (osteitis), and occult carpal collapse. Contrast-enhanced sequences distinguish active vascularized pannus from fibrous scar tissue and delineate deep flexor tendon attrition at the scaphoid tubercle.

7. Classification

The Nalebuff classification remains the clinical standard, categorizing rheumatoid thumb deformities into six distinct pathomechanical patterns based on the primary site of joint destruction and secondary compensatory adaptations.

8. Treatment

Management of rheumatoid thumb disease involves close coordination between medical rheumatologic control, custom orthotic stabilization, and staged surgical reconstruction.

Medical and Nonoperative Management

Modern pharmacotherapy and targeted functional splinting form the foundation of conservative care:

• Disease-Modifying Antirheumatic Therapy: Early initiation of conventional synthetic DMARDs (methotrexate, leflunomide) and escalation to biologic agents (TNF inhibitors such as adalimumab, etanercept; IL-6 receptor antagonists such as tocilizumab) or targeted synthetic JAK inhibitors halts systemic synovitis and slows articular cartilage degradation. However, pharmacotherapy cannot restore mechanical stability once ligaments have ruptured or bone stock is lost.
• Judicious Corticosteroid Injections: Intra-articular corticosteroid administration provides temporary symptomatic relief during acute inflammatory flares. Injections must be limited; repeated intra-articular steroid delivery accelerates cartilage breakdown and increases the risk of tendon rupture and local infection.
• Custom Thermoplastic Functional Orthoses: Custom-molded thermoplastic thumb spica or MCP-stabilizing orthoses provide static support during functional pinch tasks. High-level randomized controlled trial evidence demonstrates that consistent wear of functional orthoses over 90 days significantly improves lateral pinch strength, grip strength, and Cochin Hand Function scores without compromising passive joint range of motion.
• Occupational and Physical Therapy: Focuses on joint protection education, adaptive gripping equipment (ergonomic utensils, jar-opening devices), and gentle active-assisted range of motion to prevent joint contractures.

Operative Management

The primary objectives of operative intervention are to eliminate joint pain, establish a stable, rigid pillar for pinch grasp, correct fixed multi-planar deformities, and preserve motion at adjacent uninvolved joints.

Type-Specific Surgical Algorithms

• Type I (Boutonniere) Reconstruction:
  • Early Flexible Deformity: In patients with preserved joint space on radiographs and a passively correctable MCP joint, perform an open dorsal MCP synovectomy, reroute the EPL tendon back to the midline, and shorten/advance the EPB tendon insertion into the base of the proximal phalanx.
  • Late Fixed Deformity (Gold Standard): If articular cartilage is destroyed, fixed flexion contracture exceeds 30°, or collateral ligaments are incompetent, perform MCP Arthrodesis. Prepare bone surfaces with cup-and-cone reaming or planar coaptation cuts. Rigid internal fixation is achieved using crossed K-wires, tension-band wiring, or a low-profile plate. Arthrodesis position must be strictly set at 10° to 15° of flexion, 5° of abduction, and 5° of pronation. Following MCP fusion, compensatory IP hyperextension often resolves spontaneously; if rigid IP contracture persists, perform closed manipulation or open release.
• Type II (Boutonniere with Basal Subluxation) Reconstruction: Address both pathology sites. Perform an MCP arthrodesis combined with trapeziectomy and ligament reconstruction and tendon interposition (LRTI) using an FCR tendon autograft, or perform CMC arthrodesis if adjacent bone stock permits.
• Type III (Swan-Neck) Reconstruction:
  • Basal CMC Decompression and Stabilization: The mandatory primary step is restoring the basal articulation and releasing the adducted metacarpal. Perform a complete trapeziectomy with LRTI. If first web space contracture persists after trapeziectomy, execute a formal first web space release (skin Z-plasty, release of the first dorsal interosseous fascia, and adductor pollicis origin slide off the third metacarpal).
  • MCP Joint Management: If MCP hyperextension is flexible and under 30°, perform a palmar capsulodesis, EPB tenodesis, or temporary transarticular K-wire pinning in 10° of flexion. If MCP hyperextension is fixed, exceeds 30°, or exhibits joint degeneration, perform MCP Arthrodesis.
• Type IV (Gamekeeper’s / Valgus Instability) Reconstruction: In early cases with preserved articular cartilage, perform an anatomical UCL repair or reconstruction using a free palmaris longus tendon autograft secured with suture anchors. In patients with advanced chondral erosion or chronic gross valgus instability, MCP Arthrodesis provides the only reliable, permanent solution.
• Type V (Swan-Neck Variant) Reconstruction: Because the CMC joint is anatomically normal, surgery is restricted to the MCP joint. Perform MCP palmar capsulodesis in early flexible cases, or MCP Arthrodesis if articular destruction is established. Leave the basal CMC joint completely undisturbed.
• Type VI (Arthritis Mutilans) Reconstruction: Massive bone resorption requires structural reconstruction. Harvest an intercalary corticocancellous strut bone graft from the anterior iliac crest to bridge the osseous defect, performing multi-joint arthrodesis of the MCP and IP joints over an intramedullary Steinmann pin or retrograde headless compression screw to restore digital length and column stability.
• Management of Concomitant Tendon Ruptures: Attritional rupture of the FPL (Mannerfelt syndrome) requires carpal tunnel decompression, excision of offending scaphoid osteophytes, and tendon reconstruction via flexor digitorum superficialis (FDS) transfer from the ring finger or IP joint arthrodesis. Rupture of the EPL is treated with an extensor indicis proprius (EIP) to EPL tendon transfer.

Indications and Contraindications

Surgical intervention is guided by established clinical criteria:

• Surgical Indications:
  • Intractable joint pain refractory to systemic medical optimization and targeted injections.
  • Progressive functional deformity with loss of lateral key pinch or tip pinch.
  • Gross collateral ligament instability exceeding 30° on stress examination.
  • Radiographic Larsen Grade III, IV, or V articular destruction.
  • Acute tendon rupture of the FPL or EPL requiring reconstructive restoration.
• Contraindications:
  • Absolute: Active superficial or deep infection; medically unstable patient unable to undergo regional or general anesthesia.
  • Relative: Severe uncontrolled systemic inflammatory flare; extreme osteopenia precluding internal fixation stability; unaddressed proximal carpal collapse or wrist instability that destabilizes the distal kinematic chain; patient inability to comply with postoperative splinting and rehabilitation protocols.

9. Outcome

Surgical reconstruction of the rheumatoid thumb delivers consistent improvements in functional stability, lateral pinch strength, and patient-reported outcomes across long-term follow-up.

• Arthrodesis Union Rates: Metacarpophalangeal joint arthrodesis achieves solid osseous union in 95% to 98% of cases across published series. Rigid internal fixation combined with careful subchondral coaptation ensures predictable union despite osteopenic rheumatoid bone.
• Restoration of Pinch Strength: Following successful MCP arthrodesis or basal joint reconstruction, lateral key pinch strength increases from less than 1 to 2 kg preoperatively to a stable, functional range of 3 to 5 kg postoperatively. This provides a rigid post against which the index and long fingers can exert powerful prehension.
• Pain Relief: Over 90% of patients report complete or near-complete pain relief at the reconstructed joint, enabling improved sleep quality and spontaneous hand use in everyday tasks.
• Validated Patient-Reported Outcome Measures (PROMs): Clinical trials and cohort studies consistently document statistically and clinically meaningful improvements on the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire (average improvements exceeding 18 to 24 points), the Michigan Hand Outcomes Questionnaire (MHQ), and the Cochin Hand Function Scale.

10. Complications

Complications associated with rheumatoid thumb reconstruction span intraoperative technical pitfalls, early wound healing disturbances, and late hardware or biomechanical failures.

11. Pearls and Pitfalls

Surgical success in rheumatoid thumb reconstruction requires careful adherence to proven technical principles while avoiding common diagnostic and procedural missteps.

• The Keystone Diagnostic Pearl: Always examine and treat the basal CMC joint before performing an isolated MCP arthrodesis. If an adduction contracture of the first metacarpal is left unaddressed, fusing the MCP joint locks the thumb in the plane of the palm, destroying prehensile span. If the first metacarpal does not easily abduct to 45° intraoperatively, perform a complete trapeziectomy and sequential first web space release.
• Tri-Planar Arthrodesis Positioning: Position the MCP arthrodesis precisely in 10° to 15° of flexion, 5° of abduction, and 5° of pronation. Pronation brings the thumb pulp directly opposite the pulps of the index and middle fingers. Fusing the joint in supination prevents pulp-to-pulp contact and results in awkward fingernail collision during lateral pinch.
• Stepwise First Web Space Release: If first web space narrowing persists after trapeziectomy, proceed through a stepwise release: 1) Skin Z-plasty or four-flap release, 2) Release of the dorsal fascia over the first dorsal interosseous muscle, and 3) Subperiosteal release of the adductor pollicis origin from the third metacarpal shaft.
• Optimizing Fusion Surface Coaptation: In osteopenic rheumatoid bone, avoid simple transverse planar saw cuts that shorten the thumb ray. Utilize ball-and-socket (cup-and-cone) reamers to maximize cancellous surface contact while allowing micro-adjustments in all three spatial planes without bone loss.
• Pitfall – Overlooking Hidden Tendon Ruptures: Always assess active thumb IP flexion and extension prior to anesthesia. A patient presenting with inability to flex the thumb IP joint has an FPL rupture (Mannerfelt syndrome) until proven otherwise. Missing an FPL rupture prior to an MCP arthrodesis will result in persistent postoperative functional failure.
• Pitfall – Overtightening the Extensor Hood: During early Type I extensor reconstruction, avoid excessive advancement or tightening of the EPB tendon. Overtightening creates a rigid extension contracture at the MCP joint and paradoxically worsens extensor forces transmitted to the IP joint.

12. Controversy

Several clinical debates persist regarding optimal operative management for specific stages of rheumatoid thumb disease:

• Trapeziectomy with LRTI vs. CMC Arthrodesis in Type III Swan-Neck Deformity: While CMC arthrodesis provides a rigid basal pillar in non-rheumatoid osteoarthritis, its use in rheumatoid arthritis remains controversial. In rheumatoid patients with diffuse osteopenia and multi-joint involvement, CMC arthrodesis carries a higher nonunion rate (10% to 15%) and transfers excessive stress to neighboring joints. Most contemporary hand surgeons favor complete trapeziectomy with ligament reconstruction and tendon interposition (LRTI) using an FCR autograft or hematoma distraction arthroplasty, which preserves basal compliance, eliminates nonunion risk, and achieves durable pain relief.
• Silicone Interposition Arthroplasty vs. Arthrodesis for the MCP Joint: Flexible silicone hinge implants (Swanson-type spacers) can preserve a 20° to 30° arc of motion at the MCP joint. However, long-term studies reveal high rates of lateral instability under pinch loading, progressive implant fracture, particulate silicone synovitis, and recurrent deformities. Consequently, MCP arthrodesis remains the gold standard, with silicone arthroplasty reserved for rare low-demand patients who have concurrent, irreversible ankylosis or fusion of both the CMC and IP joints on the same ray.
• Timing and Suspension of Biologic DMARDs Around Surgery: Balancing the risk of perioperative infection against the risk of an acute rheumatoid flare remains actively debated. Current consensus guidelines from the American College of Rheumatology (ACR) and the American Association of Hip and Knee Surgeons (AAHKS) recommend withholding biologic agents for one dosing cycle prior to elective surgery and resuming therapy 14 days postoperatively upon complete wound healing. Conversely, conventional synthetic DMARDs (methotrexate, leflunomide) should be safely continued throughout the perioperative period without interruption.

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

• Silva PG, Lombardi I Jr, Breitschwerdt C et al. Functional thumb orthosis for type I and II boutonniere deformity on the dominant hand in patients with rheumatoid arthritis: a randomized controlled study. Clin Rehabil. 2008. doi:10.1177/0269215508088989 [Level I: Randomized Controlled Trial]
• Chacko AT, Rozental TD. The rheumatoid thumb. Hand Clin. 2008. doi:10.1016/j.hcl.2008.03.005 [Level IV: Clinical Review & Algorithmic Cohort]
• Terrono A, Millender L, Nalebuff E. Boutonniere rheumatoid thumb deformity. J Hand Surg Am. 1990. doi:10.1016/0363-5023(90)90032-m [Level IV: Retrospective Cohort Study]
• Nalebuff EA. The rheumatoid thumb. Clin Rheum Dis. 1984. doi:PMID:6532645 [Level IV: Seminal Observational Cohort]
• Nalebuff EA. Diagnosis, classification and management of rheumatoid thumb deformities. Bull Hosp Joint Dis. 1968. doi:PMID:5729736 [Level IV: Seminal Classification Description]

15. Master Class Pro-Tip

Master Class Surgical Pearl: The fundamental error in rheumatoid thumb reconstruction is focusing narrowly on the MCP joint while failing to recognize basal carpometacarpal subluxation and adduction contracture. Fusing an MCP joint in the presence of an adducted first metacarpal leaves the patient with a nonfunctional thumb permanently trapped in the plane of the palm, destroying the grasp cylinder. Always assess the basal CMC joint on a true Robert’s projection. In Nalebuff Type III swan-neck collapse, the basal joint must be decompressed and mobilized first through trapeziectomy with ligament reconstruction and tendon interposition (LRTI) or adductor release before stabilizing the MCP joint. When performing an MCP arthrodesis, position the joint strictly in 10° to 15° of flexion, 5° of abduction, and 5° of pronation. This exact tri-planar alignment ensures direct pulp-to-pulp contact with the index and long fingers while preserving the functional thumb-index grasp cylinder.

Master Class Surgical Pearl: Principles of Rheumatoid Thumb Reconstruction