Small Joint Arthroplasty of the Hand

Indications for Small Joint Arthroplasty

Contraindications

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MCP Joint Anatomy

The metacarpophalangeal joint is a condyloid (ellipsoid) joint permitting flexion, extension, abduction, adduction, and limited rotation. Key anatomical structures include the collateral ligaments (taut in flexion, lax in extension - critical for rehabilitation), accessory collateral ligaments, volar plate, and the dorsal extensor hood mechanism. In rheumatoid arthritis, synovitis leads to progressive destruction with stretching of the radial sagittal band, ulnar subluxation of the extensor tendons, and the characteristic ulnar drift deformity. The intrinsic muscles (interossei and lumbricals) contribute to deformity through their altered line of pull.

PIP Joint Anatomy

The proximal interphalangeal joint is a bicondylar hinge joint with primary motion in the sagittal plane (flexion-extension). Stability is provided by proper and accessory collateral ligaments, the volar plate, and the central slip of the extensor mechanism. The PIP joint withstands forces up to 3 times body weight during pinch grip. In osteoarthritis, marginal osteophytes (Bouchard nodes) form dorsally and laterally. In rheumatoid arthritis, progressive synovitis leads to boutonniere deformity (central slip attenuation, PIP flexion, DIP hyperextension) or swan neck deformity (PIP hyperextension, DIP flexion).

CMC Joint Anatomy

The thumb carpometacarpal joint is a saddle (sellar) joint between the trapezium and first metacarpal base, permitting opposition, flexion, extension, abduction, and adduction. The joint is stabilized by the anterior oblique (beak) ligament (most important for stability), dorsoradial ligament, posterior oblique ligament, and intermetacarpal ligament. Primary osteoarthritis preferentially affects this joint in postmenopausal women due to ligamentous laxity and repetitive loading. Pantrapezial arthritis extends to the scaphotrapezial and trapeziotrapezoid joints.

Before committing to arthroplasty, confirm the correct diagnosis and joint. Several conditions mimic primary degenerative or rheumatoid joint destruction and change the operation entirely.

Implant-Related Complications

Deformity Recurrence

Other Complications

MCP Arthroplasty Outcomes

PIP Arthroplasty Outcomes

Thumb CMC Arthroplasty Outcomes

Trapeziectomy (with or without LRTI):

• Good pain relief in roughly 78% of patients in long-term RCT follow-up (Gangopadhyay), and higher in observational series
• Grip and pinch strength recover, although pinch may decline slowly over years irrespective of technique
• Subsidence (proximal metacarpal migration) is near-universal but correlates poorly with symptoms
• Return to function: 3-6 months (longer than digit arthroplasty)
• Total joint (dual-mobility) prostheses show faster early recovery in some series but lack the long-track-record durability data of trapeziectomy

The long-term series paint a pessimistic radiographic picture (deteriorating motion, recurrent drift, majority implant fracture), which raises a fair examiner question: is silicone MCP arthroplasty worth doing and worth funding? The health-economic evidence answers this more favourably than the survivorship data alone would suggest. The critical point is that the value of the operation depends heavily on which outcome instrument is used - a hand-specific, patient-rated measure captures the real benefit far better than a whole-body arthritis-impact scale.

• Outcomes are durable when measured well. In the Squitieri prospective cohort, the functional gains of surgery were maintained across the full 5-year follow-up rather than eroding, when measured with the hand-specific Michigan Hand Outcomes Questionnaire.
• Cost per unit of benefit is modest. Improved hand-specific outcomes were achieved at a relatively low incremental cost, so silicone MCP arthroplasty looks cost-effective on a hand-specific measure even after accounting for the possibility of complications and revision.
• The instrument matters enormously. The same improvement looks very expensive when forced onto a generic whole-body arthritis-impact scale, because rebuilding a few finger joints barely moves a systemic disease score. This is a general trap in rheumatoid hand surgery: judging a focal hand operation by a whole-patient outcome measure understates its true value.
• Revision does not sink the economics. The favourable cost-effectiveness held even when the observed and previously published revision rates (around 5 to 6 percent) were built into the model.

This reconciles the apparent contradiction between the gloomy long-term radiographic series and continued use of the procedure: for the severely deformed, painful rheumatoid hand, silicone MCP arthroplasty delivers durable, patient-valued functional improvement at acceptable cost - provided it is judged by what the hand can do, not by a systemic disease score.

Global Epidemiology

• Thumb CMC (trapeziometacarpal) osteoarthritis is the most common small-joint indication worldwide, with a strong female and post-menopausal predominance; radiographic basal-joint OA is found in roughly a third of post-menopausal women.
• Rheumatoid arthritis affects approximately 0.5-1% of adults globally. The classic severely deformed rheumatoid MCP hand requiring arthroplasty is becoming less common as early biologic and conventional DMARD therapy controls disease before joint destruction.
• Erosive/inflammatory hand OA and post-traumatic arthritis make up most remaining PIP and MCP arthroplasty caseload.

Side-by-Side Guidance

Registry and Evidence Notes

• Unlike hip and knee arthroplasty, small joint arthroplasty is poorly captured by national joint registries; most outcome data come from single-centre series and a small number of RCTs (Gangopadhyay; Chung). This limits implant-level comparative survivorship data.
• The consistent registry-independent message: trapeziectomy-based procedures are durable and additional ligament reconstruction adds morbidity without benefit; silicone MCP implants fracture frequently but the encapsulation arthroplasty continues to function.

High- vs Limited-Resource Practice Variation

• In well-resourced settings, certified hand therapists and dynamic splinting protocols are integral to MCP arthroplasty outcomes, and pyrocarbon or total joint implants are available at higher cost for selected motion-preserving indications.
• In limited-resource settings, arthrodesis and simple trapeziectomy are favoured because they are cheap, reliable, and require less specialised post-operative therapy and follow-up. The reduced dependence on hand-therapy infrastructure is a legitimate driver of procedure choice, not a compromise of standards.

Two of the classic failings of the silicone spacer - implant fracture and particulate silicone synovitis - were both attributed, in part, to abrasion of the flexible stem against the sharp cut edge of bone at the mouth of the medullary canal. To counter this, Swanson introduced grommets: small titanium eyelets seated in the canal entrance at the bone-implant junction, interposing a smooth, rigid collar between the silicone and the bone so the stem no longer chafes against a bony edge. The theoretical case is attractive - protect the weakest part of the hinge and reduce the shedding of the silicone particles that provoke synovitis and osteolysis.

The clinical evidence has not supported it. In Trail's large 17-year survivorship series the use of grommets did NOT protect the implant from fracture, and grommets add cost, technical steps, and their own potential for malposition or loosening. The modifiable factors that genuinely prolonged survival in that series were soft-tissue balancing, crossed intrinsic transfer, and wrist realignment - not the hardware. Grommets may still be considered where the priority is limiting particulate wear and synovitis rather than fracture, but they should never be relied on to prevent implant breakage, and many surgeons now omit them.

1. Swanson AB. Flexible implant resection arthroplasty. Hand. 1972;4(2):119-134.

2. Goldfarb CA, Stern PJ. Metacarpophalangeal joint arthroplasty in rheumatoid arthritis. A long-term assessment. J Bone Joint Surg Am. 2003;85(10):1869-1878.

3. Trail IA, Martin JA, Nuttall D, Stanley JK. Seventeen-year survivorship analysis of silastic metacarpophalangeal joint replacement. J Bone Joint Surg Br. 2004;86(7):1002-1006.

4. Vermeulen GM, Slijper H, Feitz R, et al. Surgical management of primary thumb carpometacarpal osteoarthritis: a systematic review. J Hand Surg Am. 2011;36(1):157-169.

5. Gangopadhyay S, McKenna H, Burke FD, Davis TRC. Five- to 18-year follow-up for treatment of trapeziometacarpal osteoarthritis. J Hand Surg Am. 2012;37(3):411-417.

6. Sweets TM, Stern PJ. Pyrolytic carbon resurfacing arthroplasty for osteoarthritis of the proximal interphalangeal joint of the finger. J Bone Joint Surg Am. 2011;93(15):1417-1425.

7. Chung KC, Burns PB, Wilgis EFS, et al. A multicenter clinical trial in rheumatoid arthritis comparing silicone metacarpophalangeal joint arthroplasty with medical treatment. J Hand Surg Am. 2009;34(5):815-823.

8. Eaton RG, Glickel SZ. Trapeziometacarpal osteoarthritis. Staging as a rationale for treatment. Hand Clin. 1987;3(4):455-471.

9. Squitieri L, Chung KC, Hutton DW, et al. A 5-year cost-effectiveness analysis of silicone metacarpophalangeal arthroplasty in patients with rheumatoid arthritis. Plast Reconstr Surg. 2015;136(2):305-314.

10. Burton RI, Pellegrini VD Jr. Surgical management of basal joint arthritis of the thumb. Part II. Ligament reconstruction with tendon interposition arthroplasty. J Hand Surg Am. 1986;11(3):324-332.