Silicone (Swanson) MCP Joint Arthroplasty — Procedure Outcomes & Post-operative Rehabilitation

Topic scope: post-operative rehabilitation after silicone (Swanson) replacement of the metacarpophalangeal (MCP) joints — flexible silicone-elastomer spacer arthroplasty of the knuckle joints, most often for the rheumatoid hand with ulnar drift and volar subluxation, and less commonly for MCP osteoarthritis. This is a resection-replacement with soft-tissue rebalancing, not a simple decompression: the deforming forces that destroyed the joint (ulnar drift, extensor subluxation, intrinsic tightness) are still present, so the rehabilitation is an active, splint-driven re-shaping programme, not a rest-and-protect pathway.

Defining principle of the rehab here: a silicone MCP implant is a flexible spacer around which a new fibrous capsule ("encapsulation") forms over the first weeks — and that capsule remodels in whatever position the hand is held. The classic post-operative regime therefore uses a dynamic extension outrigger splint that holds the MCPs in extension with slight radial deviation (opposing the ulnar drift) while permitting early controlled active flexion against elastic loops. Move early, but only in the corrected position: this is what reverses the drift and builds a functional flexion arc. The single biggest branch point is the diagnosis — the rheumatoid hand drifts and recurs far more readily than the osteoarthritic hand and warrants more diligent, more prolonged radial-deviation splinting.

A. PROCEDURE OUTCOMES (rheumatoid and osteoarthritis)

Silicone MCP arthroplasty is a deformity-correcting, pain-relieving operation rather than a motion- or strength-restoring one. Its great strength is reliable correction of alignment and relief of pain; its accepted limitations are a modest final arc, gradual implant fracture over years, and—in rheumatoid hands—a tendency to recurrent drift.

• In rheumatoid arthritis it produces durable improvement in deformity, appearance and patient-reported function. The multicentre prospective SARA (Silicone Arthroplasty in Rheumatoid Arthritis) cohort compared 70 surgical with 93 non-surgical RA patients with severe MCP deformity: the surgical group showed significant, sustained gains in the Michigan Hand Outcomes Questionnaire and in ulnar deviation, extensor lag and arc of motion, maintained at 1 year, at long-term (3-year) follow-up, and out to 7 years, whereas the non-surgical cohort did not improve [Chung 2009; Chung 2012; Chung 2017]. Moderate–strong (prospective comparative cohort; not randomised).
• Correction of ulnar drift and extensor lag is the headline result; arc and grip gains are modest. Series consistently report large reductions in ulnar deviation and extensor lag with a re-centred, more functional arc (commonly a final arc on the order of ~40–50° centred nearer extension), with grip strength only modestly changed. The operation buys alignment, pain relief and hand appearance/function, not power [Goldfarb & Dovan 2006; Rizzo 2011; Kirschenbaum 1993]. Moderate.
• For MCP osteoarthritis, long-term results are favourable and durable. A long-term series of silicone MCP arthroplasty for OA reported lasting pain relief and satisfactory function, with better-preserved bone stock and less recurrent deforming force than the rheumatoid hand [Morrell & Weiss 2018]. Moderate.
• Implant fracture accrues with time but is often clinically silent. Long-term radiographic follow-up shows implant fracture rates rising over the years, yet many fractured implants remain asymptomatic and revision is driven by symptoms/instability rather than radiographic fracture alone [Koenuma 2024; Kirschenbaum 1993]. Moderate.
• Revision is uncommon but defined, most often for recurrent deformity, implant fracture/instability or infection; revision MCP arthroplasty is feasible but technically demanding with poorer results than primary surgery [Wagner 2019; Carlson Strother 2023]. Moderate.

B. REHABILITATION / THERAPY EVIDENCE

The central rehab questions are (1) which splint regime, and (2) does adding continuous passive motion or particular splint variants change the outcome. The evidence base is dominated by a strong heritage regime (Swanson-style dynamic extension splinting) supported mostly by expert consensus and low-level studies, with the few controlled comparisons failing to show benefit from add-ons. The rehabilitation is nonetheless indispensable — it is integral to the operation, not an optional adjunct.

• The standard regime is a dynamic extension outrigger splint with early controlled motion. Fitted within the first few days, it holds the MCPs in extension and slight radial deviation at rest and permits active flexion against finger slings, worn essentially continuously for ~6 weeks then weaned to night/rest splinting. The shared aim across published regimes is to encourage MCP flexion and extension without recurrence of flexion contracture or ulnar deviation while the capsule encapsulates the implant in a corrected position [Goldfarb & Dovan 2006; Massy-Westropp Cochrane 2008]. Consensus / heritage — widely practised, low-level evidence.
• Adding continuous passive motion (CPM) to dynamic splinting does not help. The Cochrane review identified a single small controlled trial (22 participants) comparing dynamic splinting ± CPM and concluded CPM is not effective at increasing motion or strength after MCP arthroplasty (controls actually gained more motion); it rated the evidence "silver level" and called for well-designed RCTs given wide practice variation [Massy-Westropp Cochrane 2008]. Moderate (Cochrane SR of low-certainty primary evidence).
• A static-splint alternative achieves comparable correction in small studies. A prospective series using alternating static flexion/extension splints (rather than a dynamic outrigger) reported improved total active arc (21.6°→47.2°) and corrected ulnar deviation (30.4°→9.7°), suggesting the position held and active motion matter more than the specific splint mechanism [Burr/Massy-Westropp J Hand Ther 2002]. Weak (small prospective cohort).
• The specific dynamic-splint protocol has not been shown superior to simpler regimes in controlled comparison. A randomised study found no clear added value of dynamic splinting over a simpler post-operative regime for MCP replacement, reinforcing that the dynamic outrigger is a sound, traditional default rather than a proven optimum [Delaney 2003]. Weak–moderate (small RCT).

Recovery trajectory (expected, evidence-anchored)

(Phase windows mirror the patient protocol; they are typical, heritage-based guides — not trial-derived deadlines.)

C. KEY CONTROVERSIES / EVIDENCE QUALITY

1. Heritage regime, modest evidence. The Swanson-style dynamic extension outrigger with early controlled motion is deeply established and near-universally taught, but its supporting evidence is largely expert consensus and small/low-level studies. The defensible position is to follow the heritage regime faithfully while acknowledging its evidence tier [Goldfarb & Dovan 2006; Massy-Westropp Cochrane 2008]. Consensus.
2. Which splint? Dynamic outrigger vs alternating static splints vs simpler regimes give broadly similar correction in small studies; CPM adds nothing. What matters is holding the MCPs in extension + radial deviation while moving early — the mechanism of the splint is secondary [Massy-Westropp Cochrane 2008; Burr 2002; Delaney 2003]. Weak–moderate.
3. Rheumatoid vs osteoarthritis. The rheumatoid hand has ongoing deforming forces (tendon subluxation, intrinsic tightness, soft-tissue laxity) and recurs, demanding more prolonged radial-deviation/night splinting and joint protection; the osteoarthritic hand has better bone and soft tissue and a more durable correction [Morrell & Weiss 2018; Rizzo 2011]. Moderate.
4. Realistic goals. The operation reliably delivers pain relief, corrected alignment and a functional arc, not a normal or powerful hand. Mis-set expectations (large grip gains) are a common source of dissatisfaction [Chung patient-expectations 2015; SARA cohort]. Moderate.
5. Implant fracture ≠ failure. Radiographic implant fracture accrues over years but is frequently asymptomatic; revision is symptom-driven. Counsel accordingly rather than revising on imaging alone [Koenuma 2024; Wagner 2019]. Moderate.

D. EVIDENCE STRENGTH FLAGS (summary)

• MODERATE–STRONG: silicone MCP arthroplasty improves deformity, alignment (ulnar deviation, extensor lag), MHQ and arc versus non-surgical care in severe rheumatoid MCP disease, durable to 7 years (SARA prospective cohort — comparative, not randomised).
• MODERATE: correction-over-power outcome profile; favourable long-term OA results; time-related implant fracture (often asymptomatic); defined but uncommon revision rate; greater recurrence in rheumatoid than osteoarthritic hands.
• WEAK / CONSENSUS / HERITAGE: the specific dynamic-extension-outrigger + early-controlled- flexion + radial-deviation rehabilitation programme (strong heritage, low-level evidence; CPM shown unhelpful; dynamic vs static vs simpler regimes not clearly differentiated); exact phase timings (typical, not trial-derived).

CITATIONS

RAG corpus (180,000+ Orthopaedic articles)

• Kirschenbaum D, Schneider LH, Adams DC, et al. Arthroplasty of the metacarpophalangeal joints with use of silicone-rubber implants in patients who have rheumatoid arthritis. Long-term results. J Bone Joint Surg Am. 1993;75(1):3-12. DOI: 10.2106/00004623-199301000-00002
• Goldfarb CA, Dovan TT. Rheumatoid arthritis: silicone metacarpophalangeal joint arthroplasty indications, technique, and outcomes. Hand Clin. 2006;22(2):177-188. DOI: 10.1016/j.hcl.2006.02.001
• Rizzo M. Metacarpophalangeal joint arthritis. J Hand Surg Am. 2011;36(2):345-353. DOI: 10.1016/j.jhsa.2010.11.035
• Morrell NT, Weiss AC. Silicone metacarpophalangeal arthroplasty for osteoarthritis: long-term results. J Hand Surg Am. 2018;43(3):229-233. DOI: 10.1016/j.jhsa.2017.10.010
• Koenuma N, Ikari K, Oh K, et al. Long-term implant fracture rates following silicone metacarpophalangeal joint arthroplasty in rheumatoid arthritis. J Hand Surg Am. 2024. DOI: 10.1016/j.jhsa.2024.01.009
• Wagner ER, Houdek MT, Packard B, et al. Revision metacarpophalangeal arthroplasty: a longitudinal study of 128 cases. J Am Acad Orthop Surg. 2019. DOI: 10.5435/JAAOS-D-17-00042
• Carlson Strother CR, Moran SL, Rizzo M. Small joint arthroplasty of the hand: an update on indications, outcomes, and complications. J Am Acad Orthop Surg. 2023;31(15):e739-e749. DOI: 10.5435/JAAOS-D-23-00034
• Blazar PE, Gancarczyk SM, Simmons BP. Rheumatoid hand and wrist surgery: soft tissue principles and management of digital pathology. J Am Acad Orthop Surg. 2019;27(21):e924-e933. DOI: 10.5435/JAAOS-D-17-00608
• Naniwa S, Nishida K, Nasu Y, et al. A comparative study of short-term outcomes between INTEGRA and AVANTA silicone implants for metacarpophalangeal joints in patients with rheumatoid arthritis. J Hand Surg Am. 2026. DOI: 10.1016/j.jhsa.2026.04.003

MCP arthroplasty outcomes & rehabilitation literature (URLs)

• 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. DOI: 10.1016/j.jhsa.2009.01.018 — https://pmc.ncbi.nlm.nih.gov/articles/PMC4381953/
• Chung KC, Burns PB, Kim HM, et al. Long-term followup for rheumatoid arthritis patients in a multicenter outcomes study of silicone metacarpophalangeal joint arthroplasty. Arthritis Care Res (Hoboken). 2012;64(9):1292-1300. DOI: 10.1002/acr.21705 — https://pubmed.ncbi.nlm.nih.gov/22511483/
• Burns PB, Zhong L, Chung KC. Seven-year outcomes of the Silicone Arthroplasty in Rheumatoid Arthritis (SARA) prospective cohort study. Arthritis Care Res (Hoboken). 2017. DOI: 10.1002/acr.23105 — https://pmc.ncbi.nlm.nih.gov/articles/PMC5376377/
• Chung KC, Burns PB, et al. Patient expectations and long-term outcomes in rheumatoid arthritis patients: results from the SARA study. Clin Rheumatol. 2015;34(4):641-651. DOI: 10.1007/s10067-014-2775-z — https://pubmed.ncbi.nlm.nih.gov/25267562/
• Massy-Westropp N, Johnston RV, Hill C. Post-operative therapy for metacarpophalangeal arthroplasty. Cochrane Database Syst Rev. 2008;(1):CD003522. DOI: 10.1002/14651858.CD003522.pub2 — https://pmc.ncbi.nlm.nih.gov/articles/PMC8715905/
• Burr N, Pratt AL, Stott D. An alternative splinting and rehabilitation protocol for metacarpophalangeal joint arthroplasty in patients with rheumatoid arthritis. J Hand Ther. 2002;15(1):41-47. DOI: 10.1053/hanthe.2002.v15.01541 — https://pubmed.ncbi.nlm.nih.gov/11866351/
• Delaney R, Trail IA, Nuttall D. Value of dynamic splinting after replacement of the metacarpophalangeal joint in patients with rheumatoid arthritis. Scand J Plast Reconstr Surg Hand Surg. 2003;37(4):232-233. DOI: 10.1080/02844310310005658 — https://pubmed.ncbi.nlm.nih.gov/12755512/