The aim was to compare the medium term results of metacarpophalangeal joint (MCPJ) arthroplasty using three different types of silicone hinged implants.

All rheumatoid arthritis patients undergoing four finger MCPJ arthroplasty at Burwood Hospital have had standardised pre and post operative assessments for up to four years consisting of: measurement of MCPJ active arc of motion (AOM); finger ulnar drift (UD) and the Baltimore upper extremity function test (UEFT). All surgery was undertaken or directly supervised by one surgeon using a standardised technique followed by a dynamic and static splintage programme supervised by the same hand therapists.

Implants – Swanson; 25 hands, 100 joints, 1989 to 1995 – Avanta; 27 hands, 108 joints, 1995 to 2000 – Neuflex; 11 hands, 44 joints, 1999 to 2003

Swanson – at two years the AOM changed from 46 – 80° to 15 – 51°; UD reduced from 33 to 4°and 66% had improved from partial and poor to functional UE categories.

Avanta – the AOM changed from 51 – 79 to 15– 60; UD from 31 to 7° and 67% had improved to functional.

Neuflex – the AOM changed from 42 – 68 to 17 – 63°; UD from 32 to 11 and 45% had improved to functional classification.

From two to four years the UEFT for the Swanson and Avanta had significantly deteriorated.

The medium term outcomes for the three implants were very similar. Neuflex use was discontinued in 2003 because of early recurrence of ulnar drift. The significant deterioration of hand function from two to four years is likely to be the effect of progressive rheumatoid disease as the AOM and UD remained unchanged.