Correlation between range of motion and implant fracture: a 5 year follow-up of 72 joints in 18 patients in a randomized study comparing Swanson and Avanta/Sutter MCP silicone prosthesis.

Eighteen out of 18 rheumatoid patients (at one centre of a two-centre 30 patient study previously reported) with a mean age of 56 years, and 72/72 operated joints were randomized to Avanta/Sutter or Swanson MCP prostheses and followed for 5 years. Both ulnar deviation and extension lag were improved already at 6 weeks and remained improved at 5 years. The Avanta prosthesis had a better range of motion (ROM) than the Swanson. Six of nine patients with Avanta/Sutter implants had at least one implant fracture compared to 1/9 patients with the Swanson implant (P = 0.05) but fracture did not change the outcome subjectively. The ROM at 3 months correlated with the occurrence of an implant fracture at 5 years and a greater early ROM may be related to implant fracture. At 5 years patients remained satisfied and the deformities remained corrected.