Osseointegrated proximal interphalangeal joint prostheses with a replacable flexible joint spacer - Long term results

Osseointegrated proximal interphalangeal joint prostheses with a replacable joint spacer,were used in 25 joints in 19 patients (five men and 14 women) aged 45 (16-67) years. Indications for surgery were post-traumatic arthros is (nine joints in eight patients), primary osteoarthrosis (10 joints in ei ght patients), and rheumatoid arthritis (six joints in three patients). A s ilicone joint spacer was attached to titanium fixtures by short titanium st ems that extended from the spacer and fitted into a central canal in the sc rews. The arthroplasty was done in one stage, which included resection of t he joint followed by grafting of marrow and cancellous bone from the iliac crest into adjacent medullary cavities before insertion of the titanium fix ture. Follow up at 8.5 (5-11) years showed that 47 out of 50 fixtures (94%) had successfully osseointegrated while 17 of 25 joint spacers (68%) had fr actured. However, because of the design of the prostheses fractured joint s pacers could easily be replaced and a new spacer could be connected to alre ady osseointegrated screws. The joint spacer was replaced in 11 fingers onc e or several times. Range of movement (ROM) in the whole series (four fusio ns excluded) was 41 (0-85)degrees with an extension defect of 15 (0-55)degr ees. In eight joints with permanently intact joint spacers the ROM was 39 ( 0-60)degrees with extension defects of 16 (0-40)degrees. In six joints in w hich the spacer was replaced once the ROM was 43 (0-85)degrees with an exte nsion defect of 16 (0-55)degrees. Our data confirm good long-term osseointe gration of titanium fixtures and that a joint spacer, if needed, can be rep laced by a new spacer that can be attached to already osseointegrated screw s without jeopardising the ROM.