Silicone-rubber interposition arthroplasty of the carpometacarpal joint of the thumb.

Since 1969, a slightly modified silicone-rubber neurosurgical burr-hole cover has been used for a type of interposition arthroplasty of the carpometacarpal joint of the thumb. The short stem of the device fits into a hole burred into the distal surface of the trapezium. The flat surface of the device covers the distal surface of the trapezium. Forty-nine operations were done on 42 patients, 35 women and seven men. The age range of the patients was 34 years to 72 years, with an average of 55 years. The average follow-up time was 31 months. Forty results were rated as excellent. There were two failures due to breakage of the device, and in both cases the breakage was due to a technical error.