Bone remodeling phenomena in flexible implant arthroplasty in the metacarpophalangeal joints. Long-term study

The durability of any implant procedure is related to the host bone tolerance. This can be evaluated in part by measuring the cortical bone thickness around the device. The purpose of this study is to evaluate the long-term bone response to silicone implants at the metacarpophalangeal joint level in a series of 133 digits with a minimum of five years of follow-up evaluation. A method of bone morphometry that can measure cortical bone thickness on radiograms was used. Bone remodeling resulted in the formation of a newly formed cortical bony shell around the implant stems and maintenance of the shape of the cut end of the bone with thickening of the cortical bone at the metacarpal and phalangeal metaphysis. Thickening of the phalangeal midshaft was also present. A postoperative decrease of the metacarpal midshaft cortical bone thickness was related to the surgical reaming and remained permanently. Compared with the initial postoperative length, there was no shortening of the proximal phalanx and an average shortening of 9.1% in the metacarpal. The shape of the cortical bone in implant resection arthroplasty can be maintained and the bone thickness increased.