[Short-term results of the IPP 2 proximal interphalangeal joint prosthesis]

The most commonly used type of proximal interphalangeal joint prosthesis is a silicone spacer. A variety of other types of prosthesis have been used over the years. The originalty of our new prosthesis lies in its mode of bone anchorage; namely osseointegration. DESCRIPTION OF PROSTHESIS AND OPERATIVE TECHNIQUE: Two titanium covered screws are inserted in the medullary canals of the proximal and middle phalanges. A connecting hinge allows movement from 0 degrees to 100 degrees. Implantation can be performed without the need for specialised instrumentation. A preoperative template allows the size of screw to be determined in advance.

Twenty-eight prostheses were implanted of which 24 were reviewed at a minimum follow up interval of 3.9 years. The diagnosis was primary osteoarthritis in 13 cases and 6 cases were secondary to trauma. Six of the 21 surviving prostheses had a mean follow up period of 6 years (5-14) and 15 a mean of 3 years (2-4). The mean range of movement was -12/55 degrees preoperatively and -9/77 degrees postoperatively. Three patients underwent revision surgery. There was condensation of bone around the proximal screw discernable after 6 months. There were no visible changes in the middle phalanx. The prosthesis did not subside into the proximal phalanx.

Osseointegration has only recently been taken up in orthopaedics as a means of bone anchorage. In our experience the IPP2 prosthesis had excellent integration in all cases and to date there has been only one hinge breakage.