Biomechanical and biological considerations relating to the clinical use of the Point Contact-Fixator - Evaluation of the device handling test in thetreatment of diaphyseal fractures of the radius and/or ulna

The Point Contact-Fixator (PC-Fix) was designed as part of the developmenta l evolution of more biological devices for internal fixations. It is a devi ce characterized by minimal contact to the underlying periosteum and bone, hereby minimizing potential damage to perfusion. A multicentre handling tes t was conducted in 1993 and 1994 in six hospitals to assess its performance . A total of 83 fractured forearm bones (34 radii and 49 ulnae) in 52 patie nts were stabilized with a PC-Fix. The mean age of the patients was 37 year s. There were 24 AO type A, 24 type B and 5 type C fractures. Nine fracture s were open. Mean follow-up was 15.6 months; follow-up was 100%. All 21 sur geons involved considered the use of the PC-Fix self-explanatory and relati vely easy. Handling difficulties were mainly related to insertion of the mo nocortical screws. In particular, the precision required for insertion, the inability to incline the screw and the inability to pull the plate to the bone using the screw were considered hard to deal with. Stripping of the he xagonal slot was a problem at removal of the implant, possibly related to o vertightening of the screws at insertion. In 76 of 83 bones (49 of 53 forea rms), the fractures united without additional surgery. The healing pattern typically showed early callus formation bridging the fracture, followed by progressive mineralization of the central radiolucent line. Complications i ncluded one infection, one late displacement and four delayed unions, all r equiring revision surgery. In 8 forearms, plate removal was performed after a mean of 10.3 months. Two refractures occurred after removal of the impla nt 6 and 7 months postoperatively. In conclusion, the practical handling of the new implant was straightforward and easily learnt. The treatment failu res observed were related to technical and strategic errors. We consider th at, when using devices with a locking compression principle, a minimum numb er of three screws should be placed on each side of the fracture, that inte rfragmentary compression of simple fractures is desirable in order to incre ase stability and that, contrary to in vivo animal studies, early plate rem oval is not indicated. The trend in fracture fixation is to improve the bio mechanical and biological properties of operating technique and the devices used. The PC-Fix has proven a useful step in the right direction in this e volutionary process.