Role of collateral ligaments in the GSB-linked total elbow prosthesis

The GSB III elbow prosthesis is a loose-hinged type of elbow implant. The i ntroduction of such hinged elbow arthroplasty expanded the indications for elbow replacement to patients with more deficient bone and ligaments. The p urpose of this study was to compare the kinematics and stability of the GSB III elbow prosthesis with that of the normal elbow and to investigate the role of the collateral ligaments in the kinematics and the stability of the GSB III total elbow prosthesis in an in vitro model. The results could sho w a semiconstrained kinematic pattern of the GSB III implant. The mean laxi ty for varus/valgus stress of the implant without collateral ligament suppo rt was significantly greater for all flexion angles when compared with inta ct elbows (mean, 12.7 degrees versus 5.4 degrees) and with elbows treated w ith a standard implantation technique (mean, 9.5 degrees). The release of t he collateral ligaments increased the already observed varus shift after st andard implantation of a GSB III elbow prosthesis. The laxity measured with out collateral ligaments during loaded movement reached the maximum varus/v algus laxity of the GSB III prosthesis of 12 degrees degrees. The study con firms the role of the collateral ligaments in stabilizing the GSB III elbow prosthesis. Missing collateral ligaments may overload the implant-cement-b one interface and may be one Factor contributing to early aseptic loosening of this device.