Passive kinematics and laxity of prosthetic knees and intact knees as measured by a novel computer-assisted system.

A system was developed for recording and analyzing passive kinematics and laxity of intact and operated knees using contemporary infrared surgical navigation hardware with custom-written data analysis software. Initial results are presented, suggesting that intra- and interobserver laxity assessment and kinematic behavior with the knee intact vs arthrotomy performed are repeatable. Normal and diseased knees have distinct kinematic and laxity behaviors, but, because of the laxity of the quadriceps in this study, additional data are needed before generalizations can be made.

Kinematics, kinetics, and finite element analysis of commonplace maneuvers at risk for total hip dislocation.

Dislocation remains a disturbingly frequent complication of total hip arthroplasty (THA). Over the past several years, increasingly rigorous biomechanical approaches have been developed for studying dislocation, both experimentally and computationally. Realism of the input motion challenge data has lagged behind most other aspects of this body of work, and anterior dislocation maneuvers remain unstudied.

Effects of acetabular component orientation on dislocation propensity for small-head-size total hip arthroplasty.

Objective: Examine the role of surgical orientation of the acetabular cup on posterior dislocation propensity for small-head-size total hip arthroplasty.

Design: A finite element model of a widely used total hip arthroplasty system was examined for peak resisting moment and range-of-motion prior to impingement, as well as prior to onset of posterior dislocation. Acetabular component surgical orientation was varied.