Rolling and translational gliding in opposite directions combine to a result of no net linear displacement. However the angular component of the rolling remains to produce some net angular displacement. The end result (but not the process) are equivalent to tangential glide as a component of true angular motion.
STRUCTURE-BASED PREDICTION OF JOINT MOTION
P.V. Loubert 1 , T.J. Masterson 2 , A. Saltarelli 2
1 School of Rehabilitation and Medical Sciences
2 School of Health Sciences
Central Michigan University, Mt. Pleasant, MI 48859
Our hypothesis states that for any given synovial joint, the range of motion (ROM) can be predicted by subtracting the concave arc from the convex arc of the respective articular surfaces in a joint (see Figure 1) .
Our results indicate that there is a moderate correlation, r = 0.77, between the measured and predicted ROM, as well as between the published and predicted ROM, r = 0.77.
Several kinematic relationships were observed between articular surfaces during movement that suggest additional considerations that must be taken into account in order to achieve a higher correlation between joint structure and function. These included:
1) Violations of the assumption that the articular surfaces would be in contact during the entire movement, and
2) The transection of the joint must be in the true plane of movement.
CHANGES IN GEOMETRIC AXES OF ROTATION A B A + B = ROM