Biomechanical Evaluation of Recurrent Dissociation of Modular Humeral Prostheses.

The purpose of the study was to evaluate the force and torque required to dissociate a humeral head from the unimplanted modular total shoulder replacement system from different manufacturers and to determine if load and torque to dissociation are reduced in the presence of bodily fluids. Impingement, taper contamination, lack of compressive forces, and interference of taper fixation by the proximal humerus have all been reported as possible causes for dissociation. Experimental values determined in this research were compared with literature estimates of dissociation force of the humeral head under various conditions to gain more understanding of the causes of recurrent dissociations of the humeral head.

Ring-Shaped Lateral Meniscus Without a Bony Anterior Root Attachment.

The discoid lateral meniscus has been well described. The ring-shaped lateral meniscus was not originally included in the classification systems but has been reported in the literature several times. This article describes a unique variation of the ring lateral meniscus in which the anterior root attachment was to the anterior cruciate ligament and rendered unstable with preparation of the anterior cruciate ligament reconstruction tunnels.