Tibial base design and patient morphology affecting tibial coverage and rotational alignment after total knee arthroplasty.

Purpose: To understand interactions between total knee arthroplasty tibial base design attributes, variations in tibial morphology, and the resulting tibial coverage and rotational alignment.

Methods: Tibial anthropometric measurements, including aspect ratio (medial-lateral width/anterior-posterior length) and tibial asymmetry, were taken for 14,791 total knee arthroplasty patients and compared with the ability of four different commercial tibial base designs to cover the resected plateau. The anthropometric measurements were also compared with the resulting tibial base rotation, which occurred when rotating the base to maximize coverage.

Influence of loading and activity on the primary stability of cementless tibial trays.

Several potential advantages exist for cementless tibial fixation including preservation of bone stock and increased longevity of fixation. However, clinical results have been variable, with reports of extensive radiolucent lines, rapid early migration, and aseptic loosening. The primary stability of an implant depends on the micromotion of the bone-implant interface, which depends on the kinematics and kinetics of the replaced joint.

Cross-linked glenoid prosthesis: a wear comparison to conventional glenoid prosthesis with wear particulate analysis.

Wear debris has been observed in shoulder arthroplasties that use an ultrahigh-molecular weight polyethylene (UHMWPE) glenoid component, and the biologic response to this debris contributes to aseptic loosening of the implant. The objective of this study was to assess the wear and particle morphology of a cross-linked UHMWPE prosthetic glenoid. To our knowledge, this is the first time a simulator with kinematic considerations for assessing wear has been used in a shoulder model.

Prosthetic positioning in total shoulder arthroplasty.

Accurate positioning of the prosthetic humeral head is necessary to reproduce normal glenohumeral kinematics and to avoid damage to the rotator cuff and impingement on the glenoid component or coracoacromial arch. Proper positioning of the head requires accurate placement of the stem and prosthetic designs that allow the head position to adapt to the variations in both normal and pathologic humeral anatomy. Glenoid malpositioning can lead to both humeral instability and increased stress of the glenoid component that may lead to premature glenoid loosening.

Healing of reamed glenoid bone articulating with a metal humeral hemiarthroplasty: a canine model.

This study characterizes the healing response of the glenoid after spherical reaming and prosthetic humeral head replacement in a canine model of glenohumeral hemiarthroplasty. The right glenoid of twelve skeletally mature female dogs was reamed to a uniform radius of curvature, removing all cartilage down to bleeding subchondral bone. The glenoid was not resurfaced.