Background
- In patients with rotator cuff arthropathy, a "reverse"
shoulder prosthesis resists glenohumeral subluxation
and offers the potential for improved function.
- Premature mechanical failure due to loosening of the
glenoid component is a concern with these devices,
especially when used in revision shoulder arthroplasty
and in patients with less-than-optimal bone stock, as
some reverse shoulder prosthesis have increased lateral
offset at the glenohumeral articulation with potentially
greater loads transferred to the bone-prosthesis interface.
- The potential clinical advantages for using an increased
offset reverse shoulder prosthesis, such as enhanced
stability and function, can only be realized if satisfactory
glenoid component fixation is achieved.
In-Vitro Study
- In-vitro study evaluated initial glenoid component fixation
of 2 uncemented "reverse" prostheses during physiologic loading to determine the relationship
among lateral offset of the glenosphere, fixation method,
and motion.
Results
- Both lateral offset and peripheral screw type affected
the magnitude of baseplate motion.
- Baseplate motion for Delta III components and Reverse® Shoulder Prosthesis components fixed with 5.0mm
captured screws were below the 150 μm of motion
generally accepted as the threshold for bone ingrowth.
- Stable fixation was achieved for the Reverse Shoulder Shoulder
Prosthesis neutral components despite a substantially
(69%) greater moment at the baseplate-foam interface
compared with the Delta III.
Herman M, Frankle M, Vasey M, Banks S. Intial Glenoid Component Fixation
in “Reverse” Total Shoudler Arthroplasty: A Biomechanical Evalutation.
Journal Shoulder Elbow Surgery. 2005 Jan/Feb; 14(15): 1625-1675
