Shoulder Replacement 2 Flashcards
What is the most common design of constrained shoulder replacements?
ball-in-socket designs
What two types of ball-in-socket design are used?
regular anatomy
reversed anatomy
What is unusual about the Stanmore design?
metal on metal
What are some complications of the Stanmore design?
unsnapping of the components
instability
glenoid loosening
What is the reese TSR made from
cobalt chrome humeral head and a polyethylene socket within a metal glenoid cup
Why is the Reese prosthesis designed to dislocate when a specified large moment is reached?
to prevent fracture of the scapula
What restricts ROM in constrained designs?
impingement of the humeral component
what is unusual about the trispherical design?
it has 3 balls, not one
Describe the trispherical design
Both the humeral and glenoid components of the Trispherical prostheses have a metal ball, both of which are contained within a third larger polyethylene ball (which is encapsulated with a Vitallium shell for extra strength).
What advantages does the trispherical design have?
greater ROM and avoids impingement
What acts as constraint in the trispherical design?
surrounding soft tissues
Which has a higher rate of loosening and dislocation, unconstrained/constrained?
constrained
what methods have been used to try and fix glenoid components?
extended keel pegs stem wedge a large screw flanges
What desirable features does the Neer designed glenoid fossa have?
optional metal backed glenoid components which are thought to increase fixation and aid stress distribution
Name a shoulder replacement which attaches via a keel to the glenoid
trispherical
