Reversing the position of ball & socket of the shoulder joint(a ball & socket type of joint) when doing total joint replacement is Reverse shoulder Arthroplasty.
A conventional shoulder arthroplasty mimics the normal anatomy of the shoulder: a “cup-prosthesis” fitted into the glenoid, and a “head-prosthesis” is attached to the top of humerus. In a reverse shoulder replacement, the socket and ball(head) are switched. The metal ball is fixed to the glenoid and the plastic cup is fixed to the upper end of the humerus.
- Cuff-tear arthropathy
- Massive rotator cuff tear with pseudoparalysis
- Severe inflammatory arthritis with a massive cuff tear
- Failed shoulder arthroplasty:-
->Absence of tuberosities (failed hemiarthroplasty for fracture/nonunion)
->Absence of cuff (failed hemiarthroplasty for cuff-tear arthropathy)
- Proximal humeral fracture
- Proximal humeral nonunion
- Reimplantation for deep periprosthetic infection
- Reconstruction after tumor removal
- Contraindications:- 1. loss or inactivity of deltoid, 2. Excessive glenoid bone loss-no secure implantation of glenoid component, 3. Younger patients, 4. Surgeon Inexperience- a relative contraindication.
- Biomechanism:- ~Reverse prosthesis works by changing the direction of pull of the deltoid.
~With standard prosthesis, humeral head subluxate superiorly due deltoid contraction in the absence of rotator cuff
~Reverse prosthesis corrects the subluxation by placing the centre of rotation of arm laterally & re-estabilishing a fulcrum around which the deltoid-pull can restore forward elevation.