Moeckel and colleagues reviewed why shoulders became unstable after replacement arthroplasty and how anterior and posterior instability were treated.
Retrospective review of 10 patients drawn from 236 shoulder replacements done at Hospital for Special Surgery (1984 to 1989), each followed at least 2 years.
Methods
Design
Retrospective case series
Patients
10 unstable shoulders among 236 arthroplasties
8 women and 2 men
Aged 56 to 79 years
Anterior instability in 7
Posterior instability in 3
Treatment
Anterior: subscapularis mobilized and repaired, with an Achilles tendon allograft if instability persisted
Posterior: soft‑tissue rebalancing, with component revision when needed
Follow-up
Minimum 2 years, maximum 5 years
Outcomes
Stability after operative treatment
Motion compared with before the dislocation
Complications
Key Findings
Anterior or posterior instability developed in 10 of 236 shoulder replacements, anterior in 7 and posterior in 3, with isolated superior subluxation from cuff deficiency excluded.
Four anterior dislocations happened 3 to 7 weeks after surgery, usually in physical therapy, during passive external rotation.
Repeat subscapularis repair stabilized 4 of the 7 anterior shoulders, and the other 3, whose tendon and capsule were too scarred and shortened to repair, were stabilized with a bone‑Achilles tendon allograft.
One posterior dislocation was attributed to component malposition, with the humeral component in 70° of retroversion.
Revision stabilized 2 of the 3 posterior shoulders, while instability recurred in a paraplegic patient once she resumed using the arm to operate a wheelchair, and her components were later removed.
Every patient ended with less motion than before the dislocation, and there were no neurovascular, allograft or other complications.
Board pearl
In this series, every anterior instability after shoulder arthroplasty traced back to rupture of the repaired subscapularis tendon.
Authors' conclusion
We concluded that proper balancing of the soft tissues and positioning of the prosthetic components are essential to a successful arthroplasty of the shoulder. The postoperative rehabilitation should include a physical therapy program in which the range of motion of the arm that was achieved in the operating room is not exceeded.
Moeckel and colleagues reviewed why shoulders became unstable after replacement arthroplasty and how anterior and posterior instability were treated.
Retrospective review of 10 patients drawn from 236 shoulder replacements done at Hospital for Special Surgery (1984 to 1989), each followed at least 2 years.
Methods
Design
Retrospective case series
Patients
10 unstable shoulders among 236 arthroplasties
8 women and 2 men
Aged 56 to 79 years
Anterior instability in 7
Posterior instability in 3
Treatment
Anterior: subscapularis mobilized and repaired, with an Achilles tendon allograft if instability persisted
Posterior: soft‑tissue rebalancing, with component revision when needed
Follow-up
Minimum 2 years, maximum 5 years
Outcomes
Stability after operative treatment
Motion compared with before the dislocation
Complications
Key Findings
Anterior or posterior instability developed in 10 of 236 shoulder replacements, anterior in 7 and posterior in 3, with isolated superior subluxation from cuff deficiency excluded.
Four anterior dislocations happened 3 to 7 weeks after surgery, usually in physical therapy, during passive external rotation.
Repeat subscapularis repair stabilized 4 of the 7 anterior shoulders, and the other 3, whose tendon and capsule were too scarred and shortened to repair, were stabilized with a bone‑Achilles tendon allograft.
One posterior dislocation was attributed to component malposition, with the humeral component in 70° of retroversion.
Revision stabilized 2 of the 3 posterior shoulders, while instability recurred in a paraplegic patient once she resumed using the arm to operate a wheelchair, and her components were later removed.
Every patient ended with less motion than before the dislocation, and there were no neurovascular, allograft or other complications.
Board pearl
In this series, every anterior instability after shoulder arthroplasty traced back to rupture of the repaired subscapularis tendon.
Authors' conclusion
We concluded that proper balancing of the soft tissues and positioning of the prosthetic components are essential to a successful arthroplasty of the shoulder. The postoperative rehabilitation should include a physical therapy program in which the range of motion of the arm that was achieved in the operating room is not exceeded.