Locked posterior shoulder dislocation is an uncommon condition and is associated with a reverse Hill-Sachs lesion in 50% of cases. The condition is likely to occur in cases of violent trauma, seizures, or electric shock. Unrecognized dislocation with humeral head fracture affects joint function and humeral head vascularity and may lead to chronic instability, osteonecrosis, and osteoarthritis.
Source: Pubmed