Anatomical reconstruction of reverse hill-sachs lesions using the underpinning technique.

Posterior glenohumeral joint dislocation is an uncommon injury and is associated with bony and ligamentous disruption. It requires prompt diagnosis and early treatment to prevent acute or recurrent instability and subsequent dysfunction. Reverse Hill-Sachs lesions associated with this injury are challenging to treat, and optimal treatment is controversial. Treatment methods can be divided into those that achieve stability through muscle transfers, osteotomies, or posterior bone-block procedures (glenoid augmentation) and those that restore the sphericity of the humeral head. Joint replacement is often suggested for large head lesions (>50%) considered beyond reconstruction. Restoration of stability, preservation of the proximal humeral anatomy, and salvage of the humeral head sphericity should be the treatment goals in the younger population.This article describes the surgical technique of elevation of the impressed osteochondral fragment followed by filling the lesion with Allomatrix bone graft putty (Wright Medical Technology, Arlington, Tennessee) in 2 patients. The size of the head lesion was ≤35%. Underpinning raft screws were used to provide subchondral support and prevent the collapse of the elevated fragment. Postoperatively, the sphericity of the humeral head and glenohumeral stability were restored. No evidence of collapse, osteonecrosis, or osteoarthritis progression was seen at latest follow-up. Functional results were excellent, with a minimum follow-up of 2 years.This technique is an alternative method of restoring humeral head sphericity in patients with acute posterior glenohumeral joint dislocations with medium (20%-40%) reverse Hill-Sachs lesions.