Construction Worker Diagnosed with Rare Milwaukee Shoulder Syndrome After Joint Destruction

A 45-year-old construction worker went to the emergency department for his right shoulder, which was extremely swollen and becoming progressively more painful. Doctors took an X-ray to try to see what was causing the problem. But when the images came through, it was what they didn’t see that explained the situation: His entire shoulder joint was gone, seemingly blasted apart into small, lingering pieces.

The shoulder joint is a ball-and-socket joint, with the sphere-like head of the upper arm bone (humerus) sitting in the socket of the shoulder blade. According to a case report in the New England Journal of Medicine, the man’s X-ray showed that he no longer had a ball at all or an intact socket. His upper arm bone was detached from the joint, and the sphere-like top of his upper arm bone (humeral head) was completely gone. The broken, headless humerus was instead left to float freely in the man’s arm, unattached to his upper body.

Magnetic resonance imaging, meanwhile, found that the man’s rotator cuff—the group of muscles and tendons that holds the upper arm firmly in the socket—was also destroyed. Three of the four main tendons (supraspinatus, infraspinatus, and subscapularis tendons) had full-thickness tears.

The doctors diagnosed the man with a rare, ruinous condition called “Milwaukee Shoulder Syndrome” or MSS. The term was coined in 1981 based on the cases of four elderly women in Wisconsin who, like the man, had severe destruction of their shoulder joints and massive tears to their rotator cuffs. The condition is similar to—and possibly a subtype of—rapid destructive arthritis, which was identified a year later in 1982.

Despite being identified decades ago, the exact trigger of the joint-demolishing condition is still unclear. But doctors have hypothesized a series of events that leads to the disintegration. The hallmark of MSS is the deposition of calcium-containing crystals, specifically hydroxyapatite crystals, in the joint. These crystals may spur the production of enzymes that can attack and destroy tissues around the joint, including the rotator cuff. The attack is followed by inflammation and swelling that together cause damage that snowballs to complete joint destruction, which can progress rapidly. In the man’s case, he said his shoulder pain had mounted over just two months.

MSS is most often seen in women and has been linked to prior shoulder trauma and surgeries. It’s unclear why the middle-aged man in this case had the misfortune of developing it, but his doctors noted he had a pre-existing rotator cuff injury, and his work in construction put him at higher risk.

When caught early, MSS may be treated conservatively with anti-inflammatory medications and sometimes colchicine, a treatment for gout. But for a case as bad as the man’s, the main treatment is a full shoulder replacement. His doctors in the emergency department gave him pain and anti-inflammatory medication and referred him for a surgery evaluation.