A 45-year-old construction worker who came to an emergency department with a worsening swollen shoulder was diagnosed with Milwaukee shoulder syndrome after imaging showed the joint had been wrecked to an unusual degree, according to a case report in the New England Journal of Medicine.
The man had increasing pain and severe swelling in his right shoulder. Doctors ordered an X-ray to look for the cause. The striking finding was the absence of normal anatomy: the rounded top of the upper arm bone, called the humeral head, was gone, and the shoulder socket was no longer intact.
In a healthy shoulder, the humeral head sits in a socket in the shoulder blade, making a ball-and-socket joint. In this case, the report said, the upper arm bone was no longer connected to the joint. The remaining humerus was effectively left without its usual attachment to the shoulder.
Magnetic resonance imaging showed more damage around the same joint. The man’s rotator cuff, the set of muscles and tendons that helps keep the upper arm seated in the shoulder socket, was also badly injured. Three of the four major tendons named in the report, the supraspinatus, infraspinatus and subscapularis, had full-thickness tears.
What is Milwaukee shoulder syndrome?
Milwaukee shoulder syndrome is a rare destructive joint condition associated with severe shoulder breakdown and large rotator cuff tears. The name was introduced in 1981 after doctors described four elderly women in Wisconsin with similar joint destruction, according to the medical literature cited in the case report.
The condition resembles rapid destructive arthritis, which was identified in 1982, and may be a subtype of it. Decades after the syndrome was named, doctors still have not pinned down the exact trigger. That is a useful reminder that medicine contains plenty of named conditions whose mechanisms remain only partly mapped.
The suspected process centers on deposits of calcium-containing hydroxyapatite crystals inside the joint. Doctors have proposed that those crystals may help drive production of enzymes that damage nearby tissue, including the rotator cuff. Inflammation and swelling can then add to the injury, with the damage accelerating until the joint is destroyed.
The pace can be fast. The man in the NEJM report said his shoulder pain had been getting worse over two months.
Who gets Milwaukee shoulder syndrome?
The syndrome is reported more often in women and has been associated with earlier shoulder trauma and shoulder operations. The case report did not identify a clear reason this 45-year-old man developed it, but his doctors noted two relevant factors: he already had a rotator cuff injury, and his construction work placed him at higher risk for shoulder problems.
Treatment depends on how early the condition is found and how much destruction has occurred. The report said milder or earlier cases may be managed with anti-inflammatory drugs and sometimes colchicine, a drug also used for gout.
That was not the situation here. For severe destruction like the man’s, the main treatment described is total shoulder replacement. Emergency department doctors gave him pain medicine and anti-inflammatory medication, then referred him for a surgical evaluation.
This story draws on original reporting from Ars Technica.
