Teaching Case

Patient with unremarkable previous history, complaining of right shoulder pain and limited joint mobility, no history of recent trauma. The pain started two months prior to her visit and was exacerbated by overhead activities.
On physical examination, the shoulder was swollen with signs of large intra-articular effusion.

X-rays and CT (Fig 1, 2) may reveal glenohumeral joint space narrowing and multiple irregularities of the humeral head, glenoid and acromion. In later stages, bone destruction may be almost complete, and intra-articular loose bodies are often identified.
On MRI (Fig. 3), extensive soft-tissue swelling can be demonstrated, associated with a complete rotator cuff tear resulting in upward migration of the humeral head. Large synovial proliferation with multiple capsular calcifications is usually present with a massive joint effusion. The bone and cartilage damage with subchondral cyst formation is easily detected.

Milwaukee shoulder syndrome (MSS) is a condition characterized by a rapidly progressive destructive arthropathy that mostly affects the shoulder in elderly women.
This entity is considered as a combination of: a complete rotator cuff tear with osteoarthritis changes, destruction of cartilage and subchondral bone, multiple osteochondral loose bodies and synovial hyperplasia with joint effusion containing calcium hydroxyapatite and calcium pyrophosphate dihydrate crystals [1, 2].
There is no scientific consensus about the aetiopathogenenesis of this disorder. The most accepted theory is the role of calcium pyrophosphate and hydroxyapatite crystal deposition in the joint, which causes arthropathy. It has been demonstrated that the crystals induce production of pro-inflammatory and catabolic mediators causing inflammatory response in cells (chondrocytes and synoviocytes), further synovitis, cartilage degradation and secondary bone destruction [1-3].
Most individuals with calcium pyrophosphate dihydrate crystal deposition disease are asymptomatic with respect to joint involvement, but in MSS the symptoms mainly respond to the complete rupture of the rotator cuff with widespread joint damage involving synovial membrane, cartilage and subchondral bone [4, 5].
Clinical presentation is non-specific and the symptoms overlap with those of a different entity, which is the reason why the imaging technique plays an important role in the diagnosis of Milwaukee shoulder and in excluding other possible causes. Patients often complain of shoulder pain and swelling with limited shoulder movement, without history of trauma. Usually a single large joint is affected with a high prevalence of shoulder, but the knee can also be involved [2-4].
Together with imaging techniques, arthrocentesis and analysis of joint fluid is required in order to assist in the final diagnosis.
Unfortunately, some radiological findings of MSS may be common to several diseases. In patients with a monoarticular destructive lesion, infection must be the first cause to rule out, extra-articular symptoms of infection, and laboratory tests (particularly isolation of germs from synovial fluid) confirm septic arthritis. Partial destruction of the humeral head can be seen in neuropathic arthropathy (Charcot), but typically the glenoid; acromion and tendons are not affected. Charcot is often associated with neurological disorders, e.g. syringomyelia and meningomyelocele; because of underlying loss of sensation usually the swelling is painless. In other entities such as: Osteonecrosis, rapidly destructive osteoarthritis and primary synovial osteochondromatosis, the rotator cuff remains intact [4].
The management of this condition is often problematic, ranging from symptomatic treatment to surgery with total arthroplasty. In our case total shoulder replacement arthroplasty was considered, but the patient refused surgery.