Milwaukee Shoulder

Abstract

Milwaukee Shoulder Syndrome (MSS) is a rapidly progressive and destructive arthropathy that affects the glenohumeral joint and the rotator cuff.

The pathomechanism is not understood as of yet. However, it is speculated that calcium hydroxyapatite crystals are released into the joint, which leads to phagocytosis and release of destructive collagenase and active protease.

MSS imposes as a painful shoulder with limited active and passive range of motion.

Diagnosis is primarily made by obtaining synovial fluid and the analysis of the same

Current treatment modalities are symptomatic and supportive. Therefore, intraarticular steroid injection, administration of NSAIDs and subsequent physical therapy are indicated.

General considerations

Definition

Milwaukee Shoulder Syndrome (MSS) is a rapidly progressive and destructive arthropathy that affects the glenohumeral joint and the rotator cuff. It is characterised by non-inflammatory joint effusion containing calcium hydroxyapatite crystals and multiple osteochondral loose bodies.

Aetiology

The exact formation process of crystals in the glenohumeral joint are not understood yet. However, it is hypothesised that calcium hydroxyapatite crystals form in degenerative cartilage tissue and are released into the joint [1]. Phagocytosis of those crystals by synovial cells is believed to initiate the release of collagenase and active protease, which in return further damage the cartilage and rotator cuff, leading to an additional release of those enzymes [1]. The newly created vicious cycle consequently leads to the massive destruction that is seen in MSS.

Additionally, certain factors have been identified which predispose towards developing MSS such as recent trauma, joint overuse, pyrophosphate deposition, neuroarthropathy, dialysis and hyperparathyroidism [1].

Epidemiology

Altogether, Milwaukee shoulder syndrome is a rare disease. Exact data on the prevalence is inexistent. Yet, MSS affects women ranging from 50 to 90 years old more frequently and both shoulders are affected in 64% of cases with the dominant one involved more often [1]. Moreover, the knees are affected in 50%, especially the patellofemoral ad lateral tibiofemoral compartments [1, 2].

Clinical presentation

Clinically, MSS imposes as a painful shoulder with limited active and passive range of motion [1, 2]. Some cases also report on excessively mobile glenohumeral joints [1]. Most patients present with swelling due to effusion and complete tears of the rotator cuff are commonly observed [1]. As mentioned before, 50% of patients also present with similar symptoms in the knee joint.

Diagnosis

History

The examiner should inquire about the onset of symptoms as MSS is a rapidly progressive disease. In addition, one should inquire about predisposing factors and other signs suggestive of other pathologies as a Milwaukee Shoulder is a rare condition.

Disease specific diagnosis

Diagnosis is primarily made by obtaining synovial fluid and the analysis of the same [1, 2]. It shows a serohematic fluid with low cellularity [2]. Calcium hydroxyapatite crystals are made visible by alizarin red staining [1, 2].

Additionally, Ultrasound, Radiographs and MRI are performed. Signs suggestive of MSS are:

  • Ultrasound

      • Visualisation of calcific foci

      • Visualisation of joint effusion

      • Detection of rotator cuff tears

  • Radiograph

      • Glenohumeral joint space narrowing with little to no osteophytosis

      • Cranial subluxation of the humeral head, commonly with pseudoarthrosis with the acromion and distal clavicle

      • Subchondral sclerosis with cyst formation in the humeral head

      • Destruction of subchondral bone with partial bony collapse of the head

      • Intra-articular loose bodies

  • MRI

      • Large joint effusion

      • Tears of the rotator cuff

      • Narrowing of the glenohumeral joint

      • Thinning of the cartilage

      • Destruction of the subchondral bone

Differential diagnosis

  • Neuropathic arthropathy (frequently associated with syringomyelia)

  • Avascular necrosis

  • Dialysis arthropathy

  • Rheumatoid arthritis

  • Septic arthritis

X-ray in ap-view of patient with Milwaukee-Shoulder-Syndrome; Case courtesy of Dr Andrew Dixon, From the case https://radiopaedia.org/cases/62681

Treatment

Current treatment modalities are symptomatic and supportive. Therefore, intraarticular steroid injection, administration of NSAIDs and subsequent physical therapy are indicated [1, 2].

Arthroplasty may be tried in some cases. However, MSS not rarely leads to massive destruction of the joint, rendering the arthroplasty technically challenging [1].

Prognosis and progressive course of disease

As data on the subject is very scarce, no prognosis can be made.

References

  1. Dewachter, L, P Aerts, I Crevits, and R De Manelfe. 2012. "Milwaukee Shoulder Syndrome.". Journal Of The Belgian Society Of Radiology 95 (4): 243-244. doi:10.5334/jbr-btr.629.

  2. Santiago, T., M. Coutinho, A. Malcata, and J. A. P. da Silva. 2014. "Milwaukee Shoulder (And Knee) Syndrome". Case Reports 2014 (may14 4): 1-3. doi:10.1136/bcr-2013-202183.