Adhesive Capsulitis (Frozen Shoulder) Workup

Updated: Jul 21, 2022
  • Author: Jefferson R Roberts, MD; Chief Editor: Herbert S Diamond, MD  more...
  • Print

Approach Considerations

Frozen shoulder syndrome (FSS) is a clinical diagnosis. Laboratory and imaging studies can be used to rule out other conditions and to confirm the likelihood of the correct diagnosis. Accurate diagnosis is essential because the treatment for FSS differs from the treatment for other shoulder entities. 


Laboratory Studies

Laboratory studies rarely are required for the evaluation of adhesive capsulitis. However, if a predisposing medical condition that may be contributing to adhesive capsulitis is suggested, the following tests may be ordered:

  • Complete blood cell count (CBC)
  • Erythrocyte sedimentation rate (ESR)
  • C-reactive protein (CRP)
  • Blood glucose
  • Hemoglobin A1c 
  • Thyroid-stimulating hormone (TSH)
  • Free thyroxine index (FTI)
  • Free thyroxine (FT4)

Although an orthopedic surgeon may order these tests, results should be forwarded to the patient's primary care physician for further evaluation.


Imaging Studies

Imaging studies are not indicated in the diagnosis of FSS. No imaging modality has been definitively shown to provide greater diagnostic value, due to the heterogeneity of techniques used, and the presence of potential confounding factors limits definitive conclusions from imaging study findings. However, more recent studies are moving toward defining the criteria for imaging studies to aid in the staging of FSS. Common findings in FSS are thickening of the coracohumeral and inferior glenohumeral ligaments. Zappia et al notes that imaging may be used to exclude articular or rotator cuff pathology, that thickening of the coracohumeral and inferior glenohumeral ligaments are common findings in FSS, and that rotator interval fat pad obliteration has 100% specificity for adhesive capsulitis. [42]


Routine radiographs do not have a role in the diagnosis of FSS. However, plain films of the shoulder should be obtained in all cases to rule out any other pathologic process. These radiographs should include the following [43] :

  • Anteroposterior (AP) view of the glenohumeral joint in neutral rotation
  • Supraspinatus outlet view
  • Axillary lateral view (if possible)


Ultrasound (regular and Doppler) for the diagnosis of FSS remains controversial. Overall, these studies have shown utility for measurement of acohumeral ligament thickness and presence of a hypoechoid region with increased vascularity in the rotator interval, with fibrovascular inflammatory tissue. 


Arthrography, which involves intra-articular injection of diluted iodinated contrast medium, can aid in both the diagnosis and treatment of FSS. The following findings are suggestive of FSS [42] :

  • Reduced capsular distention, with irregular internal profile and internal septa (medial leakage of contrast)
  • Lack of distention of subscapular bursa
  • Atypical contrast leakage in the biceps sheath

Milena et al report that the findings on computed tomography (CT) arthrography are comparable to those on magnetic resonance imaging (MRI). Diagnostic signs are decreased width of the axillary recess and thickening of the lateral wall. [44]

Positron emission tomography/computed tomography

Duchstein et al suggest that 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) may have a role in diagnostically challenging cases, such as distinguishing the first phase of frozen shoulder from subacromial impingement. Their study in 20 patients, found that, in general, patients with frozen shoulder showed increased FDG uptake in the affected shoulder regions, whereas those with subacromial impingement showed no uptake. Combining visual assessment with semi-quantified analysis resulted in sensitivity of 100% and specificity of 93% for the distinction between the two disorders. [45]

Magnetic resonance imaging

MRI is not initially indicated in cases of FSS. However, if the patient does not improve after a period of time (6 weeks to 3 months), then MRI is appropriate to rule out a possible rotator cuff tear or intra-articular pathology. [46, 47]  Chi et al concluded that non-contrast MRI (ie, without direct MRI arthrography), in conjunction with clinical criteria, can support accurate diagnosis of FSS. [48] However, a study by Erber et al found that the addition of contrast-enhanced sequences can significantly increase the sensitivity of MRI for this diagnosis. [49]

A 2018 systematic review and meta-analysis identified six features on non-arthrogram MRI that may be used to diagnose FSS, as follows [50] :

  • Coracohumeral ligament thickening (diagnostic odds ratio [DOR] 13)
  • Fat obliteration of the rotator interval (DOR 8)
  • Rotator interval enhancement (DOR 44; sensitivity and specificity > 80%)
  • Axillary joint capsule enhancement (DOR 52; sensitivity and specificity > 80%)
  • Inferior glenohumeral ligament hyperintensity (DOR 31)
  • Inferior glenohumeral ligament thickening (DOR 28)

Zappia et al hypothesize that the high pericapsular signal intensity corresponds to hypervascular synovitis during the frozen phase of FSS. [42]  Park et al have correlated MRI findings with the clinical stage of FSS; see Table 2, below. [51]

Table 2 MRI findings according to clinical stage of FSS (Open Table in a new window)

Stage Joint capsular thickness (mm) in humeral portion of the axillary access Joint capsule edema  in humeral portion of axillary recess Obliteration of subcoracoid fat triangle
1 4.67 97% 74%
2 3.73 83% 56%
3 3.67 64% 21%

Histologic Findings

Common arthroscopic findings in patients with adhesive capsulitis are the following:

  • Proliferative synovitis
  • Capsular and intra-articular subscapularis tendon thickening
  • Fibrosis
  • Chronic inflammatory cells

Significant synovitis is noted mostly in the anterior capsule, but is not limited to that area. In addition, most patients demonstrate significant subacromial fibrosis. One study found that approximately 40% of patients had significant subacromial fibrosis, regardless of preoperative etiology.