Body Mass Index (BMI) Effects on the Sensitivity and Specificity of the Physical Examination of the Shoulder

Background: The physical examination of the shoulder of overweight patients could be quite challenging. The reliability of provocative tests of the shoulder in this growing patient population has yet to be established. The purpose of our study was to assess whether body mass index (BMI) effect the sensitivity and specificity of common shoulder tests, using arthroscopy as a gold standard.

Methods: We reviewed data of consecutive patients who underwent shoulder arthroscopy for the treatment of rotator cuff tears, Bankart lesions and superior labral anterior—posterior (SLAP) lesions between 2013-2016. Physical examination of the shoulder and the patient`s BMI were documented prior to surgery. Statistical analysis was performed in order to evaluate sensitivity and specificity of provocative tests of the shoulder and their relationship with the patients` BMI.

Results: A Bankart lesion was present in 43 patients during arthroscopy. Sensitivity and specificity of the apprehension, relocation and drawer tests were greater in patients with BMI>25 (area under curve (AUC)=0.01, 0.02 and 0.004, respectively). A supraspinatus tear (SSP tear) was present in 57 patients during arthroscopy. Provocative tests for SSP tear in patients with BMI>25 tended to be more sensitive and less specific, however the AUC of these tests was not statistically significant. A SLAP lesion was present in 72 patients. There was no statistically significant difference in sensitivity and specificity of provocative tests for SLAP lesion between patients over and under a BMI of 25.

Conclusion: It appears BMI has an impact on the sensitivity and specificity of provocative tests for shoulder instability and perhaps also for tests evaluating rotator cuff pathology. The physician should be alert when examining the overweight patient as these effects maybe counterintuitive.