Active Compression Test (O'Brien's) Special Test
Orthopedic Physical Examination & Clinical Assessment Guide
What is it used for?
- Diagnosing SLAP Lesions or AC Joint pathology.
How to Perform
- Part 1: Flex shoulder 90°, adduct 10°, Internally Rotate (Thumb down). Apply downward force.
- Part 2: Externally Rotate (Palm up). Apply downward force.
Interpretation of Results
- Positive for SLAP: Deep joint pain in Part 1 that is relieved in Part 2.
- Positive for AC Joint: Superficial pain on top of the shoulder in Part 1.
Diagnostic Accuracy
- Sensitivity: 100%
- Specificity: 98%
Clinical Context & Limitations
The Active Compression Test (O'Brien's) should be considered as one component of a comprehensive musculoskeletal assessment. No single special test has perfect diagnostic accuracy; thus, clinical decision-making should integrate test results with patient-reported symptoms, mechanism of injury, functional impairment, and relevant imaging.
Clinicians should be aware of potential false-positive results in patients with pain sensitisation, muscle guarding, or poor relaxation. For the Shoulder region, combining the Active Compression Test (O'Brien's) with complementary examination tests significantly improves overall diagnostic confidence.
References
- Magee, D. J. (2021). Orthopedic Physical Assessment.
