Special Tests: Acromioclavicular (AC) Joint Pathology

Special Tests Covered in this Lesson:

• Acromioclavicular (AC) Joint Test-item Cluster
  • Obrien's Active Compression Test
  • Cross-body (Passive Adduction) Test
  • Resisted Extension Test
• Screening Tool
  • Palpation (High Sensitivity)

Acromioclavicular joint (AC joint) pain may result from repetitive use injury or trauma. Repetitive use injuries may include AC joint arthritis or AC ligament inflammation, and relatively minor injuries may include AC joint strain and sprain (e.g. coracoclavicular ligament strain). More serious trauma can result in AC joint separation in which the distal clavicle (collar bone) separates from the acromion process of the scapula (shoulder blade). For an accurate diagnosis, AC joint pain must be differentiated from shoulder impingement syndrome, shoulder arthritis, and rotator cuff pathology (e.g. rotoator cuff tear). Clinical professionals (physical therapists, physical therapy assistants, chiropractors, occupational therapists, athletic trainers, etc.) should be aware of the signs and symptoms of AC joint dysfunction and the special tests that may aid in diagnosing and screening patients and clients. Most often AC joint dysfunction can be treated with exercise and interventions intended to improve lower cervical and thoracic mobility, scapular (shoulder blade) stabilizer activity, and reinforcement from a home exercise program.

Special Notes on AC Joint Special Tests:

• Simple Screen: Pain during palpation of the AC joint may be an effective screen. A study by McFarland et al. showed that AC joint palpation had 96% sensitivity (better than any other test), but 10% specificity. This implies that a negative test likely rules out AC joint dysfunction; however, a positive test can only imply a need for further testing (11).
• Identifying AC Joint Dysfunction: Two or more positive tests on the AC Joint Test-item Cluster only slightly increase likelihood ratios when compared to the Resisted Extension Test alone (25). This implies that adding the Resisted Extension Test to Obrien's Active Compression Test is likely sufficient, as the addition of a 3rd test (e.g. Cross-body (Passive Adduction) Test may not result in any additional increase in predictive value.

Brookbush Institute Recommendation

The Obrien's Active Compression Test is included in the Brookbush Institute's "Best of" Instability and Labral Pathology cluster, it is recommended that pain on the top of the shoulder during the Obrien's test results in the addition of the Resisted Extension Test to this cluster. Positive results for the Obrien's and Resisted Extension Test , in conjunction with negative results for the other tests in the cluster, would strongly imply that pain is the result of AC joint dysfunction.

Brookbush Institute's "Best of" Instability, Labral Pathology, and AC Joint Cluster

• Apprehension Test
• Jobe's Relocation Test
• Biceps Load 2
• Jerk Test
• Obrien's Active Compression Test
• Resisted Extension Test

For an Introduction to Special Tests:

• For an introduction to Special Tests including definitions of specific terminology, what special tests measure, accuracy (specificity, sensitivity, reliability, etc.), how we chose the tests in each special test course lessons, and best practice recommendations:
• Special Tests: Introduction

Courses covering Special Tests for the Shoulder Girdle

• Special Tests: Shoulder Impingement Syndrome (SIS)
• Special Tests: Rotator Cuff Pathology
• Special Tests: Acromioclavicular (AC) Joint Pathology
• Special Tests: Shoulder Instability (Apprehension) and Labrum Pathology