Posterior Internal Impingement Test

The Posterior Internal Impingement Test is a crucial diagnostic tool in the assessment of shoulder Posterior Internal Impingement, particularly in overhead athletes.

Posterior internal impingement occurs when the undersurface of the rotator cuff contacts and compresses against the posterosuperior glenoid rim and labrum. This patho-mechanical condition primarily manifests during shoulder abduction combined with external rotation.

Patients typically present with posterior shoulder pain during the late cocking and early acceleration phases of throwing activities. This symptom pattern reflects the biomechanical stress placed on the posterior shoulder structures during these movement phases.

See Also: Neer Test

How to perform the Posterior Internal Impingement Test?

The examining clinician should position the patient supine on the examination table. The shoulder is then passively moved into 90 to 110 degrees of abduction, combined with 15 to 20 degrees of extension beyond the coronal plane. The final component involves maximum external rotation of the shoulder.

What does a positive test mean?

A positive Posterior Internal Impingement Test is indicated by the reproduction of localized posterior shoulder pain that matches the patient’s symptomatic complaints. The pain typically mirrors the discomfort experienced during athletic activities, particularly in the late cocking phase of throwing.

Posterior internal impingement frequently occurs in conjunction with other shoulder pathologies. Common associations include anterior instability or pseudolaxity of the glenohumeral joint. Additionally, compensatory increased deltoid activity often develops in response to rotator cuff weakness.

See Also: Shoulder Range of Motion

Differential Diagnosis

There are several differential diagnoses when evaluating posterior shoulder pain. The presentation may mimic other conditions such as posterior labral tears, rotator cuff tendinopathy, or scapular dyskinesis. Therefore, comprehensive clinical examination and appropriate imaging studies may be necessary for definitive diagnosis.

References & More

1. Magee DJ. Orthopedic Physical Assessment. 7th ed. St. Louis, MO: Elsevier; 2020. [https://www.elsevier.com/books/orthopedic-physical-assessment/magee/978-0-323-67262-5]
2. Meister K. Injuries to the shoulder in the throwing athlete. Part II: evaluation/treatment. Am J Sports Med. 2000;28:587–601. Pubmed
3. Davidson PA, Elattrache NS, Jobe CM, et al. Rotator cuff and posterior-superior glenoid labrum injury associated with increased glenohumeral motion: a new site of impingement. J Shoulder Elbow Surg. 1995;4:384–390. Pubmed