• Internal shoulder impingement is characterized by soft tissue compression between the glenoid and humerus, often occurring in abduction and external rotation positions.
• Unlike external impingement, it involves the rotator cuff and joint capsule within the shoulder, leading to symptoms and potential imaging findings like partial cuff tears and labral pathology.

• Mostly observed in younger individuals under 40, especially athletes engaging in repetitive overhead activities.
• Less common in non-athletes but can affect anyone engaging in activities requiring extensive shoulder rotation and abduction.

• Symptoms include chronic posterior shoulder pain exacerbated by specific shoulder movements.
• Decrease in throwing velocity or performance in athletes may be noted.

• Posterior joint tenderness
• GIRD (glenohumeral internal rotation deficit), and
• Instability signs, though anterior instability with internal impingement is less common.
• The Posterior Impingement Sign test, with high sensitivity and specificity, is crucial for diagnosis.
• MRI and arthrography can help identify related structural changes.

• Focuses on non-operative management initially, including rest, stretching of the posterior capsule
• Rehabilitation exercises targeting:
  • Acquired instability
  • GIRD by exercises such as the Sleeper’s stretch and Cross-body stretch
  • Scapular dyskinesis focusing on scapular retraction and stabilization
  • Surgical intervention is considered for cases not responding to conservative management.

Cools, A. M., Declercq, G., Cagnie, B., Cambier, D., & Witvrouw, E. (2008). Internal impingement in the tennis player: rehabilitation guidelines. British journal of sports medicine, 42(3), 165-171.

Corpus, K. T., Camp, C. L., Dines, D. M., Altchek, D. W., & Dines, J. S. (2016). Evaluation and treatment of internal impingement of the shoulder in overhead athletes. World Journal of Orthopedics, 7(12), 776.

Leschinger, T., Wallraff, C., Müller, D., Hackenbroch, M., Bovenschulte, H., & Siewe, J. (2017). Internal impingement of the shoulder: a risk of false positive test outcomes in external impingement tests?. BioMed Research International, 2017.

Meister, K., Buckley, B., & Batts, J. (2004). The posterior impingement sign: diagnosis of rotator cuff and posterior labral tears secondary to internal impingement in overhand athletes. American journal of orthopedics (Belle Mead, NJ), 33(8), 412-415.

Spiegl, U. J., Warth, R. J., & Millett, P. J. (2014). Symptomatic internal impingement of the shoulder in overhead athletes. Sports medicine and arthroscopy review, 22(2), 120-129.