Summary Internal impingement is a cause of shoulder pain in overhead athletes caused by repetitive impingement between the undersurface of the rotator cuff and the posterosuperior glenoid. Diagnosis is made clinically with worsening posterior shoulder pain during maximal abduction and external rotation (position of late cocking) associated with decreased internal rotation and supplemented with MRI showing posterior rotator cuff and posterior labral pathology. Treatment with physical therapy and posterior capsule stretching is effective for most patients. Arthroscopic surgery is indicated for patients who fail conservative management. Epidemiology Demographics major cause of shoulder pain in throwing and overhead athletes Etiology Pathophysiology mechanism impingement occurs during maximum arm abduction and external rotation during late cocking and early acceleration phases of throwing causes "peel-back" phenomenon of posterosuperior labrum by the biceps pathoanatomy caused by repetitive impingement of the posterior under-surface of the supraspinatus tendon and the posterior superior aspect of the glenoid pathologic micromotion of the humeral head allows the rotator cuff to become impinged between the humral head and glenoid. login to view 1 more bullet internal impingement covers a spectrum of injuries including login to view 4 more bullets etiology tightness of posterior band of IGHL anterior micro-instability Associated conditions associated with GIRD SLAP tears SICK scapula and dyskinesia Anatomy Glenohumeral joint anatomy Glenohumeral stability static restraints glenohumeral ligaments glenoid labrum articular congruity and version negative intraarticular pressure dynamic restraints rotator cuff muscles biceps periscapular muscles Rotator cuff primary function is dynamic stability and centering the humeral head within the glenoid via balancing the force couples about the glenohumeral joint in both coronal and transverse planes, creating a stable fulcrum coronal plane login to view 1 more bullet transverse plane login to view 1 more bullet the goal of treatment in rotator cuff tears is to restore this equilibrium in all planes Classification No formal classification scheme Presentation Symptoms shoulder pain, sometimes loalized posteriorly diffuse pain in posterior shoulder along the posterior deltoid shoulder pain worse with throwing login to view 1 more bullet Physical exam inspection may see retroversion of proximal humerus pain with palpation along infraspinatus ROM increased external rotation decreased internal rotation login to view 2 more bullets preservation of the total arc of motion strength often can demonstrate rotator cuff weakness provocative tests Whipple test login to view 3 more bullets Apprehension test login to view 3 more bullets Imaging Radiographs recommended views complete shoulder series findings usually unremarkable AP may show a Bennett lesion (exostosis of posteroinferior glenoid) MRI or MR arthrogram findings can show pathology of the rotator cuff and/or labral pathology login to view 2 more bullets optional views ABER positioning reproduces position of impingement showing dynamic process on the humerus and glenoid sides Treatment Nonoperative PT, cessation from throwing, posterior capsule stretching indications login to view 3 more bullets Operative arthroscopic debridement of rotator cuff and/or labrum indications login to view 5 more bullets Arthroscopic vs mini-open rotator cuff and/or labral repair indications login to view 2 more bullets Posterior capsule release vs anterior capsular stabilization indications login to view 1 more bullet Techniques PT, cessation from throwing, posterior capsule stretching cessation break from throwing until pain subsided, followed by supervised return to throwing focusing on proper mechanics therapy posterior capsular stretching program (i.e. sleeper stretches), rotator cuff strength balancing, scapular stabilization, kinetic chain coordination stretching for 6 months outcomes correlated with compliance to therapy regimen Arthroscopic debridement of rotator cuff tear and/or labrum diagnostic arthroscopy perform meticulous exam under anesthesia to assess range of motion diagnostic arthroscopy intra-articular and subacromial debridement arthroscopic shaver to debride loose tissue edges allows accelerated rehab and return to throwing shorter post-op immobilization time Arthroscopic vs mini-open rotator cuff repair approach arthroscopic has advantage of addressing labral and other intra-articular pathology acromioplasty bursectomy performed to visualize bursal-side of tendon acromioplasty is not indicated if no bursal-sided pathology seen cuff repair abrasive preparation of the greater tuberosity footprint portal of Wilmington usually necessary partial-thickness tears login to view 3 more bullets complete partial tear followed by anatomic repair technique login to view 1 more bullet labrum prepare glenoid rim and repair of unstable labral tear Posterior capsular release vs anterior stabilization posterior release done adjunctively with above procedures cautery wand or arthroscopic shaver to release synovium and capsular tissues risk of axillary nerve injury anterior stabilization done adjunctively with the above procedures capsular plication most common Complications Progression to full-thickness rotator cuff tear small risk of partial tears treated with debridement alone Delayed Rate of Return to Play worse rates following rotator cuff repairs in throwing athletes Axillary nerve injury at risk during posterior release at the inferior border of infraspinatus