The Thumb Test: A Simple Physical Examination Maneuver for the Diagnosis of Symptomatic Posterior Shoulder Instability

The Physical Examination of the Throwing Shoulder

In the first part of this 2 part series, we describe the comprehensive evaluation of the overhead throwing athlete's shoulder. The physical examination of the throwing shoulder requires a comprehensive knowledge and familiarity with anatomy, kinesiology, pathology, and unique sporting demands. The history, systematic basic examination, and special testing of the rotator cuff, biceps and superior labrum anterior and posterior lesions, instability and labral pathology, and scapular dyskinesia will be covered in this review.

Posterior shoulder instability

Posterior shoulder instability (PSI) is defined by dynamic, recurrent and symptomatic partial or total loss of posterior joint contact. Anatomic risk factors comprise ligament hyperlaxity, glenoid retroversion or dysplasia, and high horizontal acromial morphology. Associated anatomic lesions comprise labrum lesions, posterior glenoid erosion and/or fracture, and anterior humeral head notching. We distinguish two subcategories of PSI: functional and structural, respectively without and with anatomic lesions. In both categories, there may be anatomic risk factors. Clinically, functional PSI involves reproducible asymptomatic voluntary subluxation or sometimes reproducible involuntary subluxation. Functional PSI implicates impaired external-rotation rotator cuff and scapular stabilizer muscle activity. Treatment is non-operative, by rehabilitation and shoulder pace maker. Structural shoulder instability involves anatomic lesions, often due to iterative microtrauma; pain is the most frequent symptom. It usually concerns young athletic subjects, but the clinical forms of structural and of anterior shoulder instability are not superimposable. Treatment may be surgical; arthroscopic labrum repair is effective in the absence of significant bone lesions, whereas otherwise posterior bone block is the treatment of choice. Surgical treatment of scapular features underlying structural PSI is improved by 3D preoperative planning, cutting guides and dedicated internal fixation systems. LEVEL OF EVIDENCE: expert opinion.

Management of Bone Loss in Posterior Glenohumeral Shoulder Instability: Current Concepts

» Posterior glenohumeral instability is relatively uncommon compared with anterior instability, but is becoming an increasingly recognized and surgically managed shoulder pathology.» Soft-tissue stabilization alone may not be sufficient in patients who present with substantial bone loss to the posterior glenoid and/or the anterior humeral head.» For posterior glenoid defects, posterior glenoid osteoarticular augmentation can be used, and posterior glenoid opening wedge osteotomy can be considered in cases of posterior instability with pathologic retroversion.» For humeral head lesions, several surgical treatment options are available including subscapularis transposition into the humeral head defect, autograft or allograft reconstruction, humeral rotation osteotomy, and shoulder arthroplasty.

Posterior Shoulder Instability in Tennis Players: Aetiology, Classification, Assessment and Management

Background

Micro-traumatic posterior shoulder instability (PSI) is an often missed and misdiagnosed pathology presenting in tennis players. The aetiology of micro-traumatic PSI in tennis players is multifactorial, including congenital factors, loss of strength and motor control, and sport-specific repetitive microtrauma. Repetitive forces placed on the dominant shoulder, particularly combinations of flexion, horizontal adduction, and internal rotation contribute to the microtrauma. These positions are characteristic for kick serves, backhand volleys, and the follow-through phase of forehands and serves. The aim of this clinical commentary is to present an overview of the aetiology, classification, clinical presentation, and treatment of micro-traumatic PSI, with a particular focus on tennis players.

Level of Evidence

5.