Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Shoulder Labral Tears and Instability

Key Points

  • The goal of therapeutic approaches to glenohumeral joint instability is the restoration of anatomy.
  • The glenohumeral joint is inherently unstable, with the large humeral head articulating with the small and shallow glenoid.
  • The labrum acts as the anchor point for the capsuloligamentous structures, increases the depth of the glenoid socket, and facilitates the concavity-compression mechanism as the humeral head is compressed in the glenoid during rotator cuff contraction.
  • Bankart lesions have been considered the primary pathology leading to recurrent anterior dislocation. These lesions were originally described as injuries to the labrum corresponding to the detachment of the anchoring point of the inferior glenohumeral (IGHL) and middle glenohumeral (MGHL) ligaments from the glenoid rim.
  • Traumatic intra-substance injury of the joint capsule is commonly associated with anterior dislocation. Depending on the magnitude of the anterior shear force, either plastic deformation or a complete tear of the joint capsule can occur.
  • The most common bony lesion associated with traumatic glenohumeral instability is a compression fracture at the posterolateral margin of the humeral head. Commonly known as a Hill-Sachs lesion, this fracture occurs as the humeral head impacts the glenoid edge during dislocation.
  • Shoulder instability is categorized on the basis of four criteria: frequency, etiology, degree, and direction.
  • The degree of instability–dislocation, subluxation, or microinstability–is also important in determining appropriate treatment options.
  • Many athletes with ligamentous laxity have instability that is primarily posterior in nature. These patients suffer recurrent posterior subluxation and have a history of posterior shoulder pain rather than complaints of rank instability.
  • A true anteroposterior (AP) view with an axillary lateral view is the minimum radiographic workup necessary for evaluation of an acute dislocation or suspected subluxation.
  • The goal of treatment in both open and arthroscopic surgery is to restore the labrum to its anatomic attachment site and to establish the appropriate tension to the inferior capsuloligamentous complex of the joint.
  • Interscalene regional blockade has been effective in providing early postoperative pain relief and in decreasing overall narcotic requirements following surgery.
  • Strong indications for open stabilization procedures include significant degrees of glenoid or humeral bone loss, capsular deficiencies, or irreparable rotator cuff tears, particularly those of the subscapularis. In individuals with significant anterior glenoid erosion, an osseous reconstruction should be performed.
  • Revision instability surgery is the most technically challenging of all open shoulder surgery. When attempting to salvage failed anterior instability cases, surgeons should be prepared to face challenging scenarios such as distorted anatomic tissue planes, severe scarring, capsular deficiencies from multiple prior surgeries or thermal capsulorrhaphy, bony deficiencies due to erosion or fracture, and subscapularis deficiencies.

The treatment of shoulder instability has evolved rapidly in recent years due to a better understanding of shoulder biomechanics and pathoanatomy, advancements in imaging technology, and improvements in surgical implants and techniques.

The goal of contemporary therapeutic approaches to glenohumeral joint instability is the restoration of anatomy. This requires a thorough and clear understanding of the anatomy and biomechanics of the glenohumeral articulation.

This chapter will summarize the relevant basic science, evaluation, and treatment of patients with labral pathology with an emphasis on shoulder instability, including discussion of those rare patients with instability secondary to bony abnormalities or posterior labral pathology. This chapter will also include a section on special considerations in revision surgery for failed stabilization procedures, complications, and future directions.

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