Description of the condition
The glenohumeral or shoulder joint is a ball-and-socket joint that consists of the head of the humerus (upper-arm bone) and the glenoid fossa, a shallow dish-shaped part of the scapula (shoulder blade). The shoulder joint has the greatest mobility of all joints in the body; this reflects the relative positioning, dimensions and mobility of its components, where mainly soft tissues (e.g. the rotator cuff tendons and the muscles linking the scapula to the thoracic cage) rather than bone act as restraints. In consequence, it is the most commonly dislocated joint in the body (Veeger 2011).
Shoulder or glenohumeral instability may be defined as the inability, during active shoulder movements, to maintain the humeral head within the shoulder joint or, more precisely, centred with the glenoid fossa of the scapula. Shoulder instability is a debilitating condition most often encountered in active young men; it can cause severe pain and disability, often leading to inability to work or participate in sports (Cadet 2010). The most common form of glenohumeral instability is said to be anterior (the humeral head is pushed out of the joint in a forward direction) or anteroinferior (forward and downwards), as up to 98% of instability cases have been reported to occur in these directions (Liu 1996). This results, in almost all cases, from a traumatic event such as a fall with the arm outstretched or a direct blow to the shoulder. These types of traumatic events cause partial dislocation (subluxation) or dislocation of the glenohumeral joint, leading to injuries to the shoulder joint structures. The overall incidence of traumatic shoulder dislocation has been reported to be 1.7% in the general population (Romeo 2001), and it accounts for 50% of all dislocations encountered in the emergency department (Blake 1999).
The most commonly injured structures, which are often stretched or torn, are the labrum (a fibrocartilaginous rim attached around the margin of the glenoid fossa of the shoulder blade), deep shoulder tendons of the rotator cuff and shoulder joint ligaments. The humeral head or the glenoid may also be fractured (Grumet 2010). Common pathoanatomy findings following traumatic anterior dislocation include a Bankart lesion and a torn labrum at the anteroinferior part of the glenoid (Grumet 2010). In more severe cases, a bony Bankart lesion may be present when the glenoid bone is broken off with the anterior labrum. A Hill-Sachs lesion may often be present at the posterior aspect of the humeral head. The Hill-Sachs lesion is an osseous defect caused by the impaction of the posterior humeral head on the anteroinferior labrum when the shoulder dislocates (Provencher 2012). Once these structures have been injured, the stability of the glenohumeral joint is compromised, in particular with dynamic movements of the arm in overhead positions. Up to 50% of people may experience recurrent episodes of subluxation or other episodes of dislocation subsequent to their initial traumatic dislocation (Robinson 2006).
There is still much debate regarding the best treatment for people suffering from anterior shoulder instability (Grumet 2010). Conservative (non-surgical) treatment typically comprises shoulder immobilisation in a sling followed by rehabilitation involving exercises to regain dynamic control of the humeral head and to strengthen the shoulder rotator cuff muscles. A Cochrane review has concluded that the effectiveness of different conservative management options for this population is uncertain (Handoll 2006). Emerging evidence suggests that, especially in young active patients, early surgical intervention to repair shoulder joint structures followed by immobilisation and rehabilitation may be more efficacious (Grumet 2010). The Cochrane review comparing surgical versus non-surgical management found that highly active young people treated surgically after an acute anterior shoulder dislocation were less likely to have an unstable shoulder (Handoll 2004).
Description of the intervention
There are two basic types of surgical approach for shoulders with post-traumatic anterior instability: ‘anatomic’ (anatomical) and ‘non-anatomic’ (non-anatomical) repairs.
Anatomic repairs, which aim to restore normal anatomy, involve the repair of damaged structures, such as a Bankart lesion, and repair or reconstruction of damaged capsule and torn ligaments. Thus the aim of a typical Bankart repair procedure is to reattach the torn labrum to the anterior glenoid fossa with transosseous sutures to re-establish normal shoulder anatomy and function (Randelli 2012). In some cases when a large and engaging Hill-Sachs lesion is present, the remplissage technique may be added, i.e. a transfer of the infraspinatus tendon and the posterior capsule is done to fill the Hill-Sachs defect (Zhu 2011).
The goal of non-anatomic repairs, such as the Bristow-Laterjet procedure and the less commonly performed Magnusson-Stack and Putti-Platt procedures (Ahmad 2005), is to restore stability to the glenohumeral joint by compensating for capsulolabral and osseous injuries with an osseous or soft tissue block to passively limit glenohumeral translation (Van Tongel 2011). The Bristow-Latarjet procedure is performed mainly in people who have bone loss from the front of the glenoid. This procedure involves an osteotomy of the coracoid process with pectoral tendon conservation. The coracoid tip is transferred with the conjoint tendon and is attached with one or two screws to the anterior glenoid (Matthes 2007). The goal of this surgery is to compensate for bone loss, and the transferred muscle acts as an additional muscular strut to prevent further dislocations (Omidi-Kashani 2008). The Magnusson-Stack procedure aims to tighten the subscapularis by altering its insertion site from the lesser tuberosity to a groove created lateral to the bicipital groove. The Putti-Platt procedure involves shortening the subscapularis tendon.
Each of these methods of surgery has undergone several modifications since its first appearance in orthopaedic practice; changes involve not only the surgical approach (arthroscopic or open) but also anchor or suture types and their placement. Following any of these surgical interventions, immobilisation and a rehabilitation exercise regimen are generally warranted to allow proper healing of repaired structures and to regain normal range of motion and normal dynamic control of the glenohumeral joint (Hayes 2002).
How the intervention might work
Common surgical procedures for post-traumatic anterior shoulder instability in adults are aimed at restoring the integrity of damaged structures and ultimately enabling return to normal activities without functional disability (Brophy 2009). Several risk factors for recurrent instability after surgical repair have, however, been identified: bony Bankart lesions, engaging Hill–Sachs lesions, poor glenohumeral ligament mechanical properties, specific glenoid anatomy described as an inverted pear, participation in contact sports and younger age. It is important to note that these factors may also influence the type of surgery that will be performed (Van Tongel 2011).
Nowadays, surgeons generally use surgical interventions that aim to restore normal anatomy; such as the Bankart procedure, which involves repair of the Bankart lesion. The reported complications of such anatomic procedures are generally low. Open anatomical repairs can provide good results, but arthroscopically performed anatomical repairs, now often used, seem to be of equal efficacy while being better tolerated by patients and decreasing morbidity (Van Tongel 2011). Non-anatomic methods, such as the Putti-Platt procedure, where tendon or muscles are shortened/transferred in an attempt to stabilise and strengthen the shoulder joint, are often preferred by surgeons when more extensive damage to the soft tissues and bony structures of the shoulder is present. While these methods are considered effective in reducing the recurrence of instability, complications are more frequent, including loss of range of motion and arthropathy (Murray 2013). Non-anatomic repairs are performed most often with an open approach. Arthroscopically performed non-anatomic repair is also an option but is more technically challenging (Van Tongel 2011).
Why it is important to do this review
Overall, it is uncertain what is the best surgical procedure for treating traumatic anterior shoulder instability (Grumet 2010). This uncertainty includes also the type of surgical approach (e.g. arthroscopic or open surgery) and the type of sutures or anchors used to stabilise and repair shoulder structures (Brophy 2009). The previous Cochrane review (Pulavarti 2009), which focused on a similar topic to this review, included three trials comparing arthroscopic versus open surgery. This review found "insufficient evidence" to inform practice for this comparison. Our review will update the search for evidence and will expand the scope to include all comparisons of surgical interventions, including different types of fixation materials and techniques, used for treating adults with post-traumatic anterior shoulder instability.