Role of Trapezius Transfer for Shoulder Reconstruction in Adult Traumatic Brachial Plexus Injuries: Literature Review

Abstract

IntroductionShoulder instability and lack of shoulder mobility are common and exhausting problems in adult patients with traumatic brachial plexus injuries. Even with functioning elbow, wrist, and fingers, upper limb function is significantly hampered by deficient shoulder function. Primary nerve reconstruction remains the "gold standard" in brachial plexus management. If surgery is early and successful, adequate reinnervation of the deltoid, teres minor, supraspinatus and infraspinatus muscles can be achieved, as well as glenohumeral joint stability [1,2].However, secondary shoulder reconstruction is needed in clinical scenarios, such as neglected cases (>1 year without any attempt for reconstruction) and cases of complete or partial failure of recovery of both the deltoid and rotator cuff after primary reconstruction.Many options are available for secondary shoulder reconstruction. Trapezius transfer is one of those important options, and our goal is to review the indications, techniques, and outcomes of trapezius transfer and compare it with the alternative options. First, we should revisit the basic concepts of shoulder kinematics and tendon transfer. Kinematics of the ShoulderThe shoulder range of motion is achieved by the scapulohumeral rhythm, which is the coordinated motion of the glenohumeral, scapulothoracic, acromioclavicular and sternoclavicular joints. For shoulder abduction, an approximately 2:1 ratio of glenohumeral to scapulothoracic motion is required [3][4][5].The rotator cuff muscles are primarily dynamic stabilizers for the shoulder during abduction, forward flexion, and extension that act by resisting the relative upward shearing moment at the glenohumeral joint by the deltoid in early abduction and through a force couple of the subscapularis anteriorly and the infraspinatus posteriorly [6].The importance of the force couple function generated by the glenohumeral stabilizers is indicated by the pseudoparalysis of the shoulder in massive rotator cuff tear. This pseudoparalysis extends below the humeral head equator despite normal brachial plexus and deltoid function; however, due to the force couple loss, the humeral head cannot be contained. An important study done by Gerber et al. demonstrated 45% loss of abduction strength and 70% loss of external rotation strength after nerve blocks of the infraspinatus. Paralysis of both the supraspinatus and infraspinatus led to a decrease in abduction strength of 75% and a decrease in external rotation strength of 80%. The teres minor plays a role in external rotation strength at any angle of shoulder abduction less than 20% [7].These relations explain why isolated trapezius transfer alone leads to an obligatory proximal migration of the humeral head, narrowing the space between the humeral head and acromion, which causes mechanical impingement and decreases the trapezius lever arm, leading to ineffective shoulder abduction and flexion [8].The deltoid and rotator cuff muscles have relatively low excursion but generate high tension. The upper trapezius ...

Systematic Review With Meta-Analysis: Are Muscle Transfers a Satisfactory Treatment Option to Restore Shoulder Abduction in Delayed Adult Brachial Plexus Injuries?

“…Trapezius muscle hypertrophy due to the overuse following deltoid muscle paralysis is another cause favoring its use for transfer [46][47]. However, the spinal accessory nerve is commonly used as a donor nerve for nerve reconstruction procedures, resulting in paralyzed middle and lower trapezius but sparing the upper trapezius [30,48]. Therefore, the lower trapezius muscle is less available for transfer compared to the upper trapezius muscle.…”

“…Saha (1967), consequently, modified this technique by mobilizing the upper and middle segments of the trapezius muscle from its origin and thus transfer was made 5 cm longer. Therefore, Saha's technique allowed the longer lever arm by fixing the acromion to the humerus just below the greater tuberosity with two 6.5 mm cancellous screws with the arm in 80 to 90 degrees of abduction [48,50]. Saha's technique was adopted by Ruhmann et al (2005) and Bertelli 2011 [31][32][33].…”

“…Lower trapezius transfers have been used to primarily improve shoulder external rotation [30,48]. However, dual upper and lower trapezius transfer has been found to improve shoulder abduction biomechanics as well as shoulder external rotation [30,48 ].…”

“…Lower trapezius transfers have been used to primarily improve shoulder external rotation [30,48]. However, dual upper and lower trapezius transfer has been found to improve shoulder abduction biomechanics as well as shoulder external rotation [30,48 ]. It has been argued that upper trapezius transfers only provide a tenodesis effect on the glenohumeral joint and the recovered abduction was mainly achieved by the active action of periscapular muscles, pectoralis major, biceps, and triceps muscles [50].…”

“…It has been argued that upper trapezius transfers only provide a tenodesis effect on the glenohumeral joint and the recovered abduction was mainly achieved by the active action of periscapular muscles, pectoralis major, biceps, and triceps muscles [50]. This could be explained by the upward humeral head migration effect following isolated upper trapezius transfer especially in the presence of rotator cuff dysfunction [48]. Elhassan reported an average gain in shoulder abduction of 40 degrees post dual upper and lower trapezius transfers with increased shoulder stability and improved average DASH score from 59 preoperatively to 47 postoperatively [30].…”