33 Arthroscopically Assisted Lower Trapezius Transfer for Irreparable Posterosuperior Rotator Cuff Tears

Joaquin Sanchez-Sotelo and Bassem T. Elhassan

Summary

Posterosuperior rotator cuff tears may lead to substantial pain and weakness. Primary repair of posterosuperior cuff tears may not be feasible or reliable for very large, chronic tears with substantial atrophy, fatty infiltration, and poor tendon quality. Tendon transfers represent salvage procedures that may be considered in these circumstances. Direct transfer of the lower portion of the trapezius to the infraspinatus tendon was described as a successful surgical procedure to improve strength in external rotation for the paralytic shoulder. This procedure has been adapted to be performed as an indirect arthroscopically, assisted tendon transfer for irreparable posterosuperior cuff tears. The lower portion of the trapezius is harvested through a relatively small posteri- or exposure. A graft (typically an Achilles tendon allograft) is then delivered into the subacromial space from this posterior surgical site; the narrower end of the Achilles allograft is then fixed to the anterior portion of the greater tuberosity using arthroscopic anchors and techniques. The arm is placed in abduction and external rotation and the wider portion of the graft repaired to the lower trapezius (LT) with multiple nonabsorbable and absorbable sutures. The shoulder is immobilized in external rotation for 6 weeks. A few cadaveric studies have analyzed the biomechanical properties of transferring the LT. Early clinical results are promising, with improvement in pain, motion, and strength. Follow-up studies will be required to determine the long-term outcome of this reconstructive technique.

Keywords: allograft, fatty infiltration, rotator cuff tear, tendon transfer, trapezius

33.1 Introduction

Symptomatic posterosuperior rotator cuff tears that not amenable to surgical repair represent a substantial challenge. Multiple procedures have been considered for the salvage of these shoulders, including debridement, tendon transfers, reconstruction of the superior capsule, and reverse shoulder arthroplasty. Transferring the lower portion of the trapezius to the greater tuberosity has become our tendon transfer of choice for patients with massive irreparable posterosuperior cuff tears for no or minimal cartilage damage (? Fig. 33.1).

Transfer of the trapezius was initially described to improve external rotation and elevation motion and strength in paralytic shoulders.1,2,3,4,5 A few cadaveric studies have analyzed the biomechanical properties of the LT transfer.6,7 The outcome of open indirect transfer of the lower portion of the trapezius to the greater tuberosity using a intercalary Achilles tendon allograft has been reported to be satisfactory.8 This initial open technique has been modified to be performed with arthroscopic assistance,9 as detailed in this chapter.

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Fig. 33.1 Schematic representation of the final construct after indirect transfer of the lower trapezius to the greater tuberosity.

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Fig. 33.2 Our preference is to perform this procedure with the patient in the beachchair position. The arm is placed in an articulated mechanical limb positioner. It is critical to confirm adequate draping of the surgical field to allow access several centimeters medial to the medial border of the scapula.

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Fig. 33.3 Main portals used: posterolateral subacromial viewing portal (1), 50-yard-line subacromial portal (2), anterior subacromial portal to retrieve allograft leading end sutures (3), and anterosuperior subacromial portal for graft fixation (4).

33.2 Patient Positioning (? Fig. 33.2)

? High beachchair position (barber chair position)

? Articulated mechanical limb positioner

? Confirm unrestricted access to whole scapula

? Drape the arm free attached to the mechanical limb positioner

? Drape the surgical field to at least 5 cm medial to the medial border of the scapula

33.3 Portal Placement (? Fig. 33.3)

? Posterolateral subacromial portal as main viewing portal

? Two lateral subacromial portals

? Centered in reference to the humeral head

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Fig. 33.4 An Achilles tendon allograft is prepared in the back-table to receive two heavy nonabsorbable sutures. Partially coloring the allograft will aid with orientation at the time of arthroscopic fixation.

? Working portal

? Viewing portal

? Anterior for retrieval of allograft leading end sutures

? One anterosuperior subacromial portal for graft fixation

33.4 Surgical Technique

33.4.1 Partial Cuff Repair and Biceps Tenotomy/Tenodesis if Indicated

? Bursectomy, selective acromioplasty

? Biceps assessment, tenotomy/tenodesis if indicated

? Cuff tear pattern identification and release/mobilization if indicated

? Partial cuff repair

? Keep sutures after tying for augmentation of allograft fixation

33.4.2 Achilles Tendon Allograft Preparation (? Fig. 33.4)

? Narrow (calcaneal) end of the graft prepared for fixation to the tuberosity

? Place two heavy nonabsorbable sutures (Fiberwire #2 by Arthrex, Naples, FL; Orthocord by DePuy, Warsaw, IN; or equivalent) at the end of the graft using running locked sutures, one on each side of the graft

? Sutures of different color will make suture identification easier at the time of arthroscopic fixation

? A marking pen may be used to partially color one of the sides of the graft to aid with orientation of the graft at the time of arthroscopic fixation

? Depending on the fixation mode preferred to secure the graft to the transferred LT, nonabsorbable sutures may also be placed on the opposite (wider) side of the graft for later use

33.5 Lower Trapezius Tendon Harvesting and Mobilization

? Place a horizontal skin incision parallel to the spine of the scapula and slightly below the level of the spine, starting at the medial border of the body of the scapula and measuring approximately 8 cm (? Fig. 33.5a).