37 Pectoralis Major Transfer for Irreparable Subscapularis Tears

10.1055/b-0039-167686

37 Pectoralis Major Transfer for Irreparable Subscapularis Tears

Laurence D. Higgins and William E. Daner III

Abstract

Pectoralis major transfer for irreparable subscapularis tears is an option to stabilize and restore internal rotation in patients with this challenging problem. This chapter describes the ideal candidate and summarizes important steps of the procedure that are required to have a successful outcome.

37.1 Key Principles

Untreated subscapularis tears or failed repairs can lead to chronic shoulder pain, instability, diminished range of motion, and loss of internal rotation strength. In some patients, the extent of the tear, degree of retraction, or poor tendon quality may preclude an adequate direct repair. In an elderly, well-compensated patient with pain, nonoperative care or limited surgical debridement may be an acceptable alternative to repair. ¹ ^, ² For patients in whom surgical repair/reconstruction is desired, options are limited and depend greatly upon the static stability of the glenohumeral joint. The best option in most cases to restore function in a subscapularis-deficient shoulder in terms of adequate excursion and mechanism of action is a muscle–tendon transfer, the most common of which is the pectoralis major tendon transfer. In the appropriately selected patient, studies have shown pectoralis major transfer to be effective in improving shoulder function, strength, and pain relief. ³ ^– ⁹

37.2 Expectations

Following pectoralis major transfer for an irreparable subscapularis tear, patients should expect restoration of shoulder stability and pain relief (though it may not be complete). Most patients will be able to resume activities of daily living and activities that require the affected arm abducted or overhead. Full restoration of internal rotation is not likely and a normal lift-off test should not be anticipated. Restoration of full premorbid strength is not achievable.

37.3 Indications

Split pectoralis major transfer is indicated for patients with an irreparable rotator cuff tear involving the subscapularis.
Fatty infiltration of subscapularis muscle belly, poor tendon quality, and/or significant tendon retraction.
Failed prior subscapularis repair.
The patient may have associated anterior shoulder instability.

37.4 Contraindications

37.4.1 Relative

Advanced age.
Medical comorbidities.
Cognitive: Patient must be able to comply with postoperative motion and weight-bearing restrictions and must be able to participate with physical therapy thereafter.
Stiffness.
Nerve injury.
Posterosuperior rotator cuff deficiency.

37.4.2 Absolute

Significant glenohumeral joint arthritis.
Static subluxation of the affected glenohumeral joint.

37.5 Special Considerations

Pre-op imaging:
- X-rays may demonstrate a decreased acromiohumeral interval, which may indicate a large tear.
- MRI is used not only to identify the rotator cuff tear but also to assess tendon quality and degree of atrophy/fatty infiltration.

37.6 Special Instructions, Position, and Anesthesia

The patient is placed in the beach-chair position with the back of the bed elevated approximately 20 degrees. The operative arm is placed in a SPIDER pneumatic limb positioner (Smith & Nephew, Andover, MA). This procedure is usually done under general anesthesia, usually with a supplemental interscalene block for postoperative pain relief.

37.7 Key Procedural Steps

37.7.1 General Technique of Split Pectoralis Transfer (Authors’ Preferred Technique)

A standard deltopectoral approach is made. An incision is made approximately 10 to 15 cm in length extending from just superior to the medial side of the coracoid toward the anterior deltoid’s insertion on the proximal humerus.
The interval is identified by locating the triangular region of the adipose tissue of the Mohrenheim fossa proximally. The interval is developed proximally and the crossing “French vessels” are identified and coagulated ( Fig. 37.1 ).
A sharp Hohmann retractor is placed over the coracoid process. Dissection is then carried distally and can largely be done bluntly as the deltoid is separated from the pectoralis (this may not be the case in revision procedures).
Care is taken to preserve the cephalic vein, which is taken laterally with the deltoid.
Subdeltoid adhesions are released and a Brown retractor is placed to retract the deltoid muscle belly laterally.
Beneath the clavipectoral fascia, the conjoint group is readily visualized and the large subscapularis tear will be identified. Preservation of the frequently intact inferior subscapularis is critical.
Care must also be taken to identify the long head of the biceps tendon, which may have subluxed from the intertubercular groove. This may be released and tagged for later tenodesis.
The pectoralis major is then identified and any adhesions around its posterior margin are released. The sternal head of the pectoralis major is isolated by exploiting the natural raphe between the clavicular and sternal heads and bluntly extending it from medial to lateral ( Fig. 37.2 ). It is important to avoid dissecting this interval more than 8 cm from the lateral border of the muscle, as this could disrupt the lateral pectoral nerve. The arm is then positioned in forward flexion and internal rotation.
A plane is then carefully developed between the conjoint group and the pectoralis minor as well as beneath the conjoint muscle/tendon group itself. Care is taken to ensure that the brachial plexus, which sits posteromedially, is protected. This step is completed prior to harvesting to ensure the volume of muscle harvested will pass through this interval.
Laterally, the fibers of the sternal head are released from their insertion, which lies posterior to the fibers of the clavicular head with the knowledge of the size of the aperture in the retrocoracoid space ( Fig. 37.3 ). The released sternal head is then tubularized with no. 2 FiberWire sutures passed in a running Kessler fashion ( Fig. 37.4 ).
The transferred sternal head is then passed posterior to the clavicular head and through the space developed under the conjoint group ( Fig. 37.5 ).
Four no. 5 FiberWire sutures are passed through the sternal head tendon in a Mason–Allen fashion.
The lesser tuberosity is then prepared by removing soft tissue and decorticating the bone at the planned insertion site of the muscle/tendon transfer.
The sutures of the sternal head are then passed transosseously through the lesser tuberosity ( Fig. 37.6 ). Note that the location at which the sutures are passed is carefully chosen to ensure that the transferred sternal head is appropriately tensioned. After transosseous passage of the sutures, they are passed through and tied over a button to prevent the sutures from pulling through the bone. Typically, the sutures are tied from inferior to superior to ensure optimal tensioning ( Fig. 37.7 ).
The arm is then put through a range of motion, paying attention to the degree of external rotation at which the transferred tendon begins to tension.
The surgical site is copiously irrigated and closed in layered fashion.