Irreparable massive rotator cuff tears Managed with Lower Trapezius tendon transfer

Topic / Overview

Biomechanical rationale, patient selection, surgical technique, and clinical outcomes for Lower Trapezius Tendon Transfer (LTTT) in the management of irreparable posterosuperior rotator cuff tears and brachial plexus palsy, based strictly on the provided lecture transcript.

Background / Problems

• Dynamic Shoulder Biomechanics: The deltoid alone is insufficient for active shoulder elevation if dynamic rotator cuff function is absent.

  • Rotator Cuff Preservation with Zero Deltoid: Patients with complete deltoid loss (“zero deltoid”) can maintain full active flexion and normal functional testing (such as Jobe’s test) when the rotator cuff force couple remains intact.

  • Deltoid Preservation with Rotator Cuff Paralysis: A cited Japanese study demonstrated that selectively anesthetizing the suprascapular nerve (paralyzing the supraspinatus and infraspinatus) in the presence of a normal deltoid and an intact superior capsule induced pseudoparalysis (weak flexion) in 80% of subjects.

• Limitations of Static Reconstruction: While arthroscopic Superior Capsular Reconstruction (SCR) relieves pain and functions via static restraint, it does not restore dynamic muscle pull. The speaker emphasizes restoring dynamic muscle function whenever feasible.

• Limitations of Latissimus Dorsi Transfer: Although historically used for posterosuperior cuff tears, the latissimus dorsi acts primarily as an internal rotator, possesses a less favorable line of pull, and requires difficult neuromuscular retraining.

• Functional Deficit of External Rotation Loss: Loss of infraspinatus and teres minor function severely impairs activities of daily living requiring active external rotation (e.g., opening a door, reaching behind the back).

• Age vs. Activity Level: Chronological age alone is not a strict cutoff; functional demand dictates surgical candidacy (e.g., active 70-year-old farmers lifting heavy loads versus sedentary 50-year-old office workers).

Classification or Concept

1. Biomechanical Line of Pull (Force Vector)

• Anatomical Alignment: The lower trapezius muscle shares an almost identical line of pull (force vector) with the native infraspinatus and posterosuperior rotator cuff across the posterior scapula.

• Kinematic Advantage: Biomechanical studies (including the speaker’s own research) demonstrate that LTTT provides a superior moment arm and improved joint kinematics compared to latissimus dorsi tendon transfer.

• Synergistic Activation: Electromyography (EMG) and clinical testing confirm that the lower trapezius activates naturally and synergistically during shoulder external rotation and flexion, eliminating the complex retraining required for latissimus dorsi transfers.

2. Imaging and Cuff Tear Classification Parameters

• Tendon Remnant Threshold: Referring to a study by Meyer, the speaker notes that a short remaining tendon stump measuring less than 0.5 cm to 1 cm is associated with worse outcomes than severe fatty atrophy alone.

• Radiographic & Muscular Grading: Case demonstrations highlight successful outcomes in patients with Goutallier Grade 4 fatty infiltration and Hamada Grade 3, 4, and 5 cuff tear arthropathy.

Indications / Patient Selection

• Primary Indications:

  • Irreparable posterosuperior rotator cuff tears (supraspinatus and infraspinatus tears), particularly with loss or weakness of the teres minor (Hornblower’s sign / external rotation lag).

  • Brachial plexus palsy (adult and pediatric cohorts) requiring restoration of external rotation and overhead elevation.

  • Active older patients (e.g., a 71-year-old ski instructor) who wish to avoid or are apprehensive about reverse shoulder arthroplasty.

• Symptomatic Presentation:

  • True painless pseudoparalysis (e.g., active elevation restricted to 40–45 degrees).

  • Severe weakness in external rotation (noted to cause serious symptoms in roughly 20% of patients with combined infraspinatus and teres minor atrophy).

• Prerequisite: Intact axillary nerve function (when evaluating for concomitant nerve pathology) and functional lower trapezius muscle bulk.

Technique / Principles: Arthroscopically Assisted LTTT

Originally pioneered as an open procedure for brachial plexus injuries, the speaker transitioned to an arthroscopically assisted technique utilizing an Achilles tendon allograft.

1. Lower Trapezius Harvest

• Landmark Identification: Identify the lower trapezius insertion along the medial border and inferior angle of the scapular spine.

• Dissection: Meticulously clear overlying subcutaneous fat to expose the lower trapezius muscle belly and fascia, freeing it from adjacent medial tissues to mobilize the tendon excursion.

2. Allograft Preparation

• Graft Choice: Achilles tendon allograft (noted to repopulate with living host fibroblasts and revascularize over time).

• Preparation: An assistant prepares and colors the graft on the back table, placing traction/reinforcement sutures along the graft.

3. Arthroscopic Passage and Fixation

• Anterior Footprint Fixation: The Achilles allograft is shuttled arthroscopically into the subacromial space and anchored anteriorly onto the supraspinatus footprint of the greater tuberosity using two suture anchors (even without attempting repair of the native torn rotator cuff).

• Posterior Graft-to-Muscle Attachment: Tension the allograft and suture it securely into the harvested lower trapezius muscle/tendon unit.

• Concomitant Procedures: Perform biceps tenodesis if indicated.

Results / Evidence Cited by the Speaker

• Clinical Series (In Publication): A series of 42 patients treated with arthroscopically assisted LTTT demonstrated high patient satisfaction and functional recovery, including:

  • Reversal of true pseudoparalysis in massive rotator cuff tears.

  • Resolution of proximal humeral head migration.

  • Marked reduction in scapular winging.

• Biologic Graft Incorporation: Second-look arthroscopy following revision surgery demonstrated that the Achilles allograft completely covered the superior cuff defect, underwent robust revascularization, and contained living fibroblasts, closely resembling a native rotator cuff tendon.

• Revision Compatibility: In a patient who required conversion to a reverse shoulder arthroplasty 2 years after LTTT, the intact, vascularized lower trapezius transfer remained in place and contributed to excellent postoperative external rotation and function.

Complications / Limitations

• Scapular Dyskinesia / Winging: Detachment or improper tensioning of the trapezius requires careful management, though the speaker notes scapular winging improved substantially in the clinical cohort.

• Need for Allograft: Because the native lower trapezius tendon does not reach the greater tuberosity directly, an interpositional graft (Achilles tendon allograft) is mandatory.

Practical Clinical Implications

• Evaluate Activity Over Age: Base surgical candidacy for tendon transfers on functional demand rather than chronological age alone.

• Assess the Teres Minor: Always examine external rotation strength and teres minor integrity in massive posterosuperior cuff tears; loss of both infraspinatus and teres minor creates profound functional disability that static procedures (like SCR) fail to dynamically restore.

• Preserve Future Salvage Options: Performing an arthroscopically assisted LTTT does not burn bridges; if the patient eventually progresses to reverse shoulder arthroplasty, the healed transfer acts as a functional posterior cuff to preserve active external rotation.

Key Take-Home Points

• Force Couple Imperative: Dynamic rotator cuff balance is critical for shoulder elevation; experimental paralysis of the supraspinatus and infraspinatus causes pseudoparalysis in 80% of individuals despite a normal deltoid and intact capsule.

• Why Lower Trapezius Over Latissimus Dorsi: The lower trapezius replicates the native infraspinatus force vector, offers a superior moment arm, and fires naturally during external rotation and elevation without requiring complex muscle retraining.

• Surgical Construct: Arthroscopically assisted transfer using an Achilles tendon allograft fixed anteriorly to the greater tuberosity with two anchors and sutured posteriorly to the mobilized lower trapezius.

• Clinical Outcomes: Proven effective in a series of 42 patients (including Goutallier 4 and Hamada 3–5 cases) for reversing pseudoparalysis, restoring external rotation, correcting proximal humeral migration, and reducing scapular winging.