Biomechanical analysis of latissimus dorsi, pectoralis major, and pectoralis minor transfers in subscapularis-deficient shoulders

Moment arms of the coracobrachialis and short head of biceps following a Latarjet procedure: a modeling study

BACKGROUND

The Latarjet procedure transfers the coracoid process to the anterior glenoid. This prevents recurrent anterior humeral dislocation but alters the origins of the coracobrachialis (CBR) and short head of the biceps (SHB). The impact of this alteration on the moment arms of these muscles has not been examined.

METHODS

The Newcastle Shoulder Model was updated with 15 healthy cadaveric bone models to create customized shoulder models. The CBR and SHB muscles were attached to the anterior glenoid via an elliptical wrapping object. Muscle moment arms were calculated for abduction, forward flexion, scapular plane elevation, and internal rotation with 20° and 90° of abduction. Statistical comparison of moment arms between native and Latarjet shoulders was performed using spm1D.

RESULTS

By transferring the origins of the CBR and SHB to the anterior glenoid, both muscles had extension moment arms during glenohumeral elevation in the coronal, sagittal, and scapular planes. Their average moment arms during abduction (-30.4 ± 3.2 mm for CBR and -29.8 ± 3.0 mm for SHB) and forward flexion (-26.0 ± 3.1 mm for CBR and -26.2 ± 3.2 mm for SHB) suggested that their role after the Latarjet procedure changed compared with their role in the native shoulder (P < .001). At higher abduction levels, both the muscles had higher internal rotation moment arms compared with the native shoulder.

CONCLUSION

The Latarjet procedure affected the moment arms of the CBR and SHB. Both muscles had increased extension and internal rotation moment arms at higher degrees of elevation compared with the native shoulders. This finding suggests that these muscles act as dynamic stabilizers after the Latarjet procedure.

Irreparable Subscapularis Tears: Current Tendon Transfer Options

PURPOSE OF REVIEW

Irreparable subscapularis tears, especially in younger patients with higher functional demands, present a challenging entity. Pectoralis major and latissimus dorsi tendon transfers are commonly considered for surgical management of this pathology, yet no consensus exists regarding the superior option. The purpose of this article is to review the most current tendon transfer techniques for irreparable subscapularis tears.

RECENT FINDINGS

For decades, transfer of the pectoralis major has been considered the gold standard technique for irreparable subscapularis tears. This transfer was found to reduce pain and improve functional outcome scores, yet range of motion and force of internal rotation were not maintained in long-term follow-up studies. The latissimus dorsi tendon transfer for the same indications has demonstrated biomechanical superiority in recent cadaveric studies with promising short-term results clinically. Both pectoralis major and latissimus dorsi tendon transfers improve outcomes of patients with irreparable subscapularis tears. Future comparative studies are still needed to determine superiority amongst techniques.

Anterior capsular reconstruction in irreparable subscapularis tear: human dermal allograft

BACKGROUND

The irreparable subscapularis (SSc) tears pose an extremely difficult situation to manage, especially in the younger population. The anterior capsular reconstruction (ACR) with human dermal allograft (HDA) is an alternative to tendon transfer with sound biomechanical advantages and clinical outcomes. The purpose of this study was to evaluate the early clinical and radiologic outcomes of open ACR with HDA in patients with irreparable SSc tears.

METHODS

Eighteen patients who had an open ACR with HDA for irreparable SSc tears between August 2020 and January 2022 were enrolled. There were 11 male and 7 female patients with a mean age of 63.7 years and a mean follow-up of 17 months (range, 12-28 months). The dominant side was affected in 10 patients. One of the 18 patients had reconstruction with single-layer HDA, 14 had double-layer HDA, and 3 had SSc augmentation over double-layer HDA. Clinical and radiologic outcomes were assessed and compared pre- and postoperatively.

RESULTS

There was significant improvement in visual analog scale score from 6.6 ± 1.6 to 1.6 ± 1.5 (P < .001) and in the total University of California-Los Angeles shoulder score from 12.4 ± 4.3 to 29.0 ± 4.5 (P < .001). Forward flexion, abduction, and internal rotation (IR) increased by 28.6°, 32.5°, and 11.8°, respectively (P < .001). External rotation decreased by 6.4° (P = .020). There was notable improvement in IR strength (percentage of that of the opposite, normal side) from 66.0% ± 19.4% to 84.4% ± 22.3% (P = .008). The mean postoperative coracohumeral distance improved from 3.0 to 6.0 mm (P < .001), the anterior translation of the humeral head reduced from 1.5 to 0.5 mm (P = .210), and the acromiohumeral interval from 8.1 to 8.8 mm (P = .070). The patients' satisfaction at final follow-up was rated 4.1 of 5.0 (P < .001). Sixteen of 18 patients (88.9%) had the HDA healed at the glenoid and humeral side, and 2 (11.1%) had retear at the final follow-up. Among the 17 who had double-layer HDA, none showed any healing between the layers.

CONCLUSION

This study showed that early significant and comprehensive improvement inclusive of pain relief, improvement in range of motion, IR strength, and reduction of anterosuperior translation was achievable by open ACR with HDA for irreparable SSc tear.

Fully Arthroscopic Pectoralis Minor Tendon Transfer with Bone Fragment for Irreparable Subscapularis Tears

Several techniques to treat irreparable subscapularis (SSC) tendon tear have been described. We introduce a fully arthroscopic technique for pectoralis minor tendon with bone fragment transfer. This procedure starts with glenohumeral exploration and evaluation of the remaining SSC mobility. Then we detach and release the pectoralis minor (PMi) tendon with bone fragment from the coracoid, protecting the plexus structures. Next, the PMi tendon with bone fragment is fixed on the lesser tuberosity passing under the coracoid. This procedure is technically demanding and could be performed safely with low invasiveness and high reproducibility by understanding the regional anatomy and the well-described technique.