2015 ISAKOS Biennial Congress ePoster #2120

Anatomical Study of the Feasibility of the Pectoralis Minor Transfer for Irreparable Subscapular Tear

Apostolos Gantsos , MD, Paris FRANCE
Felipe A. Reinares, MD, Santiago CHILE
Constantina Moraiti, MD, PhD, Paris FRANCE
Constantina Moraiti, MD, PhD, Paris FRANCE

Institut de la Main, Paris, FRANCE

FDA Status Not Applicable

Summary: When performing a pectoralis minor transfer for subscapularis deficiency it is essential to identify the musculocutaneous and axillary nerves and branches. In some cases, a subcoracobicipital transfer may not be feasible and a more superficial transfer should be considered.

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Abstract:

Introduction

The prevalence of anterosuperior rotator cuff or isolated subscapularis tears is lower than that of posterosuperior tears. So, if the subscapularis is retracted with fatty infiltration more than 3 , a tendon transfer is indicated .Pectoralis major transfer has been mainly reported and medium trapezium transfer more rarely. The goal of this anatomical study was to analyse the feasibility of transfer the pectoralis minor in its entirety and evaluate the relationship between the transferred muscle and musculocutaneous and axillary nerves. The hypothesis of this study is that pectorallis minor (Pm) transfer for subscapularis tendon deficiency can be easily and safely performed under the conjoined tendon without affecting the axillary or the musculocutaneous nerve.

Methods

16 fresh cadavers were dissected; 9 male (mean ± SD age, yrs) and 7 female (mean ± SD age, yrs). The following measures were implemented after Pm transfer : The distance between the medial coracoid (insertion of the Pectoralis minor) and the insertion of the subscapularis on the lesser tuberosity in external rotation , neutral rotation and internal rotation; The distances between coracoid process and Pm, Pm and musculocutaneous nerve, Pm and axillary nerve. The measurements were accomplished using a precision caliper and performed by two different observers, independenly and blindly. The reason for this is to consider for interobservator correlation.

Results

The median distance between the coracoid process and pectoralis minor muscle was 24 ± 7.7 mm, the width of the coracoid was 24 ± 5.2 mm.
According to neural structures, Pm-MCN distance was 23.25 ± 21.9 mm, and the CP-MCN distance was 72.1 ± 32.4 mm. Respect to the axillary nerve, the Pm- axillary nerve distance was 4.9 ± 0.7mm.
In evaluating the distance between the coracoid process and the lesser tuberosity in different rotations, these were: 29.2 ± 5.5 in internal rotations, 41.1 ± 8.9 mm in neutral rotations and 51.1 ± 10.7mm in external rotations. When performing comparative analysis with Mann-Whitney tests, this distance increases significantly between internal rotation and neutral or external rotation (p <0.05), however, there is no significant difference between neutral and external rotation. (p> 0.05).

Discussion

A pectoralis minor transfer is a rarely performed procedure that has been proposed as a good alternative for subscapularis insufficiency. The distance between the coracoid process and the lesser tuberosity increases significantly between internal rotation and neutral or external rotation, however, there is no significant difference between neutral and external rotation. The distance between the pectorallis minor and the musculocutaneous nerve branches observed in this study presents significant variability. Many variations in the musculocutaneous nerve at the conjoined tendon were observed.

Conclusion

When performing a pectoralis minor transfer, it is essential to identify the musculocutaneous and axillary nerves and branches. In some cases, a subcoracobicipital transfer may not be feasible and a more superficial transfer should be considered.