Introduction
Muscle weakness is a frequent sequela after obstetric brachial plexus palsy (obpp)
and might be improved by muscle transpositions, especially at the shoulder level [[1]]. The teres major muscle (tmm) is included in the technique described by Hoffer
[[2]] to enhance active lateral rotation of the shoulder, where this muscle should address
the function of the infraspinatus muscle.
We propose a single transfer of the tmm in selected conditions in children suffering
obpp sequelae:
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1. when shoulder flexion and/or abduction are weak against gravity (active ROM less
than 90° with a strength less or equal M3)
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2. when the tmm shows cocontractions during shoulder abduction (mixed reinnervation
of the dorsal cord)
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3. to add muscle volume to a cranial trapezius transfer for weak shoulder abduction
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4. to modify a Hoffer transfer [[2]], using the latissimus dorsi muscle (ldm) to improve the lateral shoulder rotation
with an abducted arm, and tmm to allow an active abduction up to 90° (horizontal line),
which will bring the transferred ldm under good tension.
Essentially, the tmm might be considered as a valuable functional muscle transfer
to enhance shoulder abduction and elevation in selected children with obpp sequelae,
under 10 years of age with reasonable body weight. The muscle thereby improves prime
movers of the shoulder joint.
Surgical Technique ([figure 1])
Figure 1
Scheme explaining the harvest and transposition of the teres major muscle. A: detachment of all distal insertions of the tmm onto the lower scapular angle.
B: pivot point at the level of the neurovascular bundle. C: tunnel under and medial
to the proximal humerus, beside the maintained conjoint tendon insertion. D: new fixation
onto the clavicle or deltoid muscle attachment.
The child is placed in a lateral position under general anesthesia. A double access
is needed to the midaxillar line (to detach the muscle) and to the acromio-clavicular
region (to transpose the muscle onto the antero-lateral deltoid muscle (dm) insertion).
A strait skin incision is drawn beginning in the axilla following down the midaxillar
line until the lower angle of the scapula. The subcutaneous tissue is divided, and
the lateral borders of both ldm and tmm are identified and dissected free. The tmm
is dissected free from the ldm progressively from its lateral border, from proximal
maintaining its tendon insertion onto the humerus down to the lower scapular angle,
where it is completely detached. The medial border is freed from distal to proximal;
and particular attention is paid to preserve the neurovascular bundle, which lies
at the deeper proximal lateral border, a few cm above the well visible bundle to the
ldm ([figure 2]).
Figure 2
Harvest of the tmm detached from the inferior scapular angle.
The dissection continues until the tmm is freed all around and maintains only its
proximal tendon and the neurovascular bundle. At this stage, the free muscular rim
may be reinforced by several absorbable mattress sutures, or a running suture, with
a long suture end which will be grasped to further mobilize the muscle.
A second incision is conducted from the proximal delto-pectoral groove about 5 cm
more proximally; the subcutaneous fat is divided and the cephalic vein is respected;
the often hypotrophic anterior and middle parts of the dm are identified and their
insertion on the lateral clavicle dissected free. From this approach, using the upper
delto-pectoral access, a tunnel is prepared, going under the dm, more laterally and
distally, crossing above the humerus. From the other incision, in line with the respected
conjoined tendon, the tunnel is completed moving over the humerus, to join the dissecting
finger(s) from above.
The tunnel is widened for 2 fingers by gentle blunt dissection and after myorelaxation
has been obtained (curarisation by the anaesthesiologist), the distal end of the tmm
is passed through the tunnel ([figure 3]).
Figure 3
The muscle is positioned to replace/augment the anterior and lateral part of the deltoid
muscle.
The midaxillar incision is closed over a little drain; the muscle is inserted unto
the lateral clavicular rim unto the remaining dm with the arm positioned in 90° abduction
and 20° flexion. This fixation is realized by several Maxon 2/0 sutures passed behind
the rim suture on the tmm, so that a tight connection to the dm insertion unto the
clavicle might be obtained.
An abduction orthesis is maintained for 6 weeks and than progressive active mobilisation
is performed.
Results
In a continous series from July 2005 to March 2009, we performed the tmm transfer
in 17 children aged 3 to 17 years, and obtained improvements both in shoulder abduction
(between 15 and 70°) and flexion (50°) after a follow-up ranging from 5 to 36 months.
One muscle was lost probably by injury to the neurovascular bundle in a rather fibrotic
muscle with difficult dissection; the completely necrotized muscle had to be withdrawn
after 1 week. There were no other drawbacks.
Discussion
We believe that the tmm transfer, based on its unique vascular pedicle (a branch of
the subscapular artery) and nerve (a direct motor branch from the posterior cord)
as a monopedicular transfer (maintaining the proximal tendon insertion), is functionally
an interesting option to enhance muscle strength, and to counteract co-contractions
at the shoulder level in children with obpp sequelae.
This transfer might also be used to enhance the muscle bulk in a cranial trapezius
muscle transfer or in a modified Hoffer transfer for lateral rotation of the shoulder.
The critical point of the surgery is the identification of the unique neurovascular
bundle and the transposition through a previously widened tunnel over the humerus,
and under the remaining dm, without compromising the muscle viability.
Our good preliminary functional results encourage us to further develop and advise
this transposition technique.
Summary
We present a new surgical technique, using the monopolar teres major muscle transfer
to enhance shoulder function in children suffering from sequelae of upper obstetric
brachial plexus palsy.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
JB developed the technique and wrote the manuscript; COP participated in the surgeries
and in the clinical follow-up of patients. Both authors read and approved the final
version of the manuscript.
