J Huazhong Univ Sci Technol［Med Sci］

37(6):933-937,2017
DOI https://doi.org/10.1007/s11596-017-1830-9
J Huazhong Univ Sci Technol [Med Sci］ 37(6):2017 933

Transposition of Branches of Radial Nerve Innervating Supinator to

Posterior Interosseous Nerve for Functional Reconstruction of Finger
and Thumb Extension in 4 Patients with Middle and Lower Trunk
Root Avulsion Injuries of Brachial Plexus

Xia WU (吴 霞), Xiao-bing CONG (丛小兵), Qi-shun HUANG (黄启顺)#, Fang-xin AI (艾方兴), Yu-tian LIU (刘玉田),
Xiao-cheng LU (鲁晓乘), Jin LI (李 进), Yu-xiong WENG (翁雨雄), Zhen-bing CHEN (陈振兵)
Department of Hand Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan
430030, China

© Huazhong University of Science and Technology and Springer-Verlag GmbH Germany 2017

Summary: This study aimed to investigate the reconstruction of the thumb and finger extension func-
tion in patients with middle and lower trunk root avulsion injuries of the brachial plexus. From April
2010 to January 2015, we enrolled in this study 4 patients diagnosed with middle and lower trunk root
avulsion injuries of the brachial plexus via imaging tests, electrophysiological examinations, and clinical
confirmation. Muscular branches of the radial nerve, which innervate the supinator in the forearm, were
transposed to the posterior interosseous nerve to reconstruct the thumb and finger extension function.
Electrophysiological findings and muscle strength of the extensor pollicis longus and extensor digitorum
communis, as well as the distance between the thumb tip and index finger tip, were monitored. All pa-
tients were followed up for 24 to 30 months, with an average of 27.5 months. Motor unit potentials
(MUP) of the extensor digitorum communis appeared at an average of 3.8 months, while MUP of the
extensor pollicis longus appeared at an average of 7 months. Compound muscle action potential (CMAP)
appeared at an average of 9 months in the extensor digitorum communis, and 12 months in the extensor
pollicis longus. Furthermore, the muscle strength of the extensor pollicis longus and extensor digitorum
communis both reached grade Ⅲ at 21 months. Lastly, the average distance between the thumb tip and
index finger tip was 8.8 cm at 21 months. In conclusion, for patients with middle and lower trunk inju-
ries of the brachial plexus, transposition of the muscular branches of the radial nerve innervating the su-
pinator to the posterior interosseous nerve for the reconstruction of thumb and finger extension function
is practicable and feasible.
Key words: brachial plexus; peripheral nerve; supinator; trauma; nerve transposition

For patients with middle and lower trunk root avul- forearm still exist in patients with middle and lower
sion injuries of the brachial plexus, shoulder and elbow trunk injuries of the brachial plexus. Furthermore, the
functions, as well as wrist extensions, are well pre- posterior interosseous nerve innervating the extensor
served[1–3]. The goal of treatment is to recover the flexion pollicis longus and extensor digitorum communis, and
and extension of fingers and thumbs. Such recovery can the muscular branches innervating the supinator, both
be well achieved via Oberlin’s procedure or brachialis originate from the radial nerve. Considering their ho-
transposition[4, 5]. However, finger and thumb extension mology, it might be possible to transpose the muscular
functions cannot be reconstructed via conventional ten- branches of the radial nerve innervating the supinator to
don transposition. Reconstruction of finger and thumb repair the posterior interosseous nerve in order to recon-
extension, although achievable via muscle transplanta- struct the finger and thumb extension function. In the
tion[6], is both physically and mentally unacceptable for present study, we attempted to use this new surgical
patients with severe trauma. For patients with middle and procedure to treat 4 patients with middle and lower trunk
lower trunk injuries of the brachial plexus, the finger and root avulsion injuries of the brachial plexus, and favor-
thumb flexion and extension functions are missing, but able results were obtained.
the pronation and supination of the forearm still exist.
The nerve innervating the pronator teres originates from 1 SUBJECTS AND METHODS
the lateral head of the median nerve, which corresponds
to nerve roots C5 and C6. The nerve innervating the su- From April 2010 to January 2015, 4 patients with
pinator also originates from nerve roots C5 and C6[3, 7]. middle and lower trunk root avulsion injuries of the bra-
Hence, the pronation and supination functions of the chial plexus were enrolled in this study. Their clinical
data are shown in table 1. All patients showed positive
Horner’s signs. Root avulsion injuries were confirmed by
Xia WU, E-mail: 632792694@qq.com
# magnetic resonance (MR), electromyogram (EMG), and
Correspondence author, E-mail: hqsw@hotmail.com
934 J Huazhong Univ Sci Technol [Med Sci］ 37(6):2017

clinical surgeries. The compound muscle action potential EMG. Additionally, the duration from injury to surgery
(CMAP) of the supinator was normal, as examined by was less than 6 months in all cases.

Table 1 Clinical data of the 4 patients

Case number Age (years) Gender Cause of injury Injured arm Horner’s Time from injury to
sign surgery (months)
1 24 Male Twist injury by machine Left + 3
2 28 Male Car accident Left + 5
3 45 Male Motorcycle accident Right + 4
4 35 Male Twist injury by machine Right + 5

Due to brachial plexus injuries, we applied en- the posterior interosseous nerve close to where the mus-
dotracheal intubation and inhalation anesthesia for all the cular branches of the radial nerve exited. The 2 muscular
4 patients. Patients were placed in a supine position with branches of the radial nerve were sutured to the distal
the injured arm abducted and pronated on the operating end of posterior interosseous nerve with 9/0 prolene
table. A 10-cm incision was made at the proximal end of stitches under 4× magnification. The operated arm was
the posterior side of the forearm. The inferior margin of fixed for 3 weeks by plaster slab with the wrist extended
the supinator and posterior interosseous nerve was ex- and elbow flexed. Patients were followed up every 3
posed after access through the space between the exten- months. During these follow ups, we examined the elec-
sor digitorum communis and extensor carpi radialis bre- trophysiology and muscle strength of the extensor polli-
vis. The superficial head of the supinator was pulled cis longus and extensor digitorum communis, as well as
proximally, and the muscular branches exiting from the the range of the extension of metacarpophalangeal joints.
trunk of the deep branch of the radial nerve was searched
between the 2 heads of the supinator. There were nor- 2 RESULTS
mally 3–5 muscular branches[8, 9], 2 of which were usu-
ally thick and big. These 2 muscular branches were All 4 patients were followed up for an average of
separated. Intense contraction of the supinator was visi- 27.5 months after surgery (24–30 months). At 24 months
ble after electric stimulation of the muscular branches postoperatively, substantial improvement of finger ex-
intraoperatively, which verified the integrity and function tension had been achieved (M3) for extensor digitorum
of the separated muscular branches. On the other hand, communis, extensor pollicis longus, and extensor carpi
electric stimulation of the posterior interosseous nerve ulnaris, (M2) for abductor pollicis longus. The supination
did not result in any electrophysiological activities of the function of the forearm still existed in all 4 patients. Fol-
extensor pollicis longus and extensor digitorum commu- low-up results are shown in table 2. The photographs of
nis, which again confirmed the functional loss of the the recovery of thumb/finger extension in one patient 27
posterior interosseous nerve. We then cut off the muscu- months after operation can be seen in fig. 1.
lar branches near the supinator, and proximally cut off

Fig. 1 Photographs showing the recovery of thumb/finger extension 27 months after transfer of the supinator motor branch to the-
posterior interosseous nerve in case 1
A: before the operation; B: MR demonstrates C8 and T1 root avulsion, cerebrospinal leakage; C: the avulsion of C8 and T1
nerve roots during operation; D: the posterior interosseous nerve (yellow) and muscular branches of the radial nerve innervat-
ing the supinator (red and green); E: suturing the nerve end directly; F: 27 months post-operation
J Huazhong Univ Sci Technol [Med Sci］ 37(6):2017 935
Table 2 Follow-up results
Time (m)
Case Items 3 6 9 12 15 18 21 24 27 30
1 EMG
EDC MUP MUP± CMAP+ CMAP↑ CMAP↑ CMAP↑ Simple Simple Simple/mixed Mixed
EPL MUP– MUP– MUP± MUP+ CMAP+ CMAP Simple Simple Simple Sim-
ple/mixed
Muscle
strength
EDC M0 M0 M1 M2 M2 M3 M3 M3 M3 M3
EPL M0 M0 M0 M1 M1 M2 M2 M3 M3 M3
Distance 0 0 0 1 1 3 5 8 8 9
(cm)
2 EMG
EDC MUP± MUP+ CMAP+ CMAP↑ CMAP↑ Simple Simple/mixed Mixed
EPL MUP– MUP+ MUP+ CMAP+ CMAP↑ Simple Simple Sim-
ple/mixed
Muscle
strength
EDC M0 M1 M2 M2 M3 M3 M3 M3
EPL EPL M0 M0 M1 M2 M2 M3 M3
Distance 0 0 1 2 3 5 8 8
(cm)
3 EMG
EDC MUP± MUP+ CMAP+ CMAP↑ CMAP↑ Simple Simple Simple/mixed Mixed Mixed
EPL MUP– MUP± MUP+ CMAP+ CMAP↑ Simple Simple/mixed Mixed Mixed Mixed
Muscle
strength
EDC M0 M0 M1 M2 M2 M3 M3 M3 M3 M3
EPL EPL M0 M0 M0 M1 M1 M2 M2 M3 M3
Distance 0 0 1 1 2 3 6 7 9 10
(cm)
4 EMG
EDC MUP± MUP+ CMAP+ CMAP↑ CMAP↑ Simple/mixed Simple/mixed Simple
EPL MUP– MUP± MUP+ CMAP+ CMAP↑ Simple/mixed Simple Simple
Muscle
strength
EDC M0 M0 M1 M2 M2 M3 M3 M3
EPL M0 M0 M0 M1 M1 M2 M2 M3
Distance 0 0 0 1 1 3 5 8
(cm)
EDC: extensor digitorium communis; EPL: extensor pollicis longus

3 DISCUSSION restored via procedures like tenodesis[11, 12]. However, it

is still challenging to achieve active dorsiflexion of the
For patients with middle and lower trunk root avul- metacarpophalangeal joints and thumb with these meth-
sion injuries of the brachial plexus, the functions of the ods. Also, the thumb and fingers cannot fully stretch,
shoulder and elbow are well preserved, and most func- hence affecting grasping functions.
tions of the wrist still exist[1, 2, 10]. This is because the Anatomical research has demonstrated that the su-
nerves innervating the flexor carpi radialis and extensor pinator can be divided into the deep head and superficial
carpi radialis longus originate from the upper trunk of the head. There are 4–5 muscular branches of the radial
brachial plexus (C5, C6). Thus, the major problems with nerve innervating the supinator, which provides the ana-
such injuries are disorders in the flexion, extension, ad- tomical basis for the transposition of the muscular
duction, abduction, and rotation of the metacarpopha- branches to the posterior interosseous nerve to recon-
langeal joints and interphalangeal joints of patients’ struct finger and thumb extension. Furthermore, transpo-
hands. With the help of Oberlin’s procedure of nerve sition of 2 relatively large branches will not greatly in-
transposition, transposition of the brachialis tendon, and fluence the supination of the forearm[13, 14]. Supination of
functioning free muscle transplantation (such as gracilis), the forearm is also observed when the biceps contracts
problems in the flexion and extension of metacarpopha- and the elbow flexes[15]. Therefore, transposition of part
langeal joints and interphalangeal joints of the hands can of the muscular branches would not affect the supination
be well solved. For example, finger extension can be of the forearm in patients. In the present study, we ob-
936 J Huazhong Univ Sci Technol [Med Sci］ 37(6):2017

served the maintenance of supination during the fol- quinti proprius, and extensor digitorum communis are all
low-up period. capable of extending the metacarpophalangeal joints.
The muscular branches innervating the supinator Additionally, the function of the extensor carpi radialis
originate from the deep branch of the radial nerve at the longus is usually normal. Therefore, observations on the
proximal end of the Froshi arch, and lie between the deep recovery of muscles with overlapping functions could be
and superficial head of the supinator together with the abandoned. This explains why functional recovery of
terminal branch of the radial nerve and posterior interos- only the extensor pollicis longus and extensor digitorum
seous nerve. The 3 branches travel distally through the communis was monitored in this study.
same intermuscular space. Additionally, the muscular The extensor digitorum communis is mainly re-
branches of the radial nerve and posterior interosseous sponsible for the extension of metacarpophalangeal
nerve are close together. It is rather easy to distinguish joints, and the extension of interphalangeal joints mainly
them if they are accessed through the space between the relies on the lateral tendon bundle composed of the in-
extensor digitorum communis and extensor carpi radialis terosseus and lumbricalis. When the middle and lower
brevis intraoperatively, and then dissected and separated trunk of the brachial plexus is injured, the intrinsic mus-
between the deep and superficial head of the supinator. cles of the hand are paralyzed and active finger extension
Before cutting off the muscular branches for transposi- of interphalangeal joints is lost. Even if the metacarpo-
tion, intraoperative EMG must be conducted to confirm phalangeal joints extend to reach a degree of 0°, fingers
the maintenance of function of the muscular branches still cannot extend unbent. Therefore, middle and lower
and the complete functional loss of the posterior interos- trunk injury of the brachial plexus leads to the loss of
seous nerve. both flexion and extension of fingers. Although flexion
Furthermore, when cutting off the nerves, the prin- of the thumb and fingers can be restored with transposi-
ciple of having a distal donor and proximal receptor must tion of tendons or nerves, they remain incapable of ex-
be followed for nerve transposition. The donor nerve tending. Apart from that, the tip of the thumb is stuck
should be cut off distally near the muscle, whereas the close to the tip of the index finger, making it impossible
receptor nerve should be cut off proximally close to the to actively grasp due to the very small space between the
trunk in order to ensure no tension of the suture after digits. Thus, the grasping function of the hand cannot be
nerve transposition[16, 17]. Since the muscular branches well restored with this method.
innervating the supinator are in the same intermuscular However, transposition of the muscular branches
space with the posterior interosseous nerve, they were innervating the supinator to the posterior interosseous
directly transposed to the posterior interosseous nerve. nerve could restore the function of the extensor pollicis
The procedure is rather simple and convenient, with no longus and extensor digitorum communis, making the
need for transplantation. However, if it is difficult to thumb and fingers capable of dorsiflexion. Subsequently,
dissect and separate the muscular branches in the inter- the space between the thumb and other fingers would be
muscular space of the supinator, we recommend making larger, permitting the hand to properly grasp objects. In
another incision at the proximal end of the palmar side of the present study, we conducted an average of 27.5
the forearm. Then, the muscular branches can be dis- months of follow-up, observing the distance between the
sected and separated at the trunk of the deep branch of thumb tip and index finger tip reaching 8.8 cm. Ulti-
the radial nerve at the proximal end of the Froshi arch. mately, active grasping function was greatly improved.
Furthermore, an intraoperative EMG must be conducted However, further studies are required to investigate
before cutting off the nerves. whether it is possible to directly transpose the muscular
The diameters of muscular branches in transposi- branches innervating the supinator to the muscular
tion were found to be rather thinner than that of the pos- branches innervating extensor pollicis longus and exten-
terior interosseous nerve. The nerve diameter was only sor digitorum communis in order to improve the muscle
half that of the posterior interosseous nerve, even when 2 strength of the extensor pollicis longus and extensor
muscular branches were transposed, which was consis- digitorum communis.
tent with the findings of Zhang and Bertelli’s study[18, 19]. To sum up, for patients with middle and lower trunk
The number of nerve fibers originating from the donor injuries of the brachial plexus, transposition of the mus-
nerve was limited, and part of the nerves, after being cular branches of the radial nerve innervating the supi-
transposed to the posterior interosseous nerve, grew to- nator to the posterior interosseous nerve for the restora-
ward and innervated the flexor carpi ulnaris, extensor tion of thumb and finger extension function is practicable
digiti quinti proprius, musculus extensor indicis proprius, and feasible.
and extensor pollicis brevis. Hence, the number of nerve
fibers innervating the extensor pollicis longus and ex- Conflict of Interest Statement
tensor digitorum communis were further reduced. The authors report no conflicts of interest in this study.
Therefore, the muscle strength of the extensor pollicis
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