Distal nerve transfer from the median nerve lumbrical fibers to the distal ulnar nerve motor branches in the palm: An anatomical cadaveric study

Abstract

Background The aim of the current study is to investigate the first and second lumbrical nerves as potential fibers donors to the deep motor branch of the ulnar nerve to avoid intrinsic atrophy in high ulnar nerve injuries. Methods Sixteen fresh frozen cadaveric hands were dissected, the radial lumbrical nerves accessed, and a coaptation, either in reverse end‐to‐side or in double end‐to‐side through a bridge nerve graft, was created to the deep motor branch of ulnar nerve. Semithin sections were taken from samples of donor and recipient nerves for qualitative (nerve architecture) and quantitative studies (fiber count and donor/recipient ratio). Results The first lumbrical showed a robust trunk and a superior axon density (9,126.50 ± 2,923.41 axons/mm2) to the ulnar motor branch (7,506.50 ± 1,137.50 axons/mm2 distal to the opponens tunnel and 7,947.75 ± 1,741.24 axons/mm2 before its terminal branching); the ulnar motor branch showed a higher axon number (2,633.51 ± 410.00 distal to the opponens tunnel and 2,345.75 ± 2,101.56 before its terminal branching) than the first lumbrical (1,410.56 ± 823.89); section areas occupied by axons were higher in proximal (0.20 ± 0.16) and distal (0.26 ± 0.20) ulnar samples than the first lumbrical (0.17 ± 0.16). Donor/recipient ratio first lumbrical/deep motor branch of the ulnar nerve were 1:1.86 (distal to the opponens tunnel) and 1:1.67 (at its terminal branching); data about the second lumbrical were ruled out because of bias. Conclusions A transfer from the first lumbrical nerve to the deep motor branch of the ulnar nerve in palm is suitable to avoid intrinsic atrophy.

Lumbrical Muscles Neural Branching Patterns: A Cadaveric Study With Potential Clinical Implications

“…Lumbrical muscle innervation occurred typically in the proximal to middle third junctions of the muscle. 23 In the current study, a dual innervation was solely observed for LM 2 , while Lauritzen and Szabo 18 observed LM dual innervation in 68% (of LM 3 in 64% and of LM 1 and LM 2 in 4%, per each). No dual innervation of LM 4 was observed in the current study.…”

Nerve transfers in distal forearm and in the hand

“…In 2017, Colonna et al [36] suggested using the branch for the first lumbrical as a babysitter for the deep motor branch of the ulnar nerve to avoid intrinsic atrophy. This hypothesis was based on anatomical studies and qualitative and quantitative analysis of nerve fibers.…”

Comments on “Lumbrical Muscles Neural Branching Patterns: A Cadaveric Study With Potential Clinical Implications”

“…3 A previous study demonstrated the microscopic feasibility of nerve coaptation of the motor branches of the first lumbrical muscles (LM) as donor nerve candidates to restore the function of adductor pollicis muscle (ADP) and to achieve a passing prehensile function. 4 The authors reported the results of a cadaveric study in 8 patients (5 men and 3 women) demonstrating different LM innervation patterns, in particular the relatively common presence of double branches innervation in 62.5% and dual innervation of the second lumbrical muscle (LM2) in 12.5%.…”

“…A previous study demonstrated the microscopic feasibility of nerve coaptation of the motor branches of the first lumbrical muscles (LM) as donor nerve candidates to restore the function of adductor pollicis muscle (ADP) and to achieve a passing prehensile function. 4…”