Injuries to the median and ulnar nerves at the elbow are common. Tension-free suturing offers the best results. For significant nerve loss, autografting is recommended. Flexion suturing of the elbow described by few authors is a promising alternative, but little studied.

We sought to elucidate the conditions of direct suturing of median and ulnar nerves defects at elbow. We aimed to establish a correlation among the defect length, degree of elbow flexion, and eventual need for wrist immobilization.

We performed an experimental study by completing bilateral dissection of the median and ulnar nerves with transposition of this one in 3 cadavers resulting in a total of 6 ulnar nerve lesions and 6 median nerve lesions studied. For each defect, a direct tensionless suture was performed with elbow flexion. Next, the elbow was progressively extended until the tension been unacceptable in the 3 positions of the wrist. The nerve defect length correlated with the degree of elbow flexion and wrist position required to perform and protect the installed sutures.

For median nerve, a 90° elbow flexion allowed for direct suturing of defects until 35mm, wrist in neutral position. A bowstringing effect was noted since 25mm of nerve defect. For ulnar nerve the transposition permits tensionless suture until 20mm of defect without necessity of elbow flexion. A 90° elbow flexion allowed for direct suturing of defects until 39mm, wrist in neutral position. Wrist extension placed tension on the nerve suture for both nerves.

The benefits of direct suturing of the median and ulnar nerves at the elbow does not lie in improved functional results. In the upper limb, delayed direct suturing showed no great difference in functional results compared with autografting. Only primary suturing has shown better results. This approach may be considered in differents situations. Firstly, it can be used for primary suturing without the need for autologous grafting. Secondly, it can be used to manage grafts in cases of polytrauma. Thirdly, it can help avoid donor-site harvesting and morbidity in chronically painful patients. Finally, it can be a therapeutic option in children, to avoid the need for harvesting.

The results of this first anatomical study clarified the conditions for direct suturing of ulnar and median nerve defects associated with elbow and wrist flexion. This is an approach to consider for limited nerve defect to the elbow to allow primary suturing or when allograft harvesting is to be avoided.