The terminal branch of posterior interosseous nerve: a useful donor for digital nerve grafting

Posterior Interosseous Nerve Graft: Utilizing External Landmarks and Anthropometric Ratios to Predict Available Length for Digital Nerve Reconstruction in a Cadaveric Study

Objective:

In digital nerve defects that require grafting, autografts remain the efficacious option. The sensory posterior interosseous nerve (PIN) is an ideal choice as it is of similar caliber to digital nerves and leaves no donor morbidity upon resection. However, a finite length of harvestable PIN exists, and considerable variations of this length have been reported in the literature. There exists no predictive model to estimate this length. We sought to determine a method to accurately predict the available length of PIN based on individual patient anthropometry.

Methods:

A cadaveric dissection study was performed in a fresh tissue laboratory. The length of the sensory branch of the PIN and various anthropometric measurements were made in respect to surface anatomy of the ulna to develop a predictable ratio for available PIN donor graft.

Results:

A total of 16 specimens were obtained. On average the length of the PIN was 5.7 cm (range: 3.3-9. cm) and the length of the ulna was 25.7 cm (range: 23.5-30.6 cm). The ratio of PIN to ulnar length was 0.222 ( r = 0.4651). Using one-fifth the length of the ulna, the mean predicted length of the PIN was 5.14 cm (range: 4.7-6.1 cm). On univariate analysis, there was no significant difference between the measured and predicted PIN length ( P = .249).

Conclusion:

An anthropometric ratio predicated on reproducible surface anatomy of the ulna is a useful tool in predicting the sensory PIN length. Such a prediction may be a useful in guiding patient discussions concerning surgical options for digital nerve reconstruction.

Transfer of the extensor indicis proprius branch of posterior interosseous nerve to reconstruct ulnar nerve and median nerve injured proximally: an anatomical study

Proximal or middle lesions of the ulnar or median nerves are responsible for extensive loss of hand motor function. This occurs even when the most meticulous microsurgical techniques or nerve grafts are used. Previous studies had proposed that nerve transfer was more effective than nerve grafting for nerve repair. Our hypothesis is that transfer of the posterior interosseous nerve, which contains mainly motor fibers, to the ulnar or median nerve can innervate the intrinsic muscles of hands. The present study sought to investigate the feasibility of reconstruction of the deep branch of the ulnar nerve and the thenar branch of median nerve by transferring the extensor indicis proprius branch of the posterior interosseous nerve obtained from adult cadavers. The results suggested that the extensor indicis proprius branch of the posterior interosseous nerve had approximately similar diameters and number of fascicles and myelinated nerve fibers to those of the deep branch of ulnar nerve and the thenar branch of the median nerve. These confirm the feasibility of extensor indicis proprius branch of posterior interosseous nerve transfer for reconstruction of the deep branch of the ulnar nerve and the thenar branch of median nerve. This procedure could be a novel and effective method for the functional recovery of the intrinsic muscles of hands after ulnar nerve or median nerve injury.

Transfer of the radial nerve branch to the extensor carpi radialis brevis to the anterior interosseous nerve to reconstruct thumb and finger flexion

PURPOSE

To report our experiences reconstructing thumb and finger flexion in patients with extensive palsy of the upper limb by transferring the radial nerve branch to the extensor carpi radialis brevis (ECRB) to the anterior interosseous nerve (AIN).

METHODS

Within 8 months after injury, 4 patients with either a combined high median/ulnar nerve palsy or C7-T1 brachial plexus root avulsion underwent surgical reconstruction for thumb and finger flexion. As part of the reconstructive procedure, the branch of the radial nerve to the ECRB was transferred to the AIN.

RESULTS

At final evaluation, which averaged 13 months postoperatively, all patients had recovered full finger and thumb flexion, scoring M4 per Medical Research Council guidelines. Average grasp strength was 5 kg, and pinch strength was 2 kg. Even in anesthetic fingers and with their eyes closed, patients could correctly identify passive extension of their distal interphalangeal joints. Wrist extension was preserved in all patients.

CONCLUSIONS

In 4 patients, transfer of the branch of the radial nerve to the ECRB to the AIN predictably reconstructed thumb and finger flexion. Finger flexion also recovered in those fingers in which the flexor digitorum profundus was primarily innervated by the ulnar nerve. Despite extended sensory deficits, patients ultimately were able to use their hands regularly in daily life.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Important anatomical relationships of the posterior interosseous nerve in the distal forearm for surgical planning: a cadaveric study

A thorough knowledge of the anatomy of the terminal branch of the posterior interosseous nerve (PIN) and its relationship to the anterior interosseous nerve (AIN) is essential in facilitating regional anesthetic blocks and planning surgical exposures for wrist surgery and arthrodesis of wrist and proximal row carpectomy. This cadaveric study focused on the anatomy and course of the PIN and its anatomical relationships at the distal forearm. Thirty embalmed cadaver forearms were dissected using microsurgical techniques. A structured pro forma was used to collect data. The PIN was consistently found in the fourth extensor compartment in all specimens. The last motor branch was given off 46.9 ± 8.4 mm (mean ± standard deviation) from the most proximal part of the ulnar head. The AIN was found lying consistently on the anterior aspect of the interosseous membrane, being on average 2.8 ± 0.2 mm (mean ± standard deviation) from the PIN. This knowledge will facilitate the planning of diagnostic and therapeutic procedures associated with the wrist.

Posterior interosseus nerve vs. medial cutaneous nerve of the forearm: differences in digital nerve reconstruction

Digital nerve defects are common in hand trauma and for primary or secondary nerve reconstruction, the autologous nerve graft remains the gold standard. This study compares the regeneration results and donor side morbidity of either the posterior interosseus nerve (PIN) graft or the medial antebrachial cutaneous nerve (MACN) graft. 16 patients (group A, age 43 ± 13 years) with digital nerve defects were treated with a PIN graft and 12 patients (group B, age 40 ± 15 years) received a MACN graft. The average nerve gap was 22 mm in each group. After a follow-up of 15 ± 8 months in group A, S4-sensibility were measured in 9 cases, S3+ in 5 cases and in 1 case S2 and S0. Up to an inconspicuously scar in projection of the fourth extensor-tendon compartment, there was no significant donor side morbidity. In group B, a S4-senibility has been obtained in 4 cases, S3+ in 5 cases, S3, S2 and S0 in each 1 case after a follow-up of 16 ± 11 months. Regarding the donor side morbidity, almost all patients complained about a disturbing scar formation and unpleasant paresthesia at the forearm down to the rascetta. Neuroma-associated pain has been detected in 4 cases. Although there has been no significant difference in terms of nerve regeneration, we recommend the use of the PIN graft for digital nerve reconstruction, since harvesting this nerve is fast and easy and without any donor side morbidity compared to the MACN graft.

Desensitizing the posterior interosseous nerve alters wrist proprioceptive reflexes

PURPOSE

The presence of wrist proprioceptive reflexes after stimulation of the dorsal scapholunate interosseous ligament has previously been described. Because this ligament is primarily innervated by the posterior interosseous nerve (PIN) we hypothesized altered ligamento-muscular reflex patterns following desensitization of the PIN.

METHODS

Eight volunteers (3 women, 5 men; mean age, 26 y; range 21-28 y) participated in the study. In the first study on wrist proprioceptive reflexes (study 1), the scapholunate interosseous ligament was stimulated through a fine-wire electrode with 4 1-ms bipolar pulses at 200 Hz, 30 times consecutively, while EMG activity was recorded from the extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris, with the wrist in extension, flexion, radial deviation, and ulnar deviation. After completion of study 1, the PIN was anesthetized in the radial aspect of the fourth extensor compartment using 2-mL lidocaine (10 mg/mL) infiltration anesthesia. Ten minutes after desensitization, the experiment was repeated as in study 1. The average EMG results from the 30 consecutive stimulations were rectified and analyzed using Student's t-test. Statistically significant changes in EMG amplitude were plotted along time lines so that the results of study 1 and 2 could be compared.

RESULTS

Dramatic alterations in reflex patterns were observed in wrist flexion, radial deviation, and ulnar deviation following desensitization of the PIN, with an average of 72% reduction in excitatory reactions. In ulnar deviation, the inhibitory reactions of the extensor carpi ulnaris were entirely eliminated. In wrist extension, no differences in the reflex patterns were observed.

CONCLUSIONS

Wrist proprioception through the scapholunate ligament in flexion, radial deviation, and ulnar deviation depends on an intact PIN function. The unchanged reflex patterns in wrist extension suggest an alternate proprioceptive pathway for this position. Routine excision of the PIN during wrist surgical procedures should be avoided, as it alters the proprioceptive function of the wrist.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Digital nerve grafting using the terminal branch of posterior interosseous nerve: a report of three cases

We report three cases of digital nerve grafting using the terminal branch of posterior interosseous nerve.

The anatomy of the posterior interosseous nerve as a graft

Thirty upper limbs from skeletally mature embalmed cadavers were studied to determine the anatomic reliability of the posterior interosseous nerve as a donor nerve graft. The posterior interosseous nerve branches 0.43 +/- 0.52 cm from the distal edge of the superficial head of the supinator and 8 +/- 1.6 cm from the lateral epicondyle form a common leash. There are 6 branches, which are arranged from the ulnar to the radial side at their origin from this leash. The first and second branches supply the extensor digitorum communis, the third branch supplies the extensor carpi ulnaris, the fourth branch supplies the extensor digiti minimi, and the fifth branch arises from the undersurface of the common leash and divides into 2 sub-branches (medial and lateral) 10.1 +/- 3.2 cm distal to the lateral epicondyle and 12.8 +/- 2.2 cm proximal to Lister's tubercle. These 2 sub-branches make an inverted V shape around the extensor pollicis longus. The medial branch supplies the extensor pollicis longus and extensor indicis proprius. The lateral branch supplies the extensor pollicis longus and extensor pollicis brevis and ends at the wrist capsule. At a mean distance of 8.1 +/- 1.2 cm proximal to Lister's tubercle the lateral sub-branch gives off its last muscular branch to the extensor pollicis longus and becomes a pure sensory terminus. As the terminal part of the lateral sub-branch approaches the wrist capsule it expands at a mean distance of 1.9 +/- 0.5 cm proximal to Lister's tubercle. The sixth branch arises from the radial side of the common leash and divides into 3 sub-branches. The first sub-branch supplies the abductor pollicis longus and extensor pollicis brevis, the second supplies the abductor pollicis longus, and the third supplies the superficial head of the supinator. This study showed that the mean length obtainable for harvesting the lateral sub-branch of the fifth branch of the posterior interosseous nerve is 6.2 +/- 0.7 cm, which represents the length of the nerve between the last muscular branch to the extensor pollicis longus to the point at which the nerve expands.