Recovery of Motor Function after Mixed and Motor Nerve Repair with Processed Nerve Allograft

Bauback Safa 1, Jaimie T. Shores 2; John V. Ingari 2, Renata V. Weber 3, Mickey Cho 4, Jozef Zoldos 5, Timothy R. Niacaris 6, Leon J. Nesti 7, Wesley P. Thayer 8; Gregory M. Buncke 1

1 The Buncke Clinic, San Francisco, USA; 2 Johns Hopkins University, Baltimore, USA; 3 Multi-Disciplinary Specialists, Rutherford, USA; 4 San Antonio Military Medical Center; Fort Sam Houston,

USA; 5 Phoenix, USA; 6 JPS Health Network, Fort Worth, USA; 7 Walter Reed National Military Medical Center; Bethesda, USA; 8Vanderbilt University Medical Center; Nashville, USA

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References

Severe trauma to the upper extremities often results in the transection of mixed and motor peripheral nerves. Without surgical management, these transection injuries result in functional loss that can seriously affect the patient’s overall quality of life. Clinical data demonstrate that processed nerve allograft (PNA) is safe and results in positive functional outcomes for the reconstruction of nerve gaps up to 70 mm in length. However, these studies mostly report on sensory outcomes.

The RANGER® Registry is an ongoing observational study on the use and outcomes of processed nerve allografts (Avance® Nerve Graft, AxoGen, Inc.). Here we report on motor recovery outcomes for nerve injuries repaired acutely or in a delayed fashion with PNA and comparisons to historical controls in the literature.

Introduction

Methods

Results

• Processed nerve allografts provided functional motor recovery when used for mixed and motor nerve repairs.

• Outcomes compare favorably to historical controls in the literature for nerve autograft and exceed those for hollow tube conduit.

• Processed nerve allograft may be considered as an option when reconstructing major peripheral nerve injuries.

Conclusions

• The RANGER® database was queried for acute mixed and motor nerve injuries in the upper extremities, head and neck.

• Inclusion:• Gaps ≥ 70mm• Documentation of ≥ six months of follow-

up in injuries at the wrist level• Documentation of ≥ 12 months of follow-up

in injuries proximal to wrist • Sufficient assessments to evaluate

functional outcomes (Table 1)• Meaningful recovery was defined as ≥M3 • Higher level of recovery was defined as ≥M4• Demographics, outcomes and covariate analysis

were performed to further characterize this sub-group.

Table 3. Summary of Outcomes by Gap Length

Chart 1. Label in 24pt Calibri.

Nerve Repaired Functional Assessments Included

Median nerve,

forearm

Flexion of the thumb, index and

middle fingers as well as the ability to

form a composite fist

Median nerve, wrist

Palmar abduction of the thumb;

flexion of the index and middle

fingers at metacarpophalangeal joints

Radial nerve, upper

arm

Extension of the wrist; abduction of

the wrist

Radial nerve, forearm Supination of the forearm

Ulnar nerve, forearmFlexion of the ring and small fingers at

distal interphalangeal joints

Ulnar nerve, wrist

Key pinch; abduction of small finger;

flexion of ring and small fingers at

metacarpophalangeal joints

Musculocutaneous

nerve, biceps branchElbow flexion

Spinal accessory

nerveShoulder elevation

Facial nerve, buccal,

mandibular and

zygomatic branches

Lip movement (whistling, smiling,

puckering and pouting the lip)

Table 1. Functional Assessments by Nerve Repair

AllGap Length (mm)

10-25 26-49 ≥50

No. of Repairs 36 16 13 7

Age (years) 39 ± 19 41 ± 20 44 ± 20 28 ± 9

Pre-op Interval (days)a

8.5 (0, 133)

7.5 (0, 96)

5 (0, 133)

45 (9, 125)

Follow-up Duration (days)

594 ±441

619 ±347

506 ±314

698 ±719

Mechanism of Injuryb

LacerationComplexSurgical resection

19134

1132

652

250

Meaningful Recovery (MR)

27 11 10 6

%MR 75% 69% 77% 86%a Pre-op interval is presented as Median (Min., Max.)b Laceration includes sharp or blunt/saw laceration.

Complex injury includes: gunshot/blast, crush/compression, and avulsion. Surgical resection refers to surgical removal of either a neuroma or a tumor-involved nerve segment

.

No. of Repairs

Gap Length (mm)

MR %MR

Median Nerve 18 35 ± 21 15 83%

Ulnar Nerve 10 33 ± 21 4 40%

Radial Nerve 3 48 ± 14 3 100%

Musculocutaneous Nerve

1 15 ± 0 1 100%

Spinal Accessory Nerve

1 12 ± 0 1 100%

Facial Nerve 3 27 ± 2 3 100%

All 36 34 ± 20 27 75%

Results

Figure 2: Recovery of motor function in subject with the ulnar nerve injury

A. Recovery of finger abduction

B. Reinnervation of the hypothenar muscles allowing the 5th digit opposition with the thumb

C. Recovery of finger metacarpal-phalangealjoint flexion and interphalangeal joint extension of the small and ring fingers

Demographics and Repair:

• 33 subjects with 36 nerve repairs• The mean age was 39 ± 19 (16-77) years• The median time to repair was 8.5 (0 - 133) days• The mean graft length was 34 ± 20 (10 - 70) mm • The mean follow up was 594 ± 441 days

No significant differences were found in subject age, pre-operative interval or follow-up length among subgroups (P> 0.05, ANOVA test)

Outcomes:• Meaningful motor recovery = 75% of repairs • Higher thresholds of recovery = 53% of repairs

with ≥ 1 year of follow-up

• Subgroup analysis showed no differences between gap lengths or mechanism of injury (see Table 3)

• There were no related adverse events reported

Figure 1: Injury and repair of an ulnar nerve with processed nerve allograft

A. 16 year old female presented with lower limb ulnar nerve palsy after accidental laceration to the left forearm with a knife. Exploration 41days post-injury, the flexor carpi ulnaris and ulnar neurovascular bundle wasnearly completely transected and encased in scar.

B. Neurolysis of the ulnar nerve and resection to healthy fascicles resultingin a gap length of 23 mm.

C. Following repair using two 3-4mm diameter processed nerve allograft in a grouped fascicular fashion.

Table 2. Summary of Outcomes by Nerve

Disclosure: This study was supported through a research grant by AxoGen Corp.

Study Nerve Injury Positive Outcomes*

Frykman and Gramyk Ulnar/ Median 60- 80%

Kim and Kline Ulnar/Median 57- 67%

Brushart Ulnar/Median 73%-84%

Vastamaki et al. Ulnar 57%

He et al Upper 50%

Ruijs et al. Ulnar/Median 51%* As reported, based on individual study parameters for acceptable recovery:

M3-M5, S3-S4 by MRCC

Table 4. Historical Literature

FEESH 2018ePoster A-0537