Targeted Muscle Reinnervation in the Hand: Treatment and Prevention of Pain After Ray Amputation

Outcome measures used in peripheral nerve surgery for symptomatic neuroma in upper extremity amputations: A scoping review

Novel surgical treatments for painful neuromas are increasingly used, but determining which provides the greatest benefit has been difficult due to the inconsistent use of outcome measures. We mapped the current literature of outcome measures used to evaluate peripheral nerve surgery for the management of symptomatic neuromas in patients who underwent an adult-acquired upper extremity amputation (UEA). Medline, Embase, Cochrane, and CINAHL were searched for primary research written in the English language from inception to February 2023. The search yielded 1137 articles, of which 35 were included for final analysis. Studies varied in their assessment of pain, health-related quality of life (HRQOL), neurotrophic measures, psychological and sensorimotor function, highlighting a consensus on crucial domains but also revealing significant heterogeneity in the use and application of outcome measures among primary studies. Our findings highlight the need to establish common standards that reflect the best evidence and unique needs of the UEA population. This includes developing a core outcome set, utilizing multi-center trials, and maintaining flexibility to adapt to ongoing advancements in patient-reported outcome measures (PROMs) research.

Impact of Timing of Targeted Muscle Reinnervation on Pain and Opioid Intake Following Major Limb Amputation

BACKGROUND

Targeted muscle reinnervation (TMR) has been shown to play an important role in managing neuromas. However, the impact of the timing of TMR on pain visual analogue scale (VAS) scores or patient opioid use has not been thoroughly explored. We hypothesized that TMR performed acutely would lead to lower VAS scores and decreased opioid intake.

METHODS

Prospectively collected data from an amputation registry at a single institution were utilized to identify patients who underwent TMR. Acute TMR was defined as TMR performed within 1 month of the major limb amputation. Primary outcomes included VAS pain scores and patient-reported opioid consumption.

RESULTS

In all, 25 patients (26 limbs) were identified in the acute group, and 18 patients (18 limbs) were identified in the delayed group. At intermediate follow-up (between 4 and 8 months postoperatively) and at final follow-up, the average pain VAS score in the delayed TMR group was significantly higher than that in the acute group (5.2 vs. 1.9 at intermediate P = .01 and 6.2 vs. 1.9 at final P = .002). In all, 84% of the amputees overall were not consuming opioid medications at the time of final follow-up (79% acute, 88% delayed, P = .72). There were no statistically significant differences in opioid consumption between the acute and delayed group at intermediate follow-up (P = .35) or at final follow-up (P = .68).

CONCLUSIONS

TMR is an effective procedure to reduce pain following major limb amputation. Patients with TMR performed acutely had significantly lower VAS pain scores at both intermediate and final follow-up than patients with TMR performed in a delayed setting.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Pain and Functional Outcomes following Targeted Muscle Reinnervation: A Systematic Review

BACKGROUND

It is estimated that by 2050, a total of 3.6 million patients will be living with an amputation in the United States. The objective of this systematic review is to evaluate the effect of targeted muscle reinnervation (TMR) on pain and physical functioning in amputees.

METHODS

A literature search was performed on PubMed, Embase, and MEDLINE up to November 28, 2021. Clinical studies assessing the outcomes of TMR (pain, prosthesis control, life quality, limb function, and disability) were included.

RESULTS

Thirty-nine articles were included. The total number of patients who underwent TMR was 449, and 716 were controls. Mean follow-up was 25 months. A total of 309 (66%) lower-limb and 159 (34%) upper-limb amputations took place in the TMR group, the most common being below-knee amputations (39%). The control group included a total of 557 (84%) lower-limb and 108 (16%) upper-limb amputations; the greatest proportion being below-knee amputations in this group as well (54%). Trauma was the most common indication for amputation. Phantom limb pain scores were lower by 10.2 points for intensity ( P = 0.01), 4.67 points for behavior ( P = 0.01), and 8.9 points for interference ( P = 0.09). Similarly, residual limb pain measures were lower for cases for intensity, behavior, and interference, but they failed to reach significance. Neuroma symptoms occurred less frequently, and functional and prosthesis control outcomes improved following TMR.

CONCLUSION

The literature evidence suggests that TMR is a promising therapy for improving pain, prosthesis use, and functional outcomes after limb amputation.

Digital Nerve Management and Neuroma Prevention in Hand Amputations

BACKGROUND

Hand and digit amputations represent a relatively common injury affecting an active patient population. Neuroma formation following amputation at the level of the digital nerve can cause significant disability and lead to revision surgery. One method for managing digital nerves in primary and revision partial hand amputations is to perform interdigital end-to-end nerve coaptations to prevent neuroma formation.

METHODS

All patients with an amputation at the level of the common or proper digital nerves that had appropriate follow-up at our institution from 2010 to 2020 were included. Common or proper digital nerves were managed with either traction neurectomy or digital end-to-end neurorrhaphy. The primary outcome was the development of a neuroma. Secondary outcomes included revision surgery, complications, and visual analog pain scores.

RESULTS

A total of 289 nerves in 54 patients underwent hand or digital amputation in the study period. Thirteen hands with 78 nerves (27%) underwent direct end-to-end coaptation with a postoperative neuroma incidence of 12.8% compared with 22.7% in the 211 nerves that did not have a coaptation performed. Significantly fewer patients reported persistent pain if an end-to-end coaptation was performed (0% vs. 11.8%, P < .01). The prevalence of depression and workers compensation status was significantly higher in in patients with symptomatic neuromas than in patients without symptomatic neuromas (P < .01).

CONCLUSIONS

Digital nerve end-to-end neurorrhaphy is a method for neuroma prevention in partial hand amputations that results in decreased residual hand pain without increase complications. Depression and worker's compensations status were significantly associated with symptomatic neuroma formation.

Targeted Muscle Reinnervation: A Systematic Review of Nerve Transfers for the Upper Extremity

INTRODUCTION/BACKGROUND

Despite inspiring improvements in postamputation pain and prosthetic control, targeted muscle reinnervation (TMR) continues to be underused. With some consistency for recommended nerve transfers developing in the literature, it is necessary to systematize these techniques and simplify their incorporation into routine amputation and neuroma care. This systematic review explores the coaptations reported in the literature to date.

METHODS

A systematic review of the literature was performed to collect all reports describing nerve transfers in the upper extremity. The preference was directed toward original studies presenting surgical techniques and coaptations used in TMR. All target muscle options were presented for each nerve transfer in the upper extremity.

RESULTS

Twenty-one original studies describing TMR nerve transfers throughout the upper extremity met inclusion criteria. A comprehensive list of transfers reported for major peripheral nerves at each upper extremity amputation level was included in tables. Ideal nerve transfers were suggested based on convenience and frequency with which certain coaptations were reported.

CONCLUSIONS

Increasingly frequent studies are published with convincing outcomes with TMR and numerous options for nerve transfers and target muscles. It is prudent to appraise these options to provide patients with optimal outcomes. Certain muscles are more consistently targeted and can serve as a baseline plan for the reconstructive surgeon interested in incorporating these techniques.

Failed Targeted Muscle Reinnervation: Findings at Revision Surgery and Concepts for Success

Although it was initially described for improved myoelectric control, targeted muscle reinnervation (TMR) has quickly gained popularity as a technique for neuroma control. With this rapid increase in utilization has come broadening indications and variability in the described technique. As a result, it becomes difficult to interpret published outcomes. Furthermore, there is no literature discussing the management of failed cases which are undoubtedly occurring.

Defect Coverage after Forequarter Amputation—A Systematic Review Assessing Different Surgical Approaches

Autologous fillet flaps are a common reconstructive option for large defects after forequarter amputation (FQA) due to advanced local malignancy or trauma. The inclusion of osseous structures into these has several advantages. This article therefore systematically reviews reconstructive options after FQA, using osteomusculocutaneous fillet flaps, with emphasis on personalized surgical technique and outcome. Additionally, we report on a case with an alternative surgical technique, which included targeted muscle reinnervation (TMR) of the flap. Our literature search was conducted in the PubMed and Cochrane databases. Studies that were identified were thoroughly scrutinized with regard to relevance, resulting in the inclusion of four studies (10 cases). FQA was predominantly a consequence of local malignancy. For vascular supply, the brachial artery was predominantly anastomosed to the subclavian artery and the brachial or cephalic vein to the subclavian or external jugular vein. Furthermore, we report on a case of a large osteosarcoma of the humerus. Extended FQA required the use of the forearm for defect coverage and shoulder contour reconstruction. Moreover, we performed TMR. Follow-up showed a satisfactory result and no phantom limb pain. In case of the need for free flap reconstruction after FQA, this review demonstrates the safety and advantage of osteomusculocutaneous fillet flaps. If the inclusion of the elbow joint into the flap is not possible, we recommend the use of the forearm, as described. Additionally, we advocate for the additional implementation of TMR, as it can be performed quickly and is likely to reduce phantom limb and neuroma pain.

Targeted Muscle Reinnervation in the Hand: A Technical Roadmap

PURPOSE

Targeted muscle reinnervation (TMR) transfers cut the nerve endings to the motor nerves of the nearby muscles to reduce neuroma pain and/or enhance prosthetic function. To guide surgeons, anatomic "roadmaps" describe nerve transfer options for TMR at various locations. This study aimed to landmark and measure motor entry points (MEPs) to the hand interossei muscles in the context of TMR for digital nerve neuroma management.

METHODS

Ten fresh-frozen cadaveric hands were dissected to describe the innervation arising from the deep branch of the ulnar nerve to the dorsal interossei (DIs) and palmar interossei (PIs) muscles. The location of MEPs relative to the bone and soft tissue landmarks and the size of the target nerves were measured.

RESULTS

The MEPs for the DIs and PIs were found in the central third of the metacarpal. The MEPs to the PIs averaged 23.3-24.7 mm from the median nerve. The length of nerve proximal to the MEP was limited, ranging between 6.5 ± 2.6 mm for the first PI and 10.5 ± 2.7 mm for the second PI. Similarly, minimal nerve proximal to the MEP of the DI was available for mobilization. Access to the first PI innervation required substantial release of the thenar musculature. Motor nerve diameter averaged 0.85-0.97 mm.

CONCLUSIONS

In considering TMR for the management or prevention of digital nerve neuromas, the motor branches to the second and third PIs are the most accessible and best approached volarly, whereas motor branches to the DIs take more direct routes into the muscle, making volar exposure difficult. Nerve length proximal to the MEP is short, requiring that most of the nerve length for neurorrhaphy comes from the digital nerve. Size mismatch at the neurorrhaphy site is favorable compared to more proximal TMR.

CLINICAL RELEVANCE

Targeted muscle reinnervation in the hand is technically feasible for a patient with a symptomatic neuroma after digital amputation.

Utilization of Techniques for Upper Extremity Amputation Neuroma Treatment and Prevention

This study aimed to understand the current utilization of surgical approaches for nerve ending management in upper extremity amputation to prevent and treat nerve-related pain. We administered a survey to 190 of 1270 surgeons contacted by email (15% response rate) and analyzed their demographics, practice patterns, and perceptions regarding techniques for nerve ending management in upper extremity amputees. Although many surgical techniques were employed, most surgeons (54%) performed traction neurectomy during amputation and, alternatively, bury nerve into muscle if a neuroma subsequently develops (52%). Surgeons in practice less than 10 years were more likely to perform targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNI) than surgeons in practice greater than 10 years (p<0.001). TMR and RPNI were performed more frequently for proximal amputations than distal amputations, but there is no consensus regarding the optimal timing to utilize these techniques. Surgeons commonly cited improved prosthetic control, pain, and phantom limb symptoms as reasons for performing TMR and RPNI. Increased physician compensation as a consideration was more commonly cited among TMR non-adopter than adopters (31% vs 14%, p=0.008). There is no consensus regarding techniques for the prevention or treatment of nerve ending pain in upper extremity amputees. TMR and RPNI are being utilized with increasing frequency and both patient and surgeon factors affect implementation in clinical practice.

Revision Peripheral Nerve Surgery of the Upper Extremity

Peripheral nerve injuries of the upper extremity can result from a wide array of etiologies, with the two most common being compression neuropathy and traumatic injuries. These types of injuries are common and can be psychologically, functionally, and financially devastating to the patient. A detailed preoperative evaluation is imperative for appropriate management. Traumatic injuries can typically be treated with local burial techniques, targeted muscle reinnervation, and regenerative peripheral nerve interfaces. Median nerve compression is frequently managed with complete release of the antebrachial fascia/transverse carpal ligament and/or use of flap coverage such as the hypothenar fat pad flap and local muscle flaps. Ulnar nerve compression is commonly managed via submuscular transposition, subcutaneous transposition, neurolysis, and nerve wrapping. In this review, we discuss the preoperative evaluation, surgical techniques, and advantages and disadvantages of each treatment modality for patients with compressive and traumatic upper extremity nerve injuries.

Targeted Muscle Reinnervation: A Paradigm Shift for Neuroma Management and Improved Prosthesis Control in Major Limb Amputees

Targeted muscle reinnervation (TMR) is a procedure that redirects nerves severed by amputation to new muscle targets. In tandem with advances in myoelectric prosthetics, TMR surgery provides amputees with improved control of myoelectric prostheses and simultaneously prevents or treats painful neuromas. TMR also has an emerging role in the management of neuromas in a nonamputation setting, and it seems to be a powerful strategy to treat a wide variety of neuromas. Because the pattern of nerve transfers varies based on the availability of donor nerves and muscle targets, TMR is inherently nonprescriptive, and thus, an understanding of the principles of TMR is essential for its successful application. This review describes the rationale for and principles of TMR, and outlines techniques for TMR, which can be used at various amputation levels and for the management of neuromas in nonamputees.

Targeted Muscle Reinnervation in the Hand: An Anatomical Feasibility Study for Neuroma Treatment and Prevention

PURPOSE

Targeted muscle reinnervation (TMR) has emerged as a treatment for, and prevention of, symptomatic neuromas and has been reported to be of benefit in the hand. Anatomical studies establishing landmarks for consistent identification of the motor entry points (MEPs) to the intrinsic muscles have not been performed. The purpose of this study was to provide details regarding the MEPs to the intrinsic muscles, determine which MEPs are identifiable dorsally, and develop recommended sensory to MEP nerve coaptations for prophylactic TMR at the time of ray amputation or for management of symptomatic neuromas.

METHODS

Motor entry points to the intrinsic hand muscles were dissected in 5 fresh latex-injected cadavers. Number of MEPs, diameter, surface of entry, and distance from dorsal (Lister tubercle) and volar (hamate hook) landmarks were recorded for each target muscle. The digital sensory nerve diameters were measured for size comparison.

RESULTS

Motor entry points were identified to all 19 intrinsic muscles through a volar approach and 12 through a dorsal approach. For all fingers, at least 2 MEPs were consistently identified dorsally at the base of each amputation site innervating expendable muscles. Motor entry points to the thenar muscles were only reliably identified through a volar approach. Two recommended nerve coaptations for each digit amputation were identified. All had a favorable sensory-to-MEP diameter ratio less than 2:1.

CONCLUSIONS

The intrinsic hand muscles have MEPs at consistent distances from bony landmarks both dorsally and volarly.

CLINICAL RELEVANCE

These results can be applied clinically to assist surgeons in identifying the locations of MEPs to the intrinsic muscles when performing TMR in the hand for both neuroma treatment and prevention.