Targeted muscle reinnervation for the management of pain in the setting of major limb amputation

Social media analysis of pain outcomes following targeted muscle reinnervation

AIM

Targeted muscle reinnervation (TMR) was developed to improve myoelectric prosthesis control for amputees; however, it has become an area of interest in pain modulation. Evidences indicate that this procedure alleviates chronic pain in amputees. The primary objective of this study was to use social media analysis to understand patients' post-operative pain, satisfaction, and recovery time after TMR.

METHODS

Data were collected from one Facebook group via posts and comments referencing TMR. Posts published between January 1, 2020, and March 24, 2023 were analyzed. Data collected included pain prior to surgery, pain in immediate post-op period, and change in pain after surgery.

RESULTS

Forty-three individuals commented on their TMR experience. Among them, 31 had favorable surgical outcomes, 7 felt that the surgery worsened their pain or there was no significant change in their pain levels, and 5 commented during the initial post-operative period. Twenty-four patients described their pain in the immediate post-operative period and all patients said that the post-operative pain was worse than chronic pain. Among the 28 authors who commented on overall reduction in chronic pain, 24 reported that TMR reduced their pain, whereas 4 reported no change or worsened pain.

CONCLUSIONS

The number of patients (24) who reported improvement in chronic pain aligns with the results in current literature suggesting that TMR is a viable treatment option for pain management. With the current medical management of similar conditions, up to 80% of patients remain unsatisfied with pain management. This analysis supports the evidence that TMR is an effective treatment for patients experiencing post-amputation pain.

Similar rates of reoperation for neuroma after transtibial amputations with and without targeted muscle reinnervation

Objective

To compare the rates of revision surgery for symptomatic neuromas in patients undergoing primary transtibial amputations with and without targeted muscle reinnervation (TMR).

Design

Retrospective cohort study.

Setting

Level I trauma hospital and tertiary military medical center.

Patients/Participants

Adult patients undergoing transtibial amputations with and without TMR.

Intervention

Transtibial amputation with targeted muscle reinnervation.

Main Outcome Measurements

Reoperation for symptomatic neuroma.

Results

During the study period, there were 112 primary transtibial amputations performed, 29 with TMR and 83 without TMR. Over the same period, there were 51 revision transtibial amputations performed, including 23 (21%) in the patients undergoing primary transtibial amputation at the study institution. The most common indications for revision surgery were wound breakdown/dehiscence (42%, n = 25), followed by symptomatic neuroma 18% (n = 9/51) and infection/osteomyelitis (17%, n = 10) as the most common indications. However, of the patients undergoing primary amputation at the study's institution, there was no difference in reoperation rates for neuroma when comparing the TMR group (3.6%, n = 1/28) and no TMR group (4.0%, n = 3/75) (P = 0.97).

Conclusions

Symptomatic neuroma is one of the most common reasons for revision amputation; however, this study was unable to demonstrate a difference in revision surgery rates for neuroma for patients undergoing primary transtibial amputation with or without targeted muscle reinnervation.

Level of Evidence

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

TMR for Peripheral Sensory Nerve Neuroma around the Wrist Utilizing the Distal Anterior Interosseous Nerve

Injury to the peripheral sensory nerves of the hand and wrist is common and can lead to debilitating neuromas and significantly impair patients' quality of life. Target-muscle reinnervation (TMR) is a novel method for treating neuromas that can result in significant clinical improvement. However, TMR for the peripheral sensory nerves in the hand and wrist is restricted by the limited options for motor branches. The adaptability of the anterior interosseous nerve (AIN) as a target for TMR treating peripheral sensory neuroma has not been thoroughly investigated or implemented therapeutically. This study aimed to evaluate the use of AIN as a viable recipient of TMR for treating peripheral sensory neuromas around the wrist. In this retrospective study, eight patients were included over 18 months from June 2021 to January 2023 at Hamad Medical Corporation. The average follow-up time after TMR was 13 months. The peripheral sensory nerves involved were the radial sensory nerve in five cases, the palmar cutaneous branch of the median nerve in one case, and the median nerve in one case. The preoperative average VAS pain score was 7 of 10 compared with the postoperative pain score of 2 of 10. In conclusion, the AIN can be used as a first-choice motor target for all peripheral sensory neuromas around the wrist for the following reasons: first, it can be reached by the peripheral sensory nerves around the wrist; second, the pronator quadratus muscle is expandable; and third, the AIN can be taken with a long proximal tail for flexible coaptation with the peripheral sensory nerves.

A Direct Comparison of Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces to Prevent Neuroma Pain

BACKGROUND AND OBJECTIVES

Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) surgeries manage neuroma pain; however, there remains considerable discord regarding the best treatment strategy. We provide a direct comparison of TMR and RPNI surgery using a rodent model for the treatment of neuroma pain.

METHODS

The tibial nerve of 36 Fischer rats was transected and secured to the dermis to promote neuroma formation. Pain was assessed using mechanical stimulation at the neuroma site (direct pain) and von Frey analysis at the footpad (to assess tactile allodynia from collateral innervation). Once painful neuromas were detected 6 weeks later, animals were randomized to experimental groups: (a) TMR to the motor branch to biceps femoris, (b) RPNI with an extensor digitorum longus graft, (c) neuroma excision, and (d) neuroma in situ. The TMR/RPNIs were harvested to confirm muscle reinnervation, and the sensory ganglia and nerves were harvested to assess markers of regeneration, pain, and inflammation.

RESULTS

Ten weeks post-TMR/RPNI surgery, animals had decreased pain scores compared with controls ( P < .001) and they both demonstrated neuromuscular junction reinnervation. Compared with neuroma controls, immunohistochemistry showed that sensory neuronal cell bodies of TMR and RPNI showed a decrease in regeneration markers phosphorylated cyclic AMP receptor binding protein and activation transcription factor 3 and pain markers transient receptor potential vanilloid 1 and neuropeptide Y ( P < .05). The nerve and dorsal root ganglion maintained elevated Iba-1 expression in all cohorts.

CONCLUSION

RPNI and TMR improved pain scores after neuroma resection suggesting both may be clinically feasible techniques for improving outcomes for patients with nerve injuries or those undergoing amputation.

Targeted muscle reinnervation in upper extremity amputations

PURPOSE

Targeted muscle reinnervation (TMR) is a relatively recent surgical innovation that involves the coaptation of major peripheral nerves to a recipient motor branch that innervates an expendable muscle target. The original indication for TMR was augmentation and optimization of myoelectric signals in the amputated limb for use of myoelectric prosthetics. Incidentally, surgeons and patients discovered that the technique also could treat and prevent phantom and residual limb pain. TMR is performed at the time of amputation or delayed any time after the amputation, and TMR can also be performed at any level of amputation. In the upper extremity, studies have detailed the various techniques and coaptations possible at each amputation level to create intuitive myoelectric signals and treat neurogenic pain. Treatment of peripheral nerves in the amputee with TMR should be a consideration for all patients with major upper extremity amputations, especially at large institutions able to support multidisciplinary limb salvage teams. This review article summarizes the current literature and authors' techniques and recommendations surrounding TMR in the upper extremity amputee including techniques relevant to each level of upper extremity amputation.

Targeted muscle reinnervation in upper extremity amputation in military hand surgery: A systematic review

INTRODUCTION

Targeted Muscle Reinnervation (TMR) is a surgical technique utilized to alleviate post-amputation neuroma pain, reduce reliance on narcotic pain medication, and enhance control of prosthetic devices. Motor targets for upper extremity TMR vary depending on injury patterns and amputation levels, with conventional transfer patterns serving as general guides. This study aims to summarize the common patterns of TMR in transradial and transhumeral amputations, focusing on anatomic and surgical considerations.

METHODS

A comprehensive systematic review of TMR literature was conducted by two independent physician reviewers (M.H.A. and D.M.G.R.) to identify the prevailing motor targets, while considering injury patterns and amputation levels.

INCLUSION CRITERIA

1) TMR techniques, outcomes, or advancements; 2) Original research, systematic reviews, meta-analyses, or clinical trials; 3) Peer-reviewed journal articles or reputable conference proceedings.

EXCLUSION CRITERIA

non-English resources, editorials, opinion pieces, and case reports. The databases utilized include MEDLINE (PubMed), EMBASE (Scopus) and Cochrane CENTRAL, last searched 01APR2023.

RESULTS

The reviewed literature revealed multiple motor targets described for upper extremity TMR out of our included 51 studies. However, the selection of motor targets is influenced by the availability of viable options based on injury patterns and amputation levels. Conventional transfer patterns provide useful guidance for determining appropriate motor targets in transradial and transhumeral amputations.

DISCUSSION

TMR has played a significant role in military medicine, particularly in addressing the impact of blast-related injuries. The energy associated with such injuries often results in substantial soft tissue defects, higher amputation levels, and increased post-amputation pain. TMR, in conjunction with advancements in prosthetic technology and ongoing military research, offers improved outcomes to help achieve the goals of active-duty service members. The capabilities and applications of TMR continue to expand rapidly due to its high surgical success rate, technological innovations in prosthetic care, and favorable patient outcomes. As technology evolves to include implantable devices, osseointegration techniques, and bidirectional neuroprosthetic devices, the future of amputation surgery and TMR holds immense promise, offering innovative solutions to optimize patient outcomes. It is important to note, this review was limited to the data available in the included resources which was mostly qualitative; thus, it did not involve primary data analysis.

Forequarter Amputation: Reconstruction With Targeted Muscle Reinnervation to the Filet of Forearm Free Flap

Forequarter amputation is a rarely indicated operation that has the potential for delayed wound healing, chronic pain, and dysfunction. Reconstruction in cases of skin and soft tissue loss may be particularly challenging. Here we present a 79-year-old female with recurrent, previously radiated left shoulder chondrosarcoma who underwent forequarter amputation with a 'spare parts' filet of forearm flap and targeted muscle reinnervation to the flap. The patient healed without complication and achieved reinnervation with minimal pain.

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

Targeted muscle reinnervation (TMR) outcome studies reveal the benefit amputees experience and the potential functional improvement by optimizing neurocutaneous signaling for myoelectric prosthesis control. However, there are still many settings where these techniques are not offered to patients requiring lower extremity amputations or neuroma reconstruction. With growing consistency in the literature, it is helpful to systematize the nerve transfers described for lower extremity TMR and to simplify its integration into reconstructive care.

Methods

A systematic literature review was performed and contained the following inclusion criteria: original cases of primary or secondary lower extremity amputation defects or nerve-related pain that underwent TMR with clearly described target muscles for each nerve transfer. Studies were excluded if the cases had been previously described or contained incomplete data. The primary outcomes were nerves transferred and muscles targeted. Target muscle options were presented in tables specific to anatomic region, and cross-sectional schematics were created for intraoperative assistance.

Results

Seventeen studies presenting original cases with clearly described nerve transfers and target muscles in the lower extremity were included in the review. Target muscle selection for all nerve transfers at the transfemoral and transtibial levels were presented in separate tables.

Conclusions

Reports of early experience at multiple institutions identify trends in the selection of certain target muscles for nerve transfers in transfemoral and transtibial TMR. Familiarity with these common target muscles and nerve transfers can simplify intraoperative decision-making and enhance integration of lower extremity TMR in amputation care and in the treatment of nerve-related pain.

Targeted Muscle Reinnervation in the Setting of Traumatic Bilateral Above-Knee Amputations: A Case Report

CASE

We present the case of a 20-year-old man who was pedestrian struck and sustained bilateral traumatic above-knee amputations. Targeted muscle reinnervation (TMR) was performed with nerve transfers, including tibial nerve to semitendinosus (bilateral), superficial peroneal nerve to biceps femoris (left), deep peroneal nerve to biceps femoris (left), and common peroneal nerve to biceps femoris (right).

CONCLUSIONS

Less than 1 year postoperatively, the patient was ambulating on his myoelectric prosthesis and experienced no Tinel or neuroma-type pain. This case is a testament to the impact TMR, an innovative surgical technique, can have on the quality of life of patients sustaining devastating limb injuries.

Osseointegration for Lower-Extremity Amputees: Operative Considerations from the Plastic Surgeon's Perspective

➢

Osseointegration for lower-extremity amputees, while increasing in frequency, remains in its relative infancy compared with traditional socket-based prostheses.

➢

Ideal candidates for osseointegration have documented failure of a traditional prosthesis and should be skeletally mature, have adequate bone stock, demonstrate an ability to adhere to a longitudinal rehabilitation protocol, and be in an otherwise good state of health.

➢

Lowering the reoperation rate for soft-tissue complications depends heavily on surgical technique and on the implant device itself; the current gold standard involves a smooth implant surface for dermal contact as well as maximal skin resection to prevent skin breakdown against the prosthesis. This may include the need for thighplasty to optimize skin reduction.

➢

Interdisciplinary peripheral nerve management, such as targeted muscle reinnervation, performed in tandem with a plastic surgery team can treat existing and prevent future symptomatic neuromas, ultimately improving pain outcomes.

An Algorithm Approach to Phantom Limb Pain

Phantom limb pain (PLP) is a common condition that occurs following both upper and lower limb amputation. First recognized and described in 1551 by Ambroise Pare, research into its underlying pathology and effective treatments remains a very active and growing field. To date, however, there is little consensus regarding the optimal management of phantom limb pain. With few large well-designed clinical trials of which to make treatment recommendations, as well as significant heterogeneity in clinical response to available treatments, the management of PLP remains challenging. Below we summarize the current state of knowledge in the field, as well as propose an algorithm for the approach to the treatment of PLP.

Nerve Decompression and Distal Transtibial Amputation

Approximately 20% of patients with diabetic peripheral neuropathy (DPN) endorse painful sensations such as prickling, stabbing, and burning pain that reflect small-fiber involvement. Although glycemic control is crucial to delay the onset and progression of DPN, there have been many reports on the use of decompression nerve surgery to aid in the treatment of DPN.

Free Vascularized Fibular Flap with Bilateral Bipolar Latissimus Transfer for Upper Extremity Reconstruction: A Case Report

CASE

A 19-year-old woman presented with bilateral mangled upper extremities after jumping in front of a moving train. After revascularization, osteocutaneous free vascularized fibula flap was performed to reconstruct the right humerus. The left forearm required transradial amputation with acute targeted muscle reinnervation. Finally, staged bilateral bipolar latissimus dorsi functional muscle flaps were performed to restore elbow flexion.

CONCLUSION

Staged orthoplastic reconstruction of the upper extremities is an effective treatment approach for traumatic bone and soft-tissue defects. This patient's recovery demonstrates improved quality of life after severe upper extremity trauma.

Peripheral Nerve Management in Extremity Amputations

The effective management of peripheral nerves in amputation surgery is critical to optimizing patient outcomes. Nerve-related pain after amputation is common, maybe a source of dissatisfaction and functional impairment, and should be considered in all amputees presenting with pain and dysfunction. While traction neurectomy or transposition has long been the standard of care, both regenerative peripheral nerve interface (RPNI) and targeted muscle reinnervation (TMR) have emerged as promising techniques to improve neuroma-related and phantom pain. A multi-disciplinary and multi-modal approach is essential for the optimal management of amputees both acutely and in the delayed or chronic setting.

Pericyte‑derived extracellular vesicles‑mimetic nanovesicles improves peripheral nerve regeneration in mouse models of sciatic nerve transection

Pericyte‑derived extracellular vesicle‑mimetic nanovesicles (PC‑NVs) play an important role in the improvement of erectile function after cavernous nerve injury. However, the impact of PC‑NVs on the peripheral nervous system (PNS), such as the sciatic nerve, is unclear. In this study, PC‑NVs were isolated from mouse cavernous pericytes (MCPs). A sciatic nerve transection (SNT) model was established using 8‑week‑old C57BL/6J mice. The sciatic nerve was harvested 5 and 14 days for immunofluorescence and western blot studies. Function studies were evaluated by performing the rotarod test and walking track analysis. The results demonstrated that PC‑NVs could stimulate endothelial cells, increase neuronal cell content, and increase macrophage and Schwann cell presence at the proximal stump rather than the distal stump in the SNT model, thereby improving angiogenesis and nerve regeneration in the early stage of sciatic nerve regeneration. In addition, PC‑NVs also increased the expression of neurotrophic factors (brain‑derived nerve growth factor, neurotrophin‑3 and nerve growth factor) and the activity of the cell survival signaling pathway (PI3K/Akt signaling), and reduced the activity of the JNK signaling pathway. Additionally, after 8 weeks of local application of PC‑NVs in SNT model mice, their motor and sensory functions were significantly improved, as assessed by performing the rotarod test and walking track analysis. In conclusion, the present study showed that the significant improvement of neurovascular regeneration in mice following treatment with PC‑NVs may provide a favorable strategy for promoting motor and sensory regeneration and functional recovery of the PNS.

Challenges and Potential in Targeted Muscle Reinnervation in Pediatric Amputees

Targeted muscle reinnervation (TMR) is a powerful new tool in preventing and treating residual limb and phantom limb pain. In the adult population, TMR is rapidly becoming standard of care; however, there is a paucity of literature regarding indications and outcomes of TMR in the pediatric population. We present 2 cases of pediatric patients who sustained amputations and the relevant challenges associated with TMR in their cases. One is a 7-year-old patient who developed severe phantom and residual limb pain after a posttraumatic above-knee amputation. He failed pharmacologic measures and underwent TMR. He obtained complete relief of his symptoms and is continuing to do well 1.5 years postoperatively. The other is a 2-year-old boy with bilateral wrist and below-knee amputations as sequelae of sepsis. TMR was not performed because the patient never demonstrated evidence of phantom limb pain or symptomatic neuroma formation. We use these 2 cases to explore the challenges particular to pediatric patients when considering treatment with TMR, including capacity to report pain, risks of anesthesia, and cortical plasticity. These issues will be critical in determining how TMR will be applied to pediatric patients.

Stump-plasty: An Operation Born of Necessity in Gaza

Aim and objective

The most recent wave of lower limb amputees in Gaza arises from ballistic injuries sustained during protests. This study evaluates the requirement for surgical revision of these mature stumps to allow prosthetic fit and mobility.

Materials and methods

A multidisciplinary team (MDT) comprising a prosthetist, orthopaedic and plastic surgeons and a physiotherapist screened 104 amputee stumps (103 cases). The 27 cases selected for surgical revision (stump-plasty) are the subject of this study.

The MDT prescriptions of care issued at screening were compared to surgical procedures performed at stump-plasty and the findings. Compliance with the MDT prescription was recorded. Stump issues are identified to propose modifications of primary amputation technique to mitigate future revisions.

Patients’ healthcare status was assessed by questionnaire (EQ-5D-L5) at screening, then subsequently post-stump-plasty.

Results

More below-knee amputees (BKAs) than above-knee amputees (AKAs) required stump-plasty. Revisions varied according to the quality of tissue present at the amputation level. AKA revisions addressed bulk and contour issues whereas BKA revisions related to bone prominence, neuroma formation and lack of soft tissue cover. Despite many variations in tissue-targeted procedures being possible, the MDT prescription was followed accurately at surgery.

Suggested modifications at primary amputation to decrease revisions include improved bone tip bevelling at BKA and greater soft tissue reduction at AKA. Severed nerve management needs to be rationalised to reduce primary neuroma formation and neuroma revision at stump-plasty requires consideration to attempt to reduce the recurrent risk. Removal of the fibular remnant in short BKA stumps at primary amputation could mitigate common peroneal nerve hypersensitivity later.

Following stump-plasty, amputees recorded a significantly improved score in three of five dimensions of the EQ-5D-L5 questionnaire: activities, anxiety levels and pain.

Conclusion and clinical significance

Primary ballistic injury dictates the level of amputation and the resultant stump quality. Issues arising in these complex amputee stumps benefited from measured decisions and specialist care delivered by the MDT. Stump-plasty aims to improve the amputees’ prosthetic fit, mobility and health.

How to cite this article

Godwin Y, Almaqadma A, Abukhoussa H, et al. Stump-plasty: An Operation Born of Necessity in Gaza. Strategies Trauma Limb Reconstr 2021;16(2):102–109.

The Need to Work Arm in Arm: Calling for Collaboration in Delivering Neuroprosthetic Limb Replacements

Over the last few decades there has been a push to enhance the use of advanced prosthetics within the fields of biomedical engineering, neuroscience, and surgery. Through the development of peripheral neural interfaces and invasive electrodes, an individual's own nervous system can be used to control a prosthesis. With novel improvements in neural recording and signal decoding, this intimate communication has paved the way for bidirectional and intuitive control of prostheses. While various collaborations between engineers and surgeons have led to considerable success with motor control and pain management, it has been significantly more challenging to restore sensation. Many of the existing peripheral neural interfaces have demonstrated success in one of these modalities; however, none are currently able to fully restore limb function. Though this is in part due to the complexity of the human somatosensory system and stability of bioelectronics, the fragmentary and as-yet uncoordinated nature of the neuroprosthetic industry further complicates this advancement. In this review, we provide a comprehensive overview of the current field of neuroprosthetics and explore potential strategies to address its unique challenges. These include exploration of electrodes, surgical techniques, control methods, and prosthetic technology. Additionally, we propose a new approach to optimizing prosthetic limb function and facilitating clinical application by capitalizing on available resources. It is incumbent upon academia and industry to encourage collaboration and utilization of different peripheral neural interfaces in combination with each other to create versatile limbs that not only improve function but quality of life. Despite the rapidly evolving technology, if the field continues to work in divided "silos," we will delay achieving the critical, valuable outcome: creating a prosthetic limb that is right for the patient and positively affects their life.