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.

Adipose-derived stem cell to epithelial stem cell transdifferentiation: a mechanism to potentially improve understanding of fat grafting's impact on skin rejuvenation.

BACKGROUND: Recent evidence suggests that lipofilling improves overlying skin composition and appearance. Adipose-derived stem cells (ADSC) have been implicated. OBJECTIVE: The authors identify ADSC transdifferentiation into epithelial stem cells through coexpression of GFP+ (green fluorescent protein positive) ADSC with the epithelial stem cell marker p63 in an in vivo fat grafting model. METHODS: Six male, GFP+ mice served as adipose tissue donors. Twelve nude mice served as recipients. Recipients were subdivided into 2 arms (6 mice/each arm) and received either whole-fat specimen (group 1) or isolated and purified ADSC + peptide hydrogel carrier (group 2) engrafted into a 1-cm(2) left parascapular subdermal plane. The right parascapular subdermal plane served as control. Skin flaps were harvested at 8 weeks and subjected to (1) confocal fluorescent microscopy and (2) reverse transcriptase polymerase chain reaction (RT-PCR) for p63 mRNA expression levels. RESULTS: Gross examination of skin flaps demonstrated subjectively increased dermal vessel presence surrounding whole-fat and ADSC specimens. The GFP+ cells were seen within overlying dermal architecture after engraftment and were found to coexpress p63. Significantly increased levels of p63 expression were found in the ADSC + hydrogel skin flaps. CONCLUSIONS: We offer suggestive evidence that GFP+ ADSC are found within the dermis 8 weeks after engraftment and coexpress the epithelial stem cell marker p63, indicating that ADSC may transdifferentiate into epithelial stem cells after fat grafting. These findings complement current understanding of how fat grafts may rejuvenate overlying skin.

Targeted muscle reinnervation of a muscle-free flap for improved prosthetic control in a shoulder amputee: case report.

We report a case of targeted muscle reinnervation of a muscle free flap for improved prosthetic control in a patient who had an amputation of the left upper extremity at the level of the shoulder after a severe electrical burn. The reinnervated muscle free flap receives signals from the brachial plexus, and these signals are amplified to provide an interface for a myoelectric prosthesis. This allows for more coordinated and efficient control of the artificial limb.

Stimulating angiogenesis by hyperbaric oxygen in an isolated tissue construct.

BACKGROUND: Hyperbaric oxygen (HBO2) treatment has been shown to stimulate angiogenesis in prefabricated myocutaneous flaps. We conducted the current study to determine optimal HBO2 treatment intervals for peak angiogenesis. METHODS: Lewis rats were implanted subcutaneously with silicone molds in the inguinal region. Molds contained inguinal fat, a vascular pedicle and Matrigel plug. Thirty-two animals were randomized into four groups: HBO2 Treatment (2.5 atm of 100% oxygen, 90 minutes, 2x/day)--Group 1 (seven days) or--Group 2 (14 days); and Control Treatment (room air at atmospheric pressure)--Group 1 (seven days) or--Group 2(14 days). Implants were harvested, processed for H&E staining, and imaged digitally; angiogenesis was assessed by grade of vascularization at the Matrigel/fat boundary. Intergroup grading differences were assessed statistically. RESULTS: Vascularization in seven-day HBO2-treated implants was significantly increased compared to seven-day controls (p = 0.008). Vascularization in 14-day HBO2-treated implants was significantly decreased compared to 14-day controls (p = 0.012). There was no significant difference between seven-day HBO-treated implants and 14-day controls (p > 0.05). CONCLUSIONS: Short-term HBO2 exposure appears to increase angiogenesis in isolated tissue constructs. Prolonged HBO2 exposure may lead to vascular pruning. Short-term HBO2 exposure appears to expedite the natural vascularization process, resulting in equivalent vascularization in a shorter time.

Surgical Technique for Below-knee Amputation with Concurrent Targeted Muscle Reinnervation.

Targeted muscle reinnervation (TMR) is beneficial for decreasing pain following below-knee amputation (BKA). While most current literature describes the principles behind primary TMR, they provide few principles key to the amputation, as the BKA is usually performed by another surgeon. When the BKA and TMR are performed by the same surgeon, it can be performed through the same surgical access as needed for both procedures. The purpose of this article is to describe our anatomically based BKA technique in the setting of planned primary TMR as performed by 3, single, peripheral nerve plastic surgeons at 2 institutions. Advantages of the single-surgeon technique include efficiency in dissection, preservation of donor nerve length, limited proximal dissection, early identification of recipient motor nerves for coaptation, ability to stimulate these while still under tourniquet, and decreased tourniquet and operative time. This technique is quick, reliable, and reproducible to help promote widespread adoption of TMR at the time of BKA.

Novel Use of Targeted Muscle Reinnervation in the Hand for Treatment of Recurrent Symptomatic Neuromas Following Digit Amputations.

Targeted muscle reinnervation (TMR) has been shown to decrease neuroma pain after major limb loss; however, it has not previously been described for the treatment of symptomatic neuromas in the hand after digit amputations. This report describes the use of TMR in the hand for treatment of a patient with recurrent neuromas after ray amputation of the index and long fingers that were refractory to traditional treatments. TMR was performed first for the superficial branch of the radial nerve 6 years ago to treat the dorsal neuroma pain. Following this, there was complete resolution on the dorsal aspect of the hand, however, continued neuroma pain on the volar aspect of the hand. This was treated more recently with excision of the neuromas and TMR to motor branches of the intrinsic muscles of the hand. Outcomes were measured with a numerical rating scale and Patient-Reported Outcomes Measurement System assessments and revealed decreased pain postoperatively and less interference of her activities due to pain. This report demonstrates the ability to perform TMR within the hand with good results when used for the treatment of symptomatic neuromas.

Ring Avulsion Injuries: A Systematic Review.

BACKGROUND: Ring avulsion injuries can range from soft tissue injury to complete amputation. Grading systems have been developed to guide treatment, but there is controversy with high-grade injuries. Traditionally, advanced ring injuries have been treated with completion amputation, but there is evidence that severe ring injuries can be salvaged. The purpose of this systematic review was to pool the current published data on ring injuries. METHODS: A systematic review of the English literature published from 1980 to 2015 in PubMed and MEDLINE databases was conducted to identify patients who underwent treatment for ring avulsion injuries. RESULTS: Twenty studies of ring avulsion injuries met the inclusion criteria. There were a total of 572 patients reported with ring avulsion injuries. The Urbaniak class breakdown was class I (54 patients), class II (204 patients), and class III (314 patients). The average total arc of motion (TAM) for patients with a class I injury was 201.25 (n = 40). The average 2-point discrimination was 5.6 (n = 10). The average TAM for patients with a class II injury undergoing microsurgical revascularization was 187.0 (n = 114), and the average 2-point discrimination was 8.3 (n = 40). The average TAM for patients with a class III injury undergoing microsurgical revascularization was 168.2 (n = 170), and the average 2-point discrimination was 10.5 (n = 97). CONCLUSIONS: Ring avulsion injuries are commonly classified with the Urbaniak class system. Outcomes are superior for class I and II injuries, and there are select class III injuries that can be treated with replantation. Shared decision making with patients is imperative to determine whether replantation is appropriate.

Replantation outcomes.

Replantation aims to restore the amputated part to its anatomical site, preserving function and appearance. Outcome depends on factors intrinsic to the patient and to the nature of the injury. Young patients who have distal, cleanly amputated extremities have the best return of function; multiple levels of injury, crush, or avulsing injuries have less. Patients must be fully informed about the commitment to rehabilitation and the possibility of multiple surgeries needed for best results. Similarly, patient and surgeon expectations should be evaluated and addressed before replantation. Meticulous microsurgical technique, comprehensive occupational therapy, and perseverance are needed for success. Addressing these issues promotes a team rehabilitation to restore function while getting the amputation patient back to productive position in society.

Microsurgical Reconstruction of the Burned Hand and Upper Extremity.

Improvements in critical care and burn victim resuscitation have led to increased survival of burned patients. Initial resuscitation, early excision of burned tissues, prevention of burn wound sepsis, and wound coverage remain mainstays of care. Many burn wounds require complex reconstruction. This is particularly important in the hand. Coverage of tendons, ligaments, joints, vessels, nerves, and bones of the hand requires healthy vascularized tissue to maintain viability and function. Local flaps or regional flaps may be within the burn zone of injury. Refined microvascular free tissue transfer techniques offer free tissue transfer as a procedure that can be safely performed.

Outcomes after mutilating hand injuries: review of the literature and recommendations for assessment.

The functional outcome of a mutilating hand injury cannot be fully assessed at the time of injury alone. The measure of functional outcome must incorporate the evaluation and severity of the initial injury and the subsequent reconstructive surgeries. The complexity of the hand deserves no less. Restoration of prehensile function is the top priority in reconstruction following mutilating hand injuries, and assessment of outcome should address this goal. Flaps and specialized tissue grafts can restore architecture and balance in the hand. One can reconstruct a thumb and fingers with the big toe and smaller toes to give a functional sensate grip. The assessment of functional outcome should include not only objective measures but also subjective questionnaires that focus on issues most relevant to the patient. The use of questionnaires that have been shown to be valid, reliable, consistent, responsive, and sensitive allows the most meaningful conclusions about and comparisons between treatments. Perhaps because of the unique challenges presented by mutilating hand injuries, a new instrument, specific to mutilating hand injury, may provide the most beneficial information to guide treatment and assess outcome.

Secondary procedures following mutilating hand injuries.

Mutilating hand injuries result in injury to multiple anatomic structures, which increases the possibility that secondary procedures or staged reconstruction will be necessary. Secondary procedures often are required to provide stable wound coverage, restore sensation, provide bony stability, increase range of motion, or allow prehension, all of which are performed to improve hand function. The patient, the surgeon, and the therapist must all work together to achieve the best functional result following a severe mutilating hand injury.

Hand tumors: II. Benign and malignant bone tumors of the hand.

The incidence of both benign and malignant bone tumors arising in the hand is relatively low in comparison with other locations. Although the overwhelming majority of these tumors are benign, even benign tumors can be locally destructive and compromise hand function. Intralesional tumor excision is the most appropriate surgical intervention for many benign bone tumors of the hand; however, destructive or malignant tumors may require wide local excision or even amputation to achieve complete tumor eradication. The purpose of this review article is to provide an overview of the pertinent benign and malignant bone tumors that may be encountered by hand surgeons. Clinical presentation, radiographic features, recommended workup, and available treatment options are all reviewed.

Integra® dermal regenerative template application on exposed tendon.

BACKGROUND: Tendon without paratenon presents the reconstructive surgeon with a tissue coverage challenge. Integra® dermal regenerative template has been shown to initiate a stable, vascularized bed for skin grafting over tendon. However, histological processes that occur during incorporation have not been described. The purpose of this study is to characterize the pattern of changes that occur when Integra® is applied to an avascular tendon. We hypothesize that vascular incorporation will originate from the wound periphery and proceed toward the tendon center. METHODS: A full-thickness defect was created over a denuded Achilles tendon in a single hind limb in eight New Zealand white rabbits. Integra was placed over the avascular tendon, and the limb was dressed and splinted. Two animals were euthanized at each timepoint (weeks 1, 2, 3, and 4), and hematoxylin and eosin (H&E)-stained tissue specimens were microscopically evaluated. RESULTS: Week 1 specimens demonstrated limited adherence between Integra and the tendon, while myofibroblasts were found encircling the tendon. No cellularity was noted centrally. At week 2, the dermis-Integra junction had increasing vascularity and the central portion developed increasing cellularity. By week 3, Integra was completely revascularized. At week 4, Integra had the histological appearance of normal dermis. CONCLUSION: Neovascularization of Integra® over exposed tendon occurs from the peripheral tissue. Ingrowth proceeds from the dermis-Integra interface toward the center of the graft. Four weeks after application to the denuded tendon, Integra has the histological appearance of native dermis.

Hand tumors: I. skin and soft-tissue tumors of the hand.

SUMMARY: Hand tumors of the skin and soft tissue are frequently encountered by plastic surgeons. Although similar to lesions affecting other parts of the body, the presentation, workup, and treatment options often differ in the hand secondary to its complex anatomy and functional significance. The purpose of this article is to provide an overview of those lesions that commonly arise in the hand-including epidermal inclusion cysts, ganglion cysts, and glomus tumors-in addition to tumors such as soft-tissue sarcomas that are rare but nonetheless require astute diagnosis and expedient initiation of treatment. Presenting symptoms and clinical features, recommended workup, and appropriate treatment options are reviewed.

Replantation: current concepts and outcomes.

Techniques to improve the chance of successful replantation of digits are well established. Indications and contraindications for replantation are generally agreed on, but they continue to evolve as excellent outcomes are achieved at centers with experience and expertise. Form and function can be restored with avulsion injuries and distal amputations, with good results and high patient satisfaction. Increased financial pressure to control the costs of health care and increased accountability for evidence-based outcomes may lead to the regionalization of replantation care and shared decision making in recommending replantation or revision amputation.

Subungual melanoma: a review of current treatment.

BACKGROUND: Subungual melanoma typically presents as a darkened longitudinal stripe under the nail plate; however, this disease is frequently misdiagnosed, which leads to a delay in proper diagnosis. Subsequently, subungual melanoma historically has a relatively poor prognosis compared with other cutaneous melanomas, with the 5-year survival rate ranging between 16 and 80 percent. Historically, these lesions were removed using aggressive amputation. To date, the National Cancer Institute does not have guidelines for the treatment of subungual melanoma. METHODS: The authors conducted a complete review of all cases within the literature involving amputation and/or wide local excision for the treatment of subungual melanoma. RESULTS: There is currently a trend toward a more conservative approach in treating subungual melanoma; however, the literature does not offer a high level of evidence, and definitive conclusions cannot be drawn. CONCLUSIONS: Overall, the studies within the literature involving amputation as the treatment for subungual melanoma could not prove a significant benefit, in terms of prognosis and/or survival, over the more conservative treatment of excision. The collective data imply that melanoma in situ can likely be treated appropriately with wide local excision. The literature lacks randomized, prospective, or comparative studies that would help elucidate whether amputation is superior to a more conservative, digit-sparing approach. Prospective randomized control trials are indicated.

Targeted muscle reinnervation in the initial management of traumatic upper extremity amputation injury.

Targeted muscle reinnervation (TMR) was initially designed to provide cortical control of upper limb prostheses through a series of novel nerve transfers. Early experience has suggested that TMR may also inhibit symptomatic neuroma formation. We present the first report of TMR performed at the time of a traumatic shoulder disarticulation. The procedure was done to prevent painful neuroma pain and allow for myoelecteric prosthetic use in the future. Eight months post-operatively, the patient demonstrates multiple successful nerve transfers and exhibits no evidence of neuroma pain on clinical exam. Using the Patient Reported Outcomes Measurement Information System (PROMIS), the patient demonstrates minimal pain interference or pain behavior. Targeted muscle reinnervation may be considered in the acute trauma setting to prevent neuroma pain and to prepare patients for myoelectric prostheses in the future.

Vascularized bone grafts for the treatment of carpal bone pathology.

Primary bone healing fails to occur in 5-15 % of scaphoid bones that undergo fracture fixation. Untreated, occult fractures result in nonunion up to 12 % of the time. Conventional bone grafting is the accepted management in the treatment algorithm of scaphoid nonunion if the proximal pole is vascularized. Osteonecrosis of the proximal scaphoid pole intuitively suggests a need for transfer of the vascularized bone to the nonunion site. Scaphoid nonunion treatment aims to prevent biological and mechanical subsidence of the involved bone, destabilization of the carpus, and early degenerative changes associated with scaphoid nonunion advanced collapse. Pedicled distal radius and free vascularized bone grafts (VBGs) offer hand surgeons an alternative treatment option in the management of carpal bone nonunion. VBGs are also indicated in the treatment of avascular necrosis of the scaphoid (Preiser's disease), lunate (Kienböck's disease), and capitate. Relative contraindications to pedicled dorsal radius vascularized bone grafting include humpback deformity, carpal instability, or collapse. The free medial femoral condyle bone graft has offered a novel treatment option for the humpback deformity to restore geometry of the carpus, otherwise not provided by pedicled grafts. In general, VBGs are contraindicated in the setting of a carpal bone without an intact cartilaginous shell, in advanced carpal collapse with degenerative changes, and in attempts to salvage small or collapsed bone fragments. Wrist salvage procedures are generally accepted as the more definitive treatment option under such circumstances. This manuscript offers a current review of the techniques and outcomes of VBGs to the carpal bones.

Innovations in prosthetic interfaces for the upper extremity.

Advancements in modern robotic technology have led to the development of highly sophisticated upper extremity prosthetic limbs. High-fidelity volitional control of these devices is dependent on the critical interface between the patient and the mechanical prosthesis. Recent innovations in prosthetic interfaces have focused on several control strategies. Targeted muscle reinnervation is currently the most immediately applicable prosthetic control strategy and is particularly indicated in proximal upper extremity amputations. Investigation into various brain interfaces has allowed acquisition of neuroelectric signals directly or indirectly from the central nervous system for prosthetic control. Peripheral nerve interfaces permit signal transduction from both motor and sensory nerves with a higher degree of selectivity. This article reviews the current developments in each of these interface systems and discusses the potential of these approaches to facilitate motor control and sensory feedback in upper extremity neuroprosthetic devices.