Jason H. Ko

Soft polypropylene mesh, but not cadaveric dermis, significantly improves outcomes in midline hernia repairs using the components separation technique

Background: The search continues for the “ideal” repair of the midline ventral hernia, and the components separation technique has a low, but still concerning, hernia recurrence rate. The authors hypothesize that adding prosthetic or bioprosthetic meshes to the midline closure during components separation would reduce recurrence rates with minimal added morbidity. Methods: Over a 3-year period, patients had a components separation procedure where either acellular cadaveric dermis (n = 26) or soft polypropylene mesh (n = 28) was used as an intraperitoneal underlay for reinforcement of the midline repair, but not as a “bridging material.” In 36 operations, the mesh or cadaveric dermis was placed at the time of the components separation, and in the remaining cases (n = 18), the underlay was used to treat a recurrence after components separation. Results: Cadaveric dermis was associated with a 46 percent “true” recurrence rate that required reoperation (mean follow-up, 17.3 months), whereas soft polypropylene mesh had a significantly lower recurrence rate of 11 percent (p = 0.0057) during a follow-up period of 16 months. Because of a higher incidence of concomitant bowel surgery and contamination in the cadaveric dermis group, additional subset analysis of uncontaminated cases was performed, demonstrating a 61 percent recurrence rate for cadaveric dermis compared with 12 percent for soft polypropylene (p = 0.0017). No significant differences in major and minor complications were seen between groups. Conclusion: Soft polypropylene mesh, but not acellular dermis, demonstrates acceptably low complication and hernia recurrence rates when used as a reinforcement of the midline ventral hernia closure in conjunction with components separation.

Targeted Reinnervation for Transhumeral Amputees: Current Surgical Technique and Update on Results

Background: Targeted reinnervation in upper extremity transhumeral amputees can improve control and dexterity of myoelectric prostheses. The operation as described previously required a long residual limb and the presence of a brachialis muscle. Methods: Brachial plexus dissections were performed to confirm and better understand the branching pattern of the radial nerve in the upper arm. A simplified surgical approach for targeted reinnervation in transhumeral amputees was devised. This study reports on the first six transhumeral amputees who have undergone this simplified procedure. Results: The long and lateral heads of the triceps receive distinct and separate motor nerves from the proximal radial nerve. This anatomy allows a nerve transfer of the distal radial nerve to the motor nerve of the lateral head of the triceps without injury to the innervation of the long head of the triceps. The median nerve transfer to the motor branch of the medial head of the biceps is performed on the anterior surface of the arm as described previously. All six patients had successful targeted reinnervation procedures using this simplified approach. Conclusion: Targeted reinnervation for transhumeral amputees can now be performed in patients with amputations at the level of the middle of the humerus or longer.

Does Targeted Nerve Implantation Reduce Neuroma Pain in Amputees

BackgroundSymptomatic neuroma occurs in 13% to 32% of amputees, causing pain and limiting or preventing the use of prosthetic devices. Targeted nerve implantation (TNI) is a procedure that seeks to prevent or treat neuroma-related pain in amputees by implanting the proximal amputated nerve stump onto a surgically denervated portion of a nearby muscle at a secondary motor point so that regenerating axons might arborize into the intramuscular motor nerve branches rather than form a neuroma. However, the efficacy of this approach has not been demonstrated.Questions/purposesWe asked: Does TNI (1) prevent primary neuroma-related pain in the setting of acute traumatic amputation and (2) reduce established neuroma pain in upper- and lower-extremity amputees?MethodsWe retrospectively reviewed two groups of patients treated by one surgeon: (1) 12 patients who underwent primary TNI for neuroma prevention at the time of acute amputation and (2) 23 patients with established neuromas who underwent neuroma excision with secondary TNI. The primary outcome was the presence or absence of palpation-induced neuroma pain at last followup, based on a review of medical records. The patients presented here represent 71% of those who underwent primary TNI (12 of 17) and 79% of those who underwent neuroma excision with secondary TNI (23 of 29 patients) during the period in question; the others were lost to followup. Minimum followup was 8 months (mean, 22 months; range, 8–60 months) for the primary TNI group and 4 months (mean, 22 months; range, 4–72 months) for the secondary TNI group.ResultsAt last followup, 11 of 12 patients (92%) after primary TNI and 20 of 23 patients (87%) after secondary TNI were free of palpation-induced neuroma pain.ConclusionsTNI performed either primarily at the time of acute amputation or secondarily for the treatment of established symptomatic neuroma is associated with a low frequency of neuroma-related pain. By providing a distal target for regenerating axons, TNI may offer an effective strategy for the prevention and treatment of neuroma pain in amputees.Level of EvidenceLevel IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Intrafascicular stimulation of monkey arm nerves evokes coordinated grasp and sensory responses

High-count microelectrode arrays implanted in peripheral nerves could restore motor function after spinal cord injury or sensory function after limb loss. In this study, we implanted Utah Slanted Electrode Arrays (USEAs) intrafascicularly at the elbow or shoulder in arm nerves of rhesus monkeys (n = 4) under isoflurane anesthesia. Input-output curves indicated that pulse-width-modulated single-electrode stimulation in each arm nerve could recruit single muscles with little or no recruitment of other muscles. Stimulus trains evoked specific, natural, hand movements, which could be combined via multielectrode stimulation to elicit coordinated power or pinch grasp. Stimulation also elicited short-latency evoked potentials (EPs) in primary somatosensory cortex, which might be used to provide sensory feedback from a prosthetic limb. These results demonstrate a high-resolution, high-channel-count interface to the peripheral nervous system for restoring hand function after neural injury or disruption or for examining nerve structure.

The effects of targeted muscle reinnervation on neuromas in a rabbit rectus abdominis flap model

PURPOSE A targeted muscle reinnervation (TMR) model was created using a pedicled rabbit rectus abdominis (RA) flap to receive the input from previously amputated forelimb neuromas. We hypothesize that a segmental muscle flap can undergo TMR and that it is possible to differentiate the signal from 3 independent nerves. In addition, by virtue of the nerve coaptation, the morphology of the previous amputation neuroma would become more like that of an in-continuity neuroma. METHODS Five New Zealand white rabbits had a forelimb amputation. In a second-stage surgery, an RA flap was transposed onto the chest wall. After neuroma excision, 3 neurorrhaphies were made between the median nerve, radial nerve, and ulnar nerves, and 3 motor nerves of the RA. After 10 weeks, the electrophysiologic properties of the reinnervated flap were tested. Nerve specimens from the median, radial, and ulnar nerves were harvested before and after TMR to quantify the histomorphometric changes effected by TMR on the mixed nerve neuromas. RESULTS Of the 12 nerve coaptations performed in the 4 viable flaps, all 12 were grossly successful. Muscle surface EMG data demonstrated that the RA retained its segmental innervation pattern after TMR. Similarly, prolonged stimulation of 1 nerve reinnervating the RA resulted in the depletion of glycogen specific to the territory of the muscle stimulated by that nerve. TMR was found to favorably alter the histomorphometric characteristics of the neuroma by decreasing myelinated fiber counts and increasing fascicle diameter in the transferred nerves. CONCLUSIONS This study demonstrates that 1 segmented muscle having TMR by multiple nerve ingrowth and in turn generate discrete EMG signals. During this process, the previous amputation neuroma undergoes favorable morphologic alteration. CLINICAL RELEVANCE Based on these preclinical results, this technique might be useful in upper extremity amputees to recruit target muscles to have reinnervation to drive myoelectric prostheses and to treat symptomatic neuromas.

Limb transplantation and targeted reinnervation: A practical comparison

Limb transplantation and targeted reinnervation are complimentary but very different approaches for restoring function to an upper limb amputee. This article reviews the advantages and limitations of both of these procedures, and highlights the reconstructive obstacles in the treatment of upper limb amputees.

Novel model for end-neuroma formation in the amputated rabbit forelimb

Background The forelimb amputee poses many reconstructive challenges in the clinical setting, and there is a paucity of established surgical models for study. To further elucidate the pathogenic process in amputation neuroma formation, we created a reproducible, well-tolerated rabbit forelimb amputation model. Methods Upon approval from the Institutional Animal Care and Use Committee, 5 New Zealand White rabbits underwent left forelimb amputation. During this initial surgery, the median, radial and ulnar nerves were transected 1.6-2.5 (mean 2.0) cm distal to the brachial plexus, transposed onto the anterior chest wall and preserved at length. Six weeks subsequent to the amputation, the distal 5 mm of each neuroma was excised, and the remaining stump underwent histomorphometric analysis. Results The nerve cross sectional areas increased by factors of 1.99, 3.17, and 2.59 in the median (p = 0.077), radial (p < 0.0001) and the ulnar (p = 0.0026) nerves, respectively. At the axonal level, the number and cross-sectional area of myelinated fibers demonstrated an inverse relationship whereby the number of myelinated fibers in the median, radial and ulnar nerves increased by factors of 5.13 (p = 0.0043), 5.25 (p = 0.0056) and 5.59 (p = 0.0027), and the cross-sectional areas of these myelinated fibers decreased by factors of 4.62 (p < 0.001), 3.51 (p < 0.01), and 4.29 (p = 0.0259), respectively. Conclusion Given that the surgical model appears well-tolerated by the rabbits and that patterns of morphologic change are consistent and reproducible, we are encouraged to further investigate the utility of this model in the pathogenesis of neuroma formation.

Comparing the hydrosurgery system to conventional debridement techniques for the treatment of delayed healing wounds: a prospective, randomised clinical trial to investigate clinical efficacy and cost-effectiveness.

In these uncertain times of high health care costs, clinicians are looking for cost‐effective devices to employ in their everyday practices. In an effort to promote cost‐effective and proper wound repair, the hydrosurgical device allows accurate debridement of only unwanted tissue while precisely conserving viable structures for eventual repair. This prospective, randomised study compared procedures using the hydrosurgery system (VERSAJET™) with conventional debridement in order to assess clinical efficacy and cost‐effectiveness when treating subjects with chronic wounds. A total of 40 subjects were recruited. There was no difference in time to achieve stable wound closure between the treatment groups (P = 0·77). There were no significant differences between the two groups in terms of cost of the first operative procedure (P = 0·28), cost of surgical procedures during the study (P = 0·51), cost of study treatment (P = 0·29) or cost to achieve stable wound closure (P = 0·85). There were no differences in quantitative bacterial counts after debridement with either methods (P = 0·376). However, the time taken for the first excision procedure was significantly faster using the hydrosurgery system (VERSAJET) when compared with conventional debridement (P < 0·001). The total excision time for all procedures was significantly less for the Hydrosurgery group than for the conventional group (P = 0·005). Also, the Hydrosurgery group demonstrated significantly less intraoperative blood loss than conventional group for all procedures (P = 0·003). In this study, although there were no differences in time to stable wound closure or bacterial reduction between the two groups, the hydrosurgery system (VERSAJET) did offer advantages in terms of operative times and intraoperative blood loss and was cost‐neutral, despite the handpiece cost.

Reconstruction of the traumatized thumb.

Background: The goals of thumb reconstruction include the restoration of thumb length, strength, position, stability, mobility, sensibility, and aesthetics. It is a rare event when all of these objectives can be achieved, and prioritization should be based on the goals and functional demands of the patient. Methods: In this article, the authors review the most common reconstructive strategies for all types of traumatic thumb defects. Results: Replantation is approached first as the primary option for most amputations. Nonreplantable injuries are organized using a simple classification adapted from Lister, dividing thumb amputations into four functional categories: soft-tissue deficit with acceptable length, subtotal amputation with borderline length, total amputation with preservation of the carpometacarpal joint, and total amputation with destruction of the carpometacarpal joint. Within each category, relevant microsurgical and nonmicrosurgical reconstructive techniques are discussed, with a focus on appropriate technique selection for a given patient. Evidence and outcomes data are reviewed where available, and case examples from our own experience are provided. Conclusions: Given that available options now range from simple gauze dressings to complex microsurgical reconstruction, preservation of reconstructive flexibility is essential and should be facilitated by judicious preservation of intact structures. The divergence of available reconstructive pathways underscores the importance of knowing one’s patients, understanding their motivation, and assessing their goals. Only in properly matching the right reconstruction with the right patient will a mutually satisfactory result be achieved.

Triangular Fibrocartilage Complex Injuries in the Elite Athlete

Injuries to the triangular fibrocartilage complex (TFCC) in athletes can be caused by acute trauma, chronic repetitive loading, or a combination of both. Regardless of cause, the management of TFCC injuries in the high-performance athlete is often different from the basic tenets applied to the general population. The diagnosis, treatment, and rehabilitation regimen should be individualized and sport-specific in athletes, taking into consideration the priorities and needs of the athlete while striking a balance between healing, return to play, and long-term well-being.