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Summary: Treatment of painful neuromas has long posed a significant challenge for peripheral nerve patients. The regenerative peripheral nerve interface (RPNI) provides the transected nerve with a muscle graft target to prevent neuroma formation. Discrepancies in RPNI surgical techniques between animal models ("inlay" RPNI) and clinical studies ("burrito" RPNI) preclude direct translation of results from bench to bedside and may account for variabilities in patient outcomes. The authors compared outcomes of these 2 surgical techniques in a rodent model. Animals treated with burrito RPNI after tibial nerve neuroma formation demonstrated no improvement in pain assessment, and tissue analysis revealed complete atrophy of the muscle graft with neuroma recurrence. By contrast, animals treated with inlay RPNI had significant improvement in pain with viable muscle grafts. The results suggest superiority of the inlay RPNI surgical technique for the management of painful neuroma in rodents., Clinical Relevance Statement: RPNIs are currently being used to prevent and treat neuroma and phantom limb pain. This preclinical study suggests the superiority of one surgical technique over the other., (Copyright © 2023 by the American Society of Plastic Surgeons.)

Background: Dellon et al. have reported that chronic nerve compression of the tibial nerve inside the tarsal tunnel, caused by diabetes mellitus, can be relieved following open decompression surgery. However, the large skin incision resulting from Dellon's procedure may cause wound healing problems. The authors report the possibility of a minimally invasive full endoscopic procedure., Methods: Operations were performed under local anesthesia without a pneumatic tourniquet. An anesthetic agent was applied at the proximal part of the flexor retinaculum of the foot, and a hypodermic needle was advanced into the tarsal tunnel. Tarsal tunnel pressure and blood circulation of the tibial nerve using indocyanine green assessment were measured preoperatively. One 1-cm portal skin incision was made at the anesthetized area and the Universal Subcutaneous Endoscope system was inserted into the tarsal tunnel. The flexor retinaculum, tibial nerve, blood vessels, and abductor hallucis muscle fascia were identified under endoscopic observation. After decompression of the tarsal tunnel, the authors measured tarsal tunnel pressure and blood circulation of the tibial nerve for analysis of the effectiveness of the endoscopic decompression during the procedure., Results: Fourteen operations were compiled and analyzed. Postoperative clinical status was improved based on the preoperative modified Toronto Clinical Neuropathy Score. The mean tarsal tunnel pressure dropped to 4.5 mmHg during surgery from the initial preoperative 49.4 mmHg in resting position. Endoscopic indocyanine green assessment showed more than 30 percent improvement of the vascularity surrounding the tibial nerve., Conclusion: The authors' minimally invasive full endoscopic procedure is a viable alternative approach for tarsal tunnel syndrome patients with diabetic foot neuropathy., Clinical Question/level of Evidence: Therapeutic, IV., (Copyright © 2021 by the American Society of Plastic Surgeons.)

Background: Although there was initial success using tibial nerve transfer to restore ankle dorsiflexion following peroneal nerve injury, results from later series were less promising. A potential reason is coactivation of the much stronger antagonistic muscles during gait. The purpose of this study was to test the hypothesis that gait training would improve functional performance following tibial nerve transfer., Methods: Using a prospective, nonrandomized, controlled study design, patients were divided into two groups: surgery only or surgery plus gait training. Of the 20 patients who showed reinnervation in the tibialis anterior muscle, 10 were assigned to the gait training group, and an equal number were in the control group. Those in the treatment group began training once reinnervation in the tibialis anterior muscle was detected, whereas those in the control group continued to use their ankle-foot orthosis full time. Differences in ankle dorsiflexion were measured using the Medical Research Council scale, and quantitative force measurement and functional disability was measured using the Stanmore Scale., Results: Patients in the gait training group attained significantly better functional recovery as measured by the Stanmore Scale (79.5 ± 14.3) (mean ± SD) versus (37.2 ± 3.5) in the control group (p = 0.02). Medical Research Council grades were 3.8 ± 0.6 in the training group versus 2.5 ± 1.2 in the surgery only group (p < 0.05). Average dorsiflexion force from patients with above antigravity strength (all from the training group) was 31 percent of the contralateral side., Conclusion: In patients with successful reinnervation following tibial nerve transfers, rehabilitation training significantly improved dorsiflexion strength and function., Clinical Question/level of Evidence: Therapeutic, II., (Copyright © 2021 by the American Society of Plastic Surgeons.)

Background: There is clinical and experimental evidence that botulinum toxin applied to the healthy side of patients with facial paralysis positively affects functional recovery of the paralyzed side. The authors created an experimental model to study the effects of botulinum toxin injection in the gastrocnemius muscle contralateral to the side of tibial nerve lesion/repair in rats., Methods: Fifty rats were allocated into five groups: group I, control; group II, tibial nerve section; group III, tibial nerve section and immediate neurorrhaphy; group IV, tibial nerve section, immediate neurorrhaphy, and botulinum toxin injected into the contralateral gastrocnemius muscle; and group V, botulinum toxin injected into the gastrocnemius muscle and no surgery. Assessment tools included a walking track, electromyography, gastrocnemius muscle weight measurement, and histologic analysis of the nerve., Results: Paralysis in group V was transient, with function returning to normal at 8 weeks. At 12 weeks, group V had lower latency levels. At week 12, group IV showed higher functional outcomes and amplitude levels than group III, and lower muscle atrophy on the side injected with botulinum toxin compared with group V., Conclusion: Transient paralysis of the contralateral gastrocnemius muscle by botulinum toxin type A improved functional recovery in rats that underwent section and repair of the tibial nerve.

Background: Absence of plantar sensation is a critical factor considered in favor of amputation for patients with lower limb-threatening injuries. This study aims to assess outcomes of limb salvage in a group of patients with severe lower extremity injuries associated with posterior tibial nerve transection., Methods: The authors studied eight cases of limb salvage after traumatic injuries with documented tibial nerve laceration managed at Ganga Hospital, India. Functional and health-related quality-of-life outcomes were assessed. Outcomes from this case series were compared to outcomes of studies from a systematic literature review on salvage of the severely injured lower extremity., Results: Patients in this case series reported mild pain (median score, 20 on a visual analogue scale ranging from 0 to 100), with some return of plantar sensation in patients with tibial nerve repairs (median score, 2 of 5). Patients demonstrated a decrease in ankle motion (27.5 degrees' plantar flexion and 10 degrees' extension) and muscle strength (median heel flexor score, 3 of 5). All patients could ambulate independently. Quality of life and function measured by validated instruments revealed minimal disability. The authors identified 1767 articles on lower extremity trauma, and 14 articles were reviewed systematically. Relative to the case series, published articles reported similarly diminished ankle motion and muscle strength, with reports of mild pain in select studies. Patient-reported outcomes instruments found variations in the degree of physical disability based on the time from injury., Conclusion: Although limited in number, this case series demonstrates the value of limb salvage even for patients with posterior tibial nerve injury.

Background: Long-term muscle denervation leads to severe and irreversible atrophy coupled with loss of force and motor function. These factors contribute to poor functional recovery following delayed reinnervation. The authors' previous work demonstrated that temporarily suturing a sensory nerve to the distal motor stump (called sensory protection) significantly reduces muscle atrophy and improves function following reinnervation. The authors have also shown that 1 month of electrical stimulation of denervated muscle significantly improves function and reduces atrophy. In this study, the authors tested whether a combination of sensory protection and electrical stimulation would enhance functional recovery more than either treatment alone., Methods: Rat gastrocnemius muscles were denervated by cutting the tibial nerve. The peroneal nerve was then sutured to the distal tibial stump following 3 months of treatment (i.e., electrical stimulation, sensory protection, or both). Three months after peroneal repair, functional and histologic measurements were taken., Results: All treatment groups had significantly higher muscle weight (p<0.05) and twitch force (p<0.001) compared with the untreated group (denervated), but fiber type composition did not differ between groups. Importantly, muscle weight and force were significantly greater in the combined treatment group (p<0.05) compared with stimulation or sensory protection alone. The combined treatment also produced motor unit counts significantly greater than sensory protection alone (p<0.05)., Conclusions: The combination treatment synergistically reduces atrophy and improves reinnervation and functional measures following delayed nerve repair, suggesting that these approaches work through different mechanisms. The authors' research supports the clinical use of both modalities together following peripheral nerve injury.

Background: An original surgical technique for the correction of drop foot is demonstrated., Methods: Eighteen patients with drop foot underwent transfer of the lateral, medial, or both heads of the gastrocnemius muscle to the tendons of the anterior and/or lateral muscle group of the lower leg. The transferred muscle was reinnervated by nerve coaptation between the undamaged proximal part of the deep peroneal nerve and the motor branch of the tibial nerve supplying the gastrocnemius muscle., Results: In all patients, the transferred gastrocnemius muscle showed signs of reinnervation within an average of 6 months after operation. Ten patients achieved excellent results, having regained stable, fully automatic walking without foot inversion/eversion and active range of foot movement of at least 40 degrees. Four patients achieved good results with active range of movement of less than 40 degrees but very stable functional gait. Satisfactory results were presented in three cases with stable ankle motion. Two of three cases had dual transfer of the gastrocnemius muscle and had a very stable ankle joint. In one fair case, the treatment improved stability and the patient was able to walk., Conclusions: To compensate for the loss of function of the anterior muscle compartment, neuromusculotendinous transfer of the gastrocnemius muscle has proved to be highly successful. Voluntary movement of the transferred muscle and fully automatic walking was achieved in the majority of patients treated. In contrast to the commonly used treatment of tibialis posterior muscle transfer, no reeducation of the transferred muscle was needed.

Background: Skeletal muscle structure and function are dependent on intact innervation. Prolonged muscle denervation results in irreversible muscle fiber atrophy, connective tissue hyperplasia, and deterioration of muscle spindles, specialized sensory receptors necessary for proper skeletal muscle function. The protective effect of temporary sensory innervation on denervated muscle, before motor nerve repair, has been shown in the rat. Sensory-protected muscles exhibit less fiber atrophy and connective tissue hyperplasia and maintain greater functional capacity than denervated muscles. The purpose of this study was to determine whether temporary sensory innervation also protects muscle spindles from degeneration., Methods: Rat tibial nerve was transected and repaired with either the saphenous or the original transected nerve. Negative controls remained denervated. After 3 to 6 months, the electrophysiologic response of the nerve to stretch in the rat gastrocnemius muscle was measured (n = 3 per group). After the animals were euthanized, the gastrocnemius muscle was removed, sectioned, stained, and examined for spindle number (n = 3 per group) and morphology (one rat per group). Immunohistochemical assessment of muscle spindle innervation was examined in four additional animals., Results: Significant deterioration of muscle spindles was seen in denervated muscle, whereas in muscle reinnervated with the tibial or the saphenous nerve, spindle number and morphology were improved. Histologic and functional evidence of spindle reinnervation by the sensory nerve was obtained., Conclusion: These findings add to the known means by which motor or sensory nerves exert protective effects on denervated muscle, and further promote the use of sensory protection for improving the outcome after peripheral nerve injury.

Background: Replantation surgery in lower extremity amputations continues to be controversial. Overall results have been considered poor and the procedure is usually discouraged. It is the opinion of the authors that infrapopliteal replantation may be indicated., Methods: A series of 12 patients with 13 amputations through the tibia or below were treated with replantation of the parts. The main indication was an intact sole and amenability of direct tibial nerve repair. Extensive bone loss or soft-tissue damage was not a contraindication. All replantations were orthotopic, and in one case a temporary ectopic replantation was performed. All transtibial replantations underwent subsequent bone lengthening (8 to 13 cm)., Results: The survival rate of the replanted segments was 100 percent. There was one death caused by pulmonary thromboembolism. The number of additional operations was 3.1 (range, one to five). Soft-tissue necrosis occurred in 83 percent of cases, requiring flap coverage. A free flap was used in 90 percent of these cases, with a 100 percent success rate. Chen functional grade was I or II (good or excellent) in all but one case. Treatment time averaged 11.3 months (range, 8 to 16 months). No delayed amputations or plantar ulcers occurred., Conclusions: Although the complication rate has been high, in dedicated teams and with proper selection of patients, replantation of infrapopliteal lower limb amputations can yield satisfactory results.

Background: The sciatic nerve is composed of two independent divisions: tibial and peroneal. The results of the repair of these two nerves are not identical. This retrospective study was carried out with the aim of evaluating the results of different therapeutic procedures for sciatic nerve injuries and conducting a comparative evaluation of peroneal and tibial nerve recovery., Methods: A total of 648 Iranian casualties of the 1980 to 1988 Iran-Iraq war with sciatic nerve injury were treated with nerve grafting, direct end-to-end coaptation, and neurolysis. Patients were subdivided according to nerve injury site into three groups of upper, middle, and lower thirds of the thigh, and followed from 5 to 12 years., Results: In 77.8 percent of patients, the tibial nerve was injured, and in 88.9 percent, the common peroneal nerve was injured. Protective sensation recovery of the sole was evaluated as good in 69.1 percent of those with upper third injuries, 74.4 percent of those with middle third injuries, and 89.3 percent of those with lower third repairs (p < 0.0001), with an overall success rate of 73.4 percent. The overall motor recovery success rate for the three techniques was 86.3 percent for the tibial nerve and 38.9 percent for the common peroneal nerve., Conclusions: Results of sciatic nerve injury treatment in this group of war casualties were generally satisfactory. Tibial nerve injury repair in the upper thigh has a higher priority than the peroneal nerve. Motor deficits of the common peroneal nerve can be overcome by tendon transfer or orthopedic devices.

Background: Over the past decade, a growing body of literature has emerged supporting the use of end-to-side (terminolateral) neurorrhaphy for the treatment of selected peripheral nerve injuries. It remains unclear, however, whether injury to the donor nerve is necessary to achieve significant regeneration through such repairs., Methods: End-to-side repair was studied in a rodent model in which the terminal limb of a transected peroneal nerve was sutured to the lateral aspect of the tibial nerve. Twenty-eight Lewis rats were randomized to four groups of seven animals each corresponding to incrementally greater donor nerve injuries as follows: group 1, conventional end-to-side neurorrhaphy; group 2, end-to-side neurorrhaphy with proximal crush injury; group 3, end-to-side neurorrhaphy with neurotomy; and group 4, end-to-end repair of transected peroneal nerve (positive control)., Results: At 12 weeks, retrograde labeling of cell bodies of the ventral horn demonstrated significant differences between experimental groups, with mean counts in group 4 (1237 +/- 171) > group 3 (522 +/- 204) > group 2 (210 +/- 132) > or = group 1 (126 +/- 146). This association between nerve injury and motor neuron counts was closely mirrored in quantitative assessments of peripheral nerve regeneration and normalized wet muscle masses., Conclusions: These data support the hypothesis that donor nerve injury is a prerequisite for significant motor neuronal regeneration across end-to-side repairs. Motor neuron regeneration through end-to-side repairs is optimized by deliberate transection of donor nerve axons.

Background: Many Asian women are bothered by plump calves, which they consider to be unsightly. In the past, liposuction was frequently performed to treat oversized legs, but little effect could be obtained if the condition was caused by hypertrophy of calf muscles., Methods: Gastrocnemius muscle resection for hypertrophic muscular calves was performed in 20 patients at Buddhist Tzu Chi General Hospital from May of 2001 through September of 2004. One patient underwent resection of the medial head only, two underwent total resection of both medial and lateral heads, and the other 17 patients underwent subtotal resection with preservation of the proximal 4 to 6 cm of muscle of both heads., Results: The resected gastrocnemius muscle weighed from 250 to 430 g per calf (mean, 343 g). The maximal calf circumference was between 32 and 41 cm (average, 35.2 cm) preoperatively and 26 and 35 cm (average, 30.5 cm) postoperatively. Calf reduction was 3.5 to 7 cm (average, 4.7 cm), or 10.1 to 21.2 percent (average, 13.3 percent). Two patients developed seroma and three developed late hematoma. One patient had dragging of one foot because of incidental severance of the nerve to the soleus muscle that lasted for 6 months, until complete recovery occurred. No patient complained of functional deficits during gait or sports activities after 3 to 6 months., Conclusions: Subtotal resection of both heads of the gastrocnemius muscle can result in satisfactory calf reduction without impairment of leg function and avoid hollow deformity in the popliteal fossa. Five patients still had scar problems during the short-term follow-up period, but all were rather satisfied with their reduced calf sizes.

Background: FK-506 is used in organ transplantation because it promotes neurite outgrowth in vitro and enhances neuroregeneration in peripheral nerve injury transection models. Immunosuppressive mechanisms of FK-506 are well defined, with demonstration of decreased neuroregenerative effects with delayed administration. The purpose of this study was to describe the effects of preinjury administration of FK-506 in rats with tibial nerve transection injury., Methods: Eight inbred male Lewis rats per group in three separate groups underwent tibial nerve transection with primary repair. Group I received placebo, group II received FK-506 treatment at 1 day before surgery, and group III received FK-506 preloading 3 days before surgery., Results: Histologic and histomorphometric results demonstrated the preload FK-506 group had superior results compared with the immediate FK-506 group. Both FK-506 groups were superior to the placebo group. The preload FK-506 demonstrated superior regeneration in mean total nerve fiber counts (p < 0.05), greater percentage neural tissue (p < 0.05), greater mean nerve fiber density (p < 0.05), and lower percentage of debris (p > 0.05). Mean nerve fiber widths were similar in the preload and immediate FK-506 groups but superior to the placebo group., Conclusion: These data suggest that enhancement of FK-506's neuroregenerative effect is enhanced when administered before nerve injury such as when performing elective surgery.

Using a rat hindlimb model, the authors tested the hypothesis that, in muscles reinnervated after long-term denervation, atrophy-dependent and atrophy-independent mechanisms operate independently to produce force deficits. In adult rats, gastrocnemius muscles were subjected to denervation via tibial nerve transection. Reconstruction of the nerve lesion was delayed for periods ranging from 2 weeks to 1 year. After a minimum recovery period of 6 months after nerve repair, muscle mass and maximum isometric tetanic force were measured and specific force was calculated for each muscle (n = 40 muscles from 23 animals). After recovery, observed deficits in muscle mass and maximum tetanic force were directly proportional to the denervation interval. On the other hand, the deficit in specific force was not proportional to the denervation interval; all groups in which the nerve reconstruction was delayed for a month or longer demonstrated a deficit of 30 percent to 50 percent. These data support our hypothesis that, after prolonged denervation followed by reinnervation, the magnitude of the deficit in whole muscle force does not parallel the deficit in specific force. These data support the idea that mechanisms governing muscle atrophy are independent of those resulting in specific force deficits.

Potential donor nerves for autografting are finite and usually limited to cutaneous nerves of the extremities. The superficial peroneal nerve is the major lateral branch of the common peroneal nerve that innervates the peroneus longus and brevis muscles and provides sensation to the lateral aspect of the lower leg and the dorsal foot. It has generally been overlooked as a potential donor of nerve autografts. Cadaver dissections were performed on 10 fresh lower extremity specimens to investigate the anatomic characteristics of the superficial peroneal nerve and to refine a harvesting technique for the nerve. Thirty-one patients underwent nerve grafting of 39 upper and lower extremity nerves using the superficial peroneal donor. There were nine median nerves, four ulnar nerves, two radial nerves, two brachial plexus lesions, 16 digital nerves, and six lower extremity nerves grafted. The superficial peroneal nerve provided a consistently long donor, comparable in length to the sural nerve. The anatomic pattern is consistent, the patient positioning is simple, the surgical harvesting technique is straightforward, and the donor defect is acceptable. The superficial peroneal nerve provides a safe and valuable donor nerve, particularly in cases where multiple or very long nerve grafts are required.

End-to-end nerve coaptation is the preferred surgical technique for peripheral nerve reconstruction after injury or tumor extirpation. However, if the proximal nerve stump is not available for primary repair, then end-to-side neurorrhaphy may be a reasonable alternative. Numerous studies have demonstrated the effectiveness of this technique for muscle reinnervation. However, very little information is available regarding the potential adverse sequelae of end-to-side neurorrhaphy on the innervation and function of muscles innervated by the "donor" nerve. End-to-side neurorrhaphy is hypothesized to (1) acutely produce partial donor muscle denervation and (2) chronically produce no structural or functional deficits in muscles innervated by the donor nerve. Adult Lewis rats were allocated to one of two studies to determine the acute (2 weeks) and chronic (6 months) effects of end-to-side neurorrhaphy on donor muscle structure and function. In the acute study, animals underwent either sham exposure of the peroneal nerve (n = 13) or end-to-side neurorrhaphy between the end of the tibial nerve and the side of the peroneal nerve (n = 7). After a 2-week recovery period, isometric force (F(0) was measured, and specific force (sF(0) was calculated for the extensor digitorum longus muscle ("donor" muscle) for each animal. Immunohistochemical staining for neural cell adhesion molecule (NCAM) was performed to identify populations of denervated muscle fibers. In the chronic study, animals underwent either end-to-side neurorrhaphy between the end of the peroneal nerve and the side of the tibial nerve (n = 6) or sham exposure of the tibial nerve with performance of a peroneal nerve end-to-end nerve coaptation approximately 6), to match the period of anterior compartment muscle denervation in the end-to-side neurorrhaphy group. After a 6-month recovery period, contractile properties of the medial gastrocnemius muscle ("donor" muscle) were measured. Acutely, a fivefold increase in the percentage of denervated muscle fibers (1 +/0 0.7 percent to 5.4 +/-2.7 percent) was identified in the donor muscles of the animals with end-to-side neurorrhaphy (p < 0.001). However, no skeletal muscle force deficits were identified in these donor muscles. Chronically, the contractile properties of the medial gastrocnemius muscles were identical in the sham and end-to-side neurorrhaphy groups. These data support our two hypotheses that end-to-side neurorrhaphy causes acute donor muscle denervation, suggesting that there is physical disruption of axons at the time of nerve coaptation. However, end-to-side neurorrhaphy does not affect the long-term structure or function of muscles innervated by the donor nerve.

Despite highest standards in nerve repair, functional recovery following nerve transection still remains unsatisfactory. Nonspecific reinnervation of target organs caused by misdirected axonal growth at the repair site is regarded as one reason for a poor functional outcome. This study was conducted to establish a method for preventing aberrant reinnervation between transected and repaired nerves in adjacency. Rat sciatic nerve was transected and repaired as follows: epineural sutures of the sciatic nerve (group A, n = 6), fascicular repair of tibial and peroneal nerves respectively (group B, n = 8), and, as in group B, separating both nerves using a pedicle fat flap as barrier (group C, n = 8). As control only, the tibial nerve was transected and repaired (group D, n = 5). Muscle contraction force of the gastrocnemius muscle was significantly higher in group C as compared with groups A and B after 4 months. Muscle weight showed significantly lower values in group A as compared with groups B, C, and D. Histologic examination in group C revealed little growth of axons from the tibial to the peroneal nerve and vice versa. This axon crossing was observed only when gaps between the fat cells were available. These findings were confirmed by a significantly lower rate of misdirected axonal growth as compared with groups A and B using sequential retrograde double labeling technique of the soleus motoneuron pool. We conclude that a pedicle fat flap significantly prevents aberrant reinnervation between repaired adjacent nerves resulting in significantly improved motor recovery in rats. Clinically, this is of importance for brachial plexus, sciatic nerve, and facial nerve repair.

End-to-side neurorrhaphy is a surgical technique for peripheral nerve reconstruction when end-to-end neurorrhaphy is not an option. To define the effectiveness of end-to-side neurorrhaphy as a method of nerve repair, the authors tested the null hypothesis: there is no difference in the mechanical function of skeletal muscle denervated and reinnervated by end-to-side versus end-to-end neurorrhaphy. Adult Lewis rats underwent either transection and end-to-end epineurial repair of the left peroneal nerve (n = 9) or end-to-side repair of the distal stump of the peroneal nerve to the side of the tibial nerve (n = 8). After a 6-month recovery period, isometric force (Fo) was measured, and specific force (sFo) was calculated for the extensor digitorum longus muscle of each animal. Immunohistochemical staining for neural cell adhesion molecule (NCAM) was performed to identify populations of denervated muscle fibers. The mean extensor digitorum longus muscle mass in the end-to-end group (195 +/- 32 g) was significantly greater than that of the end-to-side group (146 +/- 55 g) (p < 0.05). A significantly greater percentage of denervated fibers was identified in the extensor digitorum longus muscles of animals in the end-to-side group (9.4 +/- 3.2 percent) than in those in the end-to-end group (3.8 +/- 1.0 percent) (p < 0.05). Despite a lower muscle mass and a higher percentage of denervated fibers, neither Fo nor sFo was significantly different in the two groups. These data support the null hypothesis that, under appropriate circumstances, there is no difference in the recovery of whole muscle force and specific force production in muscles reinnervated by end-to-side versus end-to-end neurorrhaphy.

Although bipolar cautery was designed to minimize trauma to the central nervous system, little is known about the effects of bipolar cautery on peripheral nerve tissue. This experiment was designed to study the effect of direct bipolar cautery on a peripheral nerve and the muscles innervated by that nerve. Lewis rats (n = 200) were assigned to five different groups: control, sham, and three cautery groups (duration of either 0.5, 1.0, or 1.5 seconds). The hind limb tibial nerves were isolated in the sham group and isolated and cauterized in the cautery groups. Assessments performed at 2 hours, 2 weeks, 4 weeks, and 8 weeks postoperatively included isometric contractile function studies of both a fast- and a slow-twitch muscle, muscle weights, and nerve histology/morphometry. Significant muscle weight loss and reduced muscle function were found in the cautery groups at 2, 4, and 8 weeks (p < 0.05). Histologically, the nerves of the cautery groups showed nerve damage consistent with Sunderland's type 4 nerve injury when examined at 2 weeks and showed nerve regeneration at 4 and 8 weeks. Both the fast-twitch muscle and the shorter duration cautery were associated with faster recovery relative to the slow-twitch muscles and longer duration cautery, respectively. Bipolar cautery, as administered to rat tibial nerves in this experiment, is associated with a significant injury to the nerve and loss of function of the muscles innervated by the nerve.

We investigated the results of postoperative administration of cis-diaminedichloroplatinum on nerve regeneration in rats. Forty-two Lewis rats were divided into two groups, receiving end-to-end suture or nerve grafting. Subgroups of the suture group included control, a one-time dose of cis-diaminedichloroplatinum (3 mg/kg), and four doses of the same amount of cis-diaminedichloroplatinum. Subgroups in the nerve grafting group included a control and a four-dose group. Functional recovery was measured by gait analysis using the tibial function index. Biopsies of nerve were taken distal to the suture site for histologic evaluation 20 weeks postoperatively. Tibial function index at 4, 6, and 20 postoperative weeks in the four-dose group was significantly inferior to that of the control group in the suture group. Tibial function index was inferior in the four-dose group until 10 weeks postoperatively compared with control in the nerve grafting group; however, there was no significant difference. The percentage of neural tissue in the one-dose suture group was significantly greater than in the four-dose suture group. These results suggest that postoperative cis-diaminedichloroplatinum administration may have a detrimental effect on nerve regeneration.

The purpose of this study was to evaluate the immediate effect on capillary blood flow of surgical mobilization of 15 cm of the rabbit sciatic and tibial nerve. Capillary nerve blood flow was determined with 16-micron radioactive microspheres. Thirty-seven rabbits were divided into six groups. In the control group A (n = 7), the in situ nerve blood flow was determined. In group B (n = 7), the nerve was mobilized, leaving only the proximal and distal endoneurial vascular supplies; blood flow increased compared with in situ values in most segments. In group C (n = 5), the nerve was mobilized as in group B, but also transected distally; blood flow was markedly decreased in the distal segments but was maintained up to a diameter-to-length ratio of 1:63. In group D (n = 6), the nerve was not mobilized, but was transected proximally and distally; blood flow increased in all segments. In group E (n = 5), the nerve was mobilized and transected proximally and distally, leaving only nerve branches intact; blood flow was significantly higher in segments of the nerve from which nerve branches originated with the nerve receiving blood flow through its branches. In group F (n = 6), the nerve was mobilized, all extrinsic vessels except one were transected, and the proximal and distal nerve was transected; flow was maintained to a diameter:length ratio of 1:41 from the source of blood flow. Therefore, it does appear that long lengths of nerve may be mobilized and transposed while maintaining sufficient blood flow.

Over a 12-year period between 1979 and 1991, 27 patients were operated on at the New York University Medical Center for salvage of below-knee amputation stumps utilizing free flaps. Six different donor sites were used. In 6 patients, the amputated foot was the donor site for a free flap to cover the tibial stump. There were 3 males and 3 females in this group. Five of the patients underwent immediate filet of foot reconstructions, while 1 patient had a reconstruction performed 69 days after injury, electively, when it was determined that below-knee amputation was the best option. All foot flaps survived and ultimately provided the major soft-tissue coverage for the below-knee amputation stump. The length of hospitalization ranged from 24 to 118 days. The time required from foot filet procedure to ambulation was 2, 4, 6, 7, 9, and 12 months in the 6 patients. Five of the 6 patients have resumed work or school after their injury. Foot flaps were based on the posterior tibial artery, anterior tibial artery, or both vessels. Nerve anastomosis of the posterior tibial nerve was performed in 5 patients. In 1 patient it was possible to maintain the continuity of the posterior tibial nerve. Five of the 6 patients were tested over a year after the flap, and all have good cold, pressure, and vibration sensation. Two of the 5 patients have heat sensation, and all 5 patients have at least protective pressure sensation. All the patients ambulate well with a below-knee prosthesis.

Terminolateral neurorrhaphies were used up to the beginning of this century. After that, they were no longer reported. We tested the efficacy of a new type of end-to-side neurorrhaphy. A group of 20 rats had the peroneal nerve sectioned, and the distal ending was sutured to the lateral face of the tibial nerve after removing a small epineural window. All experiments were made on the right side, the left one remaining untouched in half the animals of each group. The other half was denervated by sectioning and inverting the endings of the peroneal nerves. In this way, tibial cranial muscles were either normal or denervated on the left side and reinnervated through end-to-side neurorrhaphies on the right side. After 7.8 months, the animals were subjected to electrophysiologic tests, sacrificed, and the nerves and muscles were taken for histologic examination. A response of the tibial cranial muscle was obtained in 90 percent of the animals. The distal ending of the peroneal nerve showed an average of 861 nerve fibers. The average areas of the reinnervated tibial cranial muscles were (microns 2) 1617.81 for M2n (when the contralateral side was normal) and 1579.19 for M2d (when the contralateral was denervated). We conclude that the terminolateral neurorrhaphy is functional, conducting electrical stimuli and allowing the passage of axons from the lateral surface of a healthy nerve, to reconstitute the distal segment of a sectioned nerve. The absence of an incision on the axons of the donor nerve was no impediment to axonal regeneration or to the passage of electrical stimuli. The results demonstrate the possibility of using end-to-side and terminolateral neurorrhaphies for reconstituting neural lesions when only a distal end is available; the reinnervation can be obtained from the lateral face of a healthy nerve.

An experimental study was performed to assess fetal nerve repair and regeneration both qualitatively and quantitatively. The posterior tibial nerves in one hindlimb were transected in 16 midgestational fetal lambs and in their mothers. The nerves were then repaired with epineurial sutures and allowed to progress to 2, 4, 6, and 8 weeks postinjury. Qualitative assessment was performed through standard nerve histologic staining, including Luxol fast and toluidine blue for myelin and Bielschowsky stain for axons, and quantitative assessment through nerve conduction velocity studies and morphometry to determine mean myelinated fiber diameter, total fiber number, and density. A frequency histogram of the distribution of myelinated nerve fibers according to fiber diameter also was generated. In our model, the subsequent fetal nerve response to injury was characterized by earlier degeneration than in the adult counterparts. Repair and regeneration proceeded with dense collagenous scar formation in both groups. Electrophysiologic studies showed nerve impulse conduction across the repair site only at 6 and 8 weeks postinjury in both fetus and adult. Action potential amplitudes at 6 and 8 weeks were measured at 3 to 5 percent of control nerves in both nerve types. No electrophysiologic differences in the recovery of the injured fetal and adult nerves could be identified. Morphometry revealed that fetal nerve regeneration appeared to occur at a rate equivalent to that of the adult, although by 8 weeks the total percentage of remyelinated nerves appeared more complete in the fetus than in the adult (87 versus 59 percent), suggesting that fetal nerves may have a more favorable regenerative capacity than their adult counterparts.

A case of immediate stump reconstruction following proximal leg amputation below the knee is reported. Additional length and sensation are conferred to the stump by free autotransplantation of a composite flap taken from the unsalvageable amputated leg. This flap provided 13 cm of vascularized tibia invested in the skin of the foot. This operative procedure facilitated the fitting of a prosthesis and preserved knee function despite an initial very proximal amputation.

The progress of contemporary medicine and operative techniques makes it possible to successfully perform the simultaneous replantation of major segments of two extremities, especially in young patients, taking into consideration their high biologic potential. An adequate antishock management, hemotransfusion therapy in particular, at all stages of treatment is an indispensable condition of a favorable outcome of such operations. The method of lengthening the extremities using a distraction apparatus is rather promising for the improvement of functional results of replantations of major segments of the lower extremities. The use of this method makes it possible to broaden the scope of indications for such operations.