Reconstruction after pan-plexus root avulsions often includes gracilis free functioning muscle tr... more Reconstruction after pan-plexus root avulsions often includes gracilis free functioning muscle transfer. For elbow flexion reconstruction, the free functioning muscle transfer distal tendon is inserted into the biceps tendon or more distally (i.e., flexor digitorum profundus/flexor pollicis longus tendons) for combined elbow and finger flexion; the theoretical drawback of the latter approach is weaker elbow flexion. The authors compared elbow flexion strength with a biceps tendon versus a flexor digitorum profundus/flexor pollicis longus tendon attachment to determine which insertion point resulted in better elbow flexion. Thirty-nine patients underwent free functioning muscle transfer with either a biceps tendon or a distal attachment. Groups were compared on postoperative elbow flexion strength, preoperative and postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire scores, range of motion, and other surgical and demographic characteristics. A biomechanical analys...
The aim of this study is to quantify the length of the axillary nerve (AN) that is able to be dis... more The aim of this study is to quantify the length of the axillary nerve (AN) that is able to be dissected through a standard anterior (deltopectoral) and posterior approach. We hypothesize that a segment of the AN cannot be reached using both approaches simultaneously. ANs of 5 frozen cadavers were dissected using an anterior and posterior approach. A first surgical clip marked the most visible distal part of the nerve from the deltopectoral approach; a second surgical clip marked the most proximal part from the posterior approach. The two surgical clips were localized with a shoulder radiograph. We performed measurements of the different AN segments. In all specimens there were three zones of the AN. Zone A (anterior): nerve segment from the origin of the AN to the first surgical clip, located at the level of the triangle formed by the subscapularis muscle (medial), conjoined tendon (lateral) and axillary fat (inferior). Zone B (blind - nerve segment not reachable through both approa...
After complete five-level root brachial plexus injury, free functional muscle transfer and interc... more After complete five-level root brachial plexus injury, free functional muscle transfer and intercostal nerve transfer to the musculocutaneous nerve are two potential reconstructive options for elbow flexion. The aim of this study was to determine the outcomes of free functional muscle transfer versus intercostal nerve-to-musculocutaneous nerve transfers with respect to strength. Sixty-two patients who underwent free functional muscle transfer reconstruction or intercostal nerve-to-musculocutaneous nerve transfer for elbow flexion following a pan-plexus injury were included. The two groups were compared with respect to postoperative elbow flexion strength according to the British Medical Research Council grading system; preoperative and postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire scores. In the free functional muscle transfer group, 67.7 percent of patients achieved M3 or M4 elbow flexion. In the intercostal nerve-to-musculocutaneous nerve transfer group, ...
Isometric tetanic muscle force has been described in a rat model to evaluate motor recovery in a ... more Isometric tetanic muscle force has been described in a rat model to evaluate motor recovery in a segmental sciatic nerve defect reconstructions. However, to test longer nerve defects, an alternative and larger animal model is necessary. The purpose of this study is to describe and validate a technique for isometric force measurement of the tibialis anterior (TA) muscle in New Zealand rabbits. Muscle preload and electrical stimulation parameters were optimized to obtain the highest tetanic contraction bilaterally in 10 animals. Electrophysiology, muscle weight, peroneal nerve length, and histomorphometry were also analyzed. Only the peroneal nerve length and the ratio of highest muscle force/muscle weight demonstrated the equivalence between the sides. A small variability of TA muscle force and TA muscle weight was observed between the sides suggesting dominance. Optimization of electrical stimulation and preload as well as the use of correct anesthesia were fundamental to acquire the highest muscle force.
An effective alternative to nerve autograft is needed to minimize morbidity and solve limited-ava... more An effective alternative to nerve autograft is needed to minimize morbidity and solve limited-availability issues. We hypothesized that the use of processed allografts and collagen conduits would allow recovery of motor function that is equivalent to that seen after the use of autografts. Sixty-five Lewis rats were divided into three experimental groups. In each group, a unilateral 10-mm sciatic nerve defect was repaired with nerve autograft, allograft treated by AxoGen Laboratories, or a 2.0-mm-inner-diameter collagen conduit. The animals were studied at twelve and sixteen weeks postoperatively. Evaluation included bilateral measurement of the tibialis anterior muscle force and muscle weight, electrophysiology, assessment of ankle contracture, and peroneal nerve histomorphometry. Muscle force was measured with use of our previously described and validated method. Results were expressed as a percentage of the values on the contralateral side. Two-way analysis of variance (ANOVA) corrected by the Ryan-Einot-Gabriel-Welsch multiple range test was used for statistical investigation (α = 0.05). At twelve weeks, the mean muscle force (and standard deviation), as compared with that on the contralateral (control) side, was 45.2% ± 15.0% in the autograft group, 43.4% ± 18.0% in the allograft group, and 7.0% ± 9.2% in the collagen group. After sixteen weeks, the recovered muscle force was 65.5% ± 14.1% in the autograft group, 36.3% ± 15.7% in the allograft group, and 12.1% ± 16.0% in the collagen group. Autograft was statistically superior to allograft and the collagen conduit at sixteen weeks with regard to all parameters except histomorphometric characteristics (p < 0.05). The collagen-group results were inferior. All autograft-group outcomes improved from twelve to sixteen weeks, with the increase in muscle force being significant. The use of autograft resulted in better motor recovery than did the use of allograft or a collagen conduit for a short nerve gap in rats. A longer evaluation time of sixteen weeks after segmental nerve injuries in rats would be beneficial as more substantial muscle recovery was seen at that time.
Large segmental osseous defects are challenging clinical problems. Current reconstructive methods... more Large segmental osseous defects are challenging clinical problems. Current reconstructive methods, using non-viable allografts, vascularized autografts or prostheses have significant rates of serious complications and failure. These include infection, stress fracture and non-union (frozen structural allogenic bone); loosening and implant failure (prosthetic replacement); limited availability, poor match of size and shape and donor site morbidity (vascularized autograft bone). In the future, microvascular transplantation of living allogenic or xenogenic bone could solve some of these issues, combining the advantages of living bone autografts (capability of primary osseous healing, remodeling, and fracture resistance) with the ability to match size and shape, provide immediate stability and avoid donor site morbidity. Xenotransplants would be particularly attractive, as they could be readily available, if long-term bone survival could be achieved without unacceptable morbidity. Here, we present a preliminary study to evaluate a new and unique method to maintain xenogenic bone circulation without need for long-term immune modulation that depends upon generation of a neo-angiogenic circulation within the transplanted bone from recipient-derived vessels. Thus, only short-term immunosuppression would be required to achieve bone survival. One hundred and forty-one hamster femora were microsurgically transplanted to rats, restoring nutrient vessel circulation with standard microvascular anastomoses. At the same time, a host-derived arteriovenous bundle (AVB) was placed within the medullary canal. Two independent variables were evaluated: use of tacrolimus/cyclophosmamid immunosuppression (IS) and patency of the implanted AVB. Rats were therefore randomized to four groups; group 1-no IS + patent AVB; group 2-no IS + ligated AVB; group 3-IS + patent AVB; group 4-IS + ligated AVB. Rats were sacrificed after 1 or 2 weeks. We evaluated bone blood flow (microsphere entrapment), neoangiogenesis (microangiography and quantification of capillary density), bone necrosis rate (osteocyte counts) and nutrient pedicle rejection (microsurgical anastomotic patency). Statistical Analysis was performed with two-way ANOVA with Bonferroni adjustment. Differences were considered significant when P < 0.05. Capillary density was significantly increased with a patent intramedullary AVB (groups 1/3) compared to groups with ligated AVBs (groups 3/4). Capillary sprouting was predominantly restricted to the endosteal layer. Most nutrient pedicles (78.7%) stayed patent in groups with IS (groups 3 and 4). Consequently, bone blood flow was significantly higher in groups 3 and 4 compared to groups 1 and 2. Similarly, a patent AV bundle improved flow in group 1 when compared to group 2. The bone necrosis rate was not influenced by the presence of patent AVBs but was significantly reduced in groups 3 and 4. Surgical angiogenesis occurs when patent arteriovenous bundles are placed in the medullary canal of xenogenic bone and leads to increased bone blood flow. Bone viability was not significantly influenced by neoangiogenesis. Although capillary sprouting was restricted to the endosteal layer in this short term study, more complete cortical revascularization might be observed in a long-term study. Such a study should further evaluate whether these new vessels supply sufficient blood flow to maintain long-term bone viability and allow remodeling.
Spastic hemiplegia results from several relatively common disorders, including stroke, traumatic ... more Spastic hemiplegia results from several relatively common disorders, including stroke, traumatic brain injury, and cerebral palsy. Frequently, upper-limb function is impaired. In this issue of the Journal, Zheng et al.1 report a new approach to the treatment of this condition: the use of a contralateral C7 nerve transfer from the nonparalyzed side to the paralyzed side in order to engage the unimpaired cerebral hemisphere. Nerve transfers have long been performed as treatment for lesions affecting the lower motor neurons, mostly involving the brachial plexus. Gu and colleagues at Huashan Hospital, Fudan University, in Shanghai have pioneered nerve transfers, particularly those . . .
Reconstruction after pan-plexus root avulsions often includes gracilis free functioning muscle tr... more Reconstruction after pan-plexus root avulsions often includes gracilis free functioning muscle transfer. For elbow flexion reconstruction, the free functioning muscle transfer distal tendon is inserted into the biceps tendon or more distally (i.e., flexor digitorum profundus/flexor pollicis longus tendons) for combined elbow and finger flexion; the theoretical drawback of the latter approach is weaker elbow flexion. The authors compared elbow flexion strength with a biceps tendon versus a flexor digitorum profundus/flexor pollicis longus tendon attachment to determine which insertion point resulted in better elbow flexion. Thirty-nine patients underwent free functioning muscle transfer with either a biceps tendon or a distal attachment. Groups were compared on postoperative elbow flexion strength, preoperative and postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire scores, range of motion, and other surgical and demographic characteristics. A biomechanical analys...
The aim of this study is to quantify the length of the axillary nerve (AN) that is able to be dis... more The aim of this study is to quantify the length of the axillary nerve (AN) that is able to be dissected through a standard anterior (deltopectoral) and posterior approach. We hypothesize that a segment of the AN cannot be reached using both approaches simultaneously. ANs of 5 frozen cadavers were dissected using an anterior and posterior approach. A first surgical clip marked the most visible distal part of the nerve from the deltopectoral approach; a second surgical clip marked the most proximal part from the posterior approach. The two surgical clips were localized with a shoulder radiograph. We performed measurements of the different AN segments. In all specimens there were three zones of the AN. Zone A (anterior): nerve segment from the origin of the AN to the first surgical clip, located at the level of the triangle formed by the subscapularis muscle (medial), conjoined tendon (lateral) and axillary fat (inferior). Zone B (blind - nerve segment not reachable through both approa...
After complete five-level root brachial plexus injury, free functional muscle transfer and interc... more After complete five-level root brachial plexus injury, free functional muscle transfer and intercostal nerve transfer to the musculocutaneous nerve are two potential reconstructive options for elbow flexion. The aim of this study was to determine the outcomes of free functional muscle transfer versus intercostal nerve-to-musculocutaneous nerve transfers with respect to strength. Sixty-two patients who underwent free functional muscle transfer reconstruction or intercostal nerve-to-musculocutaneous nerve transfer for elbow flexion following a pan-plexus injury were included. The two groups were compared with respect to postoperative elbow flexion strength according to the British Medical Research Council grading system; preoperative and postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire scores. In the free functional muscle transfer group, 67.7 percent of patients achieved M3 or M4 elbow flexion. In the intercostal nerve-to-musculocutaneous nerve transfer group, ...
Isometric tetanic muscle force has been described in a rat model to evaluate motor recovery in a ... more Isometric tetanic muscle force has been described in a rat model to evaluate motor recovery in a segmental sciatic nerve defect reconstructions. However, to test longer nerve defects, an alternative and larger animal model is necessary. The purpose of this study is to describe and validate a technique for isometric force measurement of the tibialis anterior (TA) muscle in New Zealand rabbits. Muscle preload and electrical stimulation parameters were optimized to obtain the highest tetanic contraction bilaterally in 10 animals. Electrophysiology, muscle weight, peroneal nerve length, and histomorphometry were also analyzed. Only the peroneal nerve length and the ratio of highest muscle force/muscle weight demonstrated the equivalence between the sides. A small variability of TA muscle force and TA muscle weight was observed between the sides suggesting dominance. Optimization of electrical stimulation and preload as well as the use of correct anesthesia were fundamental to acquire the highest muscle force.
An effective alternative to nerve autograft is needed to minimize morbidity and solve limited-ava... more An effective alternative to nerve autograft is needed to minimize morbidity and solve limited-availability issues. We hypothesized that the use of processed allografts and collagen conduits would allow recovery of motor function that is equivalent to that seen after the use of autografts. Sixty-five Lewis rats were divided into three experimental groups. In each group, a unilateral 10-mm sciatic nerve defect was repaired with nerve autograft, allograft treated by AxoGen Laboratories, or a 2.0-mm-inner-diameter collagen conduit. The animals were studied at twelve and sixteen weeks postoperatively. Evaluation included bilateral measurement of the tibialis anterior muscle force and muscle weight, electrophysiology, assessment of ankle contracture, and peroneal nerve histomorphometry. Muscle force was measured with use of our previously described and validated method. Results were expressed as a percentage of the values on the contralateral side. Two-way analysis of variance (ANOVA) corrected by the Ryan-Einot-Gabriel-Welsch multiple range test was used for statistical investigation (α = 0.05). At twelve weeks, the mean muscle force (and standard deviation), as compared with that on the contralateral (control) side, was 45.2% ± 15.0% in the autograft group, 43.4% ± 18.0% in the allograft group, and 7.0% ± 9.2% in the collagen group. After sixteen weeks, the recovered muscle force was 65.5% ± 14.1% in the autograft group, 36.3% ± 15.7% in the allograft group, and 12.1% ± 16.0% in the collagen group. Autograft was statistically superior to allograft and the collagen conduit at sixteen weeks with regard to all parameters except histomorphometric characteristics (p < 0.05). The collagen-group results were inferior. All autograft-group outcomes improved from twelve to sixteen weeks, with the increase in muscle force being significant. The use of autograft resulted in better motor recovery than did the use of allograft or a collagen conduit for a short nerve gap in rats. A longer evaluation time of sixteen weeks after segmental nerve injuries in rats would be beneficial as more substantial muscle recovery was seen at that time.
Large segmental osseous defects are challenging clinical problems. Current reconstructive methods... more Large segmental osseous defects are challenging clinical problems. Current reconstructive methods, using non-viable allografts, vascularized autografts or prostheses have significant rates of serious complications and failure. These include infection, stress fracture and non-union (frozen structural allogenic bone); loosening and implant failure (prosthetic replacement); limited availability, poor match of size and shape and donor site morbidity (vascularized autograft bone). In the future, microvascular transplantation of living allogenic or xenogenic bone could solve some of these issues, combining the advantages of living bone autografts (capability of primary osseous healing, remodeling, and fracture resistance) with the ability to match size and shape, provide immediate stability and avoid donor site morbidity. Xenotransplants would be particularly attractive, as they could be readily available, if long-term bone survival could be achieved without unacceptable morbidity. Here, we present a preliminary study to evaluate a new and unique method to maintain xenogenic bone circulation without need for long-term immune modulation that depends upon generation of a neo-angiogenic circulation within the transplanted bone from recipient-derived vessels. Thus, only short-term immunosuppression would be required to achieve bone survival. One hundred and forty-one hamster femora were microsurgically transplanted to rats, restoring nutrient vessel circulation with standard microvascular anastomoses. At the same time, a host-derived arteriovenous bundle (AVB) was placed within the medullary canal. Two independent variables were evaluated: use of tacrolimus/cyclophosmamid immunosuppression (IS) and patency of the implanted AVB. Rats were therefore randomized to four groups; group 1-no IS + patent AVB; group 2-no IS + ligated AVB; group 3-IS + patent AVB; group 4-IS + ligated AVB. Rats were sacrificed after 1 or 2 weeks. We evaluated bone blood flow (microsphere entrapment), neoangiogenesis (microangiography and quantification of capillary density), bone necrosis rate (osteocyte counts) and nutrient pedicle rejection (microsurgical anastomotic patency). Statistical Analysis was performed with two-way ANOVA with Bonferroni adjustment. Differences were considered significant when P < 0.05. Capillary density was significantly increased with a patent intramedullary AVB (groups 1/3) compared to groups with ligated AVBs (groups 3/4). Capillary sprouting was predominantly restricted to the endosteal layer. Most nutrient pedicles (78.7%) stayed patent in groups with IS (groups 3 and 4). Consequently, bone blood flow was significantly higher in groups 3 and 4 compared to groups 1 and 2. Similarly, a patent AV bundle improved flow in group 1 when compared to group 2. The bone necrosis rate was not influenced by the presence of patent AVBs but was significantly reduced in groups 3 and 4. Surgical angiogenesis occurs when patent arteriovenous bundles are placed in the medullary canal of xenogenic bone and leads to increased bone blood flow. Bone viability was not significantly influenced by neoangiogenesis. Although capillary sprouting was restricted to the endosteal layer in this short term study, more complete cortical revascularization might be observed in a long-term study. Such a study should further evaluate whether these new vessels supply sufficient blood flow to maintain long-term bone viability and allow remodeling.
Spastic hemiplegia results from several relatively common disorders, including stroke, traumatic ... more Spastic hemiplegia results from several relatively common disorders, including stroke, traumatic brain injury, and cerebral palsy. Frequently, upper-limb function is impaired. In this issue of the Journal, Zheng et al.1 report a new approach to the treatment of this condition: the use of a contralateral C7 nerve transfer from the nonparalyzed side to the paralyzed side in order to engage the unimpaired cerebral hemisphere. Nerve transfers have long been performed as treatment for lesions affecting the lower motor neurons, mostly involving the brachial plexus. Gu and colleagues at Huashan Hospital, Fudan University, in Shanghai have pioneered nerve transfers, particularly those . . .
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