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1.
Artigo em Inglês | MEDLINE | ID: mdl-32418840

RESUMO

BACKGROUND: When direct nerve coaptation is impossible after peripheral nerve injury, autografts, processed allografts, or conduits are used to bridge the nerve gap. The purpose of this study was to examine if human adipose-derived Mesenchymal Stromal/Stem Cells (MSCs) could be introduced to commercially available nerve graft substitutes and to determine cell distribution and the seeding efficiency of a dynamic seeding strategy. METHODS: MTS assays examined the viability of human MSCs after introduction to the AvanceⓇ Nerve Graft and the NeuraGenⓇ Nerve Guide. MSCs were dynamically seeded on nerve substitutes for either 6, 12, or 24 h. Cell counts, live/dead stains, Hoechst stains, and Scanning Electron Microscopy (SEM) revealed the seeding efficiency and the distribution of MSCs after seeding. RESULTS: The viability of MSCs was not affected by nerve substitutes. Dynamic seeding led to uniformly distributed MSCs over the surface of both nerve substitutes and revealed MSCs on the inner surface of the NeuraGenⓇ Nerve Guides. The maximal seeding efficiency of NeuraGenⓇ Nerve Guides (94%), obtained after 12 h was significantly higher than that of AvanceⓇ Nerve Grafts (66%) (p = 0.010). CONCLUSION: Human MSCs can be dynamically seeded on AvanceⓇ Nerve Grafts and NeuraGenⓇ Nerve Guides. The optimal seeding duration was 12 h. MSCs were distributed in a uniform fashion on exposed surfaces. This study demonstrates that human MSCs can be effectively and efficiently seeded onto commercially available nerve autograft substitutes in a timely fashion and sets the stage for the clinical application of MSC-seeded nerve graft substitutes clinically.

3.
Gene ; 747: 144627, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32224270

RESUMO

BACKGROUND: Bone allotransplant viability can be maintained long-term by implanting arteriovenous (AV) bundles and creating an autogenous neoangiogenic circulation. Only short-term immunosuppression is required. This study investigates the origin of viable osteocytes observed in areas of active bone remodeling in orthotopically transplanted tibiae in a Yucatan mini-pig model. METHODS: Segmental tibial defects created in female Yucatan minipigs (N = 14) were reconstructed with a matched vascularized composite allotransplant from a male donor. The circulation was microsurgically restored, with simultaneous autogenous AV-bundle implantation in group 1 (N = 7). A ligated AV-bundle was implanted as a no-angiogenesis control in group 2 (N = 7). After 20-weeks, repopulation of the allotransplant was assessed by real-time qPCR measurement of relative copy numbers of a Y chromosome-specific gene (SRY) and an autosomal housekeeping gene, ribosomal protein L4 (RPL4). A lower SRY/RPL4 ratio demonstrates replacement of male allogeneic cells with female, autogenous cells in the sample. Genomic DNA was extracted from cross-sections of the allotransplant, liver and spleen. Additionally, areas of new bone formation within the allotransplant were sampled by laser capture microdissection. A comparison was made between groups as well as male control samples. RNA was extracted from bone as well, as a measure of metabolically active cells. RESULTS: Laser-captured areas of new bone formation in animals with both normal and ligated AV-bundles were found to have significantly lower relative copy numbers of SRY (p = 0.03) than control specimens from male bone, indicating replacement by female (autogenous) bone-forming cells. Analysis of an entire segment of the allotransplant from Group 1 was similarly reduced (p = 0.04), unlike that from Group 2. RNA expression of SRY was observed in both groups. No chimerism could be found in non-bone tissues (liver and spleen). CONCLUSION: We observed a significant level of transplant chimerism in areas of new bone formation sampled by laser capture microdissection. The migration of autogenous cells including osteocytes was seen in both groups. Survival of some allogeneic (male) cells was also demonstrable. No microchimerism was found in liver and spleen.


Assuntos
Transplante Ósseo , Quimerismo , Neovascularização Fisiológica , Animais , DNA/genética , Feminino , Fígado/metabolismo , Masculino , Osteogênese , RNA/genética , RNA/metabolismo , Baço/metabolismo , Suínos , Transplante Homólogo
4.
Microsurgery ; 2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32233045

RESUMO

PURPOSE: Adipose derived mesenchymal stem cells (MSCs) are hypothesized to supplement tissues with growth factors essential for regeneration and neovascularization. The purpose of this study was to determine the effect of MSCs with respect to neoangiogenesis when seeded onto a decellularized nerve allograft in a rat sciatic nerve defect model. METHODS: Allograft nerves were harvested from Sprague-Dawley rats and decellularized. MSCs were obtained from Lewis rats. 10 mm sciatic nerve defects in Lewis rats were reconstructed with reversed autograft nerves, decellularized allografts, decellularized allografts seeded with undifferentiated MSC or decellularized allografts seeded with differentiated MSCs. At 16 weeks, the vascular surface area and volume were evaluated. RESULTS: The vascular surface area in normal nerves (34.9 ± 5.7%), autografts (29.5 ± 8.7%), allografts seeded with differentiated (38.9 ± 7.0%) and undifferentiated MSCs (29.2 ± 3.4%) did not significantly differ from each other. Unseeded allografts (21.2 ± 6.2%) had a significantly lower vascular surface area percentage than normal nonoperated nerves (13.7%, p = .001) and allografts seeded with differentiated MSCs (17.8%, p = .001). Although the vascular surface area was significantly correlated to the vascular volume (r = .416; p = .008), no significant differences were found between groups concerning vascular volumes. The vascularization pattern in allografts seeded with MSCs consisted of an extensive nonaligned network of microvessels with a centripetal pattern, while the vessels in autografts and normal nerves were more longitudinally aligned with longitudinal inosculation patterns. CONCLUSIONS: Neoangiogenesis of decellularized allograft nerves was enhanced by stem cell seeding, in particular by differentiated MSCs. The pattern of vascularization was different between decellularized allograft nerves seeded with MSCs compared to autograft nerves.

5.
Artigo em Inglês | MEDLINE | ID: mdl-32187174

RESUMO

Management of hand and wrist avascular necrosis with osteochondral fragmentation or focal arthritis can be a challenging problem with a variety procedures described for its treatment. Osteochondral autograft transplantation systems have been utilized in various focal defects of the knee, ankle, elbow, and wrist. The same principle for the treatment of focal defects of the proximal scaphoid, proximal capitate as well as metacarpal head as an alternative treatment is described. The main indication for this treatment is to address focal or partial osteochondral defects where the size of the defect is smaller than the isthmus of the involved bone to accommodate a cylindrical osteochondral graft that can be press fit. Larger and complete defects are contraindications to this treatment. We discuss the surgical technique as well as its main indications and expected outcomes.

6.
Plast Reconstr Surg ; 2020 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-32195864

RESUMO

BACKGROUND: Processed nerve allografts are a promising alternative to nerve autografts providing an unlimited readily available supply while avoiding donor site morbidity and the need for immunosuppression. Currently, clinically available nerve allografts do not provide satisfactory results for motor reconstruction. This study evaluated motor recovery after reconstruction of a long nerve gap using a processed nerve allograft. Furthermore, the influence of storage techniques was evaluated. METHODS: Nerve allografts were decellularized using elastase and detergents and stored at either 4 or -80°C. In 36 New Zealand White rabbits, a 3-cm peroneal nerve gap was repaired with either an autograft (group 1, control) or cold- (group 2) or frozen-stored (group 3) processed nerve allograft. Nerve recovery was evaluated using various measurements including longitudinal ultrasound measurements, electrophysiology (CMAP), isometric tetanic force (ITF), wet muscle weight (MW) and histomorphometry after 24 weeks. RESULTS: Longitudinal ultrasound measurements showed that the cold-stored allograft provided earlier regeneration than the frozen-stored allograft. Ultrasound furthermore showed significantly inferior recovery in group 3 than in both other groups(p<0.05). MW and ITF showed similar outcomes in the autograft and cold-stored allograft groups(p=0.096 (MW) and p=0.286(ITF)). MW and ITF confirmed inferiority of the frozen-stored allograft to the autograft(p<0.01 (MW) and p=0.02(ITF)). CONCLUSIONS: Freeze-storage of the nerve allograft significantly impairs functional recovery and should be avoided. The cold-stored optimized nerve allograft yields functional recovery similar to the gold standard autograft in the reconstruction of a 3-cm motor nerve defect. Future studies should focus on further improvement of the nerve allograft.

7.
Artigo em Inglês | MEDLINE | ID: mdl-32059943

RESUMO

While surgical management of cubital tunnel syndrome (CuTS) results in the improvement of pain, paresthesia and restoration of motor function, there is a subset of patients who do not improve after primary surgery and require revision. The purpose of this study was to evaluate the incidence and risk factors for revision after primary CuTS. A retrospective review of patients who underwent revision CuTS after unsuccessful primary surgery from February 1989 to May 2009 was performed. Data regarding patients' demographics, age at primary and revision surgeries, handedness, presenting symptoms and the duration, physical examination, McGowan grading, electrodiagnostic findings and final outcomes were collected. A total of 1239 patients undergoing 1279 cubital tunnel surgeries were identified; of which 17 patients who underwent 18 revision CuTS met our inclusion criteria. Forty-one randomly selected consecutive patients who underwent primary CuTS (control cohort) were compared to identify the risk factors associated with revision CuTS. Younger age at presentation, greater static 2-point discrimination (S2PD) and a history of diabetes were associated with a greater number of revision surgeries. Patients requiring revision for primary CuTS were 8.4 years on average younger, had greater S2PD and were more likely to have diabetes. Pain as a presenting symptom compared to weakness and numbness was also a more common complaint in this cohort of patients. Future larger multicenter prospective studies are recommended.

8.
J Plast Reconstr Aesthet Surg ; 73(3): 460-468, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31928962

RESUMO

INTRODUCTION: The specific patterns of revascularization of allograft nerves after the addition of vascularization remain unknown. The aim of this study was to determine the revascularization patterns of optimized processed allografts (OPA) after surgically induced angiogenesis to the wound bed in a rat sciatic nerve model. MATERIALS AND METHODS: In 51 Lewis rats, sciatic nerve gaps were repaired with (i) autografts, (ii) OPA and (iii) OPA wrapped in a pedicled superficial inferior epigastric artery fascia flap (SIEF) to provide vascularization to the wound bed. At 2, 12, and 16 weeks, the vascular volume and vascular surface area in nerve samples were measured using micro CT and photography. Cross-sectional images were obtained and the number of vessels was quantified in the proximal, mid, and distal sections of the nerve samples. RESULTS: At 2 weeks, the vascular volume of SIEF nerves was comparable to control (P = 0.1). The vascular surface area in SIEF nerves was superior to other groups (P<0.05). At 12 weeks, vascularity in SIEF nerves was significantly higher than allografts (P<0.05) and superior compared to all other groups (P<0.0001) at 16 weeks. SIEF nerves had a significantly increased number of vessels compared to allografts alone in the proximal (P<0.05) and mid-section of the graft (P<0.05). CONCLUSIONS: Addition of surgical angiogenesis to the wound bed greatly improves revascularization. It was demonstrated that revascularization occurs primarily from proximal to distal (proximal inosculation) and not from both ends as previously believed and confirms the theory of centripetal revascularization.

9.
Microsurgery ; 40(2): 183-188, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31246325

RESUMO

PURPOSE: Animal models can be helpful in evaluating new surgical strategies for brachial plexus reconstruction. While several groups have already used the rabbit brachial plexus to model injury, reports conflict in anatomic detail and do not identify a nerve-muscle pair to measure motor function recovery after reconstruction. The purpose of the current study is to describe the innervations of the biceps and triceps muscles in rabbits, which are both amenable to study in brachial plexus injury models. MATERIALS AND METHODS: Thirteen rabbits weighing 2-2.5 kg were anesthetized. Six rabbits were sacrificed and dissected using loupe and microscope magnification to understand the overall morphology of the brachial plexus. Seven rabbits underwent electrophysiologic investigation. A bipolar nerve stimulator was used to systematically stimulate the roots, trunks and divisions, and nerve branches of the rabbit brachial plexus and compound muscle action potential was used to record muscle response. Nerve length and width measurements were not recorded. RESULTS: Roots contributing to the brachial plexus were C5, C6, C7, C8, and T1. In contrast to other anatomical studies, T2 did not contribute to the brachial plexus. The triceps was innervated by the radial nerve, which received contributions from C6 (1.6 mA), C7 (1.9 mA), C8, and T1 (12.2 mA).The biceps had dual innervation (proximally and distally). The proximal branch received contributions from C6 (3.5 mA) and C7 (5mA). The distal portion was innervated by a branch from the median nerve, which received innervation from C6, C7, C8, and T1. CONCLUSIONS: The overall structure of rabbit brachial plexus is described and innervation of the biceps and triceps is described in detail. This anatomic investigation will form the basis of a future brachial plexus model of injury and repair.

10.
J Orthop Res ; 38(2): 288-296, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31579953

RESUMO

Vascularized composite allotransplantation of bone is a possible alternative treatment for large osseous defects but requires life-long immunosuppression. Surgical induction of autogenous neo-angiogenic circulation maintains transplant viability without this requirement, providing encouraging results in small animal models [1-3]. A preliminary feasibility study in a swine tibia model demonstrated similar findings [4, 5]. This study in swine tibial allotransplantation tests its applicability in a pre-clinical large animal model. Previously, we have demonstrated bone vascularized composite allotransplantation (VCA) survival was not the result of induction of tolerance nor an incompetent immune system [1]. Fourteen tibia vascularized bone allotransplants were microsurgically transplanted orthotopically to reconstruct size-matched tibial defects in Yucatan miniature swine. Two weeks of immunosuppression was used to maintain allotransplant pedicle patency during angiogenesis from a simultaneously implanted autogenous arteriovenous bundle. The implanted arteriovenous bundle was patent in group 1 and ligated in group 2 (a neo-angiogenesis control). At twenty weeks, we quantified the neo-angiogenesis and correlated it with transplant viability, bone remodeling, and gene expression. All patent arteriovenous bundles maintained patency throughout the survival period. Micro-angiographic, osteocyte cell count and bone remodeling parameters were significantly higher than controls due to the formation of a neo-angiogenic autogenous circulation. Analysis of gene expression found maintained osteoblastic and osteoclastic activity as well as a significant increase in expression of endothelial growth factor-like 6 (EGFL-6) in the patent arteriovenous bundle group. Vascularized composite allotransplants of swine tibia maintained viability and actively remodeled over 20 weeks when short-term immunosuppression is combined with simultaneous autogenous neo-angiogenesis. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:288-296, 2020.

11.
J Reconstr Microsurg ; 36(2): 82-92, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31470456

RESUMO

BACKGROUND: Bone vascularized composite allotransplantation (VCA) is a possible alternative for the treatment of large bone defects. Clinical application of VCAs is limited by the need for life-long immunosuppression (IS). We report an alternative method to maintain bone allotransplant viability in a large animal model without the need for life-long IS by using autogenous vessel implantation. METHODS: Fourteen bone only VCAs were transplanted in a porcine tibia defect model with short-term IS. Two groups were used to evaluate the effect of the implantation of an autogenous arteriovenous (AV)-bundle, therefore the only difference between the groups was the patency of the AV-bundle. We radiographically evaluated bone healing and allogenic pedicle patency. AV-bundle patency and union were evaluated with micro-CT. Bone remodeling was assessed with histomorphometry and material properties were evaluated with axial compression testing and cyclic reference point indentation. RESULTS: Two subjects did not reach the final time point. Twelve tibiae healed proximally, and nine at the distal transplant-bone interface. Bone allotransplants showed their viability in the first 4 to 6 weeks by significant periosteal bridging arising from the transplant and maintained pedicle patency. Bone material properties were not affected by the implantation of an AV-bundle when compared with ligated AV-bundle controls, but diminished compared with normal bone. Significantly higher bone formation rates resulted from the implantation of a patent AV-bundle. CONCLUSION: New periosteal bone formation and subsequent bone healing result from blood flow through the microsurgically repaired nutrient blood supply, demonstrated by maintained allogenic pedicle patency. The implantation of a patent autogenous AV-bundle has no adverse effect on material properties, but a positive effect on bone remodeling of endosteal surfaces despite thrombosis of the allogenic pedicle. Bone material properties change after transplantation compared with normal bone, although 20-weeks survival time is relatively short for the final evaluation of bone material properties.

12.
J Hand Surg Am ; 45(2): 155.e1-155.e8, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31221517

RESUMO

PURPOSE: To report the clinical outcomes and describe the surgical technique of triceps muscle reinnervation using 2 different distal nerve transfers: the flexor carpi ulnaris (FCU) fascicle of the ulnar nerve and the posterior branch of the axillary nerve (PBAN) to the triceps nerve branch. METHODS: A retrospective review of patients undergoing FCU fascicle of ulnar nerve or PBAN to triceps nerve branch transfer was performed. Outcome measures included preoperative and postoperative modified British Medical Research Council (MRC) score, EMG results, and complications. RESULTS: Between September 2003 and April 2017, 6 patients were identified. Four patients with a traumatic upper trunk and posterior cord palsy underwent ulnar nerve fascicle to triceps nerve transfer. Two patients with a recovering upper trunk following a pan-brachial plexus palsy underwent PBAN to triceps nerve branch transfer. The median age was 30.0 years (range, 18-68 years). Surgery was performed at a median of 6.9 months (range, 5.0-8.9 months) postinjury, with a median follow-up of 18.4 months (range, 7.6-176.3) months. Before surgery, 4 patients exhibited grade M0 and 2 patients exhibited grade M1 triceps strength. Four patients had M5 donor muscle strength and 2 had grade M4. Postoperatively, 4 patients regained MRC grade M4 triceps muscle strength, 1 regained M3, and 1 regained M2. There was no noticeable donor muscle weakness. CONCLUSIONS: Nerve fascicles to the FCU and PBAN are viable options for obtaining meaningful triceps muscle recovery in a select group of patients. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

13.
J Plast Reconstr Aesthet Surg ; 73(1): 81-89, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31202698

RESUMO

BACKGROUND: Although undifferentiated MSCs and MSCs differentiated into Schwann-like cells have been extensively compared in vitro and in vivo, studies on the ability and efficiency of differentiated MSCs for delivery into nerve allografts are lacking. As this is essential for their clinical potential, the purpose of this study was to determine the ability of MSCs differentiated into Schwann-like cells to be dynamically seeded on decellularized nerve allografts and to compare their seeding potential to that of undifferentiated MSCs. METHODS: Fifty-six sciatic nerve segments from Sprague Dawley rats were decellularized, and MSCs were harvested from Lewis rat adipose tissue. Control and differentiated MSCs were dynamically seeded on the surface of decellularized allografts. Cell viability, seeding efficiencies, cell adhesion, distribution, and migration were evaluated. RESULTS: The viability of both cell types was not influenced by the processed nerve allograft. Both cell types achieved maximal seeding efficiency after 12 h of dynamic seeding, albeit that differentiated MSCs had a significantly higher mean seeding efficiency than control MSCs. Dynamic seeding resulted in a uniform distribution of cells among the surface of the nerve allograft. No cells were located inside the nerve allograft after seeding. CONCLUSION: Differentiated MSCs can be dynamically seeded on the surface of a processed nerve allograft, in a similar fashion as undifferentiated MSCs. Schwann-like differentiated MSCs have a significantly higher seeding efficiency after 12 h of dynamic seeding. We conclude that differentiation of MSCs into Schwann-like cells may improve the seeding strategy and the ability of nerve allografts to support axon regeneration.

14.
Gene ; 724: 144151, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31626959

RESUMO

BACKGROUND: Differentiation of mesenchymal stem cells (MSCs) into Schwann-like cells onto processed nerve allografts may support peripheral nerve repair. The purpose of this study was to understand the biological characteristics of undifferentiated and differentiated MSCs before and after seeding onto a processed nerve allograft by comparing gene expression profiles. METHODS: MSCs from Lewis rats were cultured in maintenance media or differentiated into Schwann-like cells. Both treatment groups were dynamically seeded onto decellularized nerve allografts derived from Sprague-Dawley rats. Gene expression was quantified by quantitative polymerase chain reaction (qPCR) analysis of representative biomarkers, including neurotrophic (GDNF, PTN, GAP43, PMP22), angiogenic (CD31, VEGF1), extracellular matrix (ECM) (COL1A1, COL3A1, FBLN1, LAMB2) or cell cycle (CAPS3, CCBN2) genes. Gene expression values were statistically evaluated using a 2-factor ANOVA with repeated measures. RESULTS: Baseline gene expression of undifferentiated and differentiated MSCs was significantly altered upon interaction with processed nerve allografts. Interaction between processed allografts and undifferentiated MSCs enhanced expression of neurotrophic (NGF, GDNF, PMP22), ECM (FBLN1, LAMB2) and regulatory cell cycle genes (CCNB2) during a 7-day time course. Interactions of differentiated MSCs with nerve allografts enhanced expression of neurotrophic (NGF, GDNF, GAP43), angiogenic (VEGF1), ECM (FBLN1) and regulatory cell cycle genes (CASP3, CCNB2) within one week. CONCLUSIONS: Dynamic seeding onto processed nerve allografts modulates temporal gene expression profiles of differentiated and undifferentiated MSCs. These changes in gene expressions may support the reparative functions of MSCs in supporting nerve regeneration in different stages of axonal growth.


Assuntos
Diferenciação Celular/genética , Células-Tronco Mesenquimais/citologia , Nervo Isquiático/transplante , Transcriptoma , Tecido Adiposo/citologia , Aloenxertos , Animais , Técnicas de Cultura de Células/métodos , Matriz Extracelular/genética , Células-Tronco Mesenquimais/fisiologia , Neovascularização Fisiológica/genética , Regeneração Nervosa , Ratos Endogâmicos Lew , Ratos Sprague-Dawley , Células de Schwann/citologia , Nervo Isquiático/citologia , Fatores de Tempo , Transplante Homólogo
15.
World Neurosurg ; 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31837496

RESUMO

OBJECTIVE: To investigate functional outcome from reconstructive surgery in adult traumatic brachial plexus injury (AT-BPI) with associated vascular lesions. METHODS: A retrospective review was performed of 325 patients with AT-BPI who underwent reconstructive surgery between 2001 and 2012. Patients with (vascular group) and without (control group) vascular injuries were identified by review of medical documentation. Patient presentation, characteristics of nerve and associated lesions, and surgical management were evaluated to identify prognostic variables. Postoperative muscle strength, range of motion, and patient-reported disability scores were analyzed to determine long-term outcome. RESULTS: Sixty-eight patients had a concomitant vascular injury. There were no significant differences in age or sex between the control and vascular groups. The vascular group was more likely to have pan-plexus lesions (P < 0.0001), with significantly more associated upper extremity injuries (P < 0.0001). The control group underwent more nerve transfers, whereas the vascular group underwent more nerve grafting (P = 0.003). Complete outcome data were obtained in 139 patients, which included 111 control (43% of all control subjects) and 28 vascular patients (41%). There was no significant difference in patient-reported disability scores between the 2 groups. However, 73% of control subjects had grade 3 or greater postoperative elbow flexion, whereas only 43% of vascular patients achieved this strength (P = 0.003). Control patients demonstrated a greater increase in strength of shoulder abduction as well (P = 0.004). Shoulder external rotation strength was grade 0 in most patients, with no difference between the 2 groups. CONCLUSIONS: Concomitant vascular injury leads to worse functional outcome after reconstructive surgery of traumatic brachial plexus injury.

16.
Microsurgery ; 2019 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-31758730

RESUMO

INTRODUCTION: Nerve regeneration involves multiple processes, which enhance blood supply that can be promoted by growth factors. Currently, tools are lacking to visualize the vascularization patterns in transplanted nerves in vivo. The purpose of this study was to describe three-dimensional visualization of the vascular system in the rat sciatic nerve and to quantify angiogenesis of nerve reconstruction. MATERIALS AND METHODS: In 12 Lewis rats (weighing 250-300 g), 10 mm sciatic nerve gaps were repaired with ipsilateral reversed autologous nerve grafts. At 12 and 16 weeks of sacrifice, Microfil® contrast compound was injected in the aorta. Nerve autografts (N = 12) and contralateral untreated nerves (N = 12) were harvested and cleared while preserving the vasculature. The amount of vascularization was measured by quantifying the vascular surface area using conventional photography (two-dimensional) and the vascular volume was calculated with microcomputed tomography (three-dimensional). For each measurement, a vessel/nerve area ratio was calculated and expressed in percentages (vessel%). RESULTS: The vascular volume measured 3.53 ± 0.43% in autografts and 4.83 ± 0.45% vessels in controls at 12 weeks and 4.95 ± 0.44% and 6.19 ± 0.29% vessels at 16 weeks, respectively. The vascular surface area measured 25.04 ± 2.77% in autografts and 26.87 ± 2.13% vessels in controls at 12 weeks, and 28.11 ± 3.47% and 33.71 ± 2.60% vessels at 16 weeks, respectively. The correlation between both methods was statistically significant (p = .049). CONCLUSIONS: Both methods are considered to successfully reflect the degree of vascularization. Application of this technique could be used to visualize and objectively quantify angiogenesis of the transplanted nerve graft. Moreover, this simple method is easily reproducible and could be extrapolated to any other desired target organ ex vivo in small animals to investigate the vascular network.

17.
Microsurgery ; 39(7): 634-641, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31386247

RESUMO

INTRODUCTION: There is conflicting anatomic and innervation data regarding the rabbit brachial plexus injury model. This study aims to validate a rabbit brachial plexus injury model. We hypothesize the middle trunk (C6, C7) is the primary innervation of the biceps, and when cut and unrepaired, would demonstrate lack of recovery and when repaired would demonstrate evidence of recovery. MATERIALS AND METHODS: Twenty two male New Zealand white rabbits (3-4 kg) underwent unilateral surgical division of the middle trunk. Five rabbits were randomly assigned to the "no-repair" group while the remaining 17 rabbits underwent direct coaptation ("repair" group). Rabbits were followed for 12 weeks, with ultrasound measurement of biceps cross-sectional area performed preoperatively, and at 4, 8, and 12 weeks postoperatively. At a euthanasia procedure, bilateral compound muscle action potential (CMAP) and isometric tetanic force (ITF) were measured. Bilateral biceps muscles were harvested and wet muscle weight was recorded. The operative side was expressed as a percentage of the non-operated side, and differences between the no repair and repair rabbits were statistically compared. RESULTS: The repair group demonstrated significantly higher CMA (23.3 vs. 0%, p < .05), ITF (25.6 vs. 0%, p < .05), and wet muscle weight (65.8 vs. 52.0%, p < .05) as compared to the unrepaired group. At 4 weeks postoperatively, ultrasound-measured cross-sectional area of the biceps demonstrated atrophy in both groups. At 12 weeks, the repair group had a significantly larger cross-sectional area as compared to the no-repair group (89.1 vs. 59.3%, p < .05). CONCLUSIONS: This injury model demonstrated recovery with repair and lack of function without repair. Longer survival time is recommended for future investigations.

18.
J Plast Reconstr Aesthet Surg ; 72(9): 1503-1508, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31253460

RESUMO

The arterial anatomy of the medial femoral condyle (MFC) for vascularized bone grafting has been extensively studied in cadaveric specimens. A majority of cadaveric studies have limited numbers of specimens, and the data from these studies are extrapolated to the surgical environment. The purpose of this study is to evaluate the vascular anatomy of the medial femoral condyle in a large clinical series. A retrospective review of operative reports was conducted of medial femoral condyle and trochlea vascularized bone grafts performed by the senior surgeons between 2005 and 2018. A total of 113 patients were included in the study. Demographic data, preoperative diagnosis, and type of graft harvested were collected. The descending genicular artery, a branch of the superficial femoral artery, was the dominant pedicle in 77% of cases. It was also the dominant arterial pedicle for medial femoral trochlea (MFT) bone grafts in 7 out of the 9 cases (77.8%). The superomedial genicular artery was the dominant pedicle in 23% (26 of 113 total) of all cases. In eight patients, a descending genicular branch was not identified. The superomedial genicular artery was absent in 2% of cases (2 of 113). The descending genicular artery was the dominant arterial pedicle for vascularized bone grafts from the medial femur and was present in 93% of cases. This is in contrast to published cadaveric studies showing the artery was present in 89% of specimens.

19.
J Orthop Res ; 37(8): 1698-1708, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31042307

RESUMO

Cryopreserved bone allografts (CBA) used to reconstruct segmental bone defects provide immediate structural stability, but are vulnerable to infection, non-union and late stress fracture as the majority of the allograft remains largely avascular. We sought to improve the bone vascularity and bone formation of CBAs by surgical angiogenesis with an implanted arteriovenous (AV) bundle, using a porcine tibial defect model. Cryopreserved tibial bone allografts were transplanted in swine leukocyte antigen (SLA) mismatched Yucatan minipigs to reconstruct a 3.5 cm segmental tibial defect. A cranial tibial AV-bundle was placed within its intramedullary canal to induce angiogenesis. The AV bundle was patent in eight pigs and ligated in a control group of eight pigs. At 20 weeks neo-angiogenesis was evaluated by micro-angiography. Bone formation was measured by quantitative histomorphometry and micro-computed tomography. Seven of eight AV-bundles in the revascularized group were patent. One had thrombosed due to allograft displacement. Total vascular volume was higher in the revascularized allografts compared to the ligated group (p = 0.015). Revascularized allografts had increased levels of bone formation on the allograft endosteal surface compared to the ligated control group (p = 0.05). Surgical angiogenesis of porcine tibial CBAs by intramedullary implantation of an AV-bundle creates an enhanced autogenous neoangiogenic circulation and accelerates active bone formation on allograft endosteal surfaces. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1698-1708, 2019.

20.
J Hand Surg Eur Vol ; 44(9): 913-919, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31117864

RESUMO

We sought to identify predictors of failed ulnar nerve fascicle (to flexor carpi ulnaris) to biceps motor branch transfer. A retrospective review of adult brachial plexus patients treated with flexor carpi ulnaris to biceps transfer with a minimum 1-year follow-up was performed. Failure, defined as modified British Medical Research Council grade <3 elbow flexion was compared with randomly selected controls (M ≥ 4-). Ninety-one patients, of which 80% regained >M3 flexion met criteria. Eighteen failures and 18 controls, with similar follow-up (20 vs 23 months) were evaluated. Preoperative flexor carpi ulnaris weakness (M < 5) was significantly more common in failures (78% vs 33%). The rate of flexor carpi ulnaris recovery after operation was significantly higher in controls (86% vs 7%). Increased failure risk can be expected with impaired preoperative flexor carpi ulnaris function. The challenge is how to identify which patients will regain near normal flexor carpi ulnaris strength as excellent outcomes can be obtained. Level of evidence: III.

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