Anatomic Relationship of the Femoral Neurovascular Bundle in Patients With Congenital Femoral Deficiency.

BACKGROUND: Congenital femoral deficiency (CFD) is a rare condition that affects the morphology of the hip and surrounding soft tissues. Bony deformity and distorted muscular anatomy are well known, but no studies have described the relationship of the femoral neurovascular (NV) bundle to surgically relevant anatomic landmarks. The authors compared the location of the femoral NV bundle on the affected side in patients with CFD with the unaffected side. The authors hypothesized that the bundle on the pathologic side would be in an abnormal position relative to the unaffected side. METHODS: Thirty-three patients diagnosed with unilateral CFD who had undergone preoperative magnetic resonance imaging of the pelvis were included in our study. The authors identified the femoral NV bundle on the axial cuts and measured its distance from the anterior superior iliac spine (ASIS), anterior inferior iliac spine (AIIS), and lesser trochanter (LT). Anatomic percent change and absolute measurements were then compared and correlated with associated boney deformities and the Paley classification. RESULTS: The distance from the femoral NV bundle to the ASIS, AIIS, and LT was significantly different compared with the unaffected side. The AIIS absolute distance and AIIS percent change significantly correlated with the neck-shaft angle of the proximal femur. CONCLUSIONS: In patients with CFD, the femoral NV bundle seems to be further from the LT and closer to the AIIS on the affected side when compared with the unaffected side. magnetic resonance imaging may be helpful to understand the course of the femoral NV bundle before reconstruction in patients with CFD; however, the authors recommend identification of the femoral NV bundle before transection of the proximal rectus femoris tendon to provide safe surgical care. LEVEL OF EVIDENCE: Level IV-case-control study of diagnostic studies.

Neurotization of femoral nerve using the anterior branch of the obturator nerve

Nerve transfer is nowadays a standard procedure for motor reinnervation. There is a vast number of articles in the literature which describe different techniques of neurotization performed after brachial plexus injuries. Although lower limb nerve transfers have also been studied, the number of articles are much limited. The sacrifice of a donor nerve to reinnervate a disrupted one causes morbidity of whichever structures that healthy nerve innervated before the transfer. New studies are focused on isolating branches or fascicles of the main donor trunk that can also be useful for rein-nervation in order to limit donor site motor dysfuntion. Femoral nerve injury due to trauma or surgery cause loss of function of the iliopsoas and quadriceps muscles, which impairs normal gait. In this article we present two clinical cases of femoral nerve injury that were successfully treated with the anterior branch of the obturator nerve

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Investigation of genicular neurotomy of the knee: MRI characterization of anatomy and implications for intervention.

BACKGROUND: Genicular nerve block and subsequent radiofrequency neurotomy (RFN) has emerged as a novel intervention and alternative for total knee arthroplasty in patients with refractory pain from knee osteoarthritis (OA). To our knowledge, there is no cited report correlating the accuracy of localizing the genicular nerves using bony landmarks on magnetic resonance imaging (MRI). OBJECTIVES: To quantify the proximity of superomedial genicular nerve (SMGN), superolateral genicular nerve (SLGN), and inferomedial genicular nerve (IMGN) from a target point. The target point was an intersection marked by a line parallel to the diaphysis and a separate line parallel to the metaphyseal flare along the cortical surfaces of both the femur and tibia. DESIGN: Retrospective chart review. PATIENTS: A total of 25 de-identified knee MRIs were reviewed. METHODS: The coronal proton density fat suppressed sequence was used for identification and localization of the SLGN, SMGN, and IMGN. The neurovascular bundles were traced from posterior location along their origin as they wrap around the distal diaphysis. The nerve locations were determined by consensus measurements performed by two board-certified radiologists with certificates of added qualification in neuroradiology and interventional radiology. The proximity of each respective genicular nerves was measured by drawing a perpendicular line from each genicular nerve to the height of the target point. All measurements were taken on the mid-coronal view at the point of maximal epiphyseal flare. MAIN OUTCOME MEASUREMENTS: Positive values indicated the location of the neurovascular bundle to be superior to the target point. Negative values indicated the location of the neurovascular bundle to be inferior to the target point. RESULTS: The distance between our target point and the inferior border of SLGN ranged from -3 mm to 6 mm. Twenty-three out of 25 (92%) SLGN lied exactly at or above our target intersection. The distance between our target point and the inferior border of SMGN ranged from -1 mm to 2 mm with twenty-two out of 25 (88%) SMGN lied exactly at or above our target point. The distance between our target point and the superior border of IMGN ranged from 0 mm to 3 mm with all (100%) IMGN lying exactly at or above the target point. CONCLUSION: The intersection of the femoral diaphyseal shaft to a line along the metaphyseal flare and the intersection of the tibial diaphyseal shaft to a line along the medial metaphyseal can be used as a target point to localize the genicular nerves with close proximity.

Localización biométrica de los puntos motores del músculo cuádriceps femoral de individuos brasileños / Biometric localization of the motor points of the femoral quadriceps muscle of Brazilian individuals

El músculo cuadríceps femoral es un músculo que participa principalmente en los movimientos de la rodilla y también en la cadera, pudiendo ser afectado por alteraciones en el trofismo muscular, tras lesiones de estas articulaciones o afecciones en el tono muscular, como la espasticidad, tras lesiones cerebrovasculares. Cada una de sus cabezas está inervada por ramos del nervio femoral. El presente estudio tuvo por objetivo la identificación y medición de la distancia de los puntos motores (Pm) del músculo cuadríceps femoral, en relación a estructuras anatómicas de relevancia clínica. Se utilizaron 30 miembros inferiores de 23 cadáveres formolizados, de individuos brasileños adultos. El estudio fue realizado en la Universidade Estadual de Ciências da Saúde de Alagoas (UNCISAL), Maceió, Brasil. Se realizó la disección por planos en la zona medial, anterior y lateral del muslo, identificando a los ramos del nervio femoral para cada componente, músculos recto femoral (mRf), vasto medial (mVm), vasto intermedio (mVint) y vasto lateral (mVlat), localizando cada uno de los Pm. Las mediciones se realizaron con un cáliper marca Mitutoyo de 0,05 mm de precisión. Los datos obtenidos fueron tratados estadísticamente, utilizando para ello, el software STATA (versión 14.1). El mRf, tuvo un promedio de 2,45 ± 1,39 Pm, estando la gran mayoría de los Pm (63 %), en la zona distal del tercio proximal del muslo; el mVm presentó 4,42 ± 2,74 Pm en promedio, encontrándose el 41 % de ellos en el tercio medio del muslo, zona distal; el mVint tuvo 3,99 ± 2,34 Pm en promedio y el 58 % de ellos, se localizaron en la zona proximal del tercio medio del muslo; el mVlat presentó un promedio de 3,88 ± 2,37 Pm y el 50 % de éstos se encontraron en del tercio proximal del muslo. La localización biométrica de los Pm se informa en resultados. La ubicación biométrica de los Pm, favorecerá el quehacer, tanto clínico como quirúrgico, de la zona anterior del muslo.

The quadriceps femoris muscle is a muscle that participates mainly in the movements of the knee and also in the hip, being able to be affected by alterations in muscle trophism, after injuries of these joints or muscular tone conditions, such as spasticity, after injuries cerebrovascular. Each of its heads is innervated by branches of the femoral nerve. The objective of this study was to identify and measure the distance of the motor points (MP) of the quadriceps femoris muscle, in relation to anatomical structures of clinical relevance. Thirty lower limbs of 23 formolized corpses of adult Brazilian individuals were used. The study was conducted at the State University of Ciências da Saúde de Alagoas (UNCISAL), Maceió, Brazil. The dissection was performed by planes in the medial, anterior and lateral thigh, identifying the femoral nerve branches for each component, rectus femoris muscles (Rfm), medial vastus (mVm), vastus intermedius (intVm) and vastus lateralis ( latVm), locating each of the MP. The measurements were made with a Mitutoyo caliper of 0.05 mm accuracy. The data obtained were treated statistically, using the STATA software (version 14.1). The Rfm had an average of 2.45 ± 1.39 MP, the great majority of the MP (63 %) being in the distal area of the proximal third of the thigh; the mVm presented 4.42 ± 2.74 MP on average, with 41 % of them in the middle third of the thigh, distal zone; the intVm had 3.99 + 2.34 MP on average and 58 % of them were located in the proximal area of the middle third of the thigh; the latVm presented an average of 3.88 ± 2.37 MP and 50 % of these were found in the proximal third of the thigh. The biometric localization of the MP is reported in results. The biometric location of the MP, will favor the task, both clinical and surgical of the anterior thigh area.

A Prospective Study to Compare Analgesia from Femoral Obturator Nerve Block with Fascia Iliaca Compartment Block for Acute Preoperative Pain in Elderly Patients with Hip Fracture.

BACKGROUND This study aimed to compare femoral obturator nerve block (FONB) with fascia iliaca compartment block (FICB) in the management of acute preoperative pain in elderly patients with hip fracture. MATERIAL AND METHODS Patients ≥65 years (n=154) diagnosed with hip fracture who had surgery within 48 hours of hospital admission included two groups who received ultrasound-guided nerve block, the FONB group (n=77), and the FICB group (n=77). The visual analog scale (VAS) score for pain, requirement for analgesic drugs, nursing care requirements after hospitalization, post-operative complications, and rehabilitation were compared between the FONB and FICB patient groups. RESULTS The VAS scores after both nerve block procedures were significantly reduced compared with those before both nerve block procedures (P<0.05), but there were no differences on the second day after nerve block. The VAS scores at rest and on exercise in the FONB group were significantly lower than those in the FICB group at 30 min and one day after nerve block (P<0.05). The requirement for postoperative analgesic drugs in the FONB group was significantly lower than that in the FICB group (P=0.048). The incidence of nausea and vertigo in the FICB group were significantly higher than in the FONB group (P=0.031 and P=0.034, respectively). Patients in the FONB group experienced significantly improved quality of postoperative function (P=0.029). CONCLUSIONS Both FONB and FICB provided pain control for elderly patients with hip fracture. However, compared with FICB, FONB resulted in significantly improved analgesia with a reduced requirement for analgesic drugs.

A safe percutaneous technique for the reduction of irreducible femoral neck fractures using ultrasound localization of the femoral vascular and nervous structures at the hip.

We present a safe percutaneous technique for the placement of Kirschner wires into the femoral head to assist in the reduction of irreducible femoral neck fractures using ultrasound to identify the vascular and nervous structures about the hip.From January 2011 to June 2014, a total of 36 patients (25 males and 11 females) were enrolled in this study. Patients were placed on a fracture reduction table for limb traction. After 3 unsuccessful reductions with limb traction, ultrasound-guided localization of the patient's femoral artery, vein, and nerve at the hip was performed. These structures were marked on the overlying skin and then Kirschner wires were inserted into the femoral head avoiding these marked structures. After the surgery, the Kirschner wire insertions were routinely reviewed by ultrasound, the hip fracture reduction and the femoral nerve sensorimotor function were routinely examined as well.All 36 patients with an irreducible variant of a femoral neck fracture showed anatomic reduction under C-arm fluoroscopy using ultrasound to avoid K wire injury to the femoral vascular structures and nerve. No major vascular injury during operation. In post-surgical ultrasound examination, local hematoma formation was not evident. There was normal function of the femoral nerve. On follow-up, there were no infections, wound problems, recurrence of fracture displacement, laxity, or implant breakage.Preoperative ultrasonic localization of the femoral artery, vein, and femoral nerve safely allowed. Kirschner wire placement under C-arm fluoroscopy into the femoral head to assist in fracture reduction. This assisted reduction method for irreducible femoral neck fractures had a number of advantages, including closed anatomic reduction with minimal attempts, used simple equipment, and avoided further destruction of the blood supply to the femoral head.

The Changing Sensory and Sympathetic Innervation of the Young, Adult and Aging Mouse Femur.

Although bone is continually being remodeled and ultimately declines with aging, little is known whether similar changes occur in the sensory and sympathetic nerve fibers that innervate bone. Here, immunohistochemistry and confocal microscopy were used to examine changes in the sensory and sympathetic nerve fibers that innervate the young (10 days post-partum), adult (3 months) and aging (24 months) C57Bl/6 mouse femur. In all three ages examined, the periosteum was the most densely innervated bone compartment. With aging, the total number of sensory and sympathetic nerve fibers clearly declines as the cambium layer of the periosteum dramatically thins. Yet even in the aging femur, there remains a dense sensory and sympathetic innervation of the periosteum. In cortical bone, sensory and sympathetic nerve fibers are largely confined to vascularized Haversian canals and while there is no significant decline in the density of sensory fibers, there was a 75% reduction in sympathetic nerve fibers in the aging vs. adult cortical bone. In contrast, in the bone marrow the overall density/unit area of both sensory and sympathetic nerve fibers appeared to remain largely unchanged across the lifespan. The preferential preservation of sensory nerve fibers suggests that even as bone itself undergoes a marked decline with age, the nociceptors that detect injury and signal skeletal pain remain relatively intact.

Anatomic implications of lesser trochanterplasty.

OBJECTIVE: The aim of this study was to measure the area of iliopsoas tendon attachment and the distance of sciatic nerve, medial circumflex femoral artery (MCFA) and quadratus muscle to lesser trochanter tip, before and after 5, 10, 15 mm depth excision of lesser trochanter. METHODS: A total 15 hips of 8 adult male cadavers were evaluated. Distances between lesser trochanter tip, sciatic nerve, the lower edge of quadratus muscle and MCFA; length and width of quadratus muscle insertion; area of iliopsoas muscle and quadratus muscle insertion was measured before and after sequential 5,10 and 15 mm depth trochanterplasties using 5 mm wide burr parallel to the posterior cortex. RESULTS: Each incremental 5 mm depth bone removal led to significant decrease of tendon area (p=0.001) at each stage. Mean decreases of iliopsoas tendon attachment area with incremental 5 mm burring were 22%±10 with 5 mm, 50%±13 with 10 mm, and 76% ±13 with 15 mm of burring. CONCLUSION: Up to 15 mm lesser trochanter removal did not result in complete detachment of the iliopsoas tendon. Lesser trochanter tip was detected at least 20 mm away from important anatomic structures including quadratus tendon, sciatic nerve, and the medial circumflex femoral artery.

Local chemical sympathectomy of rat bone marrow and its effect on marrow cell composition.

Existing experimental studies of the effect of sympathetic nerve fibers on bone marrow cells are based on the systemic administration of neurotoxic 6-hydroxydopamine. The method of global chemical sympathectomy has some serious disadvantages and could lead to questionable results. We describe a new method of local chemical sympathectomy of rat femoral bone marrow using guanethidine (Ismelin) delivery using an osmotic mini pump. Local guanethidine treatment for 14days led to complete elimination of sympathetic fibers in femoral bone marrow in contrast to bone marrow of contralateral or naïve femurs. Ablation of sympathetic fibers was associated with a loss of rat endothelial cell marker (RECA) indicating immunophenotype changes in blood vessel endothelial cells, but no significant effect of guanethidine was found on the survival of endothelial cells and mesenchymal stem cells in vitro. Moreover, local guanethidine treatment also elicited a significant reduction of Nestin+/SDF1+ mesenchymal stem cells and c-Kit+/CD90+ hematopoietic stem cells in femoral bone marrow. Tissue-specific chemical sympathectomy of rat bone marrow by guanethidine overcomes some of the drawbacks of systemic administration of neurotoxic compounds like 6-hydroxydopamine and delivers unequivocal evidence on the effects of sympathetic innervation on the cell content of bone marrow.

Malignant Peripheral Nerve Sheath Tumor of the Femur: A Rare Diagnosis Supported by Complete Immunohistochemical Loss of H3K27me3.

The histological diagnosis of malignant peripheral nerve sheath tumor (MPNST) is challenging because of the wide morphological spectrum and suboptimal performance of conventional immunohistochemical markers. MPNST arising primarily in the bone is exceptional, and its definitive diagnosis, particularly out of the neurofibromatosis type 1 (NF1) context, is even more problematic. Recurrent inactivation of EED or SUZ12 in a majority of MPNSTs results in a complete loss of trimethylated histone H3 at lysine 27 (H3K27me3) immunoreactivity, making it a highly specific biomarker of MPNSTs. In this article, we report a case of sporadic MPNST of the proximal femur that showed complete loss of H3K27me3. The patient was treated with limb-sparing surgery and postoperative radiotherapy. He developed multiple lung and bone metastases 4 months after surgery. Our case confirms the utility of H3K27me3 immunohistochemistry to yield a definitive diagnosis of sporadic MPNST in a rare primary site.

Radiation-Induced Glandular Malignant Peripheral Nerve Sheath Tumor.

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft-tissue tumors. They can occur in patients with neurofibromatosis type-1 (NF-1) or as sporadic tumors. Only 10% of MPNSTs are radiation induced. Divergent differentiation in MPNSTs can occur in 15% of cases and may include cartilage, bone, skeletal muscle, blood vessels, and very rarely well-formed glands, the latter typically described in NF-1-associated MPNSTs. We report an exceedingly rare case of radiation induced glandular MPNST arising in a neurofibroma of the femoral nerve in a patient previously irradiated for endometrial carcinoma.

The Direct Anterior Approach for Hip Revision: Accessing the Entire Femoral Diaphysis Without Endangering the Nerve Supply.

BACKGROUND: The direct anterior approach (DAA) to the hip has been criticized as an approach that is limited to primary arthroplasty only. Our study objective was to demonstrate, in a cadaveric setting, that an alternate extension of the DAA can be used to reach the femur at the posterior border of the lateral vastus muscle without endangering the nerve supply. METHODS: The iliotibial tract is split anteriorly and pulled laterally, thereby opening the interval to the lateral-posterior aspect of the vastus muscle. The muscle fascia is incised at the posterior border to access the femoral diaphysis. The vastus mobilization is started distally and laterally to the greater trochanter, leaving a muscular bridge between the vastus and the medial gluteal muscle intact. If it is necessary to open the femoral cavity for implant retrieval, we perform an anterior wall osteotomy instead of an extended trochanteric osteotomy. RESULTS: It was possible to split the iliotibial band and pull it laterally, thereby exposing the entire vastus lateralis muscle. The junction of the vastus lateralis and vastus intermedius was not encountered in all cases, nor was the nerve supply with all nerve fibers in that interval. CONCLUSION: The alternate technique described here for accessing the femoral diaphysis allows for easy access to the lateral aspect of the vastus lateralis and the femoral diaphysis. Using this technique, it should also be possible to access the femur and perform all necessary reconstructive procedures on it without damaging the surrounding nerve structures.

Bone Injury and Repair Trigger Central and Peripheral NPY Neuronal Pathways.

Bone repair is a specialized type of wound repair controlled by complex multi-factorial events. The nervous system is recognized as one of the key regulators of bone mass, thereby suggesting a role for neuronal pathways in bone homeostasis. However, in the context of bone injury and repair, little is known on the interplay between the nervous system and bone. Here, we addressed the neuropeptide Y (NPY) neuronal arm during the initial stages of bone repair encompassing the inflammatory response and ossification phases in femoral-defect mouse model. Spatial and temporal analysis of transcriptional and protein levels of NPY and its receptors, Y1R and Y2R, reported to be involved in bone homeostasis, was performed in bone, dorsal root ganglia (DRG) and hypothalamus after femoral injury. The results showed that NPY system activity is increased in a time- and space-dependent manner during bone repair. Y1R expression was trigged in both bone and DRG throughout the inflammatory phase, while a Y2R response was restricted to the hypothalamus and at a later stage, during the ossification step. Our results provide new insights into the involvement of NPY neuronal pathways in bone repair.

Small femoral offset is a risk factor for lateral femoral cutaneous nerve injury during total hip arthroplasty using a direct anterior approach.

INTRODUCTION: Lateral femoral cutaneous nerve (LFCN) injury is a risk specific to the direct anterior approach (DAA) for total hip arthroplasty (THA). However, prevention strategies have not been established. This study aimed to identify the predisposing factors determining LFCN injury during THA via a DAA. HYPOTHESIS: Patients with LFCN injury after THA via DAA would demonstrate predisposing factors. MATERIAL AND METHODS: LFCN injury was identified using a patient questionnaire. Potential factors predisposing to LFCN injury were identified in four categories in patient records: patient factors (age, sex, BMI, diagnosis and range of hip motion), surgical factors (surgical time and surgeon's experience of the DAA), preoperative radiographic factors (neck-shaft angle, femoral offset, acetabular offset, total offset and length of muscle on computed tomography axial image) and radiographic changes (differences between each offset pre- and post-surgery). Multivariate analysis was performed to identify risk factors for LFCN injury during this surgery. RESULTS: After application of inclusion and exclusion criteria, 102 hips (28 with LFCN injury; 74 without) in 102 patients (17 males, 85 females; mean age 66.0 years [range, 26-88 years]) were included. Univariate analysis of patients with and without LFCN injury revealed that small preoperative femoral offset and short preoperative long axis of the tensor fascia lata were statistically significant risk factors for LFCN injury (P=0.004, and P=0.01, respectively). Multivariate analysis showed that small preoperative femoral offset was the only independent risk factor for LFCN injury (odds ratio, 0.895; 95% Confidence Interval, 0.817-0.981; P=0.0018). DISCUSSION: Smaller femoral offset was a significant risk factor for LFCN injury following THA via a DAA. Our recommendations are that careful attention should be paid to the skin-fascia incision and subcutaneous exposure, and that excessive retraction of the sartorius muscle and tensor fascia lata should be avoided, to reduce the risk of LFCN injury in patients with a small femoral offset. LEVEL OF EVIDENCE: IV, retrospective historical cohort study.

NGF-TrkA Signaling by Sensory Nerves Coordinates the Vascularization and Ossification of Developing Endochondral Bone.

Developing tissues dictate the amount and type of innervation they require by secreting neurotrophins, which promote neuronal survival by activating distinct tyrosine kinase receptors. Here, we show that nerve growth factor (NGF) signaling through neurotrophic tyrosine kinase receptor type 1 (TrkA) directs innervation of the developing mouse femur to promote vascularization and osteoprogenitor lineage progression. At the start of primary ossification, TrkA-positive axons were observed at perichondrial bone surfaces, coincident with NGF expression in cells adjacent to centers of incipient ossification. Inactivation of TrkA signaling during embryogenesis in TrkA(F592A) mice impaired innervation, delayed vascular invasion of the primary and secondary ossification centers, decreased numbers of Osx-expressing osteoprogenitors, and decreased femoral length and volume. These same phenotypic abnormalities were observed in mice following tamoxifen-induced disruption of NGF in Col2-expressing perichondrial osteochondral progenitors. We conclude that NGF serves as a skeletal neurotrophin to promote sensory innervation of developing long bones, a process critical for normal primary and secondary ossification.

Can Flexible Instruments Create Adequate Femoral Tunnel Lengths at 90° of Knee Flexion in Anterior Cruciate Ligament Reconstruction?

PURPOSE: This study aims to study femoral tunnel lengths drilled with a flexible reamer and the distance to important lateral structures obtained by flexing the knee at various angles and by drilling the guide pins arthroscopically to resemble clinical practice. The purpose of this cadaveric study was twofold: 1. to determine whether femoral tunnel lengths of greater than 20 mm can be created with a flexible reamer system at 90 ° of knee flexion and 2. to determine whether the lateral structures of the knee are safe with this technique. METHODS: Ten fresh cadaveric knees were utilized. The intra-osseous length can be measured with a specially de - signed flexible guide pin. Flexible pins were inserted with the knee at 70°, 90°, and 120° of flexion. The intra-osseous length was measured with the measuring device. Each speci - men was dissected around the lateral aspect of the knee to identify the critical structures, the common peroneal nerve, and the LCL. The distance from the guide pins to the com - mon peroneal nerve and femoral attachment of the LCL were measured with a standard flexible paper ruler to the nearest millimeter. RESULTS: There is a trend for progressively increasing mean intra-osseous length associated with increased flexion of the knee. The mean intra-osseous length for 70° flexion was 25.2 mm (20 mm to 32 mm), which was statistically significant when compared to mean intra-osseous lengths of 32.1 mm (22 mm to 45 mm) and 38.0 mm (34 mm to 45 mm) in the 90° and 120° flexion groups, respectively (p < 0.05). There were no significant differences among the groups with respect to distance to the LCL. There is a trend toward longer distances to the common peroneal nerve with increased flexion. There was a statistically significant dif - ference when comparing 120° versus 70° (p < 0.05). CONCLUSIONS: This study that shows that adequate femoral tunnel lengths can be safely created without knee hyperflex - ion using flexible instruments via an anteromedial portal.

Porous and Nonporous Nerve Conduits: The Effects of a Hydrogel Luminal Filler With and Without a Neurite-Promoting Moiety.

Nerve conduits prefilled with hydrogels are frequently explored in an attempt to promote nerve regeneration. This study examines the interplay in vivo between the porosity of the conduit wall and the level of bioactivity of the hydrogel used to fill the conduit. Nerve regeneration in porous (P) or nonporous (NP) conduits that were filled with either collagen only or collagen enhanced with a covalently attached neurite-promoting peptide mimic of the glycan human natural killer cell antigen-1 (m-HNK) were compared in a 5 mm critical size defect in the mouse femoral nerve repair model. Although collagen is a cell-friendly matrix that does not differentiate between neural and nonneural cells, the m-HNK-enhanced collagen specifically promotes axon growth and appropriate motor neuron targeting. In this study, animals treated with NP conduits filled with collagen grafted with m-HNK (CollagenHNK) had the best overall functional recovery, based on a range of histomorphometric observations and parameters of functional recovery. Our data indicate that under some conditions, the use of generally cell friendly fillers such as collagen may limit nerve regeneration. This finding is significant, considering the frequent use of collagen-based hydrogels as fillers of nerve conduits.

Long Term Outcome of Conservative Management or Surgical Treatment of Bovine Spastic Paresis: 79 Cases.

OBJECTIVE: To report the long term clinical outcome of calves treated surgically or managed conservatively for bovine spastic paresis of the gastrocnemius (BSP-G), quadriceps femoris muscle (BSP-Q), or mixed muscle involvement (BSP-M). STUDY DESIGN: Retrospective case study. ANIMALS: Calves (n = 79) with bovine spastic paresis. METHODS: Medical records of calves treated by partial tibial neurectomy or managed conservatively for bovine spastic paresis were analyzed for sex, breed, lineage history, and the onset, duration, and severity of clinical signs. Cases were classified as unilateral or bilateral BSP-G, BSP-Q, or BSP-M. Long term follow-up information was obtained by telephone questionnaire. RESULTS: The study group included 26 BSP-G (33%), 16 BSP-Q (20%), and 37 BSP-M (47%) calves. BSP-M and BSP-Q calves were significantly more bilaterally affected compared to BSP-G calves. Twenty-five of 26 BSP-G calves were treated surgically; 86% had complete resolution of clinical signs. Twenty-nine of 37 BSP-M calves were treated surgically; 81.5% improved, but none completely recovered. In all of the conservatively managed BSP-M calves, clinical signs gradually worsened. None of the BSP-Q calves were treated surgically; in 66.7%, clinical signs gradually worsened and 33.3% of calves spontaneously improved. CONCLUSION: Partial tibial neurectomy is advocated for the treatment of BSP-G and in selected cases of BSP-M. However, only partial resolution of clinical signs should be expected for BSP-M. No surgical treatment exists for BSP-Q calves, although spontaneous improvement is possible.

Salicylic acid-based poly(anhydride-ester) nerve guidance conduits: Impact of localized drug release on nerve regeneration.

Nerve guidance conduits (NGCs) can serve as physical scaffolds aligning and supporting regenerating cells while preventing scar tissue formation that often interferes with the regeneration process. Numerous studies have focused on functionalizing NGCs with neurotrophic factors, for example, to support nerve regeneration over longer gaps, but few directly incorporate therapeutic agents. Herein, we fabricated NGCs from a polyanhydride comprised of salicylic acid (SA), a nonsteroidal anti-inflammatory drug, then performed in vitro and in vivo assays. In vitro studies included cytotoxicity, anti-inflammatory response, and NGC porosity measurements. To prepare for implantation, type I collagen hydrogels were used as NGC luminal fillers to further enhance the axonal regeneration process. For the in vivo studies, SA-NGCs were implanted in femoral nerves of mice for 16 weeks and evaluated for functional recovery. The SA-based NGCs functioned as both a drug delivery vehicle capable of reducing inflammation and scar tissue formation because of SA release as well as a tissue scaffold that promotes peripheral nerve regeneration and functional recovery.

Alterations of sympathetic nerve fibers in avascular necrosis of femoral head.

OBJECTIVES: Avascular necrosis of the femoral head (ANFH) was mainly due to alterations of bone vascularity. And noradrenaline (NA), as the neurotransmitter of the sympathetic nervous system (SNS), leads to the vasoconstriction by activating its α-Receptor. This study was to explore the nerve fiber density of the femoral head in the rabbit model of ANFH. METHODS: Twenty New Zealand white rabbits were used in this study. The rabbit model of ANFH was established by the injection of methylprednisolone acetate. The nerve fiber density and distribution in the femoral head was determined using an Olympus BH2 microscope. RESULTS: Significant fewer sympathetic nerve fibers was found in the ANFH intertrochanteric bone samples (P = 0.036) with osteonecrosis. The number of sympathetic nerve fibers was compared between the two groups. And less sympathetic nerve fibers were found in later stage ANFH samples in comparison with those of early stages. CONCLUSIONS: ANFH might be preceded by an inflammatory reaction, and an inflammatory response might lead to arthritic changes in tissue samples, which in turn reduces the number of sympathetic nerve fibers.