Nutrient Artery Research Articles

A study of size of nutrient foramina of humerus of Gujarat region

Delayed union or non-union of fracture shaft humerus occurs if there is damage to nutrient artery of humerus during surgical procedure of open reduction of fracture or by displaced bone fragments of fracture or any soft tissue interposition. This implies vital role of nutrient artery of humerus in fracture healing. 200 human dried humeri were studied for its anatomy of size and number of nutrient foramina. Size of nutrient foramen and thereby size of nutrient artery was decided with use of hypodermic needle No. 20 G & No. 24 G from Eastern medikit Limited. Observations made were compiled and tabulated. In present study, out of 282 nutrient foramina, 98 (35%) were large sized. Single nutrient foramina were found on 63% of humerus which is indicative of single nutrient artery to humerus and amongst them 40% humerus having large sized nutrient foramina. 65% of large sized nutrient dominant foramina were found on humerus having more than one nutrient foramina. 60 (49%) large sized nutrient foramina were found on right side humerus which is points to more use of right arm. Orthopaedic surgeons treating opened or displaced fracture shaft humerus can very well prevent damage to nutrient artery of humerus with sound knowledge of size of nutrient foramina and thereby its artery and add to better prognosis of fracture healing.

Study of diaphyseal nutrient foramina in human typical lower limb long bones

Higher percentage of the nutrient foramina on femur was double while tibia and fibula showed single nutrient foramina. We studied the number, size, direction and foraminal index of diaphysis nutrient foramines of femur tibiae & fibulae in manner in which other authors studied. For the study, 450 dry bones (150 femora, 150 tibiae and 150 fibulae) of adult subjects of unknown sex & age were used from the Anatomy Museum of Government Medical College Miraj & Other medical colleges in Maharashtra, India. Of the 150 femora, tibiae & fibulae dominant foramina were 120(61.54%), 67(42.14%) & 32(20.38%) respectively and secondary foramina were 75(38.46%), 92(57.86%) & 125(79.62%) respectively. This information will be of great importance to orthopedician surgeons performing surgical procedures of the lower limb fractures. Aim and Objective: A detailed study was conducted for: Number and size of nutrient foramina in human lower limb typical long bones; Direction of nutrient foramina; Foraminal index. Keywords: Femur, Fibulae, Foraminal index, Nutrient foramina, Tibiae, Typical lower limb long Bones.

A study on topography of clavicular neurovascular foramina and its surgical implications

Aim: To study the topography of clavicular nutrient foramina. Materials and Methods: The topography of nutrient foramina was studied in 71 clavicles. The mean foraminal index was calculated using Hughes formula. The direction of foramen was also observed. Results: The mean foraminal index was 36.31. The foramen was observed in the middle third of the clavicle in 87.32% cases and medial third in 12.68% cases. The foramen was observed in the inferior surface in 49.3% cases and posterior surface in 50.7% cases. No foramina were observed in the superior surface and in the lateral third of the clavicle. Conclusion: The foramina are mainly observed in the middle third of the clavicle. Standard literatures describe that foramen are mainly seen in the inferior surface but in our study, we observed foramina in both inferior and posterior surface in high frequency. This knowledge of distribution of foramina is of great importance for orthopaedic surgeons in surgeries like internal fixation and bone grafting. Keywords: Clavicle, Foraminal index, Periosteal vessels, Nutrient foramen, Surgical implications.

Anatomical study of nutrient foramina in humerus

Introduction: Knowledge of nutrient foramina is important in surgical procedures. Objective of present study is to know the number, location and direction of nutrient foramina in diaphysis of humerus and to test the significant difference of total length and foraminal index on right and left side separately. Materials and Methods: Total 100 dried humerii of unknown sex (52 of right and 48 of left side) were taken for present study. The identification of nutrient foramen was confirmed with the help of magnifying lens and metallic wire. The total length of humerus and distance of nutrient foramen from proximal end of humerus was measured by sliding caliper and osteometric board. Foraminal index was also calculated. Results: All the examined bones showed single diaphyseal nutrient foramen. Majority of foramina (81%) were present on middle 1/3 of anteromedial surface of shaft of humerus. The direction of these foramina was similarly found in all bones i.e. towards the elbow joint. There were no significant differences between right and left side for total length and foraminal index. Conclusion: An accurate knowledge of the location of nutrient foramina is important in surgical procedures like reduction of fracture, bone grafting and microsurgical vascularized bone transplantation. Keywords: Humerus, Nutrient foramina, Number, Location, Direction, Foraminal index.

Study of nutrient foramina of human tibia of Saurashtra region

Introduction: On the shaft of tibia surface openings for entry of blood vasculature is known as nutrient foramen which leads to nutrient canal to provide a pathway for blood vessels to reach medullary cavity. Topographical information about nutrient foramen is very crucial during various orthopedic surgical procedures. Objective:Present study is conducted to find out the number of nutrient foramina, its location and direction in relation to growing end of bone and to calculate foraminal index of human tibia. Material and Methods:In present study 61(30 right and 31 left sided) tibia bone were studied. Age and sex of the bone were unknown. Only fully intact bone without any disease were included. Surface location and direction of nutrient foramina were recorded. Total length of tibia was measured with osteomatric board. Distance of nutrient foramen from proximal end was measured with digital vernier caliper. And foraminal index was calculated. All data was tabulated and analysed statisticaly. Result:Out of total 61 tibia 95.08% of tibia had one nutrient foramen, 3.28% tibia had two foramen and 1.64% were devoid of nutrient foramen. Almost all (98.33%) of the nutrient foramina were detected on the posterior surface, only 1.67% were on lateral surface. Zone I contained 48.33% and Zone II contained 51.67% of foramina. Not a single bone had foramen in Zone III. Direction of all foramina were towards lower end of tibia except one bone. Conclusion:Thorough knowledge of morphology of nutrient foramina is necessary for preserving the nutrient arterial blood supply. Because it is very crucial in bone grafting, fracture healing, joint replacement therapy and vascularised bone micro surgeries. Keywords:Tibia, Foraminal index, Nutrient foramen, Fracture, Morphometry.

Variation of the Nutrient Foramen of Fibula and its Clinical Significance

Background: The fibula is a long bone located at the lateral aspect of the leg. Its diaphysis is principally nourished by one or more nutrient arteries entering the shaft through an opening referred to as the nutrient foramen. The present findings on the morphometrics of the foramen may be helpful to forensic experts, radiologists and clinicians for diagnosis and management of various bony conditions.
 Materials and Methods: This was a descriptive cross sectional study conducted on fifty dry adult human fibulae collected at the Department of Anatomy, Chitwan Medical College from June to September 2020. Total fibular length along with the number and location of all nutrient foramina present were recorded. Foraminal index of the fibula was calculated as well.
 Results: The study revealed that the average length of Nepalese fibulae was 34.1 ± 1.9 cm. Eighty-eight percent fibula had a single nutrient foramen, 4 % had two and 8 % had none. The most common location was between the medial crest and posterior border (63%, in fibula with single foramen), followed by the medial crest (30%) and between the medial crest and interosseous border (7%). The average foraminal index was 44.01 ± 7.9 % with a range of 34.9 to 65.7 %.
 Conclusion: Single nutrient foramen located at the middle third on posterior aspect was the most common finding. Regional data on the number and location of the foramina would be useful to forensic experts and clinicians for various diagnostic and treatment purposes.

Lunate biomechanics: application to Kienböck's disease and its treatment

Kienböck's disease was initially considered as lunate osteomalacia due to lesions of its nutrient arteries during carpal ligament tears. It has also been suggested following primary fractures, or because of repeated microtrauma. It is only in the past 20 or 30 years that it has appeared as aseptic necrosis. Based on Hultén's hypothesis that a negative radioulnar index was the cause of Kienböck's disease, equalization osteotomies (shortening of the radius or lengthening of the ulna) were developed. The observation of Kienböck's disease in subjects with a positive index and the risk of ulnar abutment after osteotomy led to the introduction of new osteotomies to get around these difficulties, still in the hope of treating the cause of Kienböck's disease. While it has been confirmed that a negative radioulnar index promotes lunate fracture, it clearly does not induce the pathology in the form of necrosis. In this scenario, perilunar osteotomies produce durable decompression, limiting the risk of lunate fracture in case of necrosis by removing the compressive constraints. After comparing the different osteotomies used to treat Kienböck's disease, it seems that the Camembert osteotomy for radius shortening, combined with selective shortening of the ulnar head as described by Sennwald, decompresses the lunate maximally, and protects it long enough for potential natural revascularization to occur.

DIAPHYSEAL NUTRIENT FORAMINA IN DIRED HUMAN ADULT LONG BONES OF UPPER LIMB IN PAKISTAN

BACKGROUND: Large and tiny foramina on long bones allow blood vessels to enter. These foramina, which goby diaphyseal nutrient foramina, are bigger and are found mostly in the long bone shafts, where they enter nutritioncanals that lead to the medullary cavity. These nutrition canals house nutrient arteries and veins, which may be seenin long and irregular bones. These foramina are located in the shafts of long bones and various places in irregularbones. The orientation of the nutrition foramina, which develops quicker than the non-growing end, is determined bythe growing end of the bones.STUDY DESIGN: A cross-sectional StudyDURATION AND PLACE OF STUDY: Department Of Anatomy, Ayub Medical College, Abbottabadfrom jan 2017 to Jan 2018METHODS: The current investigation contained ninety human upper limb long bones. These skeletons were driedand cleaned. Thirty ulnae, 30 radii, and 30 humerii were among them. The anatomy departments of Ayub and KhyberMedical Colleges provided these bones, respectively. It was unknown how old and what gender the bones were. Everybone was examined macroscopically to determine the nutrition foramina’s quantity, orientation, and direction. Simplecounting was done for the number. The foramina were numbered one millimeter from the boundaries. Every locationof the foramina was seen under a microscope. The stiff wire was employed for obliquity and direction.RESULTS: This cross-sectional investigation included 90 lengthy bones of the upper Limb. The long bones of theupper limbs comprise 80% of a single nourishment foramina. There were two nutritional foramina in 18% of theupper limbs’ long bones. The orientation of nutritional foramina was distal in humeri cases. In the cases of radii andulnae, the orientation was proximal.CONCLUSION: The research has supplied further details on the morphology, topography, and foramina index ofthe nutrient foramina. Given the growing popularity of micro-vascular bone transfer, anatomical data about the longbones of the upper limbs is crucial for doctors.KEYWORDS: Bone cortex, ulnae, radii, humerii, nutrient foramina.

Volar and Dorsal Blood Supply to the Lunate: A Cadaveric Study.

Although various studies have proposed vascular and mechanical factors, the etiology of Kienböck disease is unknown. Kienböck theorized that lunatomalacia resulted from traumatic disruption of blood supply and bony nutrition to the lunate. Extraosseous supply to the lunate, as far as volar or dorsal vessels are concerned, is still controversial. This study evaluated the extraosseous nutrient foramina from the dorsal and volar aspects of lunate specimens. A total of 913 specimens from the Hamann-Todd Osteological Collection in Cleveland, Ohio, were examined. The nutrient artery foramina on left and right lunate specimens were examined from dorsal and volar aspects. The number of nutrient artery foramen was tabulated. Age, sex, and race data were collected. Specimens were divided into groups according to the number of nutrient artery foramina, and the dorsal and volar foramina were compared. The average number of foramina on the dorsal aspect of the lunate (1.71) was greater than the volar aspect (1.64), except in specimens younger than 35 years. A greater number of specimens had 3 or more foramina on the dorsal side compared with the volar aspect. Based on this study, there was significant contribution of dorsal arterial vessels to the blood supply of lunate specimens older than 35 years, which contrasts with findings in earlier studies. The disruption of dorsal intercarpal and radiocarpal ligaments leading to the disruption of the dorsal arterial arches may contribute to vascular insufficiency of the lunate and should be evaluated further in the etiopathogenesis of Kienböck disease. [Orthopedics. 2021;44(2):e243-e247.].

Endosteal Vasculature Dominates Along the Tibial Cortical Diaphysis: A Quantitative Magnetic Resonance Imaging Analysis.

Disrupted blood supply has been proposed as an underlying cause for delayed union in tibial shaft fractures (OTA/AO 42). Although tibial blood supply has been qualitatively evaluated, quantitative studies are lacking. The purpose of this project was to quantify the relative contribution of the endosteal supply to the tibial diaphysis. The superficial femoral artery of 8 fresh frozen cadaveric matched pair lower extremities was cannulated. The nutrient artery was ligated at its proximal branch point in experimental limbs. Pregadolinium and postgadolinium enhanced magnetic resonance imaging was performed with high resolution fat-suppressed ultrashort echo time magnetic resonance imaging sequences. Perfusion was assessed in 3 zones (outer, central, and inner cortex) for the proximal, middle, and distal diaphysis, respectively, using custom software to quantify and compare signal intensity between experimental and control limbs. On average, the endosteal system supplied 91.4% (±3.9%) of the cortex and was the predominant blood supply for the inner, central, and outer thirds. The dominance of the endosteal contribution was most pronounced in the inner two-third of the cortex, with more than 97% loss of perfusion. Disruption of the nutrient artery also resulted in 76.3% (±11.2%) loss of perfusion of the outer one-third of the cortex. This quantitative study revealed a predominance of endosteal blood supply to all areas (inner, middle, and outer thirds) of the tibial diaphyseal cortex. To prevent delayed bone healing, surgeons should take care to preserve the remaining periosteal vascular network in fracture patterns in which the nutrient artery has likely been disrupted.

Reptile-like physiology in Early Jurassic stem-mammals

Despite considerable advances in knowledge of the anatomy, ecology and evolution of early mammals, far less is known about their physiology. Evidence is contradictory concerning the timing and fossil groups in which mammalian endothermy arose. To determine the state of metabolic evolution in two of the earliest stem-mammals, the Early Jurassic Morganucodon and Kuehneotherium, we use separate proxies for basal and maximum metabolic rate. Here we report, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that they had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates. Measurements of femoral nutrient foramina show Morganucodon had blood flow rates intermediate between living mammals and reptiles, suggesting maximum metabolic rates increased evolutionarily before basal metabolic rates. Stem mammals lacked the elevated endothermic metabolism of living mammals, highlighting the mosaic nature of mammalian physiological evolution.

A Study of Morphological and Morphometric Variations in Sri Lankan Femoral Diaphysial Nutrient Foramina

A Study of Morphological and Morphometric Variations in Sri Lankan Femoral Diaphysial Nutrient Foramina

Autogenous Arteriovenous Bundle Implantation Maintains Viability Without Increased Immune Response in Large Porcine Bone Allotransplants

BackgroundTransplantation of living allogeneic bone segments may permit reconstruction of large defects, particularly if viability is maintained without immunosuppression. Development of a new autogenous osseous blood supply accomplishes this goal in rodent experimental models. This study evaluates potential systemic and local inflammatory responses to this angiogenesis in a large-animal model. MethodsVascularized allogeneic tibia segments were transplanted orthotopically into matched tibial defects in Yucatan minipigs. Microvascular anastomoses of bone nutrient artery and vein were supplemented by intramedullary placement of an autogenous arteriovenous (AV) bundle in group 1. Group 2 served as a no-angiogenesis control. A 3-drug immunosuppression regimen was withdrawn after 2 weeks. During the 20-week survival period, periodic leukocyte counts and inflammatory cytokine levels were measured. Thereafter, osteocyte survival was quantified and transplant rejection graded by histologic examination and quantitative real-time polymerase chain reaction of immunologic markers. ResultsBoth groups developed an initial systemic response, which resolved after 4 to 6 weeks. No differences were seen in blood cytokine levels. Interleukin 2 expression was diminished in group 1 tibiae. As expected, nutrient pedicles had thrombosed without sustained immunosuppression, occluded by intimal hyperplasia. In group 1, angiogenesis from the autogenous AV bundle resulted in significantly less osteonecrosis (P = .04) and fibrosis (P = .02) than group 2 allotransplants. ConclusionsSystemic immune responses to large-bone allotransplants were not increased by generation of an autogenous osseous blood supply within porcine tibial bone allotransplants. Implanted AV bundles diminished inflammation and fibrosis and improved bone viability when compared to no-angiogenesis controls.

Estimation of sex from the metacarpal dimensions at the nutrient foramen in white South Africans

ABSTRACT Sex estimation is important in both forensic and archaeological cases and requires a variety of bones and measurements to obtain accurate estimates. Discriminant function analysis equations on postcranial elements are associated with population specificity, hence the need to generate equations for each population group. The current study examined the utility of the measurements around the nutrient foramen of the metacarpals for sex estimation from white South Africans. The study utilized 520 left metacarpals from 104 adult skeletons of white South Africans of known sex (53 males, 51 females) and age at death (range 21 to 65 years) obtained from the Raymond A. Dart Collection of Human Skeletons at the University of the Witwatersrand. Measurements that were subjected to stepwise and direct discriminant function analyses include total length, distance from proximal end to nutrient foramina, circumference, palmar-dorsal diameter, and mediolateral diameter at the level of the nutrient foramen. Combinations of breadth measurements of the first and second metacarpals produced high sex estimation scores ranging from 82% to 91% (stepwise discriminant function analysis) and 82–94% (direct discriminant function analysis) indicating that the dimensions around the nutrient foramen of the metacarpals are useful in sex estimation and can be used in fragmentary bones.

Injury of the Tibial Nutrient Artery Canal during External Fixation for Lower Extremity Fractures: A Computed Tomography Study

The tibial nutrient artery (TNA) is the major diaphyseal artery of the tibia supplying two thirds of the inner osseous cortex. Hence, iatrogenic injury of the TNA endangers the integrity of the tibial blood supply and may compromise fracture healing. The incidence of its injury in the setting of external fixation for lower limb fractures has not been previously investigated. The aim of this study was to evaluate the incidence of TNA injury in the context of external fixation and to characterize the topography of the fixator pins in relation to the TNA canal (TNAC). Patients who underwent external fixation for distal femoral fractures and for tibial (proximal, shaft, and distal) fractures and had a postoperative computed tomography study were retrospectively included. The following parameters were retrieved: 1) Pin characteristics (orientation and cortical position of the pins), 2) The anatomic relationship between the TNAC and external fixation pin (topography above/below and at the level of the TNAC, and the distance between the pin and medial tibial plateau and/or the medial malleolus), and 3) The incidence of TNAC injury (complete/partial disruption of TNA lumen). A total of 105 patients with 214 tibial pins were analyzed. In 27 patients (26%), the TNAC was completely injured by the pins of the external fixator. In 13 patients (12%), the TNAC was partially injured. Of the 214 analyzed pins, 85 pins (40%) were located at the level of the TNAC (the TNAC and the pin are seen on the same axial slice). Most pins that were applied at the level of the TNAC belonged to a knee-bridging external fixator. Of those, ninety-three percent of the pins were anteromedially applied according to published surgical guidelines. Six percent of the pins were applied through the tibial crest and 1% anterolaterally. Of those 85 pins, 42 pins (49%) injured the TNAC at least partially. Based on the analyzed pins and the incidence of partial and complete injury of the TNAC, we observed that the tibial segment at which the tibial nutrient artery is endangered was located approximately (95% CI: 13–15 cm) from the medial tibia plateau and (95% CI: 22–25 cm) from the medial malleolus. Thus, TNAC injury by external fixation pins in the context of lower limb fractures can be considered common. Almost half of the pins applied at the middle third of the tibia injured the TNA, despite adherence to published surgical guidelines for external fixation. When possible, pin application at the middle third of tibia should be avoided to circumvent iatrogenic injury of the TNA and to safeguard tibial blood supply.

Sample specific sex estimation method using parameters around dominant nutrient foramina in unknown femur bones collection of contemporary Egyptians

AbstractBecause there is no widely accepted sexing method of fragmented femoral diaphyses, we argue that the diaphyseal diameters and circumference around nutrient foramina (NF) have comparable sex discrimination capacity to their mid‐shaft counterparts. Construction of reliable reference sample (n = 61, 29 males and 32 females) using the undocumented Alexandria University Osteological Collection was contingent upon consistent sex estimation of the epiphyses using population and sample specific methods. Statistically significant size differences were found between the males and females diaphyseal measurements around NF. Low intraobserver measurements error and high sexual dimorphism indices were observed in the new measurements at NF level. The logistic regression analysis revealed that combinations of anteroposterior diameter and circumference at both levels were the optimal models for sex classification. Testing in the holdout sample showed complete agreement in the results between both models. The best model at the level of NF achieved consistent total sex allocation of 81.1% with high probability >0.80 of correct estimates in approximately 60% of the reference sample. A great applicability pertinent to sex estimation of a tubular fragment of femur bearing a single NF using the diaphyseal measurements around it because the maximal length is not required to determine the location of the mid‐shaft measurements.

Anatomy of pisiform blood supply and feasibility of vascularized pisiform transfer for avascular necrosis of lunate based on digital technique

To provide anatomical basis for vascularized pisiform transfer in the treatment of advanced avascular necrosis of the lunate (Kienböck's disease) by studying its morphology and blood supply pattern based on digital technique. Twelve adult fresh wrist joint specimens were selected and treated with gelatin-lead oxide solution from ulnar or radial artery. Then the three-dimensional (3D) images of the pisiform and lunate were reconstructed by micro-CT scanning and Mimics software. The morphologies of pisiform and lunate were observed and the longitudinal diameter, transverse diameter, and thickness of pisiform and lunate were measured. The main blood supply sources of pisiform were observed. The number, diameter, and distribution of nutrient foramina at proximal, distal, radial, and ulnar sides of pisiform were recorded. The anatomic parameters of the pedicles (branch of trunk of ulnar artery, carpal epithelial branch, descending branch of carpal epithelial branch, recurrent branch of deep palmar branch) were measured, including the outer diameter of pedicle initiation, distance of pedicle from pisiform, and distance of pedicle from lunate. There were significant differences in the longitudinal and transverse diameters between pisiform and lunate ( t=6.653, P=0.000; t=6.265, P=0.000), but there was no significant difference in thickness ( t= 1.269, P=0.109). The distal, proximal, radial, and ulnar sides of pisiform had nutrient vessels. The nutrient foramina at proximal side were significantly more than that at distal side ( P<0.05), but there was no significant difference in the diameter of nutrient foramina between different sides ( P>0.05). The outer diameter of pedicle initiation of the recurrent branch of deep palmar branch was significantly smaller than the carpal epithelial branch and descending branch of carpal epithelial branch ( P<0.05). There was no significant difference in the distance of pedicle from pisiform/lunate between branch of trunk of ulnar artery and recurrent branch of deep palmar branch ( P>0.05), and between carpal epithelial branch and descending branch of carpal epithelial branch ( P>0.05). But the differences between the other vascular pedicles were significant ( P<0.05). There are abundant nutrient vessels at the proximal and ulnar sides of pisiform, so excessive stripping of the proximal and ulnar soft tissues should be avoided during the vascularized pisiform transfer. It is feasible to treat advanced Kienböck's disease by pisiform transfer with the carpal epithelial branch of ulnar artery and the descending branch.

The Anatomy of the Tibial Nutrient Artery Canal-An Investigation of 106 Patients Using Multi-Detector Computed Tomography.

Radiologic evaluation of the tibial nutrient artery is clinically important as disruption of tibial blood supply is a risk factor for delayed or non-union of tibial fractures. Damage to the tibial nutrient artery canal (TNAC) may occur by a traversing fracture or iatrogenic cause in the context of pin/screw placement. Furthermore, TNAC could be misdiagnosed as a stress fracture. The aim of this study was to characterize the normal anatomy of TNAC and to delineate its gender and side-specific differences. Patients who underwent contrast-enhanced computed-tomography encompassing the pelvis and lower extremities were included. TNAC was identified with an external and internal foramen and a traversing intercortical canal. Various anatomical morphometrics were evaluated: total number of nutrient canals, angular position of the outer and inner nutrient foramina, absolute and relative position of the nutrient foramina, as well as the intercortical canal length with respect to tibial length. The majority of patients of both genders had only one tibial nutrient canal, multiple canals or complete absence were rare. In most cases, the outer nutrient foramen was found on the posterolateral aspect of the upper-third of tibia at about 32% of tibial length; the inner foramen was found at the middle third of the tibia (41% of tibial length). The course of nutrient canal was mostly cranio-caudal with a small, but significant difference in relative canal length: 8.5% vs. 10% of tibial length for females and males, respectively. The angular location of the outer and inner foramen was between 20–30° and did not reveal a statistically significant difference between genders. No statistically significant side specific differences were found for all analyzed parameters and both genders. The clinical relevance of this anatomical study pertains to establishing “safe corridors” of pin/screw insertion in the context of surgical management of tibial fractures in order to avoid iatrogenic disruption of tibial blood supply.

Static Muscle Stretching Enhances Vascular Responsiveness of the Tibial Nutrient Artery

The magnitude of bone formation and remodeling is linked to both the magnitude of strain placed on the bone and the perfusion of bone. We have previously shown that daily static stretching of the ankle flexor muscles in aged rats results in increased blood flow to the stretched muscles and to the proximal tibial metaphasis during walking exercise. The purpose of this study was to determine the effects of daily static muscle stretching on vasoreactivity of the nutrient artery that perfuses the proximal tibial metaphasis. Static stretching of ankle flexor muscles was performed in aged male Fischer 344 rats (20 months) by placement of a dorsiflexion splint on the left ankle for 30 min/day, 5d/wk for 4wks. The right hindlimb served as a contralateral control (unstretched) limb. After the 4 wk stretching intervention, the tibial nutrient artery was isolated from both the stretched and unstretched limb. Vasoconstrictor responses to the adrenergic agonist, phenylephrine (10‐9‐10‐4M) and vasodilatory responses to acetylcholine (10‐9‐10‐4M) and Dea‐NONO‐ate (10‐9‐10‐4M) were evaluated. Vasoconstrictor responses to phenylephrine were significantly increased in the tibial nutrient artery from the stretched limb as compared to those from the unstretched limb (maximal constriction, stretched limb = 54±4%, maximal constriction, unstretched limb = 42±6%; P&lt;0.05 stretched vs. unstretched). Endothelium‐dependent vasodilation to acetylcholine was also significantly increased in the tibial nutrient artery from the stretched limb (maximal dilation = 62±5%) as compared to the unstretched limb (maximal dilation = 41±5%); P&lt;0.01, stretched vs. unstretched). Endothelium‐independent dilation to the NO donor, Dea‐NONO‐ate was not different in the tibial nutrient arteries from the stretched and unstretched limbs. These data indicate that static muscle stretching alters the reactivity of both the smooth muscle and the endothelium of the tibial nutrient artery, leading to enhanced vasoconstrictor and vasodilatory responsiveness of the artery. This enhancement of vascular function in the nutrient artery may contribute to increased perfusion of the tibia during walking exercise following 4 weeks of daily static stretching.Support or Funding InformationSupported By: NIH R15AG055029

Effects of Aging and Exercise Training on Vasomotor Function of Bone Resistance Arteries and Bone Blood Flow

Adequate skeletal perfusion is necessary to maintain bone remodeling processes, and decrements in bone arterial function and regional blood flow may lead to conditions such as osteoporosis. Aging elicits progressive bone loss, associated with impaired bone vasomotor function and perfusion, that can lead to osteoporosis. Although these age‐related adaptations are ameliorated via exercise training, the specific mechanisms underlying exercise‐induced alterations of bone vasomotor function with aging remain largely unknown. The purpose of this study was to elucidate the age‐ and exercise‐induced vasomotor adaptations of the bone principal nutrient artery and subsequent alterations in bone blood flow.Young and old male Fischer‐344 rats underwent treadmill exercise training (15 m/min, 15° incline, 1hr/day, 5 days/wk for 10–12 wks) or remained sedentary in cages. At the end of the experimental period, the femoral principal nutrient artery (PNA) was isolated, cannulated, and pressurized for vascular response studies. Vasoconstrictor responses of the PNA were assessed in vitro using α‐adrenergic agonist phenylephrine (PE, 10−9–10−4 M), receptor‐independent potassium chloride (KCl, 10–100 mM) and myogenic responsiveness to increasing intraluminal pressure (0 to 140 cmH2O). Endothelium‐dependent (ACh, 10−9–10−4 M) and ‐independent (Dea‐NONOate, 10−9–10−4 M) vasodilator responses were also evaluated. Additionally, regional blood flow to the femur was measured at rest and during exercise using radiolabeled microspheres.Vasomotor responses to agonists for constriction (PE, KCl) and dilation (ACh, Dea‐NONOate) decreased with aging. In contrast, myogenic responsiveness in old rats was greater compared with young rats (p&lt;0.05). Vasoconstrictor response to KCl was greater after training in both young and old rats as compared to the sedentary rats. Exercise‐trained old rats also showed increased vasoconstrictor responses to PE and myogenic responsiveness; however, no significant difference was shown in young rats (p&lt;0.05). Exercise training enhanced endothelium‐dependent vasodilation in both young and old rats; however, no significant exercise effect was observed in endothelium‐independent vasodilation (p&lt;0.05). Regional femur blood flow to the proximal and distal metaphysis and epiphysis, as well as diaphyseal marrow, was lower in aged rats compared to young rats at rest. However, exercise‐trained old rats showed significantly increased regional blood flow during exercise compared with old SED rats (p&lt;0.05).These results demonstrate vasomotor responses are impaired in the femoral PNA from aged rats; however, endurance training intervention at advancing age can reverse vasomotor deficits including vasoconstrictor and vasodilator response in bone resistance arteries and enhance regional bone and marrow blood flow. Such changes in bone and marrow perfusion could play an important role in enhancing the quality and strength of bone in old age following exercise training.Support or Funding InformationNIH grant AG055029