Perforation of the coronoid-olecranon septum. Humero-ulnar relationships in Netherlands and African populations

The mechanical interaction of the humerus and ulna during articulation has been examined in skeletal material from African and European populations. It was found that the presence or absence of perforation of the humeral septum and the thickness of the septum when unperforated can be predicted with considerable accuracy when two factors are known: the length of the coronoid and olecranon processes of the ulna relative to the minimum diameter of the trochlea humeri, and the total angle of movement at the elbow from full extension to full flexion. The influences which control either or both of these factors also determine the thickness of the septum of the humerus. These influences are not well known and there is opportunity for both genetic and environmental effects. The coefficients of correlation between septum thickness, flexion angle, humeral robusticity, minimum circumference of the humerus, trochlea diameter and brachial index are given. Septum thickness is correlated more highly with trochlea diameter than with robusticity or minimum circumference of the humerus. The higher frequency of perforation of the septum in the African sample (47%) compared with the European (6%) is associated with a greater range of movement at the elbow in the Africans. Bilateral, sexual and population differences in the frequency of perforation of the humeral septum may be associated with differences in the extent of movement at the elbow joint. Variation in this feature, in turn, may be associated with muscularity and somatotype.     

Prediction of joint center location by customizable multiple regressions: Application to clavicle,scapula and humerus

Accurate spatial location of joint center (JC) is a key issue in motion analysis since JC locations are used to define standardized anatomical frames, in which results are represented. Accurate and reproducible JC location is important for data comparison and data exchange. This paper presents a method for JC locations based on the multiple regression algorithms without preliminary assumption on the behavior of the joint-of-interest. Regression equations were obtained from manually palpable ALs on each bone-of-interest. Results are presented for all joint surfaces found on the clavicle, scapula and humeral bone. Mean accuracy errors on the JC locations obtained on dry bones were 5.2±2.5 mm for the humeral head, 2.5±1.1 mm for the humeral trochlea, 2.3±0.9 mm for the humeral capitulum, 8.2±3.9 mm for the scapula glenoid cavity, 7.2±3.2 mm for the scapular aspect of the acromio-clavicular joint, 3.5±1.8 mm for the clavicular aspect of the sternoclavicular joint and 3.2±1.4 mm for the clavicular aspect of the acromio-clavicular joint. In-vitro and in-vivo validation accuracy was 5.3 and 8.5 mm, respectively, for the humeral head center location. Regression coefficients for joint radius dimension and joint surface orientation were also processed and reported in this paper.     

Stress and the etiology of osteoarthritis

Although degenerative joint disease is an old and exceedingly common problem, clinical investigators have not reached a consensus regarding the etiology of this disease. Comparative osteological analysis of the knee, hip, shoulder, and elbow joints of 798 individuals from four human skeletal populations (Black and White Americans, Pueblo Indians, and Alaskan Eskimos) indicates that age of onset, frequency, and location of degenerative changes are directly related to the nature and degree of environmentally associated stress, as reflected by the variable life styles of the populations sampled. Eskimos have the earliest onset and most severe involvement for all four joints studied, the right side is usually more affected than the left, and Blacks are more frequently involved than Whites in the knee, shoulder, and elbow. Functional stress, when constant and severe in nature, becomes the primary focus of degenerative disease, but other background contributing agents such as age, sex, and hormonal influence must not be ignored.     

The accuracy of measuring glenohumeral motion with a surface humeral cuff

Conclusions about normal and pathologic shoulder motion are frequently made from studies using skin surface markers, yet accuracy of such sensors representing humeral motion is not well known. Nineteen subjects were investigated with flock of birds electromagnetic sensors attached to transcortical pins placed into the scapula and humerus, and a thermoplastic cuff secured on the arm. Subjects completed two repetitions of raising and lowering the arm in the sagittal, scapular and coronal planes, as well as shoulder internal and external rotation with the elbow at the side and abducted to 90°. Humeral motion was recorded simultaneously from surface and bone fixed sensors. The average magnitude of error was calculated for the surface and bone fixed measurements throughout the range of motion. ANOVA tested for differences across angles of elevation, raising and lowering, and differences in body mass index. For all five motions tested, the plane of elevation rotation average absolute error ranged from 0-2°, while the humeral elevation rotation average error ranged from 0-4°. The axial rotation average absolute error was much greater, ranging from 5° during elevation motions to approaching 30° at maximum excursion of internal/external rotation motions. Average absolute error was greater in subjects with body mass index greater than 25. Surface sensors are an accurate way of measuring humeral elevation rotations and plane of elevation rotations. Conversely, there is a large amount of average error for axial rotations when using a humeral cuff to measure glenohumeral internal/external rotation as the primary motion.     

LCP结合自体髂骨联合RBX植骨治疗非感染萎缩型肱骨干骨不连的体会

目的:探讨锁定加压钢板(Locked compression plate,LCP)结合自体髂骨联合重组合异种骨(recombinant bone xenograft,RBX)植骨治疗非感染萎缩型肱骨干骨不连的疗效及相关体会。方法:于2009年2月-2015年9月期间,应用LCP结合自体髂骨联合RBX植骨治疗了15例非感染萎缩型肱骨干骨不连。结果:本组获随访9-29个月,骨不连均获得愈合。肩关节功能优良率86.7%,肘关节功能优良率100%。结论:依据本组研究及相关文献报道,LCP结合自体髂骨植骨联合RBX植骨可提高骨不连愈合率。     

Heterogeneity of the mechanical properties of demineralized bone

Knowledge of the mechanical properties of the collagenous component of bone is required for composite modeling of bone tissue and for understanding the age- and disease-related reductions in the ductility and strength of bone. The overall goal of this study was to investigate the heterogeneity of the mechanical properties of demineralized bone which remains unexplained and may be due to differences in the collagen structure or organization or in experimental protocols. Uniaxial tension tests were conducted to measure the elastic and failure properties of demineralized human femoral (n = 10) and tibial (n = 13) and bovine humeral (n = 8) and tibial (n = 8) cortical bone. Elastic modulus differed between groups (p = 0.02), varying from 275 +/- 94 MPa (mean +/- SD) to 450 + 50 MPa. Similarly, ultimate stress varied across groups from 15 + 4.2 to 26 + 4.7 MPa (p = 0.03). No significant differences in strain-to-failure were observed between any groups in this study (pooled mean of 8.4 +/- 1.6%; p = 0.42). However, Bowman et al. (1996) reported an average ultimate strain of 12.3 +/- 0.5% for demineralized bovine humeral bone, nearly 40% higher than our value. Taken together, it follows that all the monotonic mechanical properties of demineralized bone can display substantial heterogeneity. Future studies directed at explaining such differences may therefore provide insight into aging and disease of bone tissue.     

Effect of Bone Mineral Density on Rotator Cuff Tear: An Osteoporotic Rabbit Model

IntroductionAn increased bone mineral density (BMD) in the proximity to tendon insertion can improve rotator cuff repair and healing. However, how a decrease of BMD in the humeral head affects the biomechanical properties of the rotator cuff tendon is still unclear. Previous studies have demonstrated ovariectomy in animals to lead to osteoporosis and decreased BMD, and Teriparatide (PTH) administration to improve BMD and strength of bone. This study aimed to explore the correlation between humeral head BMD and infraspinatus (ISP) tendon insertion strength, and if an increase in bone quantity of the humeral head can improve the strength of the rotator cuff.ResultsSignificant differences were observed in the measured humeral head BMD of the Control and OVX-PTH groups compared to the OVX-Saline group (P = 0.0004 and P = 0.0024, respectively). No significant difference was found in failure stress among the three groups, but an expected trend with the control group and OVX-PTH group presenting higher failure strength compared to the OVX-Saline group. BMD at the humeral head showed a positive linear correlation with stress (r² = 0.54). Histology results showed the superiority in OVX-PTH group ISP enthesis compared to the OVX-Saline group.ConclusionBone loss of the humeral head leads to decreased tendon/bone insertion strength of the infraspinatus tendon enthesis. Teriparatide administration can increase bone density of the humeral head and may improve the mechanical properties of the infraspinatus tendon enthesis.     

尺骨鹰嘴截骨和内外侧入路非截骨入路治疗肱骨髁间骨折的效果比较分析

目的:比较尺骨鹰嘴截骨和内外侧非截骨入路治疗肱骨髁间骨折的效果。方法:前瞻性选取2016年9月至2018年9月在本院进行治疗的76例肱骨髁间骨折患者作为研究对象,按照数字表法随机分为截骨组和非截骨组各38例,截骨组采用尺骨鹰嘴截骨入路进行治疗,非截骨组采用内外侧入路非截骨入路进行治疗。比较两组患者手术时间、术中出血量、术后24 h出血量、X线暴露时间,术后12个月骨折延迟愈合、尺神经麻痹、关节挛缩、骨关节炎等并发症的发生率以及疗效。结果:截骨组手术时间、术中出血量、术后24 h出血量、X线暴露时间明显低于非截骨组,差异均有统计学意义(P0.05)。截骨组并发症的发生率为13.16%,非截骨组并发症发生率为26.32%,两组比较差异无统计学意义(P0.05)。截骨组优良率为84.21%,非截骨组优良率为71.05%,两组比较差异无统计学意义(P0.05)。截骨组C1、C2、C3型肱骨髁间骨折术后肘关节评分优良率分别为78.57%、88.23%、85.71%,非截骨组C1、C2、C3型肱骨髁间骨折术后肘关节评分优良率分别为86.66%、73.33%、62.50%,非截骨组C1型肱骨髁间骨折术后肘关节评分优良率略高于截骨组,截骨组C2、C3型肱骨髁间骨折术后肘关节评分优良率略高于非截骨组,但两组不同AO分型优良率比较差异无统计学意义(P0.05)。结论:肱骨髁间骨折患者应用尺骨鹰嘴截骨入路手术较肱三头肌内外侧非截骨入路手术具有一定的临床优势,可显著减少手术时间、术中出血量、术后24h出血量以及术中X线照射时间,并且术后肘关节功能恢复较好,在粉碎较为严重的C2、C3型肱骨髁间骨折中推广使用。     

Tensile behavior of cortical bone: dependence of organic matrix material properties on bone mineral content

A porous composite model is developed to analyze the tensile mechanical properties of cortical bone. The effects of microporosity (volksman's canals, osteocyte lacunae) on the mechanical properties of bone tissue are taken into account. A simple shear lag theory, wherein tensile loads are transferred between overlapped mineral platelets by shearing of the organic matrix, is used to model the reinforcement provided by mineral platelets. It is assumed that the organic matrix is elastic in tension and elastic-perfectly plastic in shear until it fails. When organic matrix shear stresses at the ends of mineral platelets reach their yield values, the stress-strain curve of bone tissue starts to deviate from linear behavior. This is referred as the microscopic yield point. At the point where the stress-strain behavior of bone shows a sharp curvature, the organic phase reaches its shear yield stress value over the entire platelet. This is referred as the macroscopic yield point. It is assumed that after macroscopic yield, mineral platelets cannot contribute to the load bearing capacity of bone and that the mechanical behavior of cortical bone tissue is determined by the organic phase only. Bone fails when the principal stress of the organic matrix is reached. By assuming that mechanical properties of the organic matrix are dependent on bone mineral content below the macroscopic yield point, the model is used to predict the entire tensile mechanical behavior of cortical bone for different mineral contents. It is found that decreased shear yield stresses and organic matrix elastic moduli are required to explain the mechanical behavior of bones with lowered mineral contents. Under these conditions, the predicted values (elastic modulus, 0.002 yield stress and strain, and ultimate stress and strain) are within 15% of experimental data.     

Bone formation induced by a novel form of mechanical loading on joint tissue.

Because of insufficient mechanical loading, exposure to weightlessness in space flight reduces bone mass. In order to maintain bone mass in a weightless condition, we investigated a novel form of mechanical loading--joint loading. Since some part of gravity-induced loading to our skeletal system is absorbed by viscoelastic deformation of joint tissues, we hypothesized that deformation of joint tissues would generate fluid flow in bone and stimulate bone formation in diaphyseal cortical bone. In order to test the hypothesis, we applied directly oscillatory loading to an elbow joint of mice and conducted bone histomorphometry on the diaphysis of ulnae. Using murine femurs ex vivo, streaming potentials were measured to evaluate a fluid flow induced by joint loading. Bone histomorphometry revealed that compared to no loading control, elbow loading increased mineralizing surface, mineral apposition rate, and bone formation rate 3.2-fold, 3.0-fold, and 7.9-fold, respectively. We demonstrated that joint loading generated a streaming potential in a medullar cavity of femurs. The results support a novel mechanism, in which joint loading stimulates effectively bone formation possibly by generating fluid flow, and suggest that a supportive attachment to joints, driven passively or actively, would be useful to maintain bone mass of astronauts during an exposure to weightlessness.     

Morphologic characteristics of the Alaskan Eskimo dentition. I. Shovel-shape of incisors

As part of a comprehensive dental study of coastal and inland Alaskan Eskimos, information regarding the frequency of the shovel-shape trait in the maxillary incisors is presented. The findings are compared with the trait as found in other populations. Some degree of shovel-shape was demonstrated on all upper incisors and the semi-shovel and shovel grades were found most frequently. Marked shovel-shape was present in only about 5% of the material. These findings are in accordance with similar investigations on Eskimos. No sex difference in the shovel-shape trend was present. There was a general tendency toward a higher degree of shovel-shape in the inland group; this difference may be due to more admixture with white people along the coast. Comparing male Alaskan Eskimos with Aleuts a statistically significant lower degree of shovel-shape appeared in the central incisor in the former group. The same tendency was revealed for the lateral incisor. No difference between female Aleuts and Alaskan Eskimos could be demonstrated. Only one family studied showed a significant deviation from the others with a more marked shovel-shape. The genetics of the shovel-shape may be hard to reveal in a sample where the trait is so prevalent in the whole population as in the Alaskan Eskimos.     

Articular morphology of the proximal ulna in extant and fossil hominoids and hominins

Extant hominoids share similar elbow joint morphology, which is believed to be an adaptation for elbow stability through a wide range of pronation-supination and flexion-extension postures. Mild variations in elbow joint morphology reported among extant hominoids are often qualitative, where orangutans are described as having keeled joints, and humans and gorillas as having flatter joints. Although these differences in keeling are often linked to variation in upper limb use or loading, they have not been specifically quantified. Many of the muscles important in arboreal locomotion in hominoids (i.e., wrist and finger flexors and extensors) take their origins from the humeral epicondyles. Contractions of these muscles generate transverse forces across the elbow, which are resisted mainly by the keel of the humeroulnar joint. Therefore, species with well-developed forearm musculature, like arboreal hominoids, should have more elbow joint keeling than nonarboreal species. This paper explores the three- and two-dimensional morphology of the trochlear notch of the elbow of extant hominoids and fossil hominins and hominoids for which the locomotor habitus is still debated. As expected, the elbow articulation of habitually arboreal extant apes is more keeled than that of humans. In addition, extant knuckle-walkers are characterized by joints that are distally expanded in order to provide greater articular surface area perpendicular to the large loads incurred during terrestrial locomotion with an extended forearm. Oreopithecus is characterized by a pronounced keel of the trochlear notch and resembles Pongo and Pan. OH 36 has a morphology that is unlike that of extant species or other fossil hominins. All other hominin fossils included in this study have trochlear notches intermediate in form between Homo and Gorilla or Pan, suggesting a muscularity that is less than in African apes but greater than in humans.     

Partial humeri of two Miocene Colombian primates

Distal portions of humeri from two Miocene Colombian primates were recovered during field work in 1986. The larger IGM 183420 is very similar in size and morphology to the humerus included in the type specimen of Cebupithecia sarmientoi, recovered from La Venta in 1945 (Stirton and Savage: Serv. Geol. Nac. Bogata 7:345-356, 1951) and is assigned to this taxon. IGM 183420 presents a number of features of the humerus associated with clinging postural behaviors in living platyrrhines, including a medial epicondyle with very little dorsal angulation, a cylindrical trochlea, and a contact facet for the coronoid process of the ulna. In these and other features Cebupithecia most closely resembles the extant genus Pithecia. IGM 183512 is approximately the size of Saimiri sciureus and is very similar in morphology to the humerus of this small arboreal quadruped. The medial epicondyle is more dorsally angled, the medial lip of the trochlea is more pronounced and the capitulum is less spherical as compared to Cebupithecia. This fossil is assigned to the taxon Neosaimiri fieldsi.     

The effects of misalignment during in vivo loading of bone: Techniques to detect the proximity of objects in three-dimensional models

Theories of mechanical adaptation of bone suggest that mechanical loading causes bone formation at discrete locations within bone microstructure experiencing the greatest mechanical stress/strain. Experimental testing of such theories requires in vivo loading experiments and high-resolution finite element models to determine the distribution of mechanical stresses. Finite element models of in vivo loading experiments typically assume idealized boundary conditions with applied load perfectly oriented on the bone, however small misalignments in load orientation during an in vivo experiment are unavoidable, and potentially confound the ability of finite element models to predict locations of bone formation at the scale of micrometers. Here we demonstrate two different three-dimensional spatial correlation methods to determine the effects of misalignment in load orientation on the locations of high mechanical stress/strain in the rodent tail loading model. We find that, in cancellous bone, the locations of tissue with high stress are maintained under reasonable misalignments in load orientation (p<0.01). In cortical bone, however, angular misalignments in the dorsal direction can alter the locations of high mechanical stress, but the locations of tissue with high stress are maintained under other misalignments (p<0.01). We conclude that, when using finite element models of the rodent tail loading model, small misalignments in loading orientation do not affect the predicted locations of high mechanical stress within cancellous bone.     

The relationship between musculoskeletal stress markers and biomechanical properties of the humeral diaphysis

Musculoskeletal stress markers (MSM) at entheses and bone biomechanical properties are used in activity reconstructions. The effect of physical activity on bone biomechanical properties is well established but the relative role of physical activity on MSM is less well known. In this article, it is hypothesized that the same causal mechanisms should affect MSM development as those responsible for bone biomechanical properties. Further, there should be a correlation between MSMs and bone cross-sectional properties as both are considered to reflect physical activity. This was tested using three skeletal samples: early 20th century Finnish (Helsinki) and two medieval English (Blackgate and York) populations. Torsional/average bending rigidity (J) for four cross-sectional locations at 80, 65, 50, and 35% of humeral length from the distal end was calculated and pectoralis major, teres major, and deltoid were scored for MSM. Correlations between MSM and size-standardized J were significant for many comparisons, although they were stronger in males than in females, especially on the right side. In ANOVAs, sample was found to be a significant influence on the right side in both sexes. Using an aggregated MSM score, covariance between J and high MSM scores was again stronger in males. Covariance between J and MSM was found both at cross-sectional locations under muscle insertions and at more distant locations, demonstrating both direct and general effects of muscular loadings applied to diaphyses. Thus, the two types of skeletal markers appear to be related to similar underlying mechanical factors, but effects may also be sex- and sample-specific.     

Capitula in the Asteridae: A widespread and varied phenomenon

The presence of capitula, the head-type of inflorescences, is widespread in the Asterideae. Several families, predominantly terminal in the clade, display the tendency of maximizing reproductive output by condensing indeterminate inflorescences to the point of capitulum formation. This is accomplished by the process of halting or suppressing development of the internodes, an example of paedomorphosis of the progenesis type. This tendency is either infrequent or absent in the basal members of the Asteridae. When inflorescence condensation is present, closely related taxa often demonstrate the progression of the paedomorphosis. More examples of capitulum formation are found in the more advanced families, culminating with the Asteraceae, almost all of which display fully condensed capitula of some sort. Other phenomena are also apparent besides the basic inflorescence condensation. Edge effects are often seen, ranging from a mere crowding of the outermost flowers to the formation of additional flower types. In some taxa, inflorescence condensation continues beyond the basic capitulum form, yielding even more condensed inflorescences that then become determinate. More highly condensed inflorescences have independently evolved several times in the Asteraceae, and some tertiarily condensed inflorescences have evolved as well.     

The Effects of Prolonged Cryopreservation on the Biomechanical Properties of Bone Allografts: A Microbiological, Histological and Mechanical Study

Bone allografting is the most common form of allotransplantation in modern medicine. Bone banking is usually the major part of most tissue banks throughout the world. Several years ago, many standards of bone banking were set empirically, and have never been evaluated. One particular parameter or standard was outdating graft materials after 5 years of storage. This study was conducted to evaluate the effect of prolonged cryopreservation on the biomechanical properties of bone allografts and establish whether graft materials become contaminated during long-term storage.Proximal humeral bone allografts were obtained from the bone bank after 1, 3 and 5 years of –80°C cryopreservation. Samples of each humeral head, i.e., cartilage, subchondral bone and spongy bone were histologically examined for inter- and intra-cellular changes. A three-point mechanical bending test was used on identical pieces of cortical bone to compare fresh and cryopreserved materials. Fresh-retrieved cortical bone using identically-sized segments, served as a control. Cultures were taken from each respective sample to determine contamination or sterility.Results of both the histological and mechanical testing showed that there were no significant, qualitative histological, or quantitative mechanical differences among the samples. All the cultures were negative. Therefore, based on this study's parameters, bone allografts can safely be used after a cryopreservation period of over 5 years and should not be discarded.     

The prostacyclin/thromboxane balance is favourably shifted in Greenland Eskimos

The rare incidence of cardiovascular disease in Eskimos has been ascribed to their diet rich in eicosapentaenoic acid (EPA, C20:5n-3) and hence a possible formation of trienoic prostanoids. In this study we compare endogenous formation of prostacyclin (PGI), which is formed by the endothelial cell, and thromboxane (TXA), which is formed by platelets in 20 Eskimos and 20 age and sex matched Danish controls by measurement of the main urinary metabolites. Considerable formation of bioactive PGI3 from dietary EPA was shown in Eskimos, which was barely detectable in the controls. Furthermore synthesis of PGI2 was significantly higher in Eskimos in spite of a markedly lower arachidonate content in membrane lipids. In contrast formation of TXA2,3 was lower in Eskimos as compared to the Danish controls. We conclude, that the balance between PGI and TXA, which may regulate the interaction of platelet and vessel wall, is favourably shifted in Greenland Eskimos to an antithrombotic state.     

The position of crossing branches of the medial antebrachial cutaneous nerve during cubital tunnel surgery in humans

The posterior branch of the medial antebrachial cutaneous nerve courses in proximity to the cubital tunnel and is particularly prone to injury during ulnar nerve release at the elbow. Inadvertent injury to medial antebrachial cutaneous nerve branches during surgery can result in the formation of painful neuromas that can be misdiagnosed as recurrent disease. It is important to understand the relevant anatomy of the medial antebrachial cutaneous nerve branches during cubital tunnel surgery to avoid significant postoperative morbidity. This prospective observational anatomic study examined the position of the posterior branch of the medial antebrachial cutaneous nerve in relationship to a standard approach to the cubital tunnel in a randomly selected group of 97 patients undergoing primary surgery over a 3-year period. Medial antebrachial cutaneous nerve branches were noted to cross at or proximal to the medial humeral epicondyle 61 percent of the time at an average proximal distance of 1.8 cm. Medial antebrachial cutaneous nerve branches were noted to cross distal to the medial humeral epicondyle 100 percent of the time at an average distal distance of 3.1 cm. Understanding the general position of crossing medial antebrachial cutaneous nerve branches during ulnar nerve release at the elbow may help to prevent iatrogenic injury to this cutaneous nerve.