Metacarpal synostosis: a simple classification and a new treatment technique

The current classification of metacarpal synostosis is based on the extent of the synostosis. The authors propose a new classification that takes into account the shape of the metacarpal bones, the curvature of the epiphysis, and the discrepancy in length between the two bones. This classification provides better guidelines for the correction of all components of the deformity. The classification is based on the authors' observations of and experience with 36 cases of metacarpal synostosis; 13 of the deformities were surgically corrected. The I-shaped deformity, whether with distinct (type d) or fused (type f) metacarpophalangeal joints, does not require surgical correction. The U-shaped deformity has parallel epiphysis and does not require surgery unless the two metacarpals are asymmetrical in length (type a) or tightly fused (type t); in these cases, simple lengthening or widening of the space with a bone graft is sufficient. Y-shaped synostosis should be separated whether the branches are symmetrical or asymmetrical, the latter having one branch shorter than the other. Because the epiphyses are already divergent, simple separation does not effectively correct Y-shaped synostosis. The authors propose an osteotomy to isolate a trapezoidal segment of bone from the bifurcation. The isolated bone segment is then reversed in the proximal-distal direction to provide a "plateau" upon which the two distal metacarpals can be realigned. Two cases of Ys (symmetrical) synostosis were successfully treated with this technique; one case of Ya (asymmetrical) synostosis also required distraction lengthening of the shorter metacarpal to achieve an excellent result. One of the most difficult types of metacarpal synostosis to treat is k-shaped synostosis, observed only between the fourth and fifth metacarpals; in this type, the head of the short fifth metacarpal abuts the metaphysis of the fourth. Osteotomy and distraction lengthening provide predictable results for correction of this deformity. The authors suggest that k-shaped synostosis might represent a late evolution of untreated Ua synostosis.     

Mineral saturation, ossification and synostosis of the hand bones in adolescents and youth]

The results on X-ray densitometric studies of the hand bones in adolescent and young people at the age of 10--17 years (369 persons in all) are presented in the work. Processes of mineralization, ossification and synostosis, as the investigation has demonstrated, are closely connected with each other. From the beginning of ossification in the pisiform and sesamoid bones of the first metacarpophalageal joint (11--12 years of age) up to the completion of synostosis in short tubular bones of the hand (15--16 years of age), a decrease of mineral salts is noted in osseous tissue. Hence, accumulation of mineral salts in skeleton of children and adolescent persons does not occur smoothly, but rather distinctly reflects those functional changes which take place in the adolescent organism when the genital glands begin their increased activity.     

Natural markers in bone growth

Three features in the long bones, shown by radiograms, have been used as markers for the study of bone growth.

• (I) Transverse lines of arrested growth. Radiograms of six long limb bones from 1,576 individuals were investigated for clearness and persistence of these lines. Both ends of tibia and fibula showed very high frequency of suitable lines for markers, possibly also the distal end of femur and radius.
• (II) Notches in the base of second and fifth metacarpal bones. Measurements of growth from apex of the basal notch to the ends of the shaft were performed on serial hand radiograms. The proportion of growth from distal and basal ends averaged 87:13 in the second and 80:20 in the fifth metacarpal bones.
• (III) Nutrient canals. The initial point of ossification was determined by a prolongation of the nutrient canal intersecting the central axis of the medullary cavity. The proportion of growth from that point to distal and basal ends of the shaft averaged 68:32 and 64:36 for the second and the fifth metacarpal bones, respectively. These values are significantly different from the measurements obtained from the notches.

     

Mechanisms of changes in the human spinal column in response to static and dynamic axial mechanical loading

The purpose of this study was to analyze the characteristics of the reaction of the human spinal column to axial static and dynamic loading. Segments of human column from dorsal vertebra XI to lumber vertebra III were exposed to axial static (20 mm/min) and dynamic (200 and 500 mm/min) loading. The measured variables included the load value, whole segment deformation, deformation of the anterior surfaces of intervertebral disk of Th_XI–Th_XII and dorsal vertebra XII, and acoustic emission signals (indicator of spongy bone microdestruction). It was found that the rate of increase in body deformation is lower than that in the intervertebral disk deformation and that the central parts of the spinal end plate compress greater than the peripheral parts. This difference was larger during static loading than that during dynamic loading. To produce the same deformation of a spinal segment due to dynamic loading as that due to static one, it is necessary to overcome a stronger resistance of a greater number of trabecular bones than that due to static loading. Therefore, it can be concluded that, first, the value of dynamic loading causing the same segment compression should be higher than the value of static loading, and the main practical significance here is that the dynamic strength of the column is markedly higher than the static one; second, spinal hardness during impact is higher than that under the static condition; and, third, the same degree of deformation should result in a larger volume of microdestructions in the case of dynamic loading than that in the case of static loading, which is evidenced by a significant difference in the number of AE signals accumulated prior to fracture. The number of AE signals is 444.2 ± 308.2 and 85.0 ± 36.6 in the case of dynamic and static loading, respectively (p < 0.05 according to Student’s t test).     

Bilateral asymmetry in bone measurements of the hand and lateral hand dominance

Two hundred thirty–five (235) normal male participants of the Baltimore Longitudinal Study were classified as right handed, left handed, and ambidextrous on the basis of their grip–strength performance. Their left and right hands were also radiographed and the measurements of the second metacarpal bones were evaluated on the basis of hand dominance. The results indicated that, as a rule, the right hand measurements are higher than those of the left hand, regardless of hand dominance. The bilateral differences in total width, length, total area and cortical area are significant among the right hand dominant and nonsignificant among the left hand dominant. Regardless off hand dominance the bilateral differences in medullary width are nonsignificant. These results suggest an inherent tendency of the right second metacarpal to have more bone than the left regardless of hand dominance. Differential stress due to hand dominance will increase the bilateral difference in the right handed and reduce it in the left handed.     

On how the periosteal bone of the delphinid humerus becomes cancellous: ontogeny of a histological specialization

In cetaceans, the bones of the flippers lack a free medullary cavity and have a cancellous texture, with compact cortices reduced or absent. The present work discusses the ontogenetic basis of these characters in terms of the ontogeny of the structure and textural bone compactness (TBC) of the humeral diaphysis in a growth series of common dolphins (Delphinus delphis). The texture of the primary periosteal deposits is compact; soon after their accretion, the deposits undergo an extensive erosion that turns them into a cancellous tissue. A diffuse endosteal front of resorption expands in parallel with the growth of the cortex and acts as small units scattered within the cortices. Starting soon after birth and continuing throughout the life of the animals, the compactness of the periosteal cortex decreases at both general and local levels. This trend correlates strongly with the increase in size of the diaphyseal section and reflects the fact that relatively more bone is eroded than deposited during growth in the cancellous parts of the cortex. In the broad sense, this is basically an osteoporotic process, which is not identical, however, to senile or disuse osteoporoses.     

Morphologic features of the structure of the hand bones of young volley ball players

By means of roentgenography method with subsequent roentgenogramometry and roentgenodensitometry, morphological peculiarities of structure and mineralization of the hand bones in sportsmen-volley-ball players and in schoolchildren who do not go in for sports, at the age of 14-19 years have been studied. Systematic training in volley-ball produces certain increase in dimentions of the hand bones, prolongation of their synostosis time, intensification in development of the sesamoid bones and increasing amount of mineral salts in their bones.     

Hand dominance and bilateral asymmetry in the structure of the second metacarpal

Bilateral asymmetry in the structure of the second metacarpal was examined in relation to functional hand dominance in a large, clinically nonselected, healthy population sample from the Baltimore Longitudinal Study of Aging. Bilateral bone measurements were made from anteroposterior hand radiographs of a total of 992 individuals, 609 males and 383 females, with an age range of 19–94 years. Hand dominance was determined on the basis of personal impression. Total width and medullary width at the midshaft of the second metacarpal were measured to 0.05 mm using a Helios caliper. These two measurements were used to derive cortical thickness, cortical bone area, periosteal (total) area, medullary area, percent cortical area, and the second moment of area in the mediolateral plane. In both right and left-handed individuals, statistically significant side differences were found in the calculated bone areas and the second moment of area, with the dominant hand being larger. Cortical thickness did not show significant side-related differences for either handedness. These results show that functional handedness leads to periosteal and endosteal expansion of the second metacarpal cortex on the dominant side, increasing bone strength without increasing cortical thickness. This is the first time this pattern of asymmetry has been reported in left-handers as well as right-handers. Our results argue for the primacy of environmental (mechanical) effects in determining bilateral asymmetry of limb bone structural properties. © 1994 Wiley-Liss, Inc.     

Effects of dynamic loading on solute transport through the human cartilage endplate

Nutrient and metabolite transport through the cartilage endplate (CEP) is important for maintaining proper disc nutrition, but the mechanisms of solute transport remain unclear. One unresolved issue is the role of dynamic loading. In comparison to static loading, dynamic loading is thought to enhance transport by increasing convection. However, the CEP has a high resistance to fluid flow, which could limit solute convection. Here we measure solute transport through site-matched cadaveric human lumbar CEP tissues under static vs. dynamic loading, and we determine how the degree of transport enhancement from dynamic loading depends on CEP porosity and solute size. We found that dynamic loading significantly increased small and large solute transport through the CEP: on average, dynamic loading increased the transport of sodium fluorescein (376 Da) by a factor of 1.85 ± 0.64 and the transport of a large dextran (4000 Da) by a factor of 4.97 ± 3.05. Importantly, CEP porosity (0.65 ± 0.07; range: 0.47–0.76) strongly influenced the degree of transport enhancement. Specifically, for both solutes, transport enhancement was greater for CEPs with low porosity than for CEPs with high porosity. This is because the CEPs with low porosity were susceptible to larger improvements in fluid flow under dynamic loading. The CEP becomes less porous and less hydrated with aging and as disc degeneration progresses. Together, these findings suggest that as those changes occur, dynamic loading has a greater effect on solute transport through the CEP compared to static loading, and thus may play a larger role in disc nutrition.     

Morphometric dimensions of metacarpal bones in the population structure analysis (island of Krk, Croatia)

The population structure analysis by means of the osteometric dimensions of metacarpal bones in the population groups of the northern Adriatic island of Krk, Croatia was performed. The sample consisted of randomly sampled adult islanders (94 males and 79 females) aged from 18 to 85 years from six villages of the island of Krk. "Biological distances" were estimated by the Mahalanobis D2 analysis for bone length (L), total diaphysis width (T) and medullary canal width (M) dimensions of the second left metacarpal bone. Analysis of the osteometric dimensions of metacarpal bones as a measure of biological distance between population groups of the island of Krk indicated bio-cultural and socio-cultural events, rather than geographical distances, to be the primary determinants of anthropogenetic structure of today's population groups of the island.     

Morphofunctional changes in the long tubular bones of animals which have developed while readapting after physical loads

The investigation has been performed on 120 white male rats of Wistar line. By means of the morphometry, electron microscopy and chemical methods dynamics of readaptive changes have been studied in long tubular bones during the period, when the effect of physical loadings both of dynamic and static character and of various intensity has been stopped, up to the old periods of the animals' life. Readaptation after moderate dynamic and static loadings is occurring for a long time and steadily. The changes caused by static loadings are nearly completely restored in a year. Morphofunctional rearrangements of the long tubular bones in the readaptation process after moderate dynamic loadings is characterized by residual manifestations. Prolonged readaptation after intensive physical loadings does not result in a complete restoration of all the parameters studied concerning growth and skeletal development. An intensive dynamic loading produces more stable changes, that are not subjected to a complete correction even after a passive readaptation for a year. Readaptation morphofunctional rearrangements of the long tubular skeletal bones depend on conditions of the previous regimen of the motor activity.     

Reconstruction of a complex defect of the hand with two distinct segments of the scapula and a scapular fascial flap transferred as a single transplant.

To repair multiple defects of the metacarpal bones in combination with skin defects, a combined scapular free flap on a single vascular pedicle--the subscapular artery and the accompanying veins--can be used successfully. This flap includes two distinct bone segments of the lateral border of the scapula and a scapular fascial flap. Because of its long and mobile vascular pedicle, such a transplant can be used for one-stage reconstruction of the first and other metacarpal bones of the long fingers of the hand. The scapular fascial flap included in the transplant provides good functional and aesthetic results in combined injury of the skin of the hand.     

The effects of squatting while pregnant on pelvic dimensions: A computational simulation to understand childbirth

Biomechanical complications of childbirth, such as obstructed labor, are a major cause of maternal and newborn morbidity and mortality. The impact of birthing position and mobility on pelvic alignment during labor has not been adequately explored. Our objective was to use a previously developed computational model of the female pelvis to determine the effects of maternal positioning and pregnancy on pelvic alignment. We hypothesized that loading conditions during squatting and increased ligament laxity during pregnancy would expand the pelvis. We simulated dynamic joint moments experienced during a squat movement under pregnant and non-pregnant conditions while tracking relevant anatomical landmarks on the innominate bones, sacrum, and coccyx; anteroposterior and transverse diameters, pubic symphysis width and angle, pelvic areas at the inlet, mid-plane, and outlet, were calculated. Pregnant simulation conditions resulted in greater increases in most pelvic measurements – and predominantly at the outlet – than for the non-pregnant simulation. Pelvic outlet diameters in anterior-posterior and transverse directions in the final squat posture increased by 6.1 mm and 11.0 mm, respectively, for the pregnant simulation compared with only 4.1 mm and 2.6 mm for the non-pregnant; these differences were considered to be clinically meaningful. Peak increases in diameter were demonstrated during the dynamic portion of the movement, rather than the final resting position. Outcomes from our computational simulation suggest that maternal joint loading in an upright birthing position, such as squatting, could open the outlet of the birth canal and dynamic activities may generate greater pelvic mobility than the comparable static posture.     

掌骨X线测量推断身高的研究

随机选取在校健康大学生186人(男90人, 女96人, 年龄18—27岁), 拍摄双手后前位372侧X线片, 测量身高和掌骨的长与宽。通过掌骨和身高的测量, 分析掌骨各参数与身高的关系, 为人类学和法医学的身高推断积累研究资料。掌骨长与身高的相关性明显高于掌骨宽, 其中男性第2掌骨长与身高相关性最高, 其线性回归方程为Ym=1097.320+9.337X; 女性第3掌骨长与身高的相关性最高, 其线性回归方程为Yf=1016.752+9.878X。男性第2掌骨长和女性第3掌骨长与身高的相关性最高, 可分别作为推断身高的依据。     

Synostosis dynamics in human long tubular bones

More than 8,000 roentgenograms and electroroentgenograms of brachial, ulnar, radiocarpal, coxofemoral, knee, talocrural joints have been studied in persons of both sex at the age from birth up to 25 years. The synostosis degree is appreciated by the six-mark system. The roentgenological data are corroborate histologically. The method of appreciation applied makes it possible to reveal cases of initially forming synostosis long before puberty. Three stages of synostosis process are defined. The first stage--slow increase of the synostosis mark. The second--quick synostosis formation. The third--final stage. According to the stages defined, a comparative analysis of the synostosis process in all metaepiphyseal zones of all long tubular bones, peculiarities of the process depending on the sex are demonstrated. The data on the time, when the points of ossification appear, on the beginning and completion of synostosis process in all metaepiphyseal zones of the long tubular bones are presented.     

Cortical bone measurements in Turner's syndrome.

Cortical bone width measurements taken at midshaft on the second metacarpal were obtained from 156 hand X-rays of 80 karyotypically documented individuals with Turner's syndrome age 1 to 25 years. Total shaft width, medullary width, cortical width and percent cortical area were grouped by bone age and compared with normal female standards. Total width was significantly and increasingly below normal; medullary width was not consistently different from normal; cortical width was significantly lower from normal from age 14 onward, although it did rise at age 17 (adult bone age); percent cortical area was significantly below normal at ages 14 and 15, but was normal by adulthood. Values for percent cortical area did not indicate severe or widespread osteoporosis. Within the Turners sample cortical bone measurement were not significantly decreased in the presence of the XO sex chromosome constitution compared with other sex chromosome variants. Nor were the measurements decreased in the presence of positive metacarpal sign or a combination of typical Turner stigmata (web neck, low posterior hairline, shield chest). There was evidence that cortical width and percent cortical area increased significantly following estrogen treatment or spontaneous menarche.     

Carpal bones of the Chiroptera in the comparative-anatomical and functional aspects

Data on investigation of hand sceletal bones carried out in eight genera of three families of bats were subjected to comparative-anatomical and functional analysis. Quantitatively, the hand sceletal bones of Chiroptera preserve constructive pattern general for the hand of terrestrial mammalians Pentadactilus. It has rudiments of the prefirst (Pp) and the seventh (Pm) rays. The latter is situated on the volar surface of the base Mc5. Scaphoid, semilunar and central carnal bones of Chiroptera, like those of Mototremata, some Marsupialia, Insectivorona and Carnivora merge together into one large bone--os lunatum. At the same time, the hand of Chiropter is a highly specialized structure, that is evident from the presence of articular restricotrs of anterior sagging of the wrist, crests and grooves directing movements in a strictly definite plane, from fan-like spreading and bringing together the rays, from very long metacarpal bones and proximal phalanges, from reduction of distal phalangs of the 3d and 5th fingers. Thus, the hand of Chiroptera is a unique example of combination of primitive, initial for pentadactule plantigrades wrist with signs of narrow specialization resembling, to some extent, those of Ungulata; only in Ungulata those signs developed on the base of digitigrades wrist.     

Evolutionary Patterns of Bone Histology and Bone Compactness in Xenarthran Mammal Long Bones

Bone microstructure reflects physiological characteristics and has been shown to contain phylogenetic and ecological signals. Although mammalian long bone histology is receiving increasing attention, systematic examination of the main clades has not yet been performed. Here we describe the long bone microstructure of Xenarthra based on thin sections representing twenty-two species. Additionally, patterns in bone compactness of humeri and femora are investigated. The primary bone tissue of xenarthran long bones is composed of a mixture of woven, parallel-fibered and lamellar bone. The vascular canals have a longitudinal, reticular or radial orientation and are mostly arranged in an irregular manner. Concentric rows of vascular canals and laminar organization of the tissue are only found in anteater bones. The long bones of adult specimens are marked by dense Haversian bone, a feature that has been noted for most groups of mammals. In the long bones of armadillos, secondary osteons have an oblique orientation within the three-dimensional bone tissue, thus resulting in their irregular shape when the bones are sectioned transversely. Secondary remodeling is generally more extensive in large taxa than in small taxa, and this could be caused by increased loading. Lines of arrested growth are assumed to be present in all specimens, but they are restricted to the outermost layer in bones of armadillos and are often masked by secondary remodeling in large taxa. Parameters of bone compactness show a pattern in the femur that separates Cingulata and Pilosa (Folivora and Vermilingua), with cingulates having a lower compactness than pilosans. In addition, cingulates show an allometric relationship between humeral and femoral bone compactness.     

Sutural effects of fronto-occipital cranial modification

Maya adult crania from the site of Lamanai, Belize provide a retrospective means of examining growth processes in the cranial vault. The Lamanai population practiced fronto-occipital deformation which is found to be significantly associated with premature sagittal synostosis and wormian bones of the lambdoidal suture. The undeformed members of the population also exhibit an abnormally high frequency of sagittal synostosis, but a significantly lower frequency than the deformed sample. It is suggested that the deforming apparatus creates tensile forces on the sagittal suture during the peak period of growth of the parietals, and that these forces might induce an adaptive response important in producing premature sagittal synostosis. The undeformed sample may have an increased congenital risk of sagittal synostosis created by their natural brachycephalic morphology in utero. The frequency patterning of wormian bones suggests a mixture of genetic and environmental causes in which tensile forces may also play a role. © 1996 Wiley-Liss, Inc.     

Functional anatomy of the hand of Australopithecus africanus

The Sterkfontein hand bones, attributed to Australopithecus africanus, were analysed to determine potential hand function of the power grip type of this species. The metacarpus is as stable as that of modern humans, as indicated by the depth of the groove on the base of metacarpal 2, the styloid process of metacarpal 3, the base articular surface areas, and the ligament markings on the bases of the metacarpals. The flexion and rotation of metacarpal 5 might have been less than that of modern humans, due to a more marked ventral articular lip on the base. The metacarpus acts as a lever, acting in various planes. The extensor carpi ulnaris and extensor carpi radialis longus muscles were probably better developed than in modern humans. The extensor carpi radialis brevis and flexor carpi radialis muscles would probably have been as well developed as in modern humans. None of the long tendons have a mechanical disadvantage as compared to modern humans. The metacarpals have a high robusticity index. The proximal phalanges show some midshaft swelling, slightly greater curvature than in modern humans, and some side to side bowing: pongid features. The fibrous flexor sheath markings are well developed, but resemble those of modern humans rather than those of the pongids. A single middle phalanx resembles that of modern humans, and has well developed ridges for insertion of the flexor digitorum superficialis muscle. The distal phalanx of the thumb has a well developed region for insertion of the flexor pollicis longus muscle, and has a mechanical advantage over modern humans for action of this muscle at the interphalangeal joint. The features indicate that the hand of A. africanus was well adapted to powerful hand use, as in hammering, striking, chopping, scraping, and gouging actions, as well as for throwing and climbing activities.