Weight-bearing Stress Research Articles

Site-specific bone mass differences of the lower extremities in 17-year-Old ice hockey players.

The purpose of the present study was to evaluate bone mass in the pelvis and lower extremities in young ice hockey players, and especially to investigate whether any differences are related to the type and magnitude of weight-bearing loading and muscle stress. The ice hockey group consisted of 22 boys (mean age 16.9 +/- 0.3) from three different ice hockey teams training for about 9 hours/week (mean 9.3 +/- 2.0, range 6-15). The reference group consisted of 22 boys (age 16.8 +/- 0.3) not training for more than 4 hours per week (mean 1.5 +/- 1.5, range 0-4). The groups were matched according to age, pubertal stage, weight, and height. Areal bone mineral density (BMD) was measured in total body, head, pelvis, ala ossis ilii, femoral neck, trochanter, femur diaphysis, and tibia diaphysis using dual energy X-ray absorptiometry. Isokinetic muscle strength of the quadriceps and hamstrings muscles was measured using an isokinetic dynamometer. BMDs of the total body, femoral neck, trochanter, and pelvis, but not of the head, ala ossis ilii, femur diaphysis, and tibia diaphysis, were found to be significantly higher (P < 0.05) in the ice hockey group. Muscle strength of the quadriceps muscles was also found to be significantly higher among the ice hockey players, but this greater muscle strength did not predict any BMD site significantly. However, in the reference group, there was a general strong relationship between muscle strength and BMD. This study has demonstrated significantly higher BMD in adolescent ice hockey players than in referents on a low or moderate level of physical activity. The differences seem to be site-specific and may be related to the type and magnitude of loading acting on each site, during off-season training and preferentially during ice hockey. The nonsignificant differences in BMD of the tibia and femur diaphyses may reflect that the compressive forces acting on these sites during ice hockey are not of sufficient magnitude to influence BMD. High muscle stress in itself, without weight-bearing loading, acting on the ala ossis ilii in adolescent boys does not seem to increase BMD, and an increased muscle strength does not predict BMD in highly trained adolescent boys.

Kangaroo rat bone compared to white rat bone after short-term disuse and exercise.

Kangaroo rats (Dipodomys ordii) were used to study the effects of confinement on mechanical properties of bone with a long range objective of proposing an alternative to the white rat model for the study of disuse osteoporosis. Kangaroo rats exhibit bipedal locomotion, which subjects their limbs to substantial accelerative forces in addition to the normal stress of weight bearing. We subjected groups of kangaroo rats and white rats (Rattus norvegicus) to one of two confinement treatments or to an exercise regime; animals were exercised at a rate calculated to replicate their (respective) daily exercise patterns. White laboratory rats were used as the comparison because they are currently the accepted model used in the study of disuse osteoporosis. After 6 weeks of treatment, rats were killed and the long bones of their hind limbs were tested mechanically and examined for histomorphometric changes. We found that kangaroo rats held in confinement had less ash content in their hind limbs than exercised kangaroo rats. In general, treated kangaroo rats showed morphometric and mechanical bone deterioration compared to controls and exercised kangaroo rats appeared to have slightly "stronger" bones than confined animals. White rats exhibited no significant differences between treatments. These preliminary results suggest that kangaroo rats may be an effective model in the study of disuse osteoporosis.

Fracture of an alumina ceramic head in total hip arthroplasty

The authors have experienced a fracture in the ceramic head in a total hip arthroplasty in three cases. Two of these were comminuted and the other was a hair-line fissure. A foreign body, perhaps from the operation, existed between the neck of the stem and the head in two cases (one in a comminuted fracture and the other in the fissure fracture). The other case had no foreign body, and, judging from the serial radiographs, the fracture was probably caused by weight-bearing stress. Care must be taken during operation to avoid interposing any foreign body in the modular ceramic head total hip arthroplasty, and the weight-bearing stress factor must be considered as an indication for a ceramic head fracture in young active patients.

Radiographic and Scintigraphic Features of Modeling and Remodeling in the Heterotopic Skeleton of Patients Who Have Fibrodysplasia Ossificans Progressiva

To characterize the radiographic and scintigraphic features of modeling and remodeling in the heterotopic skeleton of patients who have fibrodysplasia ossificans progressiva, radiographs from 47 patients and radionuclide bone scans from 12 of those patients, all of whom had a confirmed diagnosis of the disease, were reviewed. A wide range of normal bone modeling and remodeling features was seen in the heterotopic skeleton of all but the youngest two (age, 1 year) of the 47 patients. Characteristic features of normal bone modeling identified on radiographs of the heterotopic skeleton included: (a) the development of tubular and flat bones with mature cortical and trabecular organization; (b) the presence of well defined cortical-endosteal borders enclosing medullary canals; and (c) the presence of metaphyseal funnelization in isolated ossicles or at sites of synostoses. Characteristic features of normal bone remodeling identified on radiographs of the heterotopic skeleton included: (a) the response of heterotopic bone to weight bearing stress with osteosclerosis of use and osteopenia of disuse, and (b) the resistance of heterotopic bone to fatigue failure with the absence of pathologic fractures and stress fractures. Radionuclide bone scans in 12 patients showed that remodeling of mature heterotopic bone occurred at a rate consistent with that of mature normotopic bone. This study documents the radiographic and scintigraphic features of a heterotopic skeletal system in 47 patients who have fibrodysplasia ossificans progressiva. These data provide additional support for the hypothesis that the genetic defect leading to the formation of a heterotopic skeleton involves normal skeletal morphogenesis at heterotopic sites.

The Effects of Nonswimming Water Exercises on Older Adults

Exercise in a water medium reduces weight-bearing stresses on the skeletal joints, which may be advantageous for older individuals needing rehabilitation. The purpose of this study was to determine the effects of nonswimming exercises on muscle endurance, % body fat, and aerobic work capacity of an older adult population. Twelve subjects were in an exercise group (10 females and two males), and eight were in a control group (five females and three males). The mean ages of the groups were 65 (+/- 5.29) years and 56 (+/- 6.78) years, respectively. Before and after 12 weeks of training, subjects were measured three times weekly for resting heart rate, maximum heart rate, VO2 max, body composition, and work capacity in water. A general linear model ANCOVA was used with age as the covariate. The exercise group improved significantly (p < .05) on all dependent variables examined except body composition after 12 weeks. However, the control group experienced no significant changes on any variable over this period. In the comparisons between groups, the exercise group significantly surpassed the control group on all variables except body composition, where neither group experienced change. Nonswimming exercises appear to be a viable and effective means to improve cardiorespiratory function and physical work capacity of the elderly.

The hallux sesamoids revisited.

The hallux sesamoids are vulnerable to significant injury and weight-bearing stress in both the athlete and the nonathlete. Unfortunately, they are often dismissed as inconsequential accessory bones. The historical significance, embryology, anatomy, and physiology of the sesamoids and the salient features of both traumatic and nontraumatic pathologic conditions affecting these structures are presented. Because the sesamoids can be responsible for prolonged disabling foot pain and discomfort, it is important for both clinician and radiologist to pay attention to these bones and recognize the early signs of abnormality.

Relation between Body Size and Bone Mineral Density with special reference to Sex Hormones and Calcium Regulating Hormones in Elderly Females.

We studied the relation between body size and bone mineral density in elderly females. The study included a total of 93 ambulatory females aged over 60 years. They were divided into 3 groups according to their body mass index (BMI; kg/m2): slender group with BMI less than 20 (n = 28), normal group with BMI of 20 to 24.9 (n = 43) and obese group with BMI greater than or equal to 25 (n = 22). Fracture incidence, bone mineral density, calcium regulating hormones and steroid hormones were studied in an intergroup comparative manner. The incidence of vertebral fracture was found to be negatively correlated with BMI (the incidences of vertebral fracture in slender, normal and obese were 78.6, 48.8 and 22.7%, respectively) and bone mineral density was also BMI-related (0.390 +/- 0.016, 0.456 +/- 0.015 and 0.493 +/- 0.018 g/cm2, respectively: p less than 0.01 in ANOVA; mean +/- SE). The number of years after menopause was shorter in patients with a higher BMI. There was no intergroup difference in serum levels of PTH, vitamin D and estrogens. On the other hand, serum levels of calcitonin, DHEA, DHEAS, delta-4 androstenedione and testosterone were found to be higher in subjects with a higher BMI. From the present results, it seems that bone mineral density is supported not only by weight-bearing stress upon bone, but also by serum levels of calcitonin and androgens in obese females.

Bone density in myelomeningocele: the effects of ambulatory status and other factors.

Measurements were made of distal radius, mid-radius, tibia and metatarsal bone-density of 80 patients with myelomeningocele (17 thoracic, six L1/L2, 13 L3, 30 L4, 14 L5/sacral). For the upper extremity the bone density primarily was low in the thoracic patients, but in the tibia and metatarsal it showed a more linear correlation with neurological levels. The effect of age was highly significant at all sites; after controlling for this, the neurological level was a significant determinant of bone density at all sites, and this effect was greater in older children. Patients with impaired ambulation had decreased bone-density in the distal radius, tibia and metatarsal, but not in the mid-radius. Race had no significant effect on density after accounting for differences in neurological level. Weight for height and multiple fractures did not correlate with bone density. Although ambulatory status (weight-bearing stresses) and neurological status (muscle stresses) are both important factors in bone density, this study suggests that the latter is a more important determinant.

Beobachtungen über den Einfluß von Druckbelastung und Bewegung auf die Gelenke am Modell arthrosedisponierter Mäuse

Mice of the C 57 Black and other strains are genetically predisposed to develop osteoarthritis. Upon histological examination of the knee-joint in particular, which is the joint subjected to the greatest weight-bearing stresses in the mouse, characteristic alterations can be recognized.

The Current Status of Free Vascularized Bone Grafts

In the last decade, free vascularized bone transfer has become an established technique, with success rates above 90 per cent reported in most series. These operations have special application for those situations in which the bone defect is large, the recipient bed is poorly vascularized, and there is an associated soft tissue deficiency. The donor sites now include the fibula, iliac crest, rib, metatarsal, radius, and scapula. Because this is a rapidly expanding field of surgical endeavor, much of the work is unpublished and information in some instances has been obtained necessarily from recent clinical meetings and by personal communication with surgeons. Our experience of 41 bone transfers, using the fibula and the iliac crest as the donor grafts, over a 9-year period has been presented. In general, the fibula is recommended for the reconstruction of a long bone. In the lower extremity it should be placed within the medullary cavity of the recipient bone ends so as to be sited in the line of the weight-bearing stress. The iliac osteocutaneous graft is ideal for reconstructing the mandible and other curved bones but can be used also for shorter defects of the tibia. With appropriate osteotomies the curvature of this bone can be increased or straightened to satisfy the requirements of the recipient site. Stress fracture of a long graft is not uncommon in the lower extremity, especially in adults. Nevertheless, this is followed usually by rapid formation of callus at the fracture site and hypertrophy of the bone. The use of angiography, replica bone models, and trial operations on cadavers is recommended in planning. Operative refinements include a simpler dissection of the fibula with a thinner sleeve of muscle; shaping the iliac bone graft while it is still attached at the donor site; and the suture of vein grafts to the bone graft on a side table when the pedicle is too short. Finally, it must be remembered that these are still relatively sophisticated procedures that place demands on personnel and hospital routine. They do not replace conventional bone grafting techniques but offer an alternative solution for difficult situations (Fig. 19). John Hunter stated, "A surgeon must approach the victim of his operation with a sacred dread and reluctance." Although a century has passed this is still a sage message.

The Influence of Early Weight-bearing on Experimental Total Hip Arthroplasties in Dogs

The bone-cement interface is an area of concern in the long-term fixation of endoprostheses. The effect of early weight-bearing on the interface has been discussed as an important parameter influencing the characteristics of the interface. In this study, a total hip arthroplasty was performed in two groups of six dogs each. One group was allowed immediate weight-bearing, while in the other, a knee disarticulation amputation was done to prevent weight-bearing. Three animals of each group were killed at three months and three of each group at six months, and a histological study of the interface was done. No morphologic difference was observed between weight-bearing and nonweight-bearing animals in the interface area. Endosteal bone remodeling occurred regardless of weight-bearing stresses. A fibrous membrane was found between the cement and the endosteal surface of the femur, and membrane thickness was similar in all animals. The membrane between the cement and acetabular bone, however, was consistently thicker. Quantitative studies revealed increased femoral cortical bone resorption in the nonweight-bearing animals.

Aseptic loosening of cement-anchored total hip replacements.

The special conditions contributing to the loosening of 61 hip prostheses were studied and compared with 325 clinical and roentgenologically intact total hip replacements. The loosening rate rose sharply after the 6th postoperative year. One third of the artificial joints examined showed signs of loosening after the 9th year. The average loosening rate was 15.8% after 5.8 years. The condition of the bony bed apparently plays an important role, both qualitatively and quantitatively, in the success of the implant. The operative procedure is of equal importance. Deep fraising of the acetabulum, removal of insufficient amounts of cancellous bone from the proximal femur and inadequate embedding of the prosthesis stem, implantation of the stem in varus, and the use of long-neck femoral head prostheses are all factors which increase the risk of loosening. Ultimately, it is the sum of these loosening factors including the biological reaction of the tissue to the biomechanical and biochemically active foreign body which, depending on the period of influence, leads to prosthesis loosening. It is imperative that the patient's lifestyle be adjusted accordingly since external weight-bearing stress also affects durability of the prosthesis.

Treatment of tibial osteomyelitic defects and infected pseudarthroses by the Huntington fibular transference operation.

The Huntington fibular transference operation was done in three patients with tibial defects resulting from osteomyelitis and in three patients with infected pseudarthroses. It has proved to be an ideal procedure when the local condition of either skin or bone, or both, is not suitable for conventional bone-grafting operations. The fibula, transferred as a pedicle graft, hypertrophies under weight-bearing stresses, fixing the tibial fragments and stimulating osteogenesis. The procedure is carried out in two stages and bypasses the site of infection. It does not carry the risk of causing a flare-up of infection and it is most suitable for young patients.

Growth rates of epiphyseal plates in normal kittens and in kittens fed excess vitamin A: A fluorescent labelling and histological study

Abstract The growth and structure of epiphyseal plates was studied in normal kittens, and in kittens given an excess of vitamin A for 7 days prior to necropsy. Growth measurements were made on 10 different epiphyseal plates from each animal by means of in vivo labelling with a fluorescentdye. It was found that the growth of all plates was retarded in kittens which had received an excess of vitamin A. The absolute retardation of growth of each plate was directly proportional to its normal rate of growth as assessed in the control animals. The opposite limbs of each kitten were used for the study of histopathological changes and the measurement of various cellular parameters. Epiphyseal plates from the test animals were reduced in depth, contained fewer chondrocytes arranged in shorter, irregular columns and the hypertrophic cells were smaller. The cartilaginous matrix exhibited a diffuse loss of basophilia and of metachromasia, and coarse fibrillation. Measurements of growth rate and various cellular parameters were used to calculate the rate of cell formation per column and the average cell life span in epiphyseal plates from the control animals. Owing to the rapid development of pathological changes upsetting the state of dynamic equilibrium in the test plates, similar estimations in these would not have been valid. However, arguments are presented to suggest that an excess of vitamin A retards the growth of epiphyseal plates by affecting the rate of formation of new chondrocytes and, either directly or indirectly, the maximum size reached by the chondrocytes in the hypertrophic cell zone. It was further concluded that, although differential susceptibility of certain epiphyseal plates to an excess of vitamin A has been reported in kittens dosed for longer periods, it is most likely that vitamin A primarily affects epiphyseal plates in proportion to their normal rates of growth. With increasing time secondary factors probably act on the abnormal plates, accounting for differences in the severity of lesions exhibited by them. Reasons are put forward to suggest that the stress of weight bearing may well be the most important factor involved in this process.

The hand in Paget's disease (osteitis deformans).

Abstract The literature relating to involvement of the hand in Paget's disease is reviewed. Eleven patients in whom 18 hands (38 bones) were affected by Paget's disease are presented and the radiological findings described and illustrated. The following conclusions are drawn: (1) The incidence of hand involvement is almost certainly greater than generally accepted. Absence of associated clinical abnormality, leading to infrequent radiological examination, and failure to examine the hand in postmortem studies are two reasons for this lack of appreciation. (2) Although the radiological features of Paget's disease in the hand do not differ essentially from those found elsewhere, there appears to be a preponderance of the sclerotic type of lesion, frequently of an amorphous character. The disease is modified by the relatively small size of the bones involved and by the absence of weight-bearing stresses.

The shape of vertebral bodies and femoral necks in relation to activity.

The shape of children's bones is affected by the stress of muscular activity and weight-bearing. In children unable to walk, Gooding and Neuhauser (6) described increased height of the vertebral bodies, while others (1, 9–11, 13) reported coxa valga. Girdany and Danowski (5) described both features in children with advanced muscular dystrophy. The purpose of the present study has been to quantitate the above features and assess their probable relationship to physical activity in a group of mentally retarded children. Material and Methods One of us (W. A. Z.) selected a group of physically inactive mentally retarded children and matched them as closely as possible with physically active mentally retarded children of the same age. For the purposes of this study, anteroposterior and lateral films of the lumbar spine and anteroposterior films of the pelvis were obtained in 129 patients aged three to eighteen years. Lateral radiographs of the pelvis allowed an approximate calculation of the degree of ante version of the femoral neck in 55 patients. Measurements were made by one of us (C. S. H.) prior to any knowledge of the clinical diagnosis or degree of physical activity of these children. There was no concern about the possible genetic effects of the x radiation since none of these patients are expected to reproduce. All films were taken at a standard 40-inch distance, since available equipment did not allow a greater tube-film distance. Geometric distortion thus was present, yet constant. Since the retarded patients were unable to co-operate and difficult to position, true lateral films of the spine and true anatomical positioning of the extremities were not always obtained. Diameters of each lumbar vertebral body were measured in both anteroposterior and lateral projections. In the lateral view, the superoinferior diameter was measured midway between the anterior and posterior margins of the vertebral body, except in a few cases where the vertebral plates “peaked” posterior to this point; in these cases, the maximum measurement was used. The anteroposterior diameter was measured midway between and parallel to the superior and inferior vertebral plates. When necessary, approximate correction for angulation in the lateral film was made, as shown in Figures 1, A and B, allowing an accuracy within 1 mm of the true figure. The ratio of Superoinferior Diameter/ Anteroposterior Diameter provided a height index (H.I.) for each vertebral body, calculated to two decimal places. (For simplicity, in the accompanying figures this ratio is shown to only one decimal point.) The mean height index was then obtained from the average of the five lumbar vertebrae. The angle between the femoral neck and shaft was measured at the intersection of a line drawn through the axis of the femoral shaft and another line through the axis of the femoral neck. If the femoral head was at all eccentric in position, this line did not pass through the center of the femoral head.

METAPHYSEAL AND PHYSEAL INJURIES IN CHILDREN WITH SPINA BIFIDA AND MENINGOMYELOCELES.

METAPHYSEAL AND PHYSEAL INJURIES IN CHILDREN WITH SPINA BIFIDA AND MENINGOMYELOCELESMICHAEL T. GYEPES, M.D., DAVID H. NEWBERN, M.D. and EDWARD B. D. NEUHAUSER, M.D.Audio Available | Share

Bilateral hereditary micro-epiphysial dysplasia of the hips.

1. A family is described of which several members in four generations suffered epiphysial growth disturbances of an unusual kind in the capital epiphyses of the femur, with shortness of stature. 2. This disorder forms one of a group of epiphysial growth disturbances which embraces several recognised disorders, whose effects on the epiphyses vary in severity. They may occur sporadically or they may be inherited as recessive or dominant characters. 3. Differentiation depends on the behaviour of the joint line–in other words, whether the epiphysis starts to show defects through inability to sustain the stress of weight bearing. In the most serious cases the picture is that of Morquio-Brailsford's disease; when the changes are less severe the appearance may be that of bilateral Perthes' disease. Differential diagnosis is no longer possible in later life, because the ultimate condition of the defective femoral heads is the same. Only in the hereditary cases is one able, by studying the capital epiphyses of the hip in childhood, to differentiate between the changes like those of Perthes' disease on the one hand, and micro-epiphysial dysplasia without necrosis on the other.

Important aspects in the roentgen study of the normal lumbosacral spine.

To discuss those aspects of the normal lumbosacral spine which may be pertinent to the subject of low backache is a particularly difficult assignment. The more usual aspects are familiar to mature radiologists; yet the normal is far more difficult to describe than the abnormal. A review of fundamentals, however, serves a useful purpose at all times. It would seem that those aspects which are most important in this respect are, first, abnormalities in development and, second, the results of the weight-bearing stresses and strain which occur with growth and development, giving rise to aberrations in alignment. Developmental Aspects Embryologically, the vertebral column develops in three stages: the membranous, the cartilaginous, and the ossific. In the membranous stage (1) the axial skeleton first differentiates from the mesenchyme, most of which occurs in serially arranged pairs of mesodermal segments designated as sclerotomes. The sclerotomes migrate to lie in paired segmental masses alongside the notochord (Fig. 1). Each sclerotome differentiates into a compact caudal portion and a less dense cranial half. At alternate segments there is an intersegmental artery between a less dense and a compact portion. The denser caudal part of each sclerotome mass then unites with the looser cranial half and thus forms the substance of the definitive vertebra. The intervertebral disk differentiates from the denser caudal region. This so-called membranous vertebral column is succeeded at about the fourth week of fetal life by the cartilaginous vertebral column. Two cartilaginous centers appear on either side of the notochord and rapidly extend around it, thereby forming the bodies of the cartilaginous vertebrae (Fig. 2). Second pairs of cartilaginous foci appear in the lateral parts of the vertebral arch and extend backward on either side of the neural tube to form the cartilaginous vertebral arch. Still different cartilaginous centers appear for each costal arch. An aberration in the cartilaginous stage, of development, with persistence of a notochord remnant, produces the so-called butterfly hemivertebra (Fig. 3). During the cartilaginous stage the notochord is progressively compressed into the central regions of the dense intervertebral disks. Eventually it disappears completely except as the nucleus pulposus of the intervertebral cartilage. The intersegmental artery persists as a narrow channeled anterior portal into the central portion of the vertebral body (Fig. 4). This appearance of the intersegmental artery produces an anterior notching of the vertebral bodies centrally, which may persist into adult life. Such persistence is probably without pathologic significance. The anterior and posterior longitudinal spinal ligaments develop during the cartilaginous stage.

The Self-Locking Metal Hip Prosthesis

Great judgment should be exercised in the selection of patients for replacement of the femoral head and a careful postoperative program should be planned. The importance of partial weight-bearing for a period of at least six months should be emphasized, with a gradual increase as roentgenograms show the reaction of bone about the prosthesis. New-bone formation takes place within the fenestrations of the prosthesis. Once this has occurred, the stem cannot be removed without chiseling away the new bone. The prosthesis becomes, literally, self-locking. It is very interesting to see, roentgenographically, the increasing density of bone in and under the prosthesis in the stress-bearing locations. If a prosthesis is to last indefinitely, it must be constructed in such a way that stress is distributed so as to produce a dynamic reaction, in accordance with Wolff's law. In this way, there gradually occurs a thickening of bone about the prosthesis enabling it to carry the normal load of weight and stress. The prosthesis becomes a part of the living bone. Five years ago a preliminary report was made of our experience with a self-locking Vitallium prosthesis in thirty-three patiensts2. The present report reviews the same experience in 153 patients and in 159 operations during a period of six years. There have been no fractures of the bone in applying the prosthesis, and no dislocations of the hip have occurred during the operation. Apparently Vitallium is insert in the tissues, and it is possible that the prosthesis may last indefinitely. Patients are made to understand that no artificial replacement can be expected to function as well as the normal hip and are urged to be careful. They are advised to always carry a cane or to use a light support. An attempt is being made to follow all patients. Time has already shown conclusively that transplanted cancellous bone in the medullary canal undergoes metaplastic changes and that the bone becomes progressively denser in the areas of stress. Time has also shown, as was anticipated, that there is hyperplasia of bone in, under, and about the prosthesis when weight-bearing is properly applied. Excessive weight-bearing stress or too short a stem results in pressure necrosis with a loose, clicking prosthesis and pain. With the stimulating stress of gradual weight-bearing, areas of increased density of bone appear about the prosthesis consistent with known mechanical and engineering principles. When patients have been properly selected and when operation has been correctly performed, and postoperative follow-up care has been conscientiously carried out, this prosthesis appears to become a part of the femur and to carry the normal stress load of weight-bearing with minimal degenerative changes and with minimal pain. The results so far are encouraging, and the increasing number of patients bears witness to growing confidence in the procedure. Final results can be known and a thorough evaluation of the method can be made only after many years of experience.