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PubMed2004

Multislice computed tomography of the distal radius metaphysis: relationship of cortical bone structure with gender, age, osteoporotic status, and mechanical competence.

We explore the relationship of region-specific densitometric and geometry-based (cortical) parameters at the distal radial metaphysis with gender, age, and osteoporotic status, using multislice computed tomography (CT). We specifically test the hypothesis that these parameters can improve the prediction of mechanical strength of the distal radius vs bone mass (bone mineral content [BMC]). The BMC was determined in 56 forearm specimens with peripheral dual-energy X-ray absorptiometry (DXA). Trabecular and cortical density and geometric properties of the metaphyseal cortex were determined using multislice CT and proprietary image analysis software. Specimens were tested to failure in a fall simulation, maintaining the integrity of the elbow joint and hand. Women displayed significantly lower failure strength (-34%), BMC (-35%), trabecular density (-26%), and cortical area (-12%) than men. The reduction of trabecular density with age and osteoporotic status was stronger than that of cortical density or thickness. DXA explained approx 50% (r2) of the variability in bone failure loads. This proportion was slightly increased (55%) when adding geometry-based parameters. The study suggests that high-resolution tomographic measurements with current clinical imaging methodology can marginally improve the prediction of mechanical failure strength. Further efforts are required to improve spatial resolution for determining metaphyseal cortical properties clinically.

Aged↗
PubMed2004

Accuracy and precision of peripheral quantitative computed tomography measurements at the tibial metaphysis.

The ability of 29 peripheral quantitative computed tomography (pQCT) software analysis modes at defining cortical from trabecular bone at three tibial metaphyseal regions was evaluated using five cadaveric tibiae. The accuracy of pQCT was determined by comparing the bone mineral content (BMC) with the ash weight. The precision of the pQCT scanner was calculated using repeated measurements. All the analysis modes had a good accuracy when measuring total bone area and a poor accuracy when measuring cortical bone area at the proximal 5% and distal 4% regions. For trabecular bone measured at all three regions and cortical bone area measured at the proximal 10% region, the Stratec peel mode 5 was the most accurate analysis mode. Highly significant correlations (r = 0.71-0.98) and a moderate accuracy error (coefficient of variation [CV] = 5-22%) was found between ash weight and BMC when using this mode. The precision of bone mineral density (BMD) measurements was good (total, CV = 2-5%; trabecular, CV = 2-5%; cortical, CV = 4-6%). pQCT is a moderately accurate, precise method of measuring trabecular and total BMD at the tibial metaphysis. The authors recommend caution when interpreting results for cortical BMD, as cortical area measurements at the metaphyseal region are less accurate and less precise.

Adult↗
PubMed1994

Interactions of insulin-like growth factor I with dexamethasone on trabecular bone density and mineral metabolism in rats.

Glucocorticoid treatment causes osteoporosis and growth retardation in humans. Insulin-like growth factor I (IGF-I) stimulates differentiation and replication of cultured osteoblast-like cells and induces longitudinal bone growth in IGF-I-deficient rats. We investigated the influence of subcutaneously infused IGF-I on bone and mineral metabolism of male rats treated with a high dose of dexamethasone. Dexamethasone was added to the drinking water in a concentration of 1 mg/l. After 30 days of dexamethasone treatment, recombinant human IGF-I (300 micrograms/day) or solvent was infused sc by osmotic minipumps for 21 days while dexamethasone was continued. Age-matched untreated male rats served as healthy controls. Dexamethasone-treated rats lost weight. Their IGF-I levels were decreased to 36% of healthy controls. Infusion of IGF-I resulted in an increase in IGF-I serum levels (582% compared to healthy controls) and allowed some weight gain. Osteocalcin and calcitriol levels were markedly decreased in dexamethasone-treated rats and were not influenced significantly by IGF-I infusion. In contrast, IGF-I treatment restored the free calcitriol concentration (molar ratio of calcitriol to vitamin D-binding protein) towards normal. Furthermore, infusion of IGF-I partially corrected the dexamethasone-induced hyperinsulinemia. Histomorphometric analysis revealed no difference in vertebral trabecular bone density (i.e. growth-independent bone remodeling) between the three groups. In contrast, mean trabecular bone density in tibial metaphyses was increased markedly by dexamethasone, presumably due to osteoclast inhibition. Insulin-like growth factor I infusion did not significantly influence these structural metaphyseal bone parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed2006

Orthopedic complications of overweight in children and adolescents.

OBJECTIVE: Few studies have quantified the prevalence of weight-related orthopedic conditions in otherwise healthy overweight children. The goal of the present investigation was to describe the musculoskeletal consequences of pediatric overweight in a large pediatric cohort of children that included severely overweight children. METHODS: Medical charts from 227 overweight and 128 nonoverweight children and adolescents who were enrolled in pediatric clinical studies at the National Institutes of Health from 1996 to 2004 were reviewed to record pertinent orthopedic medical history and musculoskeletal complaints. Questionnaire data from 183 enrollees (146 overweight) documented difficulties with mobility. In 250, lower extremity alignment was determined by bilateral metaphyseal-diaphyseal and anatomic tibiofemoral angle measurements made from whole-body dual-energy x-ray absorptiometry scans. RESULTS: Compared with nonoverweight children, overweight children reported a greater prevalence of fractures and musculoskeletal discomfort. The most common self-reported joint complaint among those who were questioned directly was knee pain (21.4% overweight vs 16.7% nonoverweight). Overweight children reported greater impairment in mobility than did nonoverweight children (mobility score: 17.0 +/- 6.8 vs 11.6 +/- 2.8). Both metaphyseal-diaphyseal and anatomic tibiofemoral angle measurements showed greater malalignment in overweight compared with nonoverweight children. CONCLUSIONS: Reported fractures, musculoskeletal discomfort, impaired mobility, and lower extremity malalignment are more prevalent in overweight than nonoverweight children and adolescents. Because they affect the likelihood that children will engage in physical activity, orthopedic difficulties may be part of the cycle that perpetuates the accumulation of excess weight in children.

Adolescent↗
PubMed1994

Molecular cloning and expression of bone morphogenetic protein-7 in the chick epiphyseal growth plate.

Longitudinal bone growth occurs in the epiphyseal growth plate and is regulated by a network of paracrine and autocrine interactions. Bone morphogenetic proteins (BMPs) are a family of growth factors whose potent osteogenic properties suggest that they may play an important role within this network, but direct evidence for this is lacking. To address this question, a cDNA encoding chick BMP-7 was cloned from a chick embryo cDNA library. Sequence homology and evolutionary arguments strongly suggested that we had cloned the chicken BMP-7 homologue. Using a reverse transcription-PCR assay, BMP-7 expression was readily detected in bone, growth plate cartilage, brain and heart, and was just detectable in liver, skeletal muscle and adipose tissue. In contrast to the pattern of BMP-7 expression in the rat and mouse, no BMP-7 expression was detected in the chick kidney. In situ hybridization was used to locate the site of BMP-7 expression more precisely within the growth plate. BMP-7 expression was confined to hypertrophic chondrocytes adjacent to and at the tips of the metaphyseal vessels. No expression was detected in the reserve zone or in proliferating chondrocytes. These results point to a specific role for BMP-7 in the growth plate, possibly in osteoblast activation or as a chemotactic agent for the metaphyseal vessels.

Amino Acid Sequence↗
PubMed2000

High-resolution micro-computed tomography analyses of the abnormal trabecular bone structures in klotho gene mutant mice.

Inactivation mutation of the recently discovered klotho gene in mice causes a syndrome resembling aging. Manifestations include short life span, atherosclerosis, gonadal atropy, skin atropy, emphysema, ataxia and ectopic calcification. These mice also exhibit abnormally high bone density in the epiphyses of their tibiae based on X-ray and histological analyses. However, micro-structures of the trabecular bones in arbitrary two-dimensional planes or three-dimensional regions are difficult to analyze by these techniques. Therefore, we applied high resolution micro-computed tomography (microCT) to characterize the micro-structural abnormality in the trabecular bone in long bones as well as in vertebrae of four- to six-week-old klotho mutant mice. Two-dimensional microCT analyses in the mid-sagittal plane as well as three-dimensional microCT analyses indicated that the trabecular bone volume fraction measured in the proximal metaphyses of the tibiae was increased more than twofold in klotho mutant mice compared with the wild-type mice. Similarly, the trabecular bone area fraction in the mid-sagittal plane of the lumbar vertebral bodies was also increased by about 80% at the proximal and distal ends. No significant difference was observed with regard to the cortical thickness in the mid-shaft of femora between klotho mutant and wild-type mice. Three-dimensional microCT analyses also indicated that the trabecular number and thickness of the proximal metaphyses of the tibiae were increased by about 80% and 300% respectively in the klotho mutant mice, while trabecular separation was 60% less in klotho mutant mice compared with the wild-type mice. These quantitative microCT analyses indicate that the inactivation of klotho gene expression results in an increase in three-dimensional bone volume fraction, number and thickness of the trabecular bones in these mice.

Animals↗
PubMed2004

Expression of estrogen receptors and enzymes involved in sex steroid metabolism in the rat tibia during sexual maturation.

Estrogens are essential for bone mass accrual but their role before sexual maturation has remained elusive. Using in situ hybridization and immunohistochemistry, we investigated the expression of both estrogen receptor (ER) alpha and beta mRNA and protein as well as several mRNAs coding for enzymes involved in sex steroid metabolism (aromatase, type I and II 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD), steroid sulfatase (STS) and type I 5 alpha-reductase) on sections of tibial metaphyses before (1- and 4-week-old), during (7-week-old) and after (16-week-old) sexual maturation in female and male rats. ER alpha and ER beta mRNA and protein were detected in metaphyseal bone in lining cells, osteoblasts, osteoclasts and some osteocytes with no apparent differences in expression during development or between the sexes. In contrast, aromatase, type I and II 17 beta-HSD and type I 5 alpha-reductase mRNAs were first detected in osteoblasts, osteoclasts and occasionally in osteocytes from sexual maturation (7-week-old rat) and onwards. Only STS was present before sexual maturation. To study the significance of ER alpha and beta expression in bone before sexual maturation when circulating sex steroid levels are low, 26-day-old female and male rats underwent gonadectomy or 17 beta-estradiol (E(2)) supplementation (0.5 mg/21 days) during 3 weeks. Following gonadectomy, trabecular bone volume (TBV) was lower in males (P=0.03) and there was a trend towards reduction in females (P=0.057). E(2) supplementation increased tibial TBV compared with controls in both genders as assessed by Masson-Goldner staining. These data suggest that the presence of ERs in bone cells before sex maturation might be of significance for bone mass accrual. Furthermore, based on the mRNA expression of the crucial enzymes aromatase and type I 17 beta-HSD, we suggest that bone cells in the tibial metaphysis acquire the intrinsic capacity to metabolize sex steroids from sexual maturation onwards. This process may contribute to the beneficial effects of estrogen on bone mass accrual, possibly by intracrinology.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1999

Growth plate cartilage formation and resorption are differentially depressed in growth retarded uremic rats.

To characterize the modifications of growth plate in individuals with growth impairment secondary to chronic renal failure, young rats were made uremic by subtotal nephrectomy (NX) and, after 14 d, their tibial growth plates were studied and compared with those of sham-operated rats fed ad libitum (SAL) or pair-fed with NX (SPF). NX rats were growth retarded and severely uremic. Growth plate height (mean +/- SD) was much greater (P<0.05) in NX (868.4+/-85.4 microm) than SAL (570.1+/-93.5 microm) and SPF (551.9+/-99.7 microm) rats as a result of a higher (P<0.05) hypertrophic zone (661.0+/-89.7 versus 362.8+/-71.6 and 353.0+/-93.9 microm, respectively). The increased size of the growth plate was associated with a greater number of chondrocytes and modifications in their structure, particularly in the hypertrophic zone adjacent to bone. In this zone, chondrocytes of NX animals were significantly (P<0.05) smaller (12080.4+/-1158.3 microm3) and shorter (34.1+/-2.5 microm) than those of SAL (16302.8+/-1483.4 microm3 and 37.8+/-2.0 microm) and SPF (14465.8+/-1521.0 microm3 and 36.3+/-1.8 microm). The interface between the growth plate cartilage and the metaphyseal bone appeared markedly irregular in NX rats. Kinetics of chondrocytes was also modified (P<0.05) in the NX rats, which had lower cell turnover per column per day (5.4+/-0.9), longer duration of hypertrophic phase (89.0+/-15.2 h), and reduced cellular advance velocity (7.4+/-2.2 microm/h) compared with SAL (8.0+/-1.6, 32.1+/-6.7 h, and 11.3+/-2.7 microm/h) and SPF (7.2+/-1.1, 34.8+/-5.1 h, and 10.1+/-2.5 microm/h). Cell proliferation was no different among the three groups. Because the growth plates of SPF and SAL rats were substantially not different, modifications observed in the NX rats cannot be attributed to the nutritional deficit associated with renal failure. These findings indicate that chronic renal failure depresses both the activity of the growth plate cartilage by altering chondrocyte hypertrophy and the replacement of cartilage by bone at the metaphyseal end. The two processes are differentially depressed since cartilage resorption is more severely lowered than cartilage enlargement and this leads to an accumulation of cartilage at the hypertrophic zone.

Animals↗
PubMed2003

Combined vertical and horizontal cable fixation of an extended trochanteric osteotomy site.

BACKGROUND: The use of an extended trochanteric osteotomy facilitates exposure and aids in the removal of a well-fixed femoral implant and cement during revision total hip arthroplasty. Occasionally, nonunion, fracture, and trochanteric migration have been reported following osteotomy. We evaluated the rate of healing of the osteotomy site and of implant stability when fixation was accomplished with use of vertical trochanteric and horizontal metaphyseal cable fixation (combined cable fixation). METHODS: The clinical and radiographic results of revision total hip arthroplasty with use of an extended trochanteric osteotomy followed by implantation of a distally porous-coated component and combined cable fixation of the osteotomy site in forty-two consecutive patients (forty-three hips) were reviewed. Intraoperative fracture at the osteotomy site occurred in five hips (12%). RESULTS: All osteotomy sites healed by six months, with an average time to union of fifteen weeks. One implant subsided 5 mm in a patient in whom a fracture had occurred at the time of the osteotomy. No trochanteric migration occurred. Two patients required a reoperation: one because of instability, and another because of recurrent infection. CONCLUSIONS: The extended trochanteric osteotomy facilitates revision of a well-fixed femoral component. Despite occasional intraoperative fracture at the osteotomy site, combined vertical trochanteric and horizontal metaphyseal cable fixation resulted in an excellent rate of healing and implant stability.

Adult↗
PubMed2005

Solitary epiphyseal enchondromas.

BACKGROUND: Enchondromas originating in the epiphyses of long bones are rare. The purpose of the present study was to evaluate the prevalence as well as the radiographic and clinical characteristics of epiphyseal enchondromas among patients who had been referred to the Armed Forces Institute of Pathology and Walter Reed Army Medical Center. METHODS: We performed a retrospective review of 761 patients who had been referred to our two institutions over an approximately fifty-five-year period and who received a final diagnosis of enchondroma. All lesions had been biopsied, and the pathological diagnosis had been confirmed. Lesions of the hands, feet, or axial skeleton (253 patients) as well as lesions that appeared to originate in the metaphysis or diaphysis (475 patients) were excluded. Only enchondromas of the long bones that originated in the epiphysis were analyzed. The study group included thirty-three patients (twenty male patients and thirteen female patients) with a mean age of 26.7 years, including eleven patients with open physes. We performed additional descriptive analyses with regard to patient age, gender, lesion location, clinical presentation, and treatment as well as an extensive radiographic analysis. RESULTS: The most common locations were the proximal part of the humerus (ten lesions; 30%) and the distal part of the femur (six lesions; 18%). The most common presenting symptom was pain (twenty-three patients). Radiographic analysis demonstrated extensive matrix mineralization in association with twenty-three lesions. Twenty-eight of the thirty-three lesions were geographically well defined; of these, twenty-one had sclerotic borders, and seven did not. Although all lesions were centered and were predominantly located within the epiphysis, twenty of the thirty-three lesions demonstrated radiographic evidence of metaphyseal extension, including four of the eleven lesions in patients with open physes. Twenty-four lesions extended into the subchondral bone. The mean size of the thirty-three enchondromas in greatest radiographic dimension was 2.7 cm (range, 1.1 to 4.9 cm). Twenty-six of the thirty-three lesions were amenable to surgical treatment with curettage with or without bone-grafting, with only one recurrence. With the limited follow-up available, no lesion underwent sarcomatous degeneration. CONCLUSIONS: Epiphyseal enchondromas are rare lesions. Although their biologic behavior appears to mirror that of conventional metaphyseal enchondromas, their proximity to the joint space may lead to more frequent painful symptoms, a propensity for physeal involvement, and the need for earlier definitive surgical intervention.

Adolescent↗
PubMed1991

Deferoxamine-induced bone dysplasia in patients with thalassemia major.

Metaphyseal irregularity and abnormal vertebral bodies resembling a bone dysplasia were seen in two of five children with thalassemia major who were begun on a regimen of hypertransfusion and chelation with deferoxamine before the age of 3 years. Similar changes were not seen in 22 other children in whom chelation was started after the age of 3. Whether the dysplastic bone growth was related to drug dose or age of onset of chelation could not be determined, as deferoxamine dosages differed in the two groups. Findings on radiographs included flattening of the thoracic and lumbar vertebral bodies, circumferential metaphyseal osseous defects, sharp zones of provisional calcification, and widened growth plates. Healing was noted in one of the patients after the dose of deferoxamine was decreased. Zinc levels in both affected patients did not differ from those in the 25 other chelated patients.

Adolescent↗
PubMed1993

Skeletal growth lines seen on radiographs of newborn infants: prevalence and possible association with obstetric abnormalities.

OBJECTIVE: Skeletal transverse metaphyseal and vertebral lines, seen frequently on radiographs of infants and children, are usually believed to result from interrupted bone growth. Such lines have not been systematically studied in neonates. Accordingly, I determined the prevalence of growth lines on chest radiographs of newborn infants and assayed the gestational and obstetric abnormalities that occurred with these infants. MATERIALS AND METHODS: Chest radiographs were obtained (over a 4-year period) in 3687 neonates within the first 48 hr after birth for clinical indications. A single observer prospectively examined the radiographs for the presence of skeletal lines. When skeletal lines were seen on chest radiographs, lines in the pelvis were also sought when this region was imaged during the first 48 hr after birth. The medical records of affected neonates were reviewed to determine the presence and nature of potential in utero injuries. RESULTS: Skeletal lines were noted on chest radiographs of 200 neonates (5%) and appeared most commonly as "bone-within-bone" vertebral bodies and as transverse metaphyseal lines in the proximal humeri. Of affected neonates, 176 (88%) were born prematurely (< 38 weeks' gestation) and 59 (30%) had significant intrauterine growth retardation. Obstetric risk factors, which were varied and often multiple, were noted in 177 neonates (89%). The most common of these factors were pregnancy-induced hypertension (58 patients), multiple gestations (48 patients), drug abuse (30 patients), magnesium therapy (30 patients), prescribed maternal medications (27 patients), preterm labor before final labor (23 patients), and oligohydramnios (20 patients). In 23 neonates, no gestational complications were identified. CONCLUSION: Skeletal lines in the population of neonates who require chest radiography are relatively common, and often but not invariably appear to occur in the setting of potentially significant prenatal injury. It is speculated that these lines represent a tool for identifying and exploring causes of intrauterine growth disturbance.

Bone and Bones↗
PubMed1994

Endemic fluorosis of the skeleton: radiographic features in 127 patients.

OBJECTIVE: A wide range of radiographic appearances have been reported in skeletal fluorosis, but little has been written about the spectrum of radiographic features. We evaluated the spectrum of radiographic appearances in this disorder to help with its diagnosis and differentiation from other metabolic skeletal disorders. MATERIALS AND METHODS: One hundred twenty-seven patients with clinically proved endemic fluorosis had radiographs of the chest, spine, pelvis, elbow, forearm, and knee obtained. The radiographic findings were classified as osteosclerosis, osteopenia, intermittent growth lines, diaphyseal widening, or soft-tissue ossification. Two different osteopenic patterns were defined: an osteoporotic pattern with overall decreased bone density and an osteomalacic pattern that combines the features of osteoporosis with bone deformity. Soft-tissue ossification included involvement of ligaments, tendons, and interosseous membranes. RESULTS: Ninety-eight of the patients (89% of the adults) had some evidence of calcification and/or ossification of the attachments of ligaments, tendons, muscles, and interosseous membranes. Osteosclerosis was seen in 54 patients (43%), and osteopenia was seen in 51 patients (40%). Of the patients with osteopenia, the osteoporotic pattern was seen in 28 and the osteomalacic pattern in 23. Growth lines were found in 89 patients (70%). Metaphyseal osteomalacic zones were found in children. Diaphyseal widening was present in 35 patients (28%). CONCLUSION: Endemic skeletal fluorosis can have a wide variety of radiographic appearances, including calcification and/or ossification of the attachments of soft-tissue structures to bone, osteosclerosis, osteopenia, growth lines, and metaphyseal osteomalacic zones.

Adolescent↗
PubMed1995

Inflicted skeletal injury: a postmortem radiologic-histopathologic study in 31 infants.

OBJECTIVE: The objective of this postmortem study was to use high-detail skeletal surveys, specimen radiography, and histopathologic analysis to determine the number, distribution, and age of inflicted skeletal injuries in infants studied at the University of Massachusetts Medical Center from 1984 to 1994. MATERIALS AND METHODS: Thirty-one infants (average age, 3 months) who died with inflicted skeletal injuries were studied with high-detail skeletal surveys and specimen radiography and histopathologic analysis. The distribution and number of fractures was determined for each technique, and dating was performed on the basis of radiologic and histologic criteria. The skull fractures noted in 13 cases were excluded from the numerical analysis. RESULTS: The radiologic-histopathologic correlation revealed 165 fractures involving the ribs in 84 (51%), long bones in 72 (44%), bones of the hands and feet in 6 (4%), clavicles in 2 (1%), and spine in 1 (< 1%). Of the 72 long bone fractures, the metaphyses were involved in 64 (89%, or 39% of the total), and the shaft was involved in 8 (11%, or 5% of the total). One hundred sixteen fractures were healing, 36 were acute, and 13 were of indeterminate age. In all but two infants, at least one healing fracture was present. Of fractures diagnosed histopathologically, specimen radiography increased the yield of fractures noted on skeletal survey from 58% to 92%. CONCLUSION: Most infants who die with inflicted injury have fractures at multiple sites. Metaphyseal and rib fractures are much more common than long bone shaft injuries, the opposite of the pattern found in older children. Because most abused infants who die have evidence of healing fractures at the time of autopsy, aggressive radiologic efforts to identify these injuries in living as well as in decreased infants appear justified.

Autopsy↗
PubMed2002

Patterns of premature physeal arrest: MR imaging of 111 children.

OBJECTIVE: The purpose of this study was to use MR imaging, especially fat-suppressed three-dimensional (3D) spoiled gradient-recalled echo sequences, to identify patterns of growth arrest after physeal insult in children. MATERIALS AND METHODS: We evaluated 111 children with physeal bone bridges (median age, 11.4 years) using MR imaging to analyze bridge size, location in physis, signal intensity, growth recovery lines, avascular necrosis, and metaphyseal cartilage tongues. Fifty-eight patients underwent fat-suppressed 3D spoiled gradient-recalled echo imaging with physeal mapping. The cause, bone involved, radiographic appearance, and surgical interventions (60/111) were also correlated. Data were analyzed with the two-tailed Fisher's exact test. RESULTS: Posttraumatic bridges, accounting for 70% (78/111) of patients, were most often distal, especially of the tibia (n = 43) and femur (n = 14), whereas those due to the other miscellaneous causes were more frequently proximal (p < 0.0001). The position of the bridge in the physis was related to the bone involved (p < 0.0001). Sixty-five percent of distal tibial bridges involved the anteromedial physis, whereas 60% of the distal femoral arrests were central. Larger bridges had higher T1 signal intensity (p < 0.008). Oblique growth recovery lines were seen exclusively with bridges involving the peripheral physis (p = 0.002) and smaller, more potentially resectable bridges. Metaphyseal cartilaginous tongues were seen with all causes, but avascular necrosis was exclusively posttraumatic (p = 0.03). Signal characteristics and bridge size did not vary with the cause. CONCLUSION: Premature physeal bony bridging in children is most often posttraumatic and disproportionately involves the distal tibia and femur where bridges tend to develop at the sites of earliest physiologic closure, namely anteromedially and centrally, respectively. MR imaging, especially with the use of fat-suppressed 3D spoiled gradient-recalled echo imaging, exquisitely shows the growth disturbance and associated abnormalities that may follow physeal injury and guides surgical management.

Adolescent↗
PubMed2004

Age-related vascular changes in the epiphysis, physis, and metaphysis: normal findings on gadolinium-enhanced MRI of piglets.

OBJECTIVE: We sought to study the normal enhancement patterns seen on MRIs of the epiphysis, physis, and metaphysis and age-related vascular changes in piglets using gadoteridol, a nonionic gadolinium chelate. MATERIALS AND METHODS: We quantitatively and qualitatively analyzed the normal changes on sequential T1-weighted images after the IV administration of gadoteridol. In an investigation approved by the research animal care committee at our hospital, we studied the proximal and distal femurs of 26 piglets 1-6 weeks old and correlated the enhanced images with findings on intermediate-weighted, T2-weighted, and gradient-recalled echo images and at histologic examination. RESULTS: We observed early enhancement of the epiphyseal vascular canals, the main physis, the physis of the secondary ossification center, and a metaphyseal band adjacent to the physis. Enhancement of the epiphyseal and metaphyseal marrow and of the epiphyseal cartilage was slower. In the epiphyseal cartilage, we saw three phases of enhancement: vascular, canalicular, and cartilaginous. As the piglets matured, enhancement of the epiphyseal cartilage decreased, and the epiphyseal vascular canals were less conspicuous. Physeal enhancement was greatest during the first week of life, declined at 3 weeks, and subsequently increased again as the physis came to lie adjacent to a larger segment of the epiphyseal ossification center. CONCLUSION: Gadoteridol-enhanced MRIs showed multiple cartilaginous and vascular structures of the growing skeleton. With maturity and progressive epiphyseal ossification, epiphyseal cartilage enhancement decreased, and physeal cartilage enhancement increased.

Aging↗
PubMed2003

Effect of bone diameter and eccentric loading on fatigue life of cortical screws used with interlocking nails.

OBJECTIVE: To test the effects of bone diameter and eccentric loading on fatigue life of 2.7-mm-diameter cortical bone screws used for locking a 6-mm-diameter interlocking nail. SAMPLE POPULATION: Eighteen 2.7-mm-diameter cortical bone screws. PROCEDURE: A simulated bone model with aluminum tubing and a 6-mm-diameter interlocking nail was used to load screws in cyclic 3-point bending. Group 1 included 6 screws that were centrally loaded within 19-mm-diameter aluminum tubing. Group 2 included 6 screws that were centrally loaded within 31.8-mm-diameter aluminum tubing. Group 3 included 6 screws that were eccentrically loaded (5.5 mm from center) within 31.8-mm-diameter aluminum tubing. The number of cycles until screw failure and the mode of failure were recorded. RESULTS: An increase in the diameter of the aluminum tubing from 19 to 31.8 mm resulted in a significant decrease in the number of cycles to failure (mean +/- SD, 761,215 +/- 239,853 to 16,941 +/- 2,829 cycles, respectively). Within 31.8-mm tubing, the number of cycles of failure of eccentrically loaded screws (43,068 +/- 14,073 cycles) was significantly greater than that of centrally loaded screws (16,941 +/- 2,829 cycles). CONCLUSIONS AND CLINICAL RELEVANCE: Within a bone, locking screws are subjected to different loading conditions depending on location (diaphyseal vs metaphyseal). The fatigue life of a locking screw centrally loaded in the metaphyseal region of bone may be shorter than in the diaphysis. Eccentric loading of the locking screw in the metaphysis may help to improve its fatigue life.

Animals↗
PubMed2006

Effect of one- and two-pin reference anchoring systems on marker stability during total knee arthroplasty computer navigation.

OBJECTIVE: This study investigated different infrared marker reference base attachments in cadaveric bone and their effects on alignment outcome when different loads were applied. MATERIAL AND METHODS: Five cadaveric specimens were used to test four reference base attachments: a locking one-pin (4.0 mm and 5.0 mm pins) and a two-pin clamp (Hoffman fixator, 3.0 mm and 5.0 mm pins, Stryker Inc., NJ). Each was tested with metaphyseal and diaphyseal attachments. A navigation system (Stryker Navigation, MI) was used for testing with applied incremental loads and torques (65 N and 1.0 Nm) to the different reference base configurations. RESULTS: With 65 N the maximum change in distance to a verification point was 4.3 + 1.6 mm with the 4.0 mm locking pin in metaphyseal bone. No difference in verification point distances was found with any two-pin configuration. Alignment changes greater than 4 degrees resulted with the 65 N loads and a 4.0 mm pin. CONCLUSION: The results may prove beneficial in comparing the resulting error of different manufacturers and allow surgeons to realize the variability that may occur through incidental contact in the operating room.

Arthroplasty, Replacement, Knee↗