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Epiphyseal tubercle and peripheral cupping can influence the development of slipped capital femoral epiphysis (SCFE) and Cam morphology. During normal skeletal growth, epiphyseal tubercle shrinks while the peripheral cupping grows. We hypothesized that epiphyseal tubercle act as the primary stabilizer of the head-neck junction at early stages and this role is gradually transferred to epiphyseal cupping as the tubercle shrinks and cupping grows. From a cohort of 80 boys and girls (8-15 years old) with normal hips, CT scans of 5 subjects corresponding to minimum, 25th percentile, median, 75th percentile and maximum relative tubercle and cupping height were used to develop 3D finite element models. In vivo measured hip loads were used to study load sharing between the tubercle and peripheral cupping under combined and uniaxial loads exerted on femoral head during a range of daily activities. Lower epiphyseal tubercle height, larger epiphyseal cupping height and bigger differences in tubercle and cupping heights were strongly associated with increased epiphyseal cupping to epiphyseal tubercle stress ratios (R 2  > 0.7). We found lower peripheral cupping stresses relative to the tubercle (cupping to tubercle stress ratio <1) in hips with larger tubercle and smaller cupping. The relative decreases in tubercle size along with increased in peripheral cupping in our models gradually shifted the load distribution to higher stresses in the periphery compared to the epiphyseal tubercle area (cupping to tubercle stress ratio >1). Both tubercle and cupping play a substantial role in sharing the generated stresses across the head-neck junction under all tested loading conditions. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1571-1579, 2019., (© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Unlabelled: Micro-finite element analysis applied to high-resolution (0.234-mm length scale) MRI reveals greater whole and cancellous bone stiffness, but not greater cortical bone stiffness, in the distal femur of female dancers compared to controls. Greater whole bone stiffness appears to be mediated by cancellous, rather than cortical bone adaptation., Introduction: The purpose of this study was to compare bone mechanical competence (stiffness) in the distal femur of female dancers compared to healthy, relatively inactive female controls., Methods: This study had institutional review board approval. We recruited nine female modern dancers (25.7±5.8 years, 1.63±0.06 m, 57.1±4.6 kg) and ten relatively inactive, healthy female controls matched for age, height, and weight (32.1±4.8 years, 1.6±0.04 m, 55.8±5.9 kg). We scanned the distal femur using a 7-T MRI scanner and a three-dimensional fast low-angle shot sequence (TR/TE=31 ms/5.1 ms, 0.234 mm×0.234 mm×1 mm, 80 slices). We applied micro-finite element analysis to 10-mm-thick volumes of interest at the distal femoral diaphysis, metaphysis, and epiphysis to compute stiffness and cross-sectional area of whole, cortical, and cancellous bone, as well as cortical thickness. We applied two-tailed t-tests and ANCOVA to compare groups., Results: Dancers demonstrated greater whole and cancellous bone stiffness and cross-sectional area at all locations (p<0.05). Cortical bone stiffness, cross-sectional area, and thickness did not differ between groups (>0.08). At all locations, the percent of intact whole bone stiffness for cortical bone alone was lower in dancers (p<0.05). Adjustment for cancellous bone cross-sectional area eliminated significant differences in whole bone stiffness between groups (p>0.07), but adjustment for cortical bone cross-sectional area did not (p<0.03)., Conclusions: Modern dancers have greater whole and cancellous bone stiffness in the distal femur compared to controls. Elevated whole bone stiffness in dancers may be mediated via cancellous, rather than cortical bone adaptation.

In order to identify pertinent models of cortical and cancellous bone regeneration, we compared the kinetics and patterns of bone healing in mouse femur using two defect protocols. The first protocol consisted of a 0.9-mm-diameter through-and-through cortical hole drilled in the mid-diaphysis. The second protocol was a 0.9-mm-diameter, 1-mm-deep perforation in the distal epimetaphyseal region, which destroyed part of the growth plate and cancellous bone. Bone healing was analyzed by ex vivo micro-computerized X-ray tomography and histology. In the diaphysis, the cortical gap was bridged with woven bone within 2 weeks. This newly formed bone was rapidly remodeled into compact cortical bone, which showed characteristic parameters of intact cortex 4 weeks after surgery. In the epimetaphysis, bone formation was initiated at the deepest region of the defect and spread slowly toward the cortical gap. In this position, newly formed bone quickly adopted the characteristics of trabecular bone, whereas a thin compact wall was formed at its external border, which reached the density of intact cortical bone but failed to bridge the cortical gap even 13 weeks after surgery. This comparative study indicates that the diaphyseal defect is a model of cortical bone healing and that the epimetaphyseal defect is a model of cancellous bone repair. These models enable experimental genetics studies to investigate the cellular and molecular mechanisms of spontaneous cortical and cancellous bone repair and may be useful for pharmacological studies.

In his model of the biomechanics of the proximal human femur, Friedrich Pauwels assumes a resultant force acting on the femoral head that is created by the partial body weight and the force of the abductor muscles inserting at the greater trochanter. This model suggests a tensile force in the region of the greater trochanter. An exact examination of the muscle insertions at the greater trochanter resulted in a contrasting hypothesis assuming a local compression stress in the region of the greater trochanter. The aim of this study was to examine which hypothesis is favored by the internal architecture of the proximal femur. Based on the architectural software Allplan(R), we performed an extended analysis of the trabecular structure within the proximal femur using CT scans of 10 human cadaver femora altogether. According to our results, both the medial and the trochanteric trabecular systems are orientated approximately perpendicular to the arcuate trabecular system [angles between systems ranging from 84.6 to 93.0 degrees (mean angle 90.7 degrees ) and from 80.9 to 86.5 degrees , (mean angle 84.9 degrees ), respectively]; furthermore, the medial trabecular system is orientated perpendicular to the epiphysis of the femoral head (mean of angles: 94.7 degrees ). The biomechanical interpretation of these results strongly supports the idea of compressive stress in the region of the greater trochanter and makes a predominant tensile force of the abductor muscles highly unlikely., (2009 S. Karger AG, Basel.)

Mechanical loading is well known to stimulate bone remodeling. Load-driven interstitial fluid flow and molecular transport have been postulated to play a role in the enhancement of bone formation. In order to evaluate load-driven molecular transport in a lacunocanalicular network, we conducted fluorescence recovery after photobleaching (FRAP) experiments using lacunae stained with uranine (376 Da). Loads were applied to a mouse femur ex vivo with a novel knee-loading modality, where the distal epiphysis was loaded with a sinusoidal force at 2 Hz. The lacunae in the diaphysis located 25% (approximately 4 mm) proximal to the loading site were photobleached and sequentially imaged, and a time constant for fluorescence recovery was determined both with and without knee loading. The time constant was estimated as the period to recover 63% of fluorescent intensity using a best-fit exponential curve. The results reveal that the applied loads shortened the time constant from 33 +/- 9 s with non-loading control to 25 +/- 11 s with knee loading (p = 0.0014). The strain in the measurement site was <100 microstain along the femoral midshaft, which was an order of magnitude smaller than the minimum effective strain threshold for bone remodeling. Taken together, the current study supports the notion that molecular transport in cortical bone is enhanced by the loads applied to the epiphysis without inducing significant in situ strain in the diaphysis.

Objective: The incidence of bovine spongiform encephalopathy has resulted in marine collagen hydrolysate (low-molecular-weight gelatin) being sold as supplements and cosmetics in Japan. Shark skin collagen is one of the important sources of marine collagen. We examined the effect of shark skin gelatin in an osteoporosis model animal., Methods: Shark skin gelatin was orally administered to ovariectomized rats with a low-protein diet. Bone mineral density of the right femur was measured. Collagen and glycosaminoglycan in the tibial end were extracted and analyzed by western blotting and cellulose acetate membrane electrophoresis, respectively., Results: Administering collagen to the ovariectomized rats resulted in the bone mineral density of the femur epiphysis being higher than that in the sham-operated rats. The contents of type I collagen and glycosaminoglycan in the epiphysis were increased by administering shark skin gelatin., Conclusions: These results indicated that shark skin gelatin would be useful as a dietary supplement for treating osteoporosis.

Purpose: This study was conducted to verify the predictive value of epiphyseal ossification center measurements in estimating gestational age., Methods: Women with singleton pregnancies of 30-40 weeks gestation (n = 377) were enrolled in this prospective study. The distal femoral, proximal tibial, and proximal humeral ossification centers were identified and measured. A nomogram of fetal bone development was created using the sum of the three diameters., Results: Gestational age correlated well with the diameters of the distal femoral and the proximal tibial epiphyseal ossification centers but even better with the sum of the three ossification centers. Positive predictive values of the fetus having gestational age of at least 37 weeks when the sum of the three centers was 7, 11, and 13 mm were 82%, 94%, and 100%, respectively. A nomogram was created using the sum of the ossification centers for 30-40 weeks' gestational age., Conclusions: Ultrasonographic visualization of the epiphyses ossification centers may be a useful marker of fetal gestational age., (Copyright 2005 Wiley Periodicals, Inc.)

A technique is submitted together with a device for measuring the thigh-bone proximal and distal metaepiphyses substantia spongiosa macrohardness to assess stability of the diaphyseal fractures intramedullary osteosynthesis. Data are secured on sizes of the medullary cavity cross-section, thickness of the compact bone tissue, indices for macrohardness of the femoral metaepiphyses substantia spongiosa in frontal and sagittal planes. The results obtained will, we believe, help in finding an optimum construction and technique for osteosynthesis.

Hemodynamic changes at the distal femoral epiphysis measured by recording intraosseous pressure (IOP) were investigated in mature and juvenile dogs after changes in knee-joint position and intracapsular infusion of 3 ml isotonic saline solution. Juvenile and mature animals responded to infusion test with a similar 5-fold increase in intracapsular pressure. A 2-fold increase in IOP was found when knee-joint flexion passed from 30 degrees to complete flexion. In juvenile dogs, IOP values were lower than in adults both in complete knee flexion and during infusion test. The similar response to joint hyperpressure tests observed in adult and juvenile dogs suggests that the barrier effect of the growth plate for epiphyseal venous drainage has no major influence in the hemodynamics of the distal femoral epiphysis.

The present investigator implanted sintered porous hydroxyapatite rod (phi 3 mm x 10 mm) in the distal metaphysis or epiphysis of the right femur of 40 Japanese white rabbits and studied tissue reaction around hydroxyapatite (abbreviated as HAp) with radiograms and microphotographs. As control, stainless-molybdenum alloyed (abbreviated as SMO) rod was used. In the groups with metaphyseal implantation of HAp or SMO, the distance between the center of implant and the distal femoral epiphyseal line increased during 12 weeks after operation. New bone was directly bonded to implanted material only after implantation of HAp. Ratio of length of HAp bone interface and length of HAp circumference was greater in the groups with implantation in the metaphysis 2 weeks after operation than those in the epiphysis. On the other hand, it was greater in groups with implantation in the epiphysis than those in the metaphysis 12 weeks after operation. In the groups with metaphyseal implantation of HAp, the ratio in groups 2 weeks after operation was greater than that in 12 weeks and there was a firm interrelationship between the ratio and the distance between the center of implant and the distal femoral epiphyseal line.

Experimental physial distraction was carried out in the distal part of the femur in 45 two-month old lambs in order to study the basic mechanisms of lengthening as well as the viability of the growth cartilage after using this method. The animals were divided into three groups (A, B and C), and each group into three subgroups (1, 2 and 3) according to the rate of distraction used (2 mm/day, 1 mm/day, 0.5 mm/day) and the time of sacrifice. The results obtained show that the basic lengthening mechanisms consists, firstly, in the production of a fracture between the metaphysis and the epiphysis and, secondly, that the lower the distraction speed employed, the greater is the short-term and long-term viability of the growth cartilage. Optimum viability was observed at a distraction rate of 0.5 mm/day. On this basis we conclude that in clinical practice physical distraction could be indicated for children at an early stage of skeletal growth and repeated later provided that the rate of distraction is kept within reasonable limits.

A modular apparatus to measure the bending and torsional properties of the rat femur is presented. Both intact femur diaphyses and diaphyseal fractures in different phases of healing can be tested. It is also possible to measure the bending-strength of the distal femur metaphysis and the epiphyseal plate. The apparatus can be used to investigate the effect of drugs and hormones on the remodelling of the rat femur.

The in vitro breaking forces of the distal femoral growth plates of young rabbits were measured as a background to the design of a bone lengthening method, using epiphyseal distraction. The mean breaking force in 16 femora was 12.98 +/- 3.48 kg and the mean strain was 0.91 +/- 0.33 mm. The mean stress in 10 femora was 14.51 +/- 3.88 kg/cm2. The procedure was repeated, after applying a 1.0 kg dead weight to 6 femora for 24 hours and the breaking force was then 15.01 +/- 4.70 kg, with a mean strain of 0.85 +/- 0.62 mm. A further 8 rabbits then underwent epiphyseal distraction for 2 days in vivo, with 1 or 2 kg forces delivered to two parallel K wires by a pair of spring devices, whereupon the femora were removed and tested as before. The breaking force on the distracted side was now only 8.91 +/- 3.71 kg, compared with 13.99 +/- 3.40 kg on the control side. Although not fractured, these plates had obviously been weakened. The clinical implication of this is discussed.

A prospective sonographic evaluation of the distal femoral and proximal tibial epiphyseal ossification centers in 228 normal pregnant women was carried out from 28 to 40 weeks' gestation. The mean gestational age at which the distal femoral epiphysis and proximal tibial epiphysis were imaged was 34 and 38 weeks, respectively. The distal femoral epiphysis was not identifiable before 28 weeks but was observed in 72% of fetuses at 33 weeks and in 94% of fetuses at 34 weeks' gestation. The presence of a distal femoral epiphysis measuring 1 or 2 mm was associated with a gestational age of greater than 33 weeks in 87.0% of fetuses, whereas a distal femoral epiphysis measuring greater than or equal to 3 mm was associated with a gestational age greater than 37 weeks in 85% of fetuses. The proximal tibial epiphysis, which was absent before 34 weeks' gestation, was observed in 56% of fetuses at 36 weeks, in 80% of fetuses at 37 weeks, and in 100% of fetuses at 39 weeks of gestation. The presence of a proximal tibial epiphysis of 1 or 2 mm was associated with a gestational age of greater than 36 weeks in 88% of fetuses, whereas a proximal tibial epiphysis greater than or equal to 3 mm was associated with a gestational age of greater than 38 weeks in 94% of fetuses. The sonographic evaluation of distal femoral epiphysis/proximal tibial epiphysis can be used as independent markers for estimation of gestational age during the third trimester, a period in which standard fetal biometric estimates of gestational age are least accurate.

After the determination of the shear strength and modes of failure of the capital femoral epiphyseal plates in twenty-five pairs of hips obtained post mortem from children five days to fifteen years and ten months old, with the plate intact on one side and with the perichondrial fibrocartilaginous complex removed on the other, the gross and microscopic morphology was studied. The shear strength of the human epiphyseal plate varied with age and was greatly dependent on the surrounding perichondrial complex in infancy and early childhood, but less so in adolescence. When this complex was excised, the strength of the epiphyseal plate was diminished, especially in specimens from younger children. The forces necessary to cause slipping were found to be within the physiological range of the force that would be generated in overweight children, suggesting that purely mechanical factors may play a major role in the etiology of slipped capital femoral epiphysis.