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PubMed1996

Local bone turnover in the metaphysis of the proximal tibia and the lumbar vertebra during the early periods after ovariectomy in rats.

To clarify the local changes in bone formation and resorption during the early period after ovariectomy (OVX), 200 SD rats, 4 months of age, underwent OVX or sham surgeries and seven to nine rats from each group were terminated at 1, 3, 7, 11, 15, 19, 23, 28, 35, 63, and 91 days postsurgery after tetracycline labeling. Serum intact osteocalcin levels were measured. Undecalcified sections of the 5th lumbar body (L5) and the right proximal tibia were measured for trabecular bone area, the labeled perimeters and the interlabeling distances after Villanueva's staining. On the 4th lumbar body (L4) and the left proximal tibia, undecalcified sections were measured for the trabecular osteoclast by tartrate-resistant acid phosphatase staining. The uterine horns were atrophied on the 3rd postovariectomy day (day 3). Serum osteocalcin levels increased on day 7 and reached the highest value on day 23. In either L5 or the metaphysis of the proximal tibia, trabecular bone volume (BV/TV) significantly decreased on day 15. The trabecular bone loss on day 28 was approximately 50% in the tibia and 15% in the L5. In either the lumbar or the tibia, osteoclast numbers significantly increased at day 3, and peaked between days 15 and 23. In the tibia, however, the bone formation rates (BFR/BS) were significantly reduced on the 3rd and 7th post-surgical days compared with the start value for both the OVX and sham groups. The BFR/BS values in L5 did not decrease during the first 7 days in either group. The BFR/BS values were then increased for both L5 and the tibia after day 7. These data clearly demonstrated that the local bone turnover 7 days post-OVX was identical in the proximal tibia and the lumbar vertebra. In the proximal tibia, however, it may be suggested that the increased bone resorption and reduced formation within 7 days after OVX due to the combined effects of both an estrogen deficiency and the surgical intervention would possibly play a critical role in the greater magnitude of the trabecular bone loss.

Animals↗
PubMed2002

The effect of low intensity pulsed ultrasound applied to rabbit tibiae during the consolidation phase of distraction osteogenesis.

The purpose of this study was to determine if low intensity pulsed ultrasound (LIPU) accelerated the maturation of regenerate bone when applied after distraction in a rabbit model. A mid-tibial osteotomy was performed in 26 New Zealand white rabbits and an external fixator applied anteromedially. After a seven day latency period, the tibiae were distracted 0.5 mm every 12 h for 10 days. Thirteen of the rabbits received LIPU for 20 min/day (treatment group) and 13 received sham LIPU (control group) from day 17 until sacrifice on day 37. Radiographs were taken weekly after distraction and the total and mineralized areas of the callus were measured. After sacrifice, dual-energy X-ray absorptiometry, torsional testing to failure, and histomorphometry were performed. Ultrasound-treated tibiae were a mean of 68.8 +/- 3.8% as stiff as and 68.2 +/- 6.0% as strong as the contralateral tibiae. Control tibiae were 78.7 +/- 7.0%, as stiff as and 70.2 +/- 7.9% as strong as the contralateral tibiae. The differences in stiffness and strength were not significant (p = 0.39 and 0.81, respectively) with the number of the animals tested in the study. The treatment group was 91.6% as dense as the contralateral side and the control group was 88.5% as dense as the contralateral side (p = 0.84). Radiographs revealed a significantly larger callus in the LIPU-treated tibiae at 1, 2 and 3 weeks after distraction compared to control tibiae (p < 0.01, 0.008 and 0.05, respectively). Histomorphometry revealed significantly less fibrous tissue in the LIPU-treated tibiae (p < 0.05) and a strong trend towards more bone in the LIPU-treated tibiae compared to controls (p = 0.06). LIPU was found to increase the size of the distraction callus and it might alter the composition of regenerate bone but it did not have a positive effect on the mechanical properties or density of regenerate bone when applied during the consolidation phase of distraction osteogenesis.

Animals↗
PubMed1995

The measure and mismeasure of the tibia: implications for stature estimation.

Trotter and Gleser's stature estimation formulae, based on skeletons of the Terry collection and on WWII casualties, have been widely used in forensic work. Our work with the Terry and WWII data yielded tibia lengths too short compared to other data sets. Using Trotter's original measurements, we discovered that she consistently mismeasured the tibia. Contrary to standard practice and her own definitions, she omitted the malleolus from the measurement. Trotter's measurements of the tibia are 10 to 12 mm shorter than they should have been, resulting in stature estimations averaging 2.5 to 3.0 cm too great when the formulae are used with properly measured tibia. We also examined tibia lengths of Korean War casualties, which were measured by technicians rather than by Trotter. Korean tibia measurements are also too short, but by a smaller amount than Terry and WWII. Since the Korean tibia are unavailable for restudy, it is unclear how they were measured. Estimation of stature from Trotter and Gleser's tibia formulae is to be avoided if possible. If necessary, the 1952 formulae could be used with tibia measured in the same manner that Trotter measured, excluding the malleolus.

Asian People↗
PubMed1997

Biomechanical properties of human tibias in long-term spinal cord injury.

Long-term spinal cord injury (SCI) profoundly alters skeletal structure and function. In this study, the biomechanical properties of tibias from persons with SCI and from individuals closely matched in age and size but without SCI were quantified at both the structural and material levels. Nondestructive torsion tests were performed to determine apparent shear moduli for the tibia. The cortical thicknesses and polar moment of inertia were determined numerically. Four-point bending tests were performed to determine flexural modulus of elasticity on cortical bone specimens of the tibia. The apparent shear moduli of the SCI tibias were found to be lower than the non-SCI tibias (p < 0.05). The cortical thicknesses of the SCI tibias were significantly thinner than the control tibias (p < 0.05), while the polar moment of inertia showed no significant differences between control and SCI tibial cross sections (p > 0.05). The flexural modulus of elasticity of the cortical bone specimens were lower in the SCI tibias than the controls (p < 0.05). These differences suggest that tibias may undergo micro-structural changes as well as structural adaptation following SCI, which alter their mechanical properties.

Aged↗
PubMed2002

Modified tibial nails for treating distal tibia fractures.

OBJECTIVE: To determine the biomechanical consequences of cutting one centimeter off the tip of a tibial nail when treating distal tibia fractures with intramedullary nails. DESIGN: Randomized laboratory investigation using matched pairs of cadaveric tibias with osteotomies made to resemble distal tibia fractures extending to four and five centimeters from the tibiotalar joints. INTERVENTION: The smaller (four-centimeter) distal tibias were stabilized using ten-millimeter diameter tibial nails that had been modified by removing the distal one centimeter of the nail. The five-centimeter distal tibias were stabilized with standard ten-millimeter diameter tibial nails. Each tibia was tested in elastic compression, rotation, and compression-bending on a servohydraulic materials testing machine. MAIN OUTCOME MEASUREMENTS: Stiffness was calculated for each type of loading to compare stability of the modified nail construct to that of the standard nail construct. RESULTS: Four-centimeter distal tibia fragments stabilized with modified nails have comparable stiffness in compression and in torsion to five-centimeter distal tibia fragments stabilized with standard tibial nails. The stiffness in compression-bending was surprisingly low in both groups and differed by only 3.7 percent. CONCLUSIONS: Removal of one centimeter from the tip of a tibial nail allows placement of two distal interlocking screws in tibial fractures located four centimeters from the tibiotalar joint. The fixation strength achieved is comparable to that of standard intramedullary nailing of tibial fractures located five centimeters from the tibiotalar joint using two distal interlocking screws. Fixation strength with these distal fractures, however, is not strong enough to resist moderate compression-bending loads. Thus, patients with distal tibia fractures treated with intramedullary nailing must follow weight-bearing restrictions until significant fracture healing occurs to prevent coronal plane malalignment of the fracture.

Biomechanical Phenomena↗
PubMed2003

The proximal tibia metaphysis: a reliable donor site for bone grafting?

Low complication rates have been reported when cancellous bone is taken from the proximal tibia. The current study was done to determine the volume of cancellous bone that can be harvested from the proximal tibia and to determine the risk for postoperative tibia plateau fracture. The average compressed volume that could be harvested from nine tibiae was 5.4 cc compared with a reported volume of 6.0 cc from the iliac crest. In eight cadavers, the proximal tibia was decancellated in eight tibias. The decancellated and the matching eight contralateral intact tibias were loaded to determine the force required to cause a tibial plateau fracture. The null hypothesis, that there is no difference between the decancellated and the intact tibias, could not be rejected. The current experimental study supports the clinical findings that a sufficient amount of cancellous bone can be harvested from the proximal tibial metaphysis and that the risk of postoperative fracture is not increased. Therefore, the proximal tibia is a reliable cancellous bone graft donor site for clinical practice.

Adult↗
PubMedDate not supplied

Pseudarthrosis of the rabbit tibia: a model for congenital pseudarthrosis?

The purpose of this study was to create a rabbit model of a pseudarthrosis of the tibia by passively constricting circumferential diaphyseal growth. A circumferential strip of Marlex mesh was placed around both tibiae of eight growing rabbits. It was sutured as a circumferential tube on the experimental tibia and not sutured together on the control side. The experimental tibiae developed significant narrowing, cystic changes, and sclerosis. Five of 11 experimental tibiae went on to pathological fracture, compared to no fractures in the eight control tibiae. The mesh was sutured together around both tibiae in another six rabbits. Release of the band 6 weeks later allowed healing of the narrowed tibiae, with or without an experimentally produced fracture. We conclude a passive constriction phenomenon may contribute to the development of congenital pseudarthrosis of the tibia. Removal of the band improved the chances of healing, which has implications for the treatment of children.

Animals↗
PubMed2004

Insertion torque pullout strength relationship of soft tissue tendon graft tibia tunnel fixation with a bioabsorbable interference screw.

PURPOSE: The purpose of this study was to evaluate the relationship between insertion torque and the biomechanical characteristics of soft tissue tendon graft tibia fixation with a bioabsorbable interference screw. TYPE OF STUDY: Biomechanical study. METHODS: Doubled tibialis anterior allografts (n = 20, length = 100 mm, diameter = 9 mm) prepared for anterior cruciate ligament (ACL) reconstructions were divided into 3 groups. Maximum insertion torque was measured as grafts were fixed by the same surgeon with a 10-mm diameter, 35-mm long screw in a 7-mm diameter tunnel (dilated to 9 mm) created in either 0.16 or 0.32 g/cm3 dense synthetic bone or cadaveric tibiae (0.84 +/- 0.15 g/cm2). Tensile testing to construct failure was then performed. RESULTS: All constructs failed by tunnel pullout. Higher density synthetic bone had greater load at failure than lower density synthetic bone (486.6 +/- 83.8 v 271.6 +/- 52.6 N, P <.0001) and a slightly greater proportion of variance could be explained in synthetic bone (R2 = 0.74, P <.0001) than in cadaveric tibiae (R2 = 0.64, P =.017). Higher density synthetic bone displayed greater stiffness than lower density synthetic bone (68.1 +/- 21.6 v 37.7 +/- 11.2 N/mm, P =.012) and a higher proportion of variance could be explained in cadaveric tibiae (R2 = 0.72, P =.008) than in synthetic bone (R2 = 0.48, P =.012). Greater insertion torque levels were seen in higher density synthetic bone (2.97 +/- 0.35 v 1.24 +/- 0.06 Nm, P <.0001) than in lower density synthetic bone, and a higher proportion of variance could be explained in synthetic bone (R2 = 0.94, P <.0001) than in cadaveric tibiae (R2 = 0.74, P =.006). CONCLUSIONS: Strong relationships were evident between insertion torque, bone mineral density (BMD) and load to failure across constructs. Differences between the synthetic bone groups and cadaveric tibiae, however, suggest the influence of mixed cortical and cancellous bone, nonuniform structural patterning, and differing BMD levels and distributions in the cadaveric tibiae. CLINICAL RELEVANCE: Soft tissue graft tibial tunnel fixation is directly related to insertion torque and BMD. Synthetic models with mixed bone characteristics are needed to more accurately depict human tibiae during fixation testing.

Absorbable Implants↗
PubMed1998

Osteogenic response of rabbit tibia to hydroxyapatite particle-Plaster of Paris mixture.

A mixture of hydroxyapatite (HA) particles and plaster of Paris (POP) with saline solution was injected into the bone marrow of 30 unilateral tibiae of 30 rabbits. As a control, POP with saline solution was similarly injected into the bone marrow of 30 unilateral tibiae of 30 additional rabbits. Five rabbits in each group were killed 2, 4, 8, 12, 24 and 40 weeks after injection. Histological examination was performed on three tibiae of five killed animals, and X-ray diffraction analysis of the bone marrow was performed on the remaining two tibiae. In two of three tibiae, bridges of new bone were formed between the hydroxyapatite particles and the cortical bone, 4 weeks after the injection of the HA particle-POP mixture. New bone formation was seen in all three tibiae at 8 weeks and thereafter. No new bone formation was observed in the tibiae of the control group. The affinity index, a parameter of osteogenesis, was 0% at 2 weeks, 52.2+/-14.0% at 4 weeks, 74.8+/-5.3% at 8 weeks, 86.1+/-6.1% at 12 weeks, 90.1+/-8.3% at 24 weeks and 92.8+/-4.1% at 40 weeks after injection. Statistically significant increases were found between the affinity indexes of 2 weeks and 4 weeks and between those of 4 weeks and 8 weeks, p < 0.03 and p < 0.05, respectively. Between 12, 24 and 40 weeks, the indexes showed tendencies toward increases. X-ray diffraction of bone marrow of two tibiae into which HA particle-POP mixture or POP alone was injected showed that POP had disappeared 8 weeks after injection.

Animals↗
PubMedDate not supplied

Low-power laser irradiation improves histomorphometrical parameters and bone matrix organization during tibia wound healing in rats.

The influence of daily energy doses of 0.03, 0.3 and 0.9 J of He-Ne laser irradiation on the repair of surgically produced tibia damage was investigated in Wistar rats. Laser treatment was initiated 24 h after the trauma and continued daily for 7 or 14 days in two groups of nine rats (n=3 per laser dose and period). Two control groups (n=9 each) with injured tibiae were used. The course of healing was monitored using morphometrical analysis of the trabecular area. The organization of collagen fibers in the bone matrix and the histology of the tissue were evaluated using Picrosirius-polarization method and Masson's trichrome. After 7 days, there was a significant increase in the area of neoformed trabeculae in tibiae irradiated with 0.3 and 0.9 J compared to the controls. At a daily dose of 0.9 J (15 min of irradiation per day) the 7-day group showed a significant increase in trabecular bone growth compared to the 14-day group. However, the laser irradiation at the daily dose of 0.3 J produced no significant decrease in the trabecular area of the 14-day group compared to the 7-day group, but there was significant increase in the trabecular area of the 15-day controls compared to the 8-day controls. Irradiation increased the number of hypertrophic osteoclasts compared to non-irradiated injured tibiae (controls) on days 8 and 15. The Picrosirius-polarization method revealed bands of parallel collagen fibers (parallel-fibered bone) at the repair site of 14-day-irradiated tibiae, regardless of the dose. This organization improved when compared to 7-day-irradiated tibiae and control tibiae. These results show that low-level laser therapy stimulated the growth of the trabecular area and the concomitant invasion of osteoclasts during the first week, and hastened the organization of matrix collagen (parallel alignment of the fibers) in a second phase not seen in control, non-irradiated tibiae at the same period. The active osteoclasts that invaded the regenerating site were probably responsible for the decrease in trabecular area by the fourteenth day of irradiation.

Animals↗
PubMed2003

Time course of epiphyseal growth plate fusion in rat tibiae.

Although the rat is the most common animal model used in studying osteoporosis, it is often used inappropriately. Osteoporosis is a disease that most commonly occurs in humans long after growth plate fusion with the associated cessation of longitudinal bone growth, but there has been a question as to when or to what extent the rat growth plate fuses. To investigate this question, we used microcomputed X-ray tomography, at voxel resolutions ranging from (5.7 micro m)(3) to (11 micro m)(3), to image the proximal epiphyseal growth plates of both male (n = 19) and female (n = 15) rat tibiae, ranging in age from 2 to 25 months. The three-dimensional images were used to evaluate fusion of the epiphyseal growth plate by quantitating the amount of cancellous bone that has bridged across the growth plate. The results suggest that the time course of fusion of the epiphyseal growth plate follows a sigmoidal pattern, with 10% of the maximum number of bridges having formed by 3.9 months in the male tibiae and 5.8 months in the female tibiae, 50% of the maximum number of bridges having formed by 5.6 months in the male tibiae and 5.9 months in the female tibiae, and 90% of the total maximum of bridges have formed by 7.4 months for the males and 6.5 months for the females. The total volume of bridges per tibia at the age at which the maximum number of bridges per tibia has first formed is 0.99 mm(3)/tibia for the males and 0.40 mm(3)/tibia for the females. After the maximum number of bridges (-290 for females, -360 for males) have formed the total volume of bridges per tibia continues to increase for an additional 7.0 months in the males and 17.0 months for the females until they reach maximum values (-1.5 mm(3)/tibia for the males and -2.2 mm(3)/tibia for the females).

Aging↗
PubMed1983

Identification of in-vivo vibration modes of human tibiae by modal analysis.

When attempting to evaluate the mechanical properties of human bones in vivo by mechanical vibration analysis, some essential requirements must be met. A quantitative relation between measured vibration parameters (e.g., natural frequency) and mechanical bone properties must be available, in-vivo vibration modes should correctly be identified and the associated natural frequencies reproducibly and accurately measured, the influence of joints and soft tissues must be known. These problems were addressed by modal analysis (i.e., experimental determination of natural frequencies, mode shapes and damping ratios) of human tibiae in the following situations: 1) dry excised tibiae, 2) fresh excised tibiae, 3) in-vivo tibiae, 4) tibiae in an amputated leg, in different steps of dissection. In the in-vivo measuring conditions used by the authors, the tibia vibration is practically free-free. Two single bending modes (at +/- 270 Hz and +/- 340 Hz, respectively), each of them corresponding with one principal direction for bending, were identified. The difference between the natural frequencies observed in vivo and those of fresh excised tibiae is almost completely caused by the effect of muscles (added mass and damping), whereas joints and skin play only a minor role. Frequency differences between fresh and dry excised tibiae are largely accounted for by the absence of bone marrow in the latter.

Adult↗
PubMed1991

The influence of various calcium and phosphorus levels on tibia strength and eggshell quality of pullets during peak production.

One thousand and eighty DeKalb XL pullets were randomly allocated to nine treatments and arranged in a 3 x 3 factorial to determine the effects of three levels of dietary calcium (2.75, 3.75, and 4.25%) and three levels of dietary available phosphorus (.30, .40, and .50%) on eggshell quality and tibia weight, tibia breaking strength, tibia ash, and bone mineral content of pullets during peak production. Feed consumption increased as dietary calcium or phosphorus increased. Increasing dietary calcium caused a significant linear increase in egg specific gravity, but dietary phosphorus had no significant effect on egg specific gravity. Calcium and phosphorus levels did not significantly affect egg production, body weight, plasma chloride, or phosphorus. Ionized calcium increased significantly as dietary calcium increased. Tibia breaking strength, tibia weight, tibia ash, and bone mineral content increased significantly with increasing dietary calcium. Dietary phosphorus had no significant effect on these parameters. However, when 2.75% calcium was fed, reducing dietary phosphorus significantly decreased tibia weight, tibia ash, and bone mineral content.

Animals↗
PubMed2000

[Treatment of tibia and femur massive defect with pedicled fibula transposition].

OBJECTIVE: To investigate the repairing result for the massive bony defects of upper and middle tibia and lower femur. METHODS: Since 1974, four types of pedicled-fibula transposition were performed to repair the massive bone defect of tibia and femur in 25 cases, which included; 9 cases with benign tumor of upper part of tibia were performed muscle-pedicled fibula transposition and knee fusion after tumor resection; 9 cases with extensive benign tumor or tumoroid lesion of tibia shaft were performed muscle-pedicled fibula transposition and tibia-fibula fusion after tumor resection; 2 cases with extensive benign tumor or tumoroid lesion of middle and lower parts of tibia were performed vascular pedicled fibula transposition and tibia-fibula fusion; 5 cases with benign tumor of distal femur were performed vascular pedicled fibula reversal transposition and knee fusion. RESULTS: After 3 months to 11 years follow-up, 23 cases showed bone healing at 6 months postoperatively. The other 2 cases showed bone healing at 12 months postoperatively. All cases had satisfactory functional rehabilitation. CONCLUSION: Pedicled-fibula transposition is a choice method for repairing massive defects of tibia and femur.

Adolescent↗
PubMed1984

[Congenital angular deformity of the tibia in chick embryo induced by ethane-1-hydroxy-1, 1-diphosphonate (EHDP)].

Congenital angular deformity of the tibia (CADT) is one of the classic inborn errors. The treatment of the disease is very difficult because of insufficient clinical and experimental data and lack of complete experimental model of the disease. The present study is designed to establish a new experimental model of CADT. In vivo experiment: Only one injection of ethane-1-hydroxy-1,1-diphosphonate (EHDP) (4 X 10(-2)-4 X 10(-1) mumol/g egg wt.) was given into the yolk sac of fertile white leghorn egg at 8 days of incubation. The skeletal deformities of the chick embryos were examined during the period of EHDP-administration until hatching. Furthermore, the effect of EHDP was compared with that of its analogs (dichloromethylene diphosphonate: Cl2MDP and inorganic pyrophosphate: PPi) in a similar manner. In vitro experiment: Tibiae from 9-day-old chick embryos were cultured at 37 degrees C for 6 days by roller-tube method in the medium containing EHDP, Cl2MDP or PPi at concentrations of 4-400 microM to measure dry weight and calcium content of the tibiae. The results are summarized as follows. Angular deformity of the tibia in chick embryo was produced in vivo specifically by EHDP-administration compared to its analogs. There existed the critical stage of bone development and the critical dose of EHDP-administration to induce angular deformity of the tibia. The incidence and the severity of the tibial bowing depended on the dose of EHDP-administration. The thinning of periosteal bone collar and retardation of primary bone marrow formation were observed in EHDP-administered tibia. According to 3H-thymidine autoradiographic study, EHDP inhibited DNA synthesis of osteoblast by about 58% after 2 days of administration. The DNA synthesis of chondrocyte was also inhibited by about 20% after 2 days of EHDP-administration. EHDP had a more inhibitory effect on calcification of chick embryonic tibiae than Cl2MDP and PPi at concentration of 40 microM without influencing the dry weight of tibiae in vitro. This new experimental model of CADT offers a significant possibility to elucidate the etiology of this disease.

Abnormalities, Drug-Induced↗
PubMed1994

Influence of the fibula on growth of the rat tibia.

To investigate the effect of the fibula on growth of the tibia in the rat, (1) a sleeve of periosteum was removed from the middle third of the tibia, (2) a length of the fibula was excised, or (3) a sleeve of periosteum was removed from the middle third of the tibia and a length of fibula was also excised. Over a 14 wk experimental period subsequent tibial bone growth was measured on radiographs and compared with unoperated contralateral control tibiae. Procedure (1) had no effect on growth, (2) resulted in 4.2% overgrowth and (3) produced 19.7% overgrowth compared with control tibiae. The failure of overgrowth after periosteal resection from the middle third of the rat tibia argues against the vascular response theory in relation to bone overgrowth. The longitudinal overgrowth after procedure (2) and its further accentuation by procedure (3) suggests that the fibula influences tibial bone growth by exerting a mechanical restraint on it, which is reciprocal to the restraining influence of the tibial periosteum. Overgrowth appears to be facilitated by decompression of the cartilage growth plate of the rat tibia when a sleeve of the periosteum is removed from it, and this suggests a mechanical relationship between the fibrous periosteum and the cartilage growth plate of the tibia. It is concluded that the fibula plays a reciprocal role in regulating tibial bone growth in the rat.

Animals↗
PubMed2005

Finite element analysis of the mouse tibia: estimating endocortical strain during three-point bending in SAMP6 osteoporotic mice.

To support future studies of tibial bending in a murine model of senile osteoporosis (SAMP6), we sought to determine the relationship between applied external bending force and peak endocortical strain in the tibiae of SAMP6 and control SAMR1 mice. The lower hindlimbs of mice were loaded by three-point bending in the lateral-medial plane with a support length of 10 mm. Force-periosteal strain relations were first determined using standard strain gauge methods. Finite-element analysis (FEA) models of the tibia-fibula were generated based on microcomputed tomography images. After choosing appropriate boundary conditions, FEA predictions of periosteal strains were within 15% of measured values. FEA revealed a narrow (3-4 mm) region of the central tibia with well-developed bending strains (tension medially, compression laterally); outside this region, we observed high shear strains. Both the strain gauge data and the finite-element simulations indicated that the tibia of the SAMP6 mouse was 20-25% stiffer than the SAMR1 tibia, consistent with a larger moment of inertia and higher cortical bone modulus. Thus, higher levels of force are required to produce the same target values of strain in the SAMP6 tibia. The ratio of periosteal to endocortical strain in the region of interest was similar for the two mouse strains (1.5-1.6). Based on these ratios, we scaled the strain gauge data to estimate the force-endocortical strain relations for the two mouse strains. In conclusion, FEA, with supporting strain gauge measurements, has provided unique insight regarding the strain environment throughout the tibia during three-point bending in mice.

Animals↗
PubMed1989

Effect of muscle flap coverage on bone blood flow following devascularization of a segment of tibia: an experimental investigation in the dog.

Severe tibial fractures may be associated with soft tissue loss, devascularization of cortical bone, and significant morbidity. Local rotational muscle flap coverage is used to obtain coverage of acute open tibial fractures and to treat chronic osteomyelitis of the tibia. The purpose of this study was to determine (a) the longitudinal and cross-sectional regional blood flow characteristics of the canine tibia and (b) whether a muscle flap was superior to vascularized skin coverage in restoring blood flow to devascularized canine tibial cortex. A 2.5-cm segment of tibia between two standardized osteotomies was devascularized. The segment was replaced anatomically and stabilized with a plate. The animals were divided into two experimental groups: (a) skin coverage (n = 8), and (b) muscle flap coverage (n = 8). Thirty-one days postoperatively Ce141 microspheres were injected to measure bone blood flow. The tibial diaphysis was divided into proximal, middle (devascularized), and distal segments. The unoperated leg was used as a control. In the control tibiae, the middle segment was less vascular than either the proximal or distal segment and no difference between anterior and posterior cortical blood flow was observed. Blood flow to the devascularized segment of tibia was significantly greater when it was covered with a muscle flap (p less than 0.025). The most significant increase in bone blood flow in the muscle flap coverage group versus the skin coverage group occurred in the anterior cortex of the tibia (p less than 0.005). This may be clinically important since the soft tissues over the anterior tibia are commonly deficient following open fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗