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PubMed1990

Modelling human tibia structural vibrations.

Mode shapes and natural frequencies of human long bones play an important role in the interpretation, prediction and control of their dynamic response to external mechanical loads. This paper describes an experimental and theoretical study of free vibrations in an excised human tibia. Experimentally, seven tibial natural frequencies in the range 0-3 kHz were identified through measured structural transfer functions. Theoretically, a beam type Finite Element model of a human tibia is suggested. Unknown parameters in this model are determined by a Bayesian parameter estimation approach, by which very fine model/observation-accordance was achieved with realistic parameter estimates. A sensitivity analysis of the model confirms that the human tibia in a vibrational sense is more uniform than its complicated geometry would immediately suggest. Accordingly, two simple tibia models are identified, based on uniform beam theory with inclusion of shear deformations.

Biomechanical Phenomena↗

PubMed1987

Permeability of cortical bone of canine tibiae.

Movement of interstitial fluid in cortical bone is considered one of the important mechanisms affecting bone remodeling and fracture healing. To better understand such interstitial fluid movement, the hydrostatic permeability of cortical bone of the canine tibia was measured in this study. It was found that age has significant influence on permeability. The cortical bone permeability of puppy tibiae is six times higher than that of adult tibiae. Adult tibial cortex is impermeable unless the superficial layer of the periosteal cortex is removed. The permeability differs between regions and locations of the tibia. The pathways for such extravascular interstitial fluid movement were also identified to be primarily the haversian and Volkmann's canals and secondarily the canalicular and lacunar spaces. The high permeability of their cortical bone may explain the increase in periosteal new bone formation seen in puppies when a venous tourniquet is applied.

Aging↗

PubMed1993

Evaluation of hollow and full stems implanted in the rabbit tibia: preliminary results.

Full and hollow stems were implanted in the right and left tibiae of five rabbits to study the effects of the implant shape on revascularization and remodelling of the bone after 6 months. No significant difference of periosteal and endosteal circumference was observed when the left and right tibiae of each group were compared. Medullary area was, not surprisingly, significantly smaller in the full stem implanted tibiae. The cortical bone area result was significantly higher in the hollow stem group. In hollow stems, vessels were present both inside and outside the implant with connections through the holes of the implant. The observed differences of cortical bone area can be explained in terms of increased vascular spaces inside the cortical bone of full stem implanted tibiae. This supports the hypothesis that hollow implants provide more space for medullary revascularization and are consequently capable of inducing less endosteal remodelling. Cementless prostheses rely for mechanical fixation on a large interface of the implant with bone. Two factors, i.e. revascularization of the medullary canal and stiffness of the stem, can have a relevant effect on the quality of interface. This non-weight-bearing model suggests the relevance of vascular factors.

Animals↗

PubMed1994

Morphology-mechanical property relations in trabecular bone of the osteoarthritic proximal tibia.

Alteration of morphologic and mechanical properties of trabecular bone in the osteoarthritic proximal tibia may be a contributing factor in tibial component loosening. To explore this issue, the authors performed tissue property measurements, morphologic analysis, and mechanical testing of subchondral, epiphyseal, and metaphyseal trabecular bone specimens retrieved from six human proximal tibias exhibiting a range of medial unicondylar osteoarthritic degeneration. Apparent density in the proximal tibia was altered according to varus misalignment and medial subluxation associated with medial osteoarthritis of the knee. In subchondral bone, a decrease in tissue mineralization contributed to a significant reduction in axial mechanical properties with degenerative disease (P < .0005). In epiphyseal and metaphyseal bone, trabecular thickness and the number of trabeculae increased linearly with volume fraction, providing a power law relationship between axial elastic modulus and apparent density (R2 = .84). Average elastic properties of the tibial epiphysis and metaphysis were not reduced by degenerative disease (P < .05). The results suggest that absolute minimization of tibial resection might not be an optimal strategy for tibial component fixation and that mechanical properties of the tibial resection surface are more homogeneous in planes parallel to the joint surface than in a plane normal to the longitudinal axis of the tibia.

Aged↗

PubMed1994

In vivo measurements of the phase constants of transverse mechanical waves in a human tibia from 100 to 1000 Hz.

This paper contains the details of a new technique for measuring the mechanical phase constants of transverse waves in human tibia, in vivo. The measurements are made in the frequency range from 100 to 1000 Hz. The importance of these measurements is that healthy tibia has quite small phase delays along the bone at these frequencies. On the other hand, a fractured tibia has a large phase delay at the fracture site. This paper establishes a set of typical phase delays for a range of tibia so that subsequent measurements on fractured patients can be interpreted. It contains a description of the method of measuring the phase delay and a detailed analysis of errors. In particular, it includes an account of the phase delay through the soft tissues as well as the bone and how the former can be eliminated. It is not an exhaustive account of this topic but contains sufficient results to show that the measurements can be made relatively easily. Finally, there is a theoretical model which can be used to predict the phase shift. However, in order to use the model various other measurements are necessary and a direct measurement of phase is easier than using a model.

Electric Impedance↗

PubMed1990

Terminal differentiation of osteogenic cells in the embryonic chick tibia is revealed by a monoclonal antibody against osteocytes.

Monoclonal antibodies against the surface of embryonic osteogenic cells have been used to characterize the sequence of transitions involved in the osteoblastic cell lineage. These previous data identified distinct cell stages within the osteogenic lineage, but were incomplete. To further refine and extend these observations, additional monoclonal antibodies were generated against the surface of osteogenic cells by immunizing mice with a heterogeneous population of chick embryonic bone cells. Supernatants from growing hybridoma colonies were immunohistochemically screened against frozen sections of stage 35 (day 9.5) chick tibiae. One cell line, SB-5, which secretes an antibody against the surface of osteogenic cells was successfully cloned, stabilized, and immortalized. Studies on the developmental progression of osteogenesis in the embryonic chick tibia reveal that cells within the lineage stages from Pre-Osteoblast to Secretory Osteoblast were never observed to react with antibody SB-5 at any time. By contrast, strong cell surface immunoreactivity was present on mature osteoblastic cells as they became Osteocytes. Furthermore, in cultures of osteogenic cells derived from embryonic calvaria or tibiae, cells possessing the SB-5 antigen on their surface displayed a morphology remarkably similar to that of Osteocytes found in situ. Double immunofluorescent staining of developing chick tibiae with SB-5 and SB-2, a monoclonal antibody directed against the surface of Secretory Osteoblasts, indicates that these cells proceed through an intermediate lineage step before becoming terminally differentiated Osteocytes. This transitory cell state is characterized by the simultaneous cell surface binding of antibodies SB-2 and SB-5, and is referred to as the Osteocytic Osteoblast stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1996

Bone marrow capacity for bone cells and trabecular bone turnover in immobilized tibia after sciatic neurectomy in mice.

Trabecular bone turnover and bone marrow capacity for the development of bone cells in the tibia were assessed after sciatic neurectomy (NX) in mice. The right hindlimbs of 6-week-old DDY mice were neurectomized and left hindlimbs were sham-operated and served as NX controls. Histomorphometrical analyses of the trabecular bone of the proximal tibia demonstrated the initial decrease in bone formation rate for the first 14 days and the subsequent increase in osteoclast surface for the next 14 days. The number of adherent stromal cells per tibia obtained for the NX limbs was reduced on days 7 and 10 postsurgically, and then recovered on day 12. However, the alkaline phosphatase activity of the cells was persistently depressed. The formation of osteoclast-like multinucleated cells in the marrow cultures obtained from NX limbs at days 10, 12, and 14 showed a significant increase in the medium containing parathyroid hormone (PTH). The number of colonies cultured for colony forming units-fibroblastic (CFU-f) that developed from the marrow cells did not differ in the NX and the contralateral limbs at any time during the period. On the other hand, the number of colonies cultured of colony forming units for granulocytes and macrophages (CFU-GM) was markedly increased for both the NX and the contralateral tibiae at days 12 and 14. This study clearly demonstrates that there are two stages in the development of osteopenia after NX. During the first 14 days, trabecular bone formation and number of marrow stromal cells are reduced. In the second 14 day period, the trabecular osteoclast number is increased and osteoclast formation from the bone marrow cells is enhanced in the presence of PTH. However, neither the CFU-f nor the CFU-GM assay could identify the changes in osteogenic or osteoclastogenic potential of the bone marrow. These in vitro assays provide limited information on the shifts in bone marrow cell lineages and the local environment producing osteopenia in the immobilized limb in vivo.

Alkaline Phosphatase↗

PubMed1997

Tibialis anterior turnover flap coverage of exposed tibia in a severely burned patient.

A case report of a longitudinally split tibialis anterior turnover flap reconstruction of an exposed tibia in a burn patient is presented here. The patient had sustained deep partial- and full-thickness burns to 70 per cent of his total body surface area (TBSA), resulting in an exposed left patella and upper two-thirds of the left tibia. Although full thickness loss of skin occurred on the left lower leg, no muscle trauma was sustained. Reconstruction was therefore deemed possible using local muscle tissue to provide transposed flap coverage. A gastrocnemius muscle flap was used to cover the exposed patella and superior aspect of the tibia. A portion of the tibialis anterior muscle was split longitudinally and turned over medially to cover the remaining exposed tibia. The advantages offered by this infrequently used flap include technical simplicity, reliability, minimal donor site dysfunction and the allowance of future use of the soleus flap. The tibialis anterior turnover flap may therefore have wide applicability for reconstruction of the severely burned lower extremity.

Accidents, Traffic↗

PubMed1994

Bone mineral distribution of the proximal tibia in gonarthrosis assessed in vivo by photon absorption.

Regional bone mineral density (BMD, g/cm2) of the proximal tibia including the subchondral plate was measured in vivo by dual photon absorptiometry (DPA). Twenty-one women and six men with gonarthrosis (GA) were examined. Twenty-four healthy women served as controls for the women. The precision error of the BMD measurements ranged from 1.4-3.7% depending on the region measured. Subchondral BMD correlated significantly to the radiologic stage (P < 0.05). Compared to the controls, BMD of the subchondral plate, BMD of the medial condyle, the medial to lateral distribution ratio of subchondral BMD and the ratio between BMD of the subchondral plate and of the immediately underlying region were significantly increased in patients with predominantly medial GA (P < 0.05-0.0001). The BMD of the lateral condyle was lower in GA patients than in controls (P < 0.05). In patients with unilateral GA, the above-mentioned changes were found in the affected tibia compared to the normal knee in the same individual (P < 0.05). In contrast to any of the patients with varus deformity, the two patients with valgus deformity had higher BMD of the lateral condyle than of the medial. No differences in BMD of the distal forearm or the ultradistal region of the proximal tibia were found between the GA patients and the controls. The study shows that regional bone changes of the proximal tibia in GA can be measured precisely and noninvasively in vivo by DPA.

Absorptiometry, Photon↗

PubMed2002

Effect of calcium supplementation on bone dynamics of the maxilla, mandible and proximal tibia in experimental osteoporosis.

The effect of calcium supplementation on the bone dynamics in the hard palate of the molar region (maxilla), mandible and proximal tibia in experimental osteoporotic rats was examined. Ninety ovariectomized (OVX) and 45 sham-OVX Wistar female rats were used in this study. All the rats received surgical operation at 6 weeks of age. Ovariectomized rats were fed on a low calcium diet (0.02%) for 12 weeks post-operation, and then randomly divided into the two following groups. One group was fed on high calcium diet (2.30%) (OVX-HCa) and the other group was remained on the low calcium diet (OVX-LCa). Sham-OVX rats were fed on regular calcium diet (1.15%) during the experimental period (Sham-OVX). Histomorphological analysis was carried out from 12 to 32 weeks post-operation. On undecalcified thin section, bone volume, eroded surface, osteoid surface and bone formation rate were calculated for cortical bone of the maxilla, and for cancellous bone of the mandible and proximal tibia. In the OVX-LCa group, compared with the Sham-OVX group, decrease of the bone volume and increase of the bone resorption and formation parameters were detected throughout the observation periods. In the OVX-HCa group, compared with the OVX-LCa group, increase of the bone volume and temporarily increased parameters of bone formation at 1 week after feeding on high calcium diet were observed in the maxilla, but these changes were not observed in the mandible and proximal tibia. Moreover, the bone resorption and formation parameters in the maxilla, mandible and proximal tibia in the OVX-HCa group became equivalent to the Sham-OVX levels with the passage of time.

Analysis of Variance↗

PubMed2000

Medulloscopy of the tibia: initial report of a new technique.

This study shows the ability of 3 standard endoscopic instruments to access the length of the intramedullary canal through a technique that we have termed "medulloscopy." Cadaveric studies were performed to determine the dimensions of the proximal tibia and the relative abilities of a knee arthroscope, a hip arthroscope, and a flexible rhinolaryngoscope to visualize the length of the intramedullary canal of the tibia. The 3 endoscopes were able to access the length of the intramedullary canal in the following proportions: 19.1% +/- 1.0% for the knee arthroscope, 29.1% +/- 3.8% for the hip arthroscope, and 84.1% +/- 1.8% for the flexible scope (P <.05). The proximal aspect of the intramedullary canal of the tibia can be visualized with standard knee and hip arthroscopic equipment. A flexible rhinolaryngoscope was required to access the distal tibia. Further studies are needed to determine the specific indications for intramedullary arthroscopy.

Aged↗

PubMed2002

The proximal tibia donor site in cleft alveolar bone grafting: experience of 75 consecutive cases.

BACKGROUND: The optimum donor site for cleft alveolar bone grafting is still debated. Donor site morbidity is an important factor in deciding the site for harvest of cancellous bone. Use of the proximal tibia as donor site is associated with few complications. The occurrence of a proximal tibia fracture following cancellous bone harvest from this site, prompted a review of the last 75 consecutive cases carried out at our unit. MATERIAL AND METHOD: The medical notes of 75 consecutive patients undergoing cleft alveolar bone graft were reviewed and postal questionnaires were sent to patient's parents and family physicians. The review focused on donor site morbidity. RESULTS: Fracture of the proximal tibia, a hitherto unreported complication, occurred in two out of 75 cases (2.7%) within our series. Post-operative mobilization was achieved rapidly with normal joint function and donor site healing progressed satisfactorily in all cases. In 1 out of 75 cases the graft was repeated at a later date due to recipient site infection. The incidence of other morbidity was low with most representing local complications only. Length of hospital stay was 3 days (range 2-5 days). CONCLUSION: Based on our findings we feel that the proximal tibia offers a reliable site for harvest of sufficient quantities of good quality cancellous bone. Recommendations are made as to the technique of bone harvest, to minimize the fracture risk.

Adolescent↗

PubMedDate not supplied

[Disruption of the arteria nutricia tibiae by reamed and unreamed intramedullary nailing. Study of the vascular architecture of the human tibial intramedullary cavity].

AIM: By reason of the pseudarthrotic healing of fractures due to vascular complications after reamed and unreamed intramedullary nailing, the intraosseous course and branching of the tibial nutrient artery and its impairment by nailing procedures needs an actual analysis. METHOD: The nutrient vessel of 24 tibiae taken from fresh corpses were prepared by injection of Technovit and lead oxide. After this procedure the medullary cavities of 12 bones were opened by a frontal cut. These specimens were subjected to routine maceration. The other 12 tibiae were naed with the unreamed (6) and the reamed nailing (6) techniques. X-rays were also taken routinely. RESULTS: After penetration of the tibial compact bone the main trunk of the nutrient vessel runs through a perforated osseous tunnel (pars tecta arteriae nutriciae tibiae). At its end the vessel divides into a descending branch (obligate) and two ascending branches (facultative). The descending branch lies near to the centromedial region of the medullary cavity which is termed as the pars liberal arteriae nutriciae tibiae. All branches pass through supporting horizontal osseous lamellas. Due to this topography the reamed nailing technique destroyed the nutrient vessel completely in all specimens. In contrast to this observation the unreamed nailing destroyed the vessel completely only in 1 (16.7%) and partially in 3 (50%) bones; 2 (33.3%) specimens exhibited no destruction of the vessel. CONCLUSION: The unreamed as well as the reamed nailing technique can destroy the intramedullary course of the tibial nutrient artery. Fractures as well as displacement osteotomies or corticotomies are able to diminish the medullary blood supply seriously, if they are localised within the area of the tactic an of the tibial nutrient artery.

Aged↗

PubMed2001

Evaluation of a predictive model for implant surface topography effects on early osseointegration in the rat tibia model.

STATEMENT OF PROBLEM: Alterations in commercially pure titanium (cp Ti) implant surface topography can be made to increase bone formation or the interfacial shear strength of bone at the functioning implant. It is not known whether these 2 goals are congruent or mutually exclusive. PURPOSE: The aim of this study was to determine the effect of implant surface topography parameters of calculated biomechanical significance on the process of bone formation in a rat tibia model of osseointegration. MATERIAL AND METHODS: Implants (cp Ti grade IV) were machined and subsequently treated by grit blasting or grit blasting and 6.4 mol/L HCl. Measurements of surface roughness were made by atomic force microscopic analysis of similarly treated titanium disks. Cleaned and sterilized implants (12 machined, 12 with nonideal pit morphology, 12 with ideal pit morphology) were placed into the tibiae of 400-g male Wistar rats by using a series of drills, irrigation, and a self-tapping procedure. After 3 weeks, tibiae were harvested and processed and embedded in methyl methacrylate resin. Polished sections were examined by backscatter electron microscopy, and the percentage implant surface contacting bone was measured with the Scionics PC image analysis program. RESULTS. The implants possessing a proposed ideal pit morphology supported significantly greater bone formation at the implant surface (54% +/- 7% bone-to-implant contact [P<.003]) than the nonideal pit morphology (40% +/- 15%) or machined surfaces (34% +/- 6%). CONCLUSION: Implant surfaces with a proposed ideal pit morphology (which possess a calculated biomechanical significance) enhanced bone formation at early periods after placement in the rat tibia model.

Animals↗

PubMed2000

Variability in XRF-measured tibia lead levels.

A few studies have examined the variability in 109Cd-based K-shell x-ray fluorescence (KXRF) bone lead measurements from replicate measurements made either at the same time or over a period of time, and one of these studies has shown that the uncertainty in an individual measurement is an underestimate of the standard deviation of replicate measurements. Variability in KXRF tibia lead measurements was assessed from ten cadaver intact legs, from the bare tibiae dissected from nine of these legs, and from four in vivo volunteers. Cadaver legs underwent replicate measurements on multiple occasions. In vivo volunteers underwent single measurements of the left tibia monthly for one year. Average tibia lead levels in the cadaver legs and in vivo volunteers ranged from 6 to 50 and from 6 to 13 microg Pb per g of bone mineral respectively. The factors influencing the standard deviation of replicate measurements were investigated. Both cadaver and in vivo measurements confirmed that the uncertainty in an individual measurement is an underestimate of the standard deviation of replicate measurements, suggesting a methodological deficiency probably shared by most current 109Cd-based K-shell XRF lead measurement systems.

Adult↗

PubMed1996

Femur lengthening with a vascularized tibia bone flap.

A vascularized tibial bone flap based on a single nutrient vessel has been previously proposed for use in long-bone reconstruction. While the routine use of the tibia for donor bone tissue is precluded by its essential weight-bearing function, in select cases it provides a useful alternative to standard donor bone sources. Cadaver dissection was performed to confirm the endosteal and periosteal vascular anatomy of the tibia. The presence of a consistent nutrient vessel was confirmed. Selective dye injection demonstrated a dual cortical blood supply based on both the endosteal nutrient vessel and multiple periosteal perforator vessels. Inclusion of both vascular supplies maximizes perfusion of bone and periosteum, thus potentially optimizing bone healing and osseous union. Based on these findings, the vascularized tibial bone flap was applied to a clinical case. A 45-year-old male veteran sustained a right proximal femur fracture in a motor vehicle accident. Multiple attempts at fusion with open reduction, internal fixation, grafting, and nonvascularized fibular onlay strut with cerclage wires were all unsuccessful. The patient presented with a chronic right femur nonunion with painful pseudoarthrosis; frozen knee joint; and an internally rotated, 20.3-cm shortened, nonfunctional lower limb. Femur length proximal to the nonunion was less than 15 cm. A maximum amputation stump length is recommended for optimal prosthetic function. A 15-cm pedicled tibial bone flap based on the posterior tibial endosteal and periosteal vascular supply was reversed and plated to the proximal femur to provide a stump of adequate length to optimize prosthetic fitting and function. The tibia is essential for normal weight-bearing, but in select cases may be sacrificed for use in long-bone reconstruction. Expanded use of tibial vascularized allografts in long-bone reconstruction may be made possible following future development of effective and safe immunosuppressive therapy. Transfer based on the posterior tibial pedicle, which includes the endosteal nutrient vessel as well as the periosteal supply via the tibialis posterior muscle, maximizes bone perfusion. The pedicle is of sufficient length to be used for positioning the tibia in the thigh or for free transfer to distant sites.

Amputation Stumps↗

PubMed1998

Cortical bone blood flow in loose and tight fitting locked unreamed intramedullary nailing: a canine segmental tibia fracture model.

OBJECTIVES: To quantitatively determine the extent to which loose and tight fitting unreamed, locked intramedullary nails devascularize cortical bone and to determine their effect on early strength of union. DESIGN: A 2.5-centimeter segment of devascularized diaphyseal bone was created in the tibiae of twelve skeletally mature mongrel dogs by means of two standardized transverse osteotomies. Stabilization of the tibia was achieved with either a 5.0-millimeter (n = 6) or a 6.5-millimeter (n = 6) unreamed, locked intramedullary nail. Bone blood flow was assessed using laser Doppler flowmetry. Bending stiffness and load to failure were determined for each healed tibia. RESULTS: At the conclusion of the nailing procedure, the overall tibial blood flow was reduced by 58 percent and 72 percent for the 5.0-millimeter and 6.5-millimeter nail groups, respectively (p = 0.001, p = 0.00004). Perfusion was reduced to a greater extent in the tightly fitting nail group (p = 0.017). At eleven weeks postnailing, cortical perfusion increased in both the 5.0-millimeter and the 6.5-millimeter nail groups (p = 0.005, p = 0.002, respectively). Perfusion increased to a higher level in the loosely fitting nail group (p = 0.007). Biomechanical properties of the healed tibiae, including bending stiffness in two planes and load to failure, were similar in the two experimental groups (p = 0.42, p = 0.09, p = 0.34). DISCUSSION: Our results demonstrate that a loose fitting nail spared cortical perfusion at the time of nail insertion more than did a canal filling nail and allowed more complete cortical reperfusion at eleven weeks postnailing. The results of this study have implications for the treatment of severe tibial shaft fractures in which the blood supply is significantly compromised.

Animals↗

PubMedDate not supplied

High pressure pulsatile lavage of contaminated human tibiae: an in vitro study.

OBJECTIVE: This study was designed to examine the effect of high pressure pulsatile lavage (HPPL) on bone destruction and propagation of bacteria in experimentally contaminated human tibiae. METHODS: Using an in vitro model, nine human tibiae from above-knee amputations were tested. A mid-diaphyseal tibial shaft fracture was created, and each end of the fracture was contaminated with bacteria (six tibiae with Staphylococcus aureus, three tibiae with Escherichia coli). The proximal end was designated as the control and the distal end was the test site. The test site was debrided by HPPL (seventy pounds/square inch, 1,200 milliliters/minute, 1,050 cycles/minute) with three liters of normal saline, whereas the control site did not receive any form of irrigation. Serial sections at increasing distance from the fracture site were cultured and the numbers of bacterial colony-forming units (CFUs) were determined at each level. The degree of macroscopic architectural change in each serial section was graded on an ordinal scale. RESULTS: Analysis of culture data revealed a reproducible pattern of bacterial propagation into the intramedullary canal. Peak bacterial seeding occurred at two to three centimeters from the fracture site (p = 0.023, Wilcoxon signed rank test). The degree of bone destruction varied proportionally with the depth into the canal and was found to be predictive of the extent of bacterial propagation determined by culture data. CONCLUSION: In an in vitro model of a contaminated fracture, HPPL resulted in bacterial seeding into the intramedullary canal and significant damage to the architecture of the bone. These observations might have clinical significance.

Bone and Bones↗