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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↗

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↗

PubMed1999

Estimation of defect volume in segmental defects of the tibia and femur.

BACKGROUND: With the advent of modern limb salvage techniques, segmental bone loss in the lower extremity has become more common. METHODS: To aid preoperative planning when dealing with segmental bone loss in the femur and tibia, we performed a cadaveric study to estimate the volume of autogenous or allograft material required to fill defects located in various areas of the bones. RESULTS: The greatest volume was generally required in metaphyseal defects, with an average of 12 cc/cm in the distal femur and proximal tibia, 11 cc/cm in the proximal femur, and 6 cc/cm in the distal tibia. Diaphyseal defects were found to have the least variability with regard to the volume of graft material required for different specimens. Femoral diaphyseal defects required 7 cc/cm and tibial diaphyseal defects required 5 cc/cm. A slightly larger volume of allograft material was needed to fill all defects compared with autograft. CONCLUSION: This method allows one to estimate the amount of graft required for a defect of the femur and the tibia.

Anthropometry↗

PubMed1982

Intraepiphyseal osteotomy for progressive tibia vara: case report and rationale of management.

Tibia vara (Blount's disease) is characterized by two components, the epiphyseal, which is concerned with articular relationships, and physeal/metaphyseal, which may produce angulation of a long bone. Although the initial etiology is not known, it appears that asymmetrical pressure applied to the angulated proximal tibia results in progressive deformity. In the initial stages, medial and posteromedial pressure causes growth retardation of the epiphysis (articular instability) and the physis (tibia vara). Nonsurgical or surgical treatment that relieves the pressure generally permits reconstitution of normal growth. Continued abnormal pressure and shear forces applied to the physis may result in disorderly enchondral ossification and produce a true osteochondrosis, which may lead to permanent physeal arrest. Osteotomy alone to relieve medial pressure may allow the tibia to grow straight, but residual medial epiphyseal compression and joint instability may persist. A case is reported of a 13 1/2 year follow-up of a patient in whom intraepiphyseal osteotomy restored articular congruity without interfering with longitudinal growth. The risks and experimental nature of this procedure are emphasized.

Child↗

PubMed1983

Tibia valga caused by asymmetrical overgrowth following a nondisplaced fracture of the proximal tibial metaphysis.

Tibia valga has been described as a consequence of nondisplaced fractures of the proximal metaphysis of the tibia in children. There has been considerable speculation about the cause of this deformity. The present case is that of a child who developed a valgus deformity of her tibia after the fracture had healed in a normal position. The presence of growth arrest lines in the proximal metaphysis of the tibia demonstrates that the valgus deformity in this patient was caused by overgrowth of the medial portion of the proximal tibial epiphyseal plate.

Bone Diseases, Developmental↗

PubMedDate not supplied

Prophylactic bypass grafting of the prepseudarthrotic tibia in neurofibromatosis.

Nine cases of prophylactic bypass grafting of the prepseudarthrotic tibia in neurofibromatosis were reviewed. The age at operation ranged from 0.9 to 9.2 years. The graft used was variously the opposite tibia, autograft rib, allograft fibula, and allograft bone chips in combination with autograft or allograft. All patients were braced postoperatively. Follow-up ranged from 2.9 to 18.8 years. Allograft bone chips resorbed in every case. All autografts and the one fibular allograft united with the tibia. Three tibias required further procedures to obtain union after development of pseudarthrosis, whereas six remained intact.

Bone Transplantation↗

PubMed1982

Quantitation of regional chondro-osseous circulation in canine tibia and femur.

Regional osseous blood flow (OBF) to various regions of the femur and tibia was measured using radioactively labeled 15-micrometers microspheres injected into the right atrium of neonatal, skeletally immature, and skeletally mature canines. Each bone was divided into as many as 41 anatomically distinct sections to assess developmental and regional comparisons in OBF. A quantitative decrease in OBF with increasing chondro-osseous maturity was observed for both the whole bones as well as many regions within a given bone. This was particularly significant in the tibia in which OBF to the mature tibia was much lower than in the immature tibia or even the mature femur. In the immature and neonatal bones, the epiphyseal and metaphyseal regions nearest the physes had the highest flow. The physis had a statistically significant high flow rate. Furthermore, regional differences in OBF correlated well with known regional functions in both endochondral and membranous (periosteal) bone formation. OBF tended to be greater in regions of greater metabolic activity associated with hematopoiesis and endochondral osteogenesis. OBF values correlated well with regional predilections of various diseases such as acute hematogenous osteomyelitis prior to skeletal maturity and osseous metastases, and, by extrapolation, strongly support a physiological reason for delayed healing and nonunion in tibial fractures in the skeletally mature human.

Aging↗

PubMed1997

Dynamics of neurons controlling movements of a locust hind leg II. Flexor tibiae motor neurons.

Imposed movements of a proprioceptor that monitors the relative position of the tibia about the femur, the femorotibial chordotonal organ (FeCO), evoke resistance reflexes in the motor neurons that control the movements of the tibia of the locust. The response dynamics of one pool of motor neurons, the flexor tibiae motor neurons, which are located in three groups (anterior, lateral, and posterior), have been analyzed by the Wiener kernel method. First- and second-order kernels that represent the linear and nonlinear responses, respectively, were computed by a cross-correlation between the intracellularly recorded synaptic responses in the motor neurons and the white noise stimulus applied to the FeCO, and were used to define the input-output characteristics of the motor neurons. The posterior fast, intermediate, and slow and the anterior fast and intermediate flexor tibiae motor neurons had biphasic first-order kernels with initial negative phases, indicating that they are velocity sensitive. The falling phases of the kernels had distinct shoulders, indicating that the responses of the motor neurons also had delayed low-pass components, i.e., position sensitivity. The anterior slow flexor motor neuron had a monophasic, low-passed, first-order kernel, indicating that it is position sensitive. The linear component of the motor neuron responses, predicted by convolving the first-order kernels with the stimulus signal, strongly resembled the actual response, whereas the second-order nonlinear component was small, particularly at > 10 Hz. The power spectra of the fast motor neurons showed that they had the highest cutoff frequencies (at > 8 Hz), whereas the slow flexor motor neurons had a gradual roll-off at 1 Hz. The intermediate flexor motor neuron had an intermediate cutoff frequency of approximately 2-3 Hz. The linear responses of the flexor motor neurons could be decomposed into low- and high-frequency components. The high-frequency components (> 10 Hz) were velocity dependent and linear, whereas the low-frequency components (< 10 Hz) were position dependent and nonlinear. The nonlinearity was a signal compression (or half-wave rectification). The results show that although the flexor motor neurons receive many common inputs during FeCO stimulation, each individual has specific dynamic response properties. The responses of the motor neurons are fractionated so that a given individual within the pool will respond best to position, whereas others will respond better to velocity. Likewise, some motor neurons respond best at low frequencies, whereas others respond best at higher frequencies of stimulation.

Animals↗

PubMedDate not supplied

Radiographic and histologic analyses of stress fracture in rabbit tibias.

Sequential changes in remodeling of the internal structure of the tibia caused by controlled, excessive jumping and running were studied in 20 rabbits. Vascular changes and circulatory disturbances within the cortical bone occurred before osteoclastic resorption. Degeneration and necrosis of osteocytes due to circulatory disturbances also occurred. Periosteal new bone formation, found at and after 12 days of the experiment, was a compensatory reaction to support the tibia weakened by accelerated osteoclastic resorption. Small cracks appeared at the cement line and developed through the neighboring cement line of the haversian systems. At 21 days, incomplete fracture of the tibial cortex was found in two rabbits. Complete fracture through one side of the cortex was seen in one animal at the 50th day of the experiment. In this study, however, most of the tibias did not have visible fracture lines after a period of stressful exercise. This result suggests that most tibias adapt to changes in stress requirements through proper internal remodeling so that a complete fracture does not occur.

Animals↗

PubMedDate not supplied

Pathomechanics of posterior sag of the tibia in posterior cruciate deficient knees. An experimental study.

This study was an investigation of the pathomechanics of posterior sag of the tibia in knees with posterior knee instability caused by PCL deficiency. By using fresh cadaver knees, the authors hoped to define the relationship of the posterior joint capsule and the medial and lateral collateral ligaments (MCL, LCL) with posterior knee instability in the PCL deficient knee. Thirty newtons of posterior stress were applied to the knees to simulate postoperative conditions. Roentgenographic methods were then used to evaluate posterior sag and change in the distance between the origin and insertion of the PCL. Strain gauges were used to measure the actual strain of the PCL and the collateral ligaments. The PCL, the posterior capsule, and the medial and lateral collateral ligaments were sequentially divided and the above measurements were then repeated in the same way, using 30 N of applied posterior stress. When only the PCL was cut, posterior sag and medial rotation of the tibia occurred with increasing severity as flexion increased. No sagging or rotation of the tibia was observed at full extension in the knees that had isolated PCL "injury". When the posterior capsule was sectioned, no significant changes were noted in the severity of the sag or the rotation. When the MCL or LCL was divided in a PCL deficient knee, greater sag occurred with flexion and a significant sag was observed even at full extension. The MCL "injury" was associated with increased medial rotation, whereas LCL "injuries" were associated with lateral rotation of the tibia.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMedDate not supplied

Tensile properties of the human femur-anterior cruciate ligament-tibia complex. The effects of specimen age and orientation.

The structural properties of 27 pairs of human cadaver knees were evaluated. Specimens were equally divided into three groups of nine pairs each based on age: younger (22 to 35 years), middle (40 to 50 years), and older (60 to 97 years). Anterior-posterior displacement tests with the intact knee at 30 degrees and 90 degrees of flexion revealed a significant effect of knee flexion angle, but not of specimen age. Tensile tests of the femur-ACL-tibia complex were performed at 30 degrees of knee flexion with the ACL aligned vertically along the direction of applied tensile load. One knee from each pair was oriented anatomically (anatomical orientation), and the contralateral knee was oriented with the tibia aligned vertically (tibial orientation). Structural properties of the femur-ACL-tibia complex, as represented by the linear stiffness, ultimate load, and energy absorbed, were found to decrease significantly with specimen age and were also found to have higher values in specimens tested in the anatomical orientation. In the younger specimens, linear stiffness (242 +/- 28 N/mm) and ultimate load (2160 +/- 157 N) values found when the femur-ACL-tibia complex was tested in the anatomical orientation were higher than those reported previously in the literature. These values provide new baseline data for the design and selection of grafts for ACL replacement in an attempt to reproduce normal knee kinematics.

Age Factors↗

PubMed1995

The influence of joints and soft tissue on the natural frequency of the human tibia using the impulse response method.

The influences of the joints adjacent to the human tibia, the surrounding soft tissue and the fibula on the vibrational parameters of the tibia (that is natural frequency, mode shape and damping ratio) are in need of clarification. Using five cadaveric human legs, the resonant frequency and damping ratio were measured with an accelerometer placed on the medial tibial condyle while the medial malleolus was impacted by an impulse hammer. The legs were subsequently dissected and the measurements were made in six conditions. The mode shape was obtained by use of modal analysis. Hammer impacts were given at 15 points along the three surfaces of the tibia, while an accelerometer was attached to the surface of the medial malleolus. Resonant frequencies ranged from 275 to 405 Hz in the intact specimens and successively increased with removal of the skin, muscles and foot, and then decreased with the removal of the femur and the fibula. Damping ratios successively decreased. The transitional pattern of natural frequencies was similar to that of the resonant frequencies. The mode shape represented the first bending mode and it corresponded to the condition of the tibia in which the proximal and distal ends of the bone were free.

Aged↗