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At least 199 records · Page 11Linked to original sources

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↗

PubMed2001

Anterior positioning of tibia during motion after anterior cruciate ligament injury.

PURPOSE: The purpose of this study was to describe the sagittal tibial translation and EMG activity of muscles v. medialis and lateralis, gastrocnemius, and hamstrings, during common locomotion, in patients with an anterior cruciate ligament deficiency (ACL-def) and uninjured controls. METHODS: In 12 ACL-def patients and 17 controls, sagittal tibial translation was registered with the CA-4000 electrogoniometer during level walking, cutting, and stair walking. Tibial position at each flexion angle was expressed relative to the femuro-tibial position at passive knee extension. EMG activity, measured with ME-4000, was normalized to the individual maximum isometric voluntary contraction for each muscle. RESULTS: During the weight-bearing phase of motion, the tibia was anteriorly positioned in all legs. In the injured leg, the tibia translated more rapidly to an anterior position that was maintained for a longer time during the gait cycle. In the noninjured knees, motions with increased load lead to an increased anterior tibial translation in contrast to the injured knees, where the maximum displacement was already reached during level walking. The quadriceps and gastrocnemius muscles were simultaneously active during stance phase. Hamstrings were mainly active when the knee was close to extension and translation increased in spite of this activity. CONCLUSIONS: The mechanism of the anterior positioning of tibia is qualitatively similar in the normal and the injured knee, but that position is obtained much further forward in the ACL deficient knee. Quadriceps and gastrocnemius muscles seem to work synergistically to stabilize the knee by maintaining the anterior position of tibia during weight-bearing motion. The role of hamstrings to restrict anterior translation is questioned.

Adolescent↗

PubMed2002

Tibia valga due to focal fibrocartilaginous dysplasia: case report.

Focal fibrocartilaginous dysplasia is a rare benign entity, previously described as a factor responsible for causing tibia vara at the walking age. We report here the case of a child with tibia valga due to focal fibrocartilaginous dysplasia of the lateral part of the proximal tibia. To our knowledge, this is the first observation of a lesion located in the lateral proximal tibia. Clinical, radiographic and magnetic resonance imaging surveillance was performed. Spontaneous resolution of the lesion with correction of the angular deformity did occur.

Fibrous Dysplasia of Bone↗

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↗

PubMed1981

The treatment of osteomyelitis of the tibia with sodium salicylate. An experimental study in rabbits.

Osteomyelitis was induced in the tibiae of rabbits by injecting a suspension of Staphylococcus aureus and sodium tetradecylsulphate, a sclerosing agent. These rabbits were then divided into two groups: one group remained untreated and the other was fed a diet containing sodium salicylate. Two and four weeks after induction of osteomyelitis the tibiae taken from untreated rabbits with osteomyelitis and incubated in vitro released significantly more prostaglandin E and F than the control uninjected or uninfected tibiae. Tibiae taken from rabbits treated with sodium salicylate showed minimal radiographic changes and a significantly decreased release of prostaglandin E and F compared to the untreated rabbits. Prostaglandins are known to be potent bone resorbing agents and the results of this study suggest that they may also be involved in the destruction of bone which is characteristic of osteomyelitis. The treatment of rabbits with osteomyelitis using anti-inflammatory drugs, which block synthesis of prostaglandins, in addition to antibiotics, may prevent the destruction of bone and possible sequestration thereby decreasing the risk of chronic disease.

Animals↗

PubMed1997

A more accurate method of measurement of angulation after fractures of the tibia.

Accurate measurement of the alignment of the tibia is important both clinically and in research. The conventional method of measuring the angle of malunion after a fracture of the shaft of the tibia is potentially inaccurate because the mechanical axis of the normal bone may not pass down the centre of the medullary canal. An alternative method is described in which a radiograph of the opposite tibia is used as a template. A sample of 56 sets of standard radiographs of healed fractures of the shaft of the tibia was evaluated. The 95% limits of agreement between this and the conventional method were wide, being -6.2 degrees to +5.5 degrees for coronal angulation and -6.7 degrees to +8.1 degrees for sagittal angulation. These results suggest that the conventional method is inaccurate. The new method has good inter- and intraobserver reliability.

Bone Malalignment↗

PubMed1999

Prosthetic reconstruction for tumours of the distal tibia and fibula.

We have carried out prosthetic reconstruction in six patients with malignant or aggressively benign bone tumours of the distal tibia or fibula. The diagnoses were osteosarcoma in four patients, parosteal osteosarcoma in one and recurrent giant-cell tumour in one. Five tumours were in the distal tibia and one in the distal fibula. The mean duration of follow-up was 5.3 years (2.0 to 7.1). Reconstruction was achieved using custom-made, hinged prostheses which replaced the distal tibia and the ankle. The mean range of ankle movement after operation was 31 degrees and the joints were stable. The average functional score according to the system of the International Society of Limb Salvage was 24.2 and five of the patients had a good outcome. Complications occurred in two with wound infection and talar collapse. All patients were free from neoplastic disease at the latest follow-up. Prosthetic reconstruction may be used for the treatment of malignant tumours of the distal tibia and fibula in selected patients.

Adolescent↗

PubMed2000

Tibiofemoral movement 1: the shapes and relative movements of the femur and tibia in the unloaded cadaver knee.

In six unloaded cadaver knees we used MRI to determine the shapes of the articular surfaces and their relative movements. These were confirmed by dissection. Medially, the femoral condyle in sagittal section is composed of the arcs of two circles and that of the tibia of two angled flats. The anterior facets articulate in extension. At about 20 degrees the femur 'rocks' to articulate through the posterior facets. The medial femoral condyle does not move anteroposteriorly with flexion to 110 degrees. Laterally, the femoral condyle is composed entirely, or almost entirely, of a single circular facet similar in radius and arc to the posterior medial facet. The tibia is roughly flat. The femur tends to roll backwards with flexion. The combination during flexion of no anteroposterior movement medially (i.e., sliding) and backward rolling (combined with sliding) laterally equates to internal rotation of the tibia around a medial axis with flexion. About 5 degrees of this rotation may be obligatory from 0 degrees to 10 degrees flexion; thereafter little rotation occurs to at least 45 degrees. Total rotation at 110 degrees is about 20 degrees, most if not all of which can be suppressed by applying external rotation to the tibia at 90 degrees.

Adult↗