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Management of congenital pseudarthrosis of the tibia in children under 3 years of age: effect of early surgery on union of the pseudarthrosis and growth of the limb.

The study was undertaken to determine whether the results of treatment of pseudarthrosis of the tibia in children under age 3 are so poor as to recommend that surgery be deferred until after 3 years of age. Radiographs and case records of 26 consecutive patients with Crawford type IV congenital pseudarthrosis of the tibia who were treated operatively were reviewed. Growth abnormalities of the tibia, fibula, and femur of the affected limb at presentation were identified. The outcome of treatment, in terms of union of the pseudarthrosis, refracture rate, and limb length, in 13 children treated operatively before age 3 years was compared with those operated on later. Union of the pseudarthrosis occurred in 12 of 13 children (92%) who were treated before 3 years of age by excision of the pseudarthrosis, intramedullary rodding, and dual-onlay cortical bone grafting. Union occurred in only five of seven children who underwent the same procedure between the ages of 3 and 12 years. The extent of shortening of the limb at the time of surgery was least in children younger than 3 years. The limb length discrepancy remained virtually static in 11 children who had transarticular Rush rodding before age 3. Growth abnormalities of the fibula, tibia, and femur were less pronounced in children operated on early. The study suggests that there is no need to defer surgery for pseudarthrosis of the tibia until the child is older than 3 years.

Child↗

Regeneration of segmental diaphyseal defects in sheep tibiae using resorbable polymeric membranes: a preliminary study.

OBJECTIVE: To investigate whether a long bone cortex of well-defined thickness can be regenerated by using an anatomically designed membranous resorbable "tube-in-tube" implant and to establish the functions of membranes in the healing of segmental diaphyseal bone defects larger than the "critical size." DESIGN: Bone healing in segmental diaphyseal defects larger than the critical size in the sheep tibiae covered with a single porous tubular membrane or implanted with anatomically shaped porous double tube-in-tube membranes was evaluated. Membranes with different pore structures were applied alone and/or in combination with autogenous bone graft. BACKGROUND: Healing of segmental diaphyseal bone defects in animals can be enhanced by covering the defects with resorbable polylactide membranes. Based on the results of bone healing in defects ten millimeters long in the rabbit radii, it was suggested that the membrane prevents muscle and soft tissue from invading the defect and maintains osteogenic cells and osteogenic substances within the space covered with membrane, thus promoting new bone formation. The functions of membranes may differ, however, depending on the size and the location of the defect and on the experimental species used. Bone defects larger than the critical size may not heal at all, even if membranes are used. The critical-size defect is defined as the smallest bone defect that does not heal spontaneously when covered with polymeric membranes. To heal such defects, it is mandatory that membranes are used in combination with autogenic bone graft and/or a suitable bone substitute. If bone graft is used to fill the defect, the structure and geometry of the covering membrane will determine whether the graft will be vascularized and/or nourished from the surrounding soft tissue and, in consequence, survive. It can be appreciated that bone healing in areas of good vascularity should be more efficient than bone healing in poorly vascularized areas. The influence of all these factors on healing of bone in segmental diaphyseal defects covered with membranes is not known. METHODS: Four-centimeter-long diaphyseal segmental defects in the tibiae of six- to seven-year-old Swiss mountain sheep were covered with resorbable membranes from poly(LDL-lactide). In Group 1, a single microporous external membrane was used. In Group 2, one microporous membrane was inserted into the medullary cavity at the cut ends of the tibiae (internal membrane), and the other microporous membrane was placed on the outer surface of the cortex (external membrane). In Group 3, a single microporous external membrane was also laser-perforated to produce openings with a diameter in the range of 800 to 900 micrometers. In Group 4, the defect was filled with autogenous cancellous bone graft and covered with a single perforated membrane. In Group 5, one perforated internal membrane was inserted into the medullary cavity at the cut ends of the tibiae, and the other perforated membrane was placed on the outer surface of the cortex. Group 6 was identical to Group 5, except that cancellous bone graft was placed in the space between these two membranes. RESULTS: There was no bone healing in Groups 1, 2, 3, and 5. Only in Groups 4 and 6 did the defects heal. In Group 4, new bone was dispersed across the "medullary canal" formed by the membrane. In Group 6, the new bone had grown into the space between the outer and inner membranes, forming the "neocortex." CONCLUSIONS: The resorbable polymeric implant consisting of two concentric perforated membranes (the tube-in-tube implant) used in combination with cancellous bone graft to treat segmental diaphyseal defects in sheep tibiae allows for the reconstitution of the "neocortex" with well-defined thickness. (ABSTRACT TRUNCATED)

Absorbable Implants↗

A mobile-bearing knee prosthesis can reduce strain at the proximal tibia.

Mobile and fixed-bearing knee prostheses are likely to generate distinct strain gradients in the proximal tibia. The resulting strain distribution in the proximal tibia governs bone remodeling and affects implant integration and stability. We determined the effects of fixed and mobile-bearing total knee prostheses on strain distribution at the proximal tibia. This mobile-bearing prosthesis was evaluated in cadaveric specimens under axial and torsional loading. Strain on the proximal tibial cortex was measured with rosette strain gages and an optical full-field strain acquisition system. Tibial torsion in response to combined axial and torsional loading was documented. There was no difference in cortex strain between the fixed and the mobile-bearing prostheses under 1.5 kN axial loading. Superimposing 10 degrees tibial internal rotation induced 22% less compressive strain in the mobile-bearing prosthesis compared with the fixed-bearing prosthesis. Under 10 degrees tibial external rotation, the mobile-bearing prosthesis induced 33% less compressive strain than the fixed-bearing prosthesis. Optically acquired strain fields showed peak compressive strain at the anteromedial aspect 30 mm below the joint line. The mobile-bearing prosthesis reduced torque in the proximal tibia during knee rotation by 68-73% compared with the fixed-bearing prosthesis. Our data suggest that the particular mobile-bearing prosthesis tested potentially reduces elevated strain levels in the proximal tibia.

Aged↗

Residual deformities following successful initial bone union in congenital pseudoarthrosis of the tibia.

The pathology of congenital pseudoarthrosis of tibia is an enigma and the treatment is challenging. Despite achieving union of the pseudoarthrosis, these patients may have compromised function secondary to residual deformities. The purpose of this study is to analyze the prevalence of these deformities, the morbidity caused by them, and the methods to overcome the problems. Sixteen patients who had a successful union were retrospectively reviewed. Clinically, the following parameters were assessed: pain, joint stiffness, and limb length discrepancy (LLD). Anteroposterior and lateral lower extremity radiographs were performed to analyze (1) union of the tibia and fibula, (2) deformity of the tibia, (3) degree of ankle valgus, (4) degree of calcaneus of the os calcis, (5) LLD, and (4) refracture. The average follow-up was 16 years from the first and 8 years from the last surgical procedure. Residual deformities included valgus of tibia (average 11.4 degrees) and procurvatum (average 19.4 degrees) deformities of the tibia or valgus deformity of the ankle (average 21.3 degrees) and calcaneus of the os calcis (average 46 degrees). There were 9 refractures in 8 patients. Nine patients had an LLD (average 3.5 cm). The study demonstrates that careful follow-up of these patients is necessary and residual problems are to be treated as they occur.

Child↗

Tibia vara: results of hemiepiphyseodesis.

Tibia vara is a condition characterized by progressive deformity of the proximal tibia resulting in varus malalignment of the lower extremity. An alternative treatment strategy involving lateral hemiepiphyseodesis of the proximal tibia in the skeletally immature has been utilized at our institution for the last 10 years. The study group consisted of 23 patients (16 male, seven female) with 33 involved extremities. The median age at surgery was 11.8 years (range, 7.0-17.3). The median follow-up was 3.1 years (range, 0.8-6.2). Of the patients, 82.6% had a weight greater than the 95th percentile. The preoperative mechanical axis had a median value of 18.0 degrees (range, 5.0-31.0) and at the most recent follow up, a median value of 7.0 degrees (range, -12.0 to 46.0). In 18 (54.5%) extremities, the mechanical axis improved by more than 5 degrees . There was no progression of the overall deformity in 11 (33.3%) extremities. Four (12.1%) extremities had worsening of the deformity. At the time of latest follow up, nine (27.2%) extremities had required corrective osteotomy. Twenty-four (72.7%) were skeletally mature and had not required any further treatment. Goals of hemiepiphyseodesis in adolescent tibia vara or late sequelae of infantile tibia vara include (1) correction of deformity to avoid need for osteotomy, and (2) prevention of progression of the deformity to facilitate subsequent surgery. In this series of patients, 87.8% had either improvement or stabilization of the degree of their deformity.

Adolescent↗

A three-dimensional finite element analysis of the upper tibia.

A three-dimensional finite element model of the proximal tibia has been developed to provide a base line for further modeling of prosthetic resurfaced tibiae. The geometry for the model was developed by digitizing coronal and transverse sections made with the milling machine, from one fresh tibia of average size. The load is equally distributed between the medial and lateral compartments over contact areas that were reported in the literature. An indentation test has been used to measure the stiffness and the ultimate strength of cancellous bone in four cadaver tibiae. These values provided the statistical basis for characterising the inhomogeneous distribution of the cancellous bone properties in the proximal tibia. All materials in the model were assumed to be linearly elastic and isotropic. Mechanical properties for the cortical bone and cartilage have been taken from the literature. Results have been compared with strain gage tests and with a two-dimensional axisymmetric finite element model both from the literature. Qualitative comparison between trabecular alignment, and the direction of the principal compressive stresses in the cancellous bone, showed a good relationship. Maximum stresses in the cancellous bone and cortical bone, under a load which occurs near stance phase during normal gait, show safety factors of approximately eight and twelve, respectively. The load sharing between the cancellous bone and the cortical bone has been plotted for the first 40 mm distally from the tibial eminence.

Aged↗

Sectorial angioarchitecture of the human tibia.

The blood supply of the periosteum of the human tibia was investigated by anatomical dissection of 12 lower extremities which were filled with injection mass. By division of the tibia into 4 segments (proximal and distal fifths; proximal and distal diaphysis) a general supplying system of the periosteum was found. The proximal fifth of the tibial periosteum is nourished by branches of the arteriae recurrentes tibiales anterior et posterior and the aa. inferiores medialis et lateralis genus. At the proximal diaphysis (next three tenths of the tibia) periosteal branches arise from the aa. tibialis anterior and posterior, whereas the distal diaphysis is nourished exclusively by semicircular vessels of the a. tibialis anterior which twine around the bone and merge with each other at the facies medialis. Concerning the periosteal blood supply of the distal fifth of the tibia, two different types were found. In two thirds of the cases the lateral side was nourished by branches of the a. tibialis anterior, which are supported by vessels from the a. fibularis. In one third the latter branch was absent so that the rami periostales arising from the a. tibialis anterior nourished the lateral aspect of the distal tibia alone. The dorsal region was supplied in all cases by rami of the a. fibularis and a. tibialis posterior. On the medial side the periosteal nourishment is ensured only by anastomosis. Branches of the a. tibialis anterior supply the facies lateralis and facies posterior where it is supported by vessels of the a. tibialis posterior and in a minor region of rami of the a. fibularis (distal) and a. poplitea (proximal).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Gravity reduces the tibia when using a tibial guide that targets the intercondylar roof.

BACKGROUND: Reduction of the tibia relative to the femur with the knee in maximum extension is required to correctly position the tibial tunnel in the sagittal plane when using a guide that targets the intercondylar roof. The authors found no studies that determined (1) whether gravity reduces the tibia and (2) whether roof impingement is prevented without a roofplasty and without positioning the tibial tunnel too posteriorly. METHODS: The position of the tibia relative to the femur was measured from a lateral radiograph of the treated knee in maximum extension with and without the tibial guide and of the contralateral normal knee in extension in single-leg stance (control). RESULTS: The position of the tibia with and without the tibial guide was not different (P = .33, not significant) and was only 0.7 mm more posterior than the control knee (P = .0075). A roofplasty was not required, and the clearance was 2 mm or less. CONCLUSION: Gravity reduces the tibia on the femur when using a guide that targets the intercondylar roof. The use of a tibial guide that targets the intercondylar roof prevents roof impingement without a roofplasty and without positioning the tibial tunnel too posteriorly.

Adolescent↗

Anterior-posterior and rotational displacement of the tibia elicited by quadriceps contraction.

The anterior-posterior displacement and rotation of the tibia elicited by isolated loading of the quadriceps muscle was determined as a function of joint angle and muscle load using a computerized radiographic technique. Data collected from 12 fresh-frozen cadaveric knees demonstrated that quadriceps contraction can result in significant (less than 7 mm) anterior displacement of the tibia in the range of 0 degrees to 80 degrees of flexion, and a mild (less than 2 mm) posterior displacement in the range of 80 degrees to 120 degrees of flexion. Peak anterior displacement of 6.3 mm was observed at 30 degrees of flexion under a 12 kg load in the quadriceps, while a constant 1.5 mm posterior displacement was observed throughout flexion angles exceeding 80 degrees. It was further shown that the magnitude of the anterior displacement increased nonlinearly as the quadriceps force increased. Loading of the quadriceps also resulted in internal rotation of the tibia in the range of 0 degrees to 90 degrees of flexion, and in external rotation of the tibia in the range of 90 degrees to 120 degrees. Peak internal rotation of 7 degrees was observed at 15 degrees of flexion and a peak external rotation of 1 degrees was detected at 120 degrees of flexion. Larger quadriceps load resulted in larger rotation. We concluded that quadriceps contraction during knee extension has direct impact on anterior displacement and rotation of the tibia and therefore on anterior cruciate ligament stress, increasing it as the muscle's force is increased during knee extension.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Cruciate Ligament↗

Geometrical properties of the ovine tibia: a suitable animal model to study the pin-bone interface in fracture fixation?

To determine whether dimensional scaling (relative to the human) is necessary for screwed pins used in externally applied fracture fixation studies on sheep, geometrical data were determined for six ovine tibiae. Each tibia was potted relative to a lengthwise reference axis and sectioned at 5 per cent length intervals over its central 80 per cent. Enlarged (280 per cent) images of each cross-section were digitized at 1 mm increments around the periphery of the periosteal and endosteal surfaces, the data were digitally filtered, and geometrical properties were computed to include cross-sectional area A, maximum and minimum second moments of area (Imax and Imin), polar second moment of area J, and effective polar second moment of area J(eff). Proportional scaling of geometrical properties with respect to bone length (L2 for A, and L4 for second moments of area) significantly (p < 0.000001) decreased the coefficient of variation in data by an average 36 per cent. From 30-90 per cent distal, J(eff) for the ovine tibia is smaller but within 7 per cent of J--in stark contrast with the human tibia, where J(eff) has been reported as 70-80 per cent of J over the same tibial length. While previous ovine studies involving external fixator pins have employed the same diameter of pin as has been used in humans (that is 5 or 6 mm), a 'first-order' approximation of the data for A, Imax, Imin and J(eff) suggests these pins should be scaled down to 4 mm and 4.75 mm respectively for use on the ovine tibia over the range 25-80 per cent distal along its length.

Adult↗

Standardized bending and breaking test for the normal and osteoporotic metaphyseal tibias of the rat: effect of estradiol, testosterone, and raloxifene.

UNLABELLED: The fracture of bone plays a key role in osteoporosis. BMD measurement, however, is only an indirect parameter of this phenomenon. We therefore developed a highly sensitive three-point bending test for the metaphyseal tibias in rats to evaluate stiffness and strength. This was validated in a right-left comparison and a bioassay with soy-free food, estradiol, raloxifene, and testosterone in orchidectomized rats. INTRODUCTION: Osteoporosis becomes manifest predominantly in the metaphyseal rat tibia. The anti-osteoporotic character of substances should, therefore, be tested (mechanically) in this bone area. MATERIALS AND METHODS: We evaluated a new three-point bending test for the metaphyseal tibia in rats in a right-left trial. In an animal experiment, we studied the change of bone quality under estradiol (E)-, raloxifene (R)-, and testosterone (T)-supplemented food and compared it with trabecular BMD (qCT). RESULTS: In the right-left comparison, the mean difference between the metaphyseal loads of both tibias in 37 rats was 8.43% for the maximum load (Fmax) and 6.46% for the failure load (fL). These results show the high reproducibility of the test, because they are close to the usual intraindividual difference of the two extremities. In a second experiment, four groups of 11 3-month-old male orchidectomized rats were fed with soy-free food only (C) or with the additives E, T, or R for 12 weeks. E and R were similar for Fmax and fL. There were significant differences in the stiffness (E = 406.92 N/mm versus R = 332.08 N/mm), the yield load (yL; E = 99.17 N versus R = 83.33 N), and the ratio between yL and Fmax (E = 86.33% versus R = 76.37%). T was similar to the controls concerning F(max), fL, and stiffness. There were significant differences in yL (T = 49.00N versus C = 39.5N) and the ratio between yL and Fmax (T = 64.28% versus C = 51.28%). CONCLUSIONS: Estradiol is superior to raloxifene concerning stiffness and yield load, and both are superior to testosterone. We conclude that the described three-point bending test for the metaphyseal tibia is a highly sensitive method to study hormones and substances with regard to their osteoprotective character. The precision and the low SD of the presented results are superior to the data from qCT and the calculated index of stiffness (SSI).

Androgens↗

Thyroid hormones promote chondrocyte differentiation in mouse ATDC5 cells and stimulate endochondral ossification in fetal mouse tibias through iodothyronine deiodinases in the growth plate.

Thyroid hormones (THs), 3,3',5-triiodo-L-thyronine (T3) and L-thyroxine (T4), are important for the normal development of the growth plate (GP); congenital TH deficiency leads to severe dwarfism. In mouse chondrogenic cell line, ATDC5, T3 enhanced differentiation and increased Alizarin red staining, but did not affect Alcian blue staining. In organ-cultured mouse tibias, THs stimulated the cartilage growth, especially in the hypertrophic zone. Interestingly, T4 was as equally potent as T3 in organ-cultured tibias, which suggests that T4 is metabolized locally to T3, because T4 is a prohormone and must be converted to T3 for its activity. Two enzymes catalyze the conversion; type I deiodinase (D1) and type II deiodinase (D2). D1 has a ubiquitous distribution and D2, with a high affinity for T4, is present where the maintenance of intracellular T3 concentration is critical. Messenger RNAs (mRNAs) for D1 and D2 were detected in neonatal mouse tibias and ATDC5 cells. The enzyme activity was unaffected by the D1 inhibitor 6-propyl-2-thiouracil, suggesting that D2 mainly catalyzes the reaction. D2 mRNA was detected in differentiated ATDC5 cells. In organ-cultured mouse tibias, D2 activity was greater at later stages. In contrast, thyroid hormone receptors (TRs) were expressed in neonatal mouse tibias and ATDC5 cells, but their expression levels in ATDC5 cells were stable throughout the culture periods. Therefore, increased T3 production at later stages by D2 is likely to contribute to the preferential effects of THs in the terminal differentiation of GP. This article is the first to show that T4 is activated locally in GP and enhances the understanding of TH effects in GP.

Animals↗

The effects of low laser irradiation on angiogenesis in injured rat tibiae.

The influence of He-Ne laser radiation on the formation of new blood vessels in the bone marrow compartment of a regenerating area of the mid-cortical diaphysis of the tibiae of young adult rats was studied. A small hole was surgically made with a dentistry burr in the tibia and the injured area received a daily laser therapy over 7 or 14 days transcutaneously starting 24 h from surgery. Incident energy density dosages of 31.5 and 94.5 Jcm(-2) were applied during the period of the tibia wound healing investigated. Light microscopic examination of histological sections of the injured area and quantification of the newly-formed blood vessels were undertaken. Low-level energy treatment accelerated the deposition of bone matrix and histological characteristics compatible with an active recovery of the injured tissue. He-Ne laser therapy significantly increased the number of blood vessels after 7 days irradiation at an energy density of 94.5 Jcm(-2), but significantly decreased the number of vessels in the 14-day irradiated tibiae, independent of the dosage. These effects were attributed to laser treatment, since no significant increase in blood vessel number was detected between 8 and 15 non-irradiated control tibiae. Molecular mechanisms involved in low-level laser therapy of angiogenesis in post-traumatic bone regeneration needs further investigation.

Animals↗

Histological evaluation, in rabbit tibiae, of osseointegration of mini-implants in sites prepared with Er:YAG laser versus sites prepared with traditional burs.

OBJECTIVE: The aim of this study was to evaluate the different bone reactions in rabbit tibiae after the insertion of mini-implants by using two different techniques of site preparation: the superpulsed Er:YAG laser (VPS system) versus the traditional technique with burs. METHODS: One mm wide and 2 mm long implant sites were made in the tibiae of 12 rabbits (8 for each tibia): the authors used an Er:YAG laser with a sapphire tip on a contra-angle hand piece with a 1.0 mm diameter in a VPS mode (with 200 mJ and 30 Hz) to make 4 bone sites and a calibrated traditional bur to drill the other 4 sites in each tibia. The authors inserted a threaded mini-implant, with a sandblasted and acid-etched surface, in the 2 laser implant sites and in the 2 drilled sites of each tibia. The other sites were used as controls. At 0, 7, 15, 30, 45, and 60 days from the surgery, 2 animals each were euthanized, and the retrieved specimens were evaluated. RESULTS: No implant was lost, and the osseointegration was comparable in all implant sites. Histologically, in the 7- and 15-day postoperative specimens, the laser sites showed some amorphous tissue caused by the carbonization of bone during the laser procedure. The sites without implants showed good regeneration of the bone: it was faster in the drill defects because in the laser ones there was some carbonized amorphous tissue. After 30 days postoperatively, the regeneration was the same in all sites. CONCLUSIONS: In comparison with the traditional drilling procedures, Er:YAG laser can be considered efficient in surgery of the bone without inducing irreversible damages, even if it is possible to observe the presence of some carbonized amorphous tissue in the early part of the healing process. This tissue is progressively resorbed in a way similar to a bone graft and doesn't impede the bone formation and osseointegration processes. Further clinical and histological studies are necessary to better define this amorphous tissue and an efficient and safe operative protocol in the surgery of bone with an Er:YAG laser.

Animals↗

Effects of implant thread geometry on percentage of osseointegration and resistance to reverse torque in the tibia of rabbits.

BACKGROUND: Dental implant thread geometry has been proposed as a potential factor affecting implant stability and the percentage of osseointegration. Therefore, the aim of this prospective, randomized, parallel arm study was to evaluate the effects of dental implant thread design on the quality and percent of osseointegration and resistance to reverse torque in the tibia of rabbits. METHODS: Seventy-two custom-made, screw-shaped, commercially pure titanium implants (3.25 mm diameter x 7 mm length) were placed in the tibiae of 12 white New Zealand rabbits. Each tibia received three implants of varying thread shapes: one with a V-shaped, one with a reverse buttress, and one with a square thread design. The rabbits were sacrificed following an uneventful healing period of 12 weeks. Implants in the right tibiae underwent histologic and histomorphometric assessments of the bone-to-implant contact (BIC) and the radiographic density of surrounding bone, while implants in the left tibiae were used for reverse-torque testing. Differences between the three thread designs were examined using analysis of variance (ANOVA). RESULTS: Data showed that the square thread design implants had significantly more BIC and greater reverse-torque measurements compared to the V-shaped and reverse buttress thread designs, while no differences were found in radiographic bone density assessments. CONCLUSION: These results indicate that the square thread design may be more effective for use in endosseous dental implant systems.

Analysis of Variance↗

Determination of sex from the tibia of adult Turkish cadavers.

The aim of this research is to determine sex from the tibia. The tibia is an ideal bone because it resists erosive forces and keeps its anatomical shape for a long time even after being buried. Additionally, we tried to obtain a higher discrimination rate by using the biarticular breadth that was accepted as the most valid criterion in previous sex discrimination studies which were directed to the proximal part of the tibia. Right and left tibiae from 55 randomly selected adult Turkish cadavers (25 to 68 years) were measured to the nearest millimeter performed with a caliper; a total of six dimensions, one from the proximal and five from the distal ends, was measured. Canonical discriminant function test was performed to develop formulae and assess the accuracy of the technique. The results indicated that classification accuracy ranged from 89% in the right and 87% in the left for biarticular breadth. There was a minimal difference between the sides and the height of the medial malleolus. In conclusion, the distal and proximal dimensions of the tibia are highly discriminative as the sexual dimorphs in this Turkish sample. The study compares well with those on blacks and whites of North America and South Africa.

Adult↗

The fibular incisura of the tibia with recurrent sprained ankle on magnetic resonance imaging.

OBJECTIVE: The aim of this study was to investigate the fibular incisura of the tibia in type I and II recurrent sprained ankle. METHODS: A total of 18 limbs (9 right, 9 left) were examined for the fibular incisura of the tibia by magnetic resonance imaging at Gunmar Magnetic Resonance Imaging Center between September 2000 to May 2001. This group consisted of 10 males and 8 females and their age ranged between 18-61 years. The control group was made up of 75 participating volunteers without previous history of trauma in the ankle. RESULTS: The measurements of the length of the anterior and posterior facets, depth of the fibular incisura of the tibia and the distance between anterior margin of the tibia and anterior margin of the fibula in the patient group were visibly different from the measurements of the control group. In recurrent sprained ankle, the anterior and posterior tubercles were lengthier, the depth of the fibular incisura of the tibia was deeper and the fibula was more anterior than the control group. The measurements of the angle between anterior and posterior facets and the vertical distance of tibiofibular overlapping in the patient group were slight different from the measurements of the control groups. CONCLUSION: These characteristics, which were observed in the recurrent sprained ankles, may be anatomically predisposed to recurrent ankle sprains.

Adult↗

[Finite element analysis of human tibia in vitro].

This investigation was aimed at the fatigue fracture of tibia that often occurs in soldiers, as well as in dancers and athletes. The data of ground reaction force(GRF) of soldiers were measured using a force platform in three common gaits: marching, parading and running. The stress distribution in tibia under these GRFs were analyzed with a FE model. The results showed that the smallest GRF(744.8N) is in quick marching, the next (1156.4N) in parading and the largest (1391.6N) in running. The stress distribution under GRF was mot uniform in the tibia. The maximum stresses occurred at a site 1/3 tibia length below the knee where tibia fracture is often seen clinically. The maximum stresses were 110 MPa and 115 MPa in parading and running respectively. This means that the tibial tractures in soldiers are mostly associated with stress, i.e. the greater the stress is, the higher the incidence of stress fracture comes about.

Adult↗