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PubMed2004

A combined RSA and FE study of the implanted proximal tibia: correlation of the post-operative mechanical environment with implant migration.

There is strong evidence to suggest that inducible displacements, migration and implant loosening are closely related to the initial mechanical environment of the implanted tibia. If this is true, then it should be possible to predict the likelihood of implant migration using patient-specific finite element models. Finite element models of the proximal implanted tibiae were analysed based on pre-operative quantitative computed tomography data of four patients entered into a radiographic migration study. These four patients were also part of an radiostereometric analysis (RSA) study. A variety of load cases were analysed and the risk of bone failure determined for a 2 mm layer of bone immediately beneath the tibial tray. The results were compared with the RSA data measured 1 year post-operatively for each patient. For each patient, an appropriate load case was selected based on patient weight and on the varus-valgus migrations observed in the migration study. The two patients with press-fit implants were predicted to have the highest risk of failure and were found to migrate the most. The two patients with bonded implants (one HA coated and one cemented) were found to have a low risk of failure and these implants migrated the least. This study suggests that the degree of implant migration is dependent on the initial mechanical environment and can be determined using patient-specific finite element analysis.

Aged↗

PubMed2005

Vascular changes in the periosteum of congenital pseudarthrosis of the tibia.

The etiology and the pathogenesis of congenital pseudarthrosis of the tibia (CPT) are still unknown. The affected tibia exhibits insufficient mechanical strength and osteogenetic capability. CPT is frequently associated with neurofibromatosis type 1 (NF1; von Recklinghausen's disease); however, both diseases have not yet been linked pathogenetically. This study presents the pathomorphologic findings of CPT under special consideration of NF1. Therefore, samples from patients operated on for CPT (n = 4) with (n = 3) and without (n = 1) neurofibromatosis were investigated by light microscopy, immunohistochemistry, and electron microscopy. The most striking finding in all patients was thickened periosteum with accumulation of nerval cells surrounding small arteries, causing subtotal or complete obliteration. In conclusion, impaired vascularization can result in decreased osteogenic capabilities. The similarity of ultrastructural findings in the abnormal periosteum and in skin neurofibromas of neurofibromatosis patients may indicate a pathogenetic association of both diseases.

Adolescent↗

PubMed1992

Longitudinal stress fracture of the tibia: two cases.

Stress fracture of the tibia occurs in individuals who subject their extremities to repeated trauma. They can arise in otherwise healthy bone that is subjected to excessive loads (as in the marathon runner) or in abnormal bone that is subjected to minor loads (as in osteoporosis). These fractures may be anywhere along the tibial shaft and tend to be either transverse or oblique in orientation. We report two cases of stress fracture that ran longitudinally in the distal one third of the tibia. Both patients were healthy and did not describe excessive physical activity prior to fracture. Both describe a repetitive twisting action prior to fracture. Computed tomography was diagnostic in both cases following abnormal bone scans and normal plain radiographs. This unusual pattern of fracture has been reported on only four occasions in five patients in the literature.

Adult↗

PubMed2000

Strain distribution in plated and unplated sheep tibia an in vivo experiment.

After plate osteosynthesis changes in bone biology and bone mechanics are observed in the plated bone segment. Compromise of the vascular supply in the plate bed leads to a remodelling process and to a temporary porosity in the bone cortex underneath the plate. In addition, the plate takes over some of the physiological loading of the bone, which in turn alters the normal strain distribution of the cortical bone tissue. The aim of the present study is to determine the tissue deformation of the sheep tibia in vivo and the changes in tissue strain due to plating with plates of different rigidities. Measurements were performed on the intact bone at the mid diaphysis using the strain gauge technique. With different connections on the tension bridge (Wheatstone bridge), the strain was measured separately for pure axial loading, bending, and torsion before and after plating with a 4.5 mm stainless steel or titanium DCP. Under physiological load the sheep tibia is mainly deformed in torsion (62%) and bending (33%), and much less in axial loading (5%). Plating with a steel plate reduces the overall tissue strain by 18%, with a titanium plate by 13%. This reduction is mainly due to a reduction in axial tissue strain due to axial loading and bending and less to the reduction of tissue strain under torsion. In our in vivo model, plating with steel or titanium plates leads to a reduction of the physiological tissue strains. The difference between the different plates is small due to the fact that the high tissue strain under torsion is only slightly affected by plating. Thus, from the purely mechanical point of view and with regard to preserving normal tissue strains as much as possible, titanium plates offer little advantage compared with stainless steel plates. But, titanium as an implant material may offer advantages with respect to tissue compatibility and infection resistance.

Animals↗

PubMed2003

Trabecular bone strain changes associated with subchondral stiffening of the proximal tibia.

Subchondral stiffening is a hallmark pathologic feature of osteoarthritis but its mechanical and temporal relationship to the initiation or the progression of osteoarthritis is not established. The mechanical effect of subchondral stiffening on the surrounding trabecular bone is poorly understood. This study employs a relatively new application of digital image correlation to measure strain in the trabecular region of the proximal medial tibia in normal specimens and in specimens with simulated subchondral bone stiffening. Coronal sections from eight normal human cadaveric proximal tibiae were loaded in static compression and high resolution contact radiographs were made. Repeat contact radiographs were collected after the subchondral bone near the jointline was stiffened using polymethylmethacrylate. Digital images, made from loaded and unloaded contact radiographs, were compared using in-house software to measure trabecular displacement and calculate trabecular bone strain. Overall strain was higher in the stiffened specimens suggesting experimental artifiact significantly affected our results. Consistent increases in median maximum shear strain, median maximum principal strain, median minimum principal strain, and peak shear strain were measured near the inner and outer edges of the stiffened segment. Our experiment provides direct experimental measurement of increases in trabecular bone strain caused by subchondral stiffening, however, the clinical and biologic importance of strain increases is unknown.

Aged↗

PubMed1992

Tibia vara: a complication of adolescent obesity.

Tibia vara is characterized by inhibited growth of the medial portion of the proximal tibial growth plate, leading to progressive bowleg deformity. Twenty-nine adolescent patients with this condition were reviewed: all were black, 27 (93%) were male, and 19 (66%) had only one side affected. Progressive deformity rather than knee discomfort was the most common presenting complaint. The deformity reportedly developed rapidly during the adolescent growth spurt. The body weights of these patients exceeded the 95th percentile for age and gender by an average of 43 kg. The absence of significant symptoms and a body habitus that obscured the deformity often resulted in delayed diagnosis. Physicians involved in the care of obese black male adolescents should carefully examine them for tibia vara, which has a reported prevalence of 2% to 3% in this population. Treatment options are severely restricted if the condition is not diagnosed early.

Adolescent↗

PubMedDate not supplied

Tetracycline derivatives inhibit cartilage degradation in cultured embryonic chick tibiae.

Tetracyclines have been used extensively as antibiotics and growth promoters in the poultry industry. However, they can inhibit angiogenesis and matrix degradation, both of which are essential for normal growth plate cartilage development. The purpose of this research was to test the ability of several tetracyclines to inhibit cartilage degradation in cultured embryonic chick tibiae. Based on gross observations and biochemical quantitation of collagen release into the media, minocycline, doxycycline, oxytetracycline, and tetracycline inhibited cartilage degradation at 20, 40, 60, and 80 micrograms ml-1 respectively. Chlortetracycline did not inhibit cartilage degradation at concentrations tested. The ability of the tetracycline derivative to inhibit cartilage degradation was in general related to its hydrophobicity. Since a majority of the cartilage in the embryonic chick tibia will develop into the post hatched growth plate, it may be important to determine if any of the tetracyclines used as antibiotics could cause problems in in vivo growth plate cartilage development.

Animals↗

PubMed2003

The removal torque of titanium screw inserted in rabbit tibia treated by dual acid etching.

Chemical acid etching alone of the titanium implant surface have the potential to greatly enhance osseointegration without adding particulate matter (e.g. TPS or hydroxyapatite) or embedding surface contaminants (e.g. grit particles). The aims of the present study were to evaluate any differences between the machined and dual acid etching implants with the removal torque as well as topographic analysis. A total of 40 custom-made, screw-shaped, commercially pure titanium implants with length of 5 mm and an outer diameter of 3.75 mm were divided into 4 groups, 10 screws in each, and chemical modification of the titanium implant surfaces were achieved using HF and HCl/H(2)SO(4) dual acid etching. The first exposure was to hydrofluoric acid and the second was to a combination of hydrochloric acid and sulfuric acid. The tibia metaphysics was exposed by incisions through the skin, fascia, and periosteum. One implant of each group was inserted in every rabbit, 2 in each proximal tibia metaphysics. Every rabbit received 3 implants with acid etched surfaces and 1 implant with a machined surface. Twelve weeks post-surgically, 7 rabbits were sacrificed, Subsequently, the leg was stabilized and the implant was removed under reverse torque rotation with a digital torque gauge (Mark-10 Corporation, USA) (Fig. 1). Twelve weeks after implant placement, the removal torque mean values were the dual acid etched implants (24%HF+HCl/H(2)SO(4), group C) required a higher average force (34.7 Ncm), than the machined surface implants (group A) (p=0.045) (Mann-Whiteney test). Scanning electron micrographs of acid etching of the titanium surface created an even distribution of very small (1-2 microm) peaks and valleys, while machining of the titanium surface created typical microscopically grooved surface characteristics. Nonetheless, there was no difference in surface topography between each acid etched implant groups. Therefore, chemically acid etching implant surfaces have higher strengths of osseointegration than machined implant surfaces. There is less correlation between removal torque and the difference in HF volume%.

Acids↗

PubMed2003

A removal torque of the laser-treated titanium implants in rabbit tibia.

The purpose of the present study is to evaluate the significance of different surface textures by comparison of the removal forces for laser-treated and machined titanium screw 8 weeks after the installation in rabbit tibia. A total of 14 screw shaped, commercially pure titanium implants with a length of 5 mm, a diameter of 3.75 mm were grouped as follows: Group A: seven implants left as-machined; Group B: seven implants treated with laser method (CSM implant, CSM company, Daegu, Korea) Topographic evaluation was performed with scanning electron microscope (Hitachi S-4200, Japan) to compare the surface structure of laser-treated and machined ones. Installation procedures were done according to Branemark protocol after pre-threading, machined implants were inserted in right tibia metaphysics and laser-treated surface implants were inserted in left ones. Eight weeks post surgically seven rabbits were sacrificed. The implant sites were exposed, and the bone and soft tissues that had formed on top of the implants were carefully removed. Subsequently, the force needed to unscrew the implants (n=14) was measured using a digital torque gauge (Mark-10 corporation, USA). Scanning electron micrographs of the laser-treated and machined control groups demonstrated created a deep and regular honey-comb pattern with small pore, while machined treatment created the typical microscopically grooved and relatively smooth surface characteristic. Eight weeks after implant placement, the average removal torque was 23.58+/-3.71 N cm for the machined implants, 62.57+/-10.44 N cm for the laser-treated implants. The torque measurements yielded statistically significant differences between the machined group and the laser-etched group (p=0.00055) (Wilcoxon's signed-rank test). The laser-treated group achieved higher removal torque values compared to the machined control group.

Animals↗

PubMed1998

Pseudotumor formation in tibia in Gaucher's disease.

A very rare case of type 1 Gaucher's disease with pseudotumor formation in the right tibia is presented. In addition to the characteristic radiographic finding of distal femoral flaring (Erlenmeyer flask deformity), a lobulated osteolytic area with surrounding sclerosis was seen in the proximal metaphysis of the right tibia. Adjacent to this pseudotumor appearance was an old pathologic fracture and no significant soft tissue swelling was evident, both of these features being reported for the first time in association with Gaucher's disease.

Adolescent↗

PubMed1997

Arthroscopic reduction and fixation of bony avulsion of the posterior cruciate ligament of the tibia.

Bony avulsion fractures of the posterior cruciate ligament of the tibia have commonly been treated by open reduction and internal fixation using the posterior approach. However, this approach, using the prone position, makes it difficult to investigate and treat other combined injuries of the knee joint. We report a case of posterior cruciate ligament avulsion of the tibia that was arthroscopically reduced and firmly fixed with two cannulated screws. The posterior sag was absent after the operation and the result was excellent. By arthroscopy, we got rigid fixation of the avulsed fragment for early rehabilitation, and detection of a concomitant injury was also possible.

Arthroscopy↗

PubMed1988

Distribution of bone strength in the proximal tibia.

Indentation tests were used to determine the ultimate strength of the proximal tibia. Measurements were made at the subchondral bone surface and on transverse planes up to 25 mm below the surface. Medial condyles were stronger than lateral condyles, and in both cases bone strength decreased abruptly with distance from the surface, especially over the first 5 mm. The mean bone strength was greater in men than in women in both condyles, especially in the harder upper layers. The areas of greatest strength on both the medial and lateral sides varied with depth. At the surface, maximum strength in the medial region was more posterior in men than in women. With increasing depth, the area shifted medially in the medial region and laterally in the lateral region. Spatial distribution of strength across planes of the tibia seems consistent with anticipated patterns of load distribution in weight bearing and with the contiguity of the trabecular bone. The data are relevant to an understanding of normal joint mechanics and to the design and placement of prostheses in total knee arthroplasty.

Aged↗

PubMed1999

Discrepancy in the length of the tibiae in unilateral congenital dislocation of the hip.

We measured discrepancy in the length of the tibiae in cases of unilateral congenital dislocation of the hip (CDH) in 10 patients. The mean shortening of the tibia on the affected side was 1 cm and was not related to the severity of the dislocation. Patients who are about to undergo total hip arthroplasty for CDH should be warned that the operation is unlikely to restore normal leg length.

Adult↗

PubMed2002

Histological findings of bone remodeling around smooth dental titanium implants inserted in rabbit's tibias.

Nowadays, there are many kinds of implants with different covering layers. The aim of these wide spectra is to discover the material that has the best possible biocompatibility. The presence of so many kinds of covering layers indicates that this aim has not been reached until now. The implant anchorage in the bone is very important for the stability of the element that has to support much pressure when under use. As it is known, the implant/bone interface does not present the ideal result expected by all professionals. In the laboratory there are possibilities of researching many kinds of implants--under different techniques of insertion. This will lead to the best methods and materials available. Titanium is the basic material used by many authors and needs no further discussion. So far it is the material with the best biocompatibility. The aim of this work is to observe and study the bone healing in the interface between a titanium implant and bone under light microscopic technique. Commercial pure titanium implants with a smooth surface were inserted in rabbit's tibias where they remained for eight weeks. The amount of bone inside the implant threads was quantified by the use of a stereologic method. The histological results indicated that an intense remodeling process of the cortical bone was found close to the implant surface and in the stereometry a higher amount of the new bone formation was also observed in the cortical tibia at the implant/bone interface.

Animals↗

PubMed2004

Bone remodeling analysis of various dental implant surfaces using polyfluorochrome sequential labeling in rabbit tibias.

The purpose of this study is to analyze the bone remodeling process after the placement of threaded implants with rough (RBM) and hydroxyapatite coated surfaces (HA) in rabbit tibias using polyfluorochrome sequential labeling. Histomorphometry was performed in order to quantify the amount of each label deposited during the healing period. This work demonstrates the possibility of periodic identification of apatite deposition during bone remodeling around titanium and ceramic implants. It has been concluded that the polyfluorochrome sequential labeling is an important tool for identification of bone remodeling after the insertion of titanium and ceramic implants inside rabbit tibias.

Animals↗

PubMed1997

Application of automatic image segmentation to tibiae and vertebrae from ovariectomized rats.

Automatic contextual segmentation algorithms were developed to objectively identify bone compartments in pQCT images of tibiae, femora, and vertebrae. Principal advantages of this approach over existing techniques such as histomorphometry are as follows: (a) the algorithms can be implemented in a fast, uniform, nonsubjective manner across many images, allowing unbiased comparisons of therapeutic efficacy; (b) much larger volumes in the region of interest can be analyzed to derive true volumetric parameters for trabecular and cortical bone compartments; and (c) pQCT can be used to quantitate bone effects longitudinally in vivo. An automatic contextual segmentation algorithm was used to analyze over 600 scans of proximal tibiae, distal femora, and L-4 vertebrae from studies with ovariectomized rats. Accuracy and precision analyses were performed, and correlation to histomorphometry parameters showed that pQCT trabecular bone density correlates to Tb.N with r = 0.93, while BV/TV correlates to Tb.N with r = 0.95. In other words, pQCT correlates as well to histomorphometry as histomorphometry does to itself. We conclude that the developed automatic segmentation algorithm provides fast, precise, and objective quantitation of bone compartments that are highly correlated with histomorphometry measurements.

Absorptiometry, Photon↗

PubMed2000

Tibia metastasis without prostate specific antigen (PSA) increase following radical vesiculo-prostatectomy.

OBJECTIVES: PSA is regarded as the best method in the follow-up of prostate carcinoma. After radical vesiculo-prostatectomy the prostate carcinoma seldom recurs at zero or nearly zero PSA levels. METHODS: The authors have used PSA since 1989 and they have found only one case where metastasis in the tibia came without an increase in PSA levels. RESULTS: Tibia metastasis showed lower tissue activity of PSA than did the primary tumor in the prostate. The authors think this explains the zero PSA level when the metastasis developed. CONCLUSIONS: The authors think based on their case that PSA free progression prostate cacncers may cases where the metastases do not produce PSA.

Adenocarcinoma↗

PubMed1997

A novel spontaneous metastasis model of human osteosarcoma developed using orthotopic transplantation of intact tumor tissue into tibia of nude mice.

Evaluation of potential new treatment strategies requires adequate experimental tumor models which resemble the clinical situation as closely as possible. The purpose of the present study was to establish a new human osteosarcoma spontaneous metastasis model using orthotopic transplantation of histologically intact tumor tissue into the tibia of nude mice. Intact tumor pieces, obtained from the 32nd serial passage of subcutaneously growing human osteosarcoma xenografts, were implanted into the proximal tibia in 31 nude mice. Animals were sacrificed and autopsied 2, 4, 6, and 8 weeks after transplantation and examined macroscopically and microscopically for local tumor growth and metastases. All mice developed local intratibial bone tumors that were radiographically and histologically similar to primary human osteosarcoma. Lung metastases were observed in all mice, local and distant lymph node metastases in 15 (48%), and liver metastases in 6 (19%) mice. The microscopic appearance of the metastases was similar to that observed in the donor patient's tumor, corresponding subcutaneous xenografts and orthotopically transplanted intratibial tumors. This spontaneous metastasis model of human osteosarcoma in nude mice may resemble a clinical situation and could thus be useful for studies on local tumor growth, metastasis formation and therapy.

Animals↗