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PubMed2001

Surface analysis of Ti-15Zr-4Nb-4Ta alloy after implantation in rat tibia.

A new Ti-15Zr-4Nb4Ta alloy without V was implanted in rat tibiae for 6-48 weeks. The new bone formation surrounding the Ti implant in bone marrow, surface analysis of the Ti alloy after implantation, and metal concentrations in dried bone tissue containing new bone were investigated. New bone was well formed around the Ti-15Zr-4Nb-4Ta alloy implanted in bone marrow. The mean thickness of the new bone increased up to 24 weeks after implantation, and changes in the mean thickness thereafter, up to 48 weeks. were very small. The number of corrosion pits observed in the Ti-6Al-4V extra low interstitial (ELI) alloy surface tended to be slightly more than that of the Ti-5Zr-4Nb-4Ta alloy implant. The concentrations of metal elements in the bone tissue containing the new bone tended to increase slightly more than in bones without the implant.

Alloys↗

PubMed2002

Bone repair in radii and tibias of rabbits with phosphorylated chitosan reinforced calcium phosphate cements.

Biocompatibility of two calcium phosphate cements (CPCs), reinforced with phosphorylated chitosan (P-chitosan), was investigated in rabbits in present study. The two CPCs are monocalcium phosphate monohydrate (MPCM) with calcium oxide (CaO) in 1 M phosphate buffer (i.e. MCPM/CaO/1 M phosphate buffer cement, CPC-I) and dicalcium phosphate dihydrate (DCPD) with calcium hydroxide [Ca(OH)2] in 1 M Na2HPO4 solution (i.e. DCPD/Ca(OH)2/1 M Na2HPO4 cement, CPC-II). Different amount of P-chitosan was added to the liquid phase before the power phase was mixed with the liquid phase. The MCPM/CaO/1 M phosphate buffer/P-chitosan cements (P-CPC-I) with neutral pH were filled into the holey defects of rabbit tibias. While the DCPD/Ca(OH)2/1 M Na2HPO4/P-chitosan cements (P-CPC-II) shaped as prehardened cylinders were implanted into rabbit radial defects. After operation, the two serial groups and CPC-II controls were observed for 1, 4, 12 and 22 weeks, respectively. Histological and histomorphological studies proved that P-chitosan containing cements are biocompatible, bioabsorbable and osteoinductive. The biodegradation rate has a negative relationship with the P-chitosan content. Progressive substitution took place at the interface of implants and host bones. No adverse effects were found in tissues around the bone defects. Thus, they could be used as bone substitutes in clinic.

Animals↗

PubMed2003

Biomechanical and histomorphometric investigations on two morphologically differing titanium surfaces with and without fluorohydroxyapatite coating: an experimental study in sheep tibiae.

The influence of fluorohydroxyapatite (FHA) coating and surface roughness of Ti6Al4V implants on bone response was investigated. Uncoated and FHA-coated screws with lower (LR and LR+FHA; Ra: 5.7+/-0.2 microm) and higher (HR and HR+FHA; Ra: 21.8+/-0.9 microm) surface roughness, were inserted into the diaphyses of 8 sheep tibiae. Twelve weeks after implantation, extraction torque and bone-to-implant contact were evaluated. The smoothest surfaces showed an improved extraction torque and significant differences were observed between LR and HR (-24.6%, p<0.0005), LR and HR+FHA (-30.7%, p<0.0005), LR+FHA and HR (-17.4%, p<0.005), and LR+FHA and HR+FHA (-24.0%, p<0.005). The bone-to-implant contact data paralleled the biomechanical data: the smoother the surface, the greater the bone-to-implant contact. Significant (p<0.0005) decreases in bone-to-implant contact were observed between LR+FHA and HR (-24.2%), and between LR+FHA and HR+FHA (-29.2%). The current findings suggest that LR surfaces significantly improve the osteointegration rate of implanted cortical screws independently of the FHA coating.

Animals↗

PubMed1997

Histomorphometric analysis of the response of rat tibiae to shape memory alloy (nitinol).

The bone reaction to nitinol (Ni-Ti), a metal with shape memory, and other materials inserted transcortically and extending into the medullary canal of rat tibiae was quantitatively assessed using an image processing system. The materials examined were implants, all of the same shape and size, composed of nitinol, pure titanium (Ti), anodic oxidized Ti (AO-Ti), a titanium alloy (Ti-6Al-4V) and pure nickel (Ni). While the other four implant materials were progressively encapsulated with bone tissues, Ni was encapsulated with connective tissues through the 168-day experimental period, and the Ni implants showed no bone contact at any time during the experimental period. Histometric analysis revealed no significant difference among the tissue reactions to Ti, AO-Ti and Ti-6Al-4V, but Ni-Ti implants showed significantly (P < 0.01) lower percentage bone contact and bone contact area than any of the other titanium or titanium alloy materials.

Alloys↗

PubMed1997

Sex determination from the femur and tibia in South African whites.

With the current high incidence of violent crimes in South Africa, it has become very important to be able to determine the sex of individuals from their skeletal remains. The aim of this study is to provide standards usable for this purpose, to be used on the contemporary South African white population. Very little skeletal data is available for this group. Osteometric information was obtained from 56 male and 50 female individuals from cadaver collections. Six femoral and seven tibial measurements were taken, and subjected to SPSS discriminant function analysis. The distal breadths from both the femur and tibia provided the best discrimination. Formulae were developed for a number of combinations of measurements, which can be used to determine the sex on fragmentary remains. Average accuracies ranged from 86% to 91%, with female accuracies slightly higher than those of the males. The results of this study compares well with others, e.g., those from American whites.

Adult↗

PubMed2000

Sex determination by discriminant function analysis of the right tibia in the prehispanic population of the Canary Islands.

This study has been performed in order to define standards usable to determine the sex of prehispanic individuals from the Canary Islands from their skeletal remains. Osteometric information at the right tibia was obtained from 59 complete skeletons from Gran Canaria, housed in the Museo Canario (Las Palmas), 45 males and 14 females (this constitutes the totality of complete prehispanic skeletons known from Gran Canaria). The parameters measured were: tibial length, proximal and distal epiphyseal breadth, transverse and anteroposterior diameter, perimeter at the nutrition foramen levels and minimum shaft perimeter. These parameters were subjected to different SPSS discriminant function analysis, combining all of them, or only the proximal or distal ones, without tibial length, etc., in order to obtain functions usable even if only bone fragments are available. Transverse diameter, proximal epiphyseal breadth and minimum shaft perimeter showed the highest discriminant power. The functions obtained showed high average accuracies, ranging from 94.9 to 98.3%, with female accuracies of 100%. The functions obtained were further applied to a test prehispanic population (ten males and ten females) from El Hierro. Overall accuracies of the functions when applied to this population ranged from 65 to 94.7%, with female accuracies ranging 80% to 100%.

Atlantic Islands↗

PubMed1999

Effects of trabecular bone on marrow relaxation in the tibia.

The effects of bone on marrow relaxation in the trabecular volume of the most proximal 3 cm in the left tibia were studied with a RF-spoiled gradient echo MRI protocol on a 1.0 T MR unit. The MR measurements were performed on six healthy volunteers, and repeated within one month in order to assess the precision of the method. In the same subjects, the area bone mineral density (BMD, g/cm2) was measured at the left proximal femur using dual-energy X-ray absorptiometry. The calcaneus of the same side was examined with quantitative ultrasound. The marrow T2* relaxation deviated from a mono-exponential decay, and resembled the decay of subcutaneous fat. The shape of the relaxation curve reflected the presence of several spectral components in bone marrow, and was further influenced by the amount and structure of the surrounding trabecular bone. The bone marrow decays showed substantially reduced inter-subject variability after normalisation of the marrow data fit parameters to corresponding values for s.c. fat. This suggests the use of an internal adipose tissue reference in order to correct for diet-related variations of marrow T2* estimates. The mean relative precision of the MR measurements was between 5% and 10% depending on the data fit model. Moderate-to-strong correlations between DXA BMD indices in the proximal femur and MR parameters were found (r(max)=-0.96; p < 0.01), while ultrasound-derived measures of bone strength measured on the calcaneus demonstrated significantly weaker correlations to the MR parameters (r(max)=-0.78; p > 0.05). The method employed in this study showed reasonable precision and a moderate to good correlation compared to other bone parameters derived at the same extremity, and is a promising tool for the use on patients.

Absorptiometry, Photon↗

PubMed2003

Effects of locally applied vascular endothelial growth factor (VEGF) and VEGF-inhibitor to the rabbit tibia during distraction osteogenesis.

INTRODUCTION: Therapeutic angiogenesis, a novel concept in tissue engineering, is neo-formation of blood vessels in a tissue upon delivery of an angiogenic growth factor to the tissue. We hypothesised that therapeutic angiogenesis could enhance bone formation and challenged the hypothesis in an experimental model of distraction osteogenesis. METHODS: Rabbits, divided into three equal groups of 12, had their right tibia lengthened by distraction osteogenesis. A mini-osmotic pump delivered to the osteotomy gap either recombinant human vascular endothelial growth factor (VEGF), VEGF-inhibitor, or vehicle alone during the latency and distraction phase. After consolidation, we assessed bone blood flow by radioactive microsphere entrapment, measured torsional stiffness and bone mineral content, and did histomorphometry. RESULTS: VEGF and VEGF-inhibitor treatment failed to influence bone blood flow, torsional stiffness, bone mineral content and histomorphometric indices of the bone regenerate. However, VEGF treatment increased the blood flow in bone of the distracted limb and VEGF-inhibitor treatment decreased bone blood flow. CONCLUSION: The regenerate was unresponsive to VEGF and VEGF-inhibitor treatment in contrast to the neighbouring bone, which implies different biological properties of the vasculature in native and regenerating bone. VEGF is not recommended for enhancement of bone formation in this setting.

Angiogenesis Inducing Agents↗

PubMed1997

The effect of anterior cruciate ligament graft fixation site at the tibia on knee stability: evaluation using a robotic testing system.

Despite its current popularity and relative success, endoscopic reconstruction of the anterior cruciate ligament (ACL) using a bone-patellar tendon-bone (BPTB) graft has not yet been perfected. Using a recently developed robotic/UFS testing system, we assessed the overall stability of porcine knees following ACL reconstruction with different sites of tibial graft fixation--proximal, central, and distal. Testing of the intact knee was performed first to determine the normal anterior-posterior (A-P) displacements and in situ forces of the ACL under 110 N of anterior tibial loading of 30 degrees, 60 degrees, and 90 degrees of knee flexion. The knee was then reconstructed with a BPTB autograft, and the distal end of the graft was fixed sequentially at three different locations in each specimen--proximal, central, distal. A-P testing was repeated for each fixation site, and the resulting knee kinematics and the in situ forces of the grafts were compared to the intact case. The site of tibial fixation was demonstrated to have a significant effect on the resulting anterior displacement and internal rotation of the tibia as well as the in situ forces of the graft. Proximal fixation produced the most stable knee (A-P displacements reduced to 120% of intact at 30 degrees and 170% at 90 degrees), becoming significantly less stable with more distal fixation. These results suggest that proximal graft fixation may provide the most acute stability of the reconstructed knee.

Animals↗

PubMed2003

Anatomic rotational relationships of the proximal tibia, distal femur, and patella: implications for rotational alignment in total knee arthroplasty.

The orientation of the femur, tibia, and patella are important considerations in total knee arthroplasty. Our goal was to describe the relationships between the femoral epicondylar (FE) axis, posterior femoral (PF) axis, posterior tibial (PT) axis, patellar (PAT) axis, and patellar ligament (PL). A secondary goal was to determine where the short axis of the tibial tray intersects the patellar ligament as a function of tibial component rotation. Thirty normal magnetic resonance imaging (MRI) scans were analyzed. Strong relationships were found between the FE and PAT axes (2 degrees +/- 3 degrees, r(2) = 0.73), and between the FE and PF axes (6 degrees +/- 2 degrees, r(2) = 0.77). When the tibial baseplate was aligned along the PT axis, 30% of the cases were in an ideal position. When the FE axis was used, 73% were ideal.

Adult↗

PubMed1993

Radiological analysis of normal axial alignment of femur and tibia in view of total knee arthroplasty.

Alignment of the anatomical and mechanical axes of the lower extremities was analyzed using standardized radiographs in two series of 66 femur and 44 tibia specimens. A new anatomical axis, the distal femoral anatomical axis, was introduced. This axis corresponds to the overall femoral anatomical axis and encloses a valgus angle of 6 degrees with the mechanical axis of the femur. It allows for design of shorter intramedullary guiding instruments that will still be in congruency with true femur geometry. Comparison with computerized calculations of angles on computed tomography scans on a series of 38 bones shows a high precision of measurement on standard radiographs in neutral rotation.

Adult↗

PubMed1987

Bone mineral density of the proximal tibia following uncemented arthroplasty.

Bone mineral density (BMD, g/cm2) was measured using dual-photon absorptiometry (DPA) in selected areas of the proximal tibia following uncemented PCA knee prosthesis. In nine patients with 14 alloplastic operations, measurements were taken at 3-6-month intervals for the first 3 1/2 years after operation. There was a significant increase in BMD of about 15% during the first 6 months after operation. The following year it remained increased, although not significantly, compared with the initial values, then gradually diminished. Increased bone density after arthroplasty may be explained mainly by stimulation of bone formation from weight bearing due to improved walking ability. Stress shielding of the proximal part of the supporting tibial bone did not seem to occur.

Adult↗

PubMed1999

Preoperative bone mineral density of the proximal tibia and migration of the tibial component after uncemented total knee arthroplasty.

Twenty-two patients with primary osteoarthrosis of the knee all operated on with insertion of an uncemented total knee arthroplasty had a preoperative measurement of bone mineral density (BMD) in the coronal plane of the proximal tibia performed by dual-photon absorptiometry. Postoperatively and with follow-up after 6 weeks (n = 21), 1 year (n = 22), and 3 years (n = 19), radiographs suitable for radiostereometric analysis of the tibial component migration were obtained. One year postoperatively, stress examinations were performed with the aim of measuring inducible displacement of the tibial component. Most of the migration, expressed as maximal total point motion (MTPM), occurred during the first year with an average migration of approximately 1 mm. Regression analysis showed a positive relation between BMD and MTPM after 6 weeks (P = .03, r = .47), 1 year (P = .0005, r = .68), and 3 years (P = .02, r = .54). Inducible displacement did not reveal any significant relation to BMD. MTPM between 1 and 3 years, which is the clinically most important parameter with respect to later loosening of the tibial component, showed a negative relation to BMD (P = .04, r = -.47). Thus, tibial components of knees with preoperative high tibial BMD showed less continuous migration.

Aged↗

PubMedDate not supplied

Dysplasia epiphysealis hemimelica of the proximal tibia showing epiphyseal osteochondroma in an adult.

A 33-year-old woman was referred to our hospital complaining of pain and a tumorous lesion in her left knee joint in the absence of any history of trauma. Radiological examinations demonstrated an osseous mass originating from the epiphysis of the proximal tibia, with a continuous osteoblastic lesion involving the lateral half of the epiphysis. The pathological diagnosis of these lesions was compatible with that of osteochondroma. The clinical and pathological features of this case were considered to be identical with those of dysplasia epiphysealis hemimelica, although this patient was older than patients described in previous reports, and demonstrated no other symptoms such as valgus or varus deformity or limb-length discrepancy.

Adult↗

PubMed1996

Influence of mono- and bicortical anchorage on the integration of titanium implants. A study in the rabbit tibia.

The study aimed to evaluate the removal torque and bone tissue response to titanium implants supported by one or two cortical layers. A total of 72 screw titanium implants, either 10 or 16 mm in length and 3.75 mm in diameter, were inserted in right and left tibiae of 18 adult New Zealand rabbits. The implants engaged either one or two cortical layers, and the animals were allowed a healing period of 6 or 12 weeks. The degree of integration was assessed by measuring the removal torque with a torque gauge manometer. Histomorphometric calculations were also performed in 10-microns-thick ground sections. All implants were clinically stable at the end of the experiment. The removal torque was two times higher for the bicortical implants after 6 weeks, and three times higher after 12 weeks, than for the monocortical ones. The 16-mm implants also showed a statistically higher amount of bone contact and bone area after 6 and 12 weeks, respectively, than the short ones. The results support bicortical anchorage of implants also in the clinical situation.

Animals↗

PubMed1997

Reintegration of mobilized titanium implants. An experimental study in rabbit tibia.

The possibility of re-establishing a rigid bone-implant fixation, i.e. osseointegration, after mechanical loosening of titanium implants, was evaluated in the rabbit tibia. Implants were inserted to engage either one (10 mm long, n = 24) or two (16 mm long, n = 24) cortical layers and were allowed to heal for six weeks. A re-entry was then made and 12 test implants in each group subjected to a reverse torque procedure until the integration failed. The remaining nonrotated 24 implants were left as controls. Thereafter all implants were allowed to heal for an additional period of six weeks. At the end of the 12 weeks, the degree of integration was assessed by measuring the removal torque for six test and six control implants in each group of implant lengths. Histomorphometric measurements were also performed on ground sections of the remaining test and control implants. A statistically significant higher removal torque was observed for the monocortical test implants than for the corresponding control implants. No differences were seen for the bicortical implants of either kind, however, no morphological differences could be revealed either, when comparing monocortical and bicortical test and control implants. These results indicate that osseointegrated implants that have been mobilized due to a traumatic disruption of the bone-implant interface, may reintegrate if allowed to heal for an additional period of time.

Animals↗

PubMed1998

Stability assessments and histology of titanium implants placed simultaneously with autogenous onlay bone in the rabbit tibia.

A disc-shaped bone graft was harvested from the calvarium in ten rabbits and anchored as an onlay bone graft, using a titanium implant, at the proximal tibial metaphysis. The contralateral tibia served as the control, where an implant was placed without a graft with the implant head at a height corresponding to the thickness of the graft on the test side. Resonance frequency measurements were performed 4, 8, 16 and 24 weeks postoperatively and removal torque measurements were performed at 24 weeks. A statistically significant higher implant stability, as assessed by resonance frequency measurements (RFM), was measured from 4 weeks throughout the 24-week period. The mean peak removal torque for the test implants was 50.4+/-10.0 Ncm and 30.0+/-6.9 Ncm for the control implants, which was a statistically significant difference. Histologically, the grafted bone was well incorporated and morphometry revealed more bone around the test implants. Calculations of shear stresses indicated that the grafted bone had similar biomechanical properties to the cortical bone of the recipient site. It is concluded that the integration of titanium implants in autogenous onlay bone grafts results in an increased biomechanical support of the implant. The use of RFM may also serve as a useful instrument for noninvasive monitoring of implant stability in vivo.

Animals↗

PubMed1998

A study of different calcification areas in newly formed bone 8 weeks after insertion of dental implants in rabbit tibias.

In orofacial implantology there are many types of implants for the different systems. Among these is the implant surface type, e.g., a screw type, cylindrical and laminar. Furthermore, the implants are different in their dimensions, their metal composition, their surface condition, such as smooth, grit or layered surfaces and in their methods of application. Two different self-tapping implants, one smooth and the other grit-blasted, are screwed into the bone, and another one with a plasma of titanium coating, which is also in a screw form but with greater spaces between the screw threads are compared. The greatest amount of bone deposition in the bone/implant interface was encountered in the latter one, the smooth surfaced implant being in second place. All of these systems can alter the implant healing process and to demonstrate this, we injected bone markers in the rabbits over different periods of time so as to observe the different areas of bone deposition in the tibias where the implants had been inserted. The bone tracers used were Alizarin, Calcein and Xylenol-orange. The amount of deposition was calculated by using the method of surface morphometry.

Animals↗