Ivan Hvid | University of Oslo (original) (raw)

Papers by Ivan Hvid

PubMed, 2004

Osteoarthritis is a chronic joint disease with pathological changes in the articulating cartilage... more Osteoarthritis is a chronic joint disease with pathological changes in the articulating cartilage and all other tissues that occupy the joint. Radin and coworkers have suggested the involvement of subchondral bone in the disease process. However, evidence for an essential role in the etiology has never been proven. Recent studies showing reduced chemical and mechanical properties of subchondral bone in various stages of the disease have invigorated interest in the role of subchondral bone in the development and progression of the disease. The current study showed that the concept of bone adaptation might explain subchondral stiffening, a process where subchondral bone becomes typically sclerotic in osteoarthritis. In addition, we report reduced mechanical matrix tissue properties as well as an increase in denatured collagen content. In conclusion, although osteoarthritic bone tissue contains increased denatured collagen and has reduced matrix mechanical properties, the widely accepted concept of subchondral stiffening is compatible with the process of normal bone adaptation.

Clinical Orthopaedics and Related Research, Feb 1, 1988

The axial strength of trabecular bone at the knee is critical for the maintenance of support and ... more The axial strength of trabecular bone at the knee is critical for the maintenance of support and fixation of the prosthetic components after total surface knee arthroplasty. The resistance of trabecular bone to penetration was measured posteriorly, centrally, and anteriorly in each of the tibial and femoral condyles in 150 consecutive total knee arthroplasties. Forty-seven rheumatoid knees and 88 osteoarthritic knees were evaluated. The correlation of bone strength with selected clinical parameters was found to be too poor to predict bone strength. Tibial bone strength was lower in rheumatoid than in osteoarthritic knees. Steroid medication did not influence tibial bone strength in rheumatoid arthritis. The distribution of bone strength between the medial and lateral condyles was closely dependent on knee alignment, with high medial strength in varus knees. At the unloaded condyle, strength was reduced relative to the findings for normally aligned knees. At the tibia, strength decreased with depth from the resection surface, while at the femur the converse was true. Tibial bone strength, both condylar and overall average, was lower than values reported in studies of normal cadaver knees. Evaluation of the absolute bone strength at the tibial condyles suggested that the values too low to meet load-bearing requirements after well-aligned knee replacement were infrequent.

Engineering in Medicine, 1988

In order to optimize non-destructive mechanical testing of trabecular bone specimens, different t... more In order to optimize non-destructive mechanical testing of trabecular bone specimens, different techniques were analysed, and correlations were established between properties derived from such non-destructive testings and those derived from destructive testing. Non-destructive testing to a fixed percentage of predicted ultimate stress was hampered by inaccuracy of this prediction. Simulation of non-destructive testing conducted to the linear' part of the compression curve using a drop of the increase of the stiffness (slope of the compression curve) below a certain value as stop criterion revealed strong correlations ( r: 0.97–0.99) between the stiffness at the stop point and modulus of elasticity derived from destructive testing. However, trabecular damage will probably occur during such testing because high strain values were obtained. Testing to a fixed strain (0.6 per cent) also revealed strong correlation between the stiffness at the 0.6 per cent strain level and modulus of elasticity ( r = 0.96) derived from destructive testing. By this technique trabecular damage was avoided and standardized elastic and viscoelastic energies could be obtained. Prediction of modulus of elasticity by indirect methods such as modulus of elasticity of specimens from the opposite symmetric location ( r = 0.73), bone mineral concentration ( r = 0.72) derived from photon absorptiometry and the CT number ( r = 0.78) derived from quantitative computed tomography showed less strong correlations.

Journal of Orthopaedic Research, Mar 1, 2003

Introduction: Therapeutic angiogenesis, a novel concept in tissue engineering, is neo-formation o... more 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 miniosmotic 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.

Acta Orthopaedica Scandinavica, 1984

Total condylar 1 knee arthroplasty Prosthetic component positioning and radiolucent lines Prosthe... more Total condylar 1 knee arthroplasty Prosthetic component positioning and radiolucent lines Prosthetic positioning and overall postoperative alignment were studied in 138 consecutive total knee replacements, using the InsalYBursteinm total condylar knee system. Overall alignment was within 7 _+ 5 degrees of valgus in 63 per cent of the knees, while tibial component positioning was within 4 degrees of tilt in any direction in 53 per cent of the knees. A radiolucency index incorporating width and extent of radiolucent zones at the tibia was shown to progress from 3 months to 2 years postoperatively. The radiolucency index 2 years postoperatively was higher with postoperative varus alignment in the rheumatoid arthritis group; a tibial component tilt of more than 4 degrees in any direction increased the radiolucency index in both treatment groups.

Journal of Biomechanics, 1991

The effect of strain rate (a) and apparent density (p) on stiffness (E), strength (a,,), and ulti... more The effect of strain rate (a) and apparent density (p) on stiffness (E), strength (a,,), and ultimate strain (E,) was studied in 60 human trabecular bone specimens from the proximal tibia. Testing was performed by uniaxial compression to 5% specimen strain. Six different strain rates were used: 0.0001, 0.001, 0.01, 0.1, 1, and 10 s-l. Apparent density ranged between 0.23 and 0.59 gcme3. Linear and non-linear regression analyses using strength, stiffness and ultimate strain as dependent variables (Y) and strain rate and apparent density as independent variables were performed using the following models: Y = apbF, Y=pb(o+ci; Y=(o+bp)&, Y=apZF, E=a$C. The variations of strength and stiffness were explained equally well by the linear and the power function relationship to strain rate. The exponent was 0.07 in the power function relationship between strength and strain rate and 0.05 between stiffness and strain rate. The variation of ultimate strain was explained best using a power function relationship to strain rate (exponent =0.03). The variation of strength and stiffness was explained equally well by the linear, power function and quadratic relationship to apparent density. The cubic relationship between stiffness and apparent density showed a less good fit. Ultimate' strain varied independently of apparent density.

Journal of Biomechanics, 1990

CRC Press eBooks, Nov 29, 1999

Journal of Biomechanics, Jul 1, 1998

Engineering in Medicine, Jul 1, 1985

In the evaluation and treatment of knee ligament injuries and for comprehensive understanding of ... more In the evaluation and treatment of knee ligament injuries and for comprehensive understanding of knee ligament function, it is important to know where in the movement of extension-flexion the different types of instability released by wellknown ligament injuries occur. An apparatus was developed to record anterior– posterior tibial displacement, valgus–varus instability, and axial tibial rotation instability on knee preparations, continuously, in the extension–flexion movement, when the tibia was submitted to a well-defined constant torque or force. Osteoligamentous knee preparations were suspended in the femur and a lever was fixed to the tibial segment. The lever was fitted with strain gauges to measure the torque in three planes. Potentiometers recording extension–flexion, anterior–posterior tibial displacement, valgus–varus, and axial rotation angulations were mounted. The lever was moved manually, and signals from strain gauges and potentiometers passed through an amplifier and a data acquisition system to a microcomputer, which stored the results of the measurements. The final movement curves were calculated and plotted at a regional computer service centre. Tests for reproducibility of measurements at different ligament status demonstrated a high level of reproducibility.

Clinical Biomechanics, May 1, 1986

A three-dimensional finite element stress analysis was employed to calculate stresses in a distal... more A three-dimensional finite element stress analysis was employed to calculate stresses in a distal tibia modelled with three simple total ankle joint replacement tibia1 components. The bone was modelled as a composite structure consisting of cortical and trabecular bone in which the trabecular bone was either homogeneous with a constant modulus of elasticity or heterogenous with experimentally determined heterogeneity. The results were sensitive to variations in trabecular bone material property distributions, with lower stresses being calculated in the heterogeneous model. An anterolateral application of load, which proved the least favourable, was used in comparing the prosthetic variants. Normal and shear stresses at the trabecular bone-cement interface and supporting trabecular bone were slightly reduced by addition of metal backing to the polyethylene articular surface, and a further reduction to very low values was obtained by addition of a long intramedullary peg bypassing stresses to the cortical bone. Relevance Mechanical loosening of the tibia1 component in total ankle joint replacement is a major cause of clinical failure. This investigation suggests that a desirable reduction of cementbone interface and trabecular bone stresses can be obtained by relatively simple design alterations, although none of the models investigated seems ideal for clinical use.

Acta Orthopaedica Scandinavica, 1981

A case of clinically successful autografting of rib perichondrium to the patella in a 55-year-old... more A case of clinically successful autografting of rib perichondrium to the patella in a 55-year-old woman suffering from painful traumatic chondromalacia patellae is reported. A postoperative arthrogram however did not show any significant regeneration of cartilage but arthroscopy revealed a smooth surface of cartilage on the patella. Biopsies were not performed.

Clinical Orthopaedics and Related Research, Feb 1, 1987

Acta Orthopaedica Scandinavica, 1986

Seminars in Hematology, 2006

Although often overlooked, the life of the patient with severe hemophilia is characterized by bot... more Although often overlooked, the life of the patient with severe hemophilia is characterized by both intermittent and chronic pain. Bleeds into joints and muscles cause extensive pressure on sensory nerves and, following recurrent bleeds, joint destruction, and synovial reaction is accompanied by constant pains that are frequently mistaken for further bleeding. The orthopedic surgeon may break the vicious cycle of chronic synovitis by excising inflamed and hypertrophic synovium or severely damaged cartilage and adjacent bone ends, and implanting an artificial joint. Numerous technical solutions are now available and orthopedic surgery is increasingly on offer to those hemophilia patients who, since childhood, have been victims of insufficiently treated bleeds because no or limited treatment was available, and because the concept of prophylaxis had not yet been developed. Nonetheless, orthopedic surgery in patients with hemophilia requires much more effort and planning than surgery in non-hemophilic patients. In this overview, we will address issues related to surgery in hemophilic patients, as well as some practical issues related to the timing of surgery, preoperative testing, perioperative hemostasis, and patient rehabilitation.

Clinical Biomechanics, Jun 1, 1998

Objective. This study investigates the age-related variations in the mechanical properties of the... more Objective. This study investigates the age-related variations in the mechanical properties of the normal human tibia1 cartilagebone complex and the relationships between cartilage and bone. Design. A novel technique was applied to assess the mechanical properties of the cartilage and bone by means of testing the cartilage-bone complex. Background. Up to now, mechanical testing of cartilage and bone has been reported separately, and little is known about the mechanical behaviour of both tissues when examined as a unit. Methods. Cylindrical human proximal tibia1 cartilage-bone complex specimens from 31 normal donors aged 16-83 years were tested in compression. The deformation was measured simultaneously in bone and cartilage to obtain the mechanical properties of both tissues. Results. The stiffnesses and elastic energies of both cartilage and bone showed an initial increase, with maxima at 40 years, followed by a steady decline. The viscoelastic energy was maximal at younger ages (16-29 years), followed by a steady decline. The energy absorption capacity did not vary with age. Stiffnesses and elastic energies were correlated significantly between cartilage and bone. Conclusions. The present study demonstrates that similar age-related trends were seen in cartilage and bone, as if they behaved as a single mechanical unit. Relevance The basic information presented here on the mechanical properties of cartilage and bone and the correlations between them reveals the unit function of both tissues that are of importance for the understanding of the etiology and pathogenesis of degenerative joint diseases, such as arthrosis.

The journal of bone and joint surgery, Nov 1, 1997

We tested in compression specimens of human proximal tibial trabecular bone from 31 normal donors... more We tested in compression specimens of human proximal tibial trabecular bone from 31 normal donors aged from 16 to 83 years and determined the mechanical properties, density and mineral and collagen content. Young's modulus and ultimate stress were highest between 40 and 50 years, whereas ultimate strain and failure energy showed maxima at younger ages. These age-related variations (except for failure energy) were non-linear. Tissue density and mineral concentration were constant throughout life, whereas apparent density (the amount of bone) varied with ultimate stress. Collagen density (the amount of collagen) varied with failure energy. Collagen concentration was maximal at younger ages but varied little with age. Our results suggest that the decrease in mechanical properties of trabecular bone such as Young's modulus and ultimate stress is mainly a consequence of the loss of trabecular bone substance, rather than a decrease in the quality of the substance itself. Linear regression analysis showed that collagen density was consistently the single best predictor of failure energy, and collagen concentration was the only predictor of ultimate strain.

Annals of Surgery, Nov 1, 1982

ABSTRACT

Journal of Orthopaedic Research, May 1, 1989

Human trabecular bone specimens (n = 121) from the proximal tibial epiphysis of nine macroscopica... more Human trabecular bone specimens (n = 121) from the proximal tibial epiphysis of nine macroscopically normal cadaver knees were tested nondestructively to a fixed strain (0.6%) for analysis of unloading energy and hysteresis energy followed by a destructive test for analysis of work to failure. All energy properties showed interindividual variation (p < 0.005). There was a strong positive correlation between unloading energy and both stress (r = 0.95) and stiffness (r = 0.89) determined at 0.6% strain. A less strong, but statistically significant, correlation was found between hysteresis energy and stress (r = 0.82) and stiffness (r = 0.76) at 0.6% strain. There was a negative correlation between the loss tangent and stiffness at 0.6% strain (r = −0.40, p < 0.001). Work to failure correlated positively with modulus of elasticity (r = 0.75), ultimate stress (r = 0.92), and ultimate strain (r = 0.51). There was a positive mutual correlation between all energy properties (p < 0.001).

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PubMed, May 13, 2002

Children's fractures are a challenge to the treatment system, in that 17,000 children are treated... more Children's fractures are a challenge to the treatment system, in that 17,000 children are treated in Denmark each year. The true burden on patients and society is unknown. It is estimated that 1000 new-born infants are treated for hip instability in Denmark per year, and 30 are diagnosed late. Ultrasound scanning is recommended for secondary screening and selective screening of children at risk. Identification of acetabular dysplasia followed by surgical correction could be an important prophylactic measure, with a potential reduction in expenses to society. To some extent, congenital clubfoot is hereditary. Environmental factors are important, maternal smoking being one. Early operative treatment yields good results. There is a need for prospective registration. Perthes' disease is an idiopathic necrosis of the capital femoral epiphysis. Passive smoking is a significant factor. A young age (< 7 years) and limited necrosis carry a good prognosis, and active treatment can improve the prognosis for the other patients.