Biomedical subjects

Jukka S Jurvelin

Publications and source records attributed to Jukka S Jurvelin.

At least 19 recordsLinked to original sources

PubMed2006

Characterization of articular cartilage by combining microscopic analysis with a fibril-reinforced finite-element model.

Load-bearing characteristics of articular cartilage are impaired during tissue degeneration. Quantitative microscopy enables in vitro investigation of cartilage structure but determination of tissue functional properties necessitates experimental mechanical testing. The fibril-reinforced poroviscoelastic (FRPVE) model has been used successfully for estimation of cartilage mechanical properties. The model includes realistic collagen network architecture, as shown by microscopic imaging techniques. The aim of the present study was to investigate the relationships between the cartilage proteoglycan (PG) and collagen content as assessed by quantitative microscopic findings, and model-based mechanical parameters of the tissue. Site-specific variation of the collagen network moduli, PG matrix modulus and permeability was analyzed. Cylindrical cartilage samples (n=22) were harvested from various sites of the bovine knee and shoulder joints. Collagen orientation, as quantitated by polarized light microscopy, was incorporated into the finite-element model. Stepwise stress-relaxation experiments in unconfined compression were conducted for the samples, and sample-specific models were fitted to the experimental data in order to determine values of the model parameters. For comparison, Fourier transform infrared imaging and digital densitometry were used for the determination of collagen and PG content in the same samples, respectively. The initial and strain-dependent fibril network moduli as well as the initial permeability correlated significantly with the tissue collagen content. The equilibrium Young's modulus of the nonfibrillar matrix and the strain dependency of permeability were significantly associated with the tissue PG content. The present study demonstrates that modern quantitative microscopic methods in combination with the FRPVE model are feasible methods to characterize the structure-function relationships of articular cartilage.

Animals↗

PubMed2006

Quantitative ultrasound imaging detects degenerative changes in articular cartilage surface and subchondral bone.

Previous studies have suggested that quantitative ultrasound imaging could sensitively diagnose degeneration of the articular surface and changes in the subchondral bone during the development of osteoarthrosis (OA). We have recently introduced a new parameter, ultrasound roughness index (URI), for the quantification of cartilage surface roughness, and successfully tested it with normal and experimentally degraded articular surfaces. In this in vitro study, the applicability of URI was tested in bovine cartilage samples with spontaneously developed tissue degeneration. Simultaneously, we studied the sensitivity of quantitative ultrasound imaging to detect degenerative changes in the cartilage-bone interface. For reference, histological degenerative grade of the cartilage samples was determined. Mechanical reference measurements were also conducted. Cartilage surface roughness (URI) was significantly (p<0.05) higher in histologically degenerated samples with inferior mechanical properties. Ultrasound reflection at the cartilage-bone interface was also significantly (p<0.05) increased in degenerated samples. Furthermore, it was quantitatively confirmed that ultrasound attenuation in the overlying cartilage significantly affects the measured ultrasound reflection values from the cartilage-bone interface. To conclude, the combined ultrasound measurement of the cartilage surface roughness and ultrasound reflection at the cartilage-bone interface complement each other, and may together enable more sensitive and quantitative diagnosis of early OA or follow up after surgical cartilage repair.

Algorithms↗

PubMed2006

Ultrasonic characterization of human trabecular bone microstructure.

New quantitative ultrasound (QUS) techniques involving ultrasound backscattering have been introduced for the assessment of bone quality. QUS parameters are affected by the transducer characteristics, e.g. frequency range, wave and pulse length. Although frequency-dependent backscattering has been studied extensively, understanding of the ultrasound scattering phenomenon in trabecular bone is still limited. In the present study, the relationships between QUS parameters and the microstructure of human trabecular bone were investigated experimentally and by using numerical simulations. Speed of sound (SOS), normalized broadband ultrasound attenuation (nBUA), average attenuation, integrated reflection coefficient (IRC) and broadband ultrasound backscatter (BUB) were measured for 26 human trabecular bone cylinders. Subsequently, a high-resolution microCT system was used to determine the microstructural parameters. Moreover, based on the sample-specific microCT data, a numerical model for ultrasound propagation was developed for the simulation of experimental measurements. Experimentally, significant relationships between the QUS parameters and microstructural parameters were demonstrated. The relationships were dependent on the frequency, and the strongest association (r = 0.88) between SOS and structural parameters was observed at a centre frequency of 5 MHz. nBUA, average attenuation, IRC and BUB showed somewhat lower linear correlations with the structural properties at a centre frequency of 5 MHz, as compared to those determined at lower frequencies. Multiple regression analyses revealed that the variation of acoustic parameters could best be explained by parameters reflecting the amount of mineralized tissue. A principal component analysis demonstrated that the strongest determinants of BUB and IRC were related to the trabecular structure. However, other structural characteristics contributed significantly to the prediction of the acoustic parameters as well. The two-dimensional numerical model introduced in the present study demonstrated good agreement with the experimental measurements. However, further studies with the simulation model are warranted to systematically investigate the relation between the structural parameters and ultrasound scattering.

Absorptiometry, Photon↗

PubMed2006

Collagen network of articular cartilage modulates fluid flow and mechanical stresses in chondrocyte.

The extracellular matrix of articular cartilage modulates the mechanical signals sensed by the chondrocytes. In the present study, a finite element model (FEM) of the chondrocyte and its microenvironment was reconstructed using the information from fourier transform infrared imaging spectroscopy. This environment consisted of pericellular, territorial (mainly proteoglycans), and inter-territorial (mainly collagen) matrices. The chondrocyte, pericellular, and territorial matrix were assumed to be mechanically isotropic and poroelastic, whereas the inter-territorial matrix, due to its high collagen content, was assumed to be transversely isotropic and poroelastic. Under instantaneous strain-controlled compression, the FEM indicated that the fluid pressure within the chondrocyte increased nonlinearly as a function of the in-plane Young's modulus of the collagen network. Under instantaneous force-controlled compression, the chondrocyte experienced the highest fluid pressure when the in-plane Young's modulus of the collagen network was approximately 4 MPa. Based on the present results, the mechanical characteristics of the collagen network of articular cartilage can modify fluid flow and stresses in chondrocytes. Therefore, the integrity of the collagen network may be an important determinant in cell stimulation and in the control of the matrix maintenance.

Biophysical Phenomena↗

PubMed2006

Collagen network primarily controls Poisson's ratio of bovine articular cartilage in compression.

The equilibrium Young's modulus of articular cartilage is known to be primarily determined by proteoglycans (PGs). However, the relation between the Poisson's ratio and the composition and structure of articular cartilage is more unclear. In this study, we determined Young's modulus and Poisson's ratio of bovine articular cartilage in unconfined compression. Subsequently, the same samples, taken from bovine knee (femoral, patellar and tibial cartilage) and shoulder (humeral cartilage) joints, were processed for quantitative microscopic analysis of PGs, collagen content, and collagen architecture. The Young's modulus, Poisson's ratio, PG content (estimated with optical density measurements), collagen content, and birefringence showed significant topographical variation (p < 0.05) among the test sites. Experimentally the Young's modulus was strongly determined by the tissue PG content (r = 0.86, p < 0.05). Poisson's ratio revealed a significant negative linear correlation (r = -0.59, p < 0.05) with the collagen content, as assessed by the Fourier transform infrared imaging. Finite element analyses, conducted using a fibril reinforced biphasic model, indicated that the mechanical properties of the collagen network strongly affected the Poisson's ratio. We conclude that Poisson's ratio of articular cartilage is primarily controlled by the content and organization of the collagen network.

Animals↗

PubMed2006

Influence of overlying soft tissues on trabecular bone acoustic measurement at various ultrasound frequencies.

Ultrasound (US) has been introduced as a promising tool for osteoporosis diagnostics. However, soft tissues overlying the bones affect reliability of the ultrasound (US) techniques. In this in vitro study, the effect of soft tissues on bone US measurements was investigated numerically and experimentally. Particularly, the dependence of the error induced by soft tissues on the applied US frequency (0.3 to 6.7 MHz) was addressed. For these aims, human trabecular bone samples (n = 25) were measured using acoustic, dual energy x-ray absorptiometry (DXA) and mechanical techniques. US attenuation, speed, reflection and backscattering were determined from the through-transmission and pulse-echo measurements. Numerical correction, based on the inclusion of acoustic characteristics of specific soft tissue components, i.e., adipose and lean tissues, was derived for the analysis of experimental measurements. Values of US parameters, interrelationships between the US parameters and mechanical properties, as well as the errors induced by the soft tissues, were significantly dependent on the US frequency. The errors induced by the soft tissues on the US measurement were typically reduced by approximately 50% after introduction of the numerical correction technique. Thereby, the acoustic prediction of mechanical properties of trabecular bone was also improved. We conclude that the numerical correction of the contribution of overlying soft tissues on acoustic measurements can reduce uncertainties related to in vivo US measurements.

Absorptiometry, Photon↗

PubMed2006

In situ and ex vivo evaluation of an arthroscopic indentation instrument to estimate the health status of articular cartilage in the equine metacarpophalangeal joint.

OBJECTIVE: To evaluate an arthroscopic indentation instrument (Artscan 200) for assessment of the health status of equine articular cartilage. STUDY DESIGN: In vitro experiment using equine isolated proximal phalanx (P1) specimens. SAMPLE POPULATION: P1 specimens from 39 horses (aged 1.5-22 years). METHODS: Reproducibility was tested by determination of the coefficient of variation (CV). Dynamic modulus and cartilage degeneration index (CDI) values were measured at 2 predefined sites (site 1, joint margin; site 2, joint center) to assess the accuracy and to evaluate the relation with surface integrity. RESULTS: CV was 9.0%. A significant decrease in indenter force was identified when dynamic modulus values decreased to <2.5 MPa (range of tested samples 0.9-8.1 MPa) and when CDI values at site 1 increased to >50% (range 5.4-72.8%). CONCLUSIONS: Technique reproducibility was adequate but accuracy was limited. The device identified degeneration-associated decreases in cartilage stiffness only when the mechanical properties of the cartilage were considerably changed. CLINICAL RELEVANCE: Usefulness of this indentation instrument during arthroscopic surgery would be limited in the initial phase of OA-like cartilage degeneration, but may yield important information in more advanced OA.

Animals↗

PubMed2005

Associations between grip strength change and axial postmenopausal bone loss--a 10-year population-based follow-up study.

The aim of the present study was to investigate the associations between grip strength change and postmenopausal bone loss. The study population, 622 peri- and postmenopausal women, was a random sample of the OSTPRE-study cohort (n=13,100) in Kuopio, Finland. Bone mineral density (BMD) at the lumbar spine (LS) and femoral neck (FN) was measured with dual X-ray absorptiometry and grip strength with a pneumatic squeeze dynamometer at baseline in 1989-1991, at the 5-year follow-up in 1994-1997 and at the 10-year follow-up in 1999-2001. Women were divided into three groups according to the change in age-grouped grip strength quartile they belonged to in each measurement (n in 5-year/10-year follow-up): "decreased" (n=150/n=140), "maintained" (n=314/n=320) and "improved" (n=158/n=162). Women within the improved group had significantly lower bone loss at both FN and LS in comparison to the other two groups after 10 years of follow-up (P<0.01). Furthermore, in HRT non-users (n=305) the difference between the improved group and maintained group was only modest (P=0.04). In contrast, in HRT users (n=310) the mean annual BMD change among the improved group was positive (bone gain 0.11%/year) and differed significantly in comparison to modest bone loss in the decreased and maintained groups in both LS and FN (P<0.01). The linear trend between grip strength quartile change and LS/FN bone loss was significant in HRT users (P<0.001) in contrast to HRT non-users (P=NS) in the linear regression model. Any of these differences were not affected by adjustments for age, weight, height and other potential confounders. In conclusion, the present study suggests that improvement in age-grouped grip strength quartile is strongly associated with axial bone loss among postmenopausal women. This effect seemed to interact positively with estrogen repletion status. These results encourage performing further clinical studies on associations between muscle strength changes and bone loss.

Absorptiometry, Photon↗

PubMed2005

Fracture risk and bone density of peri- and early postmenopausal women with uterine leiomyomas.

OBJECTIVES: Fracture risk and bone mineral density (BMD) among peri- and early postmenopausal women with leiomyomas requiring hysterectomy was evaluated. METHODS: We counted fractures among women with or without leiomyomas using data from the Kuopio Osteoporosis Study. The study population consisted of 6086 women aged 47-56 years with never-use of hormone replacement therapy (HRT) responding to the baseline and 5-year follow-up inquiries. Part of the sample (n=1271) underwent bone densitometry. RESULTS: Hysterectomy was carried out in 927 women, and 59% reported that this was attributable to leiomyomas. The hazard ratio (HR) was 0.68 (95% CI 0.49-0.94) for any and 0.73 (95% CI 0.43-1.26) for distal forearm fracture among women with leiomyomas compared to those without any. Among women postmenopausal at baseline, the corresponding HRs were 0.62 (95% CI 0.44-0.87) and 0.54 (95% CI 0.31-0.96); after adjusting for age, time since menopause weight, height and previous fracture 0.69 (95% CI 0.49-0.97) and 0.63 (95% CI 0.35-1.11). The baseline BMDs were 1.15 g/cm2 among hysterectomized leiomyoma and 1.12 g/cm2 (ns) among non-hysterectomized women at lumbar (L2-L4), and 0.94 and 0.93 g/cm2 (ns) at femoral sites. The follow-up lumbar BMDs were 1.13 and 1.09 g/cm2 (p<0.001) and the corresponding femoral values were 0.90 and 0.89 g/cm2 (ns), respectively. Among postmenopausal women, the corresponding baseline lumbar BMDs were 1.15 and 1.08 g/cm2 (p<0.001), femoral 0.93 and 0.90 g/cm2 (p=0.003); the follow-up lumbar BMDs 1.13 g/cm2 versus 1.07 g/cm2 (p<0.001); femoral BMDs 0.89 versus 0.87 (ns). CONCLUSIONS: Peri- and early postmenopausal women with a history of leiomyomas seem to have better BMD and less fractures compared with those without leiomyomas. This may be mediated through higher estrogen levels leading to higher BMD and the growth of leiomyomas.

Absorptiometry, Photon↗

PubMed2005

Site-specific ultrasound reflection properties and superficial collagen content of bovine knee articular cartilage.

Previous quantitative 2D-ultrasound imaging studies have demonstrated that the ultrasound reflection measurement of articular cartilage surface sensitively detects degradation of the collagen network, whereas digestion of cartilage proteoglycans has no significant effect on the ultrasound reflection. In this study, the first aim was to characterize the ability of quantitative 2D-ultrasound imaging to detect site-specific differences in ultrasound reflection and backscattering properties of cartilage surface and cartilage-bone interface at visually healthy bovine knee (n = 30). As a second aim, we studied factors controlling ultrasound reflection properties of an intact cartilage surface. The ultrasound reflection coefficient was determined in time (R) and frequency domains (IRC) at medial femoral condyle, lateral patello-femoral groove, medial tibial plateau and patella using a 20 MHz ultrasound imaging instrument. Furthermore, cartilage surface roughness was quantified by calculating the ultrasound roughness index (URI). The superficial collagen content of the cartilage was determined using a FT-IRIS-technique. A significant site-dependent variation was shown in cartilage thickness, ultrasound reflection parameters, URI and superficial collagen content. As compared to R and IRC, URI was a more sensitive parameter in detecting differences between the measurement sites. Ultrasound reflection parameters were not significantly related to superficial collagen content, whereas the correlation between R and URI was high. Ultrasound reflection at the cartilage-bone interface showed insignificant site-dependent variation. The current results suggest that ultrasound reflection from the intact cartilage surface is mainly dependent on the cartilage surface roughness and the collagen content has a less significant role.

Animals↗

PubMed2005

Prediction of density and mechanical properties of human trabecular bone in vitro by using ultrasound transmission and backscattering measurements at 0.2-6.7 MHz frequency range.

The ultrasound (US) backscattering method has been introduced as an alternative for the through-transmission measurement of sound attenuation and speed in diagnosis of osteoporosis. Both attenuation and backscattering depend strongly on the US frequency. In this study, 20 human trabecular bone samples were measured in transmission and pulse-echo geometry in vitro. The aim of the study was to find the most sensitive frequency range for the quantitative ultrasound (QUS) analyses. Normalized broadband US attenuation (nBUA), speed of sound (SOS), broadband US backscatter (BUB) and integrated reflection coefficient (IRC) were determined for each sample. The samples were spatially scanned with five pairs of US transducers covering a frequency range of 0.2-6.7 MHz. Furthermore, mechanical properties and density of the same samples were determined. At all frequencies, SOS, BUB and IRC showed statistically significant linear correlations with the mechanical properties or density of human trabecular bone (0.51 < r < 0.82, 0.54 < r < 0.81 and 0.70 < r < 0.85, respectively). In contrast to SOS, IRC and BUB, nBUA showed statistically significant correlations with mechanical parameters or density at the centre frequency of 1 MHz only. Our results suggest that frequencies up to 5 MHz can be useful in QUS analyses for the prediction of bone mechanical properties and density. Since the use of higher frequencies provides better axial and spatial resolution, improved structural analyses may be possible. While extensive attenuation of high frequencies in trabecular bone limits the clinically feasible frequency range, selection of optimal frequency range for in vivo QUS application should be carefully considered.

Algorithms↗

PubMed2005

Feasibility of the use of a novel soft tissue stiffness meter.

Simple but objective measurement of soft tissue consistency would be advantageous in the assessment of many neurological, lymphostatic and venous disorders. The aim of the present study was to evaluate the feasibility of using a novel hand-held computerized soft tissue stiffness meter (STSM). The STSM describes the soft tissue stiffness (STS) in the form of the instantaneous force (N) by which the tissue resists the constant deformation produced by a cylindrical intender. Firstly, the STSM was used to test elastomer samples with known mechanical properties. In the in vivo assessment, 12 healthy, nondisabled adults (age range, 24-57 years) and 16 subjects with chronic myofascial neck pain syndrome (age range, 27-55 years) were studied. To study the reproducibility (coefficient of variation (CV(%))) of the method, the measurement sites were either marked with a marker pen (marked points) or localized anatomically (unmarked points). Measurements were made from the dorsal forearm (Arm), trapezius (Tra), levator scapulae (Lev), infraspinatus (Inf) and deltoideus (Del) muscle areas. STS in the forearm was studied during different types of short-term relative isometric loading of the muscle as well as during venous occlusion. STS values of the myofascial trigger points in the Lev muscles were evaluated bilaterally. A linear, positive relationship was found between the indenter force (N) and the dynamic compressive modulus (MPa) of elastomer stiffness (r(2) = 0.90, n = 9). Intra- and interrater CVs of marked and unmarked sites varied between 4.31% and 12.06%. STS increased linearly along the relative muscle load (r(2) = 0.96) and nonlinearly during the venous occlusion (r(2) = 0.97). Statistically significant regional variation of STS was found between the different measurement sites (p < 0.05). In conclusion, STSM can evaluate tissue stiffness quantitatively and yield reproducible data.

Adult↗

PubMed2005

Improvement of arthroscopic cartilage stiffness probe using amorphous diamond coating.

During arthroscopic evaluation of articular cartilage unstable contact and even slipping of the measurement instrument on the tissue surface may degrade the reproducibility of the measurement. The main aim of the present study was to achieve more stable contact by controlling the friction between articular cartilage surface and the arthroscopic cartilage stiffness probe (Artscan 200, Artscan Oy, Helsinki, Finland) using amorphous diamond (AD) coating. In order to obtain surfaces with different average roughnesses (R(a)), polished stainless steel disks were coated with AD by using the filtered pulsed arc-discharge (FPAD) method. Dynamic coefficient of friction (mu) between the articular cartilage (n = 8) and the coated plates along one non-coated plate was then determined. The friction between AD and cartilage could be controlled over a wide range (mu = 0.027-0.728, p < 0.05, Wilcoxon test) by altering the roughness. Possible deterioration of cartilage was investigated by measuring surface roughness after friction tests and comparing it with the roughness of the adjacent, untested samples (n = 8). Importantly, even testing with the roughest AD (R(a) = 1250 nm) did not damage articular surface. On the basis of the friction measurements, a proper AD coating was selected for the stiffness probe. The performance of coated and non-coated probe was compared by measuring bovine osteochondral samples (n = 22) with both instruments. The reproducibility of the stiffness measurements was significantly better with the AD-coated probe (CV% = 4.7) than with the uncoated probe (CV% = 8.2). To conclude, AD coating can be used to safely control dynamic friction with articular surface. Sufficient friction between articular surface and reference plate of the arthroscopic probe improves significantly reproducibility of the stiffness measurements.

Animals↗

PubMed2005

Bone mineral density, body height, and vitamin D receptor gene polymorphism in middle-aged men.

BACKGROUND: Polymorphisms of the vitamin D receptor (VDR) gene have been suggested to account for some of the genetic variation in bone mass. However, the relationship has been controversial. It has been suggested that environmental factors such as physical activity may be one of the many reasons for this controversy.AIM. We investigated the possible interactions of VDR gene polymorphisms and low to moderate intensity exercise on bone mineral density (BMD) in a four-year controlled, randomized intervention trial in 140 middle-aged Finnish men. METHOD: The TaqI, FokI, and ApaI restriction fragment length polymorphism (RFLP)-markers of the VDR gene were evaluated. BMDs of the lumbar spine (L2-L4), femoral neck, and total proximal femur were measured with dual-energy X-ray absorptiometry (DXA). In addition, the relations of the VDR gene polymorphism with bone turnover markers (serum tartrate-resistant acid phosphatase (TRAP) 5b activity and serum osteocalcin concentration) were evaluated. RESULTS: At the randomization, the subjects with the VDR TaqI Tt or tt genotype had a greater body height than the subjects with TT genotype (P=0.001). In addition, the association of VDR TaqI polymorphism with femoral BMD was found. The Tt or tt genotype associated with higher femoral neck values than the TT genotype (P=0.003) at randomization. After adjusting the femoral neck for body height, the association remained (P=0.021). We did not find any association between VDR gene polymorphism and bone turnover markers or any interactions of VDR gene polymorphisms and exercise on BMD. CONCLUSIONS: The TaqI polymorphism may be associated with body height and femoral neck BMD values. The present findings also suggest that the VDR polymorphisms do not modify the effect of regular aerobic exercise on BMD. However, more randomized controlled exercise trials are needed to investigate the role of exercise intensity on VDR gene polymorphisms, and the role of VDR gene polymorphisms on BMD.

Body Height↗

PubMed2005

Indentation stiffness of repair tissue after autologous chondrocyte transplantation.

Our main hypothesis was that indentation stiffness of the repair tissue approaches the values of adjacent cartilage 1 year after autologous chondrocyte transplantation. We also wanted to investigate the differences between osteochondritic lesions and full-thickness lesions. Thirty patients with cartilage lesions were operated on with autologous chondrocyte transplantation. The repair was evaluated arthroscopically, indentation stiffness was measured, and clinical evaluations were done. The stiffness of the repair tissue improved to 62% (mean 2.04 +/- 0.83 N, mean +/- SD) of adjacent cartilage (3.58 +/- 1.04 N). Fifty-three percent of the patients graded their knee as excellent or good and 47% of the patients graded their knee as fair at the followup. In six patients the normalized stiffness was at least 80%, suggesting hyaline-like repair. The indentation stiffness of the osteochondritis dissecans lesion repairs (1.45 +/- 0.46 N; n = 7) was less than that of the nonosteochondritis dissecans lesion repair sites (2.37 +/- 0.72 N; n = 19). Gadolinium-enhanced magnetic resonance imaging of the cartilage (dGEMRIC) during followup of four patients suggested proteoglycan replenishment, although all grafts showed low indentation values. Low stiffness values may indicate incomplete maturation or predominantly fibrous repair. The indentation analysis showed that the repair tissue stiffness could, in some cases, reach the same level as the adjacent cartilage, but there was a large variation among the grafts.

Adolescent↗

PubMed2005

Arthroscopic cartilage indentation and cartilage lesions of anterior cruciate ligament-deficient knees.

BACKGROUND: The anterior cruciate ligament-deficient knee is prone to osteoarthritis and meniscus lesions. Very little, however, is known about the biomechanical properties of articular cartilage in anterior cruciate ligament-deficient knees. PURPOSE: To evaluate biomechanical and macroscopical cartilage changes in the knee joint with respect to the time after anterior cruciate ligament rupture. HYPOTHESIS: Chronic anterior cruciate ligament deficiency induces cartilage softening. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Cartilage stiffness of 50 patients undergoing anterior cruciate ligament reconstructive surgery because of symptomatic knee instability after chronic anterior cruciate ligament rupture was measured with an arthroscopic indenter device, and the number and size of cartilage lesions were evaluated. RESULTS: The cartilage stiffness did not correlate with time from trauma to surgery (r = 0.002, P = .99), but the number of cartilage lesions in the knee increased when the time from the initial trauma to reconstructive surgery increased (r = 0.356, P = .011). Indentation values measured on healthy-looking cartilage on damaged joint surfaces were lower than the values measured on healthy joint surfaces (P < .01 on lateral femoral condyle and on tibial plateaus). CONCLUSIONS: The number of cartilage lesions increases with increased time after initial trauma. The arthroscopic indenter device is able to detect cartilage softening as the early mechanical sign of degradation not yet visible to the eye.

Adolescent↗

PubMed2005

Influence of age, site, and degenerative state on the speed of sound in equine articular cartilage.

OBJECTIVE: To determine the speed of sound (SOS) in equine articular cartilage and investigate the influence of age, site in the joint, and cartilage degeneration on the SOS. SAMPLE POPULATION: Cartilage samples from 38 metacarpophalangeal joints of 38 horses (age range, 5 months to 22 years). PROCEDURE: Osteochondral plugs were collected from 2 articular sites of the proximal phalanx after the degenerative state was characterized by use of the cartilage degeneration index (CDI) technique. The SOS was calculated (ratio of needle-probe cartilage thickness to time of flight of the ultrasound pulse), and relationships between SOS value and age, site, and cartilage degeneration were evaluated. An analytical model of cartilage indentation was used to evaluate the effect of variation in true SOS on the determination of cartilage thickness and dynamic modulus with the ultrasound indentation technique. RESULTS: The mean SOS for all samples was 1,696 +/- 126 m/s. Age, site, and cartilage degeneration had no significant influence on the SOS in cartilage. The analytical model revealed that use of the mean SOS of 1,696 m/s was associated with maximum errors of 17.5% on cartilage thickness and 70% on dynamic modulus in an SOS range that covered 95% of the individual measurements. CONCLUSIONS AND CLINICAL RELEVANCE: In equine articular cartilage, use of mean SOS of 1,696 m/s in ultrasound indentation measurements introduces some inaccuracy on cartilage thickness determinations, but the dynamic modulus of cartilage can be estimated with acceptable accuracy in horses regardless of age, site in the joint, or stage of cartilage degeneration.

Aging↗

PubMed2005

Increased bone mineral content but not bone mineral density in the hip in surgically treated knee and hip osteoarthritis.

OBJECTIVE: The inverse relationship between the occurrence of osteoarthritis (OA) and osteoporosis is controversial. Some investigators have found higher bone mineral density (BMD) in the hips, lumbar spine, and other skeletal sites of patients with OA; others have not. We investigated the relationship between BMD and OA. METHODS: We compared the BMD, bone mineral content (BMC), and projected area of the femoral neck (FN) and trochanter (TR) of 99 women with a validated diagnosis of primary OA from the Kuopio Osteoporosis Risk Factor and Prevention Study (OSTPRE) cohort, with 2012 controls. The measurements were made twice in women aged 47-59 years in 1989-91, and then repeated in 1994-98. RESULTS: After correction for age, body mass index (BMI), menopausal status, and hormone replacement therapy use before inclusion, we found no significant difference in femoral BMD of the OA patients compared with controls at baseline and at 5-year followup (FN +2.7%, +4.6%, respectively; nonsignificant). However, the BMC was significantly higher in all regions of interest in OA patients at baseline [FN +8.3% (p = 0.004); TR +13.3% (p = 0.017)]. The projected area of FN was also significantly higher at baseline and followup in OA patients (FN +3.7%, +3.9%, respectively; p < 0.001). The projected area of the bones increased in all subjects over the followup period. The BMD decrease rate was higher in OA patients for all regions of interest during followup. CONCLUSION: Hip BMD of women treated surgically for hip or knee OA was not different from that of healthy controls when measured twice with a 5-year interval. However, at 5-year followup, OA can be accompanied by an increase in bone size or changes in shape, and faster loss of BMD.

Absorptiometry, Photon↗