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PubMed2006

Comparison of mechanical debridement and radiofrequency energy for chondroplasty in an in vivo equine model of partial thickness cartilage injury.

OBJECTIVE: The purpose of this study was to develop a long-term model of cartilage injury that could be used to compare the effects of radiofrequency energy (RFE) and mechanical debridement as a treatment. METHODS: Partial thickness fibrillation of patellar cartilage was created in 16 mature ponies. Three months after the initial surgery all injured patellae were randomly selected to receive one of the four treatments (n = 8/treatment): (1) control, (2) mechanical debridement with a motorized shaver, (3) TAC-CII RFE probe, and (4) CoVac 50 RFE probe. The ponies were euthanized 22 months after treatment. Macroscopic appearance of the cartilage surface was scored, vital cell staining was used to determine chondrocyte viability and light microscopy was used to grade the morphometric changes within the cartilage. Mechanical properties (aggregate modulus, Poisson's ratio and permeability) also were determined and compared to normal uninjured cartilage. RESULTS: There were no differences in the cartilage surface scores among the treatment groups and control samples (P > 0.05). The maximum depth of cell death and the percentage of dead area in control and mechanical debridement groups were significantly less than those in both RFE groups. There were no significant differences in maximum depth and the percentage of dead area between the two RFE treatment groups. Histologic scores demonstrated better cartilage morphology for the control and mechanical debridement groups than those of RFE groups. However, even with full thickness chondrocyte death, the matrix in the RFE treated sections was still retained and the mechanical properties of the treated cartilage did not differ from the mechanical debridement group. CONCLUSION: RFE caused greater chondrocyte death and more severe morphological changes compared to untreated degenerative cartilage and mechanical debridement in this model.

Animals↗
PubMed2003

Measurement accuracy of focal cartilage defects from MRI and correlation of MRI graded lesions with histology: a preliminary study.

OBJECTIVES: Although accurate spatial measurement of cartilage thickness from MRI is possible, no studies have assessed the accuracy of measuring cartilage defect dimensions from MRI. In addition, current MR grading scales for assessing cartilage lesions have limited categories, and little is known about how well these scales correlate with histological assessment of the lesion. The objective of this preliminary study is to address both these issues. METHODS: We performed two experiments on four cadaver knee joints from elderly donors: Experiment 1 assessed the accuracy of measuring controlled defects in cartilage, and Experiment 2 compared MRI grading (Noyes scale) of natural cartilage lesions to histological grading (Mankin scale) of the sectioned cartilage tissue. MRI was performed on 1.5 T clinical scanner (fat-suppressed 3D-SPGR at TR/TE/alpha=55/13.5/45 and 256 x 256 matrix). RESULTS: The mean difference between defect diameters measured and introduced was less than 0.1mm, which was statistically insignificant (P=0.754). Defect depth was less accurate at >0.4mm, significantly under predicting actual defect depth (P=0.004). Correlation between Noyes grading scores and Mankin grading scores of natural lesions was moderately high (r=0.7) and statistically significant (P=0.001). CONCLUSIONS: Three-dimensional mapping of cartilage thickness shows great promise for the accurate measurement of focal cartilage defects, though improvement is needed. The Noyes grading scale is consistent with histological Mankin grading of cartilage lesions, though enhancement of MR grading scales is needed, and warranted, based on the signal intensity information available from clinical MRI. Integration of these two analyses-focal defect measurement and signal intensity analysis-could potentially result in a valuable clinical tool for early osteoarthritis diagnosis and longitudinal tracking.

Aged↗
PubMed1999

Gender differences in knee cartilage volume as measured by magnetic resonance imaging.

OBJECTIVE: The aim of this study was to analyze sex differences in knee cartilage volume. METHODS: Articulate cartilage volumes were determined by processing images acquired in the sagittal plane using T1-weighted fat saturation magnetic resonance on an independent work station. The knees of 28 subjects (17 male, 11 female) who underwent MRI for clinical indications (pain <3 months) but who had a normal X-ray and structurally normal MRI were examined. RESULTS: Males had significantly larger cartilage volumes than females, with difference in cartilage volume remaining statistically significant after adjusting for age, height, weight and bone volume. The differences for males relative to females were: femoral cartilage volume [4.1 ml 95% CI (2.0, 6.1)]; and patella cartilage volume [1.4 ml (0.2, 2.7)]. Although not statistically significant, the tibial cartilage volume also showed these sex differences. Exploratory analysis indicated an increasing gender difference with increasing age for patellar cartilage volume. CONCLUSION: Men have significantly larger knee cartilage volume than women, independent of body and bone size. The mechanisms for this will need to be determined.

Adult↗
PubMed2001

Expression of vitamin D receptors and matrix metalloproteinases in osteoarthritic cartilage and human articular chondrocytes in vitro.

OBJECTIVES: To examine the in situ distributions of vitamin D receptors (VDR) and matrix metalloproteinases (MMPs) in osteoarthritic cartilage for comparison with non-arthritic, normal cartilage; and to assess the in vitro effects of 1alpha,25 dihydroxyvitaminD(3)(1alpha,25(OH)(2)D(3)) on MMPs-1, -3 and -9 and prostaglandin E(2)(PGE(2)) production by cultures of human articular chondrocytes (HAC) shown to be VDR-positive. METHODS: Using immunohistochemistry VDR expression in different specimens of osteoarthritic cartilage (N=11) was compared to that in normal cartilage (N=6), along with the immunodetection of MMPs-1, -3 and -9. The effects of 1alpha25(OH)(2)D(3)on MMP and PGE(2)production by HAC in vitro, with and without stimulation by TNFalpha or phorbol myristate acetate (PMA), was evaluated using ELISA methodology. RESULTS: VDR was demonstrated in HAC of all specimens of osteoarthritic cartilage, especially the superficial zone, whereas only two of five normal cartilage specimens were VDR(+)for a minor proportion of HAC. Immunolocalization of MMPs-1, -3 and -9 was often seen in areas where chondrocytes were VDR(+), and dual immunolocalization has demonstrated individual chondrocytes positive for both VDR and MMP-3 in situ. In vitro, 1alpha25(OH)(2)D(3)alone had no effect on MMP-1, -9 and PGE(2)production by HAC, but MMP-3 production was up-regulated by 1alpha25(OH)(2)D(3)either with or without stimulation with TNFalpha or PMA. By contrast the increased production of MMP-9 and PGE(2)induced by PMA was significantly suppressed by concomitant treatment with 1alpha25(OH)(2)D(3). CONCLUSIONS: The demonstration of VDR expression by HAC in osteoarthritic cartilage was often associated with sites where MMP expression was prevalent, observations in contrast to their virtual absence in normal age-matched cartilage. Together with HAC in vitro studies, the data suggests that 1alpha25(OH)(2)D(3)contributes to the regulation of MMP and PGE(2)production by HAC in osteoarthritic cartilage.

Aged↗
PubMed1994

[Autoantibodies against cartilage components: clinical relevance for reconstructive surgery in the area of the head and neck].

The clinical relevance of antibodies against components of cartilage in the reconstructive surgery has not yet been clarified. In our study four groups of patients with successful and unsuccessful autologous cartilage transplantation in rhinosurgery, patients with ear perichondritis and patients with tracheal stenosis after long-term intubation were investigated for the presence of a humoral immune reactivity to cartilage. The control groups consisted of healthy persons and patients with RA. The antibodies against cartilage matrix and chondrocytes were determined using indirect immunofluorescence methods. Patients with unsuccessful cartilage transplantation showed increased antibodies against autologous cartilage (until 1:100) compared to the patients with successful cartilage transplantation. Furthermore, patients suffering from ear perichondritis and tracheal stenosis showed also increased antibodies against cartilage. These data suggest that a humoral immune reactivity against autologous cartilage--independent of an infection--can be one cause for the destruction of cartilaginous tissue.

Adult↗
PubMed2002

Novel mechano-acoustic technique and instrument for diagnosis of cartilage degeneration.

Fibrillation of articular surface and depletion of proteoglycans are the structural changes related to early osteoarthrosis. These changes make cartilage softer and prone to further degeneration. The aim of the present study was to combine mechanical and acoustic measurements towards quantitative arthroscopic evaluation of cartilage quality. The performance of the novel ultrasound indentation instrument was tested with elastomers and bovine articular cartilage in vitro. The instrument was capable of measuring elastomer thickness (r = 1.000, p < 0.01, n = 8) and dynamic modulus (r = 0.994, p < 0.01, n = 13) reliably. Osteochondral plugs were tested before and after enzymatic degradation of cartilage proteoglycans by trypsin or chondroitinase ABC, and of cartilage collagens by collagenase. Trypsin and collagenase induced a mean decrease of -31.2 +/- 12.3% (+/- SD, p < 0.05) and -22.9 +/- 20.8% (p = 0.08) in dynamic modulus, respectively. Rate of cartilage deformation, i.e. creep rate, increased by +117.8 +/- 71.4% (p < 0.05) and +24.7 +/- 35.1% (p = 0.17) in trypsin and chondroitinase ABC treatments, respectively. Collagenase induced a greater decrease in the ultrasound reflection from the cartilage surface (-54.2 +/- 29.6%, p < 0.05) than trypsin (-17.1 +/- 13.5%, p = 0.08). In conclusion, combined quantitation of tissue modulus, viscoelasticity and ultrasound reflection from the cartilage surface provides a sensitive method to distinguish between normal and degenerated cartilage, and even to discern proteoglycan loss and collagen degradation from each other.

Animals↗
PubMed2000

MRI techniques in early stages of cartilage disease.

Cartilage degenerative diseases affect millions of people. Our understanding of these diseases and our ability to establish efficacious treatment strategies have been confounded by the difficulty of nondestructively evaluating the state of cartilage. Imaging strategies that allow visualization of cartilage integrity would revolutionize the field by allowing us to visualize early stages of degeneration and thus to evaluate predisposing factors for cartilage disease and changes resulting from interventions (eg, therapies) in culture studies, tissue-engineered systems, animal models, and in vivo in humans. Here we briefly review current state-of-the-art MRI strategies relevant to understanding and following treatment in early cartilage degeneration. We review MRI as applied to the assessment of the whole joint, of cartilage as a whole (as an organ), of cartilage tissue, and of cartilage molecular composition and structure. Each of these levels is amenable to assessment by MRI and offers different information that, in the long run, will serve as an important element of cartilage imaging.

Animals↗
PubMedDate not supplied

Articular cartilage lesions in 993 consecutive knee arthroscopies.

BACKGROUND: Traumatic articular cartilage injuries heal poorly and may lead to development of osteoarthritis at a young age. This study estimates the number of patients who may benefit from one of the surgical methods of cartilage repair. METHODS: All patients undergoing knee arthroscopy during a 6-month period at three collaborating hospitals were consecutively evaluated according to the International Cartilage Repair Society (ICRS) knee form. The material consists of 993 consecutive knee arthroscopies in patients with median age of 35 years. RESULTS: Preoperative radiographs demonstrated degenerative changes in 13% of the knees. Articular cartilage pathology was found in 66% and a localized cartilage defect was found in 20% of the knees. A localized full-thickness cartilage lesion (ICRS grade 3 and 4) was observed in 11% of the knees. Of the localized full-thickness lesions, 55% (6% of all knees) had a size above 2 cm(2). CONCLUSION: Eleven percent of all knee arthroscopies show cartilage defects that may be suitable for cartilage repair procedures. However, the natural history of these lesions and the number of patients that will benefit from a cartilage repair procedure are so far unknown.

Adolescent↗
PubMed1993

Cell origin and differentiation in the repair of full-thickness defects of articular cartilage.

The origin and differentiation of cells in the repair of three-millimeter-diameter, cylindrical, full-thickness drilled defects of articular cartilage were studied histologically in New Zealand White rabbits. The animals were allowed to move freely after the operation. Three hundred and sixty-four individual defects from 122 animals were examined as long as forty-eight weeks postoperatively. In the first few days, fibrinous arcades were established across the defect, from surface edge to surface edge, and this served to orient mesenchymal cell ingrowth along the long axes. The first evidence of synthesis of a cartilage extracellular matrix, as defined by safranin-O staining, appeared at ten days. At two weeks, cartilage was present immediately beneath the surface of collagenous tissue that was rich in flattened fibrocartilaginous cells in virtually all specimens. At three weeks, the sites of almost all of the defects had a well demarcated layer of cartilage containing chondrocytes. An essentially complete repopulation of the defects occurred at six, eight, ten, and twelve weeks, with progressive differentiation of cells to chondroblasts, chondrocytes, and osteoblasts and synthesis of cartilage and bone matrices in their appropriate locations. At twenty-four weeks, both the tidemark and the compact lamellar subchondral bone plate had been re-established. The cancellous woven bone that had formed initially in the depths of the defect was replaced by lamellar, coarse cancellous bone. Autoradiography after labeling with 3H-thymidine and 3H-cytidine demonstrated that chondrocytes from the residual adjacent articular cartilage did not participate in the repopulation of the defect. The repair was mediated wholly by the proliferation and differentiation of mesenchymal cells of the marrow. Intra-articular injections of 3H-thymidine seven days after the operation clearly labeled this mesenchymal cell pool. The label, initially taken up by undifferentiated mesenchymal cells, progressively appeared in fibroblasts, osteoblasts, articular chondroblasts, and chondrocytes, indicating their origin from the primitive mesenchymal cells of the marrow. Early traces of degeneration of the cartilage matrix were seen in many defects at twelve to twenty weeks, with the prevalence and intensity of the degeneration increasing at twenty-four, thirty-six, and forty-eight weeks. Polarized light microscopy demonstrated failure of the newly synthesized repair matrix to become adherent to, and integrated with, the cartilage immediately adjacent to the drill-hole, even when light microscopy had shown apparent continuity of the tissue. In many instances, a clear gap was seen between repair and residual cartilage.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

[Tissue engineering: new treatment of cartilage alterations in degenerative joint diseases in horses--preliminary results of a long term study].

Degenerative alterations in fetlock joints of the forelimb are common diagnoses for horses. The hyaline cartilage has a low capacity to regenerate and the treatment by veterinarians is often insufficient. As a final result, horses with articular cartilage defects are often not able to take part in competitions anymore. To establish an autologous cartilage repair method, we set artificial lesions (8 mm in diameter) into the fetlock joints of the forelimb of three horses. These defects were closed with autologous chondrocyte implants, which were fixed with titan-suture-anchors. After 3, 12 and 24 months, biopsies were taken by arthroscopy. One horse was euthanized after 9, another one after 24 months. The repair tissue was examined histologically and by biochemical analysis of hydroxyproline and glycosaminoglycan, which are typical cartilage related substances. After 9 months, the integration of the implant into native cartilage was demonstrated by electron microscopy. After 24 months, histological staining showed a similar morphology of the cartilage repair tissue compared with the surrounding native cartilage. Biochemical analysis of typical cartilage matrix molecules revealed formation of hyaline-like cartilage within tissue engineered autologous chondrocyte transplants.

Animals↗
PubMed2004

[Culture of mice marrow stromal stem cells in human acellular cartilage matrix].

OBJECTIVE: To study the feasibility of using mice marrow stromal stem cells(MSCs) as seed cells for tissue engineering cartilage to embed the seed cells in acellular cartilage matrix of human auricle. METHODS: Acellular cartilage matrix was made from human auricle cartilage. The MSCs were isolated from the nucleated cells fraction of mice marrow by centrifuge. The MSCs were embedded in acellular cartilage matrix. After 10 day's combined culture, the specimens were observed with optical and electrical microscope. RESULTS: The MSCs could well proliferate in the acellular cartilage matrix. The cells were not well-distributed in acellular cartilage matrix. There were more cells in the peripheral part of the matrix than in the central part of the matrix. Most of the cells were in cartilaginous lacunae. There were 1 or 2 cells in every cartilaginous lacunae. CONCLUSION: The MSCs can be used as seed cells of tissue engineering and can well proliferate in the acellular cartilage matrix and become tissue engineering cartilage.

Animals↗
PubMed2004

[Value of autologous chondrocyte transplantation in experimental cartilage defects reconstruction. Part IV--Microscopic analysis of repair tissue degenerative changes (cellularity and signs of necrosis)].

UNLABELLED: Articular cartilage cells are immersed in semi-solid matrix and isolated from the rest of the body because of lack of nervous fibres, and blood and lymphatic vessels. Trauma and aging processes result in cartilage ultrastructure disorders. Those changes leads to progressive decreasing of durability and rigidity of cartilage. Research on articular cartilage reconstruction focuses on, among other things, reaching by newly formed tissue optimal amount of vital cells. The aim of this part of the study was microscopic evaluation of repair tissue degenerative changes (cellularity and signs of necrosis). MATERIAL AND METHODS: Repair of partial thickness cartilage defect (III tertiary grade) on distal femur joint surface was evaluated (25 adolescent rabbits). Procedures were performed in two groups: I--autologous chondrocyte transplantation under periosteal flap, II--periosteal graft. Chondrocytes were isolated from the cartilage specimens by enzymatic digestion and cultured in vitro. The follow-up periods were established at 4, 8 and 12 weeks. Repair tissue was evaluated microscopically according to modified O'Driscoll scale. RESULTS: Repair tissue cellularity. In group I (with chondrocytes), 4 weeks after the procedure tissue of high cellularity was formed, corresponding in amount of cells to the structure of early differentiated hyaline-like cartilage. Amount of cells slightly decreased with time, as it occurs in maturing cartilage. In group II (without chondrocytes), 4 weeks after the procedure the repair tissue was characterized by small amount of cells, which was decreasing with time. Signs of necrosis. In group I, 4, 8 and 12 weeks after the procedure moderate intensity of necrotic signs was observed. In group II, significant intensity of necrosis signs in all observation periods was observed. CONCLUSION: Obtained results indicate, that autologous chondrocyte transplantation in treatment of partial thickness cartilage defects effects with forming tissue of high cellularity, not degenerating with time, much better as compared to untreated defect.

Animals↗
PubMed1985

[Studies on normal and pathological human cartilage proteoglycans with metrizamide density gradient ultracentrifugation].

In order to study human articular cartilage proteoglycans (PG) in aging and pathological states, PG extracts of normal cartilage, osteoarthritic cartilage, chondrosarcoma and osteochondroma were subjected to the density gradient ultracentrifugation in 23% metrizamide-6M urea system. Normal cartilages have chondroitin sulfate rich PG and keratan sulfate rich PG. The latter has a higher buoyant density and increases markedly with aging, but is missing in all of the pathological cartilages tested which have juvenile profiles corresponding to the normal cartilage of a child under 10 years of age. No differences in the chain lengths of glycosaminoglycans were observed in any of the cartilages tested, but marked differences were observed in the aggregation PG and hyaluronate in the pathological cartilages. The molecular sizes of hyaluronate are probably small in normal adults but large in the pathological state. Determinations of hexose and uronate distribution in the density gradient characterize easily the differences in aging and pathological cartilages. This system provided more information than the CsCl-guanidine HCl system.

Adolescent↗
PubMed1978

Articular cartilage degradation and the pathology of haemophilic arthropathy.

Synovial membrane and specimens of articular cartilage, obtained from the affected knee joints of 5 haemophilic patients at the time of surgical synovectomy, were studied. All the synovial specimens showed villous proliferation and multiplication of synovial cells. Haemosiderin granules were present within synovial cells and in macrophages. There was congestion and capillary proliferation. An inflammatory infiltrate of plasma cells and lymphocytes was seen in some instances. Articular cartilage changes were classified into the following 4 grades according to severity: 1--an increase in the number of surface chondrocytes with fibrous metaplasia, and the appearance of superficial fissures; 2--a fibrous vascularized overgrowth, resembling rheumatoid pannus; 3--deep fissuring and necrosis of cartilage; 4--erosion and disappearance of articular cartilage with exposure of subchondral bone. In the first 3 grades, deep nests of chondrocytes containing haemosiderin were present. These cell aggregates became larger and more degenerate as cartilage degradation progressed. Damaged articular cartilage was deficient in glycosaminoglycan (acid mucopolysaccharide). No excess enzyme activity could be demonstrated within the cartilage matrix. Immunofluorescent studies were not helpful. Electron microscopical examination revealed siderosomes within degenerate chondrocytes and synovial cells. Granules resembling haemosiderin were also present in the cartilage matrix. It is considered that iron products affect both chondrocytes and matrix adversely and play a part in articular cartilage destruction in haemophilia.

Adolescent↗
PubMed2002

Developing an anatomical model of the human laryngeal cartilages from magnetic resonance imaging.

The purpose of this work was to construct a three-dimensional anatomical framework of the cartilages of the human larynx. The framework included representative surface models of the four laryngeal cartilages and estimated attachment points for the intrinsic laryngeal muscles. High-resolution magnetic resonance imaging (MRI) was used to scan one female and four male human cadaveric larynges. The cartilages were segmented manually from the MRI volume for analysis. Two of these larynges were subsequently dissected and the landmark distances on the cartilages measured for comparison with the MRI measures and previous studies. The MRI measures were 8% smaller than the anatomical measures and 12% smaller than data reported in the literature. A laryngeal coordinate system was defined using the plane of symmetry of the cricoid cartilage. Measures of cricoid cartilage symmetry had less than 3% difference between the two sides for a series of measures. An algorithm for registering larynges that minimized the root-mean-square distance between the surface of a reference cricoid cartilage and the surfaces of nonisotropically scaled candidate cricoid cartilages was evaluated. This study provided an anatomical framework for registering different larynges to the same coordinate space.

Aged↗
PubMedDate not supplied

Viability of crushed and diced cartilage grafts: a study in rabbits.

OBJECTIVE: To investigate the effects of dicing and different degrees of crushing on cartilage graft viability and outcome in rhinoplasty. METHODS: Cartilage was harvested from both ears of 29 rabbits. For each animal, 6 cartilage pieces were prepared as follows and inserted into the paraspinal subcutaneous tissue: (1) left intact, (2) diced to approximately 1 x 1-mm pieces and then wrapped in oxidized regenerated cellulose, (3) slightly crushed, (4) moderately crushed, (5) significantly crushed, and (6) severely crushed. Animals were killed at 2, 5, and 10 months, and graft specimens were microscopically examined. RESULTS: As crushing intensity rose, cartilage viability decreased and more cartilage tissue was transformed to connective tissue. The intact and slightly crushed grafts showed significant chondrocyte proliferation. This decreased as crushing intensity increased, and the severely crushed and diced cellulose-wrapped grafts exhibited almost no peripheral chondrocyte proliferation. CONCLUSIONS: Slight crushing of a cartilage graft can produce outstanding graft material that forms softer nasal contours and fills defects well. However, severe crushing of cartilage grafts results in extensive necrosis and eventual reduction in graft volume. The use of oxidized regenerated cellulose to wrap diced cartilage grafts also tends to reduce clinical predictability owing to negative effects on cartilage viability and regeneration.

Animals↗
PubMed1997

Tumefactive cartilage proliferation after rhinoplasty. A newly reported complication.

OBJECTIVE: To describe and document the development of tumoral proliferation of cartilage in 4 patients after nasal surgery, a complication that, to our knowledge, has not been reported before. DESIGN: Similar postoperative nasal masses were excised from 4 patients who underwent rhinoplasty. Histopathologic evaluation was carried out to identify the nature of the lesions and to provide a basis for rational management of similar lesions subsequently encountered. SETTING: Academic tertiary referral center. PARTICIPANTS: Four healthy patients (3 women and 1 man) ranging in age from 21 to 49 years. Two of the patients underwent routine rhinoplasty with resection of cephalic margins of alar cartilages, and 2 underwent augmentation procedures with implantation of auricular cartilage. INTERVENTION: Discrete firm masses were excised from each patient's nose approximately 1 year after the most recent rhinoplastic procedure was performed. Histological evaluation was carried out on each specimen. RESULTS: All 4 masses were found to consist of tumefactive proliferation of cartilage. Clonal proliferation and mild nuclear atypia were observed. CONCLUSIONS: After rhinoplasty, progressive asymmetrical fullness in or adjacent to cartilaginous structures or graft material should suggest the possibility of tumefactive proliferation of cartilage and should be evaluated with surgical exploration. All areas of thickened cartilage should be excised completely, with immediate auricular cartilage reconstruction of resulting anatomical defects. Perichondrium should be completely removed from auricular cartilage implants in the nose, and mechanical injury to the graft should be minimized. We strongly caution against morsellizing dorsal cartilage implants for nasal reconstruction.

Adult↗
PubMed1999

In vivo characterization of indentation stiffness of articular cartilage in the normal human knee.

Previous laboratory measurements showed topographical variation in the properties of articular cartilage in several animal species and in humans. In this study we characterize for the first time the topographical variation of the stiffness of the human knee articular cartilage in vivo using a novel arthroscopic indentation instrument. The instrument indicates the stiffness in the form of force (Newtons) by which the tissue resists the constant deformation (300 microm) produced by the small (1-mm diameter) cylindrical indenter. Measurements were carried out at eight sites in the knee joint of 20 persons who had intact cartilage in the arthroscopic examination. The stiffest cartilage (5.6 +/- 1.2 N, mean +/- SD) was located in the lateral condyle of the femur, whereas the softest cartilage (2.4 +/- 0.8 N) was in the medial plateau of the tibia. In general, the cartilage stiffness was higher in the femur than in the tibia (p < 0. 01) or in the patella (p < 0.01). In the femur, the condyles were stiffer than the patellar surface (p < 0.01). The stiffness variation was consistent with earlier biphasic indentation analyses of laboratory measurements with the knee joint cartilage of cadavers. This study provides baseline data for characterization of cartilage stiffness in pathological situations or follow-up of the cartilage quality after surgical interventions.

Adolescent↗