Cartilage Repair Capacity within a Single Full-Thickness Chondral Defect in a Porcine Autologous Matrix-Induced Chondrogenesis Model Is Affected by the Location within the Defect.

OBJECTIVE: Large articular cartilage defects are a challenge to regenerative surgery. Biomaterial scaffolds might provide valuable support for restoration of articulating surface. The performance of a composite biomaterial scaffold was evaluated in a large porcine cartilage defect. DESIGN: Cartilage repair capacity of a biomaterial combining recombinant human type III collagen (rhCo) and poly-(l/d)-lactide (PLA) was tested in a porcine model. A full-thickness chondral defect covering the majority of the weightbearing area was inflicted to the medial femoral condyle of the right knee. Spontaneous cartilage repair and nonoperated healthy animals served as controls. The animals were sacrificed after a 4-month follow-up. The repair tissue was evaluated with the International Cartilage Repair Society (ICRS) macroscopic score, ICRS II histological score, and with micro-computed tomography. Additionally, histopathological evaluation of lymph nodes and synovial samples were done for toxicological analyses. RESULTS: The lateral half of the cartilage defect in the operated groups showed better filling than the medial half. The mean overall macroscopic score for the rhCo-PLA, spontaneous, and nonoperated groups were 5.96 ± 0.33, 4.63 ± 0.42, and 10.98 ± 0.35, respectively. The overall histological appearance of the specimens was predominantly hyaline cartilage in 3 of 9 samples of the rhCo-PLA group, 2 of 8 of the spontaneous group, and 9 of 9 of the nonoperated group. CONCLUSIONS: The use of rhCo-PLA scaffold did not differ from spontaneous healing. The repair was affected by the spatial properties within the defect, as the lateral part of the defect showed better repair than the medial part, probably due to different weightbearing conditions.

Long-term clinical and radiographic outcomes and patient satisfaction after adult spinal deformity correction.

BACKGROUND AND AIMS: Adult spinal deformity surgery has increased with the aging population and modern surgical approaches, although it has high complication and reoperation rates. The permanence of radiographic correction, mechanical complications, predictive factors for poor patient-reported outcomes, and patient satisfaction were analyzed. MATERIAL AND METHODS: A total of 79 adult patients were retrospectively analyzed at baseline and 1-9 years after adult spinal deformity correction between 2007 and 2016. Patient-reported outcomes (Oswestry Disability Index, visual analog scale, and Scoliosis Research Society-30 scores), changes in radiographic alignment, indications for reoperation, predictors of poor outcomes according to the Oswestry Disability Index and Scoliosis Research Society-30 scores, and patient satisfaction with management were studied. RESULTS: Oswestry Disability Index and visual analog scale scores (p = 0.001), radiographic correction of thoracic kyphosis, lumbar lordosis, and pelvic retroversion (p ⩽ 0.001) and sagittal vertical axis (p = 0.043) were significantly better at 4-5 years of follow-up than at baseline. The risk for the first reoperation owing to mechanical failure of instrumentation or bone was highest within the first year, at 13.9% (95% confidence interval = 8.0%-23.7%), and 29.8% (95% confidence interval = 19.4%-43.9%) at the 5-year follow-up. Oswestry Disability Index and Scoliosis Research Society-30 total scores had a good correlation (r = -0.78; 95% CI = -0.86 to -0.68; p < 0.001). Satisfaction with management was correlated with patient-reported outcomes. Male sex and depression (p = 0.021 and 0.018, respectively) predicted poor outcomes according to the Oswestry Disability Index and/or Scoliosis Research Society-30 score. CONCLUSION: The achieved significant radiographic correction was maintained 5 years postoperatively. Despite reoperations, patient satisfaction and clinical outcomes were good. Depression and male sex predicted poor clinical outcomes.

Sixfold Post-Fracture Mortality in 16- To 30-Year-Old Patients-Suicides, Homicides, and Intoxications Among Leading Causes of Death.

BACKGROUND AND AIMS:: The death of any young individual is associated with the loss of many potentially fulfilling years of life. It has been suggested that the relative mortality of fracture patients may be higher in younger age groups than in older cohorts. We determined the mortality and causes of death in a cohort of 16- to 30-year-old patients that had been hospitalized for fractures. MATERIAL AND METHODS:: We collected data using criteria based on the diagnosis code (International Statistical Classification of Diseases and Related Health Problems, 10th Revision), surgical procedure code (Nordic Medico-Statistical Committee), and seven additional characteristics of patients admitted to the trauma ward at the Central Finland Hospital between 2002 and 2008. Patients were then followed to ascertain their mortality status until the end of 2012. Standardized mortality ratios were calculated and causes of death were determined by combining our registry data with data provided by Statistics Finland. RESULTS:: During the study, 199 women and 525 men aged 16-30 years had sustained fractures. None of these patients died during the primary hospital stay. At the end of follow-up (mean duration 7.4 years), 6 women and 23 men had died. The standardized mortality ratio for all patients was 6.2 (95% Confidence Interval: 4.3-8.9). Suicides and intoxications comprised over half, and motor vehicle accidents and homicides comprised nearly a third of the post-fracture deaths. CONCLUSION:: We found a concerning increase in mortality among young adults that had been hospitalized due to a fracture compared to the general population that had been standardized by age, sex, and calendar-period. Leading causes of death were suicides and intoxications or motor vehicle accidents and homicides, which may be indicative of depressive disorders or impulse control disorders, respectively. Identification of the underlying psychosocial problems may provide an opportunity for preventive interventions.

Exercise therapy is evidence-based treatment of shoulder impingement syndrome. Current practice or recommendation only.

BACKGROUND: Subacromial impingement syndrome is the most common indication for shoulder operation. However, exercise therapy for the conservative treatment is recommended in the first instance. AIM: To evaluate the implementation of exercise therapy in impingement syndrome. DESIGN: Retrospective study using structured postal questionnaire and data collected from hospital archive. METHODS: A total of 104 consecutive patients who had undergone shoulder surgery due to impingement syndrome. Patients were asked about therapy modalities that they had received before and after the operation as well as pain (VAS) and functional impairment (ASES) at one-year follow-up. RESULTS: Before surgery 49% of patients had not received advice for shoulder muscle exercises. After operation all patients had received mobility exercises, but one quarter of patients still reported that they had not received instructions about shoulder strength exercises. At the follow-up the means of the ASES index was 85 and use of NSAID had decreased by 75%. However, 15% of patients had moderate functional impairment (ASES under 60). CONCLUSION: About half of patients reported that they had not received advice for rotator cuff exercise therapy before surgery even though with it surgery would probably have been avoided in many cases. Although symptoms in most patients had decreased after operation, several patients still suffered from pain and decreased function. Still several patients had not received advice for shoulder strengthening exercises that are important to recovery. CLINICAL REHABILITATION IMPACT: The adherence to the current recommendations about exercise therapy is insufficient in clinical practice. Thus we recommend that it should be monitored in all institutions in which shoulder pain is treated.

Comparison of ultrasound and optical coherence tomography techniques for evaluation of integrity of spontaneously repaired horse cartilage.

The aim of this study was to compare sensitivity of ultrasound and optical coherence tomography (OCT) techniques for the evaluation of the integrity of spontaneously repaired horse cartilage. Articular surfaces of horse intercarpal joints, featuring both intact tissue and spontaneously healed chondral or osteochondral defects, were imaged ex vivo with arthroscopic ultrasound and laboratory OCT devices. Quantitative ultrasound (integrated reflection coefficient (IRC), apparent integrated backscattering coefficient (AIB) and ultrasound roughness index (URI)) and optical parameters (optical reflection coefficient (ORC), optical roughness index (ORI) and optical backscattering (OBS)) were determined and compared with histological integrity and mechanical properties of the tissue. Spontaneously healed tissue could be quantitatively discerned from the intact tissue with ultrasound and OCT techniques. Furthermore, several significant correlations (p < 0.05) were detected between ultrasound and OCT parameters. Superior resolution of OCT provided a more accurate measurement of cartilage surface roughness, while the ultrasound backscattering from the inner structures of the cartilage matched better with the histological findings. Since the techniques were found to be complementary to each other, dual modality imaging techniques could provide a useful tool for the arthroscopic evaluation of the integrity of articular cartilage.

Arthroscopic subacromial decompression: outcome comparison between outpatient and hospitalized patients with 2- to 5-year follow-up.

BACKGROUND AND AIMS: The purpose of this study was to evaluate the mid-term result of the arthroscopic subacromial decompression after failed conservative treatment of shoulder pain caused by subacromial impingement, when the patients were treated as an outpatient way or by staying overnight in hospital after surgery (hospitalized patients). Our hypothesis was that the results would be equal in both groups. MATERIAL AND METHODS: Arthroscopic subacromial decompression was performed in 80 consecutive patients, of which 40 patients were treated as an outpatient way (Outpatient Group), and 40 patients as a hospitalized way (Hospitalized Group). A prospective, comparative 2- to 5-year follow-up study including clinical examination, radiographic evaluation, isometric elevation strength measurements, as well as the University of California, Los Angeles (UCLA) and Constant shoulder scores was performed in 74 patients (93%). RESULTS: Preoperatively, the mean UCLA score was 19 (SD 3) in the Outpatient Group, and 19 (SD 3) in the Hospitalized Group. Respectively, the mean Constant scores were 62 (SD 10) and 60 (SD 11). At the follow-up, the mean UCLA score was 32 (SD 4) in the Outpatient Group, and 32 (SD 3) in the Hospitalized Group, which both indicated good clinical outcome. Respectively, the mean Constant scores were 95 (SD 7) and 92 (SD 11), which both indicated excellent clinical outcome. At the follow-up, the UCLA and the Constant shoulder scores were significantly bet-ter than preoperatively in both groups (p < 0.01, p < 0.01), although no differences were found between the groups.The duration of the sick leaves and ability to return to work were similar in both groups. Also, the isometric elevation strengths of the operated shoulders were equally good in both groups. CONCLUSIONS: According to this study, the results of arthroscopic subacromial decompression were equally good whether the patient was treated as an outpatient way or by staying over-night in hospital after surgery. The results were significantly better at follow-up than preoperatively in both groups. Key words: Shoulder pain; subacromial impingement; arthroscopic subacromial decompression; outpatient unit; hospitalized patient; clinical result.

Indentation diagnostics of cartilage degeneration.

OBJECTIVE: Mechanical indentation and ultrasound (US) indentation instruments have been introduced for quantitative assessment of cartilage properties in vivo. In this study, we compared capabilities of these instruments to determine properties of healthy and spontaneously degenerated human patellar cartilage in situ and to diagnose the early stages of osteoarthritis (OA). DESIGN: Six anatomical sites were localized from human patellae (N=14). By determining the force by which the tissue resists constant deformation (F(IND)), a mechanical indentation instrument was used to measure the compressive dynamic stiffness of cartilage. Further, the dynamic modulus (E(US)) and the US reflection coefficient of cartilage surface (R(US)) were measured with an US indentation instrument. For reference, Young's modulus and dynamic modulus were determined from cartilage disks using unconfined compression geometry. Proteoglycan and collagen contents of samples were analyzed microscopically. The samples were divided into three categories (healthy, early degeneration, and advanced degeneration) based on the Osteoarthritis Research Society International (OARSI) OA-grading. RESULTS: Parameters R(US), E(US) and F(IND) were significantly associated with the histological, compositional and mechanical properties of cartilage (|r|=0.28-0.72, n=73-75, P<0.05). Particularly, R(US) was able to discern degeneration of the samples with high sensitivity (0.77) and specificity (0.98). All parameters, except R(US,) showed statistically significant site-dependent variation in healthy cartilage. CONCLUSIONS: US reflection measurement shows potential for diagnostics of early OA as no site-matched reference values are needed. In addition, the high linear correlations between indentation and reference measurements suggest that these arthroscopic indentation instruments can be used for quantitative evaluation of cartilage mechanical properties, e.g., after cartilage repair surgery.

Evaluation of cartilage repair in the distal femur after autologous chondrocyte transplantation using T2 relaxation time and dGEMRIC.

OBJECTIVES: To investigate the potential of combining T2 relaxation time and delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) measurements after autologous chondrocyte transplantation (ACT). MATERIALS AND METHODS: T2 and dGEMRIC maps were measured in the sagittal and coronal directions in 12 patients 10-15 months after ACT surgery. Grafts were assessed for bulk full thickness, superficial and deep tissue T2 and dGEMRIC values, and were compared to control cartilage. RESULTS: All ACT grafts showed filling of the repair area to the level of or above the articular surface. Matrix of the grafts lacked the classical laminar structure and appeared more heterogenous on T2 maps than control cartilage. As compared to control cartilage, ACT grafts showed significantly longer T2 values for bulk tissue as well as for the superficial 50% and deep 50% of tissue except for superficial cartilage in the coronal direction. dGEMRIC assessment in the sagittal and coronal directions did not show a significant difference between bulk, superficial or deep tissue as compared to the control cartilage. Superficial and deep ACT tissue did not differ statistically in terms of their T2 or dGEMRIC values. CONCLUSIONS: These preliminary results suggest that, according to T2 measurements, ACT repair tissue at 10-15 months differs from normal cartilage and probably lacks the preferential collagen arrangement of normal cartilage, while according to dGEMRIC a varying degree of proteoglycan replenishment takes place. Combining these two quantitative magnetic resonance imaging techniques enables a more comprehensive characterization of cartilage repair than before.

Interrelationships between electrical properties and microstructure of human trabecular bone.

Microstructural changes, such as reduction of trabecular thickness and number, are characteristic signs of osteoporosis leading to diminished bone strength. Electrical and dielectric parameters might provide diagnostically valuable information on trabecular bone microstructure not extractable from bone mineral density measurements. In this study, structural properties of human trabecular bone samples (n=26) harvested from the distal femur and proximal tibia were investigated using the computed microtomography (microCT) technique. Quantitative parameters, e.g. structural model index (SMI) or trabecular bone volume fraction (BV/TV), were calculated. In addition, the samples were examined electrically over a wide frequency range (50 Hz-5 MHz) using a two-electrode impedance spectroscopy set-up. Relative permittivity, loss factor, conductivity, phase angle, specific impedance and dissipation factor were determined. Significant linear correlations were obtained between the dissipation factor and BV/TV or SMI (|r| 0.70, p<0.01, n=26). Principal component analyses, conducted on electrical and structural parameters, revealed that the high frequency principal component of the dissipation factor was significantly related to SMI (r=0.72, p<0.01, n=26). The linear combination of high and low frequency relative permittivity predicted 73% of the variation in BV/TV. To conclude, electrical and dielectric parameters of trabecular bone, especially relative permittivity and dissipation factor, were significantly and specifically related to a trabecular microstructure as characterized with microCT. The data gathered in this study constitute a useful basis for theoretical and experimental work towards the development of impedance spectroscopy techniques for detection of bone quality in vitro or in special cases of open surgery.

Quantitative ultrasound imaging of spontaneous repair of porcine cartilage.

OBJECTIVE: Arthroscopy offers qualitative means to evaluate the surface of articular cartilage. However, possible degeneration of the deep cartilage and subchondral bone remains undetected. High frequency ultrasound imaging is an advanced cartilage evaluation method which is conceivable to arthroscopic use and brings diagnostic information also from deeper cartilage and subchondral bone. DESIGN: In this study, we characterized spontaneous repair of porcine cartilage in situ with quantitative 2D-ultrasound imaging. At the age of 7-8 months, a cartilage lesion (diameter 6mm, not penetrating into subchondral bone) was created on the lateral facet of the right femoral trochlea (n=8). The animals were sacrificed 3 months after the surgery. The lesion site, adjacent cartilage and the corresponding control area at the contralateral (left) knee were imaged in situ with 20 MHz ultrasound. Ultrasound reflection coefficients were determined from the cartilage surface (R) and from the cartilage-bone interface (R(bone)). Microtopography of the articular surface was quantified by calculating ultrasound roughness index (URI) parameter from the ultrasonically determined surface profile. RESULTS: Lesion site was spontaneously filled with visually cartilage-like soft tissue with smooth surface. However, ultrasonic images and histological analyses revealed erosion of subchondral bone under the lesion site. Ultrasound reflection (R) at the surface of the spontaneously repaired tissue was significantly lower (-73.5+/-7.6%, P<0.05) than at the surface of intact cartilage. R(bone) was lowest at the lesion site. The surface roughness of spontaneously repaired cartilage was significantly higher than that of the intact tissue (44.0+/-26.0 microm vs 7.5+/-2.3 microm, P<0.05). CONCLUSIONS: Quantitative ultrasound parameters offered diagnostic information revealing impaired structural integrity of the spontaneously repaired porcine cartilage and subchondral bone. These changes are not detectable by traditional arthroscopic means.

Subchondral bone reaction associated with chondral defect and attempted cartilage repair in goats.

Repair of cartilage damage with autologous chondrocyte transplantation (ACT) has become popular in clinical use during the past few years. Although clinical results have mostly been successful, several unanswered questions remain regarding the biological mechanism of the repair process. The aim of this study was to develop a goat model for ACT. The repair was not successful due to the graft delamination, but we characterize the subchondral changes seen after the procedure. A chondral lesion was created in 14 goat knees, operated on 1 month later with ACT, and covered with periosteum or a bioabsorbable poly-L/D-lactide scaffold. After 3 months, only two of the five lesions repaired with ACT showed partly hyaline-like repair tissue, and all lesions (n = 4) with the scaffold failed. Even though the lesions did not extend through the calcified cartilage, the bone volume and collagen organization of bone structure were decreased when assessed by quantitative polarized light microscopy. There was a significant loss of bone matrix and distortion of the trabecular structure of subchondral bone, which extended several millimeters into the bone. The subchondral bone demonstrated strong hyaluronan staining in the bone marrow and cartilaginous areas with signs of endochondral ossification, suggesting structural remodeling of the bone. The goat model used here proved not to be an optimal model for ACT. The changes in subchondral bone may alter the biomechanical properties of the subchondral plate and thus the long-term survival of the repair tissue after ACT.

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.

Site-specific immunostaining for type X collagen in noncalcified articular cartilage of canine stifle knee joint.

Type X collagen is a short-chain collagen that is strongly expressed in hypertrophic chondrocytes. In this study, we used an immunohistochemical technique exploiting a prolonged hyaluronidase unmasking of type X collagen epitopes to show that type X collagen is not restricted to calcified cartilage, but is also present in normal canine noncalcified articular cartilage. A 30 degrees valgus angulation procedure of the right tibia was performed in 15 dogs at the age of 3 months, whereas their nonoperated sister dogs served as controls. Samples were collected 7 and 18 months after the surgery and immunostained for type X collagen. The deposition of type X collagen increased during maturation from age 43 weeks to 91 weeks. In the patella, most of the noncalcified cartilage stained for type X collagen, whereas, in the patellar surface of the femur, it was present mainly in the femoral groove close to cartilage surface. In femoral condyles, the staining localized mostly in the superficial cartilage on the lateral and medial sides, but not in the central weight-bearing area. In tibial condyles, type X collagen was often observed close to the cartilage surface in medial parts of the condyles, although staining could also be seen in the deep zone of the cartilage. Staining for type X collagen appeared strongest at sites where the birefringence of polarized light was lowest, suggesting a colocalization of type X collagen with the collagen fibril arcades in the intermediate zone. No significant difference in type X collagen immunostaining was observed in lesion-free articular cartilage between controls and dogs that underwent a 30 degrees valgus osteotomy. In osteoarthritic lesions, however, there was strong immunostaining for both type X collagen and collagenase-induced collagen cleavage products. The presence of type X collagen in the transitional zone of cartilage in the patella, femoropatellar groove, and in tibial cartilage uncovered by menisci suggests that it may involve a modification of collagen fibril arrangement at the site of collagen fibril arcades, perhaps providing additional support to the collagen network.

Estimation of the Young's modulus of articular cartilage using an arthroscopic indentation instrument and ultrasonic measurement of tissue thickness.

We evaluated whether the use of cartilage thickness measurement would improve the ability of the arthroscopic indentation technique to estimate the intrinsic stiffness of articular cartilage. First, cartilage thickness and ultrasound reflection from the surface of bovine humeral head were registered in situ using a high-frequency ultrasound probe. Subsequently, cartilage was indented in situ at the sites of the ultrasound measurements using arthroscopic instruments with plane-ended and spherical-ended indenters. Finally, full-thickness cartilage disks (n=30) were extracted from the indented sites (thickness=799-1654microm) and the equilibrium Young's modulus was determined with a material testing device in unconfined compression geometry. We applied analytical and numerical indentation models for the theoretical correction of experimental indentation measurements. An aspect-ratio (the ratio of indenter radius to cartilage thickness) correction improved the correlation of the indenter force with the equilibrium Young's modulus from r(2)=0.488 to r(2)=0.642-0.648 (n=30) for the plane-ended indenter (diameter=1.000mm, height=0.300mm) and from r(2)=0.654 to r(2)=0.684-0.692 (n=30) for the spherical-ended indenter (diameter=0.500mm, height=0.100mm), depending on the indentation model used for the correction. The linear correlation between the ultrasound reflection and the Young's modulus was r(2)=0.400 (n=30). These results suggest that with large indenters, knowledge of the cartilage thickness improves the reliability of the indentation measurements, especially in pathological situations where cartilage thickness may be significantly lower than normal. Ultrasound measurements also provide diagnostically important information about cartilage thickness as well as knowledge of the integrity of the superficial zone of cartilage.

Optimization of the arthroscopic indentation instrument for the measurement of thin cartilage stiffness.

Structural alterations associated with early, mostly reversible, degeneration of articular cartilage induce tissue softening, generally preceding fibrillation and, thus, visible changes of the cartilage surface. We have already developed an indentation instrument for measuring arthroscopic stiffness of cartilage with typical thickness >2 mm. The aim of this study was to extend the applicability of the instrument for the measurement of thin (<2 mm) cartilage stiffness. Variations in cartilage thickness, which will not be known during arthroscopy, can nonetheless affect the indentation measurement, and therefore optimization of the indenter dimensions is necessary. First, we used theoretical and finite element models to compare plane-ended and spherical-ended indenters and, then, altered the dimensions to determine the optimal indenter for thin cartilage measurements. Finally, we experimentally validated the optimized indenter using bovine humeral head cartilage. Reference unconfined compression measurements were carried out with a material testing device. The spherical-ended indenter was more insensitive to the alterations in cartilage thickness (20% versus 39% in the thickness range 1.5-5 mm) than the plane-ended indenter. For thin cartilage, the optimal dimensions for the spherical-ended indenter were 0.5 mm for diameter and 0.1 mm for height. The experimental stiffness measurements with this indenter correlated well with the reference measurements (r = 0.811, n = 31, p < 0.0001) in the cartilage thickness range 0.7-1.8 mm. We conclude that the optimized indenter is reliable and well suited for the measurement of thin cartilage stiffness.

Experimental validation of arthroscopic cartilage stiffness measurement using enzymatically degraded cartilage samples.

In order to evaluate the ability of the arthroscopic indentation instrument, originally developed for the measurement of cartilage stiffness during arthroscopy, to detect cartilage degeneration, we compared changes in the stiffness with the structural and constitutional alterations induced by enzymes on the tissue in vitro. The culturing of osteochondral plugs on Petri dishes was initiated in Minimum Essential Medium with Earle's salts and the baseline stiffness was measured. Then, the experimental specimens were digested using 50 microg ml(-1) trypsin for 24 h, 0.1 U ml(-1) chondroitinase ABC or 30 U ml(-1) purified collagenase (type VII) for 24 h or 48 h (n = 8-15 per group). The control specimens were incubated in the medium. After the enzyme digestion, the end-point stiffness was measured and the specimens for the microscopic analyses were processed. The proteoglycan (PG) distribution was analysed using quantitative microspectrophotometry and the quantitative evaluation of the collagen network was made using a computer-based polarized light microscopy analysis. Decrease (p < 0.05) of cartilage stiffness was found after 24 h trypsin (36%) and 48 h chondroitinase ABC (24%) digestion corresponding to a decrease (p < 0.01) of up to 80% and up to 30% in the PG content respectively. Decrease of the superficial zone collagen content or arrangement (78%, p < 0.001) after 48 h collagenase digestion also induced a decrease (30%, p < 0.001) in cartilage stiffness. We conclude that our instrument is capable of detecting early structural and compositional changes related to cartilage degeneration.

Markers of cartilage and synovial metabolism in joint fluid and serum of patients with chondromalacia of the patella.

OBJECTIVE: To further our understanding of the pathogenesis of chondromalacia of the patella (CM), we have studied the release into knee joint fluid and serum, obtained from patients with CM, of molecules associated with the metabolism of joint cartilage matrix and synovium. METHODS: Interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), stromelysin-1 (MMP-3), interstitial collagenase (MMP-1), tissue inhibitor for metalloproteinases-1 (TIMP-1), phospholipase activity A2 (PLA2), hyaluronan (HA), aggrecan fragments (AGN) and antigenic keratan sulfate (KS) were quantified in knee joint lavage fluid from 96 patients with CM; KS and HA also was measured in serum. Chondromalacia was graded on a scale of I to IV according to Outerbridge (1961). The histopathology of the synovial membrane close to the patellofemoral joint was evaluated. Control samples were obtained from nine patients with knee pain presenting with arthroscopically normal knee joints. RESULTS: The concentrations of MMP-3, MMP-1 and TIMP-1 proteins in joint lavage fluid were increased in advanced (grade IV) CM, compared with controls. Levels of MMP-1 in lavage fluid correlated with the severity of CM (r = 0.38, P < 0.01) and MMP-1 and MMP-3 concentrations correlated with each other (r = 0.45, P < 0.001). TIMP-1 was elevated in grade IV CM compared with grades II and III CM (P < 0.02, P < 0.01). Interleukins (IL-1 alpha, IL-1 beta and IL-6) showed no significant change in CM. The lavage fluid level of PLA2 increased with the severity of CM (r = 0.40, P < 0.001). Serum KS was higher in CM IV than in controls (P = 0.05), while lavage fluid KS concentration was elevated in CM I (P = 0.04). There were no differences in the lavage fluid levels of AGN and HA between the different study groups. Synovium showed slight or moderate histological signs of inflammation in 9% of CM patients. CONCLUSION: The changes in the release and activity of these marker molecules from serum and synovial fluid may reflect changes in the metabolism of articular cartilage and synovium in CM, that are consistent with those observed in early-stage tibiofemoral cartilage changes in OA.

Collagen crosslinks in chondromalacia of the patella.

The aim of the study was to determine collagen concentration and collagen crosslinks in cartilage samples from chondromalacia of the patella. To study the extracellular matrix alterations associated to chondromalacia, we determined the concentration of collagen (hydroxyproline) and its hydroxylysylpyridinoline and lysylpyridinoline crosslinks from chondromalacia foci of the patellae in 12 patients and 7 controls from apparently normal cadavers. The structure of the collagen network in 8 samples of grades II-IV chondromalacia was examined under polarized light microscopy. The full-thickness cartilage samples taken with a surgical knife from chondromalacia lesions did not show changes in collagen, hydroxylysylpyridinoline and lysylpyridinoline concentration as compared with the controls. Polarized light microscopy showed decreased birefringence in the superficial cartilage of chondromalacia lesions, indicating disorganization or disappearance of collagen fibers in this zone. It is concluded that the collagen network shows gradual disorganization with the severity of chondromalacia lesion of the patella without changes in the concentration or crosslinks of collagen.

Slowly progressive osteoarthritis after tibial valgus osteotomy in young beagle dogs.

A slowly progressive osteoarthritis model in the skeletally immature canine knee joint is described. Forty-four young female beagle dogs were chosen as experimental animals. In 15 dogs, a 30 degrees valgus angulation of the right tibia was created by operation. Fourteen dogs underwent sham operation. Fifteen dogs served as control subjects. Alterations in the knee joints were evaluated macroscopically and histologically 7 and 18 months after operation. Seven months after surgery, two of seven beagles that had valgus osteotomy had a lesion with discoloration of cartilage in the medial condyle of the femur. Eighteen months after operation, five of the eight dogs that had valgus osteotomy showed fibrillation of the femoral and tibial cartilages. Mankin's scoring of the knee joint cartilages indicated statistically significant changes as compared with control subjects 7 and 18 months after surgery. Biomechanical analysis revealed shift of the mechanical axis toward the lateral compartment of the knee by the valgus osteotomy, patellofemoral malalignment, and inclination of the tibiofemoral joint line. These biomechanical alterations brought about the most severe cartilage lesions to the medial condyle of the femur and the patellofemoral joint. Cartilage fibrillation took more than 7 months to develop. Thus, this model offers a slowly progressive, well standardized, and reproducible method for the study of early changes of osteoarthritis in young beagle dogs.

Proteoglycan depletion and size reduction in lesions of early grade chondromalacia of the patella.

OBJECTIVE: To determine the content and molecular size of proteoglycans (PGs) in patellar chondromalacia (CM) and control cartilages as a first step in investigating the role of matrix alterations in the pathogenesis of this disease. METHODS: Chondromalacia tissue from 10 patients was removed with a surgical knife. Using identical techniques, apparently healthy cartilage of the same site was obtained from 10 age matched cadavers (mean age 31 years in both groups). Additional pathological cartilage was collected from 67 patients with grades II-IV CM (classified according to Outerbridge) using a motorised shaver under arthroscopic control. The shaved cartilage chips were collected with a dense net from the irrigation fluid of the shaver. The content of tissue PGs was determined by Safranin O precipitation or uronic acid content, and the molecular size by mobility on agarose gel electrophoresis. RESULTS: The mean PG content of the CM tissue samples with a knife was dramatically reduced, being only 15% of that in controls. The cartilage chips collected from shaving operations of grades II, III, and IV CM showed a decreasing PG content: 9%, 5%, and 1% of controls, respectively. Electrophoretic analysis of PGs extracted with guanidium chloride from the shaved tissue samples suggested a significantly reduced size of aggrecans in the mild (grade II) lesions. CONCLUSION: These data show that there is already a dramatic and progressive depletion of PGs in CM grade II lesions. This explains the softening of cartilage, a typical finding in the arthroscopic examination of CM. The PG size reduction observed in grade II implicates proteolytic attack as a factor in the pathogenesis of CM.