The Matrilin-3 T298M mutation predisposes for post-traumatic osteoarthritis in a knock-in mouse model.

OBJECTIVE: The human matrilin-3 T303M (in mouse T298M) mutation has been proposed to predispose for osteoarthritis, but due to the lack of an appropriate animal model this hypothesis could not be tested. This study was carried out to identify pathogenic mechanisms in a transgenic mouse line by which the mutation might contribute to disease development. METHODS: A mouse line carrying the T298M point mutation in the Matn3 locus was generated and features of skeletal development in ageing animals were characterized by immunohistology, micro computed tomography, transmission electron microscopy and atomic force microscopy. The effect of transgenic matrilin-3 was also studied after surgically induced osteoarthritis. RESULTS: The matrilin-3 T298M mutation influences endochondral ossification and leads to larger cartilage collagen fibril diameters. This in turn leads to an increased compressive stiffness of the articular cartilage, which, upon challenge, aggravates osteoarthritis development. CONCLUSIONS: The mouse matrilin-3 T298M mutation causes a predisposition for post-traumatic osteoarthritis and the corresponding knock-in mouse line therefore represents a valid model for investigating the pathogenic mechanisms involved in osteoarthritis development.

Collagen IX deficiency leads to premature vascularization and ossification of murine femoral heads through an imbalance of pro- and antiangiogenic factors.

OBJECTIVE: The vascular invasion of cartilage is an essential process in the endochondral ossification of long bones. In contrast, vascularization of articular cartilage constitutes a pathological mechanism in the development of osteoarthritis. Polymorphisms of Col9a1 have been described as risk factors for hip osteoarthritis (OA) and the loss of collagen IX is known to lead to premature OA of the hip joint in mice but the underlying mechanism is so far unknown. DESIGN: To understand the contribution of collagen IX to OA development in the hip joint, we analyzed the early development of murine Col9a1-/- femoral heads between newborn stage and 16 weeks of age. RESULTS: We found significantly accelerated ossification of the femoral heads in the absence of collagen IX as well as premature vascular and osteoclast invasion, even though hypertrophic differentiation was delayed. The loss of collagen IX led to anatomically altered femoral heads lacking the epiphyseal tubercle. Interestingly, this region was found to contain highest levels of the antiangiogenic protein thrombospondin-1 (TSP-1). Hence, TSP-1 levels were strongly reduced in the Col9a1-/- femoral heads. In addition, antiangiogenic matrilin-1 was found to be decreased, while proangiogenic active MMP-9 levels were increased in the collagen IX deficient mice compared to wildtype controls. CONCLUSION: We conclude that collagen IX protects against premature vascularization and cartilage to bone transition in femoral heads by increasing the levels of antiangiogenic TSP-1 and matrilin-1 and decreasing the levels of proangiogenic active MMP-9.

Effect of different running modes on the morphological, biochemical, and mechanical properties of articular cartilage.

Mechanical loading plays an important role not solely in cartilage development, but also in cartilage degeneration. Its adaptation behavior to mechanical loading has not been clearly delineated. The aim of the study was to examine the effect of different running modes (with different muscle contraction types) on morphological, biochemical, and mechanical properties of articular cartilage in the knee of growing rats. Thirty-six female Sprague-Dawley rats were randomly assigned into a nonactive age-matched control (AMC), level (LEVEL), and 20° downhill (DOWN) running group (n = 12 each). Running groups were trained on a treadmill for 30 min/day, 5 days/week for 6 weeks. Immunohistochemical staining and analysis of expression for collagen II, collagen IX, cartilage oligomeric matrix protein (COMP), and matrilin-3, histomorphometry of femoral cartilage height and femoral COMP staining height, and indentation testing of tibial articular cartilage were performed. Rats subjected to downhill running showed a significantly (P = 0.015) higher COMP staining height and a tendentially (P = 0.084) higher cartilage height in the high-weight bearing area of femoral articular cartilage. Cartilage thickness, mechanical properties, and expression of cartilage network proteins in tibial cartilage remained unaffected by different running modes. Our data suggest that joint loading induced by eccentric muscle contractions during downhill running may lead to a site-specific adaptation.

Deformational behaviour of knee cartilage and changes in serum cartilage oligomeric matrix protein (COMP) after running and drop landing.

OBJECTIVE: To investigate (1) the effect of running and drop landing interventions on knee cartilage deformation and serum cartilage oligomeric matrix protein (COMP) concentration and (2) if the changes in cartilage volume correlate with the changes in serum COMP level. METHODS: Knee joint cartilage volume and thickness were determined using magnetic resonance imaging (MRI) as well as COMP concentration from serum samples before and after in vivo loading of 14 healthy adults (seven male and seven female). Participants performed different loading interventions of 30 min duration on three different days: (1) 100 vertical drop landings from a 73 cm high platform, (2) running at a velocity of 2.2m/s (3.96 km), and (3) resting on a chair. Blood samples were taken immediately before, immediately after and 0.5h, 1h, 2h and 3h post intervention. Pre- and post-loading coronal and axial gradient echo MR images with fat suppression were used to determine the patellar, tibial and femoral cartilage deformation. RESULTS: Serum COMP levels increased immediately after the running (+30.7%, pre: 7.3U/l, 95% confidence interval (CI): 5.6, 8.9, post: 9.1U/l, 95% CI: 7.2, 11.0, P=0.001) and after drop landing intervention (+32.3%, pre: 6.8U/l, 95% CI: 5.3, 8.4; post: 8.9U/l, 95% CI: 6.8, 10.9, P=0.001). Cartilage deformation was more pronounced after running compared to drop landing intervention, with being significant (volume: P=0.002 and thickness: P=0.001) only in the lateral tibia. We found a significant correlation (r(2)=0.599, P=0.001) between changes in serum COMP (%) and in cartilage volume (%) after the drop landing intervention, but not after running. CONCLUSIONS: In vivo exercise interventions differentially regulate serum COMP concentrations and knee cartilage deformations. The relation between changes in COMP and in cartilage volume seems to depend on both mechanical and biochemical factors.

Different mechanical loading protocols influence serum cartilage oligomeric matrix protein levels in young healthy humans.

The purpose of the study was to investigate whether a relationship between the loading mode of physical activity and serum cartilage oligomeric matrix protein (COMP) concentration exists and whether the lymphatic system contributes to COMP release into the serum. Serum COMP levels were determined in healthy male subjects before, after and at 18 further time points within 7 h at four separate experimental days with four different loading interventions. The loading intervention included high impact running exercise, slow but deep knee bends, and lymphatic drainage of 30 min duration, respectively, and a resting protocol. The serum COMP levels were measured using a commercially available quantitative enzyme-linked immunosorbent assay. An increase (p < 0.001) in serum COMP concentration was detected immediately after 30 min running exercise. Slow but deep knee bends did not cause any significant changes in serum COMP levels. Lymphatic drainage also had no effect on the serum COMP concentration. After 30 min of complete rest the serum COMP level was significantly (p = 0.008) reduced. The elevation of COMP serum concentration seems to depend on the loading mode of the physical activity and to reflect the extrusion of COMP fragments from the impact loaded articular cartilage or synovial fluid.

The chondroprotective effect of selective COX-2 inhibition in osteoarthritis: ex vivo evaluation of human cartilage tissue after in vivo treatment.

OBJECTIVE: Recent in vitro studies showed that celecoxib, a selective cyclooxygenase (COX)-2 inhibitor, protects human osteoarthritic cartilage tissue from degeneration. The objective was to substantiate these beneficial effects in an in vivo (clinical) study with celecoxib treatment of patients with severe knee osteoarthritis (OA) and subsequent evaluation of cartilage tissue ex vivo. METHODS: Patients with knee OA were treated 4 weeks prior to total knee replacement surgery with either celecoxib 200mg b.d., indomethacin 50mg b.d., or received no treatment. During surgery cartilage and synovium were collected and analyzed in detail ex vivo. RESULTS: When compared to non-treated patients, patients treated with celecoxib showed significant beneficial effects on proteoglycan synthesis, -release, and -content, confirming the in vitro data. In the indomethacin group, no significant differences were found compared to the control group. On the contrary, a tendency towards a lower content and lower synthesis rate was found. In the treated groups prostaglandin-E(2) levels were lower than in the control group, indicating COX-2 inhibition. Ex vivo release of interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha by synovial tissue was decreased by treatment with celecoxib, whereas in the indomethacin group only IL-1 beta release was decreased. CONCLUSION: Using this novel approach we were able to demonstrate an in vivo generated chondrobeneficial effect of celecoxib in patients with end stage knee OA.

Stability changes after cryosurgery in long tubular bones in correlation to histological results: an animal trial.

STUDY QUESTION: Pathologic bone fractures in cryosurgery of bone tumors have been described in literature. This study utilizing a sheep model should prove the possible reduction of potential fracture while using a new miniature cryoprobe minimizing tissue damage and providing accurate control of the ablation process. Furthermore, postoperative histological changes should be investigated and the results correlated with the stability trials. METHODS: In 24 sheep, ablation of the femur and the tibial bone on one side was carried out. Ablation of the right femur was limited to an area of 2 cm(2) with single cortical bone, whereas at the left tibia the whole proximal tibial plateau was included. The other side served as a control entity without cryoablation. After a period of 2, 4, and 6 months postoperative investigation of bending resistance of the femoral bone and of compression resistance of the tibial bone as well as histological findings were done in eight animals each. RESULTS: After 2 months there was a significant difference (P < 0.05) regarding compression resistance between the treated and the contralateral tibia, whereas the bending resistance in the treated femur was slightly lower than on the contralateral side. After 4 and 6 months the cryo-treated part showed a tendency towards weakness. Histological findings showed bone necrosis with slight beginning repair after 2 months. Four and six months later, bone necrosis still existed with increasing development of woven bone and conversion into lamellar bone. DISCUSSION: A thorough control of the freezing process and the low iatrogenous weakening of the bone due to placing the probe when modern miniature cryoprobes are used can minimize the risk of pathological postoperative fractures. However, at least 2 months after operation there is histological proof of bone healing with appropriate reduction of bone stability, which should be considered for the clinical application of this new technique.

[Changes in stability after cryosurgical treatment of long tubular bones. An animal experiment study]. / Stabilitätsveränderungen nach kryochirurgischer Behandlung an langen Röhrenknochen. Eine tierexperimentelle Studie.

The incidence of spontaneous fractures after cryosurgical treatment is described in the literature. The purpose of this study in the sheep model was to analyze the possibility of minimizing the potential risk of bone failure using a new miniature cryoprobe with minimal tissue traumatism and exact control of the ablation. In each of 24 sheep ablations at the right femur and left tibia were performed by drilling. The ablation at the femur was restricted to an area of 2 cm(2) of only one cortical bone, whereas at the proximal tibia the whole tibial plateau was included. The opposite side, which was treated with analog drillings without cryoablation, served as control. The ultimate bending strength of the femur and the ultimate compression strength of the tibia were examined 2, 4, and 6 months after the operation. After 2 months there was a significant difference ( p<0.05) in the ultimate compression strength between the treated and untreated tibiae, whereas the ultimate bending strength of the treated femora tended to be lower. After 4 and 6 months the side treated with cryosurgery was only marginally weaker than the untreated side. Spontaneous fractures were not observed during the whole experimental period. The good controllability of the freezing procedure and the low iatrogenic weakening of the bone using a modern miniature cryoprobe minimizes the risk of pathological postoperative fractures. After ablation of larger bone sections, the treated extremity should be partially unloaded or managed by osteosynthesis for at least 3 months.

[Sonographically guided core needle biopsy of the breast: technique, accuracy and indications]. / Ultraschallgezielte Stanzbiopsie der Mamma: Technik, Ergebnisse, Indikationen.

PURPOSE: The purpose of this retrospective analysis was to assess the diagnostic accuracy and complication rate of sonographically guided core needle biopsy in palpable breast masses, mammographically detected nonpalpable lesions, and sonographically detected clinically and mammographically occult lesions. PATIENTS AND METHODS: Sonographically guided core needle biopsy was performed in 590 lesions in 572 patients, by using an automated biopsy gun with a 14-gauge large core needle and a coaxial system. Core needle biopsy results were compared with surgical biopsy in 265 cases. 325 lesions with benign histologic diagnoses were followed up for at least 18 months. RESULTS: 234 carcinomas and 356 benign abnormalities were found in the 572 patients. Core needle biopsy reached a sensitivity of 98.7% at a specificity of 99.7%. Underestimation rates for lesions initially diagnosed as DCIS and for lesions initially diagnosed as ADH were 3/10 and 6/14, respectively. Of three false-negative results, two were immediately recognized, and one was identified at follow-up. Serious bleeding occurred in one patient (0.2% complication rate). CONCLUSIONS: This report confirms that sonographically guided large core needle biopsy is a safe, reliable and cost-effective method for the assessment of both palpable and nonpalpable, mammographically and sonographically detected breast abnormalities.

Clinically and mammographically occult breast lesions: detection and classification with high-resolution sonography.

With recent significant advances in ultrasound technology, the potential of high-resolution sonography to improve the sensitivity of cancer diagnosis in women with dense breasts has become a matter of interest for breast imagers. To determine how often physician-performed high-resolution sonography can detect nonpalpable breast cancers that are not revealed by mammography, 8,970 women with breast density grades 2 through 4 underwent high-resolution sonography as an adjunct to mammography. All sonographically detected, clinically and mammographically occult breast lesions that were not simple cysts were prospectively classified into benign, indeterminate, or malignant categories. Diagnoses were confirmed by ultrasound-guided fine-needle aspiration, core-needle biopsy, or surgical biopsy. In 8,103 women with normal findings at mammography and physical examination, 32 cancers and 330 benign lesions were detected in 273 patients with sonography only. Eight additional cancers were found in 867 patients with a malignant (n = 5) or a benign (n = 3) palpable or mammographically detected index lesion. The overall prevalence of cancers detected with screening sonography was 0.41%, and the proportion of sonographically detected cancers to the total number of nonpalpable cancers was 22%. The mean size of invasive cancers detected only by sonography was 9.1 mm, and was not statistically different from the mean size of invasive cancers detected by mammography. The sensitivity of prospective sonographic classification for malignancy was 100%, and the specificity was 31%. In conclusion, the use of high-resolution sonography as an adjunct to mammography in women with dense breasts may lead to detection of a significant number of otherwise occult cancers that are no different in size from nonpalpable mammographically detected cancers. Prospective classification of these lesions based on sonographic characteristics resulted in an acceptable benign-to-malignant biopsy rate of 6.3:1.