Wolfram Neumann

Development of Osteoarthritis in the Knee Joints of Wistar Rats After Strenuous Running Exercise in a Running Wheel by Intracranial Self-Stimulation

The influence of excessive running load on the development of knee osteoarthritis (OA) was investigated in male Wistar rats. Running exercises were performed in a running wheel using intracranial self-stimulation to motivate Wistar rats to run daily distances of 500 m at 5 days/week. Hereby, ten rats ran a distance of 15 km within three weeks while a further ten rats run a total of 30 km within six weeks. Thirteen Wistar rats without running exercises served as controls. Complete knee joint sections of all rats were evaluated histologically using MANKINs grading system with categorization of the findings into non, mild moderate, and severe osteoarthritis. In addition, immunoreactivity of the chondrocytes to MMP-3 as an important cartilage degrading enzyme in OA was assessed by immunostaining with monoclonal MMP-3 IgG antibodies. Histological assessment of the knee joint sections revealed a significant increase in osteoarthritic changes with higher running load. While in rats with 15 km running all but two knee joints showed mild OA, moderate OA was the predominant finding in rats with 30 km running. In contrast, no OA was found in the controls. Immunostaining for MMP-3 revealed a significant increase in immunoreactivity of the chondrocytes to MMP-3 with higher running load, indicating a running load-depending production of this cartilage-degrading enzyme in the course of increasing OA. Compared to 47.4% immunoreactive chondrocytes to MMP-3 in the controls, this ratio rose to 70.4% in rats with 15 km running and even up to 89.9% in rats with 30 km running. In conclusion, in Wistar rats, excessive running load leads to marked, running distance-depending osteoarthritic changes which are caused, at least in part, by an increase in MMP-3 production rising with greater running distance. Within this exercise model of OA, intracranial self-stimulation is an effective method to motivate Wistar rats to extremely excessive running in a running wheel. This model offers a wide range of further approaches to studying different processes of the development of OA.

Strength and motion after hemiarthroplasty in displaced four-fragment fracture of the proximal humerus: 27 patients followed for 1-6 years.

We evaluated 27 patients with shoulder hemiarthroplasty after displaced four-fragment fracture of the proximal humerus after mean 4 (1-6) years. Isometric strength measurements (Kintrex) and threedimensional motion analysis (Elite-System) were performed on the operated and unoperated shoulders. Clinical assessment was based on Constants score and Neers scoring system. The isometric strength of the operated and unoperated sides were 22 (SD 8.6) Nm and 24 (SD 5.9) Nm in abduction and 48 (SD 14) Nm and 65 (SD 21) Nm, respectively in adduction (the latter was statistically significant). Motion analyses at follow-up showed a mean reduction in glenohumeral movement. Increases in acceleration and deceleration of the acromion at the operated side were noted, indicating a change in glenohumeral rhythm during maximal abduction. The Constant score was 45 (SD 15) points with a significant reduction in the range of motion. 15 patients had some degree of heterotopic ossification. On the basis of our findings, the impaired function seems to be caused by reduced glenohumeral mobility rather than muscle strength. We also found a better outcome after early than late hemiarthroplasty.

Gene Transfer of Tissue Inhibitor of Metalloproteinases-3 Reverses the Inhibitory Effects of TNF-α on Fas-Induced Apoptosis in Rheumatoid Arthritis Synovial Fibroblasts

Apart from counteracting matrix metalloproteinases, tissue inhibitor of metalloproteinases-3 (TIMP-3) has proapoptotic properties. These features have been attributed to the inhibition of metalloproteinases involved in the shedding of cell surface receptors such as the TNFR. However, little is known about effects of TIMP-3 in cells that are not susceptible to apoptosis by TNF-α. In this study, we report that gene transfer of TIMP-3 into human rheumatoid arthritis synovial fibroblasts and MRC-5 human fetal lung fibroblasts facilitates apoptosis and completely reverses the apoptosis-inhibiting effects of TNF-α. Although TNF-α inhibits Fas/CD95-induced apoptosis in untransfected and mock-transfected cells, fibroblasts ectopically expressing TIMP-3 are sensitized most strongly to Fas/CD95-mediated cell death by TNF-α. Neither synthetic MMP inhibitors nor glycosylated bioactive TIMP-3 are able to achieve these effects. Gene transfer of TIMP-3 inhibits the TNF-α-induced activation of NF-κB in rheumatoid arthritis synovial fibroblasts and reduces the up-regulation of soluble Fas/CD95 by TNF-α, but has no effects on the cell surface expression of Fas. Collectively, our data demonstrate that intracellularly produced TIMP-3 not only induces apoptosis, but also modulates the apoptosis-inhibiting effects of TNF-α in human rheumatoid arthritis synovial fibroblast-like cells. Thus, our findings may stimulate further studies on the therapeutic potential of gene transfer strategies with TIMP-3.

Osteoclast-independent bone resorption by fibroblast-like cells.

To date, mesenchymal cells have only been associated with bone resorption indirectly, and it has been hypothesized that the degradation of bone is associated exclusively with specific functions of osteoclasts. Here we show, in aseptic prosthesis loosening, that aggressive fibroblasts at the bone surface actively contribute to bone resorption and that this is independent of osteoclasts. In two separate models (a severe combined immunodeficient mouse coimplantation model and a dentin pit formation assay), these cells produce signs of bone resorption that are similar to those in early osteoclastic resorption. In an animal model of aseptic prosthesis loosening (i.e. intracranially self-stimulated rats), it is shown that these fibroblasts acquire their ability to degrade bone early on in their differentiation. Upon stimulation, such fibroblasts readily release acidic components that lower the pH of their pericellular milieu. Through the use of specific inhibitors, pericellular acidification is shown to involve the action of vacuolar type ATPases. Although fibroblasts, as mesenchymal derived cells, are thought to be incapable of resorbing bone, the present study provides the first evidence to challenge this widely held belief. It is demonstrated that fibroblast-like cells, under pathological conditions, may not only enhance but also actively contribute to bone resorption. These cells should therefore be considered novel therapeutic targets in the treatment of bone destructive disorders.

Development and characteristics of a synovial-like interface membrane around cemented tibial hemiarthroplasties in a novel rat model of aseptic prosthesis loosening

OBJECTIVE Aseptic prosthesis loosening (APL) is related to the formation and aggressive growth of a synovial-like interface membrane (SLIM) between prosthesis and bone. However, investigation of the early phases of SLIM development in humans presents major difficulties. This study was undertaken to develop and characterize the usefulness of a novel animal model of APL that is based on an established model of defined exercise in a running wheel by Wistar rats that have been subjected to intracranial self-stimulation (ICSS). METHODS Cemented tibial hemiarthroplasties were implanted into the left knees of 7 male Wistar rats. After 2 weeks, exercise in a running wheel was started in all rats, with a running-load of 2 hours/day for 5 days/week. Six months postoperatively, the knee joints were removed, decalcified, and embedded in paraffin. Histologic evaluation on hematoxylin and eosin-stained sections was performed to investigate the development of a SLIM and the presence of cement debris particles. To characterize the SLIM on a molecular level and investigate growth-regulating factors, the expression of transforming growth factor beta (TGFbeta) and the anti-apoptotic molecule Bcl-2 was analyzed by immunohistochemistry. RESULTS Although the prostheses appeared mechanically stable after 6 months, the development of SLIM with areas of bone resorption was seen in all samples. Resembling human SLIM, these membranes consisted of loose fibrous tissue, with cement debris particles located particularly at sites originally attached to the prostheses. Immunohistochemistry studies revealed the expression of TGFbeta and Bcl-2 in all specimens. Interestingly, staining for TGFbeta and Bcl-2 was restricted to areas where the SLIM were attached to bone. In contrast, there was only negligible expression of both proteins at sites adjacent to the prostheses. CONCLUSION Our findings demonstrate that the ICSS Wistar rat model constitutes a feasible tool for studying early stages of APL, and specifically the effect of defined running exercise on SLIM formation. The results further suggest that both cellular proliferation, as stimulated by TGFbeta, and altered apoptosis contribute to early stages of SLIM formation. The expression patterns of TGFbeta and Bcl-2 indicate that the growth of the SLIM is initiated and promoted from the bone rather than from the prosthesis.

IMMUNOHISTOCHEMICAL ANALYSIS OF SEVERAL PROTEOLYTIC ENZYMES AS PARAMETERS OF CARTILAGE DEGRADATION

Osteoarthritis is the most common joint disease in humans. It is characterized by a gradual loss of extracellular matrix components of articular cartilage such as collagen and proteoglycan. Presently, however, emphasis is placed on enzymes exerting a strong influence on cartilage degradation. These enzymes include matrix metalloproteinases (MMP), their specific inhibitors (TIMP) and the plasminogen activator/inhibitor system. We applied monoclonal antibodies against MMP-1, -2, -3, -9 and their inhibitors TIMP-1/-2, as well as against urokinase-plasminogen activator u-PA and its inhibitor PAI to investigate their influence on articular cartilage degradation in patients with varusgonarthritis. We examined the cartilage of the lateral and medial compartments of 20 tibia plateaus, which can present with slight and severe cartilage degradations at the same time. In doing so, we tried to show whether or not immunohistological detection of enzymes could serve as a parameter for chondral degradation. The strongest immunoreaction for all enzymes was noted in the superficial layer of articular cartilage both medially and laterally. Between medial and lateral compartments, however, there were striking differences in the immunoreaction intensity of chondrocytes for MMP-1 and -3 as well as for TIMP-1 and u-PA. We noted that in cartilage with more advanced degradation, the immunoreaction for these enzymes was significantly higher in medial than in lateral compartments (p < 0.05). At the immunohistological level, a direct correlation between the grade of cartilage degradation and immunoreaction intensity was found. Our results corroborate the assumption that the expression of certain matrix-degradating enzymes serves as a parameter for the grade of cartilage degradation.

Prospective Study of a Cementless, Mobile-Bearing, Third Generation Total Ankle Prosthesis

Background: The SALTO total ankle prosthesis is a nonce-mented mobile bearing anatomic design characterized by dual Ti-HA coating. This study reviews our results with this prosthesis. Materials and Methods: Between 2001 and 2007, 413 consecutive SALTO prostheses were implanted in our institution in 215 women and 198 men, aged 57.1 ± 11.9 years. At the last visit, 401 implants (47% in the left ankle) were available with a mean followup of 29 (range, 1 to 84) months. Results: Based on the results of the 218 patients with at least 2 years of postoperative followup, the 5-year estimated survivorship, with the primary end-point being implant removal, was 86.6% and ranged from 85.1% in patients with post-traumatic osteoarthritis to 95.6% in those with rheumatoid arthritis. The AOFAS score increased from 50.9 ± 16.8 points preoperatively to 82.2 ± 14 points at followup (mean difference, 31. 1 ± 1.4, 95% confidence interval (C.I.) for the difference, 28. 3 to 33.8, p < 0.001). Visual analog scale for pain decreased from 7.4 ± 1.1 preoperatively to 2.0 ± 2.0 postoperatively (mean difference, −5.4 ± 0.7, 95% C.I. for the difference, −5.6 to −5.2, p < 0.001). Flexion/extension ROM increased from 25.2 ± 14.1 degrees to 33.1 ± 13.6 degrees at the last followup visit (mean difference, 7. 9 ± 0.5 degrees, 95% C.I. for the difference, 4. 3 to 7.2, p < 0.001), while pronation/supination ROM increased from 23.8 ± 13.7 degrees to 25.4 ± 14.5 degrees (mean difference, 1. 6 ± 0.7 degrees, 95% C.I. for the difference, 0. 9 to 2.2, p = 0.005). Conclusion: The SALTO prosthesis provided good clinical and functional results and we believe helps validate the concept of anatomic replacement. Level of Evidence: IV, Retrospective Case Series

Expression of vascular endothelial growth factor during healing of the meniscus in a rabbit model

Our aim was to investigate vascular endothelial growth factor (VEGF) expression after lacerations of a meniscus in a rabbit model. Specimens of meniscus were examined using immunohistochemistry, enzyme-linked immunoassay and the reverse transcription polymerase chain reaction after one, two, five or ten weeks. In the periphery of the meniscus 90% of the lacerations had healed after five and ten weeks, but no healing was observed in the avascular area. Expression of VEGF protein and VEGF mRNA was found in the meniscus of both the operated and the contralateral sites but both were absent in control rabbits which had not undergone operation. The highest expression of VEGF was found in the avascular area after one week (p < 0.001). It then lessened at both the vascular and avascular areas, but still remained greater in comparison with the control meniscus (p < 0.05). Despite greater expression of VEGF, angiogenesis failed at the inner portion. These findings demonstrated the poor healing response in the avascular area which may not be caused by an intrinsic cellular insufficiency to stimulate angiogenesis.

Percutaneous Repair of Acute Achilles Tendon Rupture

Various studies have shown that the operative treatment of a freshly ruptured Achilles tendon is generally considered to be more appropriate than a nonoperative regimen. However, complications in open reconstructions are reported to occur in 11–29%. The method used in this study reduced the risk of complications arising from operation, but simultaneously allowed early postoperative mobilization and functional treatment. It was a percutaneous repair of the Achilles tendon, using two Lengemann extension wires for coadaptation of the ruptured tendon. To fix the rupture site, the authors used a fibrin sealant. The spikes of the wire were hooked in at the fascia of the soleus muscle. Via a big, curved needle, the wire was placed in the distal stumps of the ruptured tendon and guided out laterally and medially above the calcaneus. After blocking the wires distally, the fibrin sealant was applied at the rupture site. The current report describes this method of treatment in 66 patients. The postoperative observation period was 1 year. Sixty-four patients were male and two were female. Their average age was 42 years. The Achilles tendon ruptures occurred during sporting activities and were treated by operation within 22 hours on average. The outcome was very good in 98%. One patient (2%) suffered a rerupture due to trauma. There were no other complications.

p53 Gene mutations in osteosarcomas of low-grade malignancy

Alterations in tumor suppressor gene p53, localized on chromosome 17p13, are considered to play a significant role in the initiation and, to some extent, even in the progression of various malignant tumors. In this respect, investigations on conventional highly malignant osteosarcomas have shown a mutation rate of approximately 20%. However, currently, data on the mutation rate in the group of variant histology osteosarcomas of low-grade malignancy do not exist. Therefore, we investigated a panel of low malignant entities (five low malignant intramedullary osteosarcomas grade 1; one intramedullary osteosarcoma grade 2; eight parosteal osteosarcomas, including one local recurrence grades 1 and 2, and five periosteal osteosarcomas grade 2) with polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis focusing on exons 4 to 8 of the p53 gene followed by direct sequencing. Point mutations were found in one low-grade osteoblastoma-like osteosarcoma and in two periosteal osteosarcomas grade 2 (one missense, one silent, and one nonsense mutation). This mutation rate of 15.7% (3 of 19) is comparable to that determined in highly malignant osteosarcomas. Moreover, the analysis of clinical data did not show any difference in the behavior of tumors with p53 mutations compared with those without. Therefore, we suggest that alterations in p53 gene are an early event in the tumorigenesis of malignant osteoblastic tumors without impact on progression of these tumors.