Comparison of cartilage destruction between infectious and adjuvant arthritis

Current Variation in Joint Aspiration Practice for the Evaluation of Pediatric Septic Arthritis

Pediatric septic arthritis (SA) is a condition that can be associated with significant morbidity. Although previous research has been on predictive care pathways, scrutiny of the literature continues to reveal wide differences in the patient evaluation and management. The purpose of this study was to define the differences in joint aspiration for the evaluation of pediatric SA across pediatric tertiary care institutions in the United States.

An Algorithmic Approach to the Suspected Septic Wrist

An acutely painful, erythematous wrist can be due to a variety of pathologic processes, including crystalline arthropathy, infection, trauma, osteoarthritis, and systemic disease. The broad differential diagnosis of the inflamed wrist and nonspecific clinical findings make accurate diagnosis challenging. There is no published clinical or laboratory criterion that reliably differentiates septic wrist arthritis from a sterile inflammatory arthropathy. For septic joint patients, long-term results are notably poorer in patients with a delay in treatment, therefore establishing evidenced-based guidelines deserves attention.After a comprehensive literature review, we present evidenced-based guidelines and an algorithm for the management of the patient with an acutely inflamed wrist concerning for septic arthritis.For determining a diagnosis, systemic blood laboratory results are extremely variable and unreliable. Despite the attention given to the diagnostic potential of synovial fluid tests, the literature consistently demonstrates that diagnostic certainty cannot always be ascertained at the time of presentation based on aspiration fluid samples. Additionally, the investigative work does not necessarily end at the discovery of crystals since concomitant infection is a rare but well reported entity.Relative to larger joints, the wrist is far less likely to be infected and is easier to drain of debris, and therefore the empiric management of an inflamed wrist joint should reflect these differences. For treatment of the suspected or confirmed septic wrist, prompt initiation with appropriate antibiotics and drainage of joint purulence is critical to rapid recovery. However, the best strategy to clear the joint space of infectious material is controversial. Although the traditional standard of care is open drainage of a septic joint, a growing body of literature supports that for a septic wrist joint, a less invasive approach with serial aspiration can be equally efficacious with reduced morbidity and quicker recovery. If the wrist fails to improve with daily aspirations, then arthroscopy or open washout is needed.For patients with suspected wrist joint infection or crystalline arthropathy with probable concomitant infection, a reasonable approach is admission for systemic antibiotics and daily arthrocentesis. If the wrist fails to improve or worsens, then surgical treatment may be pursued. This treatment strategy could potentially avoid the morbidity of surgery while ensuring that no septic wrist goes untreated.

Rapid in situ chondrocyte death induced by Staphylococcus aureus toxins in a bovine cartilage explant model of septic arthritis

OBJECTIVE

To assess in situ chondrocyte viability following exposure to a laboratory strain and clinical isolates of Staphylococcus aureus.

METHODS

Bovine cartilage explants were cultured in the presence of S. aureus 8325-4 (laboratory strain), clinical S. aureus isolates or non-infected culture medium of pH values 7.4, 6.4 and 5.4. All clinical isolates were isolated from the joint aspirates of patients presenting with S. aureus-induced septic arthritis (SA). At designated time points, in situ chondrocyte viability was assessed within defined regions-of-interest in the axial and coronal plane following live- and dead-cell image acquisition using the fluorescent probes 5-chloromethylfluorescein diacetate (CMFDA) and propidium iodide (PI), respectively, and confocal laser-scanning microscopy (CLSM). Cartilage water content, following S. aureus 8325-4 exposure, was obtained by measuring cartilage wet and dry weights.

RESULTS

S. aureus 8325-4 and clinical S. aureus isolates rapidly reduced in situ chondrocyte viability (>45% chondrocyte death at 40 h). The increased acidity, observed during bacterial culture, had a minimal effect on chondrocyte viability. Chondrocyte death commenced within the superficial zone (SZ) and rapidly progressed to the deep zone (DZ). Simultaneous exposure of SZ and DZ chondrocytes to S. aureus 8325-4 toxins found SZ chondrocytes to be more susceptible to the toxins than DZ chondrocytes. Cartilage water content was not significantly altered compared to non-infected controls.

CONCLUSIONS

Toxins released by S. aureus have a rapid and fatal action on in situ chondrocytes in this experimental model of SA. These data advocate the prompt and thorough removal of bacteria and their toxins during the treatment of SA.

Medical vs surgical treatment for the native joint in septic arthritis: a 6-year, single UK academic centre experience

OBJECTIVE

Medical treatment (serial closed-needle aspiration) and surgical treatment (arthroscopy/arthrotomy combined with joint washout) are well-recognized methods to treat septic arthritis (SA) of native joints. We compared the outcome of proven SA based on the method of treatment.

METHODS

We reviewed case notes of adult patients who were admitted to our institution from January 2001 to December 2006 with proven SA (Newman Grade A organism isolated from the joint).

RESULTS

Thirty-two episodes were treated medically and 19 surgically (4 with arthrotomy, 15 with arthroscopy) in the study period. All had mono-articular SA. No significant difference in the age, symptom duration before treatment and duration of intravenous antibiotic therapy was present between the two groups. Medical treatment resulted in complete recovery in more patients (69 vs 53%, P = 0.24) but longer period of hospitalization [median (interquartile range), 16.5 (14-19) vs 15 (11-17), P = 0.34], although the difference between the groups was not significant. More surgically treated patients had deterioration in functional status at the time of discharge from the hospital (29 vs 44%, P = 0.27), but the difference between the groups was not statistically significant. Surgically treated patients required significantly more sessions of physiotherapy (mean +/- S.D., 7 +/- 2 vs 10 +/- 3, P = 0.002). Mortality was similar (one in each group).

CONCLUSION

Results from this study show that for the native joint SA, surgical treatment was not superior to the medical treatment and, therefore, highlight the need for careful case selection for surgical intervention.

Anti-inflammatory effect of antidiabetic thiazolidinediones prevents bone resorption rather than cartilage changes in experimental polyarthritis

Background

Rosiglitazone and pioglitazone are high-affinity peroxisome proliferator-activated receptor (PPAR)-γ agonists with potent anti-diabetic properties and potential anti-inflammatory effects. We compared the ability of a range of oral doses of these thiazolidinediones, including those sufficient to restore insulin sensitization, to inhibit the pathogenesis of adjuvant-induced arthritis (AIA).

Methods

AIA was induced in Lewis rats by a subcutaneous injection of 1 mg of complete Freund's adjuvant. Rats were treated orally for 21 days with pioglitazone 3, 10 or 30 mg/kg/day, rosiglitazone 3 or 10 mg/kg/day, or with vehicle only. The time course of AIA was evaluated by biotelemetry to monitor body temperature and locomotor activity, by clinical score and plethysmographic measurement of hindpaw oedema. At necropsy, RT-PCR analysis was performed on synovium, liver and subcutaneous fat. Changes in cartilage were evaluated by histological examination of ankle joints, radiolabelled sulphate incorporation (proteoglycan synthesis), glycosaminoglycan content (proteoglycan turnover) and aggrecan expression in patellar cartilage. Whole-body bone mineral content was measured by dual-energy X-ray absorptiometry.

Results

The highest doses of rosiglitazone (10 mg/kg/day) or pioglitazone (30 mg/kg/day) were required to reduce fever peaks associated with acute or chronic inflammation, respectively, and to decrease arthritis severity. At these doses, thiazolidinediones reduced synovitis and synovial expression of TNF-α, IL-1β and basic fibroblast growth factor without affecting neovascularization or the expression of vascular endothelial growth factor. Thiazolidinediones failed to prevent cartilage lesions and arthritis-induced inhibition of proteoglycan synthesis, aggrecan mRNA level or glycosaminoglycan content in patellar cartilage, but reduced bone erosions and inflammatory bone loss. A trend towards lower urinary levels of deoxipyridinolin was also noted in arthritic rats treated with thiazolidinediones. Rosiglitazone 10 mg/kg/day or pioglitazone 30 mg/kg/day increased the expression of PPAR-γ and adiponectin in adipose tissue, confirming that they were activating PPAR-γ in inflammatory conditions, although an increase in fat mass percentage was observed for the most anti-arthritic dose.

Conclusion

These data emphasize that higher dosages of thiazolidinediones are required for the treatment of arthritis than for restoring insulin sensitivity but that thiazolidinediones prevent inflammatory bone loss despite exposing animals to increased fatness possibly resulting from excessive activation of PPAR-γ.

Septic arthritis in Western and sub-Saharan African children - a review

This article reviews what is known about the incidence, aetiology, presentation, bacteriology and management of septic arthritis in children. It compares where possible the different presentations and characteristics of this condition in the Western and sub-Saharan African regions.

Daily Needle Aspiration Versus Surgical Lavage for the Treatment of Bacterial Septic Arthritis in Adults

Septic arthritis is a substantial public health problem, accounting for 0.2-0.7% of hospital admissions. However, despite the availability of effective antibiotics, the appropriate approach to adjunctive therapy remains controversial. Although early drainage is essential to minimize the risks of permanent loss of articular function, it is unclear whether the optimal approach involves arthroscopic lavage or daily arthrocentesis; surgeons appear to prefer surgical lavage because their training routinely considers septic arthritis to be a closed-space infection comparable to an abscess, whereas rheumatologists appear to prefer daily arthrocentesis because of its ease and non-invasive nature. There is a paucity of prospective data comparing the two approaches, and the literature is largely retrospective. Herein, we review the available literature concerning drainage of bacterially infected joints, and conclude that in the absence of prospective randomized clinical trials, the best evidence suggests that there is no compelling reason to recommend surgical lavage for the initial management of uncomplicated septic arthritis.

Staphylococcal septic arthritis: antibiotic and nonsteroidal anti-inflammatory drug treatment in a rabbit model

This study evaluated the effects of combining antibiotic therapy with the application of a nonsteroidal anti-inflammatory drug on the degradation of articular cartilage for an animal model of Staphylococcal septic arthritis. Rabbits were infected intra-articularly with Staphylococcus aureus. Antibiotic treatment started 18 hours after infection and continued for 7 days. Treatment with the nonsteroidal anti-inflammatory drug naproxen sodium started 24 hours before infection and continued for either 3 or 7 weeks. The cartilage matrix of uninfected and infected knees was quantified by analysis of glycosaminoglycan and collagen content. Three weeks after infection, the combined treatment of the nonsteroidal anti-inflammatory drug and antibiotics reduced the loss of glycosaminoglycan and collagen from the cartilage of the infected knee by 15 and 30%, respectively, compared with antibiotic treatment alone. Continuing treatment with naproxen sodium for 7 weeks reduced the loss of collagen by 50% when compared with antibiotic treatment alone. The longer period of treatment with naproxen sodium showed little further effect on the loss of glycosaminoglycan than that observed for the 3-week treatment. Treatment with this drug and antibiotics reduced swelling of the knee and levels of prostaglandin E2 in the synovial fluid. The data support the hypothesis that decreasing post-infectious inflammation by adding the drug to a standard antibiotic regimen reduces cartilage damage from Staphylococcal septic arthritis.

Analogues of methotrexate in rheumatoid arthritis. 1. Effects of 10-deazaaminopterin analogues on type II collagen-induced arthritis in mice

Carbonation of the dianions (LDA) of 5-methylthiophene-2-carboxylic, 2-methylpyridine-5-carboxylic, and 3-methylpyridine-6-carboxylic acids provided the respective carboxy heteroarylacetic acids. The crude diacids were directly esterified in MeOH-HCl to afford the diesters. Alkylation of the sodio anions with ethyl iodide yielded the appropriate alpha-ethyl diesters. The anions of the various diester substrates were then alkylated by 2,4-diamino-6-(bromomethyl)-pteridine followed by ester saponification at room temperature to afford the respective 2,4-diamino-4-deoxy-10-carboxy-10-deazapteroic acids. The 10-carboxyl group was readily decarboxylated by heating in DMSO at temperatures of 110-135 degrees C to give the diamino 10-deaza heteropteroic acid intermediates. Coupling with diethyl L-glutamate followed by ester hydrolysis afforded the target aminopterins. The analogues were evaluated for antiinflammatory effect in the mouse type II collagen model. The thiophene analogue of 10-ethyl-10-deazaaminopterin was found to be an effective inhibitor in terms of reduced visual evidence of inflammation and swelling as determined by caliper measurement.

Chondroprotective effect of betamethasone in lapine pyogenic arthritis

The chondroprotective effect of betamethasone was examined to determine if corticosteroids can decrease articular cartilage injury caused by inflammatory exudate in Staphylococcus aureus gonarthritis in rabbits. Three experimental groups of antibiotic-treated rabbits were created, comparing parenteral versus low-dose intraarticular routes of betamethasone administration. Rabbits that received ceftriaxone plus supplemental parenteral betamethasone (group 2) demonstrated significantly less articular cartilage proteoglycan loss than did rabbits treated with antibiotics alone (group 1). Supplemental intraarticular betamethasone (group 3) was somewhat less effective in this regard, possibly reflecting the smaller steroid dosage. This animal study introduces histologic and biochemical evidence that betamethasone, administered early and in conjunction with appropriate systemic antibiotics, may help protect infected articular cartilage from proteolytic degradation. Further study is needed to prove safety and efficacy of corticosteroids before recommending their clinical use in the treatment of septic arthritis.

Group II phospholipase A2 in synovial fluid and serum in acute arthritis

Increased catalytic activity of synovial-type (group II) phospholipase A2 (syn-PLA2), has been associated with cartilage erosions in rheumatoid arthritis and osteoarthritis. The catalytic activity of phospholipase A2 and the concentration of syn-PLA2 were measured in a prospective study in synovial fluid (SF) samples from 66 patients with acute knee joint effusion. The median (range) of the concentration of syn-PLA2 in SF was 210 micrograms/l (80-1480 micrograms/l) in culture-positive septic arthritis, 460 micrograms/l (270-1040 micrograms/l) in reactive arthritis, 780 micrograms/l (120-2710 micrograms/l) in osteoarthritis and 230 micrograms/l (80-1400 micrograms/l) in traumatic joint effusions. High concentrations of syn-PLA2 are found also in SF of patients with arthritides not expected to lead to permanent destruction of cartilage.

Purified staphylococcal culture medium stimulates neutral metalloprotease secretion from human articular cartilage

Human articular cartilage released significantly increased levels of metal-dependent enzymes capable of degrading collagen, casein, and gelatin at a neutral pH following exposure to a sterile, purified fraction of Staphylococcus aureus culture medium. Neutral metalloprotease activity was determined by radiolabeled substrate assays and substrate gel analysis. The enzymes were activated with 4-aminophenylmercuric acetate and were inhibited by 1,10-phenanthroline and ethylenediamine tetraacetic acid. Protein immunoblots demonstrated that type I collagenase and stromelysin (matrix metalloproteinase III) secretion was increased following staphylococcal medium challenge. The profile of enzymatic activity induced by staphylococcal medium was directly comparable to that observed with interleukin-1, which was used as a positive control. The staphylococcal medium had no inherent proteolytic activity. Increased production of the neutral metalloproteases collagenase and stromelysin may significantly contribute to the extensive cartilage destruction noted in staphylococcal septic arthritis.

Septic arthritis. Staphylococcal induction of chondrocyte proteolytic activity

We report herein that cartilage proteolytic activity increased in bovine and rabbit articular cartilage after treatment with a purified staphylococcal culture medium or intraarticular infection with Staphylococcus aureus. Staphylococcal culture medium increased the release of gelatinolytic, collagenolytic, and caseinolytic activity into the medium of isolated chondrocytes or cartilage organ culture. The proteolytic activities were determined in assays using radiolabeled substrate and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Staphylococcal culture medium was proteolytically inactive by both assay techniques. RNA synthesis of isolated chondrocytes was unaffected by staphylococcal culture medium, whereas overall protein synthesis was inhibited by 84%. An analysis of extracts of Staphylococcus aureus-infected rabbit knee cartilage by substrate gels showed increased gelatinolytic and caseinolytic activity compared with extracts of uninfected knee cartilage. Our data suggest that the rapid loss of proteoglycan and persistent degradation of cartilage in staphylococcal septic arthritis is due to the production and activation of chondrocyte proteases.

Antibiotic treatment insufficient for established septic arthritis. Staphylococcus aureus experiments in rabbits

We treated septic arthritis of the knee in 38 rabbits with cloxacillin i.m. once and twice daily combined with probenecid for 7 or 21 days, respectively, or with only cloxacillin i.m. thrice daily for 7 days. The animals were killed weekly in groups up to 5 weeks after inoculation. Aspirated cultures obtained after 4 days of treatment were always negative. Histologic specimens revealed progressive joint destruction, but at a slower rate after frequent treatment independent of the period. We concluded that antibiotic therapy alone could not prevent destruction of articular cartilage once bacterial arthritis was established.

Induction of articular cartilage degradation by recombinant interleukin 1 alpha and 1 beta

The purpose of this study was to compare the effects of human recombinant interleukin 1, alpha and beta, on articular cartilage. The effects of rIL-1 alpha and rIL-1 beta on proteoglycan degradation and synthesis following treatment of bovine articular cartilage in serum-free organ culture were quantified. Purified human IL-1 and both rIL-1 alpha and rIL-1 beta induced a two-fold or greater increase in glycosaminoglycan (GAG) release from cultured articular cartilage. Levels or rIL-1 alpha as low as 15 pM induced increased proteoglycan degradation whereas identical levels of rIL-1 beta did not. Killing of the cartilage cells abolished induced GAG release by all forms of IL-1. Analysis of proteoglycan size following IL-1 treatment showed limited degradation of material released into the culture medium or remaining within cartilage. Both forms of recombinant IL-1 inhibited GAG synthesis when continually present in the culture medium. Actinomycin D and cycloheximide inhibited IL-1 dependent cartilage destruction whereas indomethacin did not.

Transient synovitis of the hip in the child: increased levels of proteoglycan fragments in joint fluid

The levels of proteoglycan antigen were measured in joint aspirates from the hip of children with transient synovitis, septic arthritis, Legg-Calvé-Perthes' disease and congenital and traumatic dislocation. Significantly increased levels were found in children with transient synovitis and septic arthritis as compared with other conditions. We propose that the proteoglycan antigens in the joint fluid were released from the articular cartilage in a partially degraded form as a result of an increased rate of proteolytic degradation. In transient synovitis, the source of proteolytic activity may be chondrocytes activated by factors released by synovial cells. The release of joint proteoglycan may cause a temporary increase in deformability of the hip cartilage of the child that could be an important pathogenetic mechanism in some of the sequelae of these diseases.

Staphylococcal adhesion to collagen in intra-articular sepsis

Ultrastructural studies of the cartilaginous articular surfaces of human and rabbit joints have shown that cartilage is the target substratum for adhesion by Staphylococcus aureus, leading to intra-articular sepsis. Transmission and scanning electron microscope studies demonstrated bacteria in intimate contact with acellular cartilage matrix surfaces, particularly with collagen fibres. Certain strains of Staphylococcus aureus used in these experiments reveal a high binding capacity to collagen that is derived from a cartilage matrix. These studies indicate that the pathogenesis of intra-articular sepsis is based on the ability of certain strains of staphylococci to bind preferentially to a cartilage matrix.

Bacterial arthritis. A staphylococcal proteoglycan-releasing factor

We report the effect of staphylococci on induction of proteoglycan release from cartilage in organ culture and document the presence of a staphylococcal proteoglycan-releasing factor in the bacterial growth medium. Staphylococci cocultured with cartilage increased release of proteoglycan 3-4-fold within 48 hours. Viable cartilage was essential for maximum loss of proteoglycan. Killed bacteria had no effect on proteoglycan release. Four Staphylococcus aureus strains yielded growth media preparations active in proteoglycan release. Analysis of the proteoglycan subunits released from cartilage showed only limited degradation, and glycosaminoglycan chain length was not significantly altered.