Diagnostic arthroscopy

Hyaluronic Acid-Based Optical Probe for the Diagnosis of Human Osteoarthritic Cartilage

Osteoarthritis is typically caused by cartilage injury, followed by localized inflammatory responses and tissue deterioration. Early treatment of osteoarthritis is often impossible due to the lack of diagnostic options. Recent studies have supported that different imaging probes can be used for arthritis detection in mice. However, none of these diagnostic tools have been tested on human articular cartilage. To fill this gap, an optical imaging probe was developed to target activated macrophages and the accumulation of imaging probes on tissue was used to assess the severity of human osteoarthritis. Methods: The probe was fabricated using hyaluronic acid (HA) particles conjugated with near-infrared dye and folic acid (FA). The ability of the FA-HA probes to detect activated macrophages and quantify cartilage injury was evaluated using a cell culture model in vitro and human osteoarthritic cartilage explants ex vivo. Results: Our cell study results supported that the FA-HA probes are cell compatible (up to 0.5mg/mL) and can detect activated macrophages in 30 minutes. Using human articular cartilage, we verified the existence of activated macrophages on osteoarthritic cartilage with highly up-regulated expression of folate receptors (~13 folds by comparison with healthy control). In addition, we found that FA-HA probes had higher binding amounts (~3 folds) to osteoarthritic tissue than healthy ones. Histological analyses confirmed that there was a strong linear relationship (R=0.933) between the fluorescent intensity of tissue-associated probe and the extent of folate receptors on osteoarthritic cartilage. Finally, the co-localization of the imaging probe, folate receptors and cartilage degeneration on the tissue sections indicated the extraordinary accuracy and efficiency of this osteoarthritis diagnostic probe. Conclusions: Our results support the probe as an effective diagnostic tool to detect the area and severity of osteoarthritic human articular cartilage.

High-resolution optical coherence tomographic imaging of osteoarthritic cartilage during open knee surgery

This study demonstrates the first real-time imaging in vivo of human cartilage in normal and osteoarthritic knee joints at a resolution of micrometers, using optical coherence tomography (OCT). This recently developed high-resolution imaging technology is analogous to B-mode ultrasound except that it uses infrared light rather than sound. Real-time imaging with 11-microm resolution at four frames per second was performed on six patients using a portable OCT system with a handheld imaging probe during open knee surgery. Tissue registration was achieved by marking sites before imaging, and then histologic processing was performed. Structural changes including cartilage thinning, fissures, and fibrillations were observed at a resolution substantially higher than is achieved with any current clinical imaging technology. The structural features detected with OCT were evident in the corresponding histology. In addition to changes in architectural morphology, changes in the birefringent or the polarization properties of the articular cartilage were observed with OCT, suggesting collagen disorganization, an early indicator of osteoarthritis. Furthermore, this study supports the hypothesis that polarization-sensitive OCT may allow osteoarthritis to be diagnosed before cartilage thinning. This study illustrates that OCT, which can eventually be developed for use in offices or through an arthroscope, has considerable potential for assessing early osteoarthritic cartilage and monitoring therapeutic effects for cartilage repair with resolution in real time on a scale of micrometers.

Survey of arthroscopy performed by rheumatologists

OBJECTIVE

To determine the international distribution and practice of arthroscopy performed by rheumatologists and to evaluate proposed guidelines on minimum standards for training in arthroscopy in the context of current clinical practice.

METHODS

A questionnaire was sent to all rheumatology centres identified as practising arthroscopy, by (i) searching Medline from 1966 to 1999, (ii) searching the abstract books of the annual general meetings of ACR, BSR and EULAR from 1980 to 1999, and (iii) correspondence with all the centres identified.

RESULTS

Thirty-six rheumatology centres were confirmed as performing arthroscopy (24 in Europe, 10 in USA and two in Australia) and 33 (92%) centres completed the questionnaire. Twenty-five (76%) of the 33 centres performing arthroscopy had started to perform it since 1990 and 72 rheumatologists are now trained in arthroscopy. A total of 16532 arthroscopies had been performed (median=220 arthroscopies/centre, range 20-5000); 50.5% of the arthroscopies had a primary clinical indication and 49.5% had a primary research indication. Most centres fulfilled the minimum standards for arthroscopic facilities and the proposed minimum standards in training were acceptable to 76% of respondents. Complication rates were calculated for 15682 arthroscopies where routine follow-up data were available [joint infection, 16 (0.1%); wound infection, 17 (0.1%); haemarthrosis, 141 (0.9%); deep venous thrombosis, 31 (0.2%); neurological damage, 3 (0.02%), thrombophlebitis, 12 (0.08%), other, 8 (0.06%)]. Irrigation volume correlated with wound infection rate (r=0.41, P=0.03) and centres performing cartilage biopsy had a higher rate of haemarthrosis (P=0.007).

CONCLUSION

The last decade has seen rapid growth in arthroscopy performed by rheumatologists in an out-patient setting under local and regional anaesthesia. Proposed minimum standards for training in rheumatological arthroscopy reflect current practice accurately and are acceptable to the majority of arthroscopists. Complication rates of rheumatological arthroscopy are similar to those reported in the orthopaedic literature.

Intra-articular primatised anti-CD4: efficacy in resistant rheumatoid knees. A study of combined arthroscopy, magnetic resonance imaging, and histology

OBJECTIVES

CD4+ T cells sustain the chronic synovial inflammatory response in rheumatoid arthritis (RA). SB-210396/CE 9.1 is an anti-CD4 monoclonal antibody that has documented efficacy in RA when given intravenously. This study aimed to establish the safety and efficacy of the intra-articular administration of SB-210396/CE 9.1 compared with placebo, examining its mode of action using a combined imaging approach of arthroscopy, magnetic resonance imaging (MRI), and histology.

METHODS

Thirteen RA patients with active, resistant knee synovitis, were randomised to intra-articular injection of placebo (n=3), 0.4 mg (n=3) or 40 mg (n=7) of anti-CD4 after sequential dynamic gadolinium enhanced MRI, followed by same day arthroscopy and synovial membrane biopsy. Imaging and arthroscopic synovial membrane sampling were repeated at six weeks. This study used a unique region of interest (ROI) analysis mapping the MRI area analysed to the specific biopsy site identified arthroscopically, thus providing data for all three modalities at the same synovial membrane site.

RESULTS

12 patients completed the study (one placebo treated patient refused further MRI). Arthroscopic improvement was observed in 0 of 2 placebo patients but in 10 of 10 patients receiving active drug (>20% in 6 of 10). Improvement in MRI was consistently observed in all patients of the 40 mg group but not in the other two groups. A reduction in SM CD4+ score was noted in the 40 mg group and in the 0.4 mg group. Strong correlations both before and after treatment, were identified between the three imaging modalities. Intra-articular delivery of SB-210396/CE 9.1 was well tolerated.

CONCLUSIONS

SB-210396/CE 9.1 is safe when administered by intra-articular injection. A trend toward efficacy was found by coordinated MRI, arthroscopic, and histological imaging, not seen in the placebo group. The value of ROI analysis was demonstrated.