Wear, 90 (1983) 107 - 111 107

A PRELIMINARY USE OF FERROGR~HY IN THE STUDY OF ARTHRITIC DISEASES*

G. H. MILLS?

Metallurgy department, Brunet University, Uxbridge UB8 3PH (Gt. Britain)

J. A. HUNTER

Centre for Rheumatic Diseases, Gartnavel General Hospital, 1053 Great Western Road, Glasgow G1.2 OYN (Gt. Britain)

(Received November 17, 1982)

Summary

Ferrography applied as a failure analysis or condition monitoring tech- nique to engineering components has proved successful over the past decade.

As human joints are similar to some lubricated en~neering components it is natural to consider the application of ferrography to the examination of “wear particles” in synovial fluid obtained from human joints. An at- tempt to compare the number and type of wear particles with the extent of damage to articular surfaces has been undertaken with some limited success.

1. Introduction

It has been known for over 30 years that human synovial fluid con- tained particulate matter. Hollander [l] suggested the possibility that the number of particles present correlated with the condition of the corre- sponding articular surfaces. No technique was capable of producing a clear and concise separation of the particles to allow an efficient examination by microscopical methods. Ferrography 12, 31 was devised to investigate the occurrence of metallic wear particles in lubricated moving components. The success of this magnetic separation technique in engineering systems, al- lowing component history to be interpreted, has led to many refinements of its use in wider applications. As human joints are bearings lubricated with synovial fluid, ferrography may be applicable. The main difficulty is the non-magnetic characteristic of the articular components. This has been

*Paper presented at the First International Conference on Advances in Ferrography, University College, Swansea, Gt. Britain, September 22 - 24, 1982.

‘Present address: Monitoring Analysis Service, 21 Hairmyres Park, East Kilbride, Glasgow G75 8SS, Gt. Britain.

0043-1648183/$3.00 @ Elsevier Sequoia/~inted in The Netherlands

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overcome by the use of a magnetizing solution enabling the wear particles to be precipitated onto the normal ferrographic substrate. The method of preparation is recorded elsewhere [4, 51.

The purpose of this study is to explore the potential of fenography in rheumatological practice and research and in particular to establish whether particles recovered from synovial fluid are related to joint wear.

2. Results

Synovial fluid is the substance which separates the two opposing sur- faces of most human joints. If diseased joints produce particles, then these should be contained in the synovial fluid.

In this study approximately 50 patients with knee effusions had aspi- rations performed with full recommended aseptic precautions. All required therapeutic or diagnostic procedure on clinical grounds. Samples were taken from patients in a number of diagnostic categories. These, however, will not be discussed here.

Fenograms were prepared using 2.5 ml of the synovial fluid. They were examined using transmitted and reflected light in both the polarized and the unpolarized modes and scanning electron microscopy techniques. Particles were identified by X-ray energy analysis. Control samples were obtained from saline washings of aspiration needles, syringes and the heparinized spec- imen tubes. No similar particulate material was found.

Ex~ination of the Ferrograms revealed a wide range of particle size from submicrometre up to approximately 2 mm. Several different types of cartilaginous particles were observed. All the cartilage particles exhibited brightness to some degree when viewed in polarized light. Large particles of cartilage (Fig. 1) were generally “chunky” in appearance with surface markings typical of cleavage fracture.

The second type of cartilage particle was thin flakes which often had a light grey appearance (Fig. 2(a)). Figure 2(b) is a scanning electron micro- graph of this type of cartilage particle. Another type of cartilage particle was almost transparent in the optical microscope (Fig. 3(a)). A scanning electron

Fig. 1. Chunky-type cartilage particles in reflected polarized light.

(4 (b)

Fig. 2. Thin plates of cartilage in (a) reflected polarized light and (b) a scanning electron micrograph.

(a) (b)

Fig. 3. Transparent plates of cartilage in (a) reflected polarized light and (b) a scanning electron micrograph.

microscopy micrograph of a similar type of particle is shown in Fig. 3(b). Cleavage-type surface marks are clearly evident at one end of this particle. Spherical particles were observed in some specimens as shown in Fig. 2(b); these ranged in size from 2 to 20 pm. A few fibrous particles were noted in all the different categories of samples examined.

Some samples contained a particular type of mixed fibrous material, composed of tangles of fibres throughout a semiopaque-matrix-like material (Fig. 4(a)). At higher magnification, using polarized light, this particulate material appeared to comprise very small particles. It was difficult to re- solve owing to the brightness from what seemed to be individual facets and

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(a) (b)

Fig, 4. Mixed fibres and opaque matrix material in (a) reflected polarized light and (b) a scanning electron micrograph.

(a) (b)

Fig. 5. Particles of bone in (a) reflected polarized light and (b) a scanning electron micro- graph.

Fig. 4(b) is a scanning electron micrograph of similar material. Small “crystal- like” particles were also observed. They were usually in agglomerates and were difficult to size accurately.

In all the samples examined the bone particles were all of a similar na- ture. They have an intense white snow flake appearance under polarized light (Fig. 5(a)). A few large particles were occasionally noted (Fig. 5(b)).

Some Ferrograms had a background of opaque material. This was thought to be proteinaceous material which had not been fully removed during the preparation of the Ferrogram. It was never present in sufficient quantity to obscure any appreciable number of the particles of interest.

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Identification of the cartilaginous and bone particles was effected with tissue stains, Alcian Blue for the mucopolysaccharide of the former and Alizarin Red S for the calcium of the latter. These stains were corroborated by the use of X-ray energy analysis to identify the presence of sulphur and calcium in the relevant particles. It was noted that the sample from some patients had significantly more large particles (greater than 100 pm in size) present.

A standard sample from what was considered to be a normal knee contained two large cartilage particles, significantly fewer of the smaller cartilage particles and no evidence of the presence of any bone particles.

3. Discussion

The separation of particulate material from human synovial fluid by ferrographic techniques has proved to be successful. The majority of par- ticles present in the synovial fluid appear to be recovered. Identification of the particles is possible by using biological stains or X-ray analysis. In most cases it was difficult to attribute a particular type of particle to a specific category of arthritic disease. In all cases samples from patients with seropositive rheumatoid arthritis on systemic corticosteroid drugs had a greater number of large particles (greater than 100 pm in size) present. The large particles appeared to be cartilage material.

References

1 J. L. Hollander, A. Reginato and T. P. Torralba, Examination of synovial fluid as a diagnostic aid in arthritis, Med. Clin. North Am., 50 (1966) 1281 - 1293.

2 W. W. Siefert and V. C. Westcott, A method for the study of wear particles in lubri- cating oil, Wear, 21 (1972) 27 - 42.

3 D. Scott and G. H. Mills, Spherical debris - its occurrence, formation and significance in rolling contact fatigue, Wear, 24 (1973) 235 - 242.

4 D. C. Mears, E. N. Hanley, Jr., R. Rutowski and V. C. Westcott, Ferrography: its application to the study of human joint wear, Wear, 50 (1978) 115 - 125.

5 C. H. Evans, E. R. Bowen, J. Bowen, W. P. Tew and V. C. Westcott, Synovial fluid analysis by ferrography, J. Biochem. Biophys. Meth., 2 (1980) 11 - 18.