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Cytological assessment of knee effusions
Arthroscopy: The Journal of Arthroscopic and Related Surgery 4(3):174-178
Published by Raven Press, Ltd. © 1988 Arthroscopy Association of North America
Cytological Assessment of Knee Effusions John Older, F.R.C.S., Paul Rollinson, F.R.C.S., and Catherine Pike, M.B. Ch.B.
Summary: Effusion fluid from 80 knee joints was obtained from patients prior to arthroscopy and arthroscopic surgery and submitted to independent physicochemical analysis and cytological examination. The majority of the effusions were secondary to osteoarthrosis and traumatic mechanical derangement. These two conditions gave nonspecific findings on physicochemical analysis and cytology, and the cytologist diagnosed on 13% of these correctly. Cytological examination of fluid from rheumatoid knees revealed ragocytes in just over half the cases, and on this basis, the cytologist was able to correctly diagnose rheumatoid arthritis. Contrary to other reports, we conclude that physicochemical analysis and cytological examination of joint fluid is of little value in the assessment of knees presenting to the orthopaedic surgeon. Key Words: Cytology--Effusion--Knee.
examination with a clinical effusion. The youngest patient was 13, the oldest 86, with a mean of 44 years. Male patients predominated by 1.75 to 1 (Fig. 1) and there was equal distribution between the right and left knee. The aspirated fluid was submitted to physicochemical analysis (of colour, viscosity, and mucin clot), cytological examination, and polarised light microscopy. The fluid was spun down for 5 min at 1,500 r.p.m, and then, if necessary, at 1,500 r.p.m. for 3 min in a cytospin. The deposits were fixed in alcohol and stained with haematoxylin and eosin. These laboratory investigations were performed by the same technician (J.J.), and reported by one cytologist (C.P.), who did not know of the clinical or arthroscopic diagnosis, but based hers on the laboratory investigations. All the patients were under the care of the same orthopaedic surgeon (J.O.) who performed all the arthroscopies, and prepared a detailed report on the arthroscopic findings and any arthroscopic surgery. A definitive diagnosis was made from a review of the clinical features, radiological examination, arthroscopic findings, blood investigations including ESR and autoimmune profile, and microscopy of arthroscopic synovial biopsy specimen where indicated. All the data were investigated independently (P.R.) and then analysed using a computer.
Exfoliative cytology is of proven value in the definitive diagnosis of some diseases, especially certain types of cancer. Polarised-light microscopy for crystals and Gram-staining for bacteria are accepted as very useful tests on joint fluid when the clinical picture suggests a crystal arthropathy or a septic joint. Some reports stress the value of exfoliate cytology and synovial fluid analysis in the diagnosis of the arthritides (1-3). It is claimed that each arthritic disorder has a typical picture on cytological examination and physical analysis of the joint effusion, and that therefore these laboratory investigations are of high diagnostic value. This study was undertaken to reassess the usefulness of cytological and physical analysis of the joint fluid from joints that presented for arthroscopic examination with a clinical effusion. MATERIALS AND METHODS Joint fluid was aspirated from 80 consecutive knees in patients who presented from arthroscopic Department of Orthopaedic Surgery, Department of Pathology, Royal Surrey County Hospital, Guildford, Surrey, U.K. Address correspondence and reprint requests to Mr. John Older at Sandacre, Shalford, Guildford, Surrey GU4 8DX, U.K.
174
CYTOLOGICAL A S S E S S M E N T OF KNEE EFFUSIONS 1A,B
175
20,
'15 10,
o
Male
•
Fema{e
Z
o" 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89
Oo o-oooo,,ooooooo..o.oooooo.o.o,,ooo.o. "o . : 8 80.0 o . o'. °o oo ..... o %
I
l
{
10
20
30
L
40
i
i
50
60
~
70
~
o
I
80
L 90
Age at opera,on (years)
Age at opera'don(years)
FIG. 1. A: Schematic drawing showing age distribution. B: Schematic drawing showing age and sex distribution.
RESULTS The definitive diagnosis of each knee joint is shown in Table 1. The largest group of knees, 41.25%, had a traumatic effusion subdivided into: meniscal lesions, articular cartilage damage, ligament injury, or a combination (Table 2). Most had nonspecific findings on fluid analysis and cytology. Only five patients were diagnosed by the cytologist as having a traumatic effusion; four diagnoses were correct (Table 3). This diagnosis was made when effusion fluid exhibited a strongly positive mucin clot combined with synovial (Fig. 2) and cartilage cells in the presence of numerous polymorphonucleocytes. The second largest group of 30 knees (37.50%) had osteoarthritis. In 26 of these 30 knees the cytological examination and fluid analysis gave only nonspecific findings. The cytologist diagnosed osteoarthritis in only eight knees out of the series of 80, and in four cases this was correct. This diagnosis was based on the findings of numerous synovial cells in sheets with cartilage cells present, but with few inflammatory cells. Cartilage cells are difficult to distinguish and this may explain the lack of cytological success. There were only 11 knees in this series with definite rheumatoid arthritis, and one of these had resolving sepsis. A cytological diagnosis of rheumatoid arthritis based on finding ragocytes (R.A. cells,
Fig. 3) was made only six times by the cytologist, and on each occasion, this was correct. Ragocytes are lobulated neutrophils with granular basophilic inclusions, which are thought by some to be precipitates of the rheumatoid factor, but by others to be degenerate white cells, that have been phagocytosed (4). The cytological diagnosis in four of the remaining five rheumatoid knees was nonspecific, and there was one diagnosis of posttraumatic effusion. Four knees were thought to show urate crystals on polarised light microscopy, and despite the lack of other features, the cytologist diagnosed gout in these four cases. All the patients had normal serum urate levels and, clinically, none of them had the features of an effusion secondary to gout. Intraarticular steroid injections had been given to all these patients up to 6 months before arthroscopy, and polarised light microscopy of the effusion fluid was performed. We believe that the steroid crystals were mistaken for urates. In one knee joint, thought arthroscopically to show rheumatoid arthritis, microscopy of arthroscopic synovial biopsy material showed a picture of tuberculous synovitis. The synovial fluid analysis and cytology were nonspecific in this patient. DISCUSSION The data we present are at variance with the results of other workers. Broderick (1), using criteria
T A B L E 1. Analysis of definitive diagnosis in 80
T A B L E 2. Analysis of traumatic synovitis in 33
knee joints
knee joints
Diagnosis Traumatic synovitis Osteoarthritis Rheumatoid arthritis Nonspecific synovial hypertrophy Tuberculous synovitis
Number of knees
Percent
Diagnosis
Number of knees
33 30 11
41.25 37.50 13.75
5 1
6.25 1.25
Meniscal lesions Articular cartilage lesions Ligament lesions Combination of above items Fat impingement syndrome Synovial hypertrophy
14 8 6 3 1 1
Arthroscopy, Vol. 4, No. 3, 1988
176
J. O L D E R E T A L .
T A B L E 3. Analysis o f cytological diagnosis in each
major diagnostic group
Diagnosis Traumatic synovitis Nonspecific a Osteoarthritis Traumatic effusion Gout Osteoarthritis Nonspecific ~ Osteoarthritis Rheumatoid arthritis Rheumatoid arthritis Rheumatoid arthritis and sepsis Nonspecific a a
Number o f knees 33 21 4 4 4 30 26 4 11 5
Positive True
False
u," lJ
t,,,' JJ
1 5
Nonspecific, noncontributory.
established by Naib (2), gave a correct diagnosis after exfoliative cytology and fluid analysis in over 90% of 126 joint fluid specimens. Similarly, Bhatia (3) concluded that cytology had wide diagnostic and therapeutic applications, and the findings for each group of arthritides were constant and reproducible. Our study analysed a consecutive series of 80 knees in patients with knee disorders presenting for arthroscopic examination and surgery who had an effusion of their knee joints. In such a group, many might well have a posttraumatic effusion that had been present for several weeks or months. In twothirds of these patients with a proven posttraumatic effusion, the cytological diagnosis was nonspecific. Inflammatory cells, mainly polymorphonucleocytes, synovial cells in sheet, and degenerating cartilage cells said to be numerous in traumatic effusions were only seen in 12% of our patients. Cartilage cells, particularly degenerating ones, are difficult to identify cytologically, and this may explain our failure to diagnose traumatic effusions more frequently by cytological investigation. The cytological assessment of knees with proven rheumatoid arthritis was, however, more informative. Just over half these knees were correctly diagnosed by cytology. Effusion fluid from rheumatoid joints is said to be characterised by a decreased viscosity, poor mucin clot, a high white cell count (usually over 70% of polymorphs), degenerate synovium, and no cartilage cells (1-3). These features were seen in the rheumatoid knees in our study, but rarely present altogether. The single most important feature of rheumatoid Arthroscopy, Vol. 4, No. 3, 1988
arthritis is the presence of lobulated neutrophils containing granular intracytoplasmic inclusions. These have been called rheumatoid arthritis cells (5) or ragocytes (6), and can be seen in a high proportion of cases of rheumatoid arthritis, but similar inclusions are sometimes found in other types of inflammatory effusion (7). Ragocytes were seen in six effusions correctly diagnosed as rheumatoid arthritis by the cytologist. There were no false positive cytological diagnoses of rheumatoid arthritis. Papillary aggregates of synovial cells (Fig. 4) are said to be characteristic of pigmented villonodular synovitis. We had 13 effusions with papillary aggregates. The diagnosis was osteoarthritis in nine knees and traumatic effusion in four knees. There were no cases of pigmented villonodular synovitis. Those knees diagnosed by the cytologist as having gouty arthritis presented an interesting problem. The reports of gouty crystals seen by polarised light microscopy caused initial confusion in the management of some patients. Corticosteroid crystals can be confused with other crystal deposits (8), and we think this happened in our four cases where steroids were known to have been injected into the joints up to 6 months before. Steroid crystals are similar in shape to the needle-like urate crystals, but are approximately twice the size, and if facilities to accurately measure the crystals are not available they are easily confused. We suggest the clinician questions the sighting of urate crystals if other clinical features do not suggest gout. Laboratory investigations of synovial fluid by physico-chemical examination and cytology were found to be variable in this study for almost all the arthritic knee disorders in our patients. Cytological assessment gave nonspecific findings in over 70% of the knee effusions examined. When a cytological diagnosis of osteoarthritis, traumatic effusion, or rheumatoid arthritis was made by the cytologist, it was only correct in 72% of knees. We accept the discrepancy between our findings and the work of others who have shown a correlation between the cytological and clinical diagnosis. These papers however, give no clear definition of the criteria used for the clinical diagnosis, and do not show how independent were the cytological and clinical assessments. Arthroscopy and arthroscopic biopsy allow direct visualisation of the structures within the knee joint, and this also enables a more accurate definitive diagnosis to be made. Our work involved only effusion fluid from the knee joint. Others, notably Broderick (1), used the
FIG. 2. Photomicrograph of synovial cells. (Haematoxylin and eosin stained). Line of three large cells on left with large central cluster. FIG. 3. Photomicrograph showing good examples of ragocytes (arrows) (Haematoxylin and eosin stained).
Arthroscopy, Vol. 4, No. 3, 1988
178
J. O L D E R
ET AL.
FIG. 4. Photomicrograph showing long papillary aggregates of synovial cells. (Haematoxylin and eosin stained).
knee joint as the most c o m m o n source of effusion fluid, but some of the submitted fluids were taken from the shoulder, elbow, and other joints, which may have further significance. This was a blind trial in which the cytologist did not know of the clinical or postarthroscopic diagnoses, so that the definitive and cytological diagnosis was determined only when all the results were studied in retrospect. We conclude from our data that whilst cytological examination of effusion fluid m a y be a useful adjunct in the diagnosis o f rheumatoid arthritis, it is o f little or no value in the definitive diagnosis of other disorders of the knee joint (9) presenting to the orthopaedic surgeon. Acknowledgments: We thank Jean Jones, chief technician, for her work in the cytology laboratory, and Bobbin Baxter for data analysis using a computer and her editorial assistance in the preparation of this manuscript.
Arthroscopy, Vol. 4, No. 3, 1988
REFERENCES 1. Broderick PA, Corvese N, Pierik MG, Pike RF, Mariorenzi AL. Exfoliative cytology interpretation of synovial fluid in joint diseases. J Bone Joint Surg 1976;58A:396-9. 2. Naib ZM. Cytology of synovial fluids. Acta Cytol (Baltimore) 1973;17:299-309. 3. Bhatia A, Kapoor S, Vishawakarma GK, Sagreiya K, Ashokraj G. Cytology as a diagnostic aid in arthritis. Indian J Med Res 1981;73:761-7. 4. Bjelle A, Norberg B, Sjogren G. The cytology of joint exudates in rheumatoid arthritis. Scand J Rheumatol 1982; 11:124-8. 5. Hollander JL, Jessar RA, McCarty DJ. Synovianalysis: an aid in arthritic diagnosis. Bull Rheum Dis 1961;12:263--4. 6. Henderson DRF, Jayson MIV, Tribe CR. Lack of correlation of synovial histology with joint damage in rheumatoid arthritis. Ann Rheum Dis 1975;34:7-11. 7. Scott JT. The analysis of joint fluids. Brit J Hosp Med 1975;14:653-8. 8. Blau SP. The synovial fluid. Orthop Clin North A m 1979;10:21-35. 9. McKenna CH. Laboratory diagnosis of rheumatoid arthritis and related disorders. Orthop Clin North A m 1979;10:315-8.
Published by Raven Press, Ltd. © 1988 Arthroscopy Association of North America
Cytological Assessment of Knee Effusions John Older, F.R.C.S., Paul Rollinson, F.R.C.S., and Catherine Pike, M.B. Ch.B.
Summary: Effusion fluid from 80 knee joints was obtained from patients prior to arthroscopy and arthroscopic surgery and submitted to independent physicochemical analysis and cytological examination. The majority of the effusions were secondary to osteoarthrosis and traumatic mechanical derangement. These two conditions gave nonspecific findings on physicochemical analysis and cytology, and the cytologist diagnosed on 13% of these correctly. Cytological examination of fluid from rheumatoid knees revealed ragocytes in just over half the cases, and on this basis, the cytologist was able to correctly diagnose rheumatoid arthritis. Contrary to other reports, we conclude that physicochemical analysis and cytological examination of joint fluid is of little value in the assessment of knees presenting to the orthopaedic surgeon. Key Words: Cytology--Effusion--Knee.
examination with a clinical effusion. The youngest patient was 13, the oldest 86, with a mean of 44 years. Male patients predominated by 1.75 to 1 (Fig. 1) and there was equal distribution between the right and left knee. The aspirated fluid was submitted to physicochemical analysis (of colour, viscosity, and mucin clot), cytological examination, and polarised light microscopy. The fluid was spun down for 5 min at 1,500 r.p.m, and then, if necessary, at 1,500 r.p.m. for 3 min in a cytospin. The deposits were fixed in alcohol and stained with haematoxylin and eosin. These laboratory investigations were performed by the same technician (J.J.), and reported by one cytologist (C.P.), who did not know of the clinical or arthroscopic diagnosis, but based hers on the laboratory investigations. All the patients were under the care of the same orthopaedic surgeon (J.O.) who performed all the arthroscopies, and prepared a detailed report on the arthroscopic findings and any arthroscopic surgery. A definitive diagnosis was made from a review of the clinical features, radiological examination, arthroscopic findings, blood investigations including ESR and autoimmune profile, and microscopy of arthroscopic synovial biopsy specimen where indicated. All the data were investigated independently (P.R.) and then analysed using a computer.
Exfoliative cytology is of proven value in the definitive diagnosis of some diseases, especially certain types of cancer. Polarised-light microscopy for crystals and Gram-staining for bacteria are accepted as very useful tests on joint fluid when the clinical picture suggests a crystal arthropathy or a septic joint. Some reports stress the value of exfoliate cytology and synovial fluid analysis in the diagnosis of the arthritides (1-3). It is claimed that each arthritic disorder has a typical picture on cytological examination and physical analysis of the joint effusion, and that therefore these laboratory investigations are of high diagnostic value. This study was undertaken to reassess the usefulness of cytological and physical analysis of the joint fluid from joints that presented for arthroscopic examination with a clinical effusion. MATERIALS AND METHODS Joint fluid was aspirated from 80 consecutive knees in patients who presented from arthroscopic Department of Orthopaedic Surgery, Department of Pathology, Royal Surrey County Hospital, Guildford, Surrey, U.K. Address correspondence and reprint requests to Mr. John Older at Sandacre, Shalford, Guildford, Surrey GU4 8DX, U.K.
174
CYTOLOGICAL A S S E S S M E N T OF KNEE EFFUSIONS 1A,B
175
20,
'15 10,
o
Male
•
Fema{e
Z
o" 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89
Oo o-oooo,,ooooooo..o.oooooo.o.o,,ooo.o. "o . : 8 80.0 o . o'. °o oo ..... o %
I
l
{
10
20
30
L
40
i
i
50
60
~
70
~
o
I
80
L 90
Age at opera,on (years)
Age at opera'don(years)
FIG. 1. A: Schematic drawing showing age distribution. B: Schematic drawing showing age and sex distribution.
RESULTS The definitive diagnosis of each knee joint is shown in Table 1. The largest group of knees, 41.25%, had a traumatic effusion subdivided into: meniscal lesions, articular cartilage damage, ligament injury, or a combination (Table 2). Most had nonspecific findings on fluid analysis and cytology. Only five patients were diagnosed by the cytologist as having a traumatic effusion; four diagnoses were correct (Table 3). This diagnosis was made when effusion fluid exhibited a strongly positive mucin clot combined with synovial (Fig. 2) and cartilage cells in the presence of numerous polymorphonucleocytes. The second largest group of 30 knees (37.50%) had osteoarthritis. In 26 of these 30 knees the cytological examination and fluid analysis gave only nonspecific findings. The cytologist diagnosed osteoarthritis in only eight knees out of the series of 80, and in four cases this was correct. This diagnosis was based on the findings of numerous synovial cells in sheets with cartilage cells present, but with few inflammatory cells. Cartilage cells are difficult to distinguish and this may explain the lack of cytological success. There were only 11 knees in this series with definite rheumatoid arthritis, and one of these had resolving sepsis. A cytological diagnosis of rheumatoid arthritis based on finding ragocytes (R.A. cells,
Fig. 3) was made only six times by the cytologist, and on each occasion, this was correct. Ragocytes are lobulated neutrophils with granular basophilic inclusions, which are thought by some to be precipitates of the rheumatoid factor, but by others to be degenerate white cells, that have been phagocytosed (4). The cytological diagnosis in four of the remaining five rheumatoid knees was nonspecific, and there was one diagnosis of posttraumatic effusion. Four knees were thought to show urate crystals on polarised light microscopy, and despite the lack of other features, the cytologist diagnosed gout in these four cases. All the patients had normal serum urate levels and, clinically, none of them had the features of an effusion secondary to gout. Intraarticular steroid injections had been given to all these patients up to 6 months before arthroscopy, and polarised light microscopy of the effusion fluid was performed. We believe that the steroid crystals were mistaken for urates. In one knee joint, thought arthroscopically to show rheumatoid arthritis, microscopy of arthroscopic synovial biopsy material showed a picture of tuberculous synovitis. The synovial fluid analysis and cytology were nonspecific in this patient. DISCUSSION The data we present are at variance with the results of other workers. Broderick (1), using criteria
T A B L E 1. Analysis of definitive diagnosis in 80
T A B L E 2. Analysis of traumatic synovitis in 33
knee joints
knee joints
Diagnosis Traumatic synovitis Osteoarthritis Rheumatoid arthritis Nonspecific synovial hypertrophy Tuberculous synovitis
Number of knees
Percent
Diagnosis
Number of knees
33 30 11
41.25 37.50 13.75
5 1
6.25 1.25
Meniscal lesions Articular cartilage lesions Ligament lesions Combination of above items Fat impingement syndrome Synovial hypertrophy
14 8 6 3 1 1
Arthroscopy, Vol. 4, No. 3, 1988
176
J. O L D E R E T A L .
T A B L E 3. Analysis o f cytological diagnosis in each
major diagnostic group
Diagnosis Traumatic synovitis Nonspecific a Osteoarthritis Traumatic effusion Gout Osteoarthritis Nonspecific ~ Osteoarthritis Rheumatoid arthritis Rheumatoid arthritis Rheumatoid arthritis and sepsis Nonspecific a a
Number o f knees 33 21 4 4 4 30 26 4 11 5
Positive True
False
u," lJ
t,,,' JJ
1 5
Nonspecific, noncontributory.
established by Naib (2), gave a correct diagnosis after exfoliative cytology and fluid analysis in over 90% of 126 joint fluid specimens. Similarly, Bhatia (3) concluded that cytology had wide diagnostic and therapeutic applications, and the findings for each group of arthritides were constant and reproducible. Our study analysed a consecutive series of 80 knees in patients with knee disorders presenting for arthroscopic examination and surgery who had an effusion of their knee joints. In such a group, many might well have a posttraumatic effusion that had been present for several weeks or months. In twothirds of these patients with a proven posttraumatic effusion, the cytological diagnosis was nonspecific. Inflammatory cells, mainly polymorphonucleocytes, synovial cells in sheet, and degenerating cartilage cells said to be numerous in traumatic effusions were only seen in 12% of our patients. Cartilage cells, particularly degenerating ones, are difficult to identify cytologically, and this may explain our failure to diagnose traumatic effusions more frequently by cytological investigation. The cytological assessment of knees with proven rheumatoid arthritis was, however, more informative. Just over half these knees were correctly diagnosed by cytology. Effusion fluid from rheumatoid joints is said to be characterised by a decreased viscosity, poor mucin clot, a high white cell count (usually over 70% of polymorphs), degenerate synovium, and no cartilage cells (1-3). These features were seen in the rheumatoid knees in our study, but rarely present altogether. The single most important feature of rheumatoid Arthroscopy, Vol. 4, No. 3, 1988
arthritis is the presence of lobulated neutrophils containing granular intracytoplasmic inclusions. These have been called rheumatoid arthritis cells (5) or ragocytes (6), and can be seen in a high proportion of cases of rheumatoid arthritis, but similar inclusions are sometimes found in other types of inflammatory effusion (7). Ragocytes were seen in six effusions correctly diagnosed as rheumatoid arthritis by the cytologist. There were no false positive cytological diagnoses of rheumatoid arthritis. Papillary aggregates of synovial cells (Fig. 4) are said to be characteristic of pigmented villonodular synovitis. We had 13 effusions with papillary aggregates. The diagnosis was osteoarthritis in nine knees and traumatic effusion in four knees. There were no cases of pigmented villonodular synovitis. Those knees diagnosed by the cytologist as having gouty arthritis presented an interesting problem. The reports of gouty crystals seen by polarised light microscopy caused initial confusion in the management of some patients. Corticosteroid crystals can be confused with other crystal deposits (8), and we think this happened in our four cases where steroids were known to have been injected into the joints up to 6 months before. Steroid crystals are similar in shape to the needle-like urate crystals, but are approximately twice the size, and if facilities to accurately measure the crystals are not available they are easily confused. We suggest the clinician questions the sighting of urate crystals if other clinical features do not suggest gout. Laboratory investigations of synovial fluid by physico-chemical examination and cytology were found to be variable in this study for almost all the arthritic knee disorders in our patients. Cytological assessment gave nonspecific findings in over 70% of the knee effusions examined. When a cytological diagnosis of osteoarthritis, traumatic effusion, or rheumatoid arthritis was made by the cytologist, it was only correct in 72% of knees. We accept the discrepancy between our findings and the work of others who have shown a correlation between the cytological and clinical diagnosis. These papers however, give no clear definition of the criteria used for the clinical diagnosis, and do not show how independent were the cytological and clinical assessments. Arthroscopy and arthroscopic biopsy allow direct visualisation of the structures within the knee joint, and this also enables a more accurate definitive diagnosis to be made. Our work involved only effusion fluid from the knee joint. Others, notably Broderick (1), used the
FIG. 2. Photomicrograph of synovial cells. (Haematoxylin and eosin stained). Line of three large cells on left with large central cluster. FIG. 3. Photomicrograph showing good examples of ragocytes (arrows) (Haematoxylin and eosin stained).
Arthroscopy, Vol. 4, No. 3, 1988
178
J. O L D E R
ET AL.
FIG. 4. Photomicrograph showing long papillary aggregates of synovial cells. (Haematoxylin and eosin stained).
knee joint as the most c o m m o n source of effusion fluid, but some of the submitted fluids were taken from the shoulder, elbow, and other joints, which may have further significance. This was a blind trial in which the cytologist did not know of the clinical or postarthroscopic diagnoses, so that the definitive and cytological diagnosis was determined only when all the results were studied in retrospect. We conclude from our data that whilst cytological examination of effusion fluid m a y be a useful adjunct in the diagnosis o f rheumatoid arthritis, it is o f little or no value in the definitive diagnosis of other disorders of the knee joint (9) presenting to the orthopaedic surgeon. Acknowledgments: We thank Jean Jones, chief technician, for her work in the cytology laboratory, and Bobbin Baxter for data analysis using a computer and her editorial assistance in the preparation of this manuscript.
Arthroscopy, Vol. 4, No. 3, 1988
REFERENCES 1. Broderick PA, Corvese N, Pierik MG, Pike RF, Mariorenzi AL. Exfoliative cytology interpretation of synovial fluid in joint diseases. J Bone Joint Surg 1976;58A:396-9. 2. Naib ZM. Cytology of synovial fluids. Acta Cytol (Baltimore) 1973;17:299-309. 3. Bhatia A, Kapoor S, Vishawakarma GK, Sagreiya K, Ashokraj G. Cytology as a diagnostic aid in arthritis. Indian J Med Res 1981;73:761-7. 4. Bjelle A, Norberg B, Sjogren G. The cytology of joint exudates in rheumatoid arthritis. Scand J Rheumatol 1982; 11:124-8. 5. Hollander JL, Jessar RA, McCarty DJ. Synovianalysis: an aid in arthritic diagnosis. Bull Rheum Dis 1961;12:263--4. 6. Henderson DRF, Jayson MIV, Tribe CR. Lack of correlation of synovial histology with joint damage in rheumatoid arthritis. Ann Rheum Dis 1975;34:7-11. 7. Scott JT. The analysis of joint fluids. Brit J Hosp Med 1975;14:653-8. 8. Blau SP. The synovial fluid. Orthop Clin North A m 1979;10:21-35. 9. McKenna CH. Laboratory diagnosis of rheumatoid arthritis and related disorders. Orthop Clin North A m 1979;10:315-8.