Radiological measurement of OA evolution of the cartilage joint thickness (normal and abnormal thickness)

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Abstracts

P a t t e r n s and a s s o c i a t i o n s o f k n e e o s t e o a r t h r i t i s JOANNA LEDINGHAM, MARI~N REGAN AND MICHAEL DOHERTY

Rheumatology Unit, Nottingham, U.K. Despite being a common condition, little is k n o w n a b o u t p a t t e r n s and a s s o c i a t i o n s of knee o s t e o a r t h r i t i s (OA). This large cross-sectional s t u d y was u n d e r t a k e n to address these further. Two h u n d r e d and fifty-two p a t i e n t s (F 161:M 91; m e a n age 70 years, r a n g e 34-91 years) referred with k n e e OA were studied. E a c h u n d e r w e n t full c l i n i c a l a n d r a d i o g r a p h i c r h e u m a t o l o g i c a l screening. F o u r t e e n per c e n t h a d u n i l a t e r a l and 86% b i l a t e r a l r a d i o g r a p h i c knee OA (definite n a r r o w i n g + / - o t h e r OA features). Of these 470 knees with OA, 6% h a d t r i c o m p a r t m e n t a l and 59~/o b i c o m p a r t m e n t a l disease. I s o l a t e d patello-femoral (PF) OA o c c u r r e d in 24% and tibio-femoral in 11% [medial c o m p a r t m e n t (MTF) 10%; l a t e r a l (LTF) 1%]. T h e P F and M T F c o m p a r t m e n t s were most commonly (85%), and t h e M T F a n d L T F c o m p a r t m e n t s least commonly (1%) involved in b i c o m p a r t m e n t a l disease.

S e v e n t y - e i g h t p a t i e n t s (30%) had knee c h o n d r o c a l c i n o . sis and 23% of OA knees h a d calcium p y r o p h o s p h a t e d i h y d r a t e (CPPD) c r y s t a l s identified in t h e i r synovial fluid. CPPD c r y s t a l s were a s s o c i a t e d w i t h severe OA ( K e l l g r e n grade 4), m a r k e d osteophytosis, a t t r i t i o n and cyst formation. M u l t i p l e clinical nodes and radiog r a p h i c p o l y - a r t i c u l a r i n t e r p h a l a n g e a l OA (each > 3 rays, both hands) were more common in women and o c c u r r e d in 22% and 26% of patients, respectively. F o r e s t i e r ' s d i s e a s e : w a s p r e s e n t in 4% a n d showed no a s s o c i a t i o n with i n d i v i d u a l r a d i o g r a p h i c f e a t u r e s of OA or with p a t t e r n s of bone response. This s t u d y confirms t h a t knee OA (in a hospital referred population) is most commonly b i l a t e r a l and m u l t i - c o m p a r t m e n t a l a n d t h a t severe r a d i o g r a p h i c c h a n g e s a s s o c i a t e with CPPD c r y s t a l deposition.

Bone s c i n t i g r a p h y predicts the o u t c o m e o f k n e e o s t e o a r t h r i t i s P. DIEPPE, J. CUSHNAGHAN, P. YOUNG, J. KRIWAN, F. MCCRAE AND I. WATT

Rheumatology Unit, Bristol Royal Infirmary, Bristol, U.K. T e c h n e t i u m 99 labeled d i p h o s p h o n a t e s a r e p r e f e r e n t i a l l y r e t a i n e d in or a r o u n d o s t e o a r t h r i t i c k n e e joints. Different p a t t e r n s of r e t e n t i o n have been c o r r e l a t e d w i t h c l i n i c a l and r a d i o g r a p h i c features. It has been s u g g e s t e d t h a t t h e scan m a y reflect aspects of the OA disease process r e l e v a n t to p r o g r e s s i o n a n d outcome. N i n t e t y - f o u r p a t i e n t s (65 female, m e a n age 64.2 years, m e a n disease d u r a t i o n 9.4 years) with k n e e pain and r a d i o g r a p h i c evidence of OA in one or b o t h knees were seen i n i t i a l l y and e x a m i n e d clinically, r a d i o g r a p h i c a l l y a n d by e a r l y and l a t e phase bone scans. The group was r e v i e w e d after a mean i n t e r v a l of 67.3 months, r a n g e 60-72, when c l i n i c a l e x a m i n a t i o n and r a d i o g r a p h s were repeated. All r a d i o g r a p h s and scans were examined s e p a r a t e l y by an i n d e p e n d e n t observer, b l i n d e d to the d a t e order of r a d i o g r a p h s . R a d i o g r a p h s were examined for i n d i v i d u a l features of OA in each c o m p a r t m e n t i n c l u d i n g a m e a s u r e m e n t of i n t e r bone d i s t a n c e (mm) in the tibiofemoral c o m p a r t m e n t s .

M a j o r s c i n t i g r a p h i c a b n o r m a l i t i e s were r e c o r d e d as p r e s e n t (103) or a b s e n t (82). Cross-sectional a n a l y s i s at e n t r y i n d i c a t e d t h a t only; 75% of s c a n a b n o r m a l i t i e s could be a t t r i b u t e d to clinical and X-ray features. D u r i n g t h e 5-year i n t e r v a l 10 p a t i e n t s died, nine were lost to follow-up. S c i n t i g r a p h i c a b n o r m a l i t i e s were p r e s e n t at e n t r y in all of the 22 knees (15 patients), coming to surgery, (P < 0.0001). E n t r y s c a n s also correlated s t r o n g l y with s u b s e q u e n t j o i n t space n a r r o w i n g . Two mm or more loss of j o i n t space o c c u r r e d in 14 knees all of w h i c h had isotope retention. In c o n t r a s t , of 72 knees with no loss of j o i n t space only 25 (34.7%) had scan a b n o r m a l i t i e s ( P = 0.0002). W e a k e r c o r r e l a t i o n s were observed with g r o w t h of o s t e o p h y t e ( P = 0.03). In conclusion, an a b n o r m a l scan p r e d i c t e d s u r g e r y or j o i n t space loss of 142 knees with OA over a 5-year time period. This suggests isotope r e t e n t i o n reflects an aspect of the disease process r e l e v a n t to progression.

A S S E S S M E N T OF OSTEOARTHRITIS AND THERAPY IN HUMANS Radiological m e a s u r e m e n t o f OA e v o l u t i o n o f the cartilage joint t h i c k n e s s ( n o r m a l and a b n o r m a l t h i c k n e s s ) A. CHEVROT

Radiologie B, Hdpital Cochin, Paris, France M e a s u r i n g a r t i c u l a r c a r t i l a g e t h i c k n e s s is especially difficult in o s t e o a r t h r i t i s as c a r t i l a g e loss is often focal. S e v e r a l methods a r e in use. The oldest and p r o b a b l y the safest t e c h n i q u e is from X-rays. The use of a h a r d tip compass i n s t e a d of a

s t a n d a r d r u l e r on plain X-ray films f a c i l i t a t e measurement. But this t e c h n i q u e is only possible on special joints (e.g. hip). F u r t h e r m o r e , it only gives the global t h i c k n e s s of both c a r t i l a g e s of a joint. A r t h r o g r a p h y and more so computed t o m o g r a p h y

Osteoarthritis and Cartilage Vol. 1 No. 1

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i:i[--:',

: ~ h r o g r a p h y directly show joint cartilage thickness. ~hi~::: can be useful for detection of either cartilage :~inning, focal destruction or ulcer. However, this is an :i:hvasive technique, and difficult to use routinely one or t~9~:: times a year while following the treatment of ~os~eoarthritis. :~~ l : t r a s o u n d measurement can be used in special areas ~ilk~ femoral condyles, and its use merits for study. Its ~ e t Y is not yet understood. !iiiii!.~Magnetic resonance imaging (MRI) is a safe, repeat-

able, accurate method for measuring cartilage thickness in all areas. Meanwhile, the MRI of cartilage defects and also the subchondral bone plate thickness are not well established, due to artefacts and size of the pixel of the images. Further evaluation is necessary. MRI could become the best investigative tool in the foreseeable future. Presently, any work studying cartilage thickness measurement and osteoarthritis should use several techniques including plain X-ray or MRI.

Biological m e a s u r e m e n t of o s t e o a r t h r i t i s EUGENE THONAR

Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL, U.S.A. !Th4 diagnosis of osteoarthritis (OA) is made on the basis ~f ~ h clinical symptoms and radiological evidence of i~r~{lage destruction. As an increase in the degradation i~:~eiements of the articular cartilage matrix is initiated ~ n g before articular cartilage shows signs of destruc: ~ n , measurements of degradation products of carti[!~ge-specific molecules in body fluids may help identify iab:fiormal processes occurring early in the disease. :~ensitive immunoassays which quantify cartilages~eclfic epltopes m joint fluid, serum and urine are ~ a b l i n g researchers and clinicians to learn more about ::dhanges which take place in early OA. For example, tJ:~'0spective studies of joint fluid markers in individuals ~i~h knee injury, who are at an increased risk of deve~bping post-traumatic OA, have shown that an acceleratfbn in the metabolism of aggrecan, collagen type II and matrix proteins occurs within days following the injury and is sustained, although at a lower level, for several years. A major goal of these studies is to correlate these early changes in the joint fluid level of specific markers with the development of OA in later years. W h i l e markers in joint fluid provide information about changes taking place in a single joint, cartilagespecific markers in serum or urine offer a measure of systemic changes which affect the many cartilaginous structures in the body. Thus, measurements of the serum level of a keratan sulfate (KS) epitope present on carti-

lage-derived aggrecan fragments already have proved useful in monitoring the response of cartilages in vivo. It is now known that the oral administration of most nonsteroidal drugs has little effect on the metabolism of cartilage aggrecan while prednisone, given orally or intra-articularly, causes a marked suppression of aggrecan catabolism. Measurements of the serum level of the KS epitope also have been used to examine the effects of exercise and immobilization on the metabolism of cartilage aggrecan. In OA, the serum level of the KS epitope often is elevated, especially in patients with multiple joint involvement. The serum level of KS shows some correlation with the number of joints involved but not with the severity of the cartilage lesions. A single measurement of the serum level of the KS epitope thus is not a useful marker of the severity of the cartilage lesions. Prospective studies are in progress to test the hypothesis that this elevation occurs during the early stages of OA prior to the development of cartilage lesions. We also have observed that transection of the anterior cruciate ligament in the dog gives rise, after a delay of 1-2 weeks, to a change in the serum level of KS, which we believe is indicative of a systemic hypermetabolic response of chondrocytes to factors released from the destabilized joint. The significance of these findings will be discussed.

Cartilage m a r k e r s in s y n o v i a l fluid and early diagnosis of k n e e j o i n t osteoarthritis INGEMAR PETERSSON, TORE SAXNE, BJ(3RN SVENSSON AND DICK NEINEG~RD

Spenshult's Hospital for Rheumatic Diseases, Halmstad, Department of Rheumatology and Department of Physiological Chemistry, Lu_ad University, Sweden Quantification of cartilage markers released into synovial fluid opens novel possibilities for characterization of joint diseases (Br J Rheumatol 1991; 30: 21-24). To examine the diagnostic value of measuring cartilage markers, a random sample of 2000 people aged 35-55 years (1/3 of all individuals in this age group in a Swedish community) was selected. Using a questionnaire (response rate 92%), 279 persons with knee pain of more than 3 months duration during the preceding year were identified. Of these, 205 agreed to a clinical and

radiographic examination and knee joint aspiration (lavage with 20 ml physiological saline). Sixty-one subjects had grade I osteoarthritis (OA) according to the Ahlbfick radiographic criteria (joint space narrowing). In this group, adequate lavage procedures were possible in 45 individuals. For comparison, 45 age- and sex-matched controls with knee pain but without radiographic changes were selected among the 205 examined individuals. The lavage fluids from these subjects were examined for content of proteoglycan