Ridges and grooves on the bony surfaces of osteoarthritic joints

Osteoarthritis and Cartilage Vol. 1 No. 1

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Genetic l i n k a g e and clinical analysis of patients with hereditary arthroo p h t h a l m o p a t h y (Stickler s y n d r o m e ) A. RAI*, P. FARNDON~, M . KILPATRICK~, T. J . FEATHERSTONt AND G. STRUTHERS*

*Department of Rheumatology, tOphthalmology, Coventry $Clinical Genetics Department, Birmingham, U.K. H e r e d i t a r y a r t h r o - o p t h a l m o p a t h y (AO) is a n a u t o s o m a l d o m i n a n t d i s o r d e r of c o n n e c t i v e tissue c h r a c t e r i z e d by a n u m b e r of v a r i a b l e f e a t u r e s w h i c h i n c l u d e v i t r e o r e t i n a l d e g e n e r a t i o n , r e t i n a l d e t a c h m e n t a n d p r e m a t u r e OA. We performed a g e n e t i c l i n k a g e s t u d y u s i n g R F L P ( r e s t r i c t i o n f r a g m e n t l e n g t h p o l y m o r p h i s m ) m a r k e r s for t h e COL2A1 gene (which encodes type II collagen) in two families. In t o t a l 17 affected i n d i v i d u a l s were noted, 13 b e i n g alive. C l i n i c a l a s s e s s m e n t of family n u m b e r s was s u p p o r t e d by a full o p h t h a l m o l o g i c a l e x a m i n a t i o n w h e r e indicated. C l i n i c a l d e t a i l s were a n a l y z e d retrosp e c t i v e l y to assess a n y f e a t u r e s t h a t m a y p r e d i c t t h e o u t c o m e of p r e m a t u r e OA. L i n k a g e was found b e t w e e n t h e COL2A1 gene a n d AO

in one family: m a x i m u m LOD score of 2.533 was o b t a i n e d at a r e c o m b i n a t i o n f r a c t i o n of zero. The o b s e r v a t i o n provides evidence t h a t in this f a m i l y pedigree t h e m u t a t i o n c a u s i n g a r t h r o - o p h t h a l m o p a t h y affects t h e s t r u c t u r a l locus for t y p e II collagen. The m a r k e r s used were n o n i n f o r m a t i v e in t h e s e c o n d f a m i l y a n d h e n c e f u r t h e r a n a l y s i s u s i n g o t h e r R F L P m a r k e r s is necessary. P r e m a t u r e h i p OA was n o t e d in t h r e e cases. T h e m e a n age a t hip r e p l a c e m e n t was 48 years. The p r e s e n c e of specific e a r l i e r o c c u l a r f e a t u r e s (e.g. myopia, r e t i n a l d e t a c h m e n t a n d v i t r o u s changes) did n o t p r e d i c t t h e o u t c o m e of OA. H y p e r m o b i l i t y was noted in t h e y o u n g e r g e n e r a t i o n s in some cases a n d m a y be of significance.

Ridges and g r o o v e s on the bony surfaces of o s t e o a r t h r i t i c joints JULIET ROGERS, GERRY BARBER, PAUL DIEPPE AND JOHN KIRWAN

Bristol University Department of Medicine, Rheumatology Unit, Bristol Royal Infirmary, Bristol U.K. O s t e o a r t h r i t i s (OA) is a s s o c i a t e d w i t h d i s r u p t i o n of the a r t i c u l a r c a r t i l a g e , c a u s i n g fibrillation and p i t t i n g of t h e j o i n t surface. The m a c r o s c o p i c c h a n g e s seen on t h e surface of the u n d e r l y i n g bone have received little attention. In a l a r g e collection of p a l e o p a t h o l o g i c a l skeletons, we h a v e often observed deep p a r a l l e l ridges and grooves of t h e s u b c h o n d r a l e b u r n a t e d bone, p a r t i c u l a r l y to the patello-femoral joint. We h a v e also seen the same phenom e n o n in a small n u m b e r of c o n t e m p o r a r y bones t r e a t e d to remove all soft tissue. T h r e e such specimens h a v e been examined in detail,

and the c h a r a c t e r i s t i c s of the ridges d o c u m e n t e d by reflex microscopy. The d e p t h of grooves v a r i e d from 0.5-5.5 ram, with a peak-to-peak d i s t a n c e r a n g i n g from 1-4 mm. In each case t h e r e was precise m a t c h i n g of ridges a n d grooves on t h e two sides of t h e joint, so t h a t t h e surfaces fit t o g e t h e r like a gear, and confine movem e n t of t h e j o i n t to one plane. This p r e v i o u s l y u n d o c u m e n t e d a s p e c t of t h e b o n e response of OA m a y h a v e significance to the j u n c t i o n and outcome of an o s t e o a r t h r i t i c joint. The o b s e r v a t i o n s r a i s e f u r t h e r questions as to t h e c o n t r o l and f u n c t i o n of s u b c h o n d r a l bone c h a n g e s in OA.

EPIDEMIOLOGY Radiographic c h a n g e s in the hands of rock climbers S. R. BOLLEN AND V. WRIGHT

University of Leeds, Leeds, U.K. Rock climbing is a s p o r t t h a t h a d u n d e r g o n e a revolution in s t a n d a r d s of difficulty over t h e l a s t 15 years. A t top s t a n d a r d s , finger holds m a y be as t h i n as a m a t c h stick and c o n s e q u e n t l y e n o r m o u s s t r a i n s a r e p l a c e d on the fingers. A study to see if these produce r a d i o g r a p h i c changes in the p h a l a n g e s a n d i n t e r p h a l a n g e a l j o i n t s was c a r r i e d out on 36 male r o c k climbers (median age 31 years, r a n g e 20-50 years). T h e y were e i t h e r the 'elite' of British climbing (including t h r e e out of four of the British climbing team) or were climbing a t a less severe

grade, b u t h a d done so for m a n y years. Case c o n t r o l s were provided by h a n d X-rays from the A & E D e p a r t m e n t . Using a V e r n i e r c a l i p e r t h e p e r c e n t a g e of c o r t i c a l t h i c k n e s s of t o t a l width was c a l c u l a t e d in t h e p r o x i m a l p h a l a n x (pp) and middle p h a l a n x (mp) of the r i g h t middle finger. The mean c o r t i c a l t h i c k n e s s of pp a n d mp in climbers was 70% and 74%, c o m p a r e d w i t h 58% and 62~o in controls ( P < 0.01). S u b c h o n d r a l cysts were found in t h e h a n d s of 17 climbers c o m p a r e d with only two of t h e