AMSTERDAM, The Netherlands – Hand osteoarthritis (OA) research and care urgently needs better radiographic standards that include validated criteria for assessing changes in small joints, better ways to differentiate OA from other changes, and an understanding that the OA disease process includes repair as well as degradation, Iain Watt, FRCR, FRCP, said at the EULAR 2006 meeting.¹

"The need for a carefully evaluated study to establish precision, and especially smallest detectable difference, is overdue. Perhaps the two more basic questions are, how do we distinguish osteoarthritis from simple aging, and can we evaluate features of joint repair and failure (and if so, quantitate them)?" asked Dr. Watt, who is in the Department of Radiology at Leiden University Medical Center, Leiden, The Netherlands. Dr. Watt reviewed the strengths and weaknesses of major radiographic grading systems in hand OA, including Kellgren and Lawrence² , Kallman et al³, Altman et al⁴, and Verbruggen and Veys⁵. He classified the current approaches as

• stamp collecting,
• spot the difference,
• phases of the moon, and
• all-or-nothing.

Dr. Watt said that Kellgren and Lawrence is "a form of stamp collecting" because it relies matches between the patients radiographs and an atlas. "This is the best fast approach, but it assumes a uniform disease process, that stage 1 patients progress to stage 2 in an orderly say," he said.

"Spot the difference" is the basis of the Kallman et al and Altman et al indices. "These are an improvement on global scores and allow analysis of specific features, but they still require stamp collecting. They allow for change in specific features but cannot cope with erosive OA and do not account for healing and repair," he said.

Verbruggen and Veys developed a "phases of the moon" approach that recognizes that OA includes repair as well as degradation. "There is a natural cycle of degradation and reconstitution of the articular surface," Dr. Watt said. However, this method cannot foretell outcomes for individual patients.

Kessler et al is "all or nothing" approach. "Joint space narrowing (JSN) is the most important element in this index. It does not look at disease phase, but it is simple, quick, and highly reliable," Dr. Watt said.

He added that comparison studies of the different systems have not identified any one as clearly superior. "The questions is why there is such a rotten correlation between clinical features and radiological features in OA," Dr. Watt said. Other unanswered questions are which joints to look at, and how much importance to assign to joint space narrowing.

"So far, some form of 'spot the difference' and 'phases of the moon' is the best buy," Dr. Watt concluded.

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