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J Rheumatol. 1996 Oct;23(10):1749-55.

Assessment of joint space width in patients with osteoarthritis of the knee: a comparison of 4 measuring instruments.

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  • 1Clinique de Rhumatologie, Hôpital Cochin, Paris, France.

Abstract

OBJECTIVE:

To evaluate the intra and interobserver reproducibility of 4 measuring instruments for assessing joint space width in knee osteoarthritis (OA) and to estimate the effects of patients, instrument, session order, and reader variation.

METHODS:

We studied 30 patients with unilateral tibiofemoral OA selected to represent a broad range of radiographic changes. Joint space width (JSW) was measured on plain anteroposterior weight bearing radiographs. Using an experimental design, 3 readers assessed JSW 3 times with 4 measuring instruments (ruler, caliper, graduated magnifying glass, digitized assessment).

RESULTS:

Intra and interobserver reproducibility was high with all measuring instruments (intraclass correlation coefficients from 0.95 to 0.98 and from 0.91 to 0.97, respectively). Analysis of variance (ANOVA) showed a patient effect (p < 10(-6)), a reader effect (p = 0.0001), an instrument effect (p = 0.0001), and a session order effect (p = 0.04). The variance component estimates were patients 55%, readers 34%, session order 2%, instruments 8%. ANOVA performed separately for each instrument showed that session order differences always represented less than 1% of the total variance. The reader component accounted for 0% of the total variance for the ruler, 2% for the digitized method, 16% for the caliper, and 18% for the graduated magnifying glass.

CONCLUSION:

Ruler and digitized assessment have better reliability than caliper and graduated magnifying glass.

PMID:
8895153
[PubMed - indexed for MEDLINE]
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