Article

Different methods have been used to classify
osteoarthritis (OA) of the hip. We evaluated the reliability of different
classifications in order to find which grading system is most appropriate for use
in clinical practice. METHODS: 49 patients (61 affected hips)
with late-detected developmental dislocation of the hip (DDH) were studied. The mean
age at follow-up was 45 (32-49) years. 3 classifications of OA were compared. The
gradings by Kellgren and Lawrence (1957) (K&L) and Croft et al. (1990) are global
visual assessments based on osteophytes, cysts, subchondral sclerosis, and
narrowing of the joint space. The third classification is based on narrowing in
the upper, weight-bearing part of the joint and defines as OA a minimum joint
space width (JSW) of less than 2.0 mm at the narrowest part. 2 experienced
observers, one radiologist and one orthopedic surgeon, assessed and measured the
radiographs. RESULTS: Minimum JSW (< 2.0 mm in 9 hips) gave the best
inter-observer agreement (kappa value = 0.87). Using the K&L grading,
inter-observer agreement was moderate (kappa = 0.55), but kappa increased when
the number of categories was reduced from 5 to 3 (no OA, mild OA, and severe OA).
The Croft classification gave similar agreement as the K&L grading. The
intra-observer agreement was better than inter-observer agreement, irrespective
of the grading system. There was a good accordance between the minimum JSW and
the 2 other methods. INTERPRETATION: Joint space narrowing using a minimum JSW of < 2.0 mm as criterion for OA was the simplest and most reproducible
classification in long-term follow-up of patients with DDH.
A classification
based on global visual assessment can be used in addition if only hips with
severe OA are included.

Langue : ANGLAIS