Ahlback grading of osteoarthritis of the knee: poor reproducibility and validity based on visual inspection of the joint

• BACKGROUND: Staging of osteoarthritis (OA) of the knee is commonly based on the Ahlback classification. Its value has been questioned, however. We therefore evaluated the reproducibility and validity of this classification of knee osteoarthritis. PATIENTS AND METHODS: 48 patients (48 knees) (medial OA: n = 30; lateral OA: n = 8) operated with total knee prostheses were studied. Weight-bearing radiographs were evaluated twice by 4 observers. Presence of bone attrition on radiographs was compared with observations of the resected parts of the distal femur and proximal tibia. RESULTS: When the same observer classified the radio-graphs twice according to Ahlback, the repeatability was fair in both medial OA (kappa values = 0.15-0.65) and lateral OA (0.59-0.76), and between different observers it was poor (kappa: 0.1). Comparison between radiographic classification and classification based on visual inspection of the bone pieces removed during arthroplasty revealed an acceptable sensitivity in both medial (67-95%) and lateral OA (43-86%), but the specificity was low (medial: 11-67%; lateral: 25-75%). INTERPRETATION: The main problem with the Ahlback classification was that a joint space could often be seen radiographically despite the presence of bone attrition on the preparations. According to our study, conventional radiographs do not give sufficient information for correct grading.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kirurgi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Surgery (hsv//eng)

Nyckelord

Aged

Aged

80 and over

Female

Humans

Knee Joint/*radiography

Male

Middle Aged

Observer Variation

Osteoarthritis

Knee/classification/*radiography/surgery

Reproducibility of Results

Sensitivity and Specificity

Weight-Bearing

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)