Stine Hangaard1,2, Mikael Boesen3, Henning Bliddal4, Wolfgang Wirth5,6. 1. The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark. stine.hangaard@regionh.dk. 2. Department of Radiology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark. stine.hangaard@regionh.dk. 3. Department of Radiology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark. 4. The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark. 5. Institute of Anatomy and Musculoskeletal Research, Paracelsus Medical University, Salzburg, Austria. 6. Chondrometrics GmbH, Ainring, Germany.
Abstract
OBJECTIVE: Kellgren-Lawrence grades (KLG) are frequently used for patient selection in clinical trials. The Ahlbäck radiographic grading system has been developed for moderate and severe knee OA. KLG 3 is comparable to Ahlbäck 1 and KLG 4 is subdivided into Ahlbäck 2-5. The objective of this study was to investigate if the Ahlbäck scoring system is able to subdivide patients with moderate to severe knee OA (KLG 3/4) into groups with different sensitivity to change in cartilage thickness. MATERIALS AND METHODS: This study was based on 108 Osteoarthritis Initiative (OAI) participants with KLG 3/4. Baseline KLG scores were available from the OAI database; Ahlbäck scores were performed using the same x-rays. Cartilage thickness change in the weight-bearing femorotibial cartilage was analysed from baseline and year 1 3D FLASH MRI for the entire femorotibial joint (FTJ), the medial (MFTC) and the lateral compartment (LFTC) and for the location-independent ordered values 1 and 16 (OV 1/OV 16) representing the subregions with largest loss (OV 1) and gain (OV 16) within each knee. RESULTS: Of the 108 patients, n = 30/78 had KLG 3/4. The corresponding Ahlbäck scores (1-5) were n = 30/33/36/9/10. Cartilage thickness changes between Ahlbäck groups showed no statistically significant difference for FTJ, MFTC, LFTC and OV 1, but change in OV 16 was significantly higher in Ahlbäck 4 knees (p = 0.03) compared to Ahlbäck 1-3 knees. CONCLUSION: Radiographic knee OA grading with Ahlbäck scores was not superior to KLG for prediction of cartilage thickness loss over 1 year, in patients with moderate and severe knee OA supporting the continuous use of the easier and more widely used KLG.
OBJECTIVE: Kellgren-Lawrence grades (KLG) are frequently used for patient selection in clinical trials. The Ahlbäck radiographic grading system has been developed for moderate and severe knee OA. KLG 3 is comparable to Ahlbäck 1 and KLG 4 is subdivided into Ahlbäck 2-5. The objective of this study was to investigate if the Ahlbäck scoring system is able to subdivide patients with moderate to severe knee OA (KLG 3/4) into groups with different sensitivity to change in cartilage thickness. MATERIALS AND METHODS: This study was based on 108 Osteoarthritis Initiative (OAI) participants with KLG 3/4. Baseline KLG scores were available from the OAI database; Ahlbäck scores were performed using the same x-rays. Cartilage thickness change in the weight-bearing femorotibial cartilage was analysed from baseline and year 1 3D FLASH MRI for the entire femorotibial joint (FTJ), the medial (MFTC) and the lateral compartment (LFTC) and for the location-independent ordered values 1 and 16 (OV 1/OV 16) representing the subregions with largest loss (OV 1) and gain (OV 16) within each knee. RESULTS: Of the 108 patients, n = 30/78 had KLG 3/4. The corresponding Ahlbäck scores (1-5) were n = 30/33/36/9/10. Cartilage thickness changes between Ahlbäck groups showed no statistically significant difference for FTJ, MFTC, LFTC and OV 1, but change in OV 16 was significantly higher in Ahlbäck 4 knees (p = 0.03) compared to Ahlbäck 1-3 knees. CONCLUSION: Radiographic knee OA grading with Ahlbäck scores was not superior to KLG for prediction of cartilage thickness loss over 1 year, in patients with moderate and severe knee OA supporting the continuous use of the easier and more widely used KLG.