BackgroundTo evaluate whether clinical, radiographic or MRI findings are associated with long term risk for total knee arthroplasty (TKA) in persons with knee osteoarthritis.MethodsWe performed a follow-up analysis of 100 persons with knee osteoarthritis who participated in a clinical trial between 2000 and 2002. Clinical data as well as radiography and MRI of the inclusion knee were obtained in all participants. Data on TKA procedures were extracted from The Danish National Patient Register. Clinical, radiographic and MRI findings were analyzed for associations with subsequent TKA.ResultsDuring a mean follow-up period of 15 years, 66% received a TKA in the included knee (target knee); 37% also received a TKA in the other knee. The degree of joint space narrowing was highly associated with subsequent TKA (adjusted odds ratio (OR) 5.0 (95% confidence interval (95% CI) 2.6 – 9.9)) as was a radiological sum score comprising joint space narrowing, osteophytes, subchondral sclerosis and cysts (adjusted OR 1.7 (95% CI 1.3 – 2.1)). MRI detected bone marrow lesions, synovitis and effusion were similarly associated with subsequent TKA with an adjusted OR of 2.3 (95% CI 1.3 – 4.0), 2.8 (95% CI 1.5 – 5.2) and 1.9 (95% CI 1.2 – 3.1), respectively. Increased body mass index (BMI) was not associated with subsequent TKA in the target knee but was associated with TKA in the other knee (OR 2.3 (95% CI 1.2 – 4.3).ConclusionsRadiographic findings including joint space narrowing and MRI detected bone marrow lesions, synovitis and effusion were all significantly associated with the long term risk of TKA in persons with knee osteoarthritis.Electronic supplementary materialThe online version of this article (10.1186/s12891-017-1871-z) contains supplementary material, which is available to authorized users.

EudraCT number: 2012-002607-18.

BackgroundLongitudinal assessment of bone marrow lesions (BMLs) in knee osteoarthritis (KOA) by MRI is usually performed using semi-quantitative grading methods. Quantitative segmentation methods may be more sensitive to detect change over time. The purpose of this study was to evaluate and compare the validity and sensitivity to detect changes of two quantitative MR segmentation methods for measuring BMLs in KOA, one computer assisted (CAS) and one manual (MS) method.MethodsTwenty-two patients with KOA confined to the medial femoro-tibial compartment obtained MRI at baseline and follow-up (median 334 days in between). STIR, T1 and fat saturated T1 post-contrast sequences were obtained using a 1.5 T system. The 44 sagittal STIR sequences were assessed independently by two readers for quantification of BML. The signal intensities (SIs) of the normal bone marrow in the lateral femoral condyles and tibial plateaus were used as threshold values. The volume of bone marrow with SIs exceeding the threshold values (BML) was measured in the medial femoral condyle and tibial plateau and related to the total volume of the condyles/plateaus.The 95% limits of agreement at baseline were used to determine the sensitivity to change.ResultsThe mean threshold values of CAS and MS were almost identical but the absolute and relative BML volumes differed being 1319 mm3/10% and 1828 mm3/15% in the femur and 941 mm3/7% and 2097 mm3/18% in the tibia using CAS and MS, respectively. The BML volumes obtained by CAS and MS were significantly correlated but the tissue changes measured were different. The volume of voxels exceeding the threshold values was measured by CAS whereas MS included intervening voxels with normal SI.The 95% limits of agreement were narrower by CAS than by MS; a significant change of relative BML by CAS was outside the limits of -2.0%-4.7% whereas the limits by MS were -6.9%-8.2%. The BML changed significantly in 13 knees using CAS and in 10 knees by MS.ConclusionCAS was a reliable method for measuring BML and more sensitive to detect changes over time than MS. The BML volumes measured by the two methods differed but were significantly correlated.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-447) contains supplementary material, which is available to authorized users.