Abstract
BackgroundPatients are susceptible for knee osteoarthritis (KOA) with increasing age and obesity and KOA is expected to become a major disabling disease in the future. An important feature of KOA on magnetic resonance imaging (MRI) is changes in the subchondral bone, bone marrow lesions (BMLs), which are related to the future degeneration of the knee joint as well as prevalent clinical symptoms. The aim of this study was to investigate the changes in BMLs after a 16-week weight-loss period in obese subjects with KOA and relate changes in BMLs to the effects of weight-loss on clinical symptoms.MethodsThis prospective cohort study included patients with a body mass index ≥ 30 kg/m2, an age ≥ 50 years and primary KOA. Patients underwent a 16 weeks supervised diet program which included formula products and dietetic counselling (ClinicalTrials.gov: NCT00655941). BMLs in tibia and femur were assessed on MRI before and after the weight-loss using the Boston-Leeds Osteoarthritis Knee Score. Response to weight-loss in BML scores was dichotomised to patients experiencing a decrease in BML scores (responders) and patients who did not (non-responders). The association of BMLs to weight-loss was assessed by logistic regressions and correlation analyses.Results39 patients (23%) were classified as responders in the sum of all BML size scores whereas 130 patients (77%) deteriorated or remained stable and were categorized as non-responders. Logistic regression analyses revealed no association between weight-loss < or ≥ 10% and response in BMLs in the most affected compartment (OR 1.86 [CI 0.66 to 5.26, p=0.24]). There was no association between weight-loss and response in maximum BML score (OR 1.13 [CI 0.39 to 3.28, p=0.81]). The relationship between changes in BMLs and clinical symptoms revealed that an equal proportion of patients classified as BML responders and non-responders experienced an OMERACT-OARSI response (69 vs. 71%, p=0.86).ConclusionsWeight-loss did not improve the sum of tibiofemoral BML size scores or the maximum tibiofemoral BML score, suggesting that BMLs do not respond to a rapidly decreased body weight. The missing relationship between clinical symptoms and BMLs calls for further investigation.
Highlights
Patients are susceptible for knee osteoarthritis (KOA) with increasing age and obesity and KOA is expected to become a major disabling disease in the future
The incidence of obesity has steadily increased over the past decades and combined with the fact that patients are susceptible for knee osteoarthritis (KOA) with increasing age and obesity KOA is expected to become a major disabling disease in the future [1,2,3]
The study included 192 obese KOA patients and following the 16 weeks of diet intervention 175 (%) patients remained in the study. 187 (97%) magnetic resonance imaging (MRI) scans were completed at baseline, 172 (98%) MRI scans were obtained at week 16 and this left the study with 169 (97%) patients with complete MRI datasets
Summary
Patients are susceptible for knee osteoarthritis (KOA) with increasing age and obesity and KOA is expected to become a major disabling disease in the future. An important feature of KOA on magnetic resonance imaging (MRI) is changes in the subchondral bone, bone marrow lesions (BMLs), which are related to the future degeneration of the knee joint as well as prevalent clinical symptoms. The incidence of obesity has steadily increased over the past decades and combined with the fact that patients are susceptible for knee osteoarthritis (KOA) with increasing age and obesity KOA is expected to become a major disabling disease in the future [1,2,3]. It is highly relevant to examine the effect of weight-loss in obese KOA patients as this modifiable factor could have an effect on KOA-related structural changes, as assessed by magnetic resonance imaging (MRI). BMLs have been associated to the future degeneration of the joint in KOA, prevalent clinical symptoms and malalignment by means of an increased mechanical load [13,18,19,20,21]
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