Entheseal bone remodeling and patient reported outcomes in osteoarthritis - A quantitative [18F]NaF-PET MRI study

Entheses have been discussed as potential sources of pain in osteoarthritis (OA). Entheseal bone remodeling quantified by [18F]NaF-PET could be a surrogate marker for tensile forces causing a painful tissue response. This study aimed to investigate the relationship between [18 F]NaF-uptake, MRI findings and knee-related symptoms.

Patients and healthy controls in this prospective observational study on patello-femoral OA (PFJOA) underwent simultaneous MR (at 3.0 T) and [18F]NaF PET imaging of both knees. Cartilage damage, subchondral marrow lesions, synovitis, and enthesophytes were semi-quantitatively assessed on MRI and entheseal tracer uptake was quantified in the anterior patella and tibial tuberosity. Symptoms were assessed with the Knee injury and Osteoarthritis Outcome Score (KOOS). Generalized estimating equations were used to investigate associations between tracer uptake and symptoms; analyses were additionally adjusted for MRI-detected changes (as alternative symptom drivers), age, sex and body mass index.

A total of 135 knees from 68 subjects were investigated (mean age 48.8 ± 10.4 years; 58.8% women). Higher [18F]NaF-uptake was significantly associated with worse outcomes for KOOS subscales sports (beta -2.7; p<0.001), quality of live (beta 3.0; p<0.001) and PFJ (beta 2.3; p=0.001), but not pain (beta -0.8; p=0.18), symptoms (beta -0.6; p=0.30) or activities of daily living (beta -1.1; p=0.06).

Entheseal bone remodeling quantified by [18F]NaF-PET-MRI is associated with patient-reported clinical knee outcomes. These findings underscore the potential of entheseal biology to inform the understanding of symptom generation in degenerative disease of the musculoskeletal system.