Cartilage thickening in early radiographic knee osteoarthritis: A within‐person, between‐knee comparison

Abstract

Objective To determine whether the presence of definite osteophytes (in absence of joint space narrowing [JSN]) by radiograph is associated with (subregional) increases in cartilage thickness, in a within-person, between-knee cross-sectional comparison of participants in the Osteoarthritis Initiative (OAI). Based on previous results, external medial (ecMF) and external lateral weight-bearing femoral (ecLF) subregions were selected as primary endpoints. Methods Both knees of 61 (of 4798) OAI participants displayed definite tibial or femoral marginal osteophytes and no JSN in one knee, and no signs of radiographic OA in the contra-lateral knee; this being confirmed by an expert central reader. In these participants, cartilage thickness was measured in 16 femorotibial subregions of each knee, based on sagittal DESSwe magnetic resonance images. Location-specific joint space width from fixed flexion radiographs was determined using dedicated software. Location-specific associations of osteophytes with cartilage thickness were evaluated using paired t-tests and mixed effect models. Results Of the 61 participants, 48% had only medial, 36% only lateral, and 16% bi-compartmental osteophytes. Osteophyte knees had significantly thicker cartilage than contra-lateral non-osteophyte knees in the ecMF (+71±223μm, equivalent to +5.5%, p=0.015) and ecLF (+64±195μm, +4.1%, p=0.013). No significant differences between knees were noted in other subregions, nor in joint space width. Cartilage thickness in ecMF and ecLF was significantly associated with tibial osteophytes in the same (medial or lateral) compartment (p=0.003). Conclusion Knees with early radiographic OA display thicker cartilage than (contra-lateral) knees without radiographic findings of OA, specifically in the external femoral subregions of compartments with marginal osteophytes.

Imaging research results from the Osteoarthritis Initiative (OAI): a review and lessons learned 10 years after start of enrolment

“…In comparison, OA knees had 10% greater subchondral bone areas,61 and the potentially earliest signs of cartilage thinning in the posterior tibiae, and of cartilage thickening in the external medial femur 61. The latter was confirmed using a between-knee within-person analysis, comparing bilateral knees without JSN, but with and without osteophytes 62. Longitudinally, change in cartilage thickness was more variable in the osteophyte knees 63.…”

“…MRI also provided better discrimination of rates of cartilage loss in different radiographic strata (ie, KLG 2 vs 3, JSN vs no-JSN)65 66 128 and was more sensitive in detecting (regional) cartilage thickening in early radiographic OA62 than fixed location or minimum radiographic JSW. Cross-sectional comparison of contralateral knees with and without JSN revealed side differences in central medial femoral cartilage thickness (r 2 ≈50%) and tibial coverage by the meniscus (r 2 ≈25%) to provide independent information, explaining up to 66% of the variability of minimum and fixed location JSW 129.…”

Thigh muscle cross-sectional areas and strength in knees with early vs knees without radiographic knee osteoarthritis: a between-knee, within-person comparison

“…Participants were drawn from the Osteoarthritis Initiative (OAI) participants (n=4796 http://www.oai-ucsf.edu/datarelease/) (7;8). The inclusion criteria were early RKOA of the tibiofemoral joint (i.e.…”

“…Whereas previous work studied whether reduction in muscle strength (as an independent exposure variable of risk) is associated with the onset or progression of RKOA as an outcome (4–6), the current study focuses on cross-sectional differences in thigh muscle status between knees with an early radiographic stage of knee OA vs. contralateral knees without RKOA (within-person comparison), and on two-year changes in muscle ACSAs (the dependent variable) of knees with and without early RKOA (the independent variable). We considered presence of an osteophyte and absence of JSN as an early stage of RKOA, because cartilage thickness is not yet reduced in these knees (7). We tested the following hypotheses:

Quadriceps ACSAs, strength, and specific strength are lower in knees displaying early RKOA (i.e.

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Associations between Statin use and changes in pain, function and structural progression: a longitudinal study of persons with knee osteoarthritis

“…Yearly knee OA status was measured using validated flexed knee radiographic procedures that have been described extensively 18 19. We used centrally adjudicated KL grades of both knees from the public use data sets.…”