Disclosures: Andrew M. Hiett, MD: No financial relationships or conflicts of interest

Objective: Compare the concurrent validity of change in 3D-joint space width (JSW) from weight-bearing computed tomography (WBCT) vs. change in 2D-JSW on radiographs for structural worsening of tibiofemoral osteoarthritis assessed by radiographs and MRI

Design: Radiographs, WBCT, and MRI were acquired at baseline and 24-month follow-up for 340 knees in 263 participants from the Multicenter Osteoarthritis Study (MOST). Radiographs were evaluated for change in 2D-JSW at predetermined locations, as well as for Osteoarthritis Research Society International (OARSI) joint space narrowing (JSN) grades. WBCT scans were evaluated for change in JSW at defined locations on the articular surface. MRI scans were assessed using MRI Osteoarthritis of the Knee Score for cartilage morphology (MOAKS-CM). Concurrent validity was defined by the associations of JSW change on radiographs and WBCT with structural worsening on radiographs (OARSI JSN) and MRI (MOAKS-CM) using logistic regression.

Setting: Community based observational study of adults in Iowa City, Iowa and Birmingham, Alabama

Participants: 263 participants of community-based cohort from the Multicenter Osteoarthritis Study (MOST)

Interventions: None

Main Outcome Measures: Change in OARSI JSN score, Change in MOAKS-CM score, Change in 2D-JSW, Change in 3D-JSW

Results: Mean ± SD age was 63.2±9.0 years, BMI was 28.2±4.9 kg/m2, 57% were women and 23% knees had KL Grade 2-3 at baseline. For worsening OARSI JSN, change in Mean 3D-JSW (AUROC=0.745) and maximum change in 3D-JSW (AUROC=0.747) did not provide significantly different concurrent validity than 2D-JSW (AUROC=0.808). For worsening medial MOAKS-CM, change in Mean 3D-JSW (AUROC=0.681) and Maximum change in 3D-JSW(AUROC=0.682) were not superior to 2D-JSW (AUROC=0.713). This was also the case for lateral MOAKS-CM, (AUROC=0.757), (AUROC=0.730), respectively, and 2D-JSW(AUROC=0.695).

Conclusions: Changes in 3D JSW did not provide greater concurrent validity with changes in OARSI JSN or MOAKS-CM over 24 months than change in 2D-JSW in a patient population predominantly without radiographic osteoarthritis.

Level of Evidence: Level II

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/concurrent-validity-of-change-in-joint-space-width-with-knee-osteoarthritis-structural-worsening-over-24-months-comparison-of-3d-jsw-on-weight-bearing-ct-vs-2d-jsw-on-radiographs/