Effects of T1p Characteristics of Load-Bearing Hip Cartilage on Bilateral Knee Patellar Cartilage Subregions: Subjects With None to Moderate Radiographic Hip Osteoarthritis

Rupsa Bhattacharjee; Rafeek Thahakoya; Johanna Luitjens; Misung Han; Koren E Roach; Fei Jiang; Richard B Souza; Valentina Pedoia; Sharmila Majumdar

doi:10.1002/jmri.29009

Effects of T_1p Characteristics of Load-Bearing Hip Cartilage on Bilateral Knee Patellar Cartilage Subregions: Subjects With None to Moderate Radiographic Hip Osteoarthritis

J Magn Reson Imaging. 2023 Sep 13. doi: 10.1002/jmri.29009. Online ahead of print.

Authors

Affiliations

¹ Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
² Department of Radiology, University Hospital, LMU Munich, Munich, Germany.
³ Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA.
⁴ Department of Physical Therapy and Rehabilitation Science, University of California San Francisco, San Francisco, California, USA.

PMID: 37702305
DOI: 10.1002/jmri.29009

Abstract

Background: The polyarticular nature of Osteoarthritis (OA) tends to manifest in multi-joints. Associations between cartilage health in connected joints can help identify early degeneration and offer the potential for biomechanical intervention. Such associations between hip and knee cartilages remain understudied.

Purpose: To investigate T_1p associations between hip-femoral and acetabular-cartilage subregions with Intra-limb and Inter-limb patellar cartilage; whole and deep-medial (DM), deep-lateral (DL), superficial-medial (SM), superficial-lateral (SL) subregions.

Study type: Prospective.

Subjects: Twenty-eight subjects (age 55.1 ± 12.8 years, 15 females) with none-to-moderate hip-OA while no radiographic knee-OA.

Field strength/sequence: 3-T, bilateral hip, and knee: 3D-proton-density-fat-saturated (PDFS) Cube and Magnetization-Prepared-Angle-Modulated-Partitioned-k-Space-Spoiled-Gradient-Echo-Snapshots (MAPSS).

Assessment: Ages of subjects were categorized into Group-1 (≤40), Group-2 (41-50), Group-3 (51-60), Group-4 (61-70), Group-5 (71-80), and Group-6 (≥81). Hip T_1p maps, co-registered to Cube, underwent an atlas-based algorithm to quantify femoral and acetabular subregional (R₂ -R₇ ) cartilage T_1p . For knee Cube, a combination of V-Net architectures was used to segment the patellar cartilage and subregions (DM, DL, SM, SL). T_1p values were computed from co-registered MAPSS.

Statistical tests: For Intra-and-Inter-limb, 5 optimum predictors out of 13 (Hip subregional T_1p , age group, gender) were selected by univariate linear-regression, to predict outcome (patellar T_1p ). The top five predictors were stepwise added to six linear mixed-effect (LME) models. In all LME models, we assume the data come from the same subject sharing the same random effect. The best-performing models (LME-model_best ) selected via ANOVA, were tested with DM, SM, SL, and DL subregional-mean T_1p . LME assumptions were verified (normality of residuals, random-effects, and posterior-predictive-checks).

Results: LME-model_best (Intra-limb) had significant negative and positive fixed-effects of femoral-R₅ and acetabular-R₂ T_1p , respectively (conditional-R² = 0.581). LME-model_best (Inter-limb) had significant positive fixed-effects of femoral-R₃ T_1p (conditional-R² = 0.26).

Data conclusion: Significant positive and negative T_1p associations were identified between load-bearing hip cartilage-subregions vs. ipsilateral and contralateral patellar cartilages respectively. The effects were localized on medial subregions of Inter-limb, in particular.

Evidence level: 1 TECHNICAL EFFICACY: Stage 1.

Keywords: Osteoarthritis; T1p; bilateral; hip; knee; statistical-modeling.

Abstract

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