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

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 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 maps, co-registered to Cube, underwent an atlas-based algorithm to quantify femoral and acetabular subregional (R-R) cartilage T. For knee Cube, a combination of V-Net architectures was used to segment the patellar cartilage and subregions (DM, DL, SM, SL). T values were computed from co-registered MAPSS.

STATISTICAL TESTS

For Intra-and-Inter-limb, 5 optimum predictors out of 13 (Hip subregional T, age group, gender) were selected by univariate linear-regression, to predict outcome (patellar T). 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) selected via ANOVA, were tested with DM, SM, SL, and DL subregional-mean T. LME assumptions were verified (normality of residuals, random-effects, and posterior-predictive-checks).

RESULTS

LME-model (Intra-limb) had significant negative and positive fixed-effects of femoral-R and acetabular-R T, respectively (conditional-R = 0.581). LME-model (Inter-limb) had significant positive fixed-effects of femoral-R T (conditional-R = 0.26).

DATA CONCLUSION

Significant positive and negative T 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.