External hip adduction moment and progression of medial tibiofemoral cartilage damage and bone marrow lesions in persons with knee osteoarthritis

Abstract

Purpose: Gait biomechanics at the hip may affect medial joint loading at the knee in persons with knee osteoarthritis (OA). A greater external hip adduction moment (reflecting torque generation by the hip abductor muscles) during the stance phase of gait may limit excessive hip drop or trunk lean. This, in turn, may prevent excessive medial knee joint loading and eventual progression of knee OA. Little is known about the relationship between the external hip adduction moment and progression of medial tibiofemoral OA as assessed by MRI. We hypothesized that a greater magnitude of the baseline external hip adduction moment is associated with reduced risk of baseline-to-2-year progression of medial tibiofemoral cartilage damage and bone marrow lesions in persons with knee OA. Methods: Participants with knee OA, defined by osteophyte presence in at least one knee, underwent quantitative gait analysis at baseline using an 8-camera Digital Real-Time Eagle motion analysis system and force plate. Inverse dynamics were used to calculate the external hip adduction moment, normalized to %bodyweight*height. Both knees underwent 3.0T MRI at baseline and two year follow-up using double oblique coronal and axial FLASHwe, coronal T1-weighted spin-echo (SE), and sagittal, axial and coronal fat-suppressed turbo spin echo sequences. We assessed cartilage damage and bone marrow lesions using WORMS scoring, blinding readers to hypotheses and all other data. We used logistic regression statistical models with generalized estimating equations (GEE) to account for correlation between the 2 limbs of each person, to assess the association between external hip adduction moment at baseline and baseline-to-2-year cartilage damage progression and bone marrow lesion progression, defined as any worsening of score in the medial compartment as a whole and within each joint surface. Analyses were adjusted for gait speed, age, gender, and disease severity (using K/L radiographic grade). Results are reported as odds ratios (ORs) and 95% confidence intervals (CIs). Results: 204 persons [mean age 64.2 years (±9.9, SD), mean BMI 28.5 kg/m2 (±5.7), 76.5% women] contributing 391 knees comprised the study sample. The mean external hip adduction moment was 4.43 (±0.9, SD) %body weight*height. As shown in Table 1, a greater external hip adduction moment was significantly associated with a reduced likelihood of cartilage damage progression in the medial tibiofemoral compartment and also at the medial femoral surface. After adjustment for the indicated covariables, these associations were no longer statistically significant at the 5% level. Table 2 shows the means (±SD) of the external hip adduction moment at baseline for knees with and without cartilage damage and bone marrow lesion progression in specific subregions. In analyses of specific regions, a greater external hip adduction moment was significantly associated with a reduced likelihood of cartilage damage progression at the posterior femoral subregion [OR per 1 unit of external hip adduction moment (95% CI): 0.51 (0.31, 0.86)] and bone marrow lesion progression at the central femoral subregion [OR per 1 unit (95% CI): 0.56 (0.35, 0.89)]. Conclusions: In persons with knee osteoarthritis, a greater external hip adduction moment was associated with a reduced likelihood of 2-year medial tibiofemoral cartilage damage progression and bone marrow lesion progression, but these findings were no longer statistically significant in adjusted analyses. The consistently protective direction of the findings at compartment, joint surface, and subregional levels warrants further evaluation at longer follow-up.Table 1Unadjusted and adjusted ORs (95% CIs) for medial tibiofemoral OA progression at 2 yearsMedial Tibiofemoral CompartmentMedial Femoral SurfaceMedial Tibial SurfaceCartilage damage progressionBone marrow lesion progressionCartilage damage progressionBone marrow lesion progressionCartilage damage progressionBone marrow lesion progressionNumber of knees (%) with progression61/391 (16%)87/391 (22%)48/391 (12%)53/391 (14%)29/391 (7%)48/391 (12%)Baseline predictorExternal Hip Adduction Moment (%BW*HT)Unadjusted0.70 (0.51, 0.97)0.75 (0.55, 1.01)0.68 (0.50, 0.93)0.72 (0.48, 1.08)0.88 (0.59, 1.32)0.96 (0.67, 1.37)Adjusted*0.82 (0.58, 1.15)0.85 (0.61, 1.17)0.79 (0.56, 1.12)0.80 (0.53, 1.21)1.07 (0.70, 1.64)1.20 (0.83, 1.75)Results are per 1 unit (%BW*HT) of external hip adduction moment (n = 391 knees from 204 persons)*adjusted for gait speed, age, gender, and K/L grade Open table in a new tab Table 2Means (SD) for the external hip adduction moment in medial tibial and femoral subregionsExternal Hip Adduction Moment (%BW*HT), mean (SD)Cartilage damage progression at 2-year follow-upPosterior femurCentral femurPosterior tibiaCentral tibiaAnterior tibiaNumber of knees (%) with progression20/391 (5%)33/391 (8%)7/391 (2%)25/391 (6%)8/391 (2%)Knees without progression, mean (SD)4.45 (0.88)4.44 (0.90)4.43 (0.89)4.43 (0.89)4.43 (0.89)Knees with progression, mean (SD)3.97 (0.85)4.36 (0.67)3.98 (0.57)4.32 (0.79)4.61 (0.87)Bone marrow lesion progression at 2-year follow-upNumber of knees (%) with progression19/391 (5%)38/391 (10%)12/391 (3%)33/391 (8%)21/391 (5%)Knees without progression, mean (SD)4.43 (0.87)4.47 (0.87)4.43 (0.89)4.44 (0.89)4.43 (0.88)Knees with progression, mean (SD)4.38 (1.19)4.05 (0.92)4.38 (0.84)4.34 (0.79)4.52 (0.96) Open table in a new tab Results are per 1 unit (%BW*HT) of external hip adduction moment (n = 391 knees from 204 persons) *adjusted for gait speed, age, gender, and K/L grade