Body Mass Index (BMI) and Varus Malalignment Compound to Define a High-Risk Phenotype for Compartment-Specific Knee Osteoarthritis Progression
Authors' conclusion
BMI and lower limb alignment influence structural KOA progression through compartment-specific pathways. The compounding interaction in the medial compartment identifies high BMI combined with varus malalignment as a high-risk phenotype for medial structural progression.
Study context
- Population
- Participants in the Osteoarthritis Initiative followed over 0–60 monthsparticipants, 5,930 limbs analyzed
- Participants
- 3,191 participants
- Outcome
- Medial compartment cartilage thickness change, BMI x varus alignment interaction
Methodological detailslinear mixed-effects models, logistic regression with participant-clustered standard errors, adjusted for age, sex, and baseline Kellgren-Lawrence grade
- Linear mixed-effects models
- Logistic regression with participant-clustered standard errors
- Adjusted for age, sex, and baseline Kellgren-Lawrence grade
Main finding
As reported in the abstract
Femur: β per 1-SD BMI x 1-SD hip-knee-ankle (HKA) (95% CI [0.0001, 0.0031])
0.0016 mm/year
Tibia: β (95% CI [0.0008, 0.0028])
0.0018
Observational data: associations, not effects.
Further findings
Lateral compartment cartilage loss, nonlinear alignment association (time x HKA2)
- Femur β (95% CI [−0.0038, −0.0027])
- −0.0032 mm/year
- Tibia β (95% CI [−0.0040, −0.0026])
- −0.0033
- Alignment, but not BMI, was associated with faster cartilage loss
Total knee replacement (TKR) odds per 1-degree greater absolute HKA deviation from the radiographically healthy reference angle (−1.0°) · five and ten years
- Five years, fold increase (95% CI [1.04, 1.18])
- 1.11
- Ten years, fold increase (95% CI [1.08, 1.21])
- 1.14
- BMI did not modify the association between HKA deviation and TKR
Original publication
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