Moyer Rebecca, Wirth Wolfgang, Eckstein Felix
Rebecca Moyer, PT, PhD: Dalhousie University, Halifax, Nova Scotia, Canada.
Institute of Anatomy, Paracelsus Medical University Salzburg & Nuremberg, Salzburg, Austria, and Chondrometrics GmbH, Ainring, Germany.
Arthritis Care Res (Hoboken). 2017 Jul;69(7):959-965. doi: 10.1002/acr.23096. Epub 2017 Jun 7.
To investigate the interaction between malalignment and body mass index (BMI) on cartilage thickness change in patients with knee osteoarthritis (OA).
Femorotibial cartilage thickness was measured from baseline to 2 years in 558 knees with radiographic OA. Cartilage thickness was determined in the central weight-bearing medial femorotibial cartilage (cMFTC) and lateral (cLFTC) compartments. Femorotibial angle (FTA) was stratified into neutral, minor, and definite malalignment. BMI was stratified using World Health Organization classifications for normal, overweight, and obese. Multivariable linear regression models were used to investigate the interaction between alignment and BMI, adjusting for age, sex, and disease severity.
There was no significant interaction for continuous measures of alignment and BMI (P = 0.301 for cMFTC and P = 0.852 for cLFTC). Using BMI tertiles, the association between alignment and medial or lateral cartilage thickness loss was not moderated by BMI, despite a significant association of malalignment with greater cartilage thickness loss (P ≤ 0.005). Using FTA tertiles, the association between BMI and medial cartilage thickness loss was approximately 3 times greater in knees with definite malalignment (P = 0.149) and approximately 5 times greater in knees with minor malalignment (P = 0.006). Specifically, knees with minor varus significantly modified this relationship (P = 0.021).
Malalignment was significantly associated with cartilage thickness loss per degree increase in malalignment, but was not moderated by BMI. BMI was significantly associated with greater rates of medial cartilage thickness loss per unit increase in BMI but only in knees with minor varus malalignment. These findings have implications for better understanding patient subgroups and intervention strategies targeting risk factors for knee OA.
探讨膝关节骨关节炎（OA）患者中力线不良与体重指数（BMI）对软骨厚度变化的相互作用。
对558例有影像学OA的膝关节从基线到2年进行股胫软骨厚度测量。在中央负重的内侧股胫软骨（cMFTC）和外侧（cLFTC）间室测定软骨厚度。将股胫角（FTA）分为中立、轻度和明显力线不良。BMI根据世界卫生组织的分类分为正常、超重和肥胖。使用多变量线性回归模型研究力线和BMI之间的相互作用，并对年龄、性别和疾病严重程度进行校正。
力线和BMI的连续测量之间没有显著的相互作用（cMFTC的P = 0.301，cLFTC的P = 0.852）。使用BMI三分位数，尽管力线不良与更大的软骨厚度损失显著相关（P≤0.005），但力线与内侧或外侧软骨厚度损失之间的关联并未因BMI而受到调节。使用FTA三分位数，在明显力线不良的膝关节中，BMI与内侧软骨厚度损失之间的关联大约大三倍（P = 0.149），在轻度力线不良的膝关节中大约大五倍（P = 0.006）。具体而言，轻度内翻的膝关节显著改变了这种关系（P = 0.021）。
力线不良每增加一度与软骨厚度损失显著相关，但不受BMI调节。BMI每单位增加与内侧软骨厚度损失率显著增加相关，但仅在轻度内翻力线不良的膝关节中如此。这些发现有助于更好地理解患者亚组以及针对膝关节OA危险因素的干预策略。
