Longitudinal Changes in Magnetic Resonance Imaging–Based Measures of Femorotibial Cartilage Thickness as a Function of Alignment and Obesity: Data From the Osteoarthritis Initiative

Abstract

Objective To investigate the interaction between malalignment and body mass index (BMI) on cartilage thickness change in patients with knee osteoarthritis (OA). Methods 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. Results 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). Conclusion 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.

Patellofemoral alignment and geometry and early signs of osteoarthritis are associated in patellofemoral pain population

“…The association between patella alta and the deterioration of the biochemical composition of cartilage may be explained by the increased contact forces in the PFJ, caused by patella alta . This is in line with other studies which have described a loss of cartilage thickness associated with knee malalignment . Wang et al found higher T1ρ values on the medial anterior femur in OA patients with knee varus .…”

“…39 This is in line with other studies which have described a loss of cartilage thickness associated with knee malalignment. 40 Wang et al found higher T1ρ values on the medial anterior femur in OA patients with knee varus. 41 We suspected lateral and medial patellar translation to have a greater association with lateral and medial trochlear cartilage T1ρ values, respectively.…”

Relationship between alignment and cartilage thickness in patients with non-traumatic and post-traumatic knee osteoarthritis

“…Lower medial plateau cartilage thickness, especially in the central sub-region, in participants with nontraumatic OA compared to healthy controls was not surprising, and is supported by previous researh. 15 There was lower medial plateau cartilage thickness in participants with non-traumatic compared to post-traumatic knee OA. This finding was inconsistent with previous studies, 3,4 although differences did not remain in controlled analyses.…”

“…There is a substantial amount of unexplained variance; although, these values are similar to another study (R 2 ¼ 14e22%) that investigated the association of body mass index and knee alignment with cartilage thickness loss over 2 years in patients with knee OA. 15 In addition, the interaction between OA group and MAA significantly explained the variance in lateral condyle cartilage thickness. The relationship between MAA and lateral condyle cartilage thickness was stronger in the non-traumatic than the post-traumatic OA group.…”

The morphology of proximal tibiofibular joint (PTFJ) predicts incident radiographic osteoarthritis: data from Osteoarthritis Initiative

“…Wang et al 10 revealed increased medial joint space and improved axial alignment of the lower extremity after PFO, especially in those with severe genu varus. Despite many potential mechanisms for MTF OA being investigated, such as dynamic load 11 , obesity 12 , knee adduction moment 13 , malalignment of the knee 12 and toe-out angle 14 , the relationship between proximal tibiofibular joint (PTFJ) and tibiofemoral (TF) OA has been rarely studied 15 .…”