Acute Cartilage Loading Responses After an In Vivo Squatting Exercise in People With Doubtful to Mild Knee Osteoarthritis: A Case-Control Study

Abstract

Background The effects of exercise on osteoarthritic cartilage remain elusive. Objective The objective of this study was to investigate the effect of dynamic in vivo squatting exercise on the magnitude and spatial pattern of acute cartilage responses in people with tibiofemoral osteoarthritis (ie, Kellgren-Lawrence grades 1 and 2). Design This investigation was a case-control study. Methods Eighteen people with radiographic signs of doubtful to mild medial tibiofemoral osteoarthritis were compared with 18 people who were middle-aged and healthy (controls). Three-dimensional magnetic resonance imaging was used to monitor deformation and recovery on the basis of 3-dimensional cartilage volume calculations (ie, total volume and volumes in anterior, central, and posterior subregions) before and after a 30-repetition squatting exercise. Three-dimensional volumes were estimated after semiautomatic segmentation and were calculated at 4 time points (1 before and 3 after scans). Scans obtained after the exercise were separated by 15-minute intervals. Results In both groups, significant deformation was noted in the medial compartment (−3.4% for the femur and −3.2% for the tibia in people with osteoarthritis versus −2.8% for the femur and −3.8% for the tibia in people in the control group). People with osteoarthritis had significant deformation in the lateral femur (−3.9%) and a tendency toward significant deformation in the lateral tibia (−3.1%). From 15 minutes after exercise cessation onward, volume changes were no longer significantly different from the baseline. At all time points, no significant between-group differences were revealed for volume changes. People with osteoarthritis showed a tendency toward slower recovery preceded by larger deformations in entire cartilage plates and subregions. Spatial subregional deformation patterns were similar between groups. Limitations Generalizability is limited to people with doubtful to mild osteoarthritis and low levels of pain. Conclusions Tibiofemoral cartilage deformation appeared similar in magnitude and spatial pattern in people who were middle-aged and either had or did not have tibiofemoral osteoarthritis (ie, Kellgren-Lawrence grades 1 and 2). Restoration of volumes required a 15-minute recovery, especially in the presence of osteoarthritic cartilage degeneration.