Previous studies evaluating the effectiveness of OA offloading knee braces focused on qualitative results. The objective of this study was to analyze the effectiveness of an off-loading knee brace with respect to in vivo three-dimensional knee kinematics to quantitatively measure the changes in medial joint space and relative bone alignment when wearing the brace.
Twenty subjects diagnosed with medial compartmental joint space narrowing and varus deformity due to OA were recruited. During fluoroscopic surveillance, subjects performed normal gait on a treadmill with and without the brace. Images were sequenced at heel-strike and mid-stance during the weight-bearing portion of gait. 3D-to-2D image registration was performed on each subject using 3D bone models derived from CT segmentation and 3D ultrasound scans.
Medial joint space was to increase when the brace was applied in all subjects (1.6 ± 0.7 mm at heel-strike, 1.6 ± 0.8 mm at mid-stance) and was statistically significant (P < .001). It was also found that sixteen of the twenty subjects experienced a medial joint space increase of more than 1.0 mm during heel-strike while thirteen of twenty experienced this change at mid-stance. While wearing the brace, over half of the subjects experienced a valgus correction to their alignment.
All subjects in this study experienced a positive change in the medial joint space when wearing the offloading knee brace. In addition, many subjects also saw joint space values representative of previously documented, nonosteoarthritic subjects and valgus changes in bone alignment more akin to the normal knee.