Cam and pincer morphologies are potential precursors to hip osteoarthritis and important contributors to non-arthritic hip pain. However, only some hips with these pathomorphologies develop symptoms and joint degeneration, and it is not clear why. Anterior impingement between the femoral head-neck contour and acetabular rim in positions of hip flexion combined with rotation is a proposed pathomechanism in these hips, but this has not been studied in active postures. Our aim was to assess the anterior impingement pathomechanism in both active and passive postures with high hip flexion that are thought to provoke impingement. We recruited nine participants with cam and/or pincer morphologies and with pain, 13 participants with cam and/or pincer morphologies and without pain, and 11 controls from a population-based cohort. We scanned hips in active squatting and passive sitting flexion, adduction, and internal rotation using open MRI and quantified anterior femoroacetabular clearance using the β angle.Aims
Methods
Measures of lower limb alignment and knee joint load during walking were evaluated before and six months after medial opening wedge high tibial osteotomy (HTO) in ninety-five patients with knee medial compartment osteoarthritis (OA). Full-length standing radiographs were used to calculate the mechanical axis angle, and a gait analysis was performed to calculate the external adduction moment about the knee. Results indicated significant decreases in mechanical axis angle and peak adduction moment. These findings provide an indication of the early success of HTO in reducing the extent of lower limb malalignment and knee joint load during walking. Medial opening wedge high tibial osteotomy (HTO) is intended to correct lower limb malalignment, resulting in decreased medial knee joint load and improved function. Due to the potential for the amount of alignment correction to change over time after surgery, frequent follow-up evaluations are encouraged. To evaluate the early changes in lower limb alignment and medial knee joint load experienced during walking after medial opening wedge HTO. Ninety-five patients (seventy-nine males, sixteen females; age range = 21–76 years; BMI range = 18.0–38.5) with knee joint OA affecting primarily the medial compartment underwent radiographic and gait analyses pre-surgically and six months following HTO. Full-length standing radiographs were obtained on both occasions and used to measure the static mechanical axis angle. Three-dimensional kinetic and kinematic data were also collected and combined to calculate the external knee joint adduction moment, an indirect measure of knee joint load. Paired t-tests indicated the mechanical axis angle (mean decrease = 8.32 degrees, 95% CI = 7.54,9.10) and peak external knee joint adduction moment (mean decrease = 1.61%BW*ht, 95% CI = 1.25,1.95) significantly decreased post-operatively (p<
0.001). These results indicate less varus angulation and reduced medial knee joint load following HTO. These preliminary findings suggest that medial opening wedge HTO is an effective surgical treatment for improving alignment and reducing knee joint load. Although these early results are promising, future research is required to determine the long-term success of this surgery in the treatment of knee OA. Funding: CIHR, NSERC, Arthrex Inc.
