Musculoskeletal loading in the symptomatic and asymptomatic knees of middle‐aged osteoarthritis patients

Abstract

This study quantified the contributions by muscles, gravity, and inertia to the tibiofemoral compartment forces in the symptomatic (SYM) and asymptomatic (ASYM) limbs of varus mal-aligned medial knee osteoarthritis (OA) patients, and compared the results with healthy controls (CON). Muscle forces and tibiofemoral compartment loads were calculated using gait data from 39 OA patients and 15 controls aged 49 ± 7 years. Patients exhibited lower knee flexion angle, higher hip abduction, and knee adduction angles, lower internal knee flexion torque but higher external knee adduction moment. Muscle forces were highest in CON except hamstrings, which was highest in SYM. ASYM muscle forces were lowest for biceps femoris short head and gastrocnemius but otherwise intermediate between SYM and CON. In all subjects, vasti, hamstrings, gastrocnemius, soleus, gluteus medius, gluteus maximus, and gravity were the largest contributors to medial compartment force (MCF). Inertial contributions were negligible. Highest MCF was found in SYM throughout stance. Small increases in contributions from hamstrings, gluteus maximus, gastrocnemius, and gravity at the first peak; soleus and rectus femoris at the second peak; and soleus, gluteus maximus, gluteus medius, and gravity during mid-stance summed to produce significantly higher total MCF. Compared to CON, the ASYM limb exhibited similar peak MCF but higher mid-stance MCF. In patients, diminished non-knee-spanning muscle forces did not produce correspondingly diminished MCF contributions due to the influence of mal-alignment. Our findings emphasize consideration of muscle function, lower-limb alignment, and mid-stance loads in developing interventions for OA, and inclusion of the asymptomatic limb in clinical assessments. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:321-330, 2017.

Evidence and mechanism by which upper partial fibulectomy improves knee biomechanics and decreases knee pain of osteoarthritis

“…Although we do not know the precise mechanism by which upper partial fibulectomy improved HKA angle and reduced the overall peak KAM, we hypothesized that increased muscle activity of biceps femoris may be responsible. Compared with healthy controls, preoperative assessments showed that the KOA patients had significant lower muscle activity of biceps femoris for the affected (operated) side, which was in agreement with Sritharan et al Interestingly, the muscle activity increased immediately and was equivalent to controls by 6 months after surgery. Furthermore, we noted that after surgery the proximal fibula head was displaced superiorly in 10 cases and inferiorly in 19 cases.…”

Lower‐limb muscle function during gait in varus mal‐aligned osteoarthritis patients

“…Thus a similar, albeit much more subtle, compensatory mechanism may occur in our OA patient cohort to facilitate functional improvements during gait, enabling them to walk at speeds comparable to controls despite advanced disease and symptoms of OA. In fact soleus and gastrocnemius muscle forces were lower in patients (Supplementary Table S2 and Sritharan et al) suggesting that kinematic adaptations in OA gait, currently understood to mitigate pain and improve knee‐joint stability, may also confer small but important advantages for lower‐limb muscle function. Further longitudinal research would help to determine if such functional adaptations do indeed develop with OA progression, and continue to change as these patients age and become less mobile.…”

“…Previously reported gait data for 39 medial knee OA patients and 15 healthy controls were used for this study (Table ). All gait experiments were performed at the Wolf Orthopaedic Biomechanics Laboratory, Fowler Kennedy Sport Medicine Clinic, University of Western Ontario.…”

“…A modeling pipeline for calculating joint angles, joint torques and muscle forces was implemented using Matlab (The Mathworks Inc., Natick, MA) and OpenSim, an open‐source musculoskeletal modeling package. For each subject, a scaled‐generic whole‐body three‐dimensional musculoskeletal model was created, with segmental inertial properties, muscle‐tendon attachment sites, and muscle‐tendon paths scaled based on segmental dimensions calculated from each subject's static trial.…”

“…The internal knee adduction and internal–external rotation torques were not included in the static optimization analysis. Time histories of joint angles and muscle forces calculated for these participant groups using the aforementioned procedures were previously reported, with peak values provided in the present study as Supplementary Material (Tables S1 and S2, respectively).…”