High tibiofemoral contact and muscle forces during gait are associated with radiographic knee OA progression over 3 years.

BACKGROUND: The objective of this study was to investigate differences in tibiofemoral joint contact forces between individuals with moderate medial OA who exhibit radiographic knee OA progression within 3 years versus those who do not, and to understand the relationship between model-predicted contact forces and net external moments for this population. METHODS: 27 individuals with moderate medial compartment knee OA underwent baseline instrumented gait analysis. OA progressors were defined as those who experienced at least a one grade increase in medial joint space narrowing at three years. An electromyography-driven musculoskeletal model was used to estimate muscle and tibiofemoral contact forces at baseline, which were compared between progressors and non-progressors using t-tests. RESULTS: Seven individuals experienced radiographic OA progression by 3 years. Progressors walked with significantly higher peaks of medial and total tibiofemoral contact forces, and higher impulse of medial contact forces. Significant and high correlations were found between: first peaks of medial and total contact forces with first peak of the knee adduction moment (R2 = 0.74; R2 = 0.59); second peaks of medial and total knee contact forces with second peaks of knee adduction and flexion moments (R2 = 0.71; R2 = 0.68); medial knee contact force impulse with knee adduction moment impulse (R2 = 0.76). CONCLUSIONS: Higher tibiofemoral joint contact forces during walking were associated with three-year radiographic knee OA progression based on medial joint space narrowing. These results support the need for strategies that reduce compressive knee contact forces through the reduction of adduction and flexion moments during walking.

Concurrent assessment of gait kinematics using marker-based and markerless motion capture.

Kinematic analysis is a useful and widespread tool used in research and clinical biomechanics for the quantification of human movement. Common marker-based optical motion capture systems are time intensive and require highly trained operators to obtain kinematic data. Markerless motion capture systems offer an alternative method for the measurement of kinematic data with several practical benefits. This work compared the kinematics of human gait measured using a deep learning algorithm-based markerless motion capture system to those from a standard marker-based motion capture system. Thirty healthy adult participants walked on a treadmill while data were simultaneously recorded using eight video cameras and seven infrared optical motion capture cameras, providing synchronized markerless and marker-based data for comparison. The average root mean square distance (RMSD) between corresponding joint centers was less than 2.5 cm for all joints except the hip, which was 3.6 cm. Lower limb segment angles relative to the global coordinate system indicated the global segment pose estimates from both systems were very similar, with RMSD of less than 5.5° for all segment angles except those that represent rotations about the long axis of the segment. Lower limb joint angles captured similar patterns for flexion/extension at all joints, ab/adduction at the knee and hip, and toe-in/toe-out at the ankle. These findings indicate that the markerless system would be a suitable alternative technology in cases where the practical benefits of markerless data collection are preferred.

Longitudinal evidence links joint level mechanics and muscle activation patterns to 3-year medial joint space narrowing.

BACKGROUND: It is currently not known if there are different mechanical factors involved in accelerated rates of knee osteoarthritis structural progression. Data regarding the role of the transverse plane moment along with the contributions to joint loading from muscle activity, a primary contributor to the joint loading environment, is not well represented in the current literature on knee OA radiographic progression. The objective of this study was to understand if a 3-year end point corroborates what has been shown for longer term radiographic progression or provides more insight into factors that may be implicated in more accelerated radiographic progression than those shown previously. METHODS: 52 participants visited the Dynamics of Human Motion laboratory at baseline for three-dimensional, self-selected speed over ground walking gait analysis. Differences in magnitude and patterns of 3D knee moments and electromyography waveforms between participants who progressed radiographically from those that did not were compared using t-tests (P < 0.05). FINDINGS: Features of the frontal and transverse plane knee moments along with muscle activation patterns for the lateral gastrocnemius and lateral hamstrings differentiated the progression group from the non-progression group at baseline. INTERPRETATION: In general, the walking gait biomechanics of the progression group in this 3-year radiographic study aligned well with previously reported characteristics of diagnosed or symptomatic osteoarthritis. The higher rotation moment range during stance found with the progression group is a novel finding that points to a need to better understand torsional joint loading and its implications for loading of the knee joint tissues.