How tibiofemoral alignment and contact locations affect predictions of medial and lateral tibiofemoral contact forces

Abstract

Understanding degeneration of biological and prosthetic knee joints requires knowledge of the in-vivo loading environment during activities of daily living. Musculoskeletal models can estimate medial/lateral tibiofemoral compartment contact forces, yet anthropometric differences between individuals make accurate predictions challenging. We developed a full-body OpenSim musculoskeletal model with a knee joint that incorporates subject-specific tibiofemoral alignment (i.e. knee varus-valgus) and geometry (i.e. contact locations). We tested the accuracy of our model and determined the importance of these subject-specific parameters by comparing estimated to measured medial and lateral contact forces during walking in an individual with an instrumented knee replacement and post-operative genu valgum (6°). The errors in the predictions of the first peak medial and lateral contact force were 12.4% and 11.9%, respectively, for a model with subject-specific tibiofemoral alignment and contact locations determined via radiographic analysis, vs. 63.1% and 42.0%, respectively, for a model with generic parameters. We found that each degree of tibiofemoral alignment deviation altered the first peak medial compartment contact force by 51N (r2=0.99), while each millimeter of medial-lateral translation of the compartment contact point locations altered the first peak medial compartment contact force by 41N (r2=0.99). The model, available at www.simtk.org/home/med-lat-knee/, enables the specification of subject-specific joint alignment and compartment contact locations to more accurately estimate medial and lateral tibiofemoral contact forces in individuals with non-neutral alignment.

The Influence of Component Alignment and Ligament Properties on Tibiofemoral Contact Forces in Total Knee Replacement

“…In agreement with previous modeling studies [23,68,69], the coronal alignment of the femoral and tibial components affected the predicted knee contact loading patterns. While total contact force magnitudes were insensitive to alignment (Fig.…”

Biofeedback for Gait Retraining Based on Real-Time Estimation of Tibiofemoral Joint Contact Forces

“…Offline estimation of MTFF using CEINMS was previously validated in [48] using data from instrumented knee implants [41]. Despite the differences between instrumented knee implants and healthy knees, CEINMS accounts for personalized excitation patterns and the OpenSim anatomical model can be adjusted to include variations in knee geometry and alignment [44, 48]. Thus, we considered CEINMS estimations of internal forces to be valid also on healthy subjects, and the offline CEINMS estimates of MTFF were used as the criteria for real-time verification in this study (Table I, Fig.…”

“…OpenSim [43] is a popular musculoskeletal modelling software for the analysis of the human motion that can account for individual variations in anatomy and movement [44]. However, OpenSim estimates muscle forces via optimisation-based algorithms (e.g.…”

Tibiofemoral contact forces during walking, running and sidestepping

“…First, the estimation of the tibiofemoral contact forces was sensitive to the musculoskeletal [16] and knee contact geometries [39]. We linearly scaled a generic anatomic model to match each participant's dimensions, but linear 12 scaling is a crude method to personalize musculoskeletal anatomy.…”

“…The tibiofemoral contact forces are sensitive to the alignment of the lower-limb [39], thus, locking the knee adduction/adduction rotations for those participants with non-neutral alignment would result in inaccurate model predictions of knee contact forces. However, we did not have standing lower-limb radiographs, therefore, we cannot comment on the lower-limb alignment of the participants, but note that it is a limitation of this study.…”