Thigh-calf contact parameters for six high knee flexion postures: Onset, maximum angle, total force, contact area, and center of force

Abstract

In high knee flexion, contact between the posterior thigh and calf is expected to decrease forces on tibiofemoral contact surfaces, therefore, thigh-calf contact needs to be thoroughly characterized to model its effect. This study measured knee angles and intersegmental contact parameters in fifty-eight young healthy participants for six common high flexion postures using motion tracking and a pressure sensor attached to the right thigh. Additionally, we introduced and assessed the reliability of a method for reducing noise in pressure sensor output. Five repetitions of two squatting, two kneeling, and two unilateral kneeling movements were completed. Interactions of posture by sex occurred for thigh-calf and heel-gluteal center of force, and thigh-calf contact area. Center of force in thigh-calf regions was farther from the knee joint center in females, compared to males, during unilateral kneeling (82 and 67 mm respectively) with an inverted relationship in the heel-gluteal region (331 and 345 mm respectively), although caution is advised when generalizing these findings from a young, relatively fit sample to a population level. Contact area was larger in females when compared to males (mean of 155.61 and 137.33 cm across postures). A posture main effect was observed in contact force and sex main effects were present in onset and max angle. Males had earlier onset (121.0°) and lower max angle (147.4°) with onset and max angles having a range between movements of 8° and 3° respectively. There was a substantial total force difference of 139 N between the largest and smallest activity means. Force parameters measured in this study suggest that knee joint contact models need to incorporate activity-specific parameters when estimating loading.

Shape is only a weak predictor of deep knee flexion kinematics in healthy and osteoarthritic knees

“…12,13 Deep flexion occurs at the limit of motion, and soft-tissue factors are known to influence deep knee flexion kinematics. 14,15 However, the articular shape is still thought to be important in achieving maximal deep flexion. Indeed, total knee replacement design is predicated on restoring normal shape in order to achieve optimal kinematics.…”

Development of a Full Flexion 3D Musculoskeletal Model of the Knee Considering Intersegmental Contact During High Knee Flexion Movements

“…This disagreement with previous outcomes is a likely result of our intersegmental force and contact area magnitudes being lower than previous reports 15,19 as our sensor was of higher resolution. 1 Tibial contact force estimates including intersegmental contact from this model appear to be more biologically feasible than prior 2D reports. Our peak tibial compression and shear estimates are almost half 4,12 or 1 to 3 BW 12,79,80 lower than sagitttal plane high knee flexion models that did not account for intersegmental contact.…”

“…17 However, their report of thigh-calf contact onset at ∼90°of knee flexion and peak magnitudes of ∼300 N occurring at 120°1 8 contradict prior work. 1,15,19 Similarly, it should be noted that in the work of Wu et al, a 57% reduction in tibiofemoral forces at ∼120°flexion was unexpected as Kingston and Acker, and Zelle et al reported <20 N of thigh-calf contact force at this angle (∼120°) and peak flexion angles of ∼150°i n a similar movement.…”

“…Normal force 3D orientation, center of force, magnitude, and active area of intersegmental contact were input as a function of knee flexion angle. 1 The 8-bit pressure sensor has a spatial resolution of 3.9 sensels/cm 2 and a sensing region that was 15.75 cm wide by 39.62 cm long. It was conditioned to 103.4 kPa 10 times in 3-second cycles, equilibrated for 30 seconds at 3 points (34.5, 68.9, and 103.4 kPa), then calibrated following the manufacturer's nonlinear (power) procedure.…”

Prediction of thigh-calf contact parameters from anthropometric regression

“…1,2 Thigh-calf forces 3 were applied to a two-dimensional rigid body model and to a finite element model of the tibia, patella, and quadriceps tendon resulting in a compressive force of 3.07 BW versus 4.37 BW when thigh-calf contact was included. 1 Based on our measurements of thigh-calf contact forces and center of force (CoF) in full flexion, 4 on average, peak external extension moments of ≈0.25 Nm/kg about the knee joint result from intersegmental contact. These moments would presumably reduce quadriceps force, a main contributor to both the extension moment and compressive force at the knee joint.…”