scholarly journals Human standing: does the control strategy preprogram a rigid knee?

2013 ◽  
Vol 114 (12) ◽  
pp. 1717-1729 ◽  
Author(s):  
Irene Di Giulio ◽  
Vasilios Baltzopoulos ◽  
Constantinos N. Maganaris ◽  
Ian D. Loram
Keyword(s):  
Internal Rotation ◽  
Skill Acquisition ◽  
Knee Flexion ◽  
Degrees Of Freedom ◽  
Control Strategies ◽  
Response Patterns ◽  
Ankle Stiffness ◽  
Perturbation Force ◽  
Energy Absorbing ◽  
Hip Internal Rotation

Human standing requires control of multisegmental configuration. Does the postural system normally allow flexible adjustment of configuration, or does it minimize degrees of freedom at the ankle, knee, and hip joints? Gentle, external, unpredictable, sagittal, mechanical perturbations (randomized force, 1–10 N; duration, 0.2–2 s; and leg) were applied to either knee of 24 healthy participants who stood symmetrically for 200 s. The translation of knee perturbation force to ankle, knee, and hip joint rotations in the perturbed and unperturbed legs was studied. We assessed whether consequent joint rotations indicated a stiff configuration-conserving or viscous energy-absorbing relationship to the knee perturbation. Two distinctive response patterns were observed. Twenty-two participants showed limited knee flexion and high ankle stiffness, whereas two participants showed substantial knee flexion, low ankle stiffness, measurable internal rotation of the unperturbed hip (0.4 ± 0.3 vs. 3.0 ± 1°, 5.7 ± 17 vs. 0.5 ± 0.3 N/°, 1.1 ± 0.4°, respectively; mean ± SD), and a viscous relationship between perturbation force and subsequent ankle flexion, knee flexion, and perturbed and unperturbed hip internal rotation. The size of knee-flexion response to knee perturbations was uncorrelated with the extent of unperturbed standing sway. Normal standing conceals a large interindividual range in leg control strategies, indicating adaptive potential to progress with development and skill acquisition and decline with age, disease, injury, and fear. Commonly, leg configuration was maintained stiffly. Less commonly, a bilateral, low-stiffness, energy-absorbing strategy utilizing the available degrees of freedom was shown. We propose that identification of individual coordination strategy has diagnostic and prognostic potential in relation to perceptual-posture-movement-fall interactions.

scholarly journals EFFECT OF STATIC ANATOMIC ALIGNMENT ON DYNAMIC LIMB VALGUS DURING SIDE-STEP CUTTING IN UNINJURED ADOLESCENT ATHLETES

2019 ◽  
Vol 7 (3_suppl) ◽  
pp. 2325967119S0002
Author(s):  
Nicole Mueske ◽  
Daniel T. Feifer ◽  
Curtis VandenBerg ◽  
J. Lee Pace ◽  
Mia J. Katzel ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Internal Rotation ◽  
Knee Flexion ◽  
External Rotation ◽  
Acl Injury ◽  
Adolescent Athletes ◽  
Knee Abduction ◽  
Hip Flexion ◽  
Hip Internal Rotation ◽  
Hip Rotation

BACKGROUND Dynamic limb valgus, combining hip adduction and internal rotation with knee abduction posture and moments, has been implicated in ACL injury. However, the contribution of static lower extremity alignment to dynamic limb valgus is unknown. This study assessed the relationships among lower extremity static alignment and dynamic kinematics and kinetics during side-step cutting in uninjured adolescent athletes. METHODS This prospective study included 88 limbs from 44 uninjured athletes aged 8-15 years (mean 12.3, SD 2.3; 19 (44%) female) who were evaluated during an anticipated 45° side-step cut. 3D lower extremity kinematics and kinetics from a custom 6 degree of freedom model were assessed while standing and during the loading phase of the cut from initial contact to peak knee flexion; 2-3 trials per limb were averaged for analysis. Femoral anteversion was measured for each limb with the participant lying prone. Relationships among static and dynamic measures were investigated using correlation and multiple linear regression. RESULTS In terms of static alignment, more static hip internal rotation and more static knee external rotation (tibia external relative to femur) were associated with more internal hip rotation and external knee rotation dynamically during cutting (r=0.34, p=0.001) (Table 1). Static hip adduction was also related to more external hip rotation and less hip flexion dynamically (p=0.24, p=0.02). More static knee abduction, external hip rotation and hip adduction were associated with higher average knee abduction angles during cutting (r=0.25, p=0.02). However, only static external knee rotation was associated with higher dynamic knee abduction moments (r=0.48, p<0.0001) (Figure 1). During cutting, positive associations were observed between hip flexion, knee flexion, and hip internal rotation (r=0.24, p=0.03). Knee adduction angles were related to more hip flexion, internal hip rotation, and knee external rotation (r=0.25, p=0.02). Additionally, lower peak knee flexion was associated with higher peak ground reaction force and more external knee rotation (r=0.24, p=0.02). Both simple correlation and multiple regression analysis indicated that higher knee abduction moments were related dynamically to higher knee abduction angles, greater knee external rotation, higher hip abduction angles, and greater hip internal rotation (R2=0.72, p<0.001). After considering dynamic metrics, no static measure remained significantly related to knee abduction moments. CONCLUSION/SIGNIFICANCE Static knee rotation was the only anatomic alignment measure associated with knee abduction moments during side-step cutting in uninjured adolescent athletes. Knee abduction moments were influenced more by dynamic posture than static alignment. As knee abduction moments have been implicated in ACL injury, this study supports the notion of dynamic limb valgus, specifically increased knee abduction and hip internal rotation, relating to ACL injury. Motion analysis can be used to identify these risky biomechanical patterns, and neuromuscular training can be used to correct them. Since knee abduction moments are primarily determined by dynamic posture, neuromuscular training can be used to reduce these moments and ACL injury risk. [Figure: see text][Table: see text]

scholarly journals Influence of the Anterolateral Ligament on Knee Laxity: A Biomechanical Cadaveric Study Measuring Knee Kinematics in 6 Degrees of Freedom Using Dynamic Radiostereometric Analysis

2018 ◽  
Vol 6 (8) ◽  
pp. 232596711878969 ◽  
Author(s):  
Emil Toft Nielsen ◽  
Kasper Stentz-Olesen ◽  
Sepp de Raedt ◽  
Peter Bo Jørgensen ◽  
Ole Gade Sørensen ◽  
...  
Keyword(s):  
Internal Rotation ◽  
Acl Reconstruction ◽  
Knee Flexion ◽  
Degrees Of Freedom ◽  
Knee Kinematics ◽  
Knee Laxity ◽  
Anterolateral Ligament ◽  
Single Bundle ◽  
Anterior Translation ◽  
6 Degrees Of Freedom

Background: An anterior cruciate ligament (ACL) rupture often occurs during rotational trauma to the knee and may be associated with damage to extracapsular knee rotation–stabilizing structures such as the anterolateral ligament (ALL). Purpose: To investigate ex vivo knee laxity in 6 degrees of freedom with and without ALL reconstruction as a supplement to ACL reconstruction. Study Design: Controlled laboratory study. Methods: Cadaveric knees (N = 8) were analyzed using dynamic radiostereometry during a controlled pivotlike dynamic movement simulated by motorized knee flexion (0° to 60°) with 4-N·m internal rotation torque. We tested the cadaveric specimens in 5 successive ligament situations: intact, ACL lesion, ACL + ALL lesion, ACL reconstruction, and ACL + ALL reconstruction. Anatomic single-bundle reconstruction methods were used for both the ACL and the ALL, with a bone-tendon quadriceps autograft and gracilis tendon autograft, respectively. Three-dimensional kinematics and articular surface interactions were used to determine knee laxity. Results: For the entire knee flexion motion, an ACL + ALL lesion increased the mean knee laxity ( P < .005) for internal rotation (2.54°), anterior translation (1.68 mm), and varus rotation (0.53°). Augmented ALL reconstruction reduced knee laxity for anterior translation ( P = .003) and varus rotation ( P = .047) compared with ACL + ALL–deficient knees. Knees with ACL + ALL lesions had more internal rotation ( P < .001) and anterior translation ( P < .045) at knee flexion angles below 40° and 30°, respectively, compared with healthy knees. Combined ACL + ALL reconstruction did not completely restore native kinematics/laxity at flexion angles below 10° for anterior translation and below 20° for internal rotation ( P < .035). ACL + ALL reconstruction was not found to overconstrain the knee joint. Conclusion: Augmented ALL reconstruction with ACL reconstruction in a cadaveric setting reduces internal rotation, varus rotation, and anterior translation knee laxity similar to knee kinematics with intact ligaments, except at knee flexion angles between 0° and 20°. Clinical Relevance: Patients with ACL injuries can potentially achieve better results with augmented ALL reconstruction along with ACL reconstruction than with stand-alone ACL reconstruction. Furthermore, dynamic radiostereometry provides the opportunity to examine clinical patients and compare the recontructed knee with the contralateral knee in 6 degrees of freedom.

Biomechanical Analysis of an Isolated Fibular (Lateral) Collateral Ligament Reconstruction Using an Autogenous Semitendinosus Graft

2007 ◽  
Vol 35 (9) ◽  
pp. 1521-1527 ◽  
Author(s):  
Benjamin R. Coobs ◽  
Robert F. LaPrade ◽  
Chad J. Griffith ◽  
Bradley J. Nelson
Keyword(s):  
Internal Rotation ◽  
Knee Flexion ◽  
Ligament Reconstruction ◽  
External Rotation ◽  
Anatomic Reconstruction ◽  
Ligament Injury ◽  
Collateral Ligament ◽  
Fibular Collateral Ligament ◽  
Normal Stability ◽  
Semitendinosus Graft

Background The fibular collateral ligament is the primary stabilizer to varus instability of the knee. Untreated fibular collateral ligament injuries can lead to residual knee instability and can increase the risk of concurrent cruciate ligament reconstruction graft failures. Anatomic reconstructions of the fibular collateral ligament have not been biomechanically validated. Purpose To describe an anatomic fibular collateral ligament reconstruction using an autogenous semitendinosus graft and to test the hypothesis that using this reconstruction technique to treat an isolated fibular collateral ligament injury will restore the knee to near normal stability. Study Design Controlled laboratory study. Methods Ten nonpaired, fresh-frozen cadaveric knees were biomechanically subjected to a 10 N·m varus moment and 5 N·m external and internal rotation torques at 0°, 15°, 30°, 60°, and 90° of knee flexion. Testing was performed with an intact and sectioned fibular collateral ligament, and also after an anatomic reconstruction of the fibular collateral ligament with an autogenous semitendinosus graft. Motion changes were assessed with a 6 degree of freedom electromagnetic motion analysis system. Results After sectioning, we found significant increases in varus rotation at 0°, 15°, 30°, 60°, and 90°, external rotation at 60° and 90°, and internal rotation at 0°, 15°, 30°, 60°, and 90° of knee flexion. After reconstruction, there were significant decreases in motion in varus rotation at 0°, 15°, 30°, 60°, and 90°, external rotation at 60° and 90°, and internal rotation at 0°, 15°, and 30° of knee flexion. In addition, we observed a full recovery of knee stability in varus rotation at 0°, 60°, and 90°, external rotation at 60° and 90°, and internal rotation at 0° and 30° of knee flexion. Conclusion An anatomic fibular collateral ligament reconstruction restores varus, external, and internal rotation to near normal stability in a knee with an isolated fibular collateral ligament injury. Clinical Significance An anatomic reconstruction of the fibular collateral ligament with an autogenous semitendinosus graft is a viable option to treat nonrepairable acute or chronic fibular collateral ligament tears in patients with varus instability.

scholarly journals Control Strategies for Gait Tele-Rehabilitation System Based on Parallel Robotics

2021 ◽  
Vol 11 (23) ◽  
pp. 11095
Author(s):  
Antonio P. L. Bo ◽  
Leslie Casas ◽  
Gonzalo Cucho-Padin ◽  
Mitsuhiro Hayashibe ◽  
Dante Elias
Keyword(s):  
Degrees Of Freedom ◽  
Control Strategies ◽  
Subjective Evaluation ◽  
Wearable Sensors ◽  
Movement Data ◽  
Trunk Inclination ◽  
Limited Degree ◽  
Parallel Robotics ◽  
Limb Rehabilitation ◽  
Technical Capacity

Among end-effector robots for lower limb rehabilitation, systems based on Stewart–Gough platforms enable independent movement of each foot in six degrees of freedom. Nevertheless, control strategies described in recent literature have not been able to fully explore the potential of such a mechatronic system. In this work, we propose two novel approaches for controlling a gait simulator based on Stewart–Gough platforms. The first strategy provides the therapist direct control of each platform using movement data measured by wearable sensors. The following scheme is designed to improve the level of engagement of the patient by enabling a limited degree of control based on trunk inclination. Both strategies are designed to facilitate future studies in tele-rehabilitation settings. Experimental results have illustrated the feasibility of both control interfaces, either in terms of system performance or user subjective evaluation. Technical capacity to deploy in tele-rehabilitation was also verified in this work.

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