Level Walking Conditions Research Articles

PCL insufficient patients with increased translational and rotational passive knee joint laxity have no increased range of anterior–posterior and rotational tibiofemoral motion during level walking

Passive translational tibiofemoral laxity has been extensively examined in posterior cruciate ligament (PCL) insufficient patients and belongs to the standard clinical assessment. However, objective measurements of passive rotational knee laxity, as well as range of tibiofemoral motion during active movements, are both not well understood. None of these are currently quantified in clinical evaluations of patients with PCL insufficiency. The objective of this study was to quantify passive translational and rotational knee laxity as well as range of anterior–posterior and rotational tibiofemoral motion during level walking in a PCL insufficient patient cohort as a basis for any later clinical evaluation and therapy. The laxity of 9 patient knees with isolated PCL insufficiency or additionally posterolateral corner (PLC) insufficiency (8 males, 1 female, age 36.78 ± 7.46 years) were analysed and compared to the contralateral (CL) knees. A rotometer device with a C-arm fluoroscope was used to assess the passive tibiofemoral rotational laxity while stress radiography was used to evaluate passive translational tibiofemoral laxity. Functional gait analysis was used to examine the range of anterior–posterior and rotational tibiofemoral motion during level walking. Passive translational laxity was significantly increased in PCL insufficient knees in comparison to the CL sides (15.5 ± 5.9 mm vs. 3.7 ± 1.9 mm, p < 0.01). Also, passive rotational laxity was significantly higher compared to the CL knees (26.1 ± 8.2° vs. 20.6 ± 5.6° at 90° knee flexion, p < 0.01; 19.0 ± 6.9° vs. 15.5 ± 5.9° at 60° knee flexion, p = 0.04). No significant differences were observed for the rotational (16.3 ± 3.7° vs. 15.2 ± 3.6°, p = 0.43) and translational (17.0 ± 5.4 mm vs. 16.1 ± 2.8 mm, p = 0.55) range of anterior–posterior and rotational tibiofemoral motion during level walking conditions for PCL insufficient knees compared to CL knees respectively. The present study illustrates that patients with PCL insufficiency show a substantial increased passive tibiofemoral laxity, not only in tibiofemoral translation but also in tibiofemoral rotation. Our data indicate that this increased passive multiplanar knee joint laxity can be widely compensated during level walking. Further studies should investigate progressive changes in knee joint laxity and kinematics post PCL injury and reconstruction to judge the individual need for therapy and effects of physiotherapy such as quadriceps force training on gait patterns in PCL insufficient patients.

Effect of joint line preservation on mobile-type bearing unicompartmental knee arthroplasty: finite element analysis.

In this study, we performed a virtual mobile-bearing unicompartmental knee arthroplasty (UKA) on the contact pressure in the tibial insert and articular cartilage by using finite element (FE) analysis to understand clinical observations and elaborate on the potential risks associated with a joint line preservation such as wear on tibial insert and osteoarthritis on other compartment. Neutral position of the knee joint was defined in 0mm joint line, and contact pressure between tibial insert and articular cartilage varies with respect to changes of joint line. Therefore, evaluation of contact pressure may provide the degree of joint line preservation. The FE model for the joint line was developed using a perpendicular projection line from the medial tibial plateau to the anatomical axis. Seven FE models for joint lines in cases corresponding to ± 6, ± 4, ± 2, and 0mm were modeled and analyzed in normal level walking conditions. The maximum contact pressure on the superior and inferior surfaces of the polyethylene insert increased when the joint line became positive while the maximum contact pressure on the articular cartilage increased when the joint line became negative. The increase in the maximum contact pressure in the positive joint line exceeded that in the negative joint line, and this lead to an unsymmetrical maximum contact pressure distribution with respect to the joint line from a 0 reference. The joint line elevation was sensitive to increases or decreases in maximum contact pressures in the mobile-bearing UKA. The findings of the study determined that postoperative joint line preservation is important in mobile-type bearing UKA.

Lower limb biomechanical analysis during an unanticipated step on a bump reveals specific adaptations of walking on uneven terrains.

Although it is clear that walking over different irregular terrain is associated with altered biomechanics, there is little understanding of how we quickly adapt to unexpected variations in terrain. This study aims to investigate which adaptive strategies humans adopt when performing an unanticipated step on an irregular surface, specifically a small bump. Nine healthy male participants walked at their preferred walking speed along a straight walkway during five conditions: four involving unanticipated bumps of two different heights, and one level walking condition. Muscle activation of eight lower limb muscles and three-dimensional gait analysis were evaluated during these testing conditions. Two distinct adaptive strategies were found, which involved no significant change in total lower limb mechanical work or walking speed. An ankle-based strategy was adopted when stepping on a bump with the forefoot, whereas a hip-based strategy was preferred when stepping with the rearfoot. These strategies were driven by a higher activation of the plantarflexor muscles (6-51%), which generated a higher ankle joint moment during the forefoot conditions and by a higher activation of the quadriceps muscles (36-93%), which produced a higher knee joint moment and hip joint power during the rearfoot conditions. These findings provide insights into how humans quickly react to unexpected events and could be used to inform the design of adaptive controllers for wearable robots intended for use in unstructured environments that can provide optimal assistance to the different lower limb joints.

Visual Search Behavior in Individuals With Retinitis Pigmentosa During Level Walking and Obstacle Crossing.

Investigate the visual search strategy of individuals with retinitis pigmentosa (RP) when negotiating a floor-based obstacle compared with level walking, and compared with those with normal vision. Wearing a mobile eye tracker, individuals with RP and normal vision walked along a level walkway or walked along the walkway negotiating a floor-based obstacle. In the level walking condition, tape was placed on the floor to act as an object attracting visual attention. Analysis compared where individuals looked within the environment. In the obstacle compared with level walking condition: (1) the RP group reduced the length of time and the number of times they looked Ahead, and increased the time and how often they looked at features on the ground (Object and Down, P < 0.05); and (2) the visual normal group reduced the time (by 19%) they looked Ahead (P = 0.076), and increased the time and how often they looked at the Object (P < 0.05). Compared with the normal vision group, in both level walking and obstacle conditions, the RP group reduced the time looking Ahead and looked for longer and more often Down (P < 0.05). The RP group demonstrated a more active visual search pattern, looking at more areas on the ground in both level walking and obstacle crossing compared with visual normals. This gaze strategy was invariant across conditions. This is most likely due to the constricted visual field and inability to rely on inferior peripheral vision to acquire information from the floor within the environment when walking.

Assessment of a Smart Sensing Shoe for Gait Phase Detection in Level Walking

Gait analysis and more specifically ambulatory monitoring of temporal and spatial gait parameters may open relevant fields of applications in activity tracking, sports and also in the assessment and treatment of specific diseases. Wearable technology can boost this scenario by spreading the adoption of monitoring systems to a wide set of healthy users or patients. In this context, we assessed a recently developed commercial smart shoe—the FootMoov—for automatic gait phase detection in level walking. FootMoov has built-in force sensors and a triaxial accelerometer and is able to transmit the sensor data to the smartphone through a wireless connection. We developed a dedicated gait phase detection algorithm relying both on force and inertial information. We tested the smart shoe on ten healthy subjects in free level walking conditions and in a laboratory setting in comparison with an optical motion capture system. Results confirmed a reliable detection of the gait phases. The maximum error committed, on the order of 44.7 ms, is comparable with previous studies. Our results confirmed the possibility to exploit consumer wearable devices to extract relevant parameters to improve the subject health or to better manage his/her progressions.

A Comparison of the Degree of Perceived Exertion by Participants In Nordic Walking and Level Walking at Equal Levels of Relative Exercise Intensity

It has been reported that the perceived exertion in level walking (LW) is the same with or lower than that of nordic walking (NW), although the exercise intensity of NW is higher than LW. Based on this fact, it could be expected that absolute intensity, the speed, should differ if the relative intensity, measured using VO 2 level, is the same in both types of walking. This study aimed to clarify the levels of perceived exertion between NW and LW when their VO 2 levels are equivalent. The subjects were eight healthy young males who exercise regularly. They performed three tests: an incremental test to obtain their regression formula between theVO 2max and the speed, the submaximal exercise test of NW (the NW condition) at 40% of each subject's VO 2max speed, and LW test (the LW condition) at the speed we substituted the value of VO 2 provided in the NW condition into the regression formula. They conducted a six-minute exercise in each condition. Measurements included percentage of VO 2 , heart rate reserve (%HRR), and perceived exertion (OMNI scale) of their upper limbs, lower limbs, and whole body. Although there was no significant difference in VO 2 and %HRR, there was in speed, with the subjects walking faster in the LW condition (p<0.01). No significant difference was found between the conditions on the OMNI scale of their whole body and lower limbs, but the NW condition produced significantly higher values than the LW condition for their up- per limbs (p<0.01). The results suggested that the same exercise intensity can be obtained at a slower speed in NW, and higher exertion was perceived only in their arms in NW, with no difference in their lower limbs or whole body.

Simulating activities of daily living with finite element analysis improves fracture prediction for patients with metastatic femoral lesions.

Predicting fracture risk for patients with metastatic femoral lesions remains an important clinical problem. Mirels' criterion remains the most formalized radiographic scoring system with good sensitivity (correctly identifying clinical fractures) but relatively poor specificity (correctly identify cases that do not fracture). A series of patients with metastatic femoral lesions had Computed Tomography (CT) scans, were followed prospectively for 4 months, and categorized into fracture (n = 5), non-fracture (n = 28), or stabilized (n = 11) groups. CT based-Finite Element (FE) modeling was used to predict fracture for these cases using axial compression (AC), level walking (LW), and aggressive stair ascent (ASA) loading conditions. The FE predicted fracture force was greater for the non-fracture compared to the fracture group for all loading cases. The ability of the FE models to predict fracture cases (sensitivity) was similar for the groups (Mirels, AC, LW: 80%, ASA: 100%). The ability of the models to correctly predict the non-fracture cases (specificity) was improved for AC (71%) and LW (86%) loading conditions, when compared to Mirels specificity (43%), but poorer for the ASA (21%) conditions. The results suggest that FE models that assess fracture risk using LW conditions can improve fracture prediction over Mirels scoring in a clinical population.

The influence of incline walking on joint mechanics

Walking is a popular form of exercise and is associated with many health benefits; however, frontal-plane knee joint loading brought about by a large internal knee-abduction moment and cyclic loading could lead to cartilage degeneration over time. Therefore, knee joint mechanics during an alternative walking exercise needs to be analyzed. The purpose of this study was to examine the lower-extremity joint mechanics in the frontal and sagittal planes during incline walking. Fifteen healthy males walked on a treadmill at five gradients (0%, 5%, 10%, 15%, and 20%) at 1.34m/s, and lower-extremity joint mechanics in the frontal and sagittal planes were quantified. The peak internal knee-abduction moment significantly decreased from the level walking condition at all gradients except 5%. Also, a negative relationship between the internal knee-abduction moment and the treadmill gradient was found to exist in 10% increments (0–10%, 5–15%, and 10–20%). The decrease in the internal knee-abduction moment during incline walking could have positive effects on knee joint health such as potentially reducing cartilage degeneration of the knee joint, reducing pain, and decreasing the rate of development of medial tibiofemoral osteoarthritis. This would be beneficial for a knee surgery patient, obese persons, and older adults who are using incline walking for rehabilitation and exercise protocols. Findings from the current study can provide guidance for the development of rehabilitation and exercise prescriptions incorporating incline walking.

A comparison of required coefficient of friction for both feet in level walking

The required coefficient of friction (RCOF) is one of the critical elements in determining whether a slip incident might occur. Most researchers, when measuring RCOF, do not differentiate between the two feet of the same participant under the same walking condition. Results from a recent study ( Chang et al., 2010) indicated that the stochastic distributions of the RCOF of both feet were different in 76% of the cases. Using the previous data ( Chang et al., 2010), this paper presents a comparison of the RCOF for both feet of 50 participants under four level walking conditions resulting from two footwear types and two walking speeds using a t-test, commonly used by safety professionals to compare two pools of data. The current results indicated that 78% of the RCOF data showed a statistically significant difference between the RCOF from two feet for the same participant under each walking condition. The results of the logistic regression analysis used to identify factors that contributed to the outcome of the t-test indicated that the walking speed was the only factor with a statistical significance ( p = 0.044).

3D spinal motion analysis during staircase walking using an ambulatory inertial and magnetic sensing system

Previous research on spinal motion during walking has been restricted to the level walking condition in a gait lab although staircase walking (i.e., stair ascent and descent) exhibits unique biomechanical characteristics. A major difficulty in spinal motion capture during staircase walking is the in-the-lab limitation of measurement techniques. The purpose of this article is twofold: (i) to present an ambulatory spinal motion measurement system based on inertial and magnetic sensors (IMSs) to overcome this limitation and (ii) to demonstrate its application to 3D spinal motion analysis during staircase walking to fill a gap in the spinal kinematics literature. The proposed system is comprised of three tri-axial IMSs on the pelvis/spine measuring 3D angular motions of the pelvis, lumbar spine and thoracic spine and two uni-axial gyroscopes on the shanks providing gait cycle information. The proposed system was employed in comparing the spinal motion during the staircase walking to that of the level walking with respect to the motion pattern, variability, and range of motion (ROM). The test results showed clear differences in spinal motion between the level walking and staircase walking conditions, particularly in regards to the motion pattern and ROM of the flexion/extension and lateral bending of the spine.