Tibiofemoral kinematics and condylar motion during the stance phase of gait

Accurate knowledge of the dynamic knee motion in-vivo is instrumental for understanding normal and pathological function of the knee joint. However, interpreting motion of the knee joint during gait in other than the sagittal plane remains controversial. In this study, we utilized the dual fluoroscopic imaging technique to investigate the six-degree-of-freedom kinematics and condylar motion of the knee during the stance phase of treadmill gait in eight healthy volunteers at a speed of 0.67 m/s. We hypothesized that the 6DOF knee kinematics measured during gait will be different from those reported for non-weightbearing activities, especially with regards to the phenomenon of femoral rollback. In addition, we hypothesized that motion of the medial femoral condyle in the transverse plane is greater than that of the lateral femoral condyle during the stance phase of treadmill gait. The rotational motion and the anterior–posterior translation of the femur with respect to the tibia showed a clear relationship with the flexion–extension path of the knee during the stance phase. Additionally, we observed that the phenomenon of femoral rollback was reversed, with the femur noted to move posteriorly with extension and anteriorly with flexion. Furthermore, we noted that motion of the medial femoral condyle in the transverse plane was greater than that of the lateral femoral condyle during the stance phase of gait (17.4±2.0 mm vs. 7.4±6.1 mm, respectively; p<0.01). The trend was opposite to what has been observed during non-weightbearing flexion or single-leg lunge in previous studies. These data provide baseline knowledge for the understanding of normal physiology and for the analysis of pathological function of the knee joint during walking. These findings further demonstrate that knee kinematics is activity-dependent and motion patterns of one activity (non-weightbearing flexion or lunge) cannot be generalized to interpret a different one (gait).     

Muscular contributions to hip and knee extension during the single limb stance phase of normal gait: a framework for investigating the causes of crouch gait

Crouch gait, a troublesome movement abnormality among persons with cerebral palsy, is characterized by excessive flexion of the hips and knees during stance. Treatment of crouch gait is challenging, at present, because the factors that contribute to hip and knee extension during normal gait are not well understood, and because the potential of individual muscles to produce flexion or extension of the joints during stance is unknown. This study analyzed a three-dimensional, muscle-actuated dynamic simulation of walking to quantify the angular accelerations of the hip and knee induced by muscles during normal gait, and to rank the potential of the muscles to alter motions of these joints. Examination of the muscle actions during single limb stance showed that the gluteus maximus, vasti, and soleus make substantial contributions to hip and knee extension during normal gait. Per unit force, the gluteus maximus had greater potential than the vasti to accelerate the knee toward extension. These data suggest that weak hip extensors, knee extensors, or ankle plantar flexors may contribute to crouch gait, and strengthening these muscles--particularly gluteus maximus--may improve hip and knee extension. Abnormal forces generated by the iliopsoas or adductors may also contribute to crouch gait, as our analysis showed that these muscles have the potential to accelerate the hip and knee toward flexion. This work emphasizes the need to consider how muscular forces contribute to multijoint movements when attempting to identify the causes of abnormal gait.     

A finite element model of the lower limb during stance phase of gait cycle including the muscle forces

Background

Results of finite element (FE) analyses can give insight into musculoskeletal diseases if physiological boundary conditions, which include the muscle forces during specific activities of daily life, are considered in the FE modelling. So far, many simplifications of the boundary conditions are currently made. This study presents an approach for FE modelling of the lower limb for which muscle forces were included.

Methods

The stance phase of normal gait was simulated. Muscle forces were calculated using a musculoskeletal rigid body (RB) model of the human body, and were subsequently applied to a FE model of the lower limb. It was shown that the inertial forces are negligible during the stance phase of normal gait. The contact surfaces between the parts within the knee were modelled as bonded. Weak springs were attached to the distal tibia for numerical reasons.

Results

Hip joint reaction forces from the RB model and those from the FE model were similar in magnitude with relative differences less than 16%. The forces of the weak spring were negligible compared to the applied muscle forces. The maximal strain was 0.23% in the proximal region of the femoral diaphysis and 1.7% in the contact zone between the tibia and the fibula.

Conclusions

The presented approach based on FE modelling by including muscle forces from inverse dynamic analysis of musculoskeletal RB model can be used to perform analyses of the lower limb with very realistic boundary conditions. In the present form, this model can be used to better understand the loading, stresses and strains of bones in the knee area and hence to analyse osteotomy fixation devices.

     

In vivo biomechanical behavior of the human heel pad during the stance phase of gait

A technique is introduced for simultaneous measurements of the heel pad tissue deformation and the heel–ground contact stresses developing during the stance phase of gait. Subjects walked upon a gait platform integrating the contact pressure display optical method for plantar pressure measurements and a digital radiographic fluoroscopy system for skeletal and soft tissue motion recording. Clear images of the posterior-plantar aspect of the calcaneus and enveloping soft tissues were obtained simultaneously with the pressure distribution under the heel region throughout the stance phase of gait. The heel pad was shown to undergo a rapid compression during initial contact and heel strike, reaching a strain of 0.39±0.05 in about 150 ms. The stress–strain relation of the heel pad was shown to be highly non-linear, with a compression modulus of 105±11 kPa initially and 306±16 kPa at 30% strain. The energy dissipation during heel strike was evaluated to be 17.8±0.8%. The present technique is useful for biomechanical as well as clinical evaluation of the stress–strain and energy absorption characteristics of the heel pad in vivo, during natural gait.     

Biomechanics of the double rocker sole shoe: gait kinematics and kinetics

The use of footwear with contoured soles is common in treatment and care of patients with diabetes; these rocker sole shoes are designed to alleviate loading in key areas on the plantar surface of the foot, reducing pressure in key areas and alleviating pain, and potential soft tissue damage. While investigations of pressure changes have been conducted, no quantitative study to date has addressed the three-dimensional (3D) kinematic and kinetic changes that result from using these shoes. Forty subjects were tested wearing both unmodified and double rocker sole shoes, and the resulting motion patterns were compared to assess change caused by the rocker sole. Overall walking speed remained unchanged throughout testing; slightly increased flexion (<5 degrees ) was apparent at the hip, knee, and ankle during early and mid-stance. These results demonstrate the maintenance of gait function with minimal kinematic changes when using the rocker sole shoe. Investigations of multisegmental foot motion may reveal additional information about the contour effects; analysis of contour variations may also be warranted to investigate the possibility of controlling motion based on rocker sole parameters.     

Effects of ramp negotiation, paving type and shoe sole geometry on toe clearance in young adults

Trips are a major cause of falls and result from involuntary contact of the foot with the ground during the swing phase of gait. Adequate toe clearance during swing is therefore crucial for safe locomotion. To date, little is known about the effects of environmental factors and footwear on toe clearance. This study reports on modulation of toe clearance and toe clearance variability in response to changes in ground inclination, paving type, and shoe sole geometry. Toe clearance and toe clearance variability for ten healthy young adults were calculated two-fold: a) for the commonly-used position on the foremost part of the sole of the shoe and b) for the lowest of a total of 7 sole positions, located between the metatarsals and the toe tip across the entire width of the sole. Utilizing a full-factorial design we found that toe clearance was affected by ground inclination, paving type, and sole geometry regardless of the computational method used (with p-values<0.01) but the use of the foremost part of the sole for toe clearance calculation results is an overestimation of this value. Our findings highlight the importance of considering footwear and environmental factors when assessing the risk of tripping. Future work needs to investigate to which extent the same factors affect toe clearance in more vulnerable parts of the population.     

Intra and intersession reliability of balance measures during one-leg standing in young adults

A study was designed to investigate the intra and intersession reliability during 1-leg standing recorded from a computerized balance platform. Thirty-nine healthy young men (n = 17, age range: 20-30 years) and women (n = 22, age range: 21-28 years) performed 3 testing sessions, with the second session 30 minutes (intrasession comparison) and the third session 1 week (intersession comparison) after the initial testing session. Within each testing session, participants completed 3 trials of 1-leg standing with their dominant leg. Reliability statistics were calculated using the mean of all 3 trials during each session for 6 balance measures (i.e., total displacements of the center of pressure [CoP], the CoP displacements in mediolateral and anterior-posterior directions, and the CoP speed and CoP area and their SD). Test-retest reliability was examined calculating both, intraclass correlation coefficient (ICC) with 95% confidence interval (95% CI) and Bland-Altman plots. In both sexes and irrespective of balance measure, ICC values were ≥0.75 except for 1 parameter in men. This indicates an excellent intra and intersession reliability. Bland-Altman plots confirmed these findings by showing that only 1 or 2 (4.5-11.8%) of the data points were beyond the 95% CI. Practitioners and clinicians are provided with a posturographic test setup that proved to be reliable. Researchers can use these data to identify the range in which the true value of a subject's score lies and estimate a priori sample sizes.     

The influence and biomechanical role of cartilage split line pattern on tibiofemoral cartilage stress distribution during the stance phase of gait

This study presents an evaluation of the role that cartilage fibre ‘split line’ orientation plays in informing femoral cartilage stress patterns. A two-stage model is presented consisting of a whole knee joint coupled to a tissue-level cartilage model for computational efficiency. The whole joint model may be easily customised to any MRI or CT geometry using free-form deformation. Three ‘split line’ patterns (medial–lateral, anterior–posterior and random) were implemented in a finite element model with constitutive properties referring to this ‘split line’ orientation as a finite element fibre field. The medial–lateral orientation was similar to anatomy and was derived from imaging studies. Model predictions showed that ‘split lines’ are formed along the line of maximum principal strains and may have a biomechanical role of protecting the cartilage by limiting the cartilage deformation to the area of higher cartilage thickness.     

A longitudinal study of impact and early stance loads during gait following arthroscopic partial meniscectomy

People following arthroscopic partial medial meniscectomy (APM) are at increased risk of developing knee osteoarthritis. High impact loading and peak loading early in the stance phase of gait may play a role in the pathogenesis of knee osteoarthritis. This was a secondary analysis of longitudinal data to investigate loading-related indices at baseline in an APM group (3 months post-surgery) and a healthy control group, and again 2 years later (follow-up). At baseline, 82 participants with medial APM and 38 healthy controls were assessed, with 66 and 23 re-assessed at follow-up, respectively. Outcome measures included: (i) heel strike transient (HST) presence and magnitude, (ii) maximum loading rate, (iii) peak vertical force (F_z) during early stance. At baseline, maximum loading rate was lower in the operated leg (APM) and non-operated leg (non-APM leg) compared to controls (p≤0.03) and peak F_z was lower in the APM leg compared to non-APM leg (p≤0.01). Over 2 years, peak F_z increased in the APM leg compared to the non-APM leg and controls (p≤0.01). Following recent APM, people may adapt their gait to protect the operated knee from excessive loads, as evidenced by a lower maximum loading rate in the APM leg compared to controls, and a reduced peak F_z in the APM leg compared to the non-APM leg. No differences at follow-up may suggest an eventual return to more typical gait. However, the increase in peak F_z in the APM leg may be of concern for long-term joint health given the compromised function of the meniscus.     

A dynamic optimization technique for predicting muscle forces in the swing phase of gait

The muscle force sharing problem was solved for the swing phase of gait using a dynamic optimization algorithm. For comparison purposes the problem was also solved using a typical static optimization algorithm. The objective function for the dynamic optimization algorithm was a combination of the tracking error and the metabolic energy consumption. The latter quantity was taken to be the sum of the total work done by the muscles and the enthalpy change during the contraction. The objective function for the static optimization problem was the sum of the cubes of the muscle stresses. To solve the problem using the static approach, the inverse dynamics problem was first solved in order to determine the resultant joint torques required to generate the given hip, knee and ankle trajectories. To this effect the angular velocities and accelerations were obtained by numerical differentiation using a low-pass digital filter. The dynamic optimization problem was solved using the Fletcher-Reeves conjugate gradient algorithm, and the static optimization problem was solved using the Gradient-restoration algorithm. The results show influence of internal muscle dynamics on muscle control histories vis a vis muscle forces. They also illustrate the strong sensitivity of the results to the differentiation procedure used in the static optimization approach.     

Internal consistency and short-term test-retest reliability of the University of Pennsylvania Smell Identification Test

Measures of internal consistency and short-term test-retestreliability of the University of Pennsylvania Smell IdentificationTest (UPSIT) were determined in 69 people who showed a broadrange of test scores at an earlier test administration. In addition,two procedures for releasing the microencapsulated odorantswere compared. The split-half reliability coefficients for thetwo administrations were r = 0.930 and r = 0.957, respectively(p <0.001). The test-retest (– 2-week interval) coefficientwas r = 0.949 (p <0.001). Release of the odorants by thetip of a #2 lead pencil resulted in scores equivalent to thoseobtained by releasing them with #120 sandpaper. These data,along with those collected previously on the long-term test-retestreliability (r = 0.918), indicate that the UPSIT is a highlyreliable and internally consistent test of smell function.     

Biomechanical analysis of the stance phase during barefoot and shod running

This study investigated spatio-temporal variables, ground reaction forces and sagittal and frontal plane kinematics during the stance phase of nine trained subjects running barefoot and shod at three different velocities (3.5, 4.5, 5.5 m s(-1)). Differences between conditions were detected with the general linear method (factorial model). Barefoot running is characterized by a significantly larger external loading rate than the shod condition. The flatter foot placement at touchdown is prepared in free flight, implying an actively induced adaptation strategy. In the barefoot condition, plantar pressure measurements reveal a flatter foot placement to correlate with lower peak heel pressures. Therefore, it is assumed that runners adopt this different touchdown geometry in barefoot running in an attempt to limit the local pressure underneath the heel. A significantly higher leg stiffness during the stance phase was found for the barefoot condition. The sagittal kinematic adaptations between conditions were found in the same way for all subjects and at the three running velocities. However, large individual variations were observed between the runners for the rearfoot kinematics.     

The structure of body measurements for the determination of shoe sizing for young Croatian men

The determination and promotion of the system of shoe sizing requires accurate knowledge of morphological properties of the foot and lower leg of the tested population. Similarly it is necessary to establish the occurrence and regional distribution of definite sizes in the tested population. Possible regional differences in morphological properties must not be ignored because it has been established by means of anthropological measuring that both foot dimensions and foot shapes differ between populations and within the same population. This has been proven by the investigation of body measures, carried out for the purpose of establishing a system of footwear sizes, which was executed on a randomly selected sample of 4,268 healthy and normally developed males aged 18-22. The investigation was carried out in 1993 on five locations each of which representing a definite region of the Republic of Croatia: Jastrebarsko (central), Koprivnica (northwestern), Pula (southwestern), Sinj (southern) and Pozega (northeastern). The measuring instrument was 31 foot and lower-leg sizes according to the existing ISO standards for footwear. Interregional differences are significant in all body measures. The role and the contribution of individual measures to these differences has been established by means of discriminatory analysis with regions as a priori defined samples. In order to constitute a convenient and purposeful standard for the footwear size system it is necessary to work out a database with referent values for the same system.     

Influence of phase I duration on phase II VO2 kinetics parameter estimates in older and young adults

Older adults (O) may have a longer phase I pulmonary O(2) uptake kinetics (Vo(2)(p)) than young adults (Y); this may affect parameter estimates of phase II Vo(2)(p). Therefore, we sought to: 1) experimentally estimate the duration of phase I Vo(2)(p) (EE phase I) in O and Y subjects during moderate-intensity exercise transitions; 2) examine the effects of selected phase I durations (i.e., different start times for modeling phase II) on parameter estimates of the phase II Vo(2)(p) response; and 3) thereby determine whether slower phase II kinetics in O subjects represent a physiological difference or a by-product of fitting strategy. Vo(2)(p) was measured breath-by-breath in 19 O (68 ± 6 yr; mean ± SD) and 19 Y (24 ± 5 yr) using a volume turbine and mass spectrometer. Phase I Vo(2)(p) was longer in O (31 ± 4 s) than Y (20 ± 7 s) (P < 0.05). In O, phase II τVo(2)(p) was larger (P < 0.05) when fitting started at 15 s (49 ± 12 s) compared with fits starting at the individual EE phase I (43 ± 12 s), 25 s (42 ± 10 s), 35 s (42 ± 12 s), and 45 s (45 ± 15 s). In Y, τVo(2)(p) was not affected by the time at which phase II Vo(2)(p) fitting started (τVo(2)(p) = 31 ± 7 s, 29 ± 9 s, 30 ± 10 s, 32 ± 11 s, and 30 ± 8 s for fittings starting at 15 s, 25 s, 35 s, 45 s, and EE phase I, respectively). Fitting from EE phase I, 25 s, or 35 s resulted in the smallest CI τVo(2)(p) in both O and Y. Thus, fitting phase II Vo(2)(p) from (but not constrained to) 25 s or 35 s provides consistent estimates of Vo(2)(p) kinetics parameters in Y and O, despite the longer phase I Vo(2)(p) in O.     

Evaluation of gait and slip parameters for adults with intellectual disability

Adults with intellectual disability (ID) experience more falls than their non-disabled peers. A gait analysis was conducted to quantify normal walking, and an additional slip trial was performed to measure slip response characteristics for adults with ID as well as a group of age- and gender-matched controls. Variables relating to gait pattern, slip propensity, and slip severity were assessed to compare the differences between groups. The ID group was found to have significantly slower walking speed, shorter step lengths, and increased knee flexion angles at heel contact. These gait characteristics are known to reduce the likelihood of slip initiation in adults without ID. Despite a more cautious gait pattern, however, the ID group exhibited greater slip distances indicating greater slip severity. This study suggests that falls in this population may be due to deficient slip detection or insufficient recovery response.     

A computational method for reliable gait event detection and abnormality detection for feedback in rehabilitation

In this paper, a gait event detection algorithm is presented that uses computer intelligence (fuzzy logic) to identify seven gait phases in walking gait. Two inertial measurement units and four force-sensitive resistors were used to obtain knee angle and foot pressure patterns, respectively. Fuzzy logic is used to address the complexity in distinguishing gait phases based on discrete events. A novel application of the seven-dimensional vector analysis method to estimate the amount of abnormalities detected was also investigated based on the two gait parameters. Experiments were carried out to validate the application of the two proposed algorithms to provide accurate feedback in rehabilitation. The algorithm responses were tested for two cases, normal and abnormal gait. The large amount of data required for reliable gait-phase detection necessitate the utilisation of computer methods to store and manage the data. Therefore, a database management system and an interactive graphical user interface were developed for the utilisation of the overall system in a clinical environment.     

A computational method for reliable gait event detection and abnormality detection for feedback in rehabilitation

In this paper, a gait event detection algorithm is presented that uses computer intelligence (fuzzy logic) to identify seven gait phases in walking gait. Two inertial measurement units and four force-sensitive resistors were used to obtain knee angle and foot pressure patterns, respectively. Fuzzy logic is used to address the complexity in distinguishing gait phases based on discrete events. A novel application of the seven-dimensional vector analysis method to estimate the amount of abnormalities detected was also investigated based on the two gait parameters. Experiments were carried out to validate the application of the two proposed algorithms to provide accurate feedback in rehabilitation. The algorithm responses were tested for two cases, normal and abnormal gait. The large amount of data required for reliable gait-phase detection necessitate the utilisation of computer methods to store and manage the data. Therefore, a database management system and an interactive graphical user interface were developed for the utilisation of the overall system in a clinical environment.     

Talocrural and talocalcaneal joint kinematics and kinetics during the stance phase of walking

The purpose of this investigation was to study the kinematics and kinetics of the joints between the leg and calcaneus during the stance phase of walking. The talocrural and talocalcaneal joints were each assumed to act as monocentric single degree of freedom hinge joints. Motion at one joint was defined by the relative rotation of a point on the opposing joint. The results, based upon the gait of three subjects, showed that the hinge joint assumption may be reasonable. A discrepancy in the kinematics was shown between the talocrural joint rotation and its commonly assumed sagittal plane representation, especially during initial flatfoot. This discrepancy is due to the fact that the sagittal plane rotation is created by the combined rotations of the talocrural and talocalcaneal joints. The talocalcaneal joint showed a peak 25-30 Nm supinatory moment at 80% of stance. The talocrural joint moment was qualitatively similar to the commonly measured sagittal plane moment, but the present results show that the sagittal plane moment overpredicted the true moment by 6-22% due to the two-dimensional assumption.