Effects of a Prosthetic Foot With Increased Coronal Adaptability on Cross-Slope Walking.

BACKGROUND: Walking on cross-slopes is a common but challenging task for persons with lower limb amputation. The uneven ground and the resulting functional leg length discrepancy in this situation requires adaptability of both user and prosthesis. OBJECTIVES: This study investigated the effects of a novel prosthetic foot that offers adaptability on cross-slope surfaces, using instrumented gait analysis and patient-reported outcomes. Moreover, the results were compared with two common prosthetic feet. METHODOLOGY: Twelve individuals with unilateral transtibial amputation and ten able-bodied control subjects participated in this randomized cross-over study. Participants walked on level ground and ±10° inclined cross-slopes at a self-selected walking speed. There were three prosthetic foot interventions: Triton Side Flex (TSF), Triton LP and Pro-Flex LP. The accommodation time for each foot was at least 4 weeks. The main outcome measures were as follows: frontal plane adaptation of shoe and prosthetic foot keel, mediolateral course of the center of pressure, ground reaction force in vertical and mediolateral direction, external knee adduction moment, gait speed, stance phase duration, step length and step width. Patient-reported outcomes assessed were the Activities specific Balanced Confidence (ABC) Scale, Prosthetic Limb Users Survey of Mobility (PLUS M) and Activities of Daily Living Questionnaire (ADL-Q). FINDINGS: The TSF prosthetic foot adapted both faster and to a greater extent to the cross-slope conditions compared to the Triton LP and Pro-Flex LP. The graphs for the mediolateral center of pressure course and mediolateral ground reaction force showed a distinct grouping for level ground and ±10° cross-slopes, similar to control subjects. In the ADL-Q, participants reported a higher level of perceived safety and comfort when using the TSF on cross-slopes. Eight out of twelve participants preferred the TSF over the reference. CONCLUSIONS: The frontal plane adaptation characteristics of the TSF prosthetic foot appear to be beneficial to the user and thus may enhance locomotion on uneven ground - specifically on cross-slopes.

Gait Characteristics of Transtibial Amputees on Level Ground in a Cohort of 53 Amputees - Comparison of Kinetics and Kinematics With Non-amputees.

STUDY DESIGN: Retrospective analysis. BACKGROUND: The gait characteristics of transtibial amputees (TTs) have been described many times. In general, the literature reported nearly consistent results for the kinematic and kinetic parameters of the prosthetic side. However, the literature revealed inconsistent findings on kinetic parameters for determining the risk of developing knee osteoarthritis, such as the peak knee adduction moment, knee flexion moment and vertical ground reaction forces. OBJECTIVES: The objective of our study was to describe the sagittal kinetic and kinematic gait characteristics of the ankle and residual knee joint of the prosthetic limb and the knee loading parameters of the sound side of unilateral TTs. This specific consideration may contribute to resolving the controversy of these parameters in the literature. METHODS: We analysed our database containing gait analyses from 53 unilateral TTs and compared data to a control group (CG), also taken from our database. The sagittal kinetic and kinematic gait characteristics of the ankle and residual knee joint of the prosthetic limb, and selected knee loading parameters of the sound side (the peak knee adduction moment, knee flexion moment and vertical ground reaction forces) were evaluated. Beside these parameters we reported typical spatiotemporal gait parameters as gait velocity, step length, step length asymmetry, stance phase duration and asymmetry of stance phase duration. RESULTS: The TTs walked slower and more asymmetrically than the CG. The kinematic pattern of the prosthetic ankle differed from that found in the CG. The largest difference was observed for the range of motion of the plantarflexion at push-off, which was significantly reduced for the prosthetic foot. The residual knee joint was generally affected with respect to decreased moments and reduced knee flexion during stance phase. The peaks of the vertical ground reaction forces and knee adduction moments showed no differences between the sound side of amputees and the CG. The peak knee flexion moment at midstance was significantly reduced for the sound side of amputees in comparison with the CG. CONCLUSION: The biomechanical data measured for the prosthetic side in a cohort of 53 unilateral TT amputees conformed with the literature. The parameters determining the risk of developing knee osteoarthritis investigated in our retrospective analysis were not increased on the sound side in comparison with non-amputees. We deem it reasonable to assume that an appropriate prosthesis will reduce the likelihood of overloading the knee on the sound side during normal walking.

A novel mechanotronic orthosis enables symmetrical gait kinematics in a patient with a femoral nerve palsy - a case study.

The usage of stance- and swing-phase control orthoses (SSCOs) is a good option in patients with neuromuscular insufficiency of the quadriceps muscle in a broad range of musculo-skeletal disorders. The subjective sensation of improved mobility in daily life and walking comfort could be objectively confirmed by the ability to walk without crutches and by harmonization of the gait patterns in hip and knee. They could also be a considered mobility device after limb salvage surgery, which may even have an impact on preoperative decision making. IMPLICATIONS FOR REHABILITATION Symmetric gate in spite of femoral nerve palsy. Early gate improvements even after hours. High patient?s motivation to use the device.

How long are the ends of polyene chains?

In this work we study conjugation in all-trans polyene chains H[Single Bond](HC[Double Bond]CH)(n)[Single Bond]H with a view to establishing the length scale for the interaction between conjugated double bonds. As a polyene oligomer is made longer, bond length alternation between formal carbon-carbon single and double bonds diminishes toward the middle of the chain, eventually reaching a constant value characteristic of an "infinite" chain. However those bonds near the end of the chain continue to be influenced by the end, even in the long-chain limit. We have determined optimized geometries for polyene oligomers with up to n=11 repeat units at the MP2/cc-pVTZ level. At this length the central-most bonds are almost converged to the long chain limit, for which we estimate R(C[Double Bond]C)=1.3652 A and R(C[Single Bond]C)=1.4238 A. In contrast, the endmost double bond has a length of 1.3442 A and the endmost single bond has a length of 1.4425 A. We find that a given bond is significantly influenced by conjugation paths through up to six neighboring conjugated double bonds. End effects can also be monitored by examining the energy increment per added monomer as the oligomer length is increased. This analysis also indicates that significant conjugation effects extend out through approximately six neighboring double bonds. From the energy per monomer of the longest chains we extract a value of about 8 kcal/mol for the extra stabilization energy per monomer due to conjugation in long chains.

Clar theory for radical benzenoids.

Eric Clar's ideas concerning "aromatic sextets" are extended from closed-shell benzenoids to the case of radical benzenoids, particularly those where the unpaired electrons are largely localized on sites of one "type" (starred or unstarred). A quantitative format in terms of a new Clar polynomial is introduced to make quantitative correlations with a selection of numerical data, including delocalization energies, spin densities, and energy gaps between states of different spin multiplicities. The correlations are generally quite good, thereby further validating Clar's ideas and our extension and quantification of them.

[Gait-analytical studies in patients treated by valgus tibial head osteotomy]. / Ganganalytische Untersuchungen von Patienten mit valgisierender Tibiakopfosteotomie.

So far, the use of imaging methods has been the only way of evaluating unicompartmental gonarthritis caused by malalignment of lower extremity axes and the results of operative correction. Unfortunately, radiological visualization does not give any information about the actual loads on the joint, i.e.the forces and moments acting on it under dynamic conditions. These can be determined by means of gait-analytical measurements. The authors explain how the anomalous loading that occurs in the knee joint in the case of varus gonarthritis can be calculated and assessed. The mean maximum varus moment of knee joints in a group of patients with varus deformity was 0.74 Nm\kg, which was significantly higher than that in a control group (0.63 Nm\kg). Even after correction of the axes, increased maximum moments--some of them independent of the angle of the knee and of the correction angle--were observed in 30% of the cases investigated. These cases were found to be characterized by a predisposition to revarization. Knee joints in which the preoperative varus moment was significantly high or there was a tendency to under-correction were especially likely to show these features. For these reasons, valgus tibial head osteotomies should generally be performed with slight overcorrection. If the preoperative gait analysis has already confirmed that significantly increased varus forces are in play, a definite overcorrection to about 5 degrees beyond the physiological angle should be the aim.

[Functional results of dynamic gait analysis after 1 year of hobby-athletes with a surgically treated ankle fracture]. / Funktionelle Ergebnisse bei Freizeitsportlern in der dynamischen Ganganalyse 1 Jahr nach operativ versorgten Sprunggelenkfrakturen.

Retrospectively 20 patients with a surgically treated ankle fracture caused by hobby-accidents were examined clinically and radiologically by a score modified to Phillips after 12 months postoperatively. Further they have taken part in a dynamical gait analysis at the same time. A group of 20 healthy adults was used as a control group comparable to age, sex, height and weight. Although 19 patients out of 20 have achieved a good result at the score evaluation and none of them was clinically noticed with any pathological gait, gait analysis has shown a significant slowed gait speed and a decreased stride length. The reduction of the plantarflexor moment at the injured ankle joint immediately following heel contact was yet the most remarkable result of the gait analysis. The changes of gait pattern are interpreted as an adapted and internalized motion pattern caused by pain and behaviour of rest at any time while the mobilisation-phase was going on. It could not document any significant correlation between subjective and clinical parameters and parameters registered by gait analysis. However, a significant correlation of gait-analysed parameters was found between the injured and uninjured side. By dynamical gait analysis it is possible to quantify remarkable gait changes, to obtain objective data, but also to demonstrate asymmetrical loading and motion that were not clinically detectable previously. It follows that it can be relevant to patients with complaints by leading them to specific physiotherapeutical treatment and gait training so that they would be able to carry on their sports-activities again.

[Significance of static prosthesis alignment for standing and walking of patients with lower limb amputation]. / Die Bedeutung des statischen Prothesenaufbaus für das Stehen und Gehen des Unterschenkelamputierten.

The influence of three alignment parameters of a transtibial prosthesis (sagittal foot position, plantar flexion, mediolateral foot position) on the load and motion of the lower extremity joints was investigated in 13 unilateral transtibial amputees. The aim was to determine whether a correlation exists between static prosthetic alignment and gait pattern that would allow an optimal biomechanical prosthetic alignment. The gait pattern was measured using kinematic, kinetic, and electromyographic methods. Statics was defined using the alignment apparatus L.A.S.A.R. Posture. The electromyogram of the m. vastus lateralis and m. biceps femoris was recorded on both sides. The motion of joints is described by joint angles. External joint moments define the mechanical loads. Alignment has almost no influence on muscle activity and joint mechanics of the contralateral leg. In contrast, prosthetic alignment affects clearly and systematically the load and motion of the knee joint during the stance phase on the ipsilateral side. The sagittal foot position influences the maximal flexion angle in the stance phase. The plantar flexion of the foot affects the temporal structure of knee motion. The mediolateral foot position causes correspondingly different varus and valgus moments acting on the knee. Swing phase motion does not depend on prosthetic alignment. The iEMG of the m. vastus lateralis is reduced. Innervation characteristics of the m. biceps femoris on the prosthetically fitted leg has completely changed. The ischiocrural muscles take over the neuromuscular action of the m. gastrocnemius to compensate for the external knee extension moment during the second part of the stance phase. Prosthetic statics determines if the knee joint is physiologically stressed in a standing posture and during walking. Statics will be correct if the anatomical knee axis of the standing amputee is located about 15 mm posterior to the load line in the sagittal plane. In the frontal plane, the load line touches the lateral patella border and strikes the middle of the foot about 5 cm anterior to the adapter. During walking, attention should be paid to performance of knee flexion in the stance phase.

Selective thigh muscle atrophy in trans-tibial amputees: an ultrasonographic study.

In trans-tibial amputees, PTB (patellar tendon bearing) prostheses provide almost physiological mobility of the knee joint in the sagittal plane. Nevertheless, there are characteristic adaptations of the knee joint muscles. Myosonography is a suitable method for depicting muscle atrophy and hypertrophy due to muscle dysfunction. The present study was intended to assess anatomical alterations of thigh muscles in trans-tibial amputees wearing a PTB prothesis. Thicknesses and cross-sectional areas of the quadriceps femoris, sartorius, gracilis, semitendinosus and biceps femoris muscles were determined ultrasonographically on both limbs in 17 amputees with a PTB prothesis. The gait was analysed using an optoelectronical system, force plates and surface electromyography of the vastus lateralis and biceps femoris muscles. Quadriceps femoris and sartorius muscles of the amputated extremity exhibited significant atrophy compared with the contralateral limb (reduction of muscle thickness ranged between 11.7% and 30.4%), whereas the gracilis and hamstring muscles were not significantly affected. Even the quadriceps femoris muscle of the non-amputated limb showed a slight atrophy compared with a reference group. Increased echointensities were found predominantly in the quadriceps muscle on the amputated leg. During gait, electromyographical activity within the amputated limb was reduced in the vastus lateralis and increased in the biceps femoris muscle. Even long-term adaptation to PTB prostheses results in characteristic deviation from normal gait. Atrophy occurs in the ventral thigh muscles, predominantly on the amputated leg, whereas the dorsal thigh muscles are hardly affected, probably due to compensatory hyperactivity.

Curvature matching and strain relief in bucky-tori: usage of sp3-hybridization and nonhexagonal rings.

The relief of different types of curvature strain in bucky-tori of elemental carbon is considered in a general formal framework. This theory then is used to aid in the design of several structures, which are treated via molecular mechanics. Novel illustrations of the remnant strain are made, and some modest conclusions as to the nature of the structure of the experimentally observed bucky-tori are suggested.

Effects of sagittal plane prosthetic alignment on standing trans-tibial amputee knee loads.

The influence of sagittal plane prosthetic alignment changes on loads applied to the ispilateral knee was investigated using 5 transtibial amputee subjects. The goal was to determine which prosthetic alignment results in the most energy efficient standing and also minimises stresses on knee structures during standing. The electromyogram, the external mechanical loading of the prosthetic leg and the amputees' posture were recorded for a wide range of prosthetic alignments. The EMG of the vastus lateralis and biceps femoris muscles was measured bilaterally; the EMG of the gastrocnemius muscle was measured only on the contralateral side. The distance between the anatomical knee centre and each individual's load line, as determined by the Otto Bock "L.A.S.A.R. Posture" alignment system, was used as a measure of the mechanical load applied to the knee joint. Prosthetic alignment has almost no influence on muscle activity of the contralateral lower limb during static standing. On the other hand, prosthetic alignment has a significant influence on the load applied to the amputee's ipsilateral knee joint. The external knee moments applied to the knee ligaments and knee muscles on the amputated side change systematically in response to different plantar flexion or dorsiflexion angles of the prosthetic ankle-foot. During standing the extensor muscles stabilise the limb by contracting if the load line is located less than 15 mm anterior to the anatomical knee centre. The biceps femoris muscle appears to have little or no protective function against hyperextension during standing even if large external knee extension moments are caused by excessive plantar flexion. Such extreme alignments significantly increase the stresses on knee ligaments and the posterior knee capsule. When prosthetic sagittal plane alignment is altered, the trans-tibial amputee compensates by balancing the upper part of the body over the centre of pressure of the prosthetic foot. Biomechanically optimal alignment of the trans-tibial prosthesis occurs when the individual load line is approximately 15 mm anterior to the anatomical knee centre, permitting a comfortable, energy efficient standing and minimising the mechanical loading on the knee structures.

Chemical sub-structural cluster expansions for molecular properties.

Abstract The correlation of different molecular sub-structures with various molecular properties has a long history, of over a century. And currently such structural characterizations still remain of central interest in chemistry. Thus a general formalism to analyze a property or activity in terms of sub-structural contributions is of interest, and is pursued here. The approach may indeed be viewed as a formalization and extension of standard bond-energy ideas as arise even in introductory chemistry courses. The present formalism allows for: • a more complete and comprehensive formulation, with higher-order corrections to achieve greater accuracy; • a more general form for the class of sub-structures appearing in the expansion, thereby allowing more general (e.g., "multiplicative") properties to be expanded; and • a more general form for the expansion functions, thereby allowing more rapid convergence rates for the expansions. An illustrative example for the structure/property correlation of conjugated-hydrocarbon π-energy is made. Some comments on the use for describing bio-activities, and in particular toxicities, are made.

[Evaluation with biomechanical gait analysis of various treatment methods after rupture of the anterior cruciate ligament]. / Biomechanisch-ganganalytische Bewertung verschiedener Behandlungsmethoden nach Ruptur des vorderen Kreuzbandes.

The purpose of the present study is to evaluate the rehabilitation of different treatments of ACL ruptured knees by means of gait parameters. The gait analysis results in two surgically treated patient groups (patellar tendon autograft reconstructions (n = 35) and augmented repairs (n = 15) and one non-surgically treated patient group (n = 19) are evaluated by means of gait parameters of normal controls (n = 30). The technical equipment included an optoelectronic system for recording the kinematics of gait (Primas, NL) and two force plates for measuring the ground reaction forces (Kistler, CH). The moments acting on joints can be determined experimentally with both systems. It can be shown from special gait tests that the derived quantitative evaluation parameters are independent from the gait analysis conditions. One year after surgery, both the patellar tendon autograft reconstruction group and the augmented repair group show clear deficiencies in gait parameters compared with the controls. In particular this concerns the midstance extension motion of the knee (p < = 0.01) and the extension moments acting on the knee joint during the stance phase (sagittal plane, p < = 0.01). The deficiencies of both surgically treated groups are approximately the same. However, one year after occurrence of the disruption the non-surgically treated group cannot be distinguished from the controls. From this and from additional pre-surgical measurements, it can be concluded, that operating has an important influence on gait parameters. The role of the gait analysis results has been discussed.

Assessment of isometric contractions performed with maximal subjective effort: corresponding results for EEG changes and force measurements.

In order to find a parameter or parameters that can be attributed to movements performed with maximal subjective effort, EEG recordings and force measurements were taken in connection with isometric muscle contractions performed with 80% of the subjective maximal force (IMC80) or with maximal subjective effort (IMC100). Criteria based on EEG recordings and force measurements have been considered as indicators for maximal subjective effort in a given movement. The following criteria were selected: A. If the mean spectral theta amplitude across the parieto-occipital area decreases from IMC80 to IMC100 then the isometric contraction is taken to be performed with maximal effort; B. If the obtained force values can be fitted to a switch function and if the achieved forces are only a predetermined percentage lower than the maximal force value obtained over all trials then this isometric contraction is accepted to be performed with maximal effort. 18 out of 24 cases fulfill the EEG criterion whereas the criterion for force measurements is fulfilled in 16 out of 24 trials. The comparison between the results obtained by means of the EEG criterion and by means of criterion for force measurement shows that the results are in agreement in 22 out of 24 cases (p < .001). The high correspondence of the assessments allows us to suspect that both criteria specify the same phenomenon, namely the performance of a motor task with maximal subjective effort.

Theta power decreases in preparation for voluntary isometric contractions performed with maximal subjective effort.

In order to find EEG parameters that can be attributed to movements performed with maximal subjective effort, EEG recordings and force measurements were realized in connection with isometric contractions (IMC). IMC were performed with submaximal and maximal subjective effort. Mean spectral power density within the theta band was found as an indicator for maximal subjective effort. The theta power across the parieto-occipital area decreases from rest through movements performed with submaximal force to movements performed with maximal effort. It is argued that this theta decrease possibly reflects a down-regulation of the posterior attention system in order to minimize the influences of external stimuli during the preparation for voluntary IMC performed with maximal subjective effort.