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Limited biomechanical data exist describing how yoga asanas (postures) load the limbs and joints, and little evidence-based recommendations for yoga injury prevention are available. This study aimed to establish joint loading metrics for an injury-prone, yet common yoga pose, the Triangle asana (Trikonasana) by identifying how stance width adjustments alter lower extremity loading.Eighteen yoga practitioners underwent 3D motion analysis while performing Trikonasana with self-selected (SS) stance width and -30, -20, -10, +10, +20, and +30% of SS stance width. Ground reaction forces (GRFs), joint forces, and joint moments were calculated for the leading and trailing limb ankle, knee, and hip. One-way repeated-measures analysis of variance determined differences in loading due to stance width.GRFs, net joint forces, and net joint moments were significantly affected by stance width where increasing stance width increased leading limb loading but decreased trailing limb loading.Altering stance width of Trikonasana influences lower extremity limb loading, and these loading responses were limb-dependent. Yoga practitioners and instructors can use this information to objectively support increasing or decreasing stance width to reduce or increase limb loading according to their goals or to make accommodations to groups such as beginners or at-risk populations for safer, more accessible yoga practices. Cuing a wider or narrower stance width will not have the same effect on both limbs.

Background Variations in vertical loading rates have been associated with overuse injuries of the lower extremity; however, they are typically collected using 3-dimensional motion capture systems and in-ground force plates not available to most clinicians because of cost and space constraints. Purpose The purpose of this study was to determine if kinetic measures commonly used to describe lower extremity loading characteristics could be estimated from step rate and specific sagittal plane kinematic variables captured using 2-dimensional motion analysis during treadmill running. Study design Observational Study. Methods Ten high school cross-country runners (4 men and 6 women) voluntarily consented to participate in this study. Reflective markers were placed on each lower extremity over multiple anatomical landmarks. Participants were then asked to run on the instrumented treadmill at their preferred running speed. When the participants indicated they were in their typical running pattern, they continued to run at their preferred speed for a minimum of five minutes. After three minutes of running at their preferred running speed, the participant's step rate was counted and after running for four minutes, video and ground reaction force data were recorded for 60 sec. All running motion data were recorded using a single high-speed camera at 240 frames per second and ground reaction force data were sampled at 1000 Hz. Results Mean kinematic values between the left and right extremities for all 10 participants were not significantly different. Consequently, data for the left and right extremities were grouped for all further analyses. The stepwise forward regression to predict vertical ground reaction force resulted in a five-variable model (step rate and four kinematic variables) with R2 = 0.56. The stepwise forward regression to predict average loading rate also resulted in a five kinematic variable model with R2 = 0.51. Conclusions Step rate and sagittal plane kinematic variables measured using a simplified 2-dimensional motion analysis approach with a single high-speed camera can provide the clinician with a reasonable estimate of ground reaction force kinetics during treadmill running. Level of evidence 4, Controlled laboratory study.

Running is beneficial for physical, social, and emotional health, and participating in physical activity, including running, is becoming more popular for people with an amputation. However, this population has a greater risk of falling relative to people without an amputation, which may be a barrier to running. Understanding how dynamic balance is maintained during running is important for removing this barrier. To investigate dynamic balance, we quantified whole-body angular momentum in eight people with a unilateral transtibial amputation (TTA) using running-specific prostheses (RSPs) compared to eight people without TTA during running at 2.5, 3.0, and 3.5 m/s. People with TTA had greater ranges of whole-body angular momentum compared to people without TTA in the frontal and sagittal planes (p 0.01). These greater ranges resulted from smaller peak medial, lateral, and braking ground reaction forces from the amputated leg compared to the intact leg and people without TTA. Reduced RSP mass relative to the biological leg also influenced whole-body angular momentum as evidenced by smaller ranges of amputated leg angular momentum compared to the intact leg in the frontal and sagittal planes. Smaller amputated leg angular momentum corresponded with smaller contralateral arm angular momentum in the sagittal plane (p 0.01). People with TTA maintain balance during running with altered muscle coordination and prosthesis characteristics. Restoring mediolateral force generation through prosthetic design advances may help in regulating the frontal plane component of whole-body angular momentum for people with TTA, with potential to improve their ability to maintain balance during running.

People with unilateral transtibial amputations (TTA) have greater risks of bilateral hip osteoarthritis, related to asymmetric biomechanics compared to people without TTA. Running is beneficial for physical health and is gaining popularity. However, people with TTA may not have access to running-specific prostheses (RSPs), which are designed for running, and may instead run using their daily-use prosthesis (DUP). Differences in joint loading may result from prosthesis choice; thus, it is important to characterize changes in peak and impulsive hip joint contact loading during running. Six people with and without TTA ran at 3.5 m/s while ground reaction forces, kinematics, and electromyography were collected. People with TTA ran using their own RSP and DUP. Musculoskeletal models incorporating prosthesis type of each individual were used to quantify individual muscle forces and hip joint contact forces (HJCFs) during running. People using RSPs had smaller bilateral peak hip joint contact forces compared to when wearing DUPs during stance and swing, and a smaller impulse over the entire gait cycle. Greater amputated leg peak hip joint contact forces for people wearing DUPs compared to RSPs occurred with greater forces from the ipsilateral gluteus maximus during stance. People with TTA also had greater bilateral peak hip joint contact forces during swing compared to people without TTA, which occurred with greater peak gluteus medius forces. Running with more compliant RSPs may be beneficial for long-term joint health by reducing peak and impulsive hip loading compared to DUPs.

Objective The objective of this study was to investigate three-dimensional lower extremity joint moment differences between limbs and speed influences on these differences in individuals with lower extremity amputations using running-specific prostheses. Design Eight individuals with unilateral transtibial amputations and 8 control subjects with no amputations ran overground at three constant velocities (2.5, 3.0, and 3.5 m/sec). A 2 × 2 × 3 (group × leg × speed) repeated-measures analysis of variance with Bonferroni adjustments determined statistical significance. Results The prosthetic limb generated significantly greater peak ankle plantarflexion moments and smaller peak ankle varus, knee stance extension, knee swing flexion, knee internal rotation, hip stance flexion, hip swing flexion, hip swing extension, hip valgus, and hip external rotation moments than the intact limb did. The intact limb had greater peak hip external rotation moments than control limbs did, but all other peak moments were similar between these limbs. Increases in peak hip stance and knee swing flexion moments associated with speed were greater in the intact limb than in the prosthetic limb. Conclusion Individuals with amputation relied on the intact limb more than the prosthetic limb to run at a particular speed when wearing running-specific prostheses, but the intact joints were not overloaded relative to the control limbs.

People with unilateral transtibial amputation (TTA) have biomechanical differences between the amputated and intact legs and compared to people without TTA during running. Additional biomechanical differences emerge between running with running-specific (RSPs) and daily-use prostheses (DUPs), but the associated underlying muscle activity is unclear. We collected surface electromyography from the biceps femoris long head, rectus femoris, vastus lateralis, and gastrocnemius as well as body kinematics and ground reaction forces in six people with and six people without TTA. We compared stance phase muscle activity and peak activation timing in people with and without TTA and between people using RSPs compared to DUPs during running at 3.5 m/s. Peak amputated leg hamstring activity occurred 34% (RSP) and 31% (DUP) earlier in stance phase compared to the intact leg. Peak amputated leg rectus femoris activity of people wearing DUPs occurred 8% and 9% later in stance phase than the intact leg of people wearing DUPs and amputated leg of people wearing RSPs, respectively. People with TTA had 45% (DUP) and 61% (RSP) smaller peak amputated leg knee extension moments compared to people without TTA, consistent with observations of quadriceps muscle activity. Using RSPs decreased overall muscle activity compared to DUPs.

Background Understanding the potential risks of running-related injuries in unilateral transfemoral amputees contributes to the development and implementation of the injury prevention programme in running gait rehabilitation. We investigated the vertical ground reaction force loading in unilateral transfemoral amputees who used running-specific prostheses across a range of running speeds. Methods Ten unilateral transfemoral amputees and ten non-amputees performed running trials on an instrumented treadmill at the incremental speeds of 30, 40, 50, and 60% of their maximum acquired speeds. Per-step and cumulative vertical instantaneous loading rates were calculated from the vertical ground reaction force in the affected, unaffected, and non-amputated control limbs. Findings Both the per-step and cumulative vertical instantaneous loading rates of the unaffected limbs in runners with unilateral transfemoral amputation were significantly greater than the affected and non-amputated control limbs at all speeds. Interpretation The results of the present study suggest that runners with unilateral transfemoral amputation may be exposed to a greater risk of running-related injuries in their unaffected limbs compared to the affected and non-amputated control limbs.

Some individuals with a transtibial amputation (TTA) may not have access to running-specific prostheses and therefore choose to run using their daily-use prosthesis. Unlike running-specific prostheses, daily-use prostheses are not designed for running and may result in biomechanical differences that influence injury risk. To investigate these potential differences, we assessed the effect of amputation, prosthesis type, and running speed on joint work and ground reaction forces. 13 people with and without a unilateral TTA ran at speeds ranging from 2.5 m/s to 5.0 m/s. People with TTA ran using their own daily-use and running-specific prostheses. Body kinematics and ground reaction forces were collected and used to compute joint work. People with TTA had smaller peak braking, propulsive and medial/lateral ground reaction forces from the amputated leg compared to people without TTA. People wearing running-specific prostheses had smaller peak amputated leg vertical ground reaction forces compared to daily-use prostheses at speeds above 3.5 m/s. Medial/lateral forces were also smaller in running-specific prostheses, which may present balance challenges when running on varied terrain. Running-specific prostheses stored and returned more energy and provided greater propulsion, resulting in more similar positive hip work between legs compared to daily-use prostheses. Increases in positive hip work, but not device work, highlight the importance of the hip in increasing running speed. Running-specific devices may be beneficial for joint health at running-speeds above 3.5 m/s and provide advantages in propulsion and energy return at all speeds compared to daily-use prostheses, helping people with TTA achieve faster running speeds.

Objectives (1) To test the validity of a trifilar pendulum in estimating moments of inertia (MOIs) for running-specific prostheses (RSPs), (2) to measure inertial properties (mass, center of mass [CM] position, and MOIs) for 4 RSPs, (3) to verify the influence of the stiffness on the inertial properties of RSPs, and (4) to develop a predictive equation to estimate RSP CM positions. Design An aluminum block with known MOIs was used for verifying the accuracy of the trifilar pendulum MOI measurements. MOI errors were investigated by systematically misaligning the block and pendulum principal axes across a range of 1 to 10cm. Mass, CM position, and MOI were tested across 4 RSP designs with 3 stiffness categories each. Setting University biomechanics laboratory. Specimens Four different RSP designs and 3 stiffness categories per design were examined. Interventions Not applicable. Main Outcome Measures MOI errors from known values and principal axis misalignments between RSPs and pendulum; mass, CM positions, and RSP principal axis MOIs; and predictive equation CM position errors. Results The trifilar pendulum estimated MOIs within −6.21×10 −5 kg/m 2 (≤1% error) for a block with known MOIs. Misalignments of 1 to 5cm between the RSPs' and pendulum's CM yielded errors from .00002 to .00113 kg/m 2 (0.3%−59.2%). Each RSP's inertial properties are presented. MOIs about any axis varied 2 across stiffness categories; MOIs differed up to .013kg/m 2 between different designs. The predictive CM equation erred between .010 and .028m when using average input values across an RSP design. Conclusions Trifilar pendulums can accurately measure RSP MOI. The RSP inertial properties differed slightly across stiffness categories within each design, but differed more substantially across different RSP designs. Using a predictive equation to estimate RSP CM positions can provide adequate data, but directly measuring CM positions is preferable.

Compared to intact limbs, running-specific prostheses have high resonance non-biologic materials and lack active tissues to damp high frequencies. These differences may lead to ground reaction forces (GRFs) with high frequency content. If so, ubiquitously applying low-pass filters to prosthetic and intact limb GRFs may attenuate veridical high frequency content and mask important and ecologically valid data from prostheses. To explore differences in frequency content between prosthetic and intact limbs we divided signal power from transtibial unilateral amputees and controls running at 2.5, 3.0, and 3.5m/s into Low (10Hz), High (10-25Hz), and Non-biologic (25Hz) frequency bandwidths. Faster speeds tended to reduce the proportion of signal power in the Low bandwidth while increasing it in the High and Non-biologic bandwidths. Further, prostheses had lower proportions of signal power at the High frequency bandwidth but greater proportions at the Non-biologic bandwidth. To evaluate whether these differences in frequency content interact with filter cut-offs and alter results, we filtered GRFs with cut-offs from 1 to 100Hz and calculated vertical impact peak (VIP). Changing cut-off had inconsistent effects on VIP across speeds and limbs: Faster speeds had significantly larger changes in VIP per change in cut-off while, compared to controls, prosthetic limbs had significantly smaller changes in VIP per change in cut-off. These findings reveal differences in GRF frequency content between prosthetic and intact limbs and suggest that a cut-off frequency that is appropriate for one limb or speed may be inappropriate for another.

Individuals with lower extremity amputation must adapt the mechanical interactions between the feet and ground to account for musculoskeletal function loss. However, it is currently unknown how individuals with amputation modulate three-dimensional ground reaction forces (GRFs) when running. This study aimed to understand how running with running-specific prostheses influences three-dimensional support forces from the ground. Eight individuals with unilateral transtibial amputations and 8 control subjects ran overground at 2.5, 3.0, and 3.5 m/s. Ten force plates measured GRFs at 1000 Hz. Peak and average GRFs and impulses in each plane were compared between limbs and groups. Prosthetic limbs generated reduced vertical impulses, braking forces and impulses, and mediolateral forces while generating similar propulsive impulses compared with intact and control limbs. Intact limbs generated greater peak and average vertical forces and average braking forces than control subjects’ limbs. These data indicate that the nonamputated limb experiences elevated mechanical loading compared with prosthetic and control limbs. This may place individuals with amputation at greater risk of acute injury or joint degeneration in their intact limb. Individuals with amputation adapted to running-specific prosthesis force production limitations by generating longer periods of positive impulse thus producing propulsive impulses equivalent to intact and control limbs.

Since the start of the wars in Afghanistan and Iraq, there have been 866 major limb amputations from combat operations seen at major military medical centers in the United States. These injuries have challenged rehabilitation professionals with many clinical problems. One such challenge is treating patients who sustain multiple limb amputations that involve both an upper extremity (UE) and a lower extremity (LE). This uncommon amputation pattern describes 27 patients of the aforementioned total. This article is a case study of a multiple limb amputee whose primary rehabilitation goal was to walk without the aid of an assistive devise. The primary objective is to discuss how wearing a UE prosthesis affects gait in comparison with not wearing the prosthesis. There were notable temporal-spatial and kinematic differences in the patient’s gait while wearing the UE prosthesis when compared with walking without it. For example, while wearing the UE prosthesis, the patient’s trunk rotated more toward his intact side but lateral flexion became more symmetric. For this patient, wearing a UE prosthesis had a desirable effect on trunk kinematics while ambulating. (J Prosthet Orthot. 2008; 20:163–166.) KEY INDEXING TERMS: gait, amputation, prosthesis, upper extremity

To investigate the impact of locomotor treadmill training with partial body-weight support (BWS) before the initiation of overground gait for adults less than 6 weeks poststroke.Parallel group, posttest only.Inpatient rehabilitation center.Adults after first stroke admitted to an inpatient rehabilitation unit: treadmill group (n=7) and comparison group (n=7).Locomotor treadmill training with partial BWS or traditional gait training methods.Gait kinematics, symmetry, velocity, and endurance at least 6 months postinsult.Data from 3-dimensional gait analysis and 6-minute walk test (6MWT) supported improved gait for adults postacute stroke who practiced gait on a treadmill before walking over ground. Gait analysis showed increased knee flexion during swing and absence of knee hyperextension in stance for the treadmill group. In addition, more normal ankle kinematics at initial contact and terminal stance were observed in the treadmill group. Improved gait symmetry in the treadmill group was confirmed by measures of single support time, hip flexion at initial contact, maximum knee flexion, and maximum knee extension during stance. The treadmill group also walked further and faster in the 6MWT than the comparison group.Application of locomotor treadmill training with partial BWS before overground gait training may be more effective in establishing symmetric and efficient gait in adults postacute stroke than traditional gait training methods in acute rehabilitation.

The motor learning literature is replete with studies investigating the contextual interference (CI) effect. However, CI research has focused on performance outcome measures, largely ignoring the influence varying levels of CI may have on performance production measures, particularly with tasks involving inter-limb coordination. It was the purpose of this study to explore the effects of three levels of CI on both categories of performance measures in adults who were naïve to a sport skill Participants were taught the basic movement pattern of two golf strokes the putt and pitch. Following an instructional period, subsequent practice involved 160 trials performed under low, moderate, or high CI. No significant group differences emerged from practice data. Analysis of post-test data indicated that the high CI group was generally superior on both production measures. These results add to a limited body of research that suggests CI can benefit the development of coordinated movements.

Background: Arthrodesis of the first metatarsophalangeal (MTP) joint is a common procedure with a proven long-term success rate. However, there is limited scientific information on its functional results. There is little data in the literature about changes in gait parameters after first MTP joint arthrodesis. The purpose of this study was to objectively evaluate the effects of first MTP joint arthrodesis on gait. Methods: Twenty-three patients with symptomatic hallux rigidus refractory to nonoperative treatment were treated with first MTP joint arthrodesis. A prospective gait analysis study was performed on all patients at an average of 8.6 days before surgery and then again at least 1 year postoperatively. Preoperative and postoperative data from the patients were compared to determine differences in clinically relevant temporal-spatial, kinematic, and kinetic parameters of gait. Results: There were three statistically significant changes in gait: increases in maximal ankle push-off power and single-limb support time on the involved extremity, and a decrease in step width. Conclusions: First MTP joint arthrodesis produces objective improvement in propulsive power, weightbearing function of the foot, and stability during gait.

Background: The effectiveness of total contact casts is postulated to be due to the reduction of plantar pressure. We investigated plantar loads to evaluate the mechanism by which total contact casts off-load the plantar surface of the foot to determine if it is the intimate molding of the weightbearing plantar surface or if a below-knee cast is necessary. Methods: Plantar pressures and forces in a total contact cast (TCC) were recorded in 12 healthy subjects, using the Pedar® (Novel GmbH, Munich, Germany) pedobarographic system. The measurements were repeated after removal of the ‘shank’ portion of the cast (proximal to malleoli), leaving in effect, a well-molded shoe-cast (SC). Measurements included average force and peak pressure. All parameters were measured under two different loading conditions: single-leg standing balanced on the casted limb and over-ground walking. To assess the contribution of calf geometry, the ‘calf ratio’ was calculated by dividing the largest by the smallest circumferences of the calf. All parameters were compared between TCC and SC for each subject in each of the two conditions. Paired t-tests were used to evaluate significance, which was set at a level of p < 0.006 due to the Bonferroni Correction. Results: Removal of the shank portion of the TCC significantly increased the average plantar force by 31% during walking. The force only increased 9% during standing, which was not significant. Peak pressure increased 53% after removal of the shank portion of the TCC during walking. Peak pressure was not significantly different during standing on one limb. No correlation was found between the calf ratio and the magnitude of change in the measured values. Conclusions: These results help to partially explain the widely recognized clinical observation that molded insoles and shoes, no matter how well conformed to the foot, do not reduce plantar loads as effectively as a total contact cast. The mechanism appears to be a critical unloading function of the proximal, ‘shank’ portion of the cast, presumably due to reduction in ankle motion.

The purpose of this study was to propose a new method that can be used to calculate electromechanical delay (EMD) without the measurement of forces. A secondary purpose, as an example of the importance of measuring EMD, was to predict muscle force development events based on the EMG activity of selected muscles during cycling at different pedaling frequencies. EMD was estimated using newly derived equations based on activation dynamics hypothesis. Tibialis anterior (TA) and soleus (SL) muscles of 16 male participants were studied while subjects pedaled at targeted cadences of 60, 80, and 100 revolutions per minute. The estimated EMDs of TA and SL were significantly different from each other with means of 68.1 and 88.7 ms, respectively. The average crank angle for the initiation and time to peak TA contraction was estimated at 75 +/- 35 degrees and 26 +/- 15 degrees before the crank reached top-dead-center (TDC), while the contraction ended at 31 +/- 19 degrees after the TDC on average. The projected starting, peak and end angles of SL contraction activity were 45 +/- 18 degrees , 123 +/- 13 degrees, and 218 +/- 35 degrees after the TDC, respectively. There was no difference among different pedaling cadences observed for these mechanical events. The proposed method was proven to be effective in studying EMD and estimate muscle contraction patterns during cycling.

The purpose of this study was to investigate the effect on gait in patients who underwent reconstruction for stage II posterior tibial tendon (PTT) dysfunction. Twelve patients with stage II PTT dysfunction underwent surgical reconstruction consisting of debridement of the posterior tibial tendon, flexor digitorum longus tendon transfer to the navicular tuberosity, medial displacement calcaneal osteotomy, and spring ligament reconstruction. Midfoot arthrodesis was performed in six patients and gastrocnemius recession in three. Gait analysis was performed 2 weeks prior to surgery and 1 year postoperatively. Preoperative and postoperative data were compared to determine differences in temporal-spatial parameters, lower limb kinematics, and ankle push-off power. Step length for the operated side increased from 52.6 ± 9.6 cm before the surgery to 57.5 ± 7.1 cm after the surgery ( p = .048). Cadence improved from 100.2 ± 10.7 steps/min to 109.1 ± 8.5 steps/min ( p = .05), thus increasing velocity from 87.6 ± 22.6 cm/s to 103.4 ± 15.9 cm/s ( p = .042). Single support percentage was unchanged. Maximum sagittal ankle joint power at push-off increased from 0.79 ± 0.35 W before surgery to 1.2 ± 0.5 W after surgery ( p = .042). There were statistically significant improvements in all radiographic parameters studied. This is the first prospective study to evaluate the in vivo effects on gait in patients undergoing this common surgical procedure. Analysis demonstrated statistically significant improvement in kinetic and kinematic parameters of gait function.

0.80 0.30 15.3 8.2 37.9 6.0 Cluster 9 0.9 0.2 13.6 5.2 0.61 0.40 33.3 6.4 39.0 8.8 involvement by showing a discrete foot drop during swing phase. The ankle of patients in cluster 3 was in plantar flexion during the main part of the gait cycle. Because of the characteristics this cluster was called reversed second ankle rocker with premature knee extension. Cluster 4, double bump with jump knee, was characterised by a double bump pattern at the ankle and an increased flexion at the hip (p4/1, 4/5, 4/7, 4/8 and 4/9 < 0.001) and the knee. Patients of cluster 5 were presented with a recurvatum knee. These children walked slower (significantly different between all clusters p < 0.001 except for cluster 9) compared to normal subjects, with a clearly decreased ankle power generation at push off (p5/1, 5/2, 5/3, 5/4, 5/6 and 5/7 < 0.001). Cluster 6 was characterised by a neutral to dorsiflexed ankle, with a double bump pattern in the sagittal plane. Therefore this cluster was called apparent equinus. Due to the reversed second ankle rocker, these patients had a large power absorption at the ankle at midstance (p6/2, 6/4, 6/7 and 6/8 < 0.001). Several features of cluster 6 indicated a stiff knee pattern and a flexed hip. Cluster 7, mild crouch, demonstrated an increased dorsiflexion at loading response (p7/1, 7/2, 7/3, 7/5 and 7/9 < 0.001). Also typical for this group was the increased knee flexion throughout the stance phase. The most outstanding feature of cluster 8 was the severe crouch pattern. Furthermore the ankle showed a lack of plantar flexion during the gait cycle (p8/2, 8/3, 8/5 and 8/9 < 0.0001). Patients in cluster 9 demonstrated continuous plantar flexion at the ankle and flexion at the hip and knee, and could therefore be described as a typical triple flexion pattern. The S.D. and mean of five important parameters were illustrated in Table 1.

Carbon fiber running-specific prostheses (RSPs) have allowed individuals with lower extremity amputation (ILEA) to actively participate in sporting activities including competitive sports. In spite of this positive trait, the RSPs have not been thoroughly evaluated regarding potential injury risks due to abnormal loading during running. Vertical impact peak (VIP) and average loading rate (VALR) of the vertical ground reaction force (vGRF) have been associated with running injuries in able-bodied runners but not for ILEA. The purpose of this study was to investigate vGRF loading in ILEA runners using RSPs across a range of running speeds. Eight ILEA with unilateral transtibial amputations and eight control subjects performed overground running at three speeds (2.5, 3.0, and 3.5m/s). From vGRF, we determined VIP and VALR, which was defined as the change in force divided by the time of the interval between 20 and 80% of the VIP. We observed that VIP and VALR increased in both ILEA and control limbs with an increase in running speed. Further, the VIP and VALR in ILEA intact limbs were significantly greater than ILEA prosthetic limbs and control subject limbs for this range of running speeds. These results suggest that (1) loading variables increase with running speed not only in able-bodied runners, but also in ILEA using RSPs, and (2) the intact limb in ILEA may be exposed to a greater risk of running related injury than the prosthetic limb or able-bodied limbs.

Carbon fiber running-specific prostheses (RSPs) have allowed individuals with lower extremity amputation (ILEA) to participate in running. It has been established that as running speed increases, leg stiffness (Kleg) remains constant while vertical stiffness (Kvert) increases in able-bodied runners. The Kvert further depends on a combination of the torsional stiffnesses of the joints (joint stiffness; Kjoint) and the touchdown joint angles. Thus, an increased understanding of spring-like leg function and stiffness regulation in ILEA runners using RSPs is expected to aid in prosthetic design and rehabilitation strategies. The aim of this study was to investigate stiffness regulation to various overground running speeds in ILEA wearing RSPs. Eight ILEA performed overground running at a range of running speeds. Kleg, Kvert and Kjoint were calculated from kinetic and kinematic data in both the intact and prosthetic limbs. Kleg and Kvert in both the limbs remained constant when running speed increased, while intact limbs in ILEA running with RSPs have a higher Kleg and Kvert than residual limbs. There were no significant differences in Kankle, Kknee and touchdown knee angle between the legs at all running speeds. Hip joints in both the legs did not demonstrate spring-like function; however, distinct impact peaks were observed only in the intact leg hip extension moment at the early stance phase, indicating that differences in Kvert between limbs in ILEA are due to attenuating shock with the hip joint. Therefore, these results suggest that ILEA using RSPs has a different stiffness regulation between the intact and prosthetic limbs during running.

The aim of this study was to test the mechanical advantage (MA) hypothesis, greater involvements of effectors with longer moment arms, in multi-finger torque production tasks in humans. Seventeen right-handed subjects held a customized rectangular handle and produced prescribed torques to the handle, and the forces from all five digits were recorded. There were eight experimental conditions: two prehension types under different sets of mechanical constraints (i.e., fixed-object prehension and free-object prehension) with two torque directions (i.e., supination and pronation) and two torque magnitudes: (i.e., 0.24 and 0.48 Nm). The subjects were asked to produce prescribed torques during the fixed-object prehension or to maintain constant position of the free hand-held object that required the same magnitude and direction of torques as the fixed-object prehension. The index of MA was calculated for agonist and antagonist fingers, which produce torques, respectively, in the same direction and opposite direction to the assigned torques. Agonist fingers showed that the fingers with longer moment arms produced greater grasping forces while antagonist fingers showed that that the fingers with shorter moment arms produced greater grasping forces. These results support the MA hypothesis. The MA index was greater in fixed-object condition as compared to free-object condition. The MA index was greater in pronation condition than supination. We concluded that the central nervous system utilizes the MA of fingers during multi-finger torque production tasks.

Modeling the ankle joint during amputee locomotion is difficult since a definitive joint axis may not exist. Gait analysis estimates joint center positions and defines body segment motions by placing reflective markers on anatomical landmarks. Inverse dynamics techniques then estimate joint kinetics (forces and moments) and mechanical energy expenditure using data from ground reaction forces (GRFs) and the most distal joint (usually the ankle) to make calculations for proximal joints.

Background and Purpose: No reports have analyzed the temporal-spatial, kinematic, or kinetic components of gait coupled with a metabolic analysis of patients with hip disarticulations. Most of the research on this population is based on older adults. As a result, guidelines for reasonable functional outcomes for patients with hip disarticulations who are young, premorbidly fit, and goal oriented are lacking. This report describes quantitative measures of energy cost and gait characteristics of a young soldier with a unilateral traumatic hip disarticulation. Case Description: One patient, a soldier with a unilateral hip disarticulation, was evaluated in the Gait and Motion Analysis Laboratory at 3 months and 38 months postinjury. Outcomes: The patient progressed from use of crutches at 3 months postinjury to independent ambulation at the follow-up visit at 38 months postinjury. At 38 months postinjury, he wore his prosthesis 12 hours per day and achieved step-length symmetry, and his oxygen consumption was 14.49 mL/kg/min at self-selected walking speed. Self-selected walking speed increased from 0.57 m/s at 3 months to 0.86 m/s at 38 months postinjury. During both visits, support time remained greater on the intact limb (72%) than the involved limb (57%), compensatory trunk and pelvic motions were used to advance the prosthetic limb, and the vertical ground reaction force profile was within 2 standard deviations of the data for an uninjured comparison group on the prosthetic side and plateaued on the sound limb. Discussion: Young individuals with traumatic hip disarticulations can achieve and maintain functional independent ambulation with gait deviations. However, metabolic demands may not be as great as previously expected.

Background: Patients with neuropathic conditions may develop plantar bony deformities through neuropathic collapse, frequently placing the skin and soft tissues at risk. Orthoses have been used to accommodate and distribute plantar pressures over a large surface area, thereby minimizing peak loading pressures in small regions and reducing the risk of ulceration. Methods: A previously described bony prominence model (Brodsky et al.) was used to test the pressure-absorbing and force-transmission properties of various orthotic material combinations used in our outpatient clinic. Six materials were tested in five combinations of materials for their compressive properties: [MS]: medium plastazote (M) + soft plastazote (S); [MN]: medium plastazote (M) + nickelplast (N); [NP] nickelplast (N) + Poron (P); [MO] medium plastazote (M) + Spenco (O); and [MC] medium plastazote (M) + P-cell (C). Materials were tested for 100,000 cycles using a materials-testing system (MTS) apparatus (MTS Systems Corporation, Cary, NC) and software. Stress-strain curves comparing the measured peak pressure to the elastic deformation, or the percentage of compression a material experiences with respect to its original thickness, were plotted for each orthotic combination. Results: For MS, MN, MO, and to a lesser extent, MC, a trend was noted for decreased elastic deformation with increased testing. Additionally, the peak pressures before and after testing for each 10,000 testing cycle for each of the orthotic combinations were plotted. For both MN and NP, no demonstrable difference was noted in the peak pressures in the pretesting and post-testing for the 100,000 cycles. The MO showed a trend for increased peak pressures after each testing cycle. Both the MC and MS peak pressures markedly increased with respect to pretesting value. Also, the MN, MO, and MS all showed an overall trend for increased load cell values with increasing cycles at fast loading. Conclusions: These data showed that some orthotic combinations are more effective than others at reducing peak pressures during compression testing using our bony prominence model. Further studies are needed to test the orthotic combinations for shear and combined shear and compression modes.

There is a lack of objective data on acceptable transection levels for transfemoral amputation. We retrospectively correlated the residual limb length of 13 young, athletic transfemoral and knee disarticulation amputees with temporal-spatial, kinematic, and kinetic outcomes after gait analysis. It was hypothesised that shorter residual limb lengths would correlate with greater gait deviations. Patients' residual femoral lengths ranged from 57% to 100% of their intact femoral length. With the exception of one patient, pelvic tilt excursion was inversely related to residual limb length. Limb length did not significantly correlate with any other temporal-spatial, kinematic, or kinetic parameter investigated. Consequently, these results suggest that if the femur is at least 57% of the length of the contralateral femur, length does not dramatically alter gait. This implies that surgeons may have more flexibility to amputate at a higher level to preserve soft tissue quality and improve prosthetic fitting without sacrificing gait function.

The purpose of this experiment was to investigate the effects of frequency and inertia on lower extremity muscle activities during cycling. Electromyographic (EMG) data of seven lower extremity muscles were collected. Sixteen subjects cycled at 250 W across different cadences (60, 80, and 100 rpm) with different loads (0, 0.5, 1.0, 1.5, and 2.0 kg) attached to distal end of their thighs. Load and cadence interactions were observed for the offset of the biceps femoris (BF), the active duration of the rectus femoris (RF), and the peak magnitudes of the vastus lateralis (VL) and the tibialis anterior (TA). Cadence effects were observed in the onset of the gluteus maximus (GM), RF, BF, VL, and TA; the offset of the GM, RF, BF, VL; the duration of the BF and TA; the peak magnitude of the RF and gastrocnemius (GAS); and the crank angle at which the peak magnitude was achieved of the BF, GAS, and soleus (SOL). Load effect was observed from the onset of RF and SOL, the offset of RF, the duration of SOL, and the peak magnitude of BF. These results indicate that inertial properties influence the lower extremity muscular activity in addition to the cadence effect.