Prosthetic feet are designed to store energy during early stance and then release a portion of that energy during late stance. The usefulness of providing more energy return depends on whether or not that energy transfers up the lower limb to aid in whole body propulsion. This research examined how increasing prosthetic foot energy return affected walking mechanics across various slopes. Five people with a uni-lateral transtibial amputation walked on an instrumented treadmill at 1.1 m/s for three conditions (level ground, +7.5°, −7.5°) while wearing a prosthetic foot with a novel linkage system and a traditional energy storage and return foot. The novel foot demonstrated greater range of motion (p = 0.0012), and returned more energy (p = 0.023) compared to the traditional foot. The increased energy correlated with an increase in center of mass (CoM) energy change during propulsion from the prosthetic limb (p = 0.012), and the increased prosthetic limb propulsion correlated to a decrease in CoM energy change (i.e., collision) on the sound limb (p < 0.001). These data indicate that this novel foot was able to return more energy than a traditional prosthetic foot and that this additional energy was used to increase whole body propulsion.

People with amputations may find cycling advantageous for exercise, transportation and rehabilitation. The reciprocal nature of stationary cycling also makes it a viable model for research in motor control because the body is supported by the saddle allowing the researcher to focus on the cyclic movement of the legs without the confounding variable of balance. The purpose of this article is to provide an overview of the cycling task in intact cyclists and relate this information to understanding the challenges faced by cyclists with transtibial amputations (CTA). Ongoing research into the biomechanics of CTAs will be summarized to expose the differences between intact and CTA cycling mechanics, asymmetries between limbs of CTAs as well as neuromuscular adaptation following amputation. The article will include recommendations for prosthetic design and modification of the bicycle to improve cycling performance for CTA at all experience levels.

Background: Few published reports exist regarding the control of the human/prosthesis interface in persons with unilateral transtibial amputation. Objective: To investigate strategies employed by prosthetic users in controlling the human/prosthesis interface to highlight challenges associated with either the amputation or the design of the prosthesis. Study Design: Randomized controlled trial. Methods: Cycling was used as the locomotor task to allow for better control of task mechanics compared to walking. A group of nine cyclists with intact limbs were compared to eight cyclists with transtibial amputation (CTA) during a simulated cycling time trial. The CTA group pedaled with a stiff and flexible prosthetic foot. Reaction forces between the foot and the pedal were measured using an instrumented pedal system. The force effectiveness (FE) ratio was used as the measure of task performance. The FE ratio is the force component normal to the bicycle crank arm divided by the resultant force for both limbs and is commonly used to analyze pedaling technique. Results: The CTA group was equally as effective at applying forces as the intact group. Conclusions: These data suggest that individuals with lower limb loss are able to compensate for their amputation to utilize a similar pedaling technique for locomotor performance. As global strategies, e.g. force effectiveness, appear similar between groups future research should focus on local strategies, e.g. individual joint kinematics and kinetics.

Background: Increased knee osteoarthritis risk in patients with unilateral lower extremity limb loss is attributed to increased intact limb loading. Modulating powered ankle prosthesis push-off power may be an effective way to modulate intact limb loading. We examined how changes in the parameter settings of a commercial prosthetic ankle affect power delivery during push-off and the resulting collisional work experienced by the intact limb in persons with unilateral lower extremity limb loss. Methods: Five subjects with unilateral transtibial amputation were fitted with a commercially available powered ankle prosthesis (Ottobock Empower). Subjects walked on a treadmill in seven conditions, where ankle power delivery settings were adjusted using methods accessible to clinicians. Kinetics and kinematics data were collected. Results: Standard adjustment of parameter settings within the prosthetic foot did not alter timing of peak prosthesis power or intact limb collisional work but did have a significant effect on the magnitude of positive prosthesis ankle work. Increased prosthesis work did not decrease intact limb collisional work as predicted. Conclusions: Altering the parameter settings on a commercial powered ankle prosthesis affected the magnitude, but not the timing, of power delivered. Increased prosthesis push-off power did not decrease intact limb loading.

Introduction: The adverse influence of chronic pain on function and psychological health in the general population is well understood. However, the relationship between phantom limb pain (PLP) after limb loss with function and psychological health is less clear. The study purpose was to assess the influences of PLP presence and intensity on function and psychosocial health in individuals with lower-limb loss (LLL). Methods: One hundred two individuals with major LLL completed a study-specific questionnaire on the presence and intensity of their PLP. The Patient-Reported Outcomes Measurement Information System —29 questionnaire was also administered. Results: Of 102 participants, 64% reported PLP, with a mean intensity of 4.8 ± 2.3 out of 10. Individuals with vs. without PLP demonstrated significantly greater sleep disturbances (p = 0.03), whereas the differences in function, fatigue, pain interference, depressive symptoms, anxiety, or ability to participate in social roles and activities were not statistically different between groups (p > 0.05). Of note, mean scores for many of the Patient-Reported Outcomes Measurement Information System—29 short forms among the current sample were similar to the mean of the general population, minimizing the potential clinical impact of PLP on these domains. Conclusions: Our findings indicate a lack of meaningful associations between PLP presence or intensity with function, and psychosocial health among individuals with LLL. These findings conflict with previous research suggesting an adverse relationship between PLP, function, and psychosocial health after limb loss.

Bone stress injuries are prevalent among athletes and military recruits and can significantly compromise training schedules. The development of an ankle–foot orthosis to reduce tibial load and enable a faster return to activity will require new device testing methodologies capable of capturing the contribution of muscular force on tibial strain. Thus, an actuated robotic surrogate leg was developed to explore how tibial strain changes with different ankle–foot orthosis conditions. The purpose of this work was to assess the reliability, scalability, and behavior of the surrogate. A dual actuation system consisting of a Bowden cable and a vertical load applied to the femur via a material testing system, replicated the action-reaction of the Achilles-soleus complex. Maximum and minimum principal strain, maximum shear strain, and axial strain were measured by instrumented strain gauges at five locations on the tibia. Strains were highly repeatable across tests but did not consistently match in vivo data when scaled. However, the stiffness of the ankle–foot orthosis strut did not systematically affect tibial load, which is consistent with in vivo findings. Future work will involve improving the scalability of the results to match in vivo data and using the surrogate to inform exoskeletal designs for bone stress injuries.