Walking with unilateral ankle-foot unloading: a comparative biomechanical analysis of three assistive devices.

BACKGROUND: Foot and ankle unloading is essential in various clinical contexts, including ulcers, tendon ruptures, and fractures. Choosing the right assistive device is crucial for functionality and recovery. Yet, research on the impact of devices beyond crutches, particularly ankle-foot orthoses (AFOs) designed to unload the ankle and foot, is limited. This study investigates the effects of three types of devices-forearm crutches, knee crutch, and AFO-on biomechanical, metabolic, and subjective parameters during walking with unilateral ankle-foot unloading. METHODS: Twenty healthy participants walked at a self-selected speed in four conditions: unassisted able-bodied gait, and using three unloading devices, namely forearm crutches, iWalk knee crutch, and ZeroG AFO. Comprehensive measurements, including motion capture, force plates, and metabolic system, were used to assess various spatiotemporal, kinematic, kinetic, and metabolic parameters. Additionally, participants provided subjective feedback through questionnaires. The conditions were compared using a within-subject crossover study design with repeated measures ANOVA. RESULTS: Significant differences were found between the three devices and able-bodied gait. Among the devices, ZeroG exhibited significantly faster walking speed and lower metabolic cost. For the weight-bearing leg, ZeroG exhibited the shortest stance phase, lowest braking forces, and hip and knee angles most similar to normal gait. However, ankle plantarflexion after push-off using ZeroG was most different from normal gait. IWalk and crutches caused significantly larger center-of-mass mediolateral and vertical fluctuations, respectively. Participants rated the ZeroG as the most stable, but more participants complained it caused excessive pressure and pain. Crutches were rated with the highest perceived exertion and lowest comfort, whereas no significant differences between ZeroG and iWalk were found for these parameters. CONCLUSIONS: Significant differences among the devices were identified across all measurements, aligning with previous studies for crutches and iWalk. ZeroG demonstrated favorable performance in most aspects, highlighting the potential of AFOs in enhancing gait rehabilitation when unloading is necessary. However, poor comfort and atypical sound-side ankle kinematics were evident with ZeroG. These findings can assist clinicians in making educated decisions about prescribing ankle-foot unloading devices and guide the design of improved devices that overcome the limitations of existing solutions.

Functional, Spiroergometric, and Subjective Comparisons Between Forearm Crutches and Hands-Free Single Crutches in a Crossover Study.

Background: Following below-knee surgery, the optimal medical mobility device remains controversial as adequate nonweightbearing of the operated extremity is critical to ensure successful healing. The use of forearm crutches (FACs) is well established but requires using both upper extremities. The hands-free single orthosis (HFSO) is an alternative that spares the upper extremities. This pilot study compared functional, spiroergometric, and subjective parameters between HFSO and FAC. Methods: Ten healthy (5 females, 5 males) participants were asked to use HFSOs and FACs in a randomized order. Five functional tests were performed: climbing stairs (CS), an L-shaped indoor course (IC), an outdoor course (OC), a 10-meter walk test (10MWT), and a 6-minute walk test (6MWT). Tripping events were counted while performing IC, OC, and 6MWT. Spiroergometric measurements consisted of a 2-step treadmill test with speeds of 1.5 and 2 km/h, each for 3 minutes. Lastly, a VAS questionnaire was completed to collect data regarding comfort, safety, pain, and recommendations. Results: Significant differences between both aids were observed in CS and IC (HFSO: 29.3 seconds; FAC: 26.1 seconds, P < .03; and HFSO: 33.2 seconds, FAC: 18 seconds, P < .001, respectively). The other functional tests showed no significant differences. The trip events were not significantly different between the use of the 2 aids. Spiroergometric tests showed significant differences regarding heart rate (HFSO: 131.1 bpm at 1.5 km/h and 131 bpm at 2 km/h; FAC: 148.1 bpm at 1.5 km/h and 161.8 bpm at 2 km/h) and oxygen consumption (HFSO: 15.4 mL/min/kg at 1.5 km/h and 16 mL/min/kg at 2 km/h; FAC: 18.3 mL/min/kg at 1.5 km/h and 21.9 mL/min/kg at 2 km/h) at both speeds (all P < .01). In addition, significantly different ratings regarding the items comfort, pain, and recommendation were recorded. Both aids were equally rated for safety. Conclusion: HFSOs may be an alternative to FACs, especially in activities that require physical stamina. Further prospective studies in patients with below-knee surgical intervention concerning everyday clinical use would be interesting. Level of Evidence: Level IV pilot-study.

Biomechanical Analysis of the Unaffected Limb While Using a Hands-Free Crutch.

Basic human ambulation relies on a bipedal gait, which has been reported to be directly related to quality of life. However, injuries to the lower limb can cause an inability to walk and require non-weightbearing periods to heal. Among the many ambulatory aids, standard axillary crutches are prescribed. However, due to the disadvantages of having to use both hands, a slow gait, pain, nerve damage, and gait patterns that differ from that of healthy subjects, currently, a new generation of ambulatory aids has emerged. Among such aids, hands-free crutches (HFCs) are of particular interest due to their form factor, which does not require the use of the hands and facilitates a bipedal gait. In this study, we present an assessment of whether any different gait patterns, compared to overground gait, appeared on the unaffected limb during walking with an HFC. The spatiotemporal parameters, plantar force, lower-limb joint angles, and EMG patterns were evaluated. In conclusion, the results from 10 healthy subjects suggest that wearing an HFC causes only slight changes in the biomechanical gait patterns examined in the unaffected limb compared with overground walking without an HFC.

Comparison of Hip and Low Back Loads between Normal Gait, Axillary Crutch Ambulation and Walking with a Hands-free Crutch in a Healthy Population.

BACKGROUND: Instead of using axillary crutches, using a hands-free crutch (HFC) has been associated with higher functional outcome scores. However, hip and back pain have been reported as side effects. PURPOSE/HYPOTHESIS: The purpose of this study was to compare range of motion and joint reaction forces at the hip and low back between HFC walking, normal walking, and standard crutch walking. It was hypothesized that hip joint reaction forces and low back joint reaction forces would be higher with HFC walking compared with normal walking and axillary crutch walking. STUDY DESIGN: Controlled Laboratory Study. METHODS: Using 3D motion analysis and force plates, kinematics and ground reaction forces were measured in 12 healthy subjects during gait, crutch ambulation and HFC walking. Gait speed, hip and trunk range of motion, and hip and low back reaction forces, were compared using repeated-measures ANOVA. RESULTS: Gait speed during HFC ambulation was reduced 33% compared to crutch ambulation (P<0.001) and 44% compared to normal gait (p<0.001). Hip range of motion was reduced during both crutch conditions compared to gait (p<0.001). Trunk range of motion was greatest during HFC walking compared to both gait and crutch ambulation (p<0.001). Peak hip joint reaction force during HFC walking was 11% lower than during gait (p=0.026) and 30% lower than during crutch walking (p<0.001). Peak low back reaction force during HFC walking was 18% higher than during gait (p=0.032) but not different than during crutch walking. CONCLUSION: Hip joint reaction forces during HFC walking did not exceed those during gait or axillary crutch ambulation. However, a reduction in hip motion using the HFC was associated with increases in trunk motion and low-back loading. These could be a cause for reports of low-back pain accompanying HFC usage. LEVEL OF EVIDENCE: Level 3.

Patient Preference and Physical Demand for Hands-Free Single Crutch vs Standard Axillary Crutches in Foot and Ankle Patients.

BACKGROUND: Weightbearing restrictions following foot and ankle surgery require the use of appropriate assistive devices for nonweightbearing ambulation during the recovery period. Selecting an appropriate assistive device that safely optimizes mobility and participation in daily activities is important to patient compliance and satisfaction. The purpose of this study was to compare physiologic demand, perceived exertion, and patient preference between a hands-free single crutch (HFSC) and standard axillary crutches (SACs) in foot and ankle patients. METHODS: Using 44 preoperative orthopedic foot and ankle patients who had a mean age of 32 (19-51) years, a prospective, randomized, crossover study was performed. The sample consisted of 35 males and 9 females. The mean body mass index (BMI) was 26 (19-36), the mean height was 1.7 m, and the mean weight was 82 kg. Patient data and preactivity heart rate were recorded for all patients, who were then randomized to either an HFSC or SACs. Each patient was randomly assigned to the device they would utilize first using a random number generator. They then crossed over to the other device after vitals returned to within 10% of their baseline heart rate. Every subject completed a 6-minute walk test (6MWT) using both assistive devices in a crossover manner. Immediately following each 6MWT, postactivity heart rate, self-selected walking velocity (SSWV), perceived exertion using the OMNI Rating of Perceived Exertion (OMNI-RPE), and perceived dyspnea using the Modified Borg Dyspnea Scale were obtained. After completing both 6MWTs, patients were asked which assistive device they preferred the most. RESULTS: The HFSC was preferred by 86% of patients. Significantly lower dyspnea scores (2.8 vs 5.3; P < .001), fatigue scores (2.4 vs 5.5; P < .001), preactivity and postactivity change in heart rate (28 vs 46 bpm; P < .001), and mean postactivity heart rate (107 vs 122 bpm; P < .001) were found using the HFSC compared with the SACs. The SAC group trended toward a higher SSWV (0.8 vs 0.77 m/s; P = .08). Those with a BMI greater than 25 also preferred iWALK over SACs (P < .05). Neither group had any falls. Sixty-eight percent of patients complained of axillary/hand pain with the SACs, while 7% complained of proximal leg strap discomfort with the HFSC. CONCLUSION: The results of the current study in our relatively healthy cohort found that foot and ankle patients who were nonweightbearing preferred the HFSC over SACs. They experienced less physiologic demand as well as discomfort and perceived less exertion when using the HFSC compared with SACs. LEVEL OF EVIDENCE: Level II, prospective comparative study.