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Saffuri E, Izak E, Tal Y, Kodesh E, Epstein Y, Solav D. Walking with unilateral ankle-foot unloading: a comparative biomechanical analysis of three assistive devices. J Neuroeng Rehabil 2024; 21:67. [PMID: 38689255 DOI: 10.1186/s12984-024-01333-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/05/2024] [Indexed: 05/02/2024] Open
Abstract
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.
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Affiliation(s)
- Eshraq Saffuri
- Faculty of Mechanical Engineering, Technion Israel Institute of Technology, Haifa, Israel
| | - Eyal Izak
- School of Public Health, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yinon Tal
- Faculty of Mechanical Engineering, Technion Israel Institute of Technology, Haifa, Israel
| | - Einat Kodesh
- Department of Physical Therapy, University of Haifa, Haifa, Israel
| | - Yoram Epstein
- School of Public Health, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dana Solav
- Faculty of Mechanical Engineering, Technion Israel Institute of Technology, Haifa, Israel.
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Shin W, Nam D, Ahn B, Kim SJ, Lee DY, Kwon S, Kim J. Ankle dorsiflexion assistance of patients with foot drop using a powered ankle-foot orthosis to improve the gait asymmetry. J Neuroeng Rehabil 2023; 20:140. [PMID: 37864265 PMCID: PMC10589991 DOI: 10.1186/s12984-023-01261-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/02/2023] [Indexed: 10/22/2023] Open
Abstract
BACKGROUND Foot drop is a neuromuscular disorder that causes abnormal gait patterns. This study developed a pneumatically powered ankle-foot orthosis (AFO) to improve the gait patterns of patients with foot drop. We hypothesized that providing unilateral ankle dorsiflexion assistance during the swing phase would improve the kinematics and spatiotemporal gait parameters of such patients. Accordingly, this study aims to examine the efficacy of the proposed assistance system using a strategy for joint kinematics and spatiotemporal gait parameters (stride length, swing velocity, and stance phase ratio). The analysis results are expected to provide knowledge for better design and control of AFOs in patients with foot drop. METHOD Ten foot drop patients with hemiparesis (54.8 y ± 14.1 y) were fitted with a custom AFO with an adjustable calf brace and portable air compressor for ankle dorsiflexion assistance in the gait cycle during the swing phase. All subjects walked under two different conditions without extensive practice: (1) barefoot and (2) wearing a powered AFO. Under each condition, the patients walked back and forth on a 9-m track with ten laps of level ground under the supervision of licensed physical therapists. The lower-limb joint and trunk kinematics were acquired using 12 motion-capture cameras. RESULTS We found that kinematic asymmetry decreased in the three lower-limb joints after ankle dorsiflexion assistance during the swing phase. The average ankle-joint angle increased after using the AFO during the entire gait cycle. Similarly, the knee-joint angle showed a slight increase while using the AFO, leading to a significantly decreased standard deviation within patients. Conversely, the hip-joint angle showed no significant improvements with assistance. While several patients exhibited noticeably lower levels of asymmetry, no significant changes were observed in the average asymmetry of the swing velocity difference between the affected and unaffected sides while using the AFO. CONCLUSION We experimentally validated that ankle dorsiflexion assistance during the swing phase temporarily improves gait asymmetry in foot-drop patients. The experimental results also prove the efficacy of the developed AFO for gait assistance in foot-drop patients.
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Affiliation(s)
- Wonseok Shin
- AI·Robotics R&D Group, Korea Institute of Industrial Technology, Ansan, 15588, Republic of Korea
| | - Dongwoo Nam
- AI·Robotics R&D Group, Korea Institute of Industrial Technology, Ansan, 15588, Republic of Korea
- School of Korea Institute of Industry Technology, Robotics and Virtual Engineering, University of Science and Technology, Ansan, 15588, Republic of Korea
| | - Bummo Ahn
- AI·Robotics R&D Group, Korea Institute of Industrial Technology, Ansan, 15588, Republic of Korea
- School of Korea Institute of Industry Technology, Robotics and Virtual Engineering, University of Science and Technology, Ansan, 15588, Republic of Korea
| | - Sangjoon J Kim
- Henry Samueli School of Engineering Department of Mechanical and Aerospace Engineering, University of California, Irvine, 92697, USA
| | - Dong Yeon Lee
- Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Suncheol Kwon
- AI·Robotics R&D Group, Korea Institute of Industrial Technology, Ansan, 15588, Republic of Korea.
| | - Jung Kim
- Department of Mechanical Engineing, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
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Grunst MM, Wiederien RC, Wilken JM. Carbon fiber ankle-foot orthoses in impaired populations: A systematic review. Prosthet Orthot Int 2023; 47:457-465. [PMID: 36779973 DOI: 10.1097/pxr.0000000000000217] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 01/14/2023] [Indexed: 02/14/2023]
Abstract
BACKGROUND Carbon fiber is increasingly being used in ankle-foot orthoses (AFOs). Orthotic devices and carbon fiber-containing devices have been shown to reduce pain and improve function in multiple patient populations. Although the number of publications and interest in carbon fiber AFOs is growing, a systematic evaluation of their effects is lacking. OBJECTIVES To characterize the effects of carbon fiber AFOs in impaired individuals. STUDY DESIGN Qualitative systematic review. METHODS Systematic searches in PubMed, Embase, CINAHL, and Cochrane Library were completed in July 2020. The results were deduplicated, screened, and assessed for quality by independent reviewers. Articles were excluded if they had nonhuman subjects, only healthy subjects, or included active control systems, motors, or other power sources. RESULTS Seventy-eight articles were included in the qualitative synthesis. Most articles were of low to moderate methodological quality. Five commonly used devices were identified: the Intrepid Dynamic Exoskeletal Orthosis, ToeOff, WalkOn, Neuro Swing, and Chignon. The devices have unique designs and are associated with specific populations. The Intrepid Dynamic Exoskeletal Orthosis was used in individuals with lower-limb trauma, the Neuro Swing and ToeOff in individuals with neurological disorders, the Chignon in individuals with hemiplegia and stroke, and the WalkOn in people with hemiplegia and cerebral palsy. Each device produced favorable outcomes in their respective populations of interest, such as increased walking speed, reduced pain, or improved balance. CONCLUSIONS The mechanical characteristics and designs of carbon fiber AFOs improve outcomes in the populations in which they are most studied. Future literature should diligently report patient population, device used, and fitting procedures.
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Affiliation(s)
- Megan M Grunst
- Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, IA, USA
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Waterval NFJ, van der Krogt MM, Veerkamp K, Geijtenbeek T, Harlaar J, Nollet F, Brehm MA. The interaction between muscle pathophysiology, body mass, walking speed and ankle foot orthosis stiffness on walking energy cost: a predictive simulation study. J Neuroeng Rehabil 2023; 20:117. [PMID: 37679784 PMCID: PMC10483766 DOI: 10.1186/s12984-023-01239-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 08/24/2023] [Indexed: 09/09/2023] Open
Abstract
BACKGROUND The stiffness of a dorsal leaf AFO that minimizes walking energy cost in people with plantarflexor weakness varies between individuals. Using predictive simulations, we studied the effects of plantarflexor weakness, passive plantarflexor stiffness, body mass, and walking speed on the optimal AFO stiffness for energy cost reduction. METHODS We employed a planar, nine degrees-of-freedom musculoskeletal model, in which for validation maximal strength of the plantar flexors was reduced by 80%. Walking simulations, driven by minimizing a comprehensive cost function of which energy cost was the main contributor, were generated using a reflex-based controller. Simulations of walking without and with an AFO with stiffnesses between 0.9 and 8.7 Nm/degree were generated. After validation against experimental data of 11 people with plantarflexor weakness using the Root-mean-square error (RMSE), we systematically changed plantarflexor weakness (range 40-90% weakness), passive plantarflexor stiffness (range: 20-200% of normal), body mass (+ 30%) and walking speed (range: 0.8-1.2 m/s) in our baseline model to evaluate their effect on the optimal AFO stiffness for energy cost minimization. RESULTS Our simulations had a RMSE < 2 for all lower limb joint kinetics and kinematics except the knee and hip power for walking without AFO. When systematically varying model parameters, more severe plantarflexor weakness, lower passive plantarflexor stiffness, higher body mass and walking speed increased the optimal AFO stiffness for energy cost minimization, with the largest effects for severity of plantarflexor weakness. CONCLUSIONS Our forward simulations demonstrate that in individuals with bilateral plantarflexor the necessary AFO stiffness for walking energy cost minimization is largely affected by severity of plantarflexor weakness, while variation in walking speed, passive muscle stiffness and body mass influence the optimal stiffness to a lesser extent. That gait deviations without AFO are overestimated may have exaggerated the required support of the AFO to minimize walking energy cost. Future research should focus on improving predictive simulations in order to implement personalized predictions in usual care. Trial Registration Nederlands Trial Register 5170. Registration date: May 7th 2015. http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=5170.
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Affiliation(s)
- N. F. J. Waterval
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, The Netherlands
- Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, The Netherlands
| | - M. M. van der Krogt
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, The Netherlands
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Rehabilitation Medicine, De Boelelaan 1117, Amsterdam, The Netherlands
- Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, The Netherlands
| | - K. Veerkamp
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Rehabilitation Medicine, De Boelelaan 1117, Amsterdam, The Netherlands
- Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, The Netherlands
- School of Health Sciences and Social Work, Griffith University, Gold Coast, Australia
- Griffith Centre of Biomedical and Rehabilitation Engineering (GCORE), Menzies Health Institute Queensland, and Advanced Design and Prototyping Technologies Institute (ADAPT), Griffith University, Gold Coast, Australia
| | - T. Geijtenbeek
- Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands
| | - J. Harlaar
- Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands
- Department of Orthopaedics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - F. Nollet
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, The Netherlands
- Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, The Netherlands
| | - M. A. Brehm
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, The Netherlands
- Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, The Netherlands
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Waterval NFJ, Brehm MA, Veerkamp K, Geijtenbeek T, Harlaar J, Nollet F, van der Krogt MM. Interacting effects of AFO stiffness, neutral angle and footplate stiffness on gait in case of plantarflexor weakness: A predictive simulation study. J Biomech 2023; 157:111730. [PMID: 37480732 DOI: 10.1016/j.jbiomech.2023.111730] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 06/02/2023] [Accepted: 07/14/2023] [Indexed: 07/24/2023]
Abstract
To maximize effects of dorsal leaf ankle foot orthoses (AFOs) on gait in people with bilateral plantarflexor weakness, the AFO properties should be matched to the individual. However, how AFO properties interact regarding their effect on gait function is unknown. We studied the interaction of AFO bending stiffness with neutral angle and footplate stiffness on the effect of bending stiffness on walking energy cost, gait kinematics and kinetics in people with plantarflexor weakness by employing predictive simulations. Our simulation framework consisted of a planar 11 degrees of freedom model, containing 11 muscles activated by a reflex-based neuromuscular controller. The controller was optimized by a comprehensive cost function, predominantly minimizing walking energy cost. The AFO bending and footplate stiffness were modelled as torsional springs around the ankle and metatarsal joint. The neutral angle of the AFO was defined as the angle in the sagittal plane at which the moment of the ankle torsional spring was zero. Simulations without AFO and with AFO for 9 bending stiffnesses (0-14 Nm/degree), 3 neutral angles (0-3-6 degrees dorsiflexion) and 3 footplate stiffnesses (0-0.5-2.0 Nm/degree) were performed. When changing neutral angle towards dorsiflexion, a higher AFO bending stiffness minimized energy cost of walking and normalized joint kinematics and kinetics. Footplate stiffness mainly affected MTP joint kinematics and kinetics, while no systematic and only marginal effects on energy cost were found. In conclusion, the interaction of the AFO bending stiffness and neutral angle in bilateral plantarflexor weakness, suggests that these should both be considered together when matching AFO properties to the individual patient.
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Affiliation(s)
- N F J Waterval
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, the Netherlands.
| | - M A Brehm
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, the Netherlands
| | - K Veerkamp
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Rehabilitation Medicine, Boelelaan 1117, Amsterdam, the Netherlands; Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, the Netherlands; School of Health Sciences and Social Work, Griffith University, Gold Coast, Australia; Griffith Centre of Biomedical & Rehabilitation Engineering (GCORE), Menzies Health Institute Queensland, and Advanced Design and Prototyping Technologies Institute (ADAPT), Griffith University, Gold Coast, Australia
| | - T Geijtenbeek
- Department of Biomechanical Engineering, Delft University of Technology, Delft, the Netherlands
| | - J Harlaar
- Department of Biomechanical Engineering, Delft University of Technology, Delft, the Netherlands; Department of Orthopaedics, Rotterdam, Erasmus Medical Center, the Netherlands
| | - F Nollet
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, the Netherlands
| | - M M van der Krogt
- Amsterdam UMC Location University of Amsterdam, Rehabilitation Medicine, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam UMC Location Vrije Universiteit Amsterdam, Rehabilitation Medicine, Boelelaan 1117, Amsterdam, the Netherlands; Amsterdam Movement Sciences, Rehabilitation and Development, Amsterdam, the Netherlands
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Rogati G, Caravaggi P, Leardini A, Erani P, Fognani R, Saccon G, Boriani L, Baleani M. A novel apparatus to assess the mechanical properties of Ankle-Foot Orthoses: Stiffness analysis of the Codivilla spring. J Biomech 2022; 142:111239. [PMID: 35940017 DOI: 10.1016/j.jbiomech.2022.111239] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/13/2022] [Accepted: 07/29/2022] [Indexed: 10/16/2022]
Abstract
Ankle-Foot Orthoses (AFOs) are the most common devices prescribed to support the ankle and restore a quasi-normal gait pattern in drop-foot patients. AFO stiffness is possibly the main mechanical property affecting foot and ankle biomechanics. A variety of methods to evaluate this property have been reported, however no standard procedure has been validated and widely used. This study is reporting the repeatability of a novel apparatus to measure AFO stiffness in ideal frictionless conditions. The apparatus is based on a servo-hydraulic testing machine and allows to apply a displacement-controlled rotation of the AFO shell, simulating the physiological ankle dorsi/plantarflexion movement. The repeatability of the apparatus in measuring AFO stiffness in dorsiflexion and plantarflexion was assessed intra- and inter-session in a sample of standard polypropylene AFOs of different sizes (Codivilla spring). The repeatability of the apparatus in measuring the AFO stiffness was high. The Intra- and Inter-session Coefficient of Variation ranged between 0.02 ÷ 1.3 % and 1.3 ÷ 5 %, respectively. The Intra Class Correlation Coefficient ranged between 0.999 ÷ 1 intra- and 0.993 ÷ 0.997 inter-session. AFOs stiffness was observed to increase with the AFO size. The setup is easy to replicate and can be implemented with any torsion-controlled servo-hydraulic testing machine and has resulted simple to use and flexible enough to adapt to AFOs with different sizes. The frictionless contacts characterizing the apparatus make it possible to measure the ideal AFO stiffness by excluding the effect of the fixation methods to the leg and help to improve the repeatability of measurements.
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Affiliation(s)
- G Rogati
- Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
| | - P Caravaggi
- Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
| | - A Leardini
- Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
| | - P Erani
- Medical Technology Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
| | - R Fognani
- Medical Technology Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
| | - G Saccon
- Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
| | - L Boriani
- Spine Surgery Unit, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
| | - M Baleani
- Medical Technology Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
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Rogati G, Caravaggi P, Leardini A. Design principles, manufacturing and evaluation techniques of custom dynamic ankle-foot orthoses: a review study. J Foot Ankle Res 2022; 15:38. [PMID: 35585544 PMCID: PMC9118871 DOI: 10.1186/s13047-022-00547-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 05/10/2022] [Indexed: 11/10/2022] Open
Abstract
Ankle-Foot Orthoses (AFO) can be prescribed to allow drop-foot patients to restore a quasi-normal gait pattern. Standard off-the-shelf AFOs are cost-effective solutions to treat most patients with foot and ankle weakness, but these devices have several limitations, especially in terms of comfort. Therefore, custom AFOs are increasingly adopted to address drop-foot when standard solutions are not adequate. While the solid ones are the most common type of AFO, providing full stability and strong resistance to ankle plantarflexion, passive dynamic AFOs (PD-AFOs) represent the ideal solution for patients with less severe ankle weakness. PD-AFOs have a flexible calf shell, which can bend during the stance phase of walking and absorb energy that can be released to support the limb in the push-off phase. The aim of this review is to assess the state-of-the-art and identify the current limitations of PD-AFOs. An extensive literature review was performed in Google Scholar to identify all studies on custom PD-AFOs. Only those papers reporting on custom PD-AFOs were included in the review. Non peer-reviewed papers, abstract shorter than three pages, lecture notes and thesis dissertations were excluded from the analysis. Particular attention was given to the customization principles and the mechanical and functional tests. For each topic, the main results from all relevant papers are reported and summarized herein. There were 75 papers that corresponded to the search criteria. These were grouped according to the following macro-topics: 16 focusing on scanning technologies and geometry acquisition; 14 on customization criteria; 19 on production techniques; 16 on mechanical testing, and 33 on functional testing. According to the present review, design and production of custom PD-AFOs are becoming increasingly feasible due to advancements in 3D scanning techniques and additive manufacturing. In general, custom PD-AFOs were shown to provide better comfort and improved spatio-temporal parameters with respect to standard solutions. However, no customization principle to adapt PD-AFO stiffness to the patient's degree of ankle impairment or mechanical/functional demand has thus far been proposed.
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Affiliation(s)
- Giulia Rogati
- Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
| | - Paolo Caravaggi
- Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
| | - Alberto Leardini
- Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
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Caravaggi P, Zomparelli A, Rogati G, Baleani M, Fognani R, Cevolini F, Fanciullo C, Cinquepalmi A, Lullini G, Berti L, Leardini A. Development of a Novel, Passive-Dynamic, Custom AFO for Drop-Foot Patients: Design Principles, Manufacturing Technique, Mechanical Properties Characterization, and Functional Evaluation. Applied Sciences 2022; 12:4721. [DOI: 10.3390/app12094721] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Ankle foot orthoses (AFOs) are medical devices prescribed to support the foot and ankle of drop-foot patients. Passive-dynamic AFOs (PD-AFOs) are an effective solution for less severe cases. While off-the-shelf PD-AFOs are rather inexpensive, they provide poor anatomical fit and do not account for the required patient-specific biomechanical support. Three-dimensional (3D) scanning and manufacturing technologies allow manufacturing PD-AFOs customized for the patient’s anatomy and functional needs. This paper aimed to report the overall procedure for designing and manufacturing a novel, fiberglass-reinforced polyamide, custom PD-AFO. The feasibility of the proposed procedure was tested in a case study. The methodology can be divided into the following steps: (i) foot and leg scanning, (ii) 3D design, and (iii) additive manufacturing via selective laser sintering. A custom PD-AFO was designed and manufactured for a 67-year-old male drop-foot patient following paraparesis in severe discarthrosis after spine stabilization surgery. AFO mechanical properties were measured via an ad hoc setup based on a servohydraulic testing machine. The functional outcome was assessed via gait analysis in three conditions: shod (no AFO), wearing an off-the-shelf PD-AFO, and wearing the patient-specific PD-AFO. As expected, wearing the PD-AFO resulted in increased ankle dorsiflexion in the swing phase with respect to the shod condition. Sagittal rotations of the hip, knee, and ankle joints were similar across PD-AFO conditions, but the custom PD-AFO resulted in faster walking speed with respect to the off-the-shelf (walking speed: 0.91 m/s versus 0.85 m/s). Additionally, the patient scored the custom PD-AFO as more comfortable (VAS score: 9.7 vs. 7.3). While the present analysis should be extended to a larger cohort of drop-foot patients, the novel PD-AFO seems to offer a valid, custom solution for drop-foot patients not satisfied with standard orthotics.
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