Ankle Sprains: Evaluation, Rehabilitation, and Prevention

Pickleball Primer: An Overview of Common Injuries, Treatment, and Optimization Strategies in Pickleball Athlete

Pickleball is one of the fastest growing sports in the United States with millions of players nationwide. It is a relatively appealing sport because of its ease of access, low impact, and highly social atmosphere, allowing players of all ages to participate. As the number of players continues its dramatic increase, player injuries are certain to increase in turn. There is little to no orthopaedic research on pickleball-related injuries and a paucity of data regarding treatment and prevention strategies. This summary was designed to familiarize orthopaedic surgeons with the basics of the sport and highlight potential pickleball-related injuries they may encounter in practice.

Effects of Peroneus Brevis versus Peroneus Longus Muscle Training on Muscle Function in Chronic Ankle Instability: A Randomized Controlled Trial

Chronic ankle instability (CAI) is a common injury that can occur in daily life or sporting events. Injuries to the anterior talofibular, posterior talofibular, and calcaneofibular ligaments are common, and the core of rehabilitation training involves strengthening the peroneus muscle. Many studies on rehabilitation training have focused on strengthening the peroneus brevis muscle, and few studies have focused on specific training to strengthen the peroneus longus muscle. Therefore, this study aims to investigate changes in the symptoms and functions of patients by applying training to strengthen the peroneus longus and peroneus brevis muscles. Home-based training and mobile monitoring were utilized for 12 weeks, divided into peroneus brevis training (PBT) and peroneus longus training (PLT), in 52 adult males with CAI. Participation was voluntary, with enrollment done through a bulletin board, and intervention training allocation was randomly assigned and conducted in a double-blind manner. This study was registered as a trial protocol (KCT 0008478). Foot and ankle outcome scores (FAOS), isokinetic ankle strength tests, and Y-balance tests were performed before and after the intervention. Both PLT and PBT significantly improved in FAOS, inversion, and eversion at angular velocities of 30°/s and 120°/s and in the anterior and posterolateral directions of the Y-balance test (p < 0.05). Interaction effects by time and group were not significant for the FAOS (p > 0.05). However, PLT improved eversion muscle strength and muscle power to a greater degree, compared with PBT, in the anterior and posterolateral directions of the Y-balance test (p < 0.05). In conclusion, both PLT and PBT were effective for CAI patients; in addition, PLT had greater potential for improving strength and balance.

Ankle Sprain and Chronic Lateral Ankle Instability: Optimizing Conservative Treatment

The management protocol for each case of ankle sprain should be individualized and optimized in order to reduce the likelihood of development of chronic instability. Initial treatment aims to address pain, swelling, and inflammation and facilitates regaining pain-free joint motion. Short-term joint immobilization is indicated in severe cases. Subsequently, muscle strengthening, balance training, and targeted activities to develop proprioception are added. Gradually, sports-related activities are added with the ultimate goal of bringing the individual back to preinjury level of activity. This protocol of conservative treatment should always be offered before considering any surgical intervention.

Validation and Application of a Spanish Version of the ALR-RSI Scale (Ankle Ligament Reconstruction-Return to Sport after Injury) in an Active Non-Athlete Population

The most recent scale to quantify psychological readiness before returning to sport is the ALR-RSI (Ankle Ligament Reconstruction-Return to Sport after Injury) scale. The aim of this study was the cross-cultural adaptation to Spanish and application of the ALR-RSI scale in a sample of active people who were not professional athletes, and to carry out an initial psychometric analysis of the functioning of the instrument in this sample. The sample consisted of 257 participants (161 men and 96 women) aged between 18 and 50 years. The adequacy of the model obtained in the exploratory study was confirmed, obtaining a model composed of one factor and 12 indicators in total. The estimated parameters were statistically significant (p < 0.05), and the factor loadings presented values higher than 0.5; thus, all indicators revealed a satisfactory saturation in the latent variable (convergent validity). Regarding internal consistency, the Cronbach's alpha value was 0.886 (excellent internal consistency). This study demonstrated that the ALR-RSI in Spanish is a valid and reproducible scale for evaluating psychological readiness to return to non-professional physical activity after ankle ligament reconstruction in the Spanish population.

Current Concept Review: State of Acute Lateral Ankle Injury Classification Systems

Acute lateral ankle sprain (ALAS) is one of the most frequent musculoskeletal injuries, with a great impact on health and socioeconomic factors. There are few consensuses on this subject and multiple therapeutic options that are difficult to compare due to the lack of a universally adopted classification system. The objective of this study is to is to report the actual knowledge on how ALAS are classified and reported and not to make any therapeutic recommendation. A comprehensive literature review of the literature was carried out through a search in the MEDLINE, Cochrane Library and Google Scholar databases, with identification of articles that describe ways to classify lateral ankle sprains or with relevant content for their classification. Twenty-five different classification systems were identified. The majority of articles referring to ALAS use an unspecific classification. Most classification systems divide sprains into 3 degrees. The most used parameters are the anatomy of the injury, clinical parameters, functional loss and the presence of instability. No articles were found to verify the validity of the systems used, namely regarding their association with therapeutic proposals or prognostic predictions. Based on the available evidence, recommendations cannot be made regarding the most appropriate classification system. The considerable heterogeneity of the existing literature makes it difficult to compare studies and to optimize the treatment and follow-up of these injuries. Future research in this area is necessary to define a practical and rigorous system that can be used universally.

Functional results of modified Mason-Allen suture versus horizontal mattress suture in the arthroscopic Broström-Gould procedure for chronic ankle instability

Background

The arthroscopic Broström–Gould procedure (ABG) gained particular attention among clinicians and researchers due to its high rate of satisfactory results. There is a lack of evidence regarding the differences in clinical outcomes for the various suture techniques. The purpose of this study was to compare the differences in clinical effect in patients treated with one-anchor modified Mason–Allen suture or two-anchor horizontal mattress suture for chronic ankle instability (CAI).

Methods

This retrospective cohort study examined CAI patients who underwent either one-anchor modified Mason–Allen suture or two-anchor horizontal mattress suture ABG between January 2018 and January 2020. Patients were divided into two groups based on the suture knot type used and the associated number of anchors. The operative time, surgical cost, Visual Analog Scale (VAS), American Orthopedic Foot & Ankle Society (AOFAS) Score, Karlsson Ankle Functional Score (KAFS), the rate of return to sports, complications, and measured biomechanical strength using standardized equipment were compared between groups.

Results

Sixty-four CAI patients were included (one-anchor modified Mason–Allen suture group n = 30, two-anchor horizontal mattress suture group n = 34). Compared to the two-anchor horizontal mattress suture group, the one-anchor modified Mason–Allen suture group had significantly shorter operative time (p < .001) and lower surgical cost (p < .001). There were no postoperative complications in the two groups, and no significant differences in the VAS, AOFAS, KAFS, and rate of return to sports in postoperative follow-up between the two groups at 1 and 2 years after surgery. There was no statistically significant difference in biomechanical strength anterior drawer test displacement (p > .05) between the one-anchor modified Mason–Allen suture and two-anchor horizontal mattress suture at 2 years after surgery.

Conclusion

ABG using a one-anchor modified Mason–Allen suture showed comparable clinical results to a two-anchor horizontal mattress suture in the treatment of CAI at intermediate-term follow-up time. However, one-anchor modified Mason–Allen suture may be a faster, simpler, cost-effective substitute technology.

Level of evidence

Level III, comparative study.

Effect of Ligament Mapping from Different Magnetic Resonance Image Quality on Joint Stability in a Personalized Dynamic Model of the Human Ankle Complex

Background. Mechanical models of the human ankle complex are used to study the stabilizing role of ligaments. Identification of ligament function may be improved via image-based personalized approach. The aim of this study is to compare the effect of the ligament origin and insertion site definitions obtained with different magnetic resonance imaging (MRI) modalities on the mechanical behaviour of a dynamic model of the ankle complex. Methods. MRI scans, both via 1.5 T and 3.0 T, were performed on a lower-limb specimen, free from anatomical defects, to obtain morphological information on ligament-to-bone attachment sites. This specimen was used previously to develop the dynamic model. A third ligament attachment site mapping scheme was based on anatomical dissection of the scanned specimen. Following morphological comparison of the ligament attachment sites, their effect on the mechanical behaviour of the ankle complex, expressed by three-dimensional load–displacement properties, was assessed through the model. Results. Large differences were observed in the subtalar ligament attachment sites between those obtained through the two MRI scanning modalities. The 3.0 T MRI mapping was more consistent with dissection than the 1.5 T MRI. Load–displacement curves showed similar mechanical behaviours between the three mappings in the frontal plane, but those obtained from the 3.0 T MRI mapping were closer to those obtained from dissection. Conclusions. The state-of-the-art 3.0 T MRI image analysis resulted in more realistic mapping of ligament fibre origin and insertion site definitions; corresponding load–displacement predictions from a subject-specific model of the ankle complex showed a mechanical behaviour more similar to that using direct ligament attachment observations.

Cross-cultural adaptation and validation of the Arabic version of the foot function index in patients with chronic lateral ankle instability

Background

The English version of the Foot Function Index (FFI) is a reliable and valid tool for measuring pain and functional instability due to chronic lateral ankle instability (CLAI). However, its use among Arabic speakers with CLAI is limited because of the unavailability of the Arabic version of the FFI (FFI-Arb). This study aimed to translate, cross-culturally adapt and validate the FFI from the original English version into Arabic.

Methods

The FFI questionnaire was translated using the Beaton guidelines. Two-hundred-and-thirty native Arabic-speaking participants with CLAI were recruited from different physiotherapy clinics in Saudi Arabia. The convergent validity of the FFI-Arb was tested using the Spearman correlation with the Arabic version Cumberland ankle instability tool (CAIT-Arab). Test-retest reliability was tested among 92 participants who completed the form again after seven days.

Results

Two-hundred-and-thirty participants were enrolled (mean age = 32.09, Standard deviation (SD) = 8.64 years old). There was excellent internal consistency for the three subscales of FFI: pain (0.95), disability (0.97), and activity limitation (0.86), as for the total score (0.98). Convergent validity was analyzed by Spearman rank correlation between the new translated versions of FFI-Arb and CAIT-Arab. The total FFI-Arb and CAIT-Arab scores were moderately correlated (rho = − 0.569; p < 0.001). Subscales of FFI-Arb, such as pain, disability, and activity limitation, were also moderately correlated with CAIT-Arab (rho = − 0.565, rho = − 0.561, rho = − 0.512; p < 0.001). The construct validity was confirmed by principal component analysis (factor analysis) showing a three-factor structure (eigenvalue 1) of FFI-Arb with a total variance of 77.3%. Test-retest reliability was excellent for the total score of the FFI-Arb and all its subscales (interclass correlation coefficient = 0.984–0.999).

Conclusions

The FFI-Arb is a reliable and valid tool for Arabic-speaking patients with CLAI. The FFI-Arb can be utilized in hospitals and clinics in Arabic speaking countries.

Effects of Mobile-Based Rehabilitation in Adolescent Football Players with Recurrent Lateral Ankle Sprains during the COVID-19 Pandemic

Football is a sport involving dynamic movements, and ankle sprains are common sports injuries experienced by football players. Ankle sprains exhibit a high recurrence rate, and rehabilitation training is effective; however, expert-supervised rehabilitation (SVR) at training centers is difficult due to the recent COVID-19 pandemic. This study investigated the effects of mobile-based rehabilitation (MBR) performed at home by high school football players. Sixty players (SVR: 30 and MBR: 30) with recurrent ankle sprains were analyzed. The rehabilitation program consisted of strength and balance training, and the training intensity was gradually increased from week 1 to week 8. The SVR group underwent training at the center with experts, and the BMR group were provided with programs and feedback using mobile devices. Ankle muscle strength was evaluated by measuring isometric eversion, inversion, plantarflexion, and dorsiflexion contraction using a hand-held dynamometer, and dynamic balance was assessed using the Y-balance test (YBT; anterior, posteromedial, and posterolateral); the Foot and Ankle Outcome Score (FAOS) was used for the subjective evaluation. Measurements were conducted at weeks 1, 4, and 8. The patients visited the clinic within 1 week after the injury, and the first test was conducted after consent to participate in the research. Patients underwent the second test at an average of 3.2 weeks after the first test, and the last test at an average of 4.4 weeks after the second test. Although only the SVR group exhibited improvement in strength (eversion and dorsiflexion), YBT and subjective satisfaction at week 4, these measurements improved in both the SVR and MBR groups at week 8. Therefore, mobile–based rehabilitation could be a suitable alternative for high school athletes with ankle sprains who cannot undergo supervised rehabilitation.

Control Design for CABLEankle, a Cable Driven Manipulator for Ankle Motion Assistance

A control design is presented for a cable driven parallel manipulator for performing a controlled motion assistance of a human ankle. Requirements are discussed for a portable, comfortable, and light-weight solution of a wearable device with an overall design with low-cost features and user-oriented operation. The control system utilizes various operational and monitoring sensors to drive the system and also obtain continuous feedback during motion to ensure an effective recovery. This control system for CABLEankle device is designed for both active and passive rehabilitation to facilitate the improvement in both joint mobility and surrounding muscle strength.

Are you sure that ankle is just sprained? A review of common ankle conditions, diagnoses and treatment

PURPOSE OF REVIEW

Acute ankle sprains frequently occur in active children and adolescents but may be the initial clinical presentation of other less common disorders affecting the lower extremities. There are many conditions that may cause one or multiple episodes of ankle injury that are misdiagnosed as an acute ankle sprain. This manuscript highlights diagnoses that should be considered when evaluating and managing a child or adolescent who presents initially and/or repeatedly with an acute ankle sprain.

RECENT FINDINGS

In recent years, various studies have continued to note the prevalence of misdiagnosed ankle sprains, especially amongst the paediatric population. If ankle radiographs demonstrate no abnormalities during an initial clinical examination, often the patient is diagnosed with an acute ankle sprain. However, this can be a misdiagnosis, especially when the patient has had recurrent episodes of ankle injury and ancillary studies are not performed.

SUMMARY

There are many diagnoses that can go unnoticed in the initial evaluation of a paediatric or adolescent ankle sprain. It is important for physicians to be aware of these other conditions to ensure proper treatment plans. This manuscript will analyse five conditions that may be misdiagnosed as an ankle sprain, including juvenile idiopathic arthritis, osteochondritis dissecans of the talus, hereditary sensory motor neuropathy (Charcot-Marie Tooth disease), tarsal coalition and transitional ankle fractures.

Magnetic Resonance Accuracy in the Diagnosis of Anterior Talo-Fibular Ligament Acute Injury: A Systematic Review and Meta-Analysis

BACKGROUND

The studies about injury to the anterior talo-fibular ligament (ATFL) are focused mainly on chronic symptoms and chronic instability, and the literature about the accuracy of magnetic resonance imaging (MRI) in acute injuries is quite lacking.

METHODS

This systematic review with meta-analysis analyzes the diagnostic accuracy of MRI on acute ATFL injury. Relative studies were retrieved after searching three databases (MEDLINE, SCOPUS, and Cochrane Central Register of Controlled Trails). Eligible studies were summarized. The quality of the included articles was assessed using the revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Data were extracted to calculate pooled sensitivity and specificity of MRI.

RESULTS

Seven studies met our inclusion and exclusion criteria. For MRI, the pooled sensitivities and specificity in diagnosing acute ATFL injury were respectively 1.0 (95% CI: 0.58-1) and 0.9 (95% CI: 0.79-0.96). Pooled LR+ and LR- were respectively 10.4 (95% CI: 4.6-23) and 0 (95% CI: 0-0.82).

CONCLUSION

This systematic review with meta-analysis investigated the accuracy of imaging for the diagnosis of acute ATFL injury. Our results demonstrated that MRI shows high diagnostic accuracy in the diagnosis of acute ATFL lesions. These results suggest that routine MRI in the case of suspected ATFL acute injury may be clinically useful, although this is not done in clinical practice due probably to high cost.

Early functional treatment or trivialization? - current treatment strategies in lateral ligament injuries of the ankle

Introduction: Ankle injuries are common in daily orthopaedic trauma practice, with a high incidence of lateral ligament complex (lat-lig-com) injuries of the ankle joint (AJ). Primarily, these lat-lig-com injuries heal sufficiently, although there is a risk of developing chronic ankle instability. However, there is a lack of knowledge about the clinical application and routine for rehabilitation strategies so as to prevent chronic instability. This study investigates the current rehabilitation concepts in clinical routine after ligament injuries of the AJ. Methods: Rehabilitation protocols, provided by orthopaedic and trauma surgery institutions in German speaking countries, were analysed in terms of weight-bearing, range of motion (ROM), physiotherapy and choice of orthosis. All protocols for operatively and non-operatively (nop) treated ligament ruptures of the AJ were included. Results: 120 of 213 institutions provided protocols of lat-lig-com injuries of the AJ. Regarding the orthosis, the nop-treatment group mainly used ankle braces; in contrast, the operative group preferred the use of an ankle boot. The operative group recommends 6-12 weeks for duration of orthosis in contrast to only 6 weeks in the nop group. Significant differences prevail in ROM, with free ROM in non-operative treatment from the first day after trauma (p<0.001) in contrast to a careful increase in ROM in the first 6 weeks post-operatively. Conclusion: Early functional treatment is clinical standard in rehabilitation after lat-lig-com injuries of the ankle. Regarding current literature the differences of restrictions in ROM and orthosis treatment after lat-lig-com injuries suggest a trivialization of conservative treatment in the first period after trauma compared to post-operative aftercare.

Effects of TRX Suspension Training on Proprioception and Muscle Strength in Female Athletes with Functional Ankle Instability

Background: Functional ankle instability (FAI) is a common consequence of ankle sprain injury, especially in high-impact sports. Objectives: To investigate the effect of six weeks of suspension training with total resistance exercises (TRX) on proprioception and muscle strength in female athletes with FAI. Methods: Thirty female athletes with FAI (age: 21.9 ± 2.2 years, height: 169.3 ± 4.2 cm, and weight: 59.8 ± 6.1 kg) were randomly assigned to two equally numbered groups: TRX training and controls based on inclusion and exclusion criteria. In the pre-test, the anthropometric variables and also proprioception accuracy and muscle strength of subjects were evaluated by joint angle reset test (JART) and manual muscle testing (MMT) in both dorsiflexion and plantarflexion motions. The training group completed three sessions per week with progressive load for six weeks, and each training session lasted 15 - 20 minutes, whilst control subjects continued with their normal activity without special sport activities. After six weeks of training, all tests performed in the pre-test phase were also performed in the post-test phase. The t-test was used for statistic analysis (α ≤ 0.05). Results: The findings showed that TRX training significantly improved the proprioception accuracy (P ≤ 0.001) and muscle strength (P ≤ 0.001) in the training group rather than the control group. No statistically significant difference was found in any of the tests between pre-test and post-test for the control group (P > 0.05). Conclusions: Six weeks of TRX suspension training had a positive effect on strength and proprioception accuracy in female athletes with FAI.

Hydrotherapy with hydrogen-rich water compared with RICE protocol following acute ankle sprain in professional athletes: a randomized non-inferiority pilot trial

We analysed the effects of an experimental novel protocol of intensive hydrotherapy with hydrogen-rich water (HRW) on injury recovery in athletic men who suffered an acute ankle sprain (AAS) and compared it with a RICE protocol (rest, ice, compression, elevation). Professional athletes (age 23.7 ± 4.0 years; weight 78.6 ± 5.7 kg, height 182.5 ± 4.3 cm; professional experience 5.9 ± 3.9 years) who incurred AAS during a sport-related activity were randomly assigned immediately after the injury to either hydrogen group (n = 9) or a conventional RICE treatment group (n = 9). Hydrogen group received six 30-min ankle baths with HRW throughout the first 24 h post-injury, with hydrotherapy administered every 4 hours during the intervention period. RICE group stood off the injured leg, with ice packs administered for 20 min every 3 hours, with the injured ankle compressed with an elastic bandage for 24 hours and elevated at all possible times above the level of the heart. HRW was equivalent to RICE protocol to reduce ankle swelling (2.1 ± 0.9% vs. 1.6 ± 0.8%; P = 0.26), range of motion (2.4 ± 1.3 cm vs. 2.7 ± 0.8 cm; P = 0.60), and single-leg balance with eyes opened (18.4 ± 8.2 sec vs. 10.7 ± 8.0 sec; P = 0.06) and closed (5.6 ± 8.4 sec vs. 3.9 ± 4.2 sec; P = 0.59). This non-inferiority pilot trial supports the use of HRW as an effective choice in AAS management. However, more studies are needed to corroborate these findings in other soft tissue injuries.

Acute ankle sprain in athletes: Clinical aspects and algorithmic approach

Acute ankle sprain is the most common lower limb injury in athletes and accounts for 16%-40% of all sports-related injuries. It is especially common in basketball, American football, and soccer. The majority of sprains affect the lateral ligaments, particularly the anterior talofibular ligament. Despite its high prevalence, a high proportion of patients experience persistent residual symptoms and injury recurrence. A detailed history and proper physical examination are diagnostic cornerstones. Imaging is not indicated for the majority of ankle sprain cases and should be requested according to the Ottawa ankle rules. Several interventions have been recommended in the management of acute ankle sprains including rest, ice, compression, and elevation, analgesic and anti-inflammatory medications, bracing and immobilization, early weight-bearing and walking aids, foot orthoses, manual therapy, exercise therapy, electrophysical modalities and surgery (only in selected refractory cases). Among these interventions, exercise and bracing have been recommended with a higher level of evidence and should be incorporated in the rehabilitation process. An exercise program should be comprehensive and progressive including the range of motion, stretching, strengthening, neuromuscular, proprioceptive, and sport-specific exercises. Decision-making regarding return to the sport in athletes may be challenging and a sports physician should determine this based on the self-reported variables, manual tests for stability, and functional performance testing. There are some common myths and mistakes in the management of ankle sprains, which all clinicians should be aware of and avoid. These include excessive imaging, unwarranted non-weight-bearing, unjustified immobilization, delay in functional movements, and inadequate rehabilitation. The application of an evidence-based algorithmic approach considering the individual characteristics is helpful and should be recommended.

Efficacy and Safety of Acupuncture Therapy for Patients with Acute Ankle Sprain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

The efficacy of acupuncture for acute ankle sprain (AAS) is controversial. This study aimed to critically assess the efficacy and safety of acupuncture for AAS.

Methods

Parallel-group randomized controlled trials (RCTs) were included regardless of language or publication date. Participants with AAS were included regardless of age, sex, race, nationality, or diagnostic criteria for AAS. Experimental interventions included acupuncture alone or in combination with traditional therapies. Control interventions included no treatment, placebo, or traditional therapies. The primary outcome was the Kofoed ankle score. The secondary outcomes included visual analogue scale, duration of pain, use of painkiller, ankle circumference, effective rate, cure rate, and adverse events. PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang Digital Periodicals, and Chinese Science and Technology Periodicals database were searched to identify potentially eligible studies from inception to September 10, 2020. World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), ClinicalTrials.gov, Chinese Clinical Trial Registry (ChiCTR), and the reference list of eligible RCTs were checked to identify ongoing or unpublished studies. Risk of bias was assessed by the Cochrane Collaboration's tool. Statistical analyses were performed by RevMan 5.3 software. P < 0.05 indicated statistical significance.

Results

Seventeen eligible studies were included for the statistical analysis. There was no statistically significant difference of Kofoed ankle score between acupuncture and Rest, Ice, Compression, and Elevation (RICE) group (P=0.75). However, acupuncture could significantly relieve pain (P=0.02) and increase cure rate (P=0.004) compared with RICE. Moreover, acupuncture plus RICE could also significantly relieve pain (P < 0.00001) and increase cure rate (P=0.01) compared with RICE alone. Acupuncture combined with massage could significantly relieve pain (P=0.04) compared with massage alone. Acupuncture plus Chinese medicine might be more effective for relieving pain (P < 0.00001), reducing the duration of pain (P < 0.00001), and increasing cure rate (P=0.0002) compared with Chinese medicine alone. Two studies reported no adverse reactions. One study reported that a participant suffered from mild drug-related allergic reaction and was healed without treatment.

Conclusions

The findings of the present study suggest that acupuncture may be beneficial for AAS. However, more large-scale and well-designed RCTs are warranted.

Analysis of a Wearable Robotic System for Ankle Rehabilitation

As one of the most commonly injured joints of the human body, the ankle is often subject to sprains or fractures that require motion assistance to recover mobility. Whereas physiotherapists usually perform rehabilitation in one-on-one sessions with patients, several successful robotic rehabilitation solutions have been proposed in the last years. However, their design is usually bulky and requires the patient to sit or stand in a static position. A lightweight wearable device for ankle motion assistance, the CABLEankle, is here proposed for motion ankle exercising in rehabilitation and training. The CABLEankle is based on a cable-driven S-4SPS parallel architecture, which enables motion assistance over the large motion range of the human ankle in a walking gait. The proposed mechanism design is analyzed with kinematic and static models, and the force closure workspace of the mechanism is discussed with analytical results. Finally, the feasibility of the proposed design is investigated through numerical simulations over the ankle motion range as a characterization of the peculiar motion.