Peak passive resistive torque at maximum inversion range of motion in subjects with recurrent ankle inversion sprains

A modified "outside-in" Broström-Gould procedure yielding favorable outcomes for the management of chronic lateral ankle instability-a retrospective study with mid-term follow-up

Purpose: There are various surgical interventions available for the management of Chronic lateral ankle instability (CLAI). The Broström-Gould procedure has gained widespread recognition among foot and ankle specialists for its favorable surgical outcomes. However, with advancements in anatomical understanding and medical technology, further enhancements to the effectiveness of the Gould procedure are warranted. This study introduces a all-inside modified "outside-in" Broström -Gould procedure as an alternative approach for addressing lateral ankle instability. Methods: From August 2020 to October 2022, 40 patients with lateral ankle instability who underwent arthroscopic repair of the modified "outside-in" Broström-Gould procedure were retrospectively analyzed. All patients received standard non-surgical treatment before surgery for more than 6 months without symptom relief. Visual Analogue Scale (VAS) and American Orthopaedic Foot and Ankle Society (AOFAS) and Karlsson-Peterson score were used to evaluate the postoperative effect. Results: All patients were followed up for (14.62 ± 2.04) months. One year after operation, all patients could walk normally, ankle instability sensation disappeared, varus stress test and anterior drawer test were negative. The VAS , AOFAS and Karlsson-Peterson scores of all patients were significantly better compared with those before operation, and the difference between before and after operation was statistically significant. Conclusions: The modified "outside-in" Broström-Gould procedure can effectively treat CLAI, which can obtain satisfactory results. The procedure is straightforward, the impact is minimal, and the aesthetics are pleasing.

Can Arthrogenic Muscle Inhibition Exist in Peroneal Muscles Among People with Chronic Ankle Instability? A Cross-sectional Study

BACKGROUND

Ankle sprains lead to an unexplained reduction of ankle eversion strength, and arthrogenic muscle inhibition (AMI) in peroneal muscles is considered one of the underlying causes. This study aimed to observe the presence of AMI in peroneal muscles among people with chronic ankle instability (CAI).

METHODS

Sixty-three people with CAI and another sixty-three without CAI conducted maximal voluntary isometric contraction (MVIC) and superimposed burst (SIB) tests during ankle eversion, then fifteen people with CAI and fifteen without CAI were randomly invited to repeat the same tests to calculate the test-retest reliability. Electrical stimulation was applied to the peroneal muscles while the participants were performing MVIC, and the central activation ratio (CAR) was obtained by dividing MVIC torque by the sum of MVIC and SIB torques, representing the degree of AMI.

RESULTS

The intra-class correlation coefficients were 0.77 (0.45-0.92) and 0.92 (0.79-0.97) for the affected and unaffected limbs among people with CAI, and 0.97 (0.91-0.99) and 0.93 (0.82-0.97) for the controlled affected and unaffected limbs among people without CAI; Significant group × limb interaction was detected in the peroneal CAR (p = 0.008). The CARs were lower among people with CAI in the affected and unaffected limbs, compared with those without CAI (affected limb = 82.54 ± 9.46%, controlled affected limb = 94.64 ± 6.37%, p < 0.001; unaffected limb = 89.21 ± 8.04%, controlled unaffected limb = 94.93 ± 6.01%, p = 0.016). The CARs in the affected limbs were lower than those in the unaffected limbs among people with CAI (p = 0.023). No differences between limbs were found for CAR in the people without CAI (p = 0.10).

CONCLUSIONS

Bilateral AMI of peroneal muscles is observed among people with CAI. Their affected limbs have higher levels of AMI than the unaffected limbs.

Frontal plane ankle stiffness increases with axial load independent of muscle activity

Ankle sprains are the most common musculoskeletal injury, typically resulting from excessive inversion of the ankle. One way to prevent excessive inversion and maintain ankle stability is to generate a stiffness that is sufficient to resist externally imposed rotations. Frontal-plane ankle stiffness increases as participants place more weight on their ankle, but whether this effect is due to muscle activation or axial loading of the ankle is unknown. Identifying whether and to what extent axial loading affects ankle stiffness is important in understanding what role the passive mechanics of the ankle joint play in maintaining its stability. The objective of this study was to determine the effect of passive axial load on frontal-plane ankle stiffness. We had subjects seated in a chair as an axial load was applied to the ankle ranging from 10% to 50% body weight. Small rotational perturbations were applied to the ankle in the frontal plane to estimate stiffness. We found a significant, linear, 3-fold increase in ankle stiffness with axial load from the range of 0% body weight to 50% body weight. This increase could not be due to muscle activity as we observed no significant axial-load-dependent change in any of the recorded muscle activations. These results demonstrate that axial loading is a significant contributor to maintaining frontal-plane ankle stability, and that disruptions to the mechanism mediating this sensitivity of stiffness to axial loading may result in pathological cases of ankle instability.

Weight, BMI and stability are risk factors associated with lateral ankle sprains and chronic ankle instability: a meta-analysis

IMPORTANCE

Lateral ankle sprains (LAS) are common in the general population and may lead to chronic ankle instability (CAI). If patients at risk could be identified, they could receive adequate and on-time treatment.

OBJECTIVE

The purpose of the current review was to identify all reported intrinsic factors associated with sustaining a LAS or progressing to CAI after an initial sprain.

EVIDENCE REVIEW

PubMed, Embase, MEDline, Cochrane and PEDro were searched for studies published until July 2019. Articles were selected if they included intrinsic factors related to LAS or CAI, subjects of at least 16 years old, and contained a minimum of 10 patients and 10 controls. Studies were excluded if they concerned reviews or case reports, included patients with previous surgical interventions, concomitant injuries or joint pathology other than ankle instability. Quality of included studies was assessed using the Quality in Prognostic Studies tool and quality of evidence was assessed using the GRADEpro tool. In case outcomes were described by at least three studies, data were pooled and assessed by performing a meta-analysis. Based on the pooled data, either a fixed-effects model or random-effects model was selected to correct for the degree of heterogeneity.

FINDINGS

The search resulted in a total of 4154 studies. After title and abstract screening and subsequent full-text screening, 80 relevant studies were included. Results of the meta-analyses indicated that, compared with healthy controls, patients with LAS had a higher mean body mass index (BMI). In patients with CAI, a higher weight and a longer time to stabilise after performing a task (eg, jumping) were found compared with healthy controls. Other outcomes could not be compared using a meta-analysis due to heterogeneity in outcome measurement and the great number of different outcomes reported. Identification of the risk factors when patients present themselves after a LAS may help to determine which patients are at risk of recurrent sprains or developing CAI.

CONCLUSIONS AND RELEVANCE

Based on the findings in this review, a higher BMI, and a higher weight and neuromuscular stability deficits may be regarded risk factors for sustaining a LAS or developing CAI, respectively.

LEVEL OF EVIDENCE

III.

Effects of Walkbot gait training on kinematics, kinetics, and clinical gait function in paraplegia and quadriplegia

BACKGROUND

The robotic-assisted gait training (RAGT) system has gained recognition as an innovative, effective paradigm to improve functional ambulation and activities of daily living in spinal cord injury and stroke. However, the effects of the Walkbot robotic-assisted gait training system with a specialized hip-knee-ankle actuator have never been examined in the paraplegia and quadriplegia population.

OBJECTIVE

The aim of this study was to determine the long-term effects of Walkbot training on clinical for hips and knee stiffness in individuals with paraplegia or quadriplegia.

METHODS

Nine adults with subacute or chronic paraplegia resulting from spinal cord injury or quadriplegia resulting from cerebral vascular accident (CVA) and/or hypoxia underwent progressive conventional gait retraining combined with the Walkbot RAGT for 5 days/week over an average of 43 sessions for 8 weeks. Clinical outcomes were measured with the Functional Ambulation Category (FAC), Modified Rankin Scale (MRS), Korean version of the Modified Barthel Index (K-MBI), Modified Ashworth Scale (MAS). Kinetic and kinematic data were collected via a built-in Walkbot program.

RESULTS

Wilcoxon signed-rank tests showed significant positive intervention effects on K-MBI, maximal hip flexion and extension, maximal knee flexion, active torque in the knee joint, resistive torque, and stiffness in the hip joint (P <  0.05). These findings suggest that the Walkbot RAGT was effective for improving knee and hip kinematics and the active knee joint moment while decreasing hip resistive force. These improvements were associated with functional recovery in gait, balance, mobility and daily activities.

CONCLUSIONS

These findings suggest that the Walkbot RAGT was effective for improving knee and hip kinematics and the active knee joint moment while decreasing hip resistive force. This is the first clinical evidence for intensive, long-term effects of the Walkbot RAGT on active or resistive moments and stiffness associated with spasticity and functional mobility in individuals with subacute or chronic paraplegia or quadriplegia who had reached a plateau in motor recovery after conventional therapy.

The efficacy of virtual reality assisted versus traditional rehabilitation intervention on individuals with functional ankle instability: a pilot randomized controlled trial

PURPOSE

Virtual reality (VR) training, a virtual environment commonly generated by computer systems, may enhance the therapeutic efficacy of functional rehabilitation programmes. The aim of this study was to investigate the efficacy of a VR assisted intervention (VRAI) versus traditional rehabilitation intervention (TRI) on functional ankle instability (FAI).

METHODS

A single-blind randomized controlled study was conducted with 10 subjects for each group. The VRAI was conducted with the Nintendo Wii Fit Plus, whilst the TRI was conducted with a series of exercises with theraband. The muscle strength change of the two groups and the difference between pre and post interventions for each group were compared.

RESULTS

The VRAI group had less improvement in the muscle strength of all ankle motions than did the TRI group (p > .05). The VRAI group had a greater improvement in muscle strength of plantar flexion than other motions, whilst the TRI group had an improvement in muscle strength of all ankle motions (p < .05).

CONCLUSIONS

The effects of VR training for the condition of FAI were not comparable to conventional training. However, VR training may be added to the conventional training programme as an optional for the condition of FAI. Implications for Rehabilitation Functional ankle instability (FAI) is subjective feelings of ankle instability resulting from proprioceptive and neuromuscular deficits in which individuals may experience "giving way" condition of the ankle. Therapeutic applications of virtual reality (VR) may be comparable to traditional rehabilitation interventions (TRI) in the rehabilitation of individuals with FAI. However, there is no definitive evidence for the issue. Integrating low-cost VR into functional rehabilitation programme can provide insight into an issue of whether it can be replaced with traditional therapeutic approaches. Although, the efficacy of VR application on strengthening muscles is unable to compare to traditional strengthening programmes, it may be considered an optional treatment based on the proprioceptive improvements.

Four Weeks of Balance Training does not Affect Ankle Joint Stiffness in Subjects with Unilateral Chronic Ankle Instability

Background

Balance training has been shown to be effective in preventing ankle sprain recurrences in subjects with chronic ankle instability (CAI) but the biomechanical pathways underlying the clinical outcomes are still unknown. This study was conducted to determine if a 4-week balance training intervention can alter the mechanical characteristics in ankles with CAI.

Methods

Twenty-two recreationally active subjects with unilateral CAI were randomized to either a control (n = 11, 35.1 ± 9.3 years) or intervention (n = 11, 33.5 ± 6.6 years) group. Subjects in the intervention group were trained on the affected limb with static and dynamic components using a Biodex balance stability system for 4-weeks. The ankle joint stiffness and neutral zone in inversion and eversion directions on the involved and uninvolved limbs was measured at baseline and post-intervention using a dynamometer.

Results

At baseline, the mean values of the inversion stiffness (0.69 ± 0.37 Nm/degree) in the involved ankle was significantly lower (p < 0.011, 95% CI [0.563, 0.544]) than that of uninvolved contralateral ankle (0.99 ± 0.41 Nm/degree). With the available sample size, the eversion stiffness, inversion neutral zone, and eversion neutral zone were not found to be significantly different between the involved and uninvolved contralateral ankles. The 4-week balance training intervention failed to show any significant effect on the passive ankle stiffness and neutral zones in inversion and eversion.

Conclusion

Decreased inversion stiffness in the involved chronic unstable ankle was found that of uninvolved contralateral ankle. The 4-week balance training program intervention was ineffective in altering the mechanical characteristics of ankles with CAI.

Level of evidence

Randomized controlled clinical trial; Level of evidence, 1.

A Robot-Driven Computational Model for Estimating Passive Ankle Torque With Subject-Specific Adaptation

BACKGROUND

Robot-assisted ankle assessment could potentially be conducted using sensor-based and model-based methods. Existing ankle rehabilitation robots usually use torquemeters and multiaxis load cells for measuring joint dynamics. These measurements are accurate, but the contribution as a result of muscles and ligaments is not taken into account. Some computational ankle models have been developed to evaluate ligament strain and joint torque. These models do not include muscles and, thus, are not suitable for an overall ankle assessment in robot-assisted therapy.

METHODS

This study proposed a computational ankle model for use in robot-assisted therapy with three rotational degrees of freedom, 12 muscles, and seven ligaments. This model is driven by robotics, uses three independent position variables as inputs, and outputs an overall ankle assessment. Subject-specific adaptations by geometric and strength scaling were also made to allow for a universal model.

RESULTS

This model was evaluated using published results and experimental data from 11 participants. Results show a high accuracy in the evaluation of ligament neutral length and passive joint torque. The subject-specific adaptation performance is high, with each normalized root-mean-square deviation value less than 10%.

CONCLUSION

This model could be used for ankle assessment, especially in evaluating passive ankle torque, for a specific individual. The characteristic that is unique to this model is the use of three independent position variables that can be measured in real time as inputs, which makes it advantageous over other models when combined with robot-assisted therapy.

Mechanosensitivity of the median nerve in patients with chronic carpal tunnel syndrome

The aim was to investigate the relationship between the effects of median nerve strain during the elbow extension component of the upper limb neurodynamic test 1 (ULNT1) and the evoked musculoskeletal changes. 11 patients with chronic carpal tunnel syndrome (CTS) and 11 matched asymptomatic controls participated in the study. In all subjects, elbow extension was carried out in both ULNT1 and neutral positions of the shoulder and arm. From these two starting positions a KIN-COM(®) dynamometer carried out passive elbow extension while EMG activity of 10 arm and shoulder muscles, elbow-flexor resistive torque and elbow extension ROM were measured concurrently. The result showed that, in the ULNT1 position, increased EMG activity of the involved muscles, increased elbow extension resistive torque and pain responses occurred much earlier in the range of elbow extension in the CTS group compared to healthy controls. These findings demonstrated increased mechanosensitivity of the median nerve in CTS patients compared to healthy controls.

A mechanical jig for measuring ankle supination and pronation torque in vitro and in vivo

This study presents the design of a mechanical jig for evaluating the ankle joint torque on both cadaver and human ankles. Previous study showed that ankle sprain motion was a combination of plantarflexion and inversion. The device allows measurement of ankle supination and pronation torque with one simple axis in a single step motion. More importantly, the ankle orientation allows rotation starting from an anatomical position. Six cadaveric specimens and six human subjects were tested with simulated and voluntary rotation respectively. The presented mechanical jig makes possible the determination of supination torque for studying ankle sprain injury and the estimation of pronation torque for examining peroneal muscle response.

Avaliação do torque de resistência passiva em atletas femininas com entorse de tornozelo

INTRODUÇÃO: A entorse de tornozelo é uma das lesões mais comuns em atletas. Uma forma de avaliar a frouxidão ligamentar pode ser através da medida da amplitude passiva dos movimentos de inversão e eversão do pé para estimar a resistência passiva das estruturas capsuloligamentares do tornozelo, o qual pode ser chamado de torque de resistência passiva. Existem poucos estudos que utilizam a avaliação do torque passivo do tornozelo para avaliar a resistência da cápsula e dos ligamentos. OBJETIVO: O objetivo deste estudo foi comparar o torque passivo dos movimentos de inversão e eversão do pé em atletas com e sem história de entorse de tornozelo. MÉTODO: Participaram do estudo 32 atletas de basquetebol e voleibol feminino (16,06 ± 0,8 anos, 67,63 ± 8,17kg, 177,8 ± 6,47cm). Seus tornozelos foram divididos em dois grupos: grupo controle (29), composto por tornozelos sem sintomas, e grupo entorse de tornozelo, composto por tornozelos que sofreram lesão (29). O torque dos movimentos passivos do tornozelo foi registrado por um dinamômetro isocinético, e a atividade dos músculos fibular longo e tibial anterior foi medida por um eletromiógrafo. As atletas realizaram duas repetições do movimento de inversão e eversão, nas velocidades de 5, 10 e 20°/s e, em seguida, o mesmo protocolo foi repetido apenas para o movimento de inversão máxima do pé. RESULTADOS: O torque de resistência passiva durante os movimentos de inversão e eversão do pé foi menor no grupo com entorse do tornozelo. Este grupo também mostrou menor torque durante o movimento de inversão máxima do pé. Não foram observadas diferenças entre o movimento de inversão e eversão. CONCLUSÕES: A entorse de tornozelo leva a um menor torque de resistência passiva, indicando redução da resistência dos ligamentos colaterais do tornozelo e uma frouxidão articular mecânica.

Chronic ankle instability: evolution of the model

CONTEXT

The Hertel model of chronic ankle instability (CAI) is commonly used in research but may not be sufficiently comprehensive. Mechanical instability and functional instability are considered part of a continuum, and recurrent sprain occurs when both conditions are present. A modification of the Hertel model is proposed whereby these 3 components can exist independently or in combination.

OBJECTIVE

To examine the fit of data from people with CAI to 2 CAI models and to explore whether the different subgroups display impairments when compared with a control group.

DESIGN

Cross-sectional study.

PATIENTS OR OTHER PARTICIPANTS

Community-dwelling adults and adolescent dancers were recruited: 137 ankles with ankle sprain for objective 1 and 81 with CAI and 43 controls for objective 2.

INTERVENTION(S)

Two balance tasks and time to recover from an inversion perturbation were assessed to determine if the subgroups demonstrated impairments when compared with a control group (objective 2).

MAIN OUTCOME MEASURE(S)

For objective 1 (fit to the 2 models), outcomes were Cumberland Ankle Instability Tool score, anterior drawer test results, and number of sprains. For objective 2, outcomes were 2 balance tasks (number of foot lifts in 30 seconds, ability to balance on the ball of the foot) and time to recover from an inversion perturbation. The Cohen d was calculated to compare each subgroup with the control group.

RESULTS

A total of 56.5% of ankles (n = 61) fit the Hertel model, whereas all ankles (n = 108) fit the proposed model. In the proposed model, 42.6% of ankles were classified as perceived instability, 30.5% as recurrent sprain and perceived instability, and 26.9% as among the remaining groups. All CAI subgroups performed more poorly on the balance and inversion-perturbation tasks than the control group. Subgroups with perceived instability had greater impairment in single-leg stance, whereas participants with recurrent sprain performed more poorly than the other subgroups when balancing on the ball of the foot. Only individuals with hypomobility appeared unimpaired when recovering from an inversion perturbation.

CONCLUSIONS

The new model of CAI is supported by the available data. Perceived instability alone and in combination characterized the majority of participants. Several impairments distinguished the sprain groups from the control group.

Inclusion criteria when investigating insufficiencies in chronic ankle instability

INTRODUCTION

The development of chronic ankle instability (CAI) is the primary residual deficit after ankle joint sprain. It has been proposed that CAI is characterized by two entities, namely, mechanical instability and functional instability. Each of these entities in turn is composed of various insufficiencies. Research of functional insufficiencies to date has shown large variances in results. One particular reason for this could be discrepancies in inclusion criteria and definitions between CAI, mechanical instability, and functional instability used in the literature. Thus, we endeavored to undertake a systematic investigation of those studies published in the area of CAI to identify if there is a large discrepancy in inclusion criteria across studies.

METHODS

A systematic search of the following databases was undertaken to identify relevant studies: Cochrane Central Register of Controlled Trials, PubMed, CINAHL, SportDiscus, PEDro, and AMED.

RESULTS

The results of this study indicate that there is a lack of consensus across studies regarding what actually constitutes ankle instability. Furthermore, it is evident that the majority of studies use very different inclusion criteria, which leads to a nonhomogenous population and to difficulties when comparing results across studies.

CONCLUSIONS

Future studies should endeavor to be specific with regard to the exact inclusion criteria being used. Particular emphasis should be given to issues such as the number of previous ankle sprains reported by each subject and how often and during which activities episodes of "giving way" occur as well as the presence of concomitant symptoms such as pain and weakness. We recommend that authors use one of the validated tools for discriminating the severity of CAI. Furthermore, we have provided a list of operational definitions and key criteria to be specified when reporting on studies with CAI subjects.

Understanding acute ankle ligamentous sprain injury in sports

This paper summarizes the current understanding on acute ankle sprain injury, which is the most common acute sport trauma, accounting for about 14% of all sport-related injuries. Among, 80% are ligamentous sprains caused by explosive inversion or supination. The injury motion often happens at the subtalar joint and tears the anterior talofibular ligament (ATFL) which possesses the lowest ultimate load among the lateral ligaments at the ankle. For extrinsic risk factors to ankle sprain injury, prescribing orthosis decreases the risk while increased exercise intensity in soccer raises the risk. For intrinsic factors, a foot size with increased width, an increased ankle eversion to inversion strength, plantarflexion strength and ratio between dorsiflexion and plantarflexion strength, and limb dominance could increase the ankle sprain injury risk. Players with a previous sprain history, players wearing shoes with air cells, players who do not stretch before exercising, players with inferior single leg balance, and overweight players are 4.9, 4.3, 2.6, 2.4 and 3.9 times more likely to sustain an ankle sprain injury. The aetiology of most ankle sprain injuries is incorrect foot positioning at landing – a medially-deviated vertical ground reaction force causes an explosive supination or inversion moment at the subtalar joint in a short time (about 50 ms). Another aetiology is the delayed reaction time of the peroneal muscles at the lateral aspect of the ankle (60–90 ms). The failure supination or inversion torque is about 41–45 Nm to cause ligamentous rupture in simulated spraining tests on cadaver. A previous case report revealed that the ankle joint reached 48 degrees inversion and 10 degrees internal rotation during an accidental grade I ankle ligamentous sprain injury during a dynamic cutting trial in laboratory. Diagnosis techniques and grading systems vary, but the management of ankle ligamentous sprain injury is mainly conservative. Immobilization should not be used as it results in joint stiffness, muscle atrophy and loss of proprioception. Traditional Chinese medicine such as herbs, massage and acupuncture were well applied in China in managing sports injuries, and was reported to be effective in relieving pain, reducing swelling and edema, and restoring normal ankle function. Finally, the best practice of sports medicine would be to prevent the injury. Different previous approaches, including designing prophylactice devices, introducing functional interventions, as well as change of games rules were highlighted. This paper allows the readers to catch up with the previous researches on ankle sprain injury, and facilitate the future research idea on sport-related ankle sprain injury.

Treatment of common deficits associated with chronic ankle instability

Lateral ankle sprains are amongst the most common injuries incurred by athletes, with the high rate of reoccurrence after initial injury becoming of great concern. Chronic ankle instability (CAI) refers to the development of repetitive ankle sprains and persistent residual symptoms post-injury. Some of the initial symptoms that occur in acute sprains may persist for at least 6 months post-injury in the absence of recurrent sprains, despite the athlete having returned to full functional activity. CAI is generally thought to be caused by mechanical instability (MI) or functional instability (FI), or both. Although previously discussed as separate entities, recent research has demonstrated that deficits associated with both MI and FI may co-exist to result in CAI. For clinicians, the main deficits associated with CAI include deficits in proprioception, neuromuscular control, strength and postural control. Based on the literature reviewed, it does seem that subjects with CAI have a deficit in frontal plane ankle joint positional sense. Subjects with CAI do not appear to exhibit any increased latency in the peroneal muscles in response to an external perturbation. Preliminary data suggest that feed-forward neuromuscular control may be more important than feed-back neuromuscular control and interventions are now required to address deficits in feed-forward neuromuscular control. Balance training protocols have consistently been shown to improve postural stability in subjects with CAI. Subjects with CAI do not experience decreased peroneus longus strength, but instead may experience strength deficits in the ankle joint invertor muscles. These findings are of great clinical significance in terms of understanding the mechanisms and deficits associated with CAI. An appreciation of these is vital to allow clinicians to develop effective prevention and treatment programmes in relation to CAI.

Mudanças no padrão temporal da EMG de músculos do tornozelo e pé pré e pós-aterrissagem em jogadores de voleibol com instabilidade funcional

INTRODUÇÃO: A instabilidade funcional (IF) é a complicação mais comum após o entorse de tornozelo; acomete até 52% dos atletas com história de entorse. O entorse de tornozelo é uma das lesões esportivas mais comuns, inclusive no voleibol, em que 90% dos entorses de tornozelo ocorrem durante a aterrissagem, após o movimento de bloqueio. A IF é definida por queixas de falseios e entorses recorrentes, sem que haja evidências clínicas de lesão ligamentar, sendo extremamente prejudicial para a prática do voleibol, pois interfere na realização dos fundamentos envolvidos na modalidade. OBJETIVOS: Comparar os padrões temporais e de magnitude da atividade eletromiográfica dos músculos tibial anterior (TA), fibular longo (FL) e gastrocnêmio lateral (GL) durante a aterrissagem do salto vertical após a execução da habilidade do bloqueio do voleibol entre jogadores com e sem IF de tornozelo. MÉTODOS: Foi adquirida a atividade EMG do tibial anterior, do fibular longo e do gastrocnêmio lateral em 21 atletas com IF (GI) e em 19 atletas controle (GC) - idade média de 20 ± 4 anos. Os envoltórios lineares foram calculados para cada um dos grupos no período de tempo entre 200ms antes e 200ms após o instante do impacto, determinados por meio da componente vertical da FRS. A magnitude e o instante do pico máximo de cada um dos músculos também foram determinados matematicamente. Os grupos foram comparados por meio do teste t (α = 0,05). RESULTADOS: O grupo com instabilidade apresentou instante de pico do TA mais tardio ± (GC = -107,4 ± 29,6ms; GI = -134,0 ± 26,0ms) e FL (GC = -11,0 ± 55,9ms; GI = -41,7 ± 49,8ms) e menor pico de TA (GC = 68,5 ± 17,2%; GI = 81,2 ± 28,8%) e FL (GC = 72,9 ± 27,3%; GI = 59,1 ± 16,0%), CONCLUSÕES: Os resultados mostram um padrão de alteração mais tardio e com menor magnitude nos músculos de atletas com IF que podem predispô-los à condição de instabilidade, mesmo na ausência de lesão anatômica.

Possible factors related to functional ankle instability

STUDY DESIGN

Case control study.

OBJECTIVES

To classify individuals with functional ankle instability (FAI) into deficit and non-deficit categories based on the evaluation of the most common factors that have been proposed to be related to FAI.

BACKGROUND

Recent studies have suggested that FAI may be secondary to a combination of factors including ankle proprioceptive deficit, muscular weakness, impaired balance, delayed neuromuscular reaction time, and joint laxity. However, only a few authors have investigated the prevalence and association among these factors in a single group of individuals.

METHODS AND MEASURES

The above 5 factors were tested bilaterally in 21 individuals with FAI and in 16 healthy control subjects. Data were analyzed for (1) within- and between-group comparison, (2) classification of subjects with FAI into deficit and no-deficit categories, and (3) magnitude of association between factors in the subjects with FAI using Pearson bivariate correlation.

RESULTS

Balance control and evertors' strength were significantly less on the affected side in comparison to the unaffected side in subjects with FAI. The evertors' strength was also significantly different between the side difference of the FAI group and the side difference of the control group. Passive ankle stiffness was significantly correlated to balance control, ankle proprioception, and evertor peak torque. Individuals with FAI demonstrated a large variation in the deficit categories ranging from multiple deficits to no noticeable deficits.

CONCLUSION

Mechanical alterations in the ankle joint may influence several aspects of the ankle's functional ability. Alterations in the afferent processes, represented in this study by ankle proprioception, may effect the evertors' strength or vice versa. More importantly, individuals with FAI might exhibit high variability in ankle deficits.

Ankle function during hopping in subjects with functional instability of the ankle joint

A common mechanism of inversion injury involves a lateral movement producing a hypersupination of the ankle joint. To date, no study has investigated patterns of muscle activity, three-dimensional (3D) joint kinematics and kinetics simultaneously in a group of subjects with functional instability (FI) compared with a non-injured control group during a lateral hopping test. Twenty-six subjects with the subjective complaint of FI of the ankle joint and 24 non-injured healthy control subjects volunteered to participate in the study. We measured 3D lower limb kinematics, kinetics and surface electromyography (EMG) of the rectus femoris, tibialis anterior, peroneus longus and soleus muscle in all subjects during a lateral hop task for the period 200 ms pre- and post-initial contact (IC). FI subjects were observed to have a less-everted position of the ankle joint during the time period from 45 ms pre-IC to 95 ms post-IC (P<0.05). FI subjects were also found to have an increase in pre- and post-IC rectus femoris, tibialis anterior and solues EMG activity. The results suggest that subjects with FI exhibit changes in ankle joint movement and neuromuscular control that could predispose to further injury.

Hindfoot instability in cavovarus deformity: static and dynamic balancing

BACKGROUND

Chronic lateral ankle instability has been associated with varus deformity of the hindfoot, hyperactivity of the peroneus longus muscle, and insufficiency of the lateral ligaments. Many operative procedures have been described to correct this problem, but instability can recur if all contributing components are not treated. The purpose of this study was to offer an approach in the diagnosis and treatment of recurrent lateral ankle instability.

METHODS

Eight consecutive patients (nine feet) were treated for recurrent chronic lateral ankle instability. The average age at surgery was 25 (range 8 to 37) years. All patients had prior operative procedures that failed and had persistent pain and functional instability of the ankle joint. After clinical and radiographic examination, lateralizing calcaneal osteotomy to correct the structured varus deformity and peroneus longus to peroneus brevis tendon transfer to add dynamic correction were done in all patients. A Broström ligament reconstruction was added in four feet. All patients were evaluated clinically and radiographically at an average followup of 37 months. Preoperatively and postoperatively patients were evaluated by means of the American Orthopaedic Foot and Ankle Society (AOFAS) Score.

RESULTS

All patients were satisfied with the operation. The overall AOFAS-Score improved from 57 points preoperatively to 87 points postoperatively. Hindfoot alignment was restored to a valgus position at final evaluation.

CONCLUSIONS

Recurrent chronic lateral ankle instability often is associated with chronic hindfoot malalignment and leads to functional impairment and patient discomfort. Clinical examination should determine the causes of instability. Varus malalignment of the hindfoot, hyperactivity of the peroneus longus muscle, and insufficiency of the lateral ligaments should be assessed and treated in a combined operative procedure to correct structured, static and dynamic components of the instability. The preliminary results of this particular approach are encouraging.

Lateral ankle sprain: isokinetic test reliability and comparison between invertors and evertors

OBJECTIVE

Evaluate reliability of isokinetic tests for inversion and eversion in individuals with recurrent lateral ankle sprain and compare inversion to eversion muscle performance in the same ankles.

DESIGN

Reliability was evaluated by comparing the results of two ankle inversion/eversion isokinetic tests. Inversion and eversion were compared with the results presented by the tests.

BACKGROUND

Previous studies showed reliable isokinetic tests for ankles with no sprain history. It is unknown if such tests can also be performed in lateral sprained ankles. It is unclear whether there is difference between invertors and evertors in these ankles.

METHODS

Eleven men with recurrent ankle lateral sprain in one limb were tested using an isokinetic dynamometer. The tests consisted of 5 cycles of maximal contraction in 30 degrees /s and 120 degrees /s. Both injured and noninjured ankles were tested. Peak torque was recorded for analysis.

RESULTS

The tests are reliable and intraclass coefficient correlation varied from 0.71 to 0.95. Invertors generated higher peak torques than evertors (P = 0.03) when injured ankles were tested at 120 degrees /s.

CONCLUSIONS

Isokinetic inversion/eversion tests showed to be reliable. A decrease in peak torques can be seen during higher velocity tests. The only difference between invertors and evertors was seen when injured ankles were tested at 120 degrees /s. In this case invertors showed higher peak torques.

Sensorimotor control is impaired in dancers with functional ankle instability

BACKGROUND

Factors potentially causing chronic instability after ankle inversion sprains have rarely been examined during the injuring movement.

PURPOSE

To compare control of ankle movement during quiet stance and after inversion perturbation in chronically unstable ankles (n = 16) with healthy controls (n = 26).

METHODS

Movement control was measured as magnitude of lateral ankle oscillation, using 3SPACE Fastrak during single leg stance (baseline oscillation) in two foot positions, flat and demi-pointe. In both positions, time to resume baseline oscillation after inversion perturbation (perturbation time) of 15 degrees for the flat foot and 7.5 degrees on demi-pointe was also determined.

RESULTS

Baseline oscillation on demi-pointe was significantly smaller (P < 0.005) for the sprained group (2.5 +/- 0.5 mm) than for controls (4.0 +/- 2.3 mm). Perturbation time for the flat foot was significantly longer (P < 0.05) for the sprained group (2.2 +/- 0.4 seconds) than for controls (1.8 +/- 0.5 seconds). However, failure rate was higher (P < 0.05) among the sprained group than controls for perturbation with the foot flat and baseline oscillation on demi-pointe.

CONCLUSIONS

Findings demonstrated altered sensorimotor control in chronically unstable ankles. Those sprainers who successfully completed the tasks minimized oscillation. The impairments in the sprained group may reflect deficits in either movement detection, peroneal muscle response, or both.

Diagnosis and Management of the Painful Ankle/Foot. Part 2: Examination, Interpretation, and Management

Diagnosis, interpretation, and subsequent management of ankle/foot pathology can be challenging to clinicians. A sensitive and specific physical examination is the strategy of choice for diagnosing selected ankle/foot injuries and additional diagnostic procedures, at considerable cost, may not provide additional information for clinical diagnosis and management. Because of a distal location in the sclerotome and the reduced convergence of afferent signals from this region to the dorsal horn of the spinal cord, pain reference patterns are low and the localization of symptoms is trustworthy. Effective management of the painful ankle/foot is closely linked to a tissue-specific clinical examination. The examination of the ankle/foot should include passive and resistive tests that provide information regarding movement limitations and pain provocation. Special tests can augment the findings from the examination, suggesting compromises in the structural and functional integrity of the ankle/foot complex. The weight bearing function of the ankle/foot compounds the clinician's diagnostic picture, as limits and pain provocation are frequently produced only when the patient attempts to function in weight bearing. As a consequence, clinicians should consider this feature by implementing numerous weightbearing components in the diagnosis and management of ankle/foot afflictions. Limits in passive motion can be classified as either capsular or non-capsular patterns. Conversely, patients can present with ankle/foot pain that demonstrates no limitation of motion. Bursitis, tendopathy, compression neuropathy, and instability can produce ankle/foot pain that is challenging to diagnose, especially when they are the consequence of functional weight bearing. Numerous non-surgical measures can be implemented in treating the painful ankle/foot, reserving surgical interventions for those patients who are resistant to conservative care.

The influence of external orthotic support on the adaptive gait characteristics of individuals with chronically unstable ankles

External orthotic supports or braces are used clinically to treat individuals with chronically unstable ankles. Braces have efficacious effects on dynamic strength, passive tissue tension, and proprioception, but their effects on gait remains undetermined. The purpose of this study was to determine if overground locomotion, including walking up a step and a curb are influenced by orthotic device use. Twenty subjects, 10 with no previous injury and 10 with chronically unstable ankles, performed with no brace, a flexible brace and a semi-rigid brace while walking on a level surface, up a step and on a ramp. Differences were noted in kinematic and kinetic gait parameters between groups and between step and ramp conditions, suggesting that gait patterns vary between individuals who have had ankle sprain and those who have not. Few differences were noted between the brace and no brace conditions for both groups. Adding to the previously described efficacious benefits, we conclude that bracing does not alter selected gait parameters in individuals who have chronic ankle instability.

Deficits in detection of inversion and eversion movements among subjects with recurrent ankle sprains

STUDY DESIGN

Observational cross-sectional design.

OBJECTIVES

To determine whether a deficit exists in the ability to perceive inversion and eversion movements among subjects with recurrent ankle sprains.

BACKGROUND

Although unproven, ankle sprains are thought to recur because proprioception is impaired subsequent to the original sprain. Proprioception has been widely studied, however, the specific property of movement perception has not been rigorously examined for both inversion and eversion movements.

METHODS AND MEASURES

The ability to perceive passive inversion and eversion movements imposed at the relaxed ankle was measured in 39 subjects with recurrent ankle sprains (sprainers) and 30 subjects with no history of ankle injury (controls) by an assessor masked to subject group. The 70% detection level for movement perception was determined for 3 velocities, 0.1 degrees/s, 0.5 degrees/s, and 2.5 degrees/s, tested in random order.

RESULTS

The 70% detection level for inversion and eversion movements improved with increasing velocity in both groups. At all velocities, the 70% detection level for movements imposed at the ankle of the sprainers was significantly worse than for controls.

CONCLUSIONS

Perception of passive inversion and eversion movements imposed at the ankle was impaired in subjects with recurrent ankle sprains. The impairment was evident at the 3 velocities tested, 0.1 degrees/s, 0.5 degrees/s, and 2.5 degrees/s.

Sources of variation in spinal indentation testing: indentation site relocation, intraabdominal pressure, subject movement, muscular response, and stiffness estimation

BACKGROUND

Force-displacement properties of spinal tissues assessed by blunt indentation are thought to have clinical relevance; however, numerous variables with respect to spinal indentation have yet to be identified or characterized completely.

OBJECTIVE

To identify and quantify, where possible, previously unidentified or incompletely characterized variables with respect to spinal indentation.

DESIGN

Multiprotocol design.

METHODS

Four experiments were performed: (1) Twelve asymptomatic subjects were indented with concurrent electromyography during conditions of rest, held inspiration, increased intraabdominal pressure and lumbar extension. (2) Changes in the recumbent position of 12 subjects were measured while a series of movements was performed in restrained and unrestrained conditions. (3) Ten clinicians attempted to locate, and to relocate, a subcutaneous anatomical landmark through visualization/palpation and ultrasonic imaging. (4) Performances of 3 methods of force-displacement curve modeling were compared with respect to stiffness estimation.

RESULTS

(1) Spinal stiffness increased significantly in a minority of subjects awaiting indentation and in a majority of subjects during increases in intraabdominal pressure. (2) Changes in subject position were significantly reduced by a restraint system. (3) With respect to interclinician error in locating and relocating an indentation site, there was significant improvement with the use of ultrasonic visualization. (4) The error associated with linear techniques used to model curvilinear force-displacement data plots increased with increasing linear intervals.

CONCLUSION

Several sources of variation in spinal indentation were identified: indentation site relocation, intraabdominal pressure, subject movement, muscular response, and stiffness estimation. These variables, which have been unaccounted for in previous indentation studies, might be responsible for the change or lack of change in force-displacement properties between preintervention and postintervention indentation trials.

Application of passive stretch and its implications for muscle fibers

To increase range of motion, physical therapists frequently use passive stretch as a means of gaining increased excursion around a joint. In addition to clinical studies showing effectiveness, thereby supporting evidence-based practice, the basic sciences can provide an explanation how a technique might work once a technique is known to be effective. The goal of this article is to review the potential cellular events that may occur when muscle fibers are stretched passively. A biomechanical example of passive stretch applied to the ankle is used to provide a means to discuss passive stretch at the cellular and molecular levels. The implications of passive stretch on muscle fibers and the related connective tissue are discussed with respect to tissue biomechanics. Emphasis is placed on structures that are potentially involved in the sensing and signal transduction of stretch, and the mechanisms that may result in myofibrillogenesis are explored.

The effects of ankle compliance and flexibility on ankle sprains

PURPOSE

The goal of this study was to examine the influence of changes in subtalar joint flexibility and compliance on ankle sprain occurrence.

METHODS

Muscle model driven simulations of 10 subjects performing the landing phase of a side-shuffle movement were performed. The passive flexibility or compliance of the subtalar joint was varied, and each subject-specific simulation was exposed to a set of perturbed floor conditions.

RESULTS

Increases in flexibility and compliance both led to an increase in the occurrence of excessive supination, while changes in flexibility had a greater influence. Changes in flexibility or compliance caused only small changes in the occurrence of excessive supination torques.

CONCLUSION

These results suggest that increased mechanical laxity does not directly cause an increase in sprain occurrence during side-shuffle movements.

Ankle sprains and other soft tissue injuries

Lateral ankle sprains are the most frequently encountered injuries in sports. In the evaluation of lateral ankle injury, one should consider all soft tissue structures (i.e., peroneal tendons, ligaments of the ankle, subtalar joints, around the lateral ankle). The treatment of most ankle sprains has evolved from immobilization to functional rehabilitation. Many patients with ankle sprains return to their previous activities. A few patients are left with pain and residual instability after conservative treatment; thus, the question of when to operate on acute severe ankle sprain remains controversial. The other challenge physicians face is the problem of persistent lateral ankle pain after sprain. This condition may be due to intra-articular or extra-articular pathology (i.e., soft tissue lateral ankle impingement, osteochondral lesion, or partial peroneal tendon tear). Diagnosis can be made with careful history, physical examination, and appropriate ancillary studies. Only proper diagnosis can lead to uncompromised, undelayed patient care.