Ankle sensorimotor control and eversion strength after acute ankle inversion injuries

Effects of Inversion Perturbation After Step-Down on the Latency of the Peroneus Longus and Peroneus Brevis

The purpose of this investigation was to determine the effect of different types of ankle sprains on the response latency of the peroneus longus and peroneus brevis to an inversion perturbation, as well as the time to complete the perturbation (time to maximum inversion). To create a forced inversion moment of the ankle, an outer sole with fulcrum was used to cause 25 degrees of inversion at the ankle upon landing from a 27 cm step-down task. Forty participants completed the study: 15 participants had no history of any ankle sprain, 15 participants had a history of a lateral ankle sprain, and 10 participants had a history of a high ankle sprain. There was not a significant difference between the injury groups for the latency measurements or the time to maximum inversion. These findings indicate that a previous lateral ankle sprain or high ankle sprain does not affect the latency of the peroneal muscles or the time to complete the inversion range of motion.

Lateral and syndesmotic ankle sprain injuries: a narrative literature review

OBJECTIVE

The purpose of this article is to review the literature that discusses normal anatomy and biomechanics of the foot and ankle, mechanisms that may result in a lateral ankle sprain or syndesmotic sprain, and assessment and diagnostic procedures, and to present a treatment algorithm based on normal ligament healing principles.

METHODS

Literature was searched for years 2000 to 2010 in PubMed and CINAHL. Key search terms were ankle sprain$, ankle injury and ankle injuries, inversion injury, proprioception, rehabilitation, physical therapy, anterior talofibular ligament, syndesmosis, syndesmotic injury, and ligament healing.

DISCUSSION

Most ankle sprains respond favorably to nonsurgical treatment, such as those offered by physical therapists, doctors of chiropractic, and rehabilitation specialists. A comprehensive history and examination aid in diagnosing the severity and type of ankle sprain. Based on the diagnosis and an understanding of ligament healing properties, a progressive treatment regimen can be developed. During the acute inflammatory phase, the goal of care is to reduce inflammation and pain and to protect the ligament from further injury. During the reparative and remodeling phase, the goal is to progress the rehabilitation appropriately to facilitate healing and restore the mechanical strength and proprioception. Radiographic imaging techniques may need to be used to rule out fractures, complete ligament tears, or instability of the ankle mortise. A period of immobilization and ambulating with crutches in a nonweightbearing gait may be necessary to allow for proper ligament healing before commencing a more active treatment approach. Surgery should be considered in the case of grade 3 syndesmotic sprain injuries or those ankle sprains that are recalcitrant to conservative care.

CONCLUSION

An accurate diagnosis and prompt treatment can minimize an athlete's time lost from sport and prevent future reinjury. Most ankle sprains can be successfully managed using a nonsurgical approach.

Plyometric training versus resistive exercises after acute lateral ankle sprain

BACKGROUND

Plyometric training is a widely used method to improve performance in healthy athletes. It is highly recommended in the late stage of rehabilitation of many lower limb injuries. However, its effects on muscle strength and function in management of lateral ankle sprain have not been reported. Therefore, the objective of the current study was to determine the effects of plyometric training versus resistive exercises on muscle strength and function following acute lateral ankle sprain.

MATERIALS AND METHODS

Twenty-two athletes (aged from 20 to 35 years) of both sexes with grade I or II unilateral inversion ankle sprain participated in the study (at least 3 weeks after acute injury). They were randomly assigned to two groups. The first group received plyometric training, whereas the second one received resistive training for 6 weeks. Isokinetic peak torque/body weight for invertors and evertors at 30 degrees/s and 120 degrees/s and functional tests were assessed before and after training.

RESULTS

Both plyometric and resistive training improve isokinetic evertor and invertor peak torques and functional performance of athletes p < 0.05. There were no significant differences between groups concerning peak torque/body weight for invertors and evertors at both speeds measured p > 0.05. The functional test measures of the plyometric group were significantly higher than that of resistive group.

CONCLUSION

Plyometrics were more effective than resistive exercises in improving functional performance of athletes after lateral ankle sprain.

Análise da influência da bandagem funcional de tornozelo no tempo de reação do fibular longo em sujeitos saudáveis

OBJETIVOS: O objetivo deste estudo foi analisar a influência da bandagem funcional de tornozelo no tempo de reação do fibular longo de indivíduos sadios. MÉTODOS: A amostra foi composta por oito indivíduos do gênero masculino, fisicamente ativos, sem histórias prévias de lesões de tornozelo e, com os resultados negativos aos testes de instabilidade articular de tornozelo. Foram usados como instrumentos da pesquisa, a bandagem funcional de tornozelo tipo bota fechada, para realizar o teste uma plataforma capaz de inclinar 30o no plano frontal simulando a entorse lateral do tornozelo e um eletromiógrafo de oito canais (Bortec Electronics Incorporation, Canadá) para aquisições dos sinais eletromiográficos. Os sinais EMG foram coletados juntamente com o sinal da plataforma (sincronismo). A coleta dos dados foi realizada em dois momentos, primeiramente sem a bandagem e logo após com a bandagem. RESULTADOS: Os indivíduos tinham idade média de 23,3 anos (± 2,8), massa corpórea de 74,4kg (± 9,4), estatura de 1,7m (± 0,4) e IMC de 23,7kg/m2 (± 2,4). O estudo encontrou diferença estatisticamente significativa p = 0,018 na situação da bandagem funcional de tornozelo com diminuição do tempo de reação do fibular longo. CONCLUSÃO: Acreditamos que esta melhora se deva ao íntimo contato da bandagem com os receptores cutâneos do tornozelo, aumentando a ativação do reflexo fibular, com consequente ganho proprioceptivo e, assim, aumentando a habilidade dos sujeitos em responder a situações súbitas de entorses. O estudo demonstrou diminuição no tempo de reação do fibular longo de indivíduos sadios com o uso da bandagem funcional de tornozelo quando submetidos à inclinação lateral súbita do tornozelo.

Neuromuscular control and ankle instability

Lateral ankle sprains (LAS) are common injuries in athletics and daily activity. Although most are resolved with conservative treatment, others develop chronic ankle instability (AI)-a condition associated with persistent pain, weakness, and instability-both mechanical (such as ligamentous laxity) and functional (neuromuscular impairment with or without mechanical laxity). The predominant theory in AI is one of articular deafferentation from the injury, affecting closed-loop (feedback/reflexive) neuromuscular control, but recent research has called that theory into question. A considerable amount of attention has been directed toward understanding the underlying causes of this pathology; however, little is known concerning the neuromuscular mechanisms behind the development of AI. The purpose of this review is to summarize the available literature on neuromuscular control in uninjured individuals and individuals with AI. Based on available research and reasonable speculation, it seems that open-loop (feedforward/anticipatory) neuromuscular control may be more important for the maintenance of dynamic joint stability than closed-loop control systems that rely primarily on proprioception. Therefore, incorporating perturbation activities into patient rehabilitation schemes may be of some benefit in enhancing these open-loop control mechanisms. Despite the amount of research conducted in this area, analysis of individuals with AI during dynamic conditions is limited. Future work should aim to evaluate dynamic perturbations in individuals with AI, as well as subjects who have a history of at least one LAS and never experienced recurrent symptoms. These potential findings may help elucidate some compensatory mechanisms, or more appropriate neuromuscular control strategies after an LAS event, thus laying the groundwork for future intervention studies that can attempt to reduce the incidence and severity of acute and chronic lateral ankle injury.

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.

Relationship between functional ankle instability and postural control

STUDY DESIGN

Controlled laboratory study using a cross-sectional design.

OBJECTIVES

To investigate the relationship between postural control and functional ankle instability during a hop-landing task, and to investigate whether postural control is altered in people with functional ankle instability.

METHODS AND MEASURES

Sixty volunteers classified by the Cumberland Ankle Instability Tool (CAIT) scores formed the external control group (CAIT score, >or= 28, n = 31) and the instability group (CAIT score, <or= 27 and history of at least 1 ankle sprain; n = 29). Postural control was measured with the landing test, in which participants stood on 1 lower extremity for 3 seconds on a step, then hopped down onto a force plate and regained postural stability after landing. The main outcome measurements were time to stability (TTS) after landing for ankle inversion, dorsiflexion, and summated electromyographic (EMG) signal amplitude for the tibialis anterior, soleus, and fibularis longus. The secondary outcomes were the proportion of movement in the frontal plane for hip and ankle, the variability of inversion movement prior to hopping, and the variables from ground reaction force.

RESULTS

There were no associations (P > .05) between the CAIT scores and the TTS for ankle inversion (r = -0.25), dorsiflexion (r = -0.04), summated EMG (r = -0.13) and proportion of movement in the frontal plane (r = 0.005). Participants in the instability group took longer to regain stability in inversion and displayed greater inversion variability prejump than the control group (P = .05 and .009, respectively).

CONCLUSIONS

Ankle inversion control is affected in people with functional ankle instability in tasks of postural control after landing from a hop.

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.

Sensorimotor deficits with ankle sprains and chronic ankle instability

The presence of sensorimotor deficits in patients who have suffered ankle sprains or who have chronic ankle instability has been recognized for several decades; however, a body of research literature has developed that elucidates potential physiologic explanations for these deficits. Alterations in a spectrum of sensorimotor measures make it apparent that conscious perception of afferent somatosensory information, reflex responses, and efferent motor control deficits are present with ankle instability. The specific origin of these deficits local to the ankle ligaments or at the spinal or supraspinal levels of motor control have yet to be fully elucidated. It is clear, however, that both feedback and feedforward mechanisms of motor control are altered with ankle instability.

The deficit of joint position sense in the chronic unstable ankle as measured by inversion angle replication error

INTRODUCTION

Functional instability is defined as a repeated ankle inversion sprain and a giving way sensation. Previous studies have described the damage of sensori-motor control in ankle sprain as being a possible cause of functional instability. The aim of this study was to evaluate the inversion angle replication errors in patients with functional instability after ankle sprain.

MATERIALS AND METHODS

The difference between the index angle and replication angle was measured in 12 subjects with functional instability, with the aim of evaluating the replication error. As a control group, the replication errors of 17 healthy volunteers were investigated. The side-to-side differences of the replication errors were compared between both the groups, and the relationship between the side-to-side differences of the replication errors and the mechanical instability were statistically analyzed in the unstable group.

RESULTS

The side-to-side difference of the replication errors was 1.0 +/- 0.7 degrees in the unstable group and 0.2 +/- 0.7 degrees in the control group. There was a statistically significant difference between both the groups. The side-to-side differences of the replication errors in the unstable group did not statistically correlate to the anterior talar translation and talar tilt.

CONCLUSION

The patients with functional instability had the deficit of joint position sense in comparison with healthy volunteers. The replication error did not correlate to the mechanical instability. The patients with functional instability should be treated appropriately in spite of having less mechanical instability.

The effect of fatigue and habituation on the stretch reflex of the ankle musculature

Many ankle injuries are said to occur when athletes are in a fatigued state; therefore, studies investigating the role that fatigue plays in ankle injuries are warranted. Furthermore, the contributions of the stretch reflex in countering the injury mechanism are still unclear. We hypothesized that (1) fatigue would impair the reflex response, (2) there would be no differences between genders, (3) habituation would be present, and (4) fatigue would exacerbate the effect of habituation. Forty healthy subjects participated and were divided into treatment and control groups. Stretch reflex measurements were taken for the tibialis anterior (TA), peroneus longus (PL), and peroneus brevis (PB) muscles in response to a rapid inversion perturbation. A fatigue intervention was administered to the treatment group, while the control group sat quietly. Post-test measurements were recorded within 5min and reflex latency (RL) and amplitude (RA) were calculated. RA decreased significantly, however a significant improvement was noted in RL in the PL and PB muscles. The effect that peripheral fatigue has on RL should not be considered a cause of ankle injuries. However, the diminished RA may suggest reduced dynamic stability after fatigue. Habituation was present and was exacerbated by fatigue, indicating that reflex testing is affected by fatigue and habituation, which must be taken into consideration in future studies.

Effect of isokinetic training on strength, functionality and proprioception in athletes with functional ankle instability

The purpose of this study was to investigate the effects of isokinetic exercise on strength, joint position sense and functionality in recreational athletes with functional ankle instability (FAI). Strength, proprioception and balance of 24 recreational athletes with unilateral FAI were evaluated by using isokinetic muscle strength measurement, ankle joint position sense and one leg standing test. The functional ability was evaluated using five different tests. These were; single limb hopping course (SLHC), one legged and triple legged hop for distance (OLHD-TLHD), and six and cross six meter hop for time (SMHT-CSMHT). Isokinetic peak torque of the ankle invertor and evertor muscles were assessed eccentrically and concentrically at test speeds of 120 degrees /s. Isokinetic exercise protocol was carried out at an angular velocity of 120 degrees /s. The exercise session was repeated three times a week and lasted after 6 weeks. At baseline, concentric invertor strength was found to be significantly lower in the functionally unstable ankles compared to the opposite healthy ankles (p < 0.001). This difference was not present after executing the 6 weeks exercise sessions (p > 0.05). Ankle joint position sense in the injured ankles declined significantly from 2.35 +/- 1.16 to 1.33 +/- 0.62 degrees for 10 degrees of inversion angle (p < 0.001) and from 3.10 +/- 2.16 to 2.19 +/- 0.98 degrees for 20 degrees of inversion angle (p < 0.05) following the isokinetic exercise. One leg standing test score decreased significantly from 15.17 +/- 8.50 to 11.79 +/- 7.81 in the injured ankles (p < 0.001). Following the isokinetic exercise protocol, all of the worsened functional test scores in the injured ankles as compared to the opposite healthy ankles displayed a significant improvement (p < 0.01 for OLHD and CSMHT, p < 0.001 for SLHC, TLHD, and SMHT). These results substantiate the deficits of strength, proprioception, balance and functionality in recreational athletes with FAI. The isokinetic exercise program used in this study had a positive effect on these parameters.

Dynamic Postural Stability Deficits in Subjects with Self-Reported Ankle Instability

PURPOSE

A limited understanding of how functional ankle instability (FAI) affects dynamic postural stability exists because of a lack of reliable and valid measures. Therefore, the purpose of this investigation was to determine whether a new reliable index for dynamic postural stability could differentiate between those with stable ankles and those with FAI.

METHODS

Data were collected on 108 subjects (54 subjects with stable ankles (STABLE group); 54 subjects with functionally unstable ankles (FAI group)). Subjects performed a single-leg-hop stabilization maneuver in which they stood 70 cm from the center of a force plate, jumped off both legs, touched a designated marker placed at a height equivalent to 50% of their maximum vertical leap, and landed on a single leg. The dynamic postural stability index and directional stability indices (medial/lateral, anterior/posterior, and vertical) were calculated. The raw and normalized (to energy dissipated) indices were compared between groups.

RESULTS

Significant differences were noted for the anterior/posterior stability index (FAI = 0.36 +/- 0.09, STABLE = 0.30 +/- 0.06). Similar results were seen for the vertical stability index (FAI = 0.73 +/- 0.17, STABLE = 0.61 +/- 0.13), the normalized dynamic postural stability index (FAI = 0.85 +/- 0.17, STABLE = 0.73 +/- 0.12), the normalized vertical stability index (FAI = 0.007 +/- 0.004, STABLE = 0.005 +/- 0.001), and the dynamic postural stability index (FAI = 0.008 +/- 0.003, STABLE = 0.006 +/- 0.001).

CONCLUSIONS

These results indicate that the dynamic postural stability index is a sensitive measure of dynamic postural stability and is capable of detecting differences between individuals with stable ankles and individuals with functionally unstable ankles.

Are there any relationships among ankle proprioception acuity, pre-landing ankle muscle responses, and landing impact in man?

Proprioceptive input has been suggested to contribute to the pre-landing muscle responses associated with drop-landing, but its precise role has yet to be delineated. This study set out to examine the relationships among ankle proprioception, pre-landing muscle responses, and landing impact on drop-landing in healthy man. Fifteen healthy male basketball players aged 18 to 26 participated in this study. Passive ankle joint repositioning errors were used to examine ankle joint proprioception. Pre-landing EMG responses in the ankle muscles and the impact force on landing were recorded while the players performed self-initiated drops from a height of 30 cm. Results demonstrated that averaged ankle repositioning errors were significantly correlated with the co-contraction indexes between left tibialis anterior and medial gastrocnemius muscles (TA/MG CoI) (r=0.67, p=0.006), and showed a trend towards a relationship with the right TA/MG CoI (r=0.47, p=0.079). TA/MG CoI from both ankles were further related to the magnitude of the total impact force on landing (r=0.54 and 0.53, respectively; p<0.05). We concluded that male basketball players with less accurate ankle joint sense adopted greater co-contraction of ankle dorsiflexors and platarflexors, which was in turn associated with greater impact force at the moment of landing.

Ground reaction force in basketball cutting maneuvers with and without ankle bracing and taping

CONTEXT AND OBJECTIVE

In basketball, the most common injuries are ankle sprains. For this reason, players frequently use external ankle devices or taping as prophylactic and rehabilitation measures. The purpose of this study was to evaluate ground reaction force (GRF) responses in basketball players while performing typical cutting maneuvers with and without ankle bracing and ankle taping.

DESIGN AND SETTING

Comparative study with experimental design of single-group repeated measurements, at Medical Rehabilitation Division, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo.

METHODS

Vertical (Fy) and medial-lateral (Fz) GRF measurements were made under three conditions (taping, Aircast-type orthosis and basketball shoes alone), with analysis of peak forces at foot contact (Fymax1, Fzmax1, Fymax2 and Fzmax2), growth gradient (peak/time) (GG Fymax1, GG Fzmax1, GG Fymax2 and GG Fzmax2) and impulse after foot contact.

RESULTS

Bracing significantly reduced Fymax2 and GG Fymax2. GG Fzmax1 was significantly higher for the sport shoe condition than for the taping condition. Taping increased Fy in relation to the sport shoe at foot contact, but over a longer time interval, without increasing excessive ankle loading. Fz reached a peak in less time, which might generate greater inversion/eversion loading on a player's foot. The Aircast exerted better shock-absorbing effect than did the other two conditions, since it generated less vertical force over longer time intervals and smaller medial-lateral forces in relation to taping.

CONCLUSIONS

Ankle bracing and ankle taping action mechanisms are still unclear and therefore should be carefully prescribed. More studies are needed to clarify taping and bracing effects on sporting activities.

Dance-Related Injury

Although dance medicine has derived extensive knowledge from sports medicine, some aspects covered in the practice of dance medicine are unique to this field. Acute and overuse injuries must be analyzed within the scope of associated mechanisms of injury, mainly related to the practice of specific dance techniques. Even though most available medical literature concerning dance medicine is specific to ballet-related conditions, many of the concepts covered here and in other articles can be helpful in the treatment and diagnosis of participants in other dance disciplines. Continued research is expanding the knowledge on injury patterns of different dance disciplines. It is the experience of dance practitioners that dancers are quite in touch with their bodies; thus, when their ailments are systematically analyzed, and underlying cause can usually be identified. In this sense, it is evident that the principles of dance medicine and rehabilitation allow the practitioner to arrive at a diagnosis and treat the underlying causes to prevent reinjury, ameliorate sequelae from injury, and minimize residual deficits after injury.

Physical therapy following peripheral nerve surgeries

Post-operative care of the surgical patient significantly contributes to the success of the surgical procedure. Post-operative physical therapy is directed at reducing pain and inflammation, preventing or minimizing scar tissue, and returning the patient to full function. An individualized and well-planned therapeutic exercise program is an integral part of the post-operative care. Manual therapy techniques are utilized to break up scar tissue and reduce joint stiffness. Pain and inflammation can be addressed by modalities such as ultrasound, laser, and electrical stimulation in addition to cryotherapy.

Contralateral force sense deficits are related to the presence of functional ankle instability

Residual symptoms that often follow lateral ankle sprains can lead to functional ankle instability. Proprioceptive deficits have been identified as one factor that may contribute to the presence of functional ankle instability. Sixty participants were recruited to participate in the study. Seven questions were used to determine the presence of functional ankle instability in each participant. A point was added for each "yes" response to produce an index that represents an interval data scale of functional ankle instability. Contralateral force sense and active joint reposition sense were measured in all participants. Pearson product moment correlations were calculated to determine the relationship between functional ankle instability and force sense and active joint reposition sense. We found a significant relationship with force sense and functional ankle instability. Specifically, force sense variable error at both test forces (10 and 30% of maximal voluntary isometric contraction) were positively correlated to the presence of functional ankle instability, r=0.26; p<or=0.05 and r=0.25; p<or=0.05, respectively. All other force sense correlations were not statistically significant. No significant correlations were identified between active joint reposition sense and functional ankle instability. This study indicates that participants with functional ankle instability have deficits in low load force sense, but not active joint reposition sense.

Effects of neuromuscular training on the reaction time and electromechanical delay of the peroneus longus muscle

OBJECTIVE

To examine the influence of a 6-week neuromuscular training program on the electromechanical delay and reaction time of the peroneus longus muscle.

DESIGN

A 2 x 2 pre-post factorial design.

SETTING

Human performance research center biomechanics laboratory.

PARTICIPANTS

Thirty-six healthy, physically active, college-age subjects were recruited for this study and 26 completed it. There were 5 men and 8 women in the treatment group (mean age +/- standard deviation, 21.9+/-2.1 y; height, 173.7+/-11.1cm; weight, 67.4+/-17.8 kg) and 6 men and 7 women in the control group (age, 21.8+/-2.3 y; height, 173.7+/-11.9 cm; weight, 70.8+/-19.4 kg). Subjects were not currently experiencing any lower-extremity pathology and had no history of injuries requiring treatment to either lower extremity.

INTERVENTIONS

Subjects in the treatment group completed a 6-week neuromuscular training program involving various therapeutic exercises. Subjects in the control group were asked to continue their normal physical activity during the 6-week period.

MAIN OUTCOME MEASURES

The electromechanical delay of the peroneus longus was determined by the onset of force contribution after artificial activation, as measured by electromyographic and forceplate data. Reaction time was measured after a perturbation during walking. Data were analyzed using two 2 x 2 analyses of covariance (covariate pretest score). Group (treatment, control) and sex (male, female) were between-subject factors.

RESULTS

Neuromuscular training caused a decrease in reaction time to perturbation during walking compared with controls (F=4.030, P=.029), while there was a trend toward an increase in electromechanical delay (F=4.227, P=.052). There was no significant difference between sexes or the interaction of sex and treatment in either reaction time or electromechanical delay.

CONCLUSIONS

The 6-week training program significantly reduced reaction time of the peroneus longus muscle in healthy subjects. Neuromuscular training may have a beneficial effect on improving dynamic restraint during activity.

Ankle function during gait in patients with chronic ankle instability compared to controls

BACKGROUND

Despite much research, the reasons behind the development of chronic ankle instability in individuals post ankle inversion sprain are unknown. Chronic ankle instability has not previously been investigated dynamically using 3D motion analysis during walking. We hypothesised that chronic ankle instability subjects would exhibit a different kinematic and kinetic pattern during normal walking when compared with a control group.

METHODS

Gait analysis was carried out on fifty subjects (25 chronic ankle instability, and 25 age, gender, activity, and gait velocity matched controls) during walking. Kinematic and kinetic pattern differences using the 3D motion analysis system combined with a force plate were established during 100 ms pre-heel strike and 200 ms post-heel strike, between the chronic ankle instability subjects and controls during normal walking.

FINDINGS

Chronic ankle instability subjects were significantly (P<0.01) more inverted in the frontal plane compared to controls from 100 ms pre-heel strike to 200 ms post-heel strike. The joint angular velocity was significantly (P<0.05) higher at heel strike in the chronic ankle instability group. During the early stance phase of gait chronic ankle instability subjects appear to be controlled by an evertor muscle moment working concentrically compared to an invertor muscle moment working eccentrically in the controls.

INTERPRETATION

These changes in kinematics and kinetics which arise are likely to result in increased stress being applied to ankle joint structures during the heel strike and loading response phases of the gait cycle. This could result in repeated injury and consequent damage to ankle joint structures.

Repeated ankle sprains and delayed neuromuscular response: acceleration time parameters

STUDY DESIGN

A comparative study.

OBJECTIVES

To assess whether in subjects with unilateral chronic ankle instability the dynamic reaction time of the affected ankle differs from the healthy ankle and from ankles of a control group.

BACKGROUND

Reaction time is an essential element in joint protection against sudden unexpected excessive movement requiring fast and coordinated muscle action. During a sudden ankle inversion movement, a reflex action of the evertor muscles is needed to counteract the movement. Adequate neuromuscular response is crucial and a delayed response could contribute to inversion trauma and subsequently to chronic ankle instability. The isokinetic dynamometer acceleration time (ACC-TIME) provides valuable information on dynamic neuromuscular ability.

MATERIAL AND METHODS

Patients with unilateral chronic ankle instability (n = 11) and healthy individuals in a control group (n = 11) were tested on an isokinetic dynamometer during 3 sets of 3 reciprocal inversion/eversion movements of both ankles at 30 degrees/s and 120 degrees/s. Analysis of variance models were used to compare the ACC-TIME of the affected ankle to the unaffected ankle of the same subjects and a control group.

RESULTS

For the evertor muscles at 30 degrees/s and 120 degrees/s a significantly prolonged ACC-TIME was found when comparing the affected ankles to the contralateral ankles and both ankles of the control group. For the invertor muscles at 120 degrees/s a significantly prolonged ACC-TIME was found when comparing the affected ankle to the unaffected ankles of patients and those of the control group.

CONCLUSIONS

Because the most important evertor muscles are innervated by the fibular nerve, the significantly prolonged ACC-TIME of the affected ankle is consistent with the finding of a lower motor nerve conduction velocity of the fibular nerve after inversion trauma. The results support the concept of a delayed neuromuscular response as an important factor in the etiology of chronic ankle instability.

Intrinsic risk factors for inversion ankle sprains in females--a prospective study

Ankle sprains are extremely common. However, very little is known about the variables that predispose individuals to these injuries. The purpose of this study was to examine prospectively intrinsic risk factors for inversion sprains in a young physically active female population. One hundred and fifty-nine female physical education students were evaluated for several possible intrinsic risk factors for inversion sprains at the beginning of their academic study. The evaluated intrinsic risk factors included anthropometrical and physical characteristics, ankle joint position sense, isokinetic ankle muscle strength, lower leg alignment characteristics, postural control and muscle reaction time during a sudden inversion perturbation. All sports injuries were registered during 1-3 years and exposure to sport was recorded (mean: 15.33+/-4.33 h a week). Thirty-two (20%) of the 159 females sprained their ankle. The number of ankle sprains per 1000 h of sports exposure was 0.75. The Cox regression analysis revealed that females with less accurate passive joint inversion position sense [hazard ratio (HR): 1.08, 95% confidence interval (CI): 1.02-1.14 for absolute error at 15 degrees inversion], a higher extension range of motion at the first metatarsophalangeal joint (HR: 1.03, 95% CI: 1.00-1.06) and less coordination of postural control (HR: 0.96, 95% CI: 0.93-1.00 for endpoint excursion; HR: 0.94, 95% CI: 0.89-0.99 for maximal endpoint excursion) are at greater risk of an ankle sprain. The findings of this study suggest that effective prevention and conservative rehabilitation of ankle inversion sprains should include attention to these variables.

Measurement and Evaluation of Dynamic Joint Stability of the Knee and Ankle After Injury

Injuries to the lower extremity, specifically the knee and ankle joints of the human body can occur in any athletic event and are most prevalent in sports requiring cutting and jumping manoeuvres. These joints are forced to rely on the dynamic restraints to maintain joint stability, due to the lack of bony congruence and the inability of the static restraints to handle the forces generated during functional tasks. Numerous variables (proprioception, postural control, electromyography, kinetics/kinematics, dynamic stability protocols) have been measured to better understand how the body maintains joint stability during a wide range of activities from static standing to dynamic cutting or landing from a jump. While the importance of dynamic restraints is not questioned, a recent impetus to conduct more functional or sport-specific testing has emerged and placed a great deal of emphasis on dynamic joint stability and how it is affected by lower extremity injuries. Evidence suggests that surgery and aggressive rehabilitation will not necessarily restore the deficits in dynamic joint stability caused by injury to the anterior cruciate ligament or lateral ankle ligaments. In today's athletic society, there is a major push to return athletes to play as quickly as possible. However, the ramifications of those decisions have not been fully grasped. If an athlete is not fully recovered, a quick return to play could start a vicious cycle of chronic injuries or permanent disability.

Avaliação do tempo de resposta eletromiográfica em atletas de voleibol e não atletas que sofreram entorse de tornozelo

A proposta deste estudo foi examinar o tempo de resposta eletromiográfica dos músculos fibulares, na inversão repentina do pé, em tornozelos com presença de lesão e saudáveis. Três grupos foram testados, um de atletas normais (grupo 1), um de atletas com história recente de entorse de tornozelo (grupo 2) e o outro de não atletas com história recente de entorse de tornozelo (grupo 3). Para cada sujeito dos três grupos, ambos os tornozelos foram testados. Os sujeitos que sofreram entorse de tornozelo (grupos 2 e 3) não apresentavam sintomas de lesão durante os últimos dois meses antes do teste. Uma plataforma capaz de produzir uma inversão repentina lateral de 20° do tornozelo no plano frontal simulava um evento de entorse de tornozelo. Eletrodos de eletromiografia de superfície foram colocados na pele sobre os músculos fibulares. Os tempos de resposta eletromiográfica dos músculos fibulares foram obtidos e comparados entre os grupos. Para o grupo 1, a média dos tempos de resposta eletromiográfica foi de 71ms para a perna direita e 69ms para a perna esquerda. Para o grupo 2, a média dos tempos de resposta eletromiográfica foi de 72ms para o tornozelo sem lesão e 74ms para o tornozelo com a lesão. Para o grupo 3, a média dos tempos de resposta eletromiográfica foi de 72ms para o tornozelo sem lesão e 73ms para o tornozelo com a lesão. Os resultados indicaram que não houve diferença estatisticamente significante entre as pernas direita e esquerda no grupo 1 e entre os tornozelos sem lesão e com lesão dos grupos 2 e 3 para os músculos fibulares. Os achados do presente estudo sugerem que a resposta eletromiográfica dos músculos fibulares, durante o deslocamento angular repentino do tornozelo, não foi influenciada pela entorse de tornozelo.

Arthrogenic muscle inhibition in the leg muscles of subjects exhibiting functional ankle instability

BACKGROUND

Functional ankle instability or a subjective report of ;;giving way'' at the ankle may be present in up to 40% of patients after a lateral ankle sprain. Damage to mechanoreceptors within the lateral ankle ligaments after injury is hypothesized to interrupt neurologic feedback mechanisms resulting in functional ankle instability. The altered input can lead to weakness of muscles surrounding a joint, or arthrogenic muscle inhibition. Arthrogenic muscle inhibition may be the underlying cause of functional ankle instability. Establishing the involvement of arthrogenic muscle inhibition in functional ankle instability is critical to understanding the underlying mechanisms or chronic ankle instability. The purpose of this investigation was to determine if arthrogenic muscle inhibition is present in the ankle joint musculature of patients exhibiting unilateral functional ankle instability.

METHODS

Twenty-nine subjects, 15 with unilateral functional ankle instability and 14 healthy control subjects, consented to participate. Bilateral soleus, peroneal, and tibialis anterior H-reflex and M-wave recruitment curves were obtained. Maximal H-reflex and maximal M-wave values were identified and the H:M ratios were calculated for data analysis. Separate 1 x 2 ANOVA were done for both the functional ankle instability and control groups to evaluate differences between limbs on the H:M ratios. Bonferroni multiple comparison procedures were used for post hoc comparisons (p < or = 0.05).

RESULTS

The soleus and peroneal H:M ratios for subjects with functional ankle instability were smaller in the injured limb when compared with the uninjured limb (p < 0.05). No limb difference was detected for the tibialis anterior H:M ratio in the functional ankle instability group (p = 0.904). No side-to-side differences were detected for the H:M ratios in patients reporting no history of ankle injury (p > 0.05).

CONCLUSIONS

Depressed H:M ratios in the injured limb suggest that arthrogenic muscle inhibition is present in the ankle musculature of patients exhibiting functional ankle instability. Establishing and using therapeutic techniques to reverse arthrogenic muscle inhibition may reduce the incidence of functional ankle instability.

Evidence-based treatment of foot and ankle injuries in runners

Foot and ankle injuries are common in runners. Treatment is becoming more evidence-based for the most common of these conditions; however, further research is needed to determine the best treatments for injuries that are encountered less commonly.

Influence of professional dance training on peak torque and proprioception at the ankle

OBJECTIVE

To investigate the influence of professional dance training on the peak torque ratio of plantar flexion to dorsiflexion (PF/DF), angle replication ability, and balance in comparison to age-matched and gender-matched controls. The effects of injuries sustained before and during the study time period were also assessed.

DESIGN

Prospective age-matched and gender-matched nonrandomized intervention study.

SETTING

Premises of the Orthopedic University Hospital, Heidelberg, where measuring apparatus belonging to the hospital was used for the tests.

PARTICIPANTS

One group of 42 dancers (31 female, 11 male) in professional training (State Academy) and 40 age-matched and gender-matched controls with no prior dance or specific sport training.

MAIN OUTCOME MEASUREMENTS

Isokinetic tests for peak torque at 30 degrees /s and 120 degrees /s, a passive angle-replication test (Biodex system 3), and a test of 1-legged standing were each carried out on 2 measurement dates (M1, M2): at the beginning of a season of professional dance training (M1) and after 5 months of such training (M2). Symptoms and/or injuries sustained during this period were ascertained continuously by means of questionnaires and interviews.

RESULTS

A significant increase in peak torque in PF was observed in both dancer groups and male controls between M1 and M2. A significant increase in PF/DF peak torque ratio at 30 degrees /s was observed in both male groups between M1 and M2. At M2, no significant differences in PF/DF peak torque ratio could be found between male dancers and controls, but at 30 degrees /s between the female groups. However, in both female groups, the PF/DF ratio was not found to increase significantly between M1 and M2. In the angle-replication and 1-legged standing test, no consistent improvement was observed between M1 and M2 in either dancers or controls. In the angle-replication test, there were no significant differences between dancers and controls at M2. In the 1-legged standing test, the dancers did significantly better than controls. A total of 7 ankle injuries were recorded, but no difference was found between injured and uninjured subjects in the proprioceptive tests either at M1, as the predicator, or at M2 as the residual.

CONCLUSIONS

Dance training did not increase the peak torque ratio of PF/DF within 5 months, but a group difference was found between the women groups. Ballet training alone without concurrent additional coordinative training does not lead to improvements in ankle joint position sense or improved measures of balance within this period of observation.

Peroneus longus muscle activation pattern during gait cycle in athletes affected by functional ankle instability: a surface electromyographic study

BACKGROUND

Functional ankle instability is a clinical syndrome that may develop after acute lateral ankle sprain. Although several causes of this functional instability have been suggested, it is still unclear what the activation pattern of the peroneus longus muscle is in patients with functional ankle instability.

HYPOTHESIS

Peroneus longus activation patterns differ in the injured side and the uninjured side in subjects with functional ankle instability.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The authors examined 14 subjects with functional ankle instability by using surface electromyography during walking. Activation time of the peroneus longus muscle was expressed as a percentage of the stance phase of the gait cycle.

RESULTS

A statistically significant decrease in peroneus longus muscle activity was found in the injured side compared with the uninjured side (22.8% +/- 4.25% vs 37.6% +/- 3.5%, respectively).

CONCLUSIONS

Results obtained in this study show a change in peroneus longus muscle activation time after injury. Independent of the origin of this change, which could only be surmised, the decrease in peroneus longus muscle activity may result in reduced protection against lateral sprains.

CLINICAL RELEVANCE

The assessment of peroneus longus activation pattern during gait is useful to design an appropriate rehabilitation program in athletes suffering from functional ankle instability.

Ankle joint proprioception and postural control in basketball players with bilateral ankle sprains

BACKGROUND

Deficiencies in ankle proprioception and standing balance in basketball players with multiple ankle sprains have been reported in separate studies. However, the question of how ankle proprioceptive inputs and postural control in stance are related is still unclear.

HYPOTHESIS

Ankle repositioning errors and the amount of postural sway in stance are increased in basketball players with multiple ankle sprains.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty healthy male basketball players and 19 male basketball players who had suffered bilateral ankle sprains within the past 2 years were examined. Both groups were similar in age. Passive ankle joint repositioning errors at 5 degrees of plantar flexion were used to test for ankle joint proprioception. The Sensory Organization Test was applied with dynamic posturography to assess postural sway angle under 6 sensory conditions.

RESULTS

A significant increase in ankle repositioning errors was demonstrated in basketball players with bilateral ankle sprains (P < .05). The mean errors in the right and left ankles were increased from 1.0 degrees (standard deviation, 0.4 degrees ) and 0.8 degrees (standard deviation, 0.2 degrees ), respectively, in the healthy players to 1.4 degrees (standard deviation, 0.7 degrees ) and 1.1 degrees (standard deviation, 0.5 degrees ) in the injured group. A significant increase in the amount of postural sway in the injured subjects was also found in conditions 1, 2, and 5 of the Sensory Organization Test (P < .05). Furthermore, there were positive associations between averaged errors in repositioning both ankles and postural sway angles in conditions 1, 2, and 3 of the Sensory Organization Test (r = 0.39-0.54, P < .05).

CONCLUSIONS

Ankle repositioning errors and postural sway in stance increased in basketball players with multiple ankle sprains. A positive relationship was found between these 2 variables.

CLINICAL RELEVANCE

Such findings highlight the need for the rehabilitation of patients with multiple ankle sprains to include proprioceptive and balance training.

Intrinsic risk factors for inversion ankle sprains in male subjects: a prospective study

BACKGROUND

Many variables have been retrospectively associated with ankle sprains. However, very little is known about factors predisposing people to these injuries.

HYPOTHESIS

Measurable intrinsic factors might predispose male athletes to ankle sprains.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 241 male physical education students were evaluated for possible intrinsic risk factors for inversion sprains at the beginning of their academic study. The evaluated intrinsic risk factors included anthropometrical characteristics, functional motor performances, ankle joint position sense, isokinetic ankle muscle strength, lower leg alignment characteristics, postural control, and muscle reaction time during a sudden inversion perturbation. Subjects were followed prospectively for 1 to 3 years.

RESULTS

A total of 44 (18%) of the 241 male subjects sustained an inversion sprain; 4 sprained both ankles. Cox regression analysis revealed that male subjects with slower running speed, less cardiorespiratory endurance, less balance, decreased dorsiflexion muscle strength, decreased dorsiflexion range of motion, less coordination, and faster reaction of the tibialis anterior and gastrocnemius muscles are at greater risk of ankle sprains.

CONCLUSION

Based on our findings, it is suggested that running speed, cardiorespiratory endurance, balance, dorsiflexion strength, coordination, muscle reaction, and dorsiflexion range of motion at the ankle are associated with the risk of ankle inversion sprains in male subjects.

Influência de implementos para o tornozelo nas respostas biomecânicas do salto e aterrissagem no basquete

FUNDAMENTOS E OBJETIVO: O segmento mais freqüentemente lesado no basquetebol é o tornozelo, sendo a entorse por inversão a lesão mais comum. Para evitá-la, é comum o uso de implementos. O objetivo deste estudo foi avaliar a força reação do solo (FRS) em jogadores de basquete durante execução do salto em três situações: uso de tênis, bandagem e tênis, e tênis e órtese tipo Aircast. MÉTODOS: Oito atletas foram analisados durante o salto, através de uma plataforma de força, nas três situações citadas, para análise das componentes vertical e horizontal médio-lateral da FRS. RESULTADOS E CONCLUSÃO: Não houve diferença estatística significativa entre as três situações na componente vertical da FRS durante o salto, embora o uso de bandagem tenda a apresentar, na impulsão, maiores valores do pico de força vertical (3,10 ± 0,46PC; 3,01 ± 0,39PC; 3,03 ± 0,41PC) e do gradiente de crescimento (GC) (12,33 ± 12,21PC; 8,16 ± 3,89PC; 8,46 ± 3,85PC), e durante a aterrissagem, menores valores de pico de força vertical (5,18 ± 1,35PC; 5,56 ± 1,31PC; 5,49 ± 1,44PC) e do GC (88,83 ± 33,85PC; 95,63 ± 42,64PC; 94,53 ± 31,69PC). Durante a impulsão, a força medial do salto com Aircast foi significativamente menor que com tênis (p = 0,0249) e apresentou valor semelhante ao do uso da bandagem, enquanto a força lateral foi significativamente maior com a bandagem do que com tênis (p = 0,0485) e tendeu a ser maior do que o Aircast. Na aterrissagem o componente médio-lateral da FRS ficou inalterado nas três situações. Concluiu-se que a bandagem potencializou a força direcionada ao salto vertical durante a impulsão, porém não estabilizou tanto quanto o Aircast os movimentos de inversão e eversão do pé. Durante a aterrissagem, os implementos não foram efetivos para reduzir a força médio-lateral, mas com a bandagem, houve um tempo maior para absorção do impacto.

Effect of lateral ankle ligament anesthesia on single-leg stance stability

PURPOSE

This study was designed to determine, in isolation, the contribution of lateral ankle ligament mechanoreceptors to postural stability during single leg static (eyes open, eyes closed) and landing tasks.

METHODS

Fourteen healthy subjects (nine males, five females) underwent two different treatment conditions (control, anesthesia) in a counterbalanced order (48-h interval). During the anesthetic treatment, lidocaine was injected into the anterior talofibular and calcaneofibular ligament (1.5 cc each) regions. Postural stability was measured using forceplate and kinematic variables. The average of each variable across multiple trials under each treatment for the three tasks was analyzed statistically.

RESULTS

Results of all statistical analyses failed to demonstrate significant alterations (P > 0.05) in postural control attributable to the treatment condition.

CONCLUSION

These results suggest that lateral ankle ligament mechanoreceptors either do not make a significant contribution to single leg stance stability, do not have a unique, irreplaceable role, or have a role that is too subtle to be detected given the measurement techniques used. Thus, the idea that single leg stability becomes altered after ankle joint injury because of proprioceptive disruption was not supported. This would suggest that reported postural control alterations in persons after repetitive ankle injury more likely occur as a result of alterations in mechanical stability, motor components, and/or central motor programming.

Effects of circumferential ankle pressure on ankle proprioception, stiffness, and postural stability: a preliminary investigation

STUDY DESIGN

Cross-sectional repeated-measures design.

OBJECTIVE

Determine the effects of circumferential ankle pressure (CAP) intervention on proprioceptive acuity, ankle stiffness, and postural stability.

BACKGROUND

The application of CAP using braces, taping, and adaptive shoes or military boots is widely used to address chronic ankle instability (CAI). An underlying assumption is that the CAP intervention might improve ankle stability through increased proprioceptive acuity and stiffness in the ankle. METHOD AND MEASURES: A convenience sample of 10 subjects was recruited from the local university community and categorized according to proprioceptive acuity (high, low) and ankle stability (normal, CAI). Proprioceptive acuity was measured when blindfolded subjects were asked to accurately reproduce a self-selected target ankle position before and after the application of CAP. Proprioceptive acuity was determined in 5 different ankle joint position sense tests: neutral, inversion, eversion, plantar flexion, and dorsiflexion. Joint position angles were recorded electromechanically using a potentiometer. Passive ankle stiffness was computed from the ratio of applied static moment versus angular displacement. Active ankle stiffness was determined from biomechanical analyses of ankle motion following a mediolateral perturbation. Postural stability was quantified from the center of pressure displacement in the mediolateral and the anteroposterior directions in unipedal stance. All measurements were recorded with and without CAP applied by a pediatric blood pressure cuff. Data were analyzed using a separate mixed-model analysis of variance (ANOVA) for each dependent variable. Post hoc comparison using Tukey's honestly significant difference (HSD) test was performed if significant interactions were obtained. Significance level was set at P<.05 for all analyses.

RESULTS

Significant group (high versus low proprioceptive acuity) x CAP interactions were identified for postural stability. Passive ankle stiffness was not increased by an application of CAP. Active ankle stiffness was significantly different between the high and low proprioceptive acuity groups and was not affected by an application of CAP. Significant group (normal versus CAI) x CAP interactions were observed for mediolateral center-of-pressure displacement with a main effect of group on neutral joint position sense.

CONCLUSIONS

Application of CAP increased proprioceptive acuity and demonstrated trends toward increased active stiffness in the ankle, hence improved postural stability. The effects tend to be limited to individuals with low proprioceptive acuity.

Performance in Static, Dynamic, and Clinical Tests of Postural Control in Individuals with Recurrent Ankle Sprains

Objective:

To evaluate postural control in individuals with recurrent ankle sprains with static, dynamic, and clinical balance tests and to examine the relationships between performances in each of these tests.

Design:

Postural control was evaluated with 3 different balance tests in individuals with and without recurrent ankle sprains.

Participants:

19 volunteers with recurrent ankle sprains and 19 uninjured control subjects.

Interventions:

None.

Setting:

University sports-medicine research laboratory.

Main Outcome Measures:

Total excursion of the center of pressure (COP) was calculated for the static and dynamic balance tests. Total reach distance was measured for the Star Excursion Balance Test.

Results:

Subjects with recurrent ankle sprains demonstrated significantly greater excursion of the COP in both the static and dynamic balance tests. Correlations between performances in all tests were very low.

Conclusions:

Recurrent ankle sprains might be associated with reduced postural control as demonstrated by decreased performance in static and dynamic balance tests.

Relationship between two proprioceptive measures and stiffness at the ankle

Previous research has investigated the role of proprioception and stiffness in the control of joint stability. However, to date, no research has been done on the relationship between proprioception and stiffness. Therefore, the purpose of this study was to determine the relationship between force sense, joint reposition sense, and stiffness at the ankle. A heterogeneous sample was obtained for this study; 20 of the 40 participants had a history of ankle sprains, and 13 of the 20 had been diagnosed by a physician (two mild ankle sprains, seven moderate sprains, four severe sprains). All subjects were asymptomatic and active at the time of the study. Active joint reposition sense was measured using a custom-built ankle goniometer, force sense was measured unilaterally and contralaterally with a load cell, and ankle muscle stiffness was measured via transient oscillation using a custom-built inversion-eversion cradle. We found no significant correlations between stiffness and joint reposition sense, with values of r ranging from 0.01 to 0.21. Significant correlations were found between stiffness and force sense. Specifically, contralateral force sense reproduction was significantly correlated to stiffness in the injured or "involved" ankle (r's ranging from 0.47 to 0.65; P< or =0.008). Whether the decreased ability to appropriately sense force (increased error) sends information to the central nervous system to increase muscle stiffness in response to an unexpected loss of stability, or whether these two phenomena function independently and both change concurrently as a result of injury to the system requires further investigation.

Assessing Functional Ankle Instability with Joint Position Sense, Time to Stabilization, and Electromyography

Context:

Functional ankle instability (FAI) is difficult to identify and quantify.

Objective:

To compare joint position sense (JPS), time to stabilization (TTS), and electromy-ography (EMG) of ankle musculature in recreational athletes with and without FAI.

Design:

Case-control compared withttests and ANOVAs.

Setting:

Sports medicine research laboratory.

Participants:

20 recreational athletes.

Main Outcome Measures:

Passive angle reproduction, TTS, and mean EMG amplitude of the tibialis anterior, peroneals, lateral gastrocnemius, and soleus muscles during single-leg-jump landing.

Results:

No differences in JPS or medial-lateral TTS measures between groups. Significantly longer anterior-posterior TTS (P< .05) in the unstable ankle group. The stable ankle group had significantly higher mean EMG soleus amplitude after landing (P< .05). No other significant differences were found for mean EMG amplitudes before or after landing.

Conclusions:

Subjects with FAI demonstrated deficits in landing stability and soleus muscle activity during landing that may represent chronic adaptive changes following injury.

Quantitative Assessment of Mechanical Laxity in the Functionally Unstable Ankle

PURPOSE

Delineating between functional and mechanical instability in those with chronic ankle dysfunction is a challenging task. Current methods of assessing ankle ligamentous laxity are subjective in nature and limit our ability to identify the site and extent of instability; therefore, a need exists for objective laxity measurements. The purpose of this study was to determine whether subjects with self-reported, functional ankle instability (FAI) demonstrated increased mechanical laxity when tested with instrumented arthrometry and stress radiography.

METHODS

Both ankles were tested in 51 subjects with self-reported unilateral FAI. An instrumented ankle arthrometer measured ankle-subtalar joint motion for total anteroposterior (AP) displacement (mm) during loading at 125 N and total inversion-eversion (I-E) rotation (degrees of ROM) during loading at 4 N x m. The Telos GA-II/E device provided either anterior or lateral stress (15 kp) while fluoroscopic radiographs were recorded for anterior displacement (mm) and talar tilt (degrees).

RESULTS

The arthrometry measurements of anterior and total AP displacement and the radiographic measurements of anterior displacement were greater (P < 0.05) in the FAI ankles when compared with the uninjured ankles. There were no differences in total I-E rotation, inversion rotation, or talar tilt between ankles when analyzed with either measurement technique.

CONCLUSION

The ability to objectively measure mechanical instability in the functionally unstable ankle is important to understanding the nature and cause of the instability. Ankle arthrometry and stress radiographic measurements are objective assessment tools for mechanical laxity. Despite finding greater laxity in the functionally unstable ankle, the clinical significance of the observed displacement remains unanswered. Further research is needed to determine the amount of laxity that constitutes mechanical instability and how this relates to FAI.

Risk factors for injuries in football

BACKGROUND

The injury risk in football is high, but little is known about causes of injury.

PURPOSE

To identify risk factors for football injuries using a multivariate model.

STUDY DESIGN

Prospective cohort study.

METHODS

Participants were 306 male football players from the two highest divisions in Iceland. Before the 1999 football season started, the following factors were examined: height, weight, body composition, flexibility, leg extension power, jump height, peak O(2) uptake, joint stability, and history of previous injury. Injuries and player exposure were recorded throughout the competitive season.

RESULTS

Older players were at higher risk of injury in general (odds ratio [OR] = 1.1 per year, P = 0.05). For hamstring strains, the significant risk factors were age (OR = 1.4 [1 year], P < 0.001) and previous hamstring strains (OR = 11.6, P <0.001). For groin strains, the predictor risk factors were previous groin strains (OR = 7.3, P = 0.001) and decreased range of motion in hip abduction (OR = 0.9 [1 degrees ], P = 0.05). Previous injury was also identified as a risk factor for knee (OR = 4.6) and ankle sprains (OR = 5.3).

CONCLUSIONS

Age and previous injury were identified as the main risk factors for injury among elite football players from Iceland.

Video analysis of the mechanisms for ankle injuries in football

BACKGROUND

Although ankle sprains are frequent in football, little is known about their mechanisms.

PURPOSE

To describe the injury mechanisms for ankle injuries in male elite football.

STUDY DESIGN

Prospective cohort study.

METHODS

Videotapes and injury information were collected for 313 of 409 matches from Norwegian and Icelandic elite football during the 1999 to 2000 seasons. Video recordings of incidents that resulted in ankle injuries were analyzed and cross-referenced with injury reports from the team medical staff.

RESULTS

A total 46 acute ankle injuries were reported to have occurred, that is, 4.5 injuries per 1000 match hours. Of these, 26 (57%) were identified on the videotapes. Two mechanisms thought to be specific to football were found: 1) player-to-player contact with impact by an opponent on the medial aspect of the leg just before or at foot strike, resulting in a laterally directed force causing the player to land with the ankle in a vulnerable, inverted position; and 2) forced plantar flexion where the injured player hit the opponent's foot when attempting to shoot or clear the ball.

CONCLUSIONS

Systematic video analysis provides detailed information on the mechanisms for ankle injuries in football-for lateral ligament sprains and for the condition dubbed "footballer's ankle."