Epidemiological study of post-traumatic ankle osteoarthritis after ankle sprain in 195,393 individuals over middle age using the National Health Insurance Database: A retrospective design.

OBJECTIVES: This study aimed to determine the risk of ankle OA onset after an incidence of sprain, relative to the risk of onset in healthy population, and to investigate the effect of gender, age, BMI, and exercise on the development of ankle OA after sprain. DESIGN: Retrospective cohort study. METHODS: Using a sample cohort dataset from 2002 to 2013 provided by the Korean National Health Insurance Sharing Service, we calculated the mean survival time and cumulative incidence rate in sprained and healthy populations using Kaplan-Meier analysis. A Cox proportional hazards model was used to analyze the adjusted hazard ratio (HR) of sprain for the development of OA with 95% confidence intervals (CIs). Adjusted HRs of gender, age, BMI, and exercise (yes/no) were analyzed in the sprained group. RESULTS: Among the selected population of 195,393 individuals, 40,876 (20.9%) were diagnosed with an ankle sprain, and 1543 (3.85%) of those individuals developed ankle OA. Of the 154,517 healthy individuals (79.1%), 4062 (2.66%) cases had progressed to OA. The sprained group had 46% (HR, 1.46; 95% CI, 1.38-1.55) greater rate of progression to ankle OA than did healthy individuals. In the sprain group, individuals who were female, obese, and overweight had 40% (HR, 1.40; 95% CI, 1.26-1.55), 43% (HR, 1.43; 95% CI, 1.12-1.82), and 22% (HR, 1.22; 95% CI, 1.10-1.35) higher incidence to develop ankle OA, respectively, compared to those who were male, underweight and normal. CONCLUSIONS: This study found that ankle sprain was a significant risk factor for a diagnosis of early OA. Female gender and high BMI increased the incidence of ankle OA after sprain.

Should ice application be replaced with neurocryostimulation for the treatment of acute lateral ankle sprains? A randomized clinical trial.

STUDY DESIGN: Single-blind parallel group randomized clinical trial. OBJECTIVES: To compare the effects of neurocryostimulation (NCS) with those of traditional ice application on functional recovery, pain, edema and ankle dorsiflexion range of motion (ROM) in individuals receiving physiotherapy treatments for acute lateral ankle sprains (LAS). BACKGROUND: Ankle sprain is a very common injury and its management is often costly, with important short- and long-term impacts on individuals and society. As new methods of therapy using cold (cryotherapy) are emerging for the treatment of musculoskeletal conditions, little evidence exists to support their use. NCS, which provokes a rapid cooling of the skin with the liberation of pressured CO2, is a method believed to accelerate the resorption of edema and recovery in the case of traumatic injuries. METHODS: Forty-one participants with acute LAS were randomly assigned either to a group that received in-clinic physiotherapy treatments and NCS (experimental NCS group, n = 20), or to a group that received the same in-clinic physiotherapy treatments and traditional ice application (comparison ice group, n = 21). Primary (Lower Extremity Functional Scale - LEFS) and secondary (visual analog scale for pain intensity at rest and during usual activities in the last 48 h, Figure of Eight measurement of edema, and weight bearing lunge for ankle dorsiflexion range of motion) outcomes were evaluated at baseline (T0), after one week (T1), two weeks (T2), four weeks (T4) and finally, after six weeks (T6). The effects of interventions were assessed using two-way ANOVA-type Nonparametric Analysis for Longitudinal Data (nparLD). RESULTS: No significant group-time interaction or group effect was observed for all outcomes (0.995 ≥ p ≥ 0.057) following the intervention. Large time effects were however observed for all outcomes (p <  0.0001). CONCLUSION: Results suggest that neurocryostimulation is no more effective than traditional ice application in improving functional recovery, pain, edema, and ankle dorsiflexion ROM during the first six weeks of physiotherapy treatments in individuals with acute LAS. LEVEL OF EVIDENCE: Therapy, level 1b. TRIAL REGISTRATION: ClinicalTrials.gov , NCT02945618 . Registered 23 October 2016 - Retrospectively registered (25 participants recruited prior to registration, 17 participants after).

Sport injury prevention in individuals with chronic ankle instability: Fascial Manipulation® versus control group: A randomized controlled trial.

Chronic ankle instability (CAI) is one of the most common syndromes that occurs following an initial ankle sprain. Sprains are often correlated with recurrent sprains, loss of range of motion (ROM) and deficits in proprioception and postural control. The objectives were to evaluate the effectiveness of Fascial Manipulation® (FM) as a preventative measure in semi-professional athletes with CAI, and to monitor the symptomatology, equilibrium and ROM of the injured ankle. A single-blinded randomized controlled trial was conducted in the rehabilitation department of a medical centre. Twenty-nine semi-professional male footballers were recruited. Nine subjects with no previous symptomatology, were assigned to a baseline group, twenty symptomatic subjects were randomized into either the study or the control group. All three groups followed a specific training program. The control group followed normal training protocols and received standard medical care. The study group received an additional three FM treatment sessions. Symptomatology and ROM outcomes were recorded for all players at baseline, before each treatment for the treatment group, and at 1-, 3-, and 6-month follow-ups. At one year, an additional follow-up on was performed via phone. Four severe ankle traumas and one mild ankle trauma were reported in the control group during the trial period. The 6-month outcomes in the study group showed statistically significant improvements. The 1-year follow-up reported the absence of any reported trauma in the study group. FM was effective in improving ROM and symptomatology in footballers with CAI. FM intervention was effective in preventing injury in the study sample.

Leg massage by mother resulting in fatal pulmonary thromboembolism.

We report the sudden death of a 23-year-old male with hairline ankle fracture after massage of the leg by his mother. Autopsy confirmed the cause of death as pulmonary thromboembolism due to deep vein thrombosis of the leg veins which was dislodged and travelled to his lungs consequent to the leg massage. The treating doctors did not warn the patient of the risk of developing pulmonary thromboembolism.

The immediate effect of talocrural joint manipulation on functional performance of 15-40 years old athletes with chronic ankle instability: A double-blind randomized clinical trial.

OBJECTIVE: To evaluate the immediate effect of talocrural joint manipulation (TCJM) on functional performance of athletes with chronic ankle instability (CAI). PARTICIPANTS: Forty athletes (18males, 22females) with CAI divided into TCJM group (n = 20) and sham manipulation group (n = 20). INTERVENTION: TCJM was performed as a quick thrust on the involved talus, in the posterior direction. Sham manipulation was maintaining the same position, without any thrust. MAIN OUTCOME MEASURES: Functional performance of athletes was assessed with single leg hop; speed and Y balance tests, before and after the interventions. RESULTS: All functional tests evaluated in this study improved significantly after TCJM (p-value<0.05). These findings were not seen in the control group. Between-group comparisons also showed significant changes for all the measurements after the interventions (p < 0.05). CONCLUSIONS: TCJM can significantly increase the functional performance of athletes with CIA and can be an effective supplementary treatment for these subjects. However, this was a pre-post study and future studies with long-term follow-ups may provide more reliable results about the long-term effectiveness of this type of treatment.

Comparative Effectiveness of Plantar-Massage Techniques on Postural Control in Those With Chronic Ankle Instability.

CONTEXT: One of the major concerns after an acute lateral ankle sprain is the potential for development of chronic ankle instability (CAI). The existing research has determined that clinician-delivered plantar massage improves postural control in those with CAI. However, the effectiveness of self-administered treatments and the underlying cause of any improvements remain unclear. OBJECTIVES: To determine (1) the effectiveness of a self-administered plantar-massage treatment in those with CAI and (2) whether the postural-control improvements were due to the stimulation of the plantar cutaneous receptors. DESIGN: Crossover study. SETTING: University setting. PATIENTS OR OTHER PARTICIPANTS: A total of 20 physically active individuals (6 men and 14 women) with self-reported CAI. INTERVENTION(S): All participants completed 3 test sessions involving 3 treatments: a clinician-delivered manual plantar massage, a patient-delivered self-massage with a ball, and a clinician-delivered sensory brush massage. MAIN OUTCOME MEASURE(S): Postural control was assessed using single-legged balance with eyes open and the Star Excursion Balance Test. RESULTS: Static postural control improved (P ≤ .014) after each of the interventions. However, no changes in dynamic postural control after any of the interventions were observed (P > .05). No differences were observed between a clinician-delivered manual plantar massage and either a patient-delivered self-massage with a ball or a clinician-delivered sensory brush massage in any postural-control outcome. CONCLUSIONS: In those with CAI, single 5-minute sessions of traditional plantar massage, self-administered massage, and sensory brush massage each resulted in comparable static postural-control improvements. The results also provide empirical evidence suggesting that the mechanism for the postural-control improvements is the stimulation of the plantar cutaneous receptors.

Osseous Healing in Foot and Ankle Surgery with Autograft, Allograft, and Other Orthobiologics.

In the surgical treatment of foot and ankle abnormality, many problems require bone grafting for successful osseous union. Nonunion, reconstruction, and arthrodesis procedures pose specific challenges due to bony defects secondary to trauma, malunions, or previous surgery. Nonunion in foot and ankle arthrodesis is a significant risk and is well documented in recent literature. This article is a review of the recent literature regarding the use of bone graft and orthobiologics in foot and ankle surgery.

Chronic complaints after ankle sprains: a systematic review on effectiveness of treatments.

STUDY DESIGN: Systematic review. Objective To determine the effectiveness of treatments for patients with chronic complaints after ankle sprain. BACKGROUND: Though most people recover completely after a lateral inversion ankle injury, a considerable percentage have persistent complaints. Currently, it is still unclear which treatment options are best for these patients. METHODS: Major databases, including PubMed, Embase, CINAHL, and PEDro, were searched for randomized controlled trials and controlled clinical trials conducted from 1966 to October 2012. Due to clinical heterogeneity, the data were analyzed using a best-evidence synthesis. RESULTS: A total of 20 randomized controlled trials and 1 controlled clinical trial were included in the analysis. The included studies compared different treatments (training programs, physiotherapy, chiropractic/manual therapy, surgery, postoperative training, and functional treatment). For pain and function outcomes, limited to moderate evidence was found for effectiveness of a training program compared to conservative treatment. Two studies found a decrease of recurrences after a proprioceptive training program. Four studies showed good results for different surgical methods but did not include a nonsurgical control group for comparison. Limited evidence was found for the effectiveness of an early mobilization program after surgery. CONCLUSION: In chronic ankle complaints after an ankle sprain, a training program gives better results for pain and function, and a decrease of recurrent ankle sprains, than a wait-and-see policy. There was insufficient evidence to determine the most effective surgical treatment, but limited evidence suggests that postoperative, early mobilization was more effective than a plaster cast. LEVEL OF EVIDENCE: Therapy, level 1a-.

[Clinical observation of traumatic ankle arthritis with orthopedics lotion on 60 cases].

Observing the clinical curative effect of orthopedics lotion to treat traumatic ankle arthritis, the outpatient department of orthopedics in Guang'anmen Hospital collected 60 cases who were diagnosed as traumatic ankle arthritis. The cases who already met the inclusion criteria, were randomly divided into the treatment group (30 cases) and control group (30 cases). Thirty patients in treatment group were received fumigation treatment with orthopedics lotion; 30 patients in control group were treated by intra-articular injection of sodium hyaluronate. After 5 weeks treatment, the effects on the both groups would be observed and analysed. Baird-Jackson scoring system was used to assess the overall curative effect. Visual analogue scales (VAS) was used to assess analgesic effect. BJ scores of pre-treatment and post-treatment in both the treatment group and the control group were compared, P <0O. 01, significantly different; and the BJ scores after treatment of two groups were compared by paired t-test, the t value is 1. 76, there was no significant difference between two groups. Both of the treatments were effective, but there was no significant difference in overall curative effect between the two kinds of treatment. The VAS scores after treatment of two groups were compared by paired t-test, the t value was 2. 282, and there was a significant difference between two groups (P <0. 05). The analgesic effect shown in treatment group was better than the control group. The results suggest that: orthopedics lotion is a effective way to treat traumatic ankle arthritis, and it has significant effect on analgesic.

Acupuncture as analgesia for non-emergent acute non-specific neck pain, ankle sprain and primary headache in an emergency department setting: a protocol for a parallel group, randomised, controlled pilot trial.

INTRODUCTION: This study aims to assess the feasibility of acupuncture as an add-on intervention for patients with non-emergent acute musculoskeletal pain and primary headache in an emergency department (ED) setting. METHODS AND ANALYSIS: A total of 40 patients who present to the ED and are diagnosed to have acute non-specific neck pain, ankle sprain or primary headache will be recruited by ED physicians. An intravenous or intramuscular injection of analgesics will be provided as the initial standard pain control intervention for all patients. Patients who still have moderate to severe pain after the 30 min of initial standard ED management will be considered eligible. These patients will be allocated in equal proportions to acupuncture plus standard ED management or to standard ED management alone based on computer-generated random numbers concealed in opaque, sealed, sequentially numbered envelopes. A 30 min session of acupuncture treatment with manual and/or electrical stimulation will be provided by qualified Korean medicine doctors. All patients will receive additional ED management at the ED physician's discretion and based on each patient's response to the allocated intervention. The primary outcome will be pain reduction measured at discharge from the ED by an unblinded assessor. Adverse events in both groups will be documented. Other outcomes will include the patient-reported overall improvement, disability due to neck pain (only for neck-pain patients), the treatment response rate, the use of other healthcare resources and the patients' perceived effectiveness of the acupuncture treatment. A follow-up telephone interview will be conducted by a blinded assessor 72±12 h after ED discharge. ETHICS AND DISSEMINATION: Written informed consent will be obtained from all participants. The study has been approved by the Institutional Review Boards (IRBs). The results of this study will guide a full-scale randomised trial of acupuncture in an ED context. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov: NCT02013908.

Efficacy and safety of high-dose vitamin C on complex regional pain syndrome in extremity trauma and surgery--systematic review and meta-analysis.

Complex regional pain syndrome (CRPS) is a devastating condition often seen after foot and ankle injury and surgery. Prevention of this pathology is attractive not only to patients but also to surgeons, because the treatment of this condition can be difficult. We evaluated the effectiveness of vitamin C in preventing occurrence of CRPS in extremity trauma and surgery by systematically reviewing relevant studies. The databases used for this review included: Ovid EMBASE, Ovid MEDLINE, CINAHL, and the Cochrane Database. We searched for comparative studies that evaluated the efficacy of more than 500 mg of daily vitamin C. After screening for inclusion and exclusion criteria, we identified 4 studies that were relevant to our study question. Only 1 of these 4 studies was on foot and ankle surgery; the rest concerned the upper extremities. All 4 studies were in favor of this intervention with minimal heterogeneity (Tau(2) = 0.00). Our quantitative synthesis showed a relative risk of 0.22 (95% confidence interval = 0.12, 0.39) when daily vitamin C of at least 500 mg was initiated immediately after the extremity surgery or injury and continued for 45 to 50 days. A routine, daily administration of vitamin C may be beneficial in foot and ankle surgery or injury to avoid CRPS. Further foot and ankle specific and dose-response studies are warranted.

Joint mobilization acutely improves landing kinematics in chronic ankle instability.

PURPOSE: The objective of this study is to examine the acute effect of ankle joint mobilizations akin to those performed in everyday clinical practice on sagittal plane ankle joint kinematics during a single-leg drop landing in participants with chronic ankle instability (CAI). METHODS: Fifteen participants with self-reported CAI (defined as <24 on the Cumberland Ankle Instability Tool) performed three single-leg drop landings under two different conditions: 1) premobilization and, 2) immediately, postmobilization. The mobilizations performed included Mulligan talocrural joint dorsiflexion mobilization with movement, Mulligan inferior tibiofibular joint mobilization, and Maitland anteroposterior talocrural joint mobilization. Three CODA cx1 units (Charnwood Dynamics Ltd., Leicestershire, UK) were used to provide information on ankle joint sagittal plane angular displacement. The dependent variable under investigation was the angle of ankle joint plantarflexion at the point of initial contact during the drop landing. RESULTS: There was a statistically significant acute decrease in the angle of ankle joint plantarflexion from premobilization (34.89° ± 4.18°) to postmobilization (31.90° ± 5.89°), t(14) = 2.62, P < 0.05 (two-tailed). The mean decrease in the angle of ankle joint plantarflexion as a result of the ankle joint mobilization was 2.98° with a 95% confidence interval ranging from 0.54 to 5.43. The eta squared statistic (0.32) indicated a large effect size. CONCLUSION: These results indicate that mobilization acted to acutely reduce the angle of ankle joint plantarflexion at initial contact during a single-leg drop landing. Mobilization applied to participants with CAI has a mechanical effect on the ankle joint, thus facilitating a more favorable positioning of the ankle joint when landing from a jump.

Manejo del paciente hemipléjico mediante la utilización de AFOs: puntos clave para la prescripción podológica de Afos / Managemente of the hemiplegic patient by applying AFO. Key points when prescribing AFO

El propósito de este trabajo es revisar los últimos estudios realizados sobre el uso de ayudas ortésicas en el tratamiento de pacientes hemipléjicos, y establecer unos criterios para determinar los usos de los diferentes modelos de ortesis. Las opciones disponibles son muchas y carecemos de datos a este respecto en la bibliografía, son pocas las publicaciones con evidencia científica que han medido la efectividad de dichas ortesis. Por los antecedentes, en el año 2003 se organiza la Conferencia de Consenso Internacional sobre el tratamiento ortésico de los pacientes con Ictus y se intenta unificar criterios. De manera general, el objetivo perseguido con el uso de las ortesis en pacientes hemipléjicos es el mantenimiento de la posición adecuada de los pies para obtener una marcha más funcional. Según los últimos estudios realizados al respecto en niños hemipléjicos, los AFOs articulados parecen ser más efectivos que los AFOs rígidos, por la aproximación biomecánica que pretenden ofrecer con respecto al movimiento normal del tobillo (AU)

The purpose of this work is to revise the latest studies on the use of orthotic devices when treating hemiplegic patients, and to establish criteria to determine the use of different models. There are many existing alternatives however there is a lack of bibliography. There are fexw publications with scientific evidence that have measured the effectiveness of those orthoses. In 2003, the International Consensus Conference on orthotic treatments on patients with ictus tried to unify criteria. In general, the main purpose of the orthoses applied to hemiplegic people is to maintain the adequate position of their feet in order to have a more functional gait. According to the most recent studies on hemiplegic children, the articulated AFO seems to be more effective than the rigid AFO, due to its biomechanical effect (AU)

Electroacupuncture analgesia in rat ankle sprain pain model: neural mechanisms.

OBJECTIVES: Acupuncture, an alternative medical therapy with a long history, is appealing because it can activate endogenous analgesic mechanisms by minimally invasive means. The mechanisms of acupuncture, however, are not well understood yet. The following sentence was removed from our original manuscript. One of the major problems impeding understanding of the acupuncture mechanism is lack of experimental models that mimic various forms of persistent pain that respond to acupuncture in humans. METHODS: In this review, we summarize and discuss previous and recent findings regarding electroacupuncture-induced analgesia in an ankle sprain pain model and the potential underlying mechanisms of acupuncture. RESULTS: A novel model of ankle sprain pain is introduced recently and the mechanism of electroacupuncture-induced analgesia in this model has been explored. The following sentence was removed from our original manuscript. This model provides a reproducible and quantifiable index of persistent pain at the ankle joint in rats. Acupuncture at a remote site produces long-lasting and powerful analgesia. The consistent analgesic effect of acupuncture in this model has allowed us to pursue the underlying neural mechanisms. CONCLUSIONS: These studies provide insight into the mechanisms of acupuncture analgesia in one particular form of persistent pain, and hopefully will allow us to expand our knowledge to other painful conditions.

Electroacupuncture-induced analgesia in a rat model of ankle sprain pain is mediated by spinal alpha-adrenoceptors.

In a previous study, we showed that electroacupuncture (EA) applied to the SI-6 point on the contralateral forelimb produces long-lasting and powerful analgesia in pain caused by ankle sprain in a rat model. To investigate the underlying mechanism of EA analgesia, the present study tested the effects of various antagonists on known endogenous analgesic systems in this model. Ankle sprain was induced in anesthetized rats by overextending their right ankle with repeated forceful plantar flexion and inversion of the foot. When rats developed pain behaviors (a reduction in weight-bearing of the affected hind limb), EA was applied to the SI-6 point on the contralateral forelimb for 30 min under halothane anesthesia. EA significantly improved the weight-bearing capacity of the affected hind limb for 2h, suggesting an analgesic effect. The alpha-adrenoceptor antagonist phentolamine (2mg/kg, i.p. or 30 microg, i.t.) completely blocked the EA-induced analgesia, whereas naloxone (1mg/kg, i.p.) failed to block the effect. These results suggest that EA-induced analgesia is mediated by alpha-adrenoceptor mechanisms. Further experiments showed that intrathecal administration of yohimbine, an alpha(2)-adrenergic antagonist, reduced the EA-induced analgesia in a dose-dependent manner, whereas terazosin, an alpha(1)-adrenergic antagonist, did not produce any effect. These data suggest that the analgesic effect of EA in ankle sprain pain is, at least in part, mediated by spinal alpha(2)-adrenoceptor mechanisms.

The effect of 2 Hz and 100 Hz electrical stimulation of acupoint on ankle sprain in rats.

The electrical stimulation of acupoint (ESA) releases several endogenous neuropeptides, which play important roles in management of pain and inflammation. ESA with low and high frequencies has been shown to release different neuropepides, suggesting its various therapeutic effects. Pain and edema are major problems for ankle sprain. However, there have been few reports on the effects of ESA for ankle sprain. We aimed to investigate that ESA can reduce pain and edema resulting from ankle sprain, and whether there is a difference in therapeutic effects between low and high frequency ESA. To induce ankle sprain in Sprague-Dawley rats, the ankle of right hindpaw was overextended in direction of simultaneous inversion and plantar flexion. Stepping force and edema in the paw of the sprained ankle were measured by electronic balance and plethysmometer, respectively. In both 2 and 100 Hz ESA groups, stepping force was increased significantly in similar degrees (p<0.05). Only 2 Hz ESA produced the significant rapid decrease in ankle edema. This study demonstrates that ESA of 2 Hz and 100 Hz shows comparable analgesic effects, but only 2 Hz ESA can facilitate the reduction of edema caused by ankle sprain.

The Effect of 2 Hz and 100 Hz Electrical Stimulation of Acupoint on Ankle Sprain in Rats

The electrical stimulation of acupoint (ESA) releases several endogenous neuropeptides, which play important roles in management of pain and inflammation. ESA with low and high frequencies has been shown to release different neuropepides, suggesting its various therapeutic effects. Pain and edema are major problems for ankle sprain. However, there have been few reports on the effects of ESA for ankle sprain. We aimed to investigate that ESA can reduce pain and edema resulting from ankle sprain, and whether there is a difference in therapeutic effects between low and high frequency ESA. To induce ankle sprain in Sprague-Dawley rats, the ankle of right hindpaw was overextended in direction of simultaneous inversion and plantar flexion. Stepping force and edema in the paw of the sprained ankle were measured by electronic balance and plethysmometer, respectively. In both 2 and 100 Hz ESA groups, stepping force was increased significantly in similar degrees (p<0.05). Only 2 Hz ESA produced the significant rapid decrease in ankle edema. This study demonstrates that ESA of 2 Hz and 100 Hz shows comparable analgesic effects, but only 2 Hz ESA can facilitate the reduction of edema caused by ankle sprain.

Low-level laser treatment can reduce edema in second degree ankle sprains.

OBJECTIVE: Low-level laser therapy (LLLT) has been used for the last few years to treat sports injuries. The purpose of this study was to compare three therapeutic protocols in treating edema in second degree ankle sprains that did not require immobilization with a splint, under placebo-controlled conditions. MATERIALS AND METHODS: Forty-seven soccer players with second degree ankle sprains, selected at random, were divided into the following groups: The first group (n = 16) was treated with the conventional initial treatment (RICE, rest, ice, compression, elevation), the second group (n = 16) was treated with the RICE method plus placebo laser, and the third group (n = 15) was treated with the RICE method plus an 820-nm GaA1As diode laser with a radiant power output of 40 mW at 16 Hz. Before the treatment, and 24, 48, and 72 h later, the volume of the edema was measured. RESULTS: A three by three repeated measures ANOVA with a follow up post hoc test revealed that the group treated with the RICE and an 820-nm GaA1As diode laser presented a statistically significant reduction in the volume of the edema after 24 h (40.3 +/- 2.4 mL, p < 0.01), 48 h (56.4 +/- 3.1 mL, p < 0.002), and 72 h (65.1 +/- 4.4 mL, p < 0.001). CONCLUSIONS: LLLT combined with RICE can reduce edema in second-degree ankle sprains.

Effect of anesthesia of the sinus tarsi on peroneal reaction time in patients with functional instability of the ankle.

We investigated peroneal reaction time (PRT) of 18 patients (21 ankles) with functional instability of the ankle and 8 healthy volunteer controls (9 ankles) before and after injecting local anesthetic into the sinus tarsi. The median PRT in patients before the injection was 82.0 ms, a significant delay from 71.0 ms in controls. After the injection, PRT in controls did not change, but PRT in patients significantly shortened to 69.3 ms. The sense of instability and the functional instability improved simultaneously. A disorder of the gamma-muscle-spindle system, induced by proprioceptive deficit after damage to a ligament, has been advocated as a cause of prolonged PRT. We suggest that irritability of mechanoreceptors or nociceptors or both, induced by inflammation at the sinus tarsi, may suppress the activities of gamma motor neurons of peroneal muscles, which in turn might cause the symptoms of functional instability and prolonged PRT.