Abstract
Keywords
Objectives
Define proprioception and its role in ankle stability.
Explain the types and functions of proprioceptors involved in ankle stability and postural control.
Analyze factors affecting ankle proprioception, including injury, age, and sensory feedback.
Review assessment techniques for evaluating proprioception in the ankle.
Discuss effective interventions to enhance ankle proprioception and improve ankle stability.
Introduction
Sir Charles Sherrington, who introduced the term in 1906, defined proprioception as a reflex system for maintaining body position, coordinating movement, and providing awareness of body position. 14 His work on the topic earned him the 1932 Nobel Prize in Physiology or Medicine. Proprioception is the sense of body position, movement, and spatial orientation, involving both conscious and unconscious components. It is crucial in determining the body’s relationship with its environment.5,80,81 This complex sensory system integrates information from various mechanoreceptors located in muscles, joints, tendons, and fascia throughout the body.52,78 It works with other sensory systems, such as vision and the vestibular system, to comprehensively understand body position, velocity, and acceleration. 79 The understanding of the body’s status in the world, combined with a visual reconstruction of the outside world and cognition, plays a crucial role in motor control, psychological functioning, activities of daily living, exercise, and sports.10,12,37,80
The current review focuses on the mechanisms of proprioception in maintaining ankle stability, the assessment of proprioception in the context of ankle instability, and effective therapeutic interventions for those with functional ankle instability.
Clinical Relevance
Ankle sprains are extremely common musculoskeletal injuries. They account for 20% to 40% of all sports-related injuries and represent 21% of all joint injuries in the body.13,74 Each year, an estimated 1 million people seek medical attention for acute ankle injuries. 66 Studies have indicated that chronic ankle instability can occur as a long-term effect of an ankle sprain, with reported rates ranging from 7% to 53%. 59
Proprioception plays a crucial role in maintaining dynamic ankle function and stability. Mechanoreceptors around the ankle contribute to postural balance and reflexive muscle responses by providing proprioceptive feedback to the central nervous system, which is vital for conscious and unconscious awareness of joint or limb motion. These enhance functional joint stability and are crucial in maintaining posture and balance.21,55,84 Proprioception deficits may contribute to recurrent ankle instability, osteochondral lesions, ankle arthritis, and diminished balance and postural control.
Basic Science
Ankle proprioception is facilitated by peripheral proprioceptors in various tissues, including skin, muscles, tendons, fascia, joint capsules, and ligaments. These tissues contain mechanoreceptors, specialized cells that transform mechanical stimuli, such as tissue stretch, into electrical stimuli in the form of action potentials. The ankle contains several proprioceptors, including muscle spindles, Golgi tendon organs, Ruffini corpuscles, Pacinian corpuscles, and free nerve endings (Table 1).42,86,91
Proprioceptors of the Ankle.
Muscle spindles are proprioceptors commonly found in most skeletal muscles throughout the body and play crucial roles in sensing muscle length, tension, and movement. This is important for determining joint position and balance control. 71 Ruffini corpuscles are believed to contribute mainly to maintaining muscle tone by sensing stretch and pressure. 91 They are found in the fibrous layer of joint capsules and ligaments and come in different types. 31 They can be found on both the medial and lateral ankle complexes, including the anterior talofibular ligament (ATFL), posterior talofibular ligament (PTFL), and calcaneofibular ligament (CFL). 86
Pacinian corpuscles are particularly sensitive to vibration and rapid changes in pressure, contributing to the perception of movement and touch.62,91 They are typically located within the fibrous tissue near capsular insertions.30,31 Pacinian corpuscles are the predominant type of mechanoreceptor in the ankle collateral ligaments. 86 This suggests that the main function of these ligaments is to sense joint speeds during motion.
Golgi tendon organs are primarily responsible for detecting changes in muscle tension and play a crucial role in regulating muscle contraction via an inhibitory effect on nearby motor units. They are located at the origins or insertion of a tendon, and rarely within a tendon. Free nerve endings are nociceptors that detect pain and potentially harmful stimuli. 64 In the lateral ankle ligaments, including the ATFL, PTFL, and CFLs, free nerve endings have been identified alongside other mechanoreceptors. 64
The signal from these receptors is processed and integrated in the central nervous system along with contributions from the vision and vestibular systems (Figure 1). Moreover, the complexity is further increased by the existence of 2 distinct proprioceptive pathways: conscious proprioception and unconscious proprioception. Unconscious proprioception is transmitted to the cerebellum via the spinocerebellar tracts, whereas conscious proprioception is transmitted to the thalamus and cerebral cortex by the dorsal column–medial lemniscus pathway. Following signal processing, in the central nervous system, the descending motor pathways regulate motor function.
Proprioception pathway for conscious proprioception. Note that unconscious proprioception is communicated to the cerebellum via the dorsal spinocerebellar tract and the ventral spinocerebellar tract.
Factors Affecting Ankle Proprioception
Injury and Instability
The interaction between ankle proprioception, injury, and instability is complex. The ongoing debate about ankle instability centers on whether individuals have impaired proprioception before sustaining an injury or if proprioceptive deficits develop as a consequence of the injury. Although some studies suggest that preexisting proprioceptive deficits may predispose individuals to ankle injuries, 85 others have shown that proprioceptive deficits develop postinjury, suggesting that injury to mechanoreceptors could be the primary cause. 20
Individuals with ankle instability often demonstrate deficits in peak isometric contraction, dynamic balance, proprioception, and maximum joint angles. 53 In patients with chronic ankle instability, there is a decrease in position awareness and prolonged reaction time of the peroneal muscles. 56 Similarly, Alex et al 3 demonstrated that individuals with functional ankle instability demonstrate poorer passive reposition sense and static balance ability compared to their healthy counterparts. Docherty et al 20 reported a positive relationship between force sense deficits and functional ankle instability. Witchalls et al 85 observed that individuals with ankle instability performed worse in differentiating inversion angles during proprioceptive tests. Even after therapy for ankle instability, studies have shown that acute trauma causes damage to proprioception, which is not fully restored by rehabilitation alone.24,25
Other studies bring a direct relationship between instability and proprioceptive deficits into question. de Noronha et al 16 found little to no relationship between proprioception and functional ankle instability, suggesting that by 1 month after an ankle sprain, loss of proprioception does not significantly contribute to instability. Miyachi et al reported no significant difference in ankle joint proprioception between individuals with chronic ankle instability and healthy controls. However, differences were observed in ankle dorsiflexion during dynamic balance tasks. 63 Pourkazemi et al 70 also reported no correlation between perceived ankle instability and proprioception measures such as joint position sense and movement detection sense. Kim et al 45 investigated the correlations between joint position sense and force sense in subjects with healthy ankles and those with functional ankle instability. They found no significant correlations between joint position sense and force sense in the functional ankle instability group.
Although not concerning the ankle, Lubiatowski et al 60 reported that unilateral shoulder instability affected proprioception in both shoulders, with an increased error of active reproduction of joint position in both the unstable and contralateral unaffected shoulders compared with a control group. This finding suggests that proprioceptive deficits can extend beyond the injured joint, potentially affecting the entire sensorimotor system. Although not exhaustively studied, at least one similar study has been performed on the ankle but with contradictory findings. Lim and Tan 58 suggest that proprioceptive deficits may not be present in all cases of functional ankle instability, as they found no difference in joint position sense and motion sense between injured and uninvolved ankles in subjects with unilateral functional ankle instability.
In summary, research on the impact of ankle injury and instability on proprioception is varied. Some studies indicate proprioceptive deficits in those with ankle instability, showing diminished position awareness, delayed peroneal muscle reaction, and impaired passive reposition sense in chronic cases. However, other studies suggest that proprioceptive deficits are not always present in functional ankle instability, indicating a complex and not fully understood relationship.
Age
Several studies indicate that aspects of ankle proprioception decline with age. Ko et al 48 showed that older adults had higher thresholds for perceiving ankle movement compared with younger adults. Impaired ankle proprioception in older adults has clinical effects other than just as measured at the ankle level as it is associated with balance problems, gait disorders, and increased fall risk.26,27,48,83 Westlake and Culham 83 found that threshold to perception of passive movement and passive joint position sense were higher in older adults compared with younger adults, indicating reduced proprioceptive acuity with age. Deshpande et al 17 suggest a graded relationship between ankle proprioceptive acuity and measures of balance, mobility, and physical function across the adult life span. This study showed that patients with ankle proprioception thresholds above certain levels consistently demonstrated poor balance, physical function, and mobility. Specifically, participants with a threshold for perception of passive movement >2.2 degrees consistently showed poor performance across various outcome measures. However, for more challenging tasks like single-leg stance, fastest walking speed, and short physical performance battery, even those with >1.4 degrees exhibited significantly worse performance. 17
Although it is generally accepted that proprioception deteriorates with age and is associated with decline in physical function, some studies support that in otherwise healthy adults, there is a limited difference in proprioception stratified by age. Djajadikarta et al 18 found no significant effect of age on ankle proprioceptive acuity in healthy community-dwelling adults when tested. Another study of physically active adults found that most middle-aged and older participants had ankle position sense thresholds within the range of young adults. However, some age-related differences emerged for small ankle displacements. 76 Finally, Franco et al 23 showed that active elderly adults maintained similar joint position sense and force perception at the ankle compared with young adults, although plantar cutaneous sensitivity declined.
These studies highlight the fact that although many studies show that measures of proprioception deteriorate with age, it may not be as much of a factor in healthy and physically active patients.
Sensory feedback, immobilization, and ankle bracing
Sensory feedback is crucial in ankle proprioception, influencing joint position sense and overall balance control. Input from various regions of the foot, including the plantar and dorsal skin, can significantly impact ankle joint proprioception. 62 This interplay between tactile feedback and proprioceptive signals from the foot and ankle contributes to improved joint position sense.
Complete immobilization, such as casting, has significant adverse effects on proprioception and the associated sensorimotor functions. Disuse from immobilization strongly disrupts the central nervous system’s ability to integrate sensory information properly, resulting in difficulties with motor behavior that, in turn, cause a functionally maladaptive cortical reorganization. 72 For example, Langer et al 50 noted that after just 16 days of cast or sling immobilization of the arm, patients had reduced brain cortical thickness of the associated motor and somatosensory area and a decrease in fractional anisotropy in the corticospinal tracts on magnetic resonance imaging as well as reduced performance on a motor skills examination. These changes indicate a rapid reorganization of the sensorimotor system and highlight how immobilization can induce neurologic adaptations, potentially impacting proprioception. 50 This disruption is further complicated by the sensorimotor integration process, which is crucial for achieving skilled movement. Sensorimotor integration depends on the interaction between sensory and motor systems, and when any part of this network is impaired, learning and executing movements become challenging. 7 This impairment can lead to proprioceptive deficits, which in turn affect balance and increase fall risk, especially in older adults.
Ankle immobilization via bracing or taping may enhance proprioception in certain conditions, likely because of increased cutaneous feedback from the motion restraint provided by the brace or tape. Heit et al 35 found that both bracing and taping significantly improved joint position sense for plantar flexion compared with no support, with taping also enhancing inversion sense. Feuerbach et al 22 reported that rigid ankle orthoses significantly reduced errors in matching reference ankle positions. However, these studies primarily focused on stable ankles or healthy subjects. The effects may differ in injured ankles or those with chronic instability. Xue et al 87 noted that although external support showed some positive effects on active joint position sense in patients with chronic ankle instability, the changes were clinically small, and previous studies have been of poor quality. Combining treatments, with the use of kinesiology tape in combination with balance training on a wobble board, showed significant improvements in postural stability, balance, and ankle stability among female athletes with ankle instability. 43
Physical Examination
Assessment Techniques
Several assessment techniques may be used to evaluate proprioceptive deficits in the ankle. It is important to note that while these assessment techniques are commonly referred to as “proprioceptive tests,” some may actually measure broader aspects of sensorimotor control rather than isolated proprioception. 9 Clinicians should carefully consider the specific deficits they aim to assess when selecting an appropriate test.
Joint position sense tests, which measure a person’s ability to reproduce a passively positioned joint angle with active control, are commonly used and have moderate evidence supporting their validity and reliability.9,67 These tests typically involve actively or passively positioning the ankle at specific angles and then asking subjects to reproduce or identify those angles. They can be performed in plantarflexion, dorsiflexion, inversion, and eversion.
Stance relies on the sensory inputs including vision, vestibular input, and proprioception. The modified Romberg test is used to test proprioception and isolate visual contribution by having subjects balance on one foot with eyes open and then closed. 8 The examiner measures the time the subject can maintain balance, with a standard of 20 seconds considered normal for adults.1,36 This test can detect differences between injured and uninjured ankles. Interestingly, while the modified Romberg test was originally designed to assess proprioception, recent research suggests that performing the test on a soft (rather than a firm) surface with eyes closed may be more indicative of vestibular function than proprioception. 32 This highlights the complex interplay between different sensory systems in maintaining balance.
Force matching tests may also be employed. Subjects attempt to reproduce a target force at the ankle joint. 45 This also assesses force sense, another component of proprioception, and can be performed by applying a known force to the foot (or partial weight bearing on the extremity), and then having the patient reproduce that same force level. This combines force sense with motor control.
Threshold for detection of passive movement is another test, where the minimum angle of passive ankle rotation that can be detected by a subject is determined.18,90 This assesses the sensitivity to movement.
Motion sense acuity is evaluated by having subjects discriminate between different velocities of passive ankle rotation.38,90 The just-noticeable-difference in velocity serves as a measure of motion sense.
The star excursion balance test (SEBT) evaluates single-leg balance and dynamic neuromuscular control, requiring a combination of strength, flexibility, and proprioceptive abilities. 15 It is performed by having the patient stand on one leg and reach maximally with the contralateral leg in defined directions, forming an 8-point star shape. The SEBT has been shown to have excellent intraobserver reliability and is a sensitive test for ankle instability.47,75
There are other methods described in the literature using specific devices. These include an instrumented version of the SEBT, the Active Movement Extent Discrimination Apparatus (AMEDA) in the case of stroke survivors, or the Ankle Inversion Discrimination Apparatus for Landing (AIDAL), which may be of use for task-specific contexts.34,68,82
Standardized Testing Importance
Standardized testing is important for assessing ankle proprioception after an ankle instability episode. Following an ankle injury, patients may experience improvements in clinical symptoms such as pain and swelling. However, proprioceptive deficits can persist even after these visible signs of injury have subsided (see Figure 2). Testing allows for consistent and comparable assessments of various aspects of ankle function, including range of motion, balance, proprioception, strength, and agility.15,41 Proprioceptive testing also provides objective measures for evaluating an athlete’s progress through the rehabilitation process and readiness to return to play. 15
Relationship between mechanical instability caused by an ATFL tear and functional instability from proprioceptive impairment and reduced neuromuscular control further contributing to future instability events.
Treatment
Active Movement Training
Active movement training involves exercises that engage the patient’s muscles to move the ankle joint through its range of motion, helping to improve flexibility, strength, and proprioception.
In patients with chronic ankle instability, active movement training improves stability, balance, proprioception, and self-reported functional outcomes. 2 This approach has been found to be beneficial across different age groups, with improvements observed in joint position sense, static balance, and dynamic balance.
Ankle strengthening exercises performed on unstable supporting surfaces significantly improved proprioceptive sense and dynamic balance ability in adults with functional ankle instability. 29 Nam et al 65 demonstrated that visual feedback balance training combined with ankle joint exercises led to improved balance and reduced ankle instability. While exercises on unstable surfaces appear to challenge the central nervous system’s capacity to process the proprioceptive signals for balance, they may not directly target peripheral ankle proprioception. 44 This suggests that the benefits of unstable surface training may be more related to central nervous system processing adaptations rather than local ankle proprioception improvements.
For stroke patients, proprioceptive training based on an ankle-foot robot, which incorporates active movement, has been shown to improve proprioception and effectively enhance motor function and walking ability. 61 In patients with multiple sclerosis, a combination of passive stretching and active movement training using an ankle rehabilitation robot led to increases in active range of motion, muscle strength, balance, and abmulation. 54
Somatosensory Stimulation
Somatosensory stimulation in the context of ankle stability typically involves exercises aimed at the intrinsic foot muscles with the goal of enhancing balance and postural control. The Short-Foot Exercise, Towel-Curl Exercise, and toe-training programs are examples of such exercises that have shown positive effects on self-reported balance, instability, somatosensory function, and functional aspects in patients with ankle instability.28,40 Vibratory stimulation is another form of somatosensory stimulation that may be helpful for proprioception.11,39,57,89
Force Reproduction Training
Force reproduction training aims to improve an individual’s ability to accurately sense a force and then produce and control a force output. It is thought that in the context of ankle stability, this type of training can help individuals with ankle instability to better control their ankle movements and improve proprioception. 77 Smith et al 77 found that a 6-week protocol of force sense reproduction technique increased inversion and eversion strength in a group of patients with functional ankle instability compared to a control group.
Docherty et al 19 investigated the relationship between contralateral force sense, joint reposition sense, and functional ankle instability in a study involving 60 participants. They found a significant positive correlation between variable error force sense at 10% maximal voluntary isometric contraction and ankle instability, indicating that deficits in low load force sense are present in individuals with ankle instability. 19 Interestingly, although force sense deficits were observed, no significant relationship was found between ankle instability and inversion or eversion joint reposition sense. 19 A related study by Docherty et al 22 found that force sense variable error at both 10% and 30% maximal voluntary isometric contraction was positively correlated with functional ankle instability.
Arnold and Docherty 4 investigated the relationship between low-load force sense (10% of maximal voluntary isometric contraction), strength, injury severity, and the occurrence of functional ankle instability after ankle sprain on the injured and uninjured side. The study found that both injury severity and overestimation of force appear to be contributors to functional ankle instability. The injured ankle overestimates the force generated, which suggests decreased force perception by the injured ankle. Clinically, this may translate to inadequate muscle response to externally applied loads, resulting in decreased joint stability. These results were unilateral and restricted to the injured side, so the authors suggest the damage occurs to the peripheral force sensors rather than at the level of the central nervous system. 4
Duration of Therapy
The effect of therapy intervention duration on proprioceptive gains in ankle instability varies across studies, but generally, measurable gains can be noticed as soon as 4 weeks, and most studies report on programs between 4 and 6 weeks in duration.49,69,88 Longer duration studies tend to show more significant improvements, with nonresponders identified within 6 weeks. 49 Additionally, the type of intervention, not just duration, plays a crucial role in proprioceptive gains.51,73,88
Evidence Gaps and Limitations
Several evidence gaps and limitations remain that limit a comprehensive review of proprioception and the conclusions that may be drawn. First, there is significant variability in the proprioception measurement techniques across studies. This lack of standardization limits direct comparison across studies. Second, there is significant heterogeneity across studies in the study populations (athletic participation, age, sex, etc). Third, most studies are limited by small sample sizes, short follow-up periods, and limited long-term data. Finally, these limitations highlight the need for future research to standardize assessment tools, study protocols, and rehabilitation protocols to better inform clinical practice and enhance the understanding of ankle instability management.
Author’s Preferred Method: Proprioceptive Rehabilitation Protocol
In addition to a standard clinical examination, the author most commonly uses the modified Romberg test as an initial screening exam for proprioception as this can be carefully performed even in the setting of most acute ligamentous injuries including a moderate ankle sprain. This is also helpful in the nonathlete population who may not be athletic enough to perform advanced examination maneuvers. The SEBT can be very useful in the context of chronic injury in athletes, but it requires athleticism so should not be performed in the setting of significant acute injury. Proprioception deficit is often paired with physical therapy and a home rehabilitation program (Table 2 and Appendix) .
Phases of the Proprioception Rehabilitation Protocol.
A proprioceptive rehabilitation protocol can be performed by most patients with or without the supervision of formal physical therapy. This ankle proprioception protocol is designed to guide gradual recovery following an instability episode, postoperative ankle ligament repair or fracture, proprioceptive deficits in older adults, or for athletes and active individuals aiming to improve balance and proprioception. The development of this protocol involved incorporating well-established rehabilitation principles and prior studies on proprioceptive training, sensorimotor retraining, and neuromuscular control. It integrates various methods, such as somatosensory stimulation, progressive balance exercises, resistance training, and sports-specific drills. The protocol progresses from passive exercises focused on swelling and pain management to dynamic, sport-specific movements. It is structured into phases, each lasting 2-3 weeks, with the entire process typically taking 8-12 weeks. However, advancement through the phases is based on functional progress rather than a fixed timeline. Patients should transition to the next phase once they can perform the exercises without pain, compensatory movements, or signs of instability. If a patient does not show noticeable improvement within 4-6 weeks, they should be reassessed by a clinician.
The early phases focus on reintroducing light movement and joint awareness, enhancing proprioceptive feedback through exercises like gentle range of motion, weight shifts, and tactile stimulation. These exercises improve joint stability and encourage the ankle to adapt to varying forces and positions, establishing foundational proprioception while minimizing the risk of reinjury.
As stability improves, controlled strength and sensorimotor coordination are added, with exercises incorporating active movement, agility, and controlled force production using a bathroom scale. Later phases emphasize dynamic stability, functional proprioception, and sport-specific adaptation, challenging the ankle to respond accurately to rapid movements and higher impacts. By combining balance, somatosensory input, and force reproduction, this protocol develops comprehensive proprioceptive awareness and joint control, equipping the ankle to withstand everyday or athletic activities confidently and safely.
If more advanced rehabilitation is of interest, more complex and sport-specific exercises can be introduced. These may include dynamic balance exercises, drop landing exercises, plyometrics, and functional movement patterns relevant to the patient’s activities or sport.33,69 The program should be tailored to the individual’s needs and goals, with regular assessment to guide progression.6,33,46,69
Conclusion
Proprioception plays a crucial role in ankle stability, involving complex interactions between peripheral mechanoreceptors, visual and vestibular inputs, central processing, and neuromuscular control. The ankle joint contains various types of proprioceptors, including muscle spindles, Golgi tendon organs, and cutaneous mechanoreceptors, which provide sensory feedback about joint position and movement. Impairments in proprioception, often resulting from injury or chronic instability, can substantially impact ankle function and increase the risk of recurrent injuries. Assessment of proprioceptive deficits typically involves measures of joint position sense, force sense, and balance control, though the relationship between these measures is not fully understood.
Interventions to improve proprioception and ankle stability should incorporate a progressive approach, beginning with basic exercises and advancing to more complex, functional movements. Active movement training, somatosensory stimulation, and force reproduction exercises have shown promise in enhancing proprioceptive acuity and overall ankle function. However, the optimal duration and specific components of proprioceptive training programs remain subjects of ongoing research. Clinicians should consider individual patient factors, such as age and injury history, when designing rehabilitation protocols. Future research should continue to explore the most effective combinations of interventions and their underlying mechanisms to optimize outcomes for patients with ankle instability.
Supplemental Material
sj-pdf-1-fao-10.1177_24730114251374662 – Supplemental material for Contemporary Review: Proprioception in Ankle Stability
Supplemental material, sj-pdf-1-fao-10.1177_24730114251374662 for Contemporary Review: Proprioception in Ankle Stability by James R. Jastifer in Foot & Ankle Orthopaedics
Footnotes
Appendix: Proprioception Rehabilitation Protocol
Ethical Approval
Ethical approval was not sought for the present study.
Funding
The author received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
