The sensation of passive movement at the metatarso-phalangeal joint of the great toe in man. man

Sensory Factors in the Voluntary Application of Pressure

The experiments described attempt to assess the extent of sensory control of voluntary movements of the forearm and finger when the contractions of the muscles concerned are approximately isometric.

In the first two experiments, records were obtained of the accuracy with which subjects were able to reproduce a particular pressure with the ulnar border of the hand at different pressure values and rates of application. Results show a statistically significant increase in error of reproduction of pressure as the pressure applied decreases and the rate of application is increased.

In the third experiment, using an applied force of 25 gms. weight, a significant difference in accuracy of reproduction of finger pressure between the maximum and a slower rate of application is also shown, but not when the digital nerves are blocked by a local anaesthetic. Furthermore, there is no significant difference in accuracy of reproduction of finger pressure between the anaesthetized and unanaesthetized condition at the fastest rate of application. On the other hand, at the slow rate of application, there is an increasingly significant difference between the anæsthetized and unanaethetized condition as the applied force is reduced below 400 gms. weight, in favour of the control condition.

In the fourth experiment, subjects were trained to apply a force of 25 gms. weight using a small area of skin on the palmar surface of the index finger, then tested for their ability to reproduce the same force before and after changing the size of the area of application. Results show a marked change in applied force corresponding to the change in size of skin area used.

It is concluded that below an applied force of about 400 gms. weight, the maximum accuracy in reproduction of finger pressure is dependent upon cutaneous receptors.

The results of these experiments are discussed in relation to evidence from other experimental, clinical and animal studies and it is suggested that the major function of afferent impulses from a limb in the initiation of voluntary movements is probably facilitatory rather than sensory.

Effect of Mass Loading on the Performance of a Linear Positioning Task

To determine the effect of mass loading on the performance of a skilled perceptual-motor task, measures of performance (in terms of number of correct responses) were obtained for 40 blindfolded undergraduate subjects on a linear positioning task under conditions of 0-gm., 909-gm., 1,818-gm., 2,727-gm., and 3,636-gm. manipulandum loads. With respect to the performance measure, the increasing load conditions produced an inverted U-function, with 1,818 gm. resulting in the best performance and 0 gm. producing the poorest performance. It was concluded that skilled perceptual-motor performance can be improved by optimizing the physical characteristics of the manipulandum. The results were interpreted in terms of the augmentation of both attention and kinesthetic information.

Reliability and validity of using the Lokomat to assess lower limb joint position sense in people with incomplete spinal cord injury

Background

Proprioceptive sense (knowing where the limbs are in space) is critical for motor control during posture and walking, and is often compromised after spinal cord injury (SCI). The purpose of this study was to assess the reliability and validity of using the Lokomat, a robotic exoskeleton used for gait rehabilitation, to quantitatively measure static position sense of the legs in persons with incomplete SCI.

Methods

We used the Lokomat and custom software to assess static position sense in 23 able-bodied (AB) subjects and 23 persons with incomplete SCI (American Spinal Injury Association Impairment Scale level B, C or D). The subject’s leg was placed into a target position (joint angle) at either the hip or knee and asked to memorize that position. The Lokomat then moved the test joint to a “distractor” position. The subject then used a joystick controller to bring the joint back into the memorized target position. The final joint angle was compared to the target angle and the absolute difference was recorded as an error. All movements were passive. Known-groups validity was determined by the ability of the measure to discriminate between able-bodied and SCI subjects. To evaluate test-retest reliability, subjects were tested twice and intra-class correlation coefficients comparing errors from the two sessions were calculated. We also performed a traditional clinical test of proprioception in subjects with SCI and compared these scores to the robotic assessment.

Results

The robot-based assessment test was reliable at the hip and knee in persons with SCI (P ≤ 0.001). Hip and knee angle errors in subjects with SCI were significantly greater (P ≤ 0.001) and more variable (P < 0.0001) than in AB subjects. Error scores were significantly correlated to clinical measure of joint position sense (r ≥ 0.507, P ≤ 0.013).

Conclusions

This study shows that the Lokomat may be used as a reliable and valid clinical measurement tool for assessing joint position sense in persons with incomplete SCI. Quantitative assessments of proprioceptive deficits after neurological injury will help in understanding its role in the recovery of skilled walking and in the development of interventions to aid in the return to safe community ambulation.

Electronic supplementary material

The online version of this article (doi:10.1186/1743-0003-11-167) contains supplementary material, which is available to authorized users.

The representation of egocentric space in the posterior parietal cortex

The posterior parietal cortex (PPC) is the most likely site where egocentric spatial relationships are represented in the brain. PPC cells receive visual, auditory, somaesthetic, and vestibular sensory inputs; oculomotor, head, limb, and body motor signals; and strong motivational projections from the limbic system. Their discharge increases not only when an animal moves towards a sensory target, but also when it directs its attention to it. PPC lesions have the opposite effect: sensory inattention and neglect. The PPC does not seem to contain a "map" of the location of objects in space but a distributed neural network for transforming one set of sensory vectors into other sensory reference frames or into various motor coordinate systems. Which set of transformation rules is used probably depends on attention, which selectively enhances the synapses needed for making a particular sensory comparison or aiming a particular movement.

The proprioceptive senses: their roles in signaling body shape, body position and movement, and muscle force

This is a review of the proprioceptive senses generated as a result of our own actions. They include the senses of position and movement of our limbs and trunk, the sense of effort, the sense of force, and the sense of heaviness. Receptors involved in proprioception are located in skin, muscles, and joints. Information about limb position and movement is not generated by individual receptors, but by populations of afferents. Afferent signals generated during a movement are processed to code for endpoint position of a limb. The afferent input is referred to a central body map to determine the location of the limbs in space. Experimental phantom limbs, produced by blocking peripheral nerves, have shown that motor areas in the brain are able to generate conscious sensations of limb displacement and movement in the absence of any sensory input. In the normal limb tendon organs and possibly also muscle spindles contribute to the senses of force and heaviness. Exercise can disturb proprioception, and this has implications for musculoskeletal injuries. Proprioceptive senses, particularly of limb position and movement, deteriorate with age and are associated with an increased risk of falls in the elderly. The more recent information available on proprioception has given a better understanding of the mechanisms underlying these senses as well as providing new insight into a range of clinical conditions.

Preoperative proprioceptive training in patients with total knee arthroplasty

Proprioceptive deficiencies due to osteoarthritis and arthroplasty have been repeatedly reported. Proprioceptive training, which leads to an economisation of movements and supports energy-saving movement patterns, has become popular in athletes, but not in rehabilitation yet. The aim of this randomised phase IIb study was to evaluate whether preoperative proprioceptive training would influence postoperative balance and function in activities of daily life in patients undergoing total knee arthroplasty. Subjects with severe osteoarthritis of the knee scheduled for TKA were randomised to either a control group (CG) or a training group (TG). All patients were examined 6 weeks before and 6 weeks after TKA, patients of the TG also one day before surgery, i.e. after six weeks of preoperative proprioceptive training, in order to evaluate the influence of training without TKA. Evaluation included balance assessment using the Biodex Stability System, as well as measurements of gait speed and clinical outcome using the WOMAC and Knee Society Score. As opposed to the CG, stance stability improved significantly in the TG (Biodex OSI (p=0.045), APSI (p=0.029)) 6 weeks after TKA. There was a significant improvement in KSS, WOMAC pain and stiffness in both groups after TKA. Preoperative proprioceptive training in patients undergoing TKA resulted in improved standing balance, but no difference in clinical outcome was observed between the two groups.

Does the nervous system depend on kinesthetic information to control natural limb movements?

This target article draws together two groups of experimental studies on the control of human movement through peripheral feedback and centrally generated signals of motor commands. First, during natural movement, feedback from muscle, joint, and cutaneous afferents changes; in human subjects these changes have reflex and kinesthetic consequences. Recent psychophysical and microneurographic evidence suggests that joint and even cutaneous afferents may have a proprioceptive role. Second, the role of centrally generated motor commands in the control of normal movements and movements following acute and chronic deafferentation is reviewed. There is increasing evidence that subjects can perceive their motor commands under various conditions, but that this is inadequate for normal movement; deficits in motor performance arise when the reliance on proprioceptive feedback is abolished either experimentally or because of pathology. During natural movement, the CNS appears to have access to functionally useful input from a range of peripheral receptors as well as from internally generated command signals. The unanswered questions that remain suggest a number of avenues for further research.

Implications of neural networks for how we think about brain function

Engineers use neural networks to control systems too complex for conventional engineering solutions. To examine the behavior of individual hidden units would defeat the purpose of this approach because it would be largely uninterpretable. Yet neurophysiologists spend their careers doing just that! Hidden units contain bits and scraps of signals that yield only arcane hints about network function and no information about how its individual units process signals. Most literature on single-unit recordings attests to this grim fact. On the other hand, knowing a system's function and describing it with elegant mathematics tell one very little about what to expect of interneuronal behavior. Examples of simple networks based on neurophysiology are taken from the oculomotor literature to suggest how single-unit interpretability might decrease with increasing task complexity. It is argued that trying to explain how any real neural network works on a cell-by-cell, reductionist basis is futile and we may have to be content with trying to understand the brain at higher levels of organization.

Electrophysiological analysis of the perception of passive movement

The goal of the present study was to determine the electrophysiological correlate of the threshold of perception of passive motion (TPPM) in a group of healthy individuals. We expect a different pattern of activation over the frontoparietal network produced by the conscious perception of the passive movement. Ten right-handed male volunteers, between 20 and 30 years of age, were submitted to the threshold of perception of passive motion (TPPM) task in a proprioception testing device (PTD). The device was designed to passively move the arm in internal and external rotations about the shoulder joint. Participants were instructed to press a hand-held switch every time movement of the shoulder was detected. Electromyographic (EMG) and electroencephalographic (EEG) activities were acquired during the task. Passive movement of the shoulder joint was followed by a clear and prolonged decrease in the signal magnitude of the electroencephalogram. The electrophysiological correlate of the TPPM was characterized by the establishment of a frontoparietal network, during the processing of somatosensory information.

Proprioceptive signals contribute to the sense of body ownership

The sense of body ownership, knowledge that parts of our body ‘belong’ to us, is presumably developed using sensory information. Cutaneous signals seem ideal for this and can modify the sense of ownership. For example, an illusion of ownership over an artificial rubber hand can be induced by synchronously stroking both the subject’s hidden hand and a visible artificial hand. Like cutaneous signals, proprioceptive signals (e.g. frommuscle receptors) exclusively signal events occurring in the body, but the influence of proprioceptors on the sense of body ownership is not known. We developed a technique to generate an illusion of ownership over an artificial plastic finger, using movement at the proximal interphalangeal joint as the stimulus. We then examined this illusion in 20 subjects when their index finger was intact and when the cutaneous and joint afferents from the finger had been blocked by local anaesthesia of the digital nerves. Subjects still experienced an illusion of ownership, induced by movement, over the plastic finger when the digital nerves were blocked. This shows that local cutaneous signals are not essential for the illusion and that inputs arising proximally, presumably from receptors in muscles which move the finger, can influence the sense of body ownership. Contrary to other studies, we found no evidence that voluntary movements induce stronger illusions of body ownership than those induced by passive movement. It seems that the congruence of sensory stimuli ismore important to establish body ownership than the presence of multiple sensory signals.

Cutaneous afferents provide a neuronal population vector that encodes the orientation of human ankle movements

The aim of this study was to analyse the directional coding of two-dimensional limb movements by cutaneous afferents from skin areas covering a multidirectional joint, the ankle. The activity of 89 cutaneous afferents was recorded in the common peroneal nerve, and the mean discharge frequency of each unit was measured during the outward phase of ramp and hold movements imposed in 16 different directions. Forty-two afferents responded to the movements in the following decreasing order (SA2, n = 24/27; FA2, n = 13/17; FA1, n = 3/24; SA1, n = 2/21). All the units activated responded to a specific range of directions, defining their 'preferred sector', within which their response peaked in a given direction, their 'preferred direction'. Based on the distribution of the preferred directions, two populations of afferents, and hence two skin areas were defined: the anterior and the external lateral parts of the leg. As the directional tuning of each population was cosine shaped, the neuronal population vector model was applied and found to efficiently describe the movement direction encoded by cutaneous afferents, as it has been previously reported for muscle afferents. The responses of cutaneous afferents were then considered with respect to those of the afferents from the underlying muscles, which were previously investigated, and an almost perfect matching of directional sensitivity was observed. It is suggested that the common movement-encoding characteristics exhibited by cutaneous and muscle afferents, as early as the peripheral level, may facilitate the central co-processing of their feedbacks subserving kinaesthesia.

The detection of human finger movement is not facilitated by input from receptors in adjacent digits

These experiments were designed to determine whether cutaneous input from a digit provides a general facilitation of the detection of movements applied to an adjacent digit. The ability to detect passive movements at the proximal interphalangeal joint of the right index finger was measured when cutaneous (and joint) input was removed (using local anaesthesia) from the tip of one or both digits adjacent to the test finger (16 subjects). The same parameter was also measured when input was artificially increased by stimulation of the adjacent digits at three intensities: below, above and at perceptual threshold (PT; 15 subjects). Detection of flexion or extension movements was not altered by anaesthesia of one or both adjacent digits. Since it was possible that too few tonically active afferents in the hand had been blocked to reveal an effect, the median nerve was blocked, with movements applied to the little finger, causing no measurable impairment in acuity (three subjects). Simultaneous electrical stimulation of the tips of the adjacent digits at intensities above PT impaired movement detection, but had no effect when delivered at or below PT. To test whether the effect of detectable electrical stimuli was due to a specific interaction between the artificial input and the input evoked by moving the digit, or due to mental distraction, stimuli were delivered above PT to either the left or right little finger, or the test index finger during movement of the index finger. Electrical stimulation of the index finger significantly reduced detection by approximately 50%, but stimulation of the remote little fingers did not. Electrical stimulation is a non-natural stimulus, so a "natural" stimulus was applied by continuously stroking the tips of the adjacent digits with a brush (10 subjects). The natural stimulus also significantly reduced movement detection by approximately 50%. Together, these findings suggest that tonic inputs from digital nerve afferents adjacent to, or more remote from the passively moved finger do not facilitate movement detection. However, the reduced detection during stimulation of the adjacent digits shows that there is nevertheless some interaction between the various proprioceptive inputs from the digits.

Factors Contributing to Chronic Ankle Instability: Kinesthesia and Joint Position Sense

OBJECTIVE: To present a comprehensive review of the influence of altered kinesthesia and joint position sense on chronic ankle instability and to present a model connecting deficits in ankle position sense with the increased risk of sustaining lateral ankle sprains. DATA SOURCES: I searched MEDLINE for the years 1966-2001 using the key words ankle and kinesthesia or position sense and books on proprioception. DATA SYNTHESIS: Study findings suggest a risk for unprovoked lateral ankle sprains when the lateral border of the foot accidentally catches the ground surface during the late swing phase of normal locomotion. In normal situations, the lateral border of the foot clears the ground by only 5 mm, and a small increase in ankle-position error may substantially increase the risk of a collision. Findings of affected kinesthesia and joint position sense in subjects with chronically unstable ankles dominate over studies showing nonsignificant results, but the answer is far from clear. CONCLUSIONS/RECOMMENDATIONS: Changes in joint position sense and kinesthesia of a magnitude found in subjects with chronically unstable ankles can lead to an increased risk of sustaining lateral ankle sprains. Results from a small number of studies suggest that balance and coordination training can restore the increased uncertainty of joint positioning to normal levels.

Dynamic knee stability: current theory and implications for clinicians and scientists

We will discuss the mechanisms by which dynamic knee stability may be achieved and relate this to issues that interest clinicians and scientists concerned with dynamic knee stability. Emphasis is placed on the neurophysiologic evidence and theory related to neuromuscular control. Specific topics discussed include the ensemble firing of peripheral mechanoreceptors, the potential for muscle stiffness modulation via force and length feedback, postural control synergies, motor programs, and the neural control of gait. Factors related to answering the difficult question of whether or not knee ligament injuries can be prevented during athletic activities are discussed. Prevention programs that train athletes to perform their sport skills in a safe fashion are put forth as the most promising prospect for injury prevention. Methods of assessing neuromuscular function are reviewed critically and the need for future research in this area is emphasized. We conclude with a brief review of the literature regarding neuromuscular training programs.

Joint position sense in total knee arthroplasty

Seventeen postoperative total knee arthroplasty (TKA) patients were evaluated using two tests of knee joint position sense. Young controls and age-matched controls underwent identical tests. The TKA patients also underwent gait analysis, including foot switch stride analysis, and clinical evaluation using a standard scoring system. Results showed statistically significant decreases in joint position sense from young controls to old controls, and further significant decreases with joint disease; however, no further worsening was noted as a result of TKA. The abnormal gait parameters seen in TKA patients correlated as well with position sense as with clinical score. Strongest correlations were seen when a combined clinical and proprioceptive score was compared with gait parameters. In spite of alleviation of pain and correction of deformity, normal gait and function are not typically achieved after total knee replacement. Irreversible loss of joint proprioceptive function due to the disease process may be a major factor in the discrepancy between clinical and functional outcomes of total joint arthroplasty. Furthermore, loss of proprioception and the resulting abnormal gait patterns may place increased stress on components and contribute to loosening. In addition, an association between degenerative joint disease and decline in proprioception is suggested.

Normal shoulder proprioception and the effect of lidocaine injection

The purpose of this study was to investigate the effect of age, dominance, joint position, and lidocaine injection on proprioception of the normal shoulder. Position sense and the detection of passive shoulder motion were investigated in 40 young (20 to 30 years) and old (50 to 70 years) subjects. An additional 20 young subjects were tested before and after a glenohumeral (n = 10) or a subacromial (n = 10) lidocaine injection was performed. A significant decline occurred in proprioception between the young and old age groups. No difference was observed between dominant and nondominant sides. Position sense was consistently less accurate in the maximum range of motion tested when compared with the lesser ranges tested for flexion and abduction. No differences were identified in the ability to detect motion in flexion, abduction, and external rotation in the younger group, whereas in the older group a difference was observed in flexion. No learning effect was detected for any test trial. No significant changes occurred in proprioceptive ability after either glenohumeral or subacromial lidocaine injection was performed.

Movement detection at the human big toe

1. To be detected, movements of the interphalangeal joint of the big toe must be greater than at other joints. This poor acuity may arise because the anatomy of the foot and ankle results in poor coupling between the toe and the muscles that operate it. To vary this coupling, the effect of ankle position on proprioceptive acuity at the toe was measured. 2. We measured proprioceptive acuity at the toe with the ankle in different positions and found that ankle plantarflexion did improve acuity. This implies that, with the ankle at mid-range or dorsiflexed, toe movement is inadequately transferred to muscle fascicles. 3. To determine actual changes in fascicle length of the toe extensor, movements of extensor hallucis longus near the toe and at the muscle-tendon junction were measured during surgical exposure in one subject. Ankle position greatly affected movement transfer from toe to muscle-tendon junction: no tendon movement was transferred with the ankle dorsiflexed, but all movement was transferred with the ankle plantarflexed. 4. When the relationship between joint rotation and muscle fascicle length measured in vivo was used to express the smallest detectable movements of the toe as proportional changes in muscle fascicle length, these detectable changes were similar to those at all other limb joints. This suggests that change in muscle fascicle length is of major interest to the nervous system.

Factors associated with ankle injuries. Preventive measures

A sense of foot position in humans is precise when barefoot, but is distorted by athletic footwear, which accounts for the high frequency of ankle sprains in shod athletes. It is unclear whether taping and rigid and semi-rigid devices protect against ankle sprains, as all of the studies suggesting this are flawed by inadequate controls. If these devices do protect the ankle, it is not through added support but rather through a partial correction of the deceased foot position awareness caused by footwear. Since taping and rigid and semi-rigid devices interfere with normal movement, there is concern that these might actually increase the frequency of injury at the ankle and/or at different locations. In this respect, taping is less of a concern because it interferes least with normal movement. The best solution for reducing ankle sprains in shod athletes is the use of more advanced footwear to retain maximal tactile sensitivity, thereby maintaining an awareness of foot position comparable to that of the barefoot state or perhaps even improving on it.

The sensory innervation of the shoulder joint of the mouse

The ultrastructure and location of sensory nerve endings in the shoulder-joint capsule, its tendinous reinforcements and in the periarticular connective and muscle tissue have been studied by means of light and electron microscopy in adult female white NMRI-F2 laboratory mice, aged 2.5-13 months. Most of the sensory nerve endings were detected in the fibrous layer of the joint capsule or in the inserting tendons. The identified lamellated corpuscles of the Pacini type are small and sometimes associated with Golgi tendon-organs. Large Vater-Pacini corpuscles were not detected. Ruffini corpuscles are found in small numbers only in the moderately dense connective tissue of the joint capsule. Golgi tendon organs were found mainly at the muscle-tendon junction of the muscles surrounding the joint. Muscle spindles have been identified mainly in periarticular muscles close to the muscle-tendon junctions. The number and distribution of the different types of mechanoreceptors investigated in the present study suggest that periarticular corpuscular sensory nerve endings play an important role in shoulder-joint control and mobility. The occurrence of small uniformly shaped lamellated corpuscles of the Pacini type in qualitatively different areas of surrounding tissue implies that they are susceptible to different kinds of mechanical stimuli.

Ankle taping improves proprioception before and after exercise in young men

Ankle sprains are common sports injuries. Inadequate foot position awareness is thought to be the fundamental cause of these injuries. Ankle taping may decrease risk of injury through improving foot position awareness. The benefit of taping is thought to decrease with duration of exercise because of poor tape adherence to human skin. This study was a randomized, crossover, controlled comparison experiment that tested the hypothesis that ankle taping improves foot position awareness before and after exercise. A sample of 24 healthy young blindfolded volunteers, wearing their own athletic shoes, indicated perceived slope direction and estimated slope amplitude when bearing full body weight and standing on a series of blocks. The top slope of the blocks varied between 0 degree and 25 degrees, in 2.5 degrees increments, to orient the plantar surface with respect to the leg toward pronation, supination, plantarflexion, and dorsiflexion, relative to its position on a flat surface. Foot position awareness, which was considered the reciprocal of surface slope estimate error, varied with testing condition, particularly when surface slope was greater than 10 degrees, presumably the most important range considering ankle injuries. In this higher range absolute position error was 4.23 degrees taped, and 5.53 degrees untaped (P < 0.001). Following exercise, in the higher range absolute position error was 2.5% worse when taped and 35.5% worse when untaped (P < 0.001). These data support the hypothesis that ankle taping improves proprioception before and after exercise. They also indicate that foot position awareness declines with exercise. Compared to barefoot data (position error 1.97 degrees), foot position error was 107.5% poorer with athletic footwear when untaped (absolute position error 4.11 degrees), and 58.1% worse when taped (position error 3.13 degrees). This suggests that ankle taping partly corrects impaired proprioception caused by modern athletic footwear and exercise. Footwear could be optimized to reduce the incidence of these injuries.

Detection of movements imposed on human hip, knee, ankle and toe joints

1. The angular displacements necessary for 70% correct detection were determined in normal subjects at the hip, knee and ankle joints, and the interphalangeal joint of the big toe. Angular velocities between 0.1 and 50 deg s-1 were tested. The hip and knee joints were tested in slight flexion and the ankle and toe joints were tested in the mid-range of the normal excursion. The joints were carefully supported for testing and the muscles acting at the joints were relaxed. 2. When detection thresholds and velocities were assessed in terms of angular displacements and angular velocities, proprioceptive performances at the hip, knee and ankle joints were superior to that at the toe joint. 3. When detection levels and displacement velocities were expressed in terms of linear displacements and velocities at the tip of the extended toe for all four joints, instead of in angular terms, the ankle gave the best performance and the hip and knee the worst. 4. The detection level and velocity data were expressed also in terms of proportional changes in the fascicle lengths of muscles operating these joints. Analysis in these terms showed that performance was similar at the hip, knee and ankle joints, but that performance for the toe was much poorer than for the other joints. 5. These results for the hip, knee and ankle are similar to those previously measured for the elbow and distal interphlangeal joint of the finger, and are consistent with the theory that muscle fascicle length is the variable of significance to the central nervous system. However, the proprioceptive performance at the big toe is notably poorer than all other joints studied and analysed in terms of this variable.

Comparison of Open versus Closed Kinetic Chain Test Positions for Measuring Joint Position Sense

The purpose of this study was to determine if a difference exists in the reproducibility of knee joint flexion angles in an open versus a closed kinetic chain. Thirty generally healthy subjects (12 males, 18 females; mean age 23.8 years) participated. Subjects actively reproduced small, medium, and large knee flexion angles (with target angles of 15°, 45°, and 75°, respectively) in an open and a closed kinetic chain while being videotaped. Goniometric measurements were taken from the videotape of initial and reproduced joint angles. Data were analyzed using ANOVA with repeated measures on kinetic chain test position and joint angle. Subjects more accurately reproduced knee flexion angles in a closed kinetic chain position. The main effect for angle and the interaction of angle and test position were nonsignificant. The results indicate that knee joint position is more accurately reproduced in closed kinetic chain. Closed kinetic chain testing is also a more functional assessment of joint position sense, and thus closed kinetic chain assessment of lower extremity joint position sense is recommended.

Effect of fatiguing maximal isokinetic quadriceps contractions on ability to estimate knee-position

This randomized controlled study compared the accuracy of knee positioning by 8 women after fatiguing maximal isokinetic contractions of the quadriceps with those of 8 controls who performed no exercise. The mean algebraic error (AE) and variable error (VE) showed a significant posttest improvement for the control group after a 5-min, intertrial period. There was no change in accuracy of knee positioning postexercise, however, for the experimental group. These findings suggest that, while a single bout of fatiguing knee exercises may not alter absolute accuracy of knee positioning, the movements may undermine the relative proficiency attainable by learning. They suggest a role for central as well as peripheral mechanisms in mediating this sensory modality.

Tactile discrimination of thickness

The ability of human subjects to discriminate plane metal plates of different thickness was measured using of forced-choice paradigm. The plates, made by electroplating a thin layer of copper onto flat brass shims, were gripped between the thumb and the index finger. Subjects were presented with either 2 standard plates (0.2 mm thick), or a standard plate and a test plate that was slightly thicker, and were required in state which alternative had occurred. When the edges of the plates could not be touched, a difference in thickness of about 0.075 mm could be discriminated. Surprisingly, when the edges were included in the grip, performance did not improve. All hypotheses of strategies used by the subjects required them to sense the angles of the finger joints with a precision of about 0.1 degrees.

Postural stability after total hip replacement

Changes in postural stability were recorded before and after total hip replacement using a specially designed computer-assisted forceplate system. Twenty-one patients with unilateral osteoarthritis of the hip were randomised into two groups after operation with either a cemented Charnley or a non-cemented HP-Garches prosthesis. Postural stability was improved in both groups one year after operation and the sway pattern became normal.

Position sense at the proximal interphalangeal joint of the human index finger

1. The ability of eleven normal subjects to match the position of the proximal interphalangeal joints was tested. The right index finger (target finger) was moved to a given position and the subject was required to match this with the left index finger (matching finger). 2. Digital nerve block of the matching finger resulted in substantial impairment in matching performance in seven out of eight subjects. 3. Anaesthesia of the target finger in two subjects also produced obvious position matching deficit, in a pattern consistent with subjective sensation of target finger position. 4. The effects of digital nerve block were specific, as neither injection of saline into the matching finger, nor anaesthesia of adjacent fingers, impaired performance. 5. In one subject, injection of local anaesthetic into the synovial cavity of the matching finger also resulted in impairment of matching performance, indicating that articular receptors contribute to position sense at this joint. 6. Passive displacement of the matching finger did not produce significantly greater errors than those occurring with active finger positioning either under control conditions or during digital nerve block of the matching finger. 7. Although digital nerve block produced substantial impairment of matching performance, there was not complete loss of proprioceptive sensation, suggesting that muscle receptors also contribute. This was confirmed in experiments where isotonic loading of the matching finger while it was anaesthetized resulted in significant alteration in matching performance compared to anaesthesia alone. 8. It is concluded that no one source of afferent input can be excluded from contributing to proprioception at the index finger. It is likely that under different operating conditions several afferent sources are required to provide optimal proprioceptive resolution.

The effect of digital nerve block on position sense at the proximal interphalangeal joint of the human index finger

Position matching at the proximal interphalangeal joint of the index finger in human subjects was tested by passive displacement of the right (target) finger and active matching of the left index finger. In 5 subjects it was found that position matching was grossly impaired after digital nerve block of the matching finger. Typically, subjects hyperextended the matching finger when the target finger was held in extension and hyperflexed the matching finger when the target finger was held in flexion. These results suggest that even with active positioning, joint and cutaneous receptors importantly contribute to the awareness of position at this joint.

The role of joint receptors in human kinaesthesia when intramuscular receptors cannot contribute

1. Kinaesthetic acuity was tested at the distal interphalangeal joint of the middle finger when the hand was postured so that the joint was effectively disengaged from its muscular attachments. Subjects were required to detect the direction of 5 deg movements applied at different angular velocities from a mid-position under control conditions, after intra-articular injection of a plasma expander and after intra-articular injection of a local anaesthetic. 2. Kinaesthetic performance was enhanced after the injection of a plasma expander and deteriorated after injection of local anaesthetic. This deterioration could not be explained by spread of the local anaesthesic from the injection site on the dorsum of the joint. 3. The results suggest that the discharge of joint receptors can produce perceived signals of joint movement. Under normal conditions these receptors may duplicate the kinaesthetic input from muscle spindle endings.

Evaluation of ankle joint proprioception following injection of the anterior talofibular ligament*

The purpose of this investigation was to measure ankle joint proprioception preceding and following injection of Xylocaine into the anterior talofibular ligament (ATFL). Previous investigators have indicated that the typical inversion ankle sprain causes decreased afferent input from the joint which results in a proprioceptive deficit at the ankle. It was hypothesized that anesthesia of the ATFL would simulate this proprioceptive deficit. Fourteen individuals were blindfolded and subjected to pre-test proprioceptive measurements on a multiaxial balance evaluator. Xylocaine was introduced into the ATFL and post-test measurements were taken. A significant increase in average time in balance was found following anesthesia of the ATFL. The unexpected results may indicate that multiple trials caused a learning effect. This supports the contention of other investigators that proprioceptive deficits can be improved with training. It is concluded that proprioceptive training should be included in the overall rehabilitation program following ankle sprains. J Orthop Sports Phys Ther 1986;8(2):70-76.

Effect of fatigue on joint position sense of the knee

This study was designed to test position sense of the knee joint before and after fatigue in order to determine whether muscle or capsular receptors are the primary sensors for joint position sense. Reproduction of passive positioning and detection of the onset of motion (kinesthesia) were employed to measure joint position sense. Eleven subjects underwent joint position sense measurement before and after a fatigue protocol. A significant worsening of reproduction of knee joint angle after fatigue was noted (p less than 0.05). Threshold (kinesthesia) showed no statistically significant change after fatigue. A significant correlation of reproduction measurements and threshold measurements prior to fatigue (p less than 0.01) demonstrated that the same neural mechanism is applicable in the rested state, but these variables did not correlate significantly after fatigue. There was a significant correlation between reproduction measurements before and after fatigue (p = 0.018), while no correlation was seen for the pre- and postfatigue threshold measurements, suggesting a change in the neural path after fatigue. Since both tests of joint position sense are affected by fatigue, we conclude that muscle receptors are a prominent, if not primary, determinant of joint position sense, and capsular receptors may have a secondary role. Reproduction ability is decreased, presumably through the loss of efficiency of muscle receptors. The threshold data suggest a change in the mechanism of appreciation after fatigue, possibly due to increased sensitivity of capsular receptors from muscle-fatigue-induced laxity.

Posterior column dysfunction in cervical spondylotic myelopathy

Five patients had cervical spondylotic myelopathy (CSM) with severe prorioceptive sensory loss in the upper and lower limbs. Despite an advanced age, each recovered considerable function following cervical laminectomy, in follow-up periods of 10 to 40 months. The role of newer methods of investigation including CT scanning, somatosensory evoked responses and nuclear magnetic resonance is discussed. The cause of the proprioceptive sensory loss in these patients cannot be definitively determined, but various ischemic and compressive lesions are discussed as possible pathogenetic mechanisms.

Response of slowly adapting articular mechanoreceptors in the cat knee joint to alterations in intra-articular volume

Recordings were obtained from slowly adapting mechanoreceptors innervating the posterior aspect of the cat knee joint capsule. It was observed that, with rising intra-articular volume, initially both intra-articular pressure and the neural discharge increased. This increase was dependent on the rate of fluid accumulation within the joint. However, the joint nerve discharge invariably levelled out despite increasing intra-articular volume and pressure. This suggests that there exists some limit to capsular distension in the posterior joint region beyond which fluid is diverted to other areas of the knee joint.

Functional performance of the knee after intraarticular anesthesia

Ten healthy young volunteers underwent gait analysis and tests of knee joint position sense. Gait analysis included determination of stride characteristics (velocity, cadence, gait cycle, stride length, and single limb support time), force plate analysis, and motion analysis of the knee. The tests of joint position sense examined the ability of the subject to reproduce passive positioning of the knee and the ability to detect change in angle at the knee joint. In a double-blind manner, 10 cc of sterile fluid were injected into the left knee of each volunteer. Five received 2% lidocaine, the other five received sterile saline. All tests were then repeated. No statistically significant difference was observed in any measurement before and after injection in either test group. It is concluded that intraarticular anesthesia has no effect on gait pattern or joint proprioception as measured. Intraarticular local anesthesia is used in sports medicine to alleviate pain during arthroscopy of the knee under local anesthetic. The possibility of permitting damage in the early postoperative period due to loss of joint position sense is addressed in this paper. The results of this study suggest that injection of local anesthetic into a joint with an intact joint capsule does not compromise joint position sense as measured in this study. Furthermore, no change in gait parameters was observed in the functional task of ambulation. It must be noted that no conclusions regarding the loss of pain sensation can be made from the results of this study. Also, no conclusions regarding competitive activity can be drawn from this study.

Passive joint position sense after total hip replacement surgery

Passive joint position sense was tested in 10 subjects after unilateral total hip replacement surgery (which included capsulectomy). Varied initial limb position, amplitude, and velocity of movement were used. The unoperated side was used as a control. Statistically barely significant errors (p less than 0.025) on the operated side were detected at 0.6 degrees per second but not at 2 degrees per second. No significant differences were noted among the different hip positions. The results indicate that the ability to detect passive hip joint position sense remains largely, but not completely, intact after hip joint replacement. The joint capsule, ligaments, and joint surfaces, although not essential for kinesthesia, may provide some limb movement and position information, the absence of which is not now clinically apparent.

Kinaesthetic role of muscle afferents in man, studied by tendon vibration and microneurography

The characteristics of vibration-induced illusory joint movements were studied in healthy human subjects. Unseen by the subject, constant frequency vibration trains applied to the distal tendon of the Triceps or Biceps induced an almost constant velocity illusory movement of the elbow whose direction corresponded to that of a joint rotation stretching the vibrated muscle. Vibration trains of the same duration and frequency applied alternatively to the Biceps and Triceps evoked alternating flexion-extension illusory movements. During successive application of vibration trains at frequencies from 10 to 120 Hz, the perceived velocity of the illustory movements increased progressively from 10 to 70-80 Hz, then decreased from 80 to 120 Hz. The maximal perceived velocity was three times higher during alternating vibration of the Biceps and Triceps than during single muscle stimulation. Unit activity from 15 muscle spindle primary endings and five secondary endings located in Tibialis anterior and Extensor digitorum longus muscles were recorded using microneurography in order to study their responses to tendon vibration and passive and active movements of the ankle. Primary endings were all activated by low amplitude tendon vibration (0.2-0.5 mm) previously used to induce illusory movements of the elbow. The discharge of some was phase-locked with the vibration cycle up to 120 Hz, while others responded one-to-one to the vibration cycle up to 30-50 Hz, then fired in a sub-harmonic manner at higher frequencies. Secondary endings were much less sensitive to low amplitude tendon vibration. Primary and secondary ending responses to ramp and sinusoidal movements of the ankle joint were compared. During the movement, the primary ending discharge frequency was almost constant, while the secondary ending activity progressively increased. During ankle movements the primary ending discharge appeared mainly related to velocity, while some secondary activities seemed related to both movement velocity and joint angle position. Muscle spindle sensory ending responses to active and passive ankle movements stretching the receptor-bearing muscle (plantar flexion) were qualitatively and quantitatively similar. During passive reverse movements (dorsiflexion) most of the sensory endings stopped firing when their muscle shortened. Active muscle shortening (isotonic contraction) modulated differently the muscle spindle sensory ending discharge, which could stop completely, decrease or some times increase during active ankle dorsiflexion. During isometric contraction most of the muscle spindle sensory endings were activated. The characteristics of the vibration-induced illusory movements and the muscle spindle responses to tendon vibration and to active and passive joint movements strengthened the possibility of the contribution of primary endings to kinesthesia, as suggested by several previous works...

The primary articular nerves to the dog knee

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