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Journal of Back and Musculoskeletal Rehabilitation 28 (2015) 689–697 DOI 10.3233/BMR-140570 IOS Press

Additional sensory input improves the strategy of stepping over obstacle in individuals with knee osteoarthritis Kátia S. Pegorettia , Renato Moraesb , Cátia L. Masulloa , Francisco A. Chagas-Netoc, Aline Mirandac , Maurício Kfuri, Jr.c and Débora Bevilaqua-Grossia,∗ a

Postgraduate Program in Rehabilitation and Functional Performance, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil b School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil c Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil

Abstract. BACKGROUND: The use of bandages improves quasi-static posture control in individuals with knee osteoarthritis, but it is unknown whether this increased sensory input influences postural control in dynamic tasks. OBJECTIVE: Assess the effect of bandage use on motor performance and reported pain in individuals with knee osteoarthritis during obstacle crossing. METHODS: Twenty-four individuals with knee osteoarthritis were enrolled. A force plate was used to measure the vertical and anterior-posterior components of the ground reaction force during obstacle crossing, for the trailing and leading legs, under conditions with and without the use of a bandage. Pain was assessed using the visual analogue scale. RESULTS: With use of a bandage, the propulsive time, time to active peak, propulsive peak, passive peak, and active impulse were significantly reduced in the trailing leg, and the braking peak was significantly increased in the leading leg. The pain parameters did not exhibit any variation. CONCLUSIONS: These results suggest that the use of a bandage allowed for a more rapid movement, better estimates of the force applied against the ground in the propulsive stage, and a reduction in the overload on the locomotor system in the loading response stage. Keywords: Knee osteoarthritis, obstacle crossing, ground reaction force, tactile sensory information, bandage

1. Introduction Osteoarthritis (OA) causes significant loss of knee joint proprioception [1], mechanical misalignment, and pain, together accounting for the major functional limitations associated with this disease [2]. Mobility tasks that require weight bearing on the affected limb, ∗ Corresponding author: Débora Bevilaqua-Grossi, Bandeirantes Avenue 3900, Monte Alegre, Ribeirão Preto, SP 14049-900, Brazil. Tel.: +55 16 36024413; Fax: +55 16 36024413; E-mail: [email protected].

such as obstacle crossing, are the most limiting tasks and are associated with the frequent occurrence of falls in the affected population [3,4]. Auxiliary devices, such as bandages, tape, and braces are commonly indicated for patients with knee OA to improve the mechanical alignment of the patellofemoral joint or the tibiofemoral joint [5,6]. Moreover, such devices also provide a sensory component given that they adhere to the skin and stimulate its local mechanoreceptors [7]. Whereas mechanical realignment generally results in reduction in pain [8], the effect of sensory stimulation on the improvement of knee

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690 K.S. Pegoretti et al. / Additional sensory input improves the strategy of stepping over obstacle in individuals with knee osteoarthritis

joint proprioception has not been established [9–12]. Different authors demonstrated that skin stretch in the proximities of the fingers, elbows and knee joints is sufficient to generate an illusion of movement in these articulations [13,14]. It has also been demonstrated that it is possible to reproduce in the contralateral limb the illusory movement due to the stretch of the ipsilateral limb [13–15]. For the knee, a simple manual stretch of the skin in the anterior region of the thigh was enough to generate an illusory perception of knee flexion in that limb and participants actively reproduce it on the contralateral knee [14]. Such results suggest that the sensorial input of cutaneous receptors contributes for the sense of articular position and that the central nervous system can use the tactile information of skin stretch to elaborate descending motor strategies [14,15]. Similarly, it is assumed that the tactile stimuli provided by the auxiliary devices can improve the knee joint position perception in patients with knee osteoarthritis. Such additional information would enhance the cortical representation of the position of lower limb in space, which, once integrated to the rest of the information from the visual, vestibular and somatosensory systems, would make possible the organization of more precise motor strategies [7,14,16,17]. In this regard, auxiliary devices were demonstrated to improve posture control during the performance of standing tasks, namely unipodal and bipodal stances, with or without visual information [7,11] as well as when the support surface is altered [18]. To the best of our knowledge, few studies have investigated the influence of providing additional tactile information on the performance of dynamic tasks in patients with knee OA. Collins et al. [19] reported that the use of a bandage may improve motor performance during unobstructed gait in individuals with knee OA. Nevertheless, it has not been established whether the use of tactile auxiliary devices may also apply in more challenging conditions, such as obstacle crossing, which is a particularly difficult task and is associated with the occurrence of falls in individuals with knee OA. The hypothesis underlying the present study was that the addition of sensory information alters the force, time, and impulse parameters of the vertical and anteriorposterior components of the ground reaction force (GRF). The improvement in obstacle avoidance control due to additional tactile stimulus provided by the bandage may have important implications for therapeutic interventions and rehabilitation. In patients with knee OA,

such additional sensory information may represent a means by which to improve the relationship between the sensory information and the motor activity that is required for the performance of any functional task. Therefore, the aim of the present study was to establish the effect of the use of bandage on the motor performance and report pain of individuals with knee OA during an obstacle crossing task.

2. Methods 2.1. Sample This is a non controlled experimental study. Twentyfour volunteers with knee OA (8 males and 16 females) aged between 50 to 74 years and able to cross a 15cm high obstacle participated in this study. The volunteers were recruited at the orthopedic outpatient clinic of a university hospital, where they were diagnosed following the clinical classification criteria of the American College of Rheumatology [20] and then graded according to Kellgren and Lawrence’s (K&L) radiological criteria [21] based on antero-posterior and lateral views of the affected knee using digitized film. The radiographs were taken within a maximum of six months (average interval of 3.5 months) after data collection to acquire information regarding the grade of OA. Unilateral and bilateral cases of knee OA were included. The Western Ontario McMaster Universities (WOMAC) questionnaire [22,23] was applied to assess the clinical characteristics of OA corresponding to pain, stiffness, and function. Additionally, data were collected on the patient’s history of pain, time since the onset, average pain over the past month, medications being used, treatments, and other health-related conditions. The descriptive data of the sample are given in Table 1. The volunteers were excluded if they had performed physical therapy for the affected knee in the previous six months or if they had a history of lower limb arthroplasty; knee surgery in the previous three months; intra-articular injection of corticosteroids in the previous six months; previous use of external sensory devices, such as tape and/or a brace; or any other clinical condition which might affect gait or cognitive function, as in other associated musculoskeletal conditions, neurological diseases and fracture. Also, eventual concomitant metabolic diseases must be controlled for the participant to take part in the study. All the volunteers had normal vision or vision corrected to normal. They

K.S. Pegoretti et al. / Additional sensory input improves the strategy of stepping over obstacle in individuals with knee osteoarthritis 691 Table 1 Descriptive data of the sample: mean (standard deviation) Unilateral Bilateral knee OA knee OA n = 17 n=7 Age (years) 60.7 (6.5) Body Weight (kg) 75.1 (14.4) Height (m) 1.6 (0.07) 28.6 (5.1) BMI (kg/m2 ) Time of Knee Pain (years) 6.4 (5.3) Pain in the previous month (0–10) 5.6 (2.1) WOMAC – subescale of pain (0–100)* 49.3 (24.6) WOMAC – subescale of stiffness (0–100)* 40.6 (31.9) WOMAC – subescale of function (0–100)* 47.0 (27.0) WOMAC – total score (0–100)* 47.0 (25.7) OA degrees – K&L criteria Degree 1 n=5 Degree 2 n=6 Degree 3 n=9 Degree 4 n=4 ∗ Values

A

close to 100 indicate increased impairment.

were informed regarding the procedures that were included in the study and signed a voluntary informed consent form that was approved by the human research ethics committee of the institution.

2.2. Instrumentation A walkway representing the path to be walked by the volunteers was built for the obstacle-crossing protocol. The walkway consisted of a steel support (60.5 × 45.5 cm) in which a force plate (OR6-7-1000, AMTI, Watertown, USA) was placed. A wooden box was placed before (50 × 54.5 cm) and after (100 × 54.5 cm) the steel support to achieve a straight and even surface. This box prevented any motion of the plate during patient locomotion. A cylindrical obstacle with a 15-cm diameter (obstacle height) was affixed to the force plate (Fig. 1). The height of the obstacle was determined based on the Brazilian norms of urban accessibility [24], which considers curb heights varying between 15 and 20 cm. These heights correspond to 18.75% and 25%, respectively, of the length of volunteers’ legs, (on average, 80 cm). Biomechanical studies of obstacle crossing consider heights between 10% and 30% of the volunteers’ legs [25,26], with an average quite close to that found in the present study . In addition, the force plate was zeroed after placing the obstacle and before each trial. Thus, the constant load of the obstacle over the force plate was not considered while the volunteer performed the crossing.

B

Fig. 1. Photographs illustrating the experimental conditions to which the trailing and leading legs were subjected. It should be noted that the individual depicted in the photograph was not a study participant. Instrumentation: the steel support that contained the force plate is represented in white, together with a cylindrical obstacle (15-cm R diameter) affixed with Velcro tape to the top of the plate. (A) Obstacle crossing: the right leg (R) represents the trailing leg with knee OA. (B) Obstacle crossing: the right leg (R) represents the leading leg with knee OA. The “b” indicates the volunteer’s position before the beginning of the obstacle crossing.

2.3. Protocol The obstacle-crossing task included two variations, which were designated “trailing leg” and “leading leg”. The first task began with the volunteers in a standing position facing the force plate and with the limb with knee OA being moved forward. This limb was designated as the “trailing leg” because it contacted the plate before reaching the obstacle and thus provided sup-

692 K.S. Pegoretti et al. / Additional sensory input improves the strategy of stepping over obstacle in individuals with knee osteoarthritis

Fig. 2. A photograph illustrating the placement of adhesive plaster tape in an individual who did not participate in the study (corresponding to the condition with bandaging).

port to the crossing motion of the contralateral leg, as shown in Fig. 1A. The second task began from a standing position in front of the obstacle, and the limb affected by knee OA being moved forward. For this task, however, the limb designated as the “leading limb” was the first to contact the plate after crossing the obstacle, as shown in Fig. 1B. In cases with bilateral OA, the most affected leg (as reported by the volunteers) was selected to initiate the task. The volunteers performed the obstacle-crossing task either with or without a bandage. The bandage was made of 2.5-cm wide adhesive plaster tape and was sufficiently long to mediolaterally cover the infrapatellar area of the affected knee (Fig. 2). To ensure the best fit to the infrapatellar area, the bandage was placed while the volunteers were in a sitting position with the knee in 90◦ flexion. The fixation of the bandage did not to exert any pressure or patellar realignment force and it was used with the objective of providing only the tactile stimulus of its adherence to the skin. Bandage fixation was performed in the same standardized manner for all the volunteers. Two conditions were then established: either with or without bandaging of the knee affected by OA or, in the bilateral cases, of the most affected knee.

The volunteers were instructed to perform the task safely and at a self-selected (comfortable) speed. Thus, to adapt to the task, the participants repeated each variation on average of three times, during which they were instructed as to its correct performance, more particularly in regard to the proper placement of the foot fully on the plate. The instructions and the verbal commands to perform the obstacle crossing task were standardized and made in the same manner to all the volunteers in all of the experimental conditions. Next, three trials of both variations (i.e., the trailing and leading leg) under both of the conditions (i.e., with and without the bandage) were performed randomly, for a total of 12 trials. A five-minute rest period between the trials with or without the bandage was permitted to allow for the tactile stimulating effect of the bandage to end, particularly when the trials with the bandage were performed first. The volunteers were also allowed to rest during the protocol whenever they felt pain or fatigue. In addition, the assessment of knee pain was performed at three moments: prior to the beginning of the protocol, immediately following the sixth attempt (before the rest period), and at the end of the protocol. Pain was assessed using a visual analogue scale, where zero represented absence of knee pain and ten represented the maximum possible pain [27]. This assessment sought to establish whether the use of bandage is associated with a reduction in pain and, if so, whether such reduction has any influence on the GRF-related variables. In order to avoid influence the data on pain, the use of analgesic drug was not allowed on the day of data collection and the non-steroid anti-inflammatory drugs had to be stable in the fortnight previous to the evaluation. 2.4. Data analysis The force plate signal was sampled at 100 Hz. The GRF data from all three directions (anterior-posterior, medial-lateral, and vertical) were collected, as well as the moments of force around those axes. Due to the nature of the task, only the GRF components of the vertical and anterior-posterior axes were analyzed. The GRF values were normalized to body weight. The following variables were extracted from the GRF vertical component for both the trailing and leading legs: maximum force during weight acceptance (Passive Peak), minimum force at mid-stance (Minimum between Peaks), and maximum force during propulsion (Active Peak). The following corresponding times

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A

B

Fig. 3. Vertical and anterior-posterior force-time curves normalized to body weight, as well as their corresponding variables: (A) passive peak and time to passive peak during weight acceptance; minimum between peaks and time to minimum between peaks at mid-stance; and active peak and time to active peak during the vertical propulsive phase; (B) braking peak and time to braking peak during the breaking phase and propulsive peak and time to propulsive peak during the anterior-posterior propulsive phase.

of occurrence were also measured: time to passive peak, time to minimum between peaks, and time to active peak (Fig. 3A). In addition, the following impulses were represented by the calculated area under the curve: passive impulse and active impulse. The transition between passive and active impulses was defined as the zero-crossing of the force-time curve in the anterior-posterior direction, which represents the instant at which the force crosses the abscissa axis, thus defining the instant when the passive impulse ends and the active impulse begins. The following variables were extracted from the GRF anterior-posterior component for both the trail-

ing and leading legs: maximum braking force (Braking Peak); maximum propulsive force (Propulsive Peak); time to braking peak; time to propulsive peak; and braking and propulsive impulses, using zero-crossing as a reference (Fig. 3B). In regard to the complete task for both the trailing and leading legs, the total stance time was considered, as was the duration of the braking and propulsive periods, using zero-crossing as reference. Moreover, normalization to the stance time was performed to allow for comparisons between the participants under the various conditions and attempts. For this purpose, the beginning of the stance phase (0%) was defined as the contact of the heel (Vertical force > 5 N) with the plate and the end of the stance phase (100%) was defined as the toe-off (Vertical force < 5 N). The force-time curve variables and the pain data were used in the comparison between the conditions with and without bandages. Separate statistical analyses were performed for the trailing and leading legs. The analysis was performed using a mixed effects model (fixed and random effects), which is used for data analysis when an individual’s responses are clustered and the assumption of independence among the findings within the same group is not adequately met [28]. The factors condition (with or without bandage) and legs (trailing or leading legs) were considered to be independent variables and were the fixed effects of the model. The variables total stance, braking, propulsive period, passive peak, time to passive peak, minimum between peaks, time to minimum between peaks, active peak, time to active peak, braking peak, time to braking peak, propulsive peak, time to propulsive peak, and braking and propulsive impulses were considered to be dependent, and a model was constructed for each response variable. The repeated measures of each individual were considered to be random effects in the model. The comparison between the means of the dependent variables was performed using orthogonal contrasts, which is a method based on Student’s t-test that allows for the calculation of confidence intervals for the differences between means. The mixed effects linear model requires that its residuals (expected value minus observed value) exhibit a normal distribution, with a zero mean and constant variance. Whenever this assumption was not met, logarithmic transformation was performed for the response variable. The model was fitted using the PROC R MIXED procedure of software SAS 9.1. The differences in the comparison analysis were considered to be statistically significant when the P value was less than 0.05.

694 K.S. Pegoretti et al. / Additional sensory input improves the strategy of stepping over obstacle in individuals with knee osteoarthritis Table 2 Variables for the vertical and AP force-time curves for the trailing leg: means (standard error) in the conditions with and without bandage, followed by the corresponding P values. BW: normalized by the body weight Variables for the vertical and AP force-time curves Passive Peak (BW) Time to Passive Peak (s) Passive Impulse (BWs) Minimum between the Peaks (BW) Time to a Minimum Between the Peaks (s) Active Peak (BW) Time to Active Peak (s) Active Impulse (BWs) Braking Peak (BW) Time to Braking Peak (s) Braking Impulse (BWs) Propulsive Peak (BW) Time to Propulsive Peak (s) Propulsive Impulse (BWs) Support Time (s) Braking Time (s) Propulsive Time (s) #

With bandage 1.05 (0.08) 0.82 (0.53) 0.72 (0.32) 0.88 (0.06) 1.20 (0.70) 1.07 (0.04) 1.50 (0.74) 0.80 (0.49) −0.06 (0.02) 0.41 (0.20) −0.04 (0.02) 0.13 (0.02) 1.72 (0.88) 0.06 (0.01) 2.12 (1.08) 1.08 (0.56) 1.04 (0.66)

Without bandage 1.07 (0.03) 0.87 (0.61) 0.74 (0.44) 0.88 (0.06) 1.26 (0.85) 1.07 (0.04) 1.58 (0.86) 0.87 (0.60) −0.06 (0.01) 0.42 (0.28) −0.03 (0.02) 0.13 (0.03) 1.81 (1.07) 0.06 (0.02) 2.23 (1.36) 1.10 (0.65) 1.14 (0.82)

P value 0.041# 0.256 0.765 0.722 0.184 0.201 0.041# 0.043# 0.368 0.724 0.724 0.662 0.042# 0.105 0.054 0.782 0.025#

Values with statistical difference between the conditions with and without bandage.

3. Results The results indicate that the use of bandage did not affect the pain parameters, as there was no significant difference between the values measured prior to the beginning of the obstacle-crossing protocol [2.73 (2.27); CI: 1.77–3.78], after the sixth attempt [3.34 (2.66); CI: 2.22–4.47], or at the end of the protocol [3.31 (2.46); CI: 2.28–4.45]. The analysis of the GRF-related variables indicated certain significant differences between conditions with and without the bandages (Table 2). With respect to the trailing leg, the duration of the propulsive period was significantly reduced (P < 0.05), and the duration of the total stance period exhibited a decreasing trend with the use of a bandage. The vertical component variables of passive peak, time to active peak, active impulse, and the anterior-posterior component variable time to propulsive peak were significantly decreased for the condition with the bandage compared to the condition without the bandage. With respect to the leading leg, increased braking peak in the condition with the bandage compared to that without the bandage was the only observed significant difference (Table 3).

4. Discussion The initial hypothesis of the present study was that the addition of sensory information would alter the

force, time, and impulse parameters of the vertical and anterior-posterior components of the ground reaction force. The findings confirmed these hypotheses, although the majority of the significant data concerned the trailing leg, i.e., the leg that contacted the platform before reaching the obstacle. In this regard, the first finding of interest was the reduction in the passive peak under the condition with the use of the bandage. The passive peak represents the acceptance of the body weight by the trailing leg immediately following contact of the foot with the ground, when the weight is passively received by the body [29,30]. Therefore, the addition of sensory information decreases the passive peak, indicating a reduction in the overload of the locomotor system when the foot contacts the ground. A similar result was reported in a recent study, which used a neoprene knee sleeve during unobstructed gait [19]. In this previous study, there was a decrease in the parameters of knee joint overload, which was associated with significant reduction in the co-contraction of the quadriceps muscle and the hamstring during the stance phase of gait. The altered pattern of knee motor control represented by muscle co-contraction appears to be a strategy employed by individuals with knee OA to increase joint stability, which is affected by the disease [31]. Therefore, tactile sensory information in the knee area may increase joint stability and thus contribute to the reduction of the impact of the foot’s contact with the ground during gait. The reduction in the passive peak that was induced by the use of bandage may represent a significant ben-

K.S. Pegoretti et al. / Additional sensory input improves the strategy of stepping over obstacle in individuals with knee osteoarthritis 695 Table 3 Variables for the vertical and AP force-time curves for the leading leg: means (standard error) in the conditions with and without bandage, followed by the corresponding P values. BW: normalized by the body weight Variables for the vertical and AP force-time curves Passive Peak (BW) Time to Passive Peak (s) Passive Impulse (BWs) Minimum between the Peaks (BW) Time to a Minimum Between the Peaks (s) Active Peak (BW) Time to Active Peak (s) Active Impulse (BWs) Braking Peak (BW) Time to Braking Peak (s) Braking Impulse (BWs) Propulsive Peak (BW) Time to Propulsive Peak (s) Propulsive Impulse (BWs) Support Time (s) Braking Time (s) Propulsive Time (s) # Values

With bandage 1.03 (0.07) 0.71 (0.57) 0.86 (0.51) 0.89 (0.11) 1.01 (0.67) 1.06 (0.03) 1.40 (0.83) 0.57 (0.30) −0.106 (0.02) 0.37 (0.18) −0.06 (0.03) 0.08 (0.02) 1.62 (1.01) 0.03 (0.01) 2.04 (1.15) 1.20 (0.78) 0.84 (0.43)

Without bandage 1.03 (0.06) 0.78 (0.61) 0.85 (0.47) 0.90 (0.09) 1.05 (0.67) 1.06 (0.03) 1.43 (0.78) 0.60 (0.32) −0.10 (0.02) 0.37 (0.17) −0.06 (0.03) 0.08 (0.02) 1.65 (0.96) 0.03 (0.01) 2.08 (1.16) 1.21 (0.77) 0.88 (0.46)

P value 0.398 0.092 0.793 0.216 0.376 0.480 0.223 0.105 0.033# 0.977 0.601 0.081 0.164 0.990 0.304 0.718 0.266

with statistical difference between the conditions with and without bandage.

efit in knee OA given in that it reduces joint overload, which is closely related to the progression of the disease. Increased knee adduction moment is a wellknown marker of OA severity and exhibits a strong correlation with the condition’s progression [32]. Therefore, interventions aiming to reducing the magnitude of the GRF or the distance between its force vector and the knee joint center may effectively reduce the knee adduction moment and, consequently, the overload on the medial compartment, thus delaying the progression of knee OA [33]. In this regard, additional sensory information as applied in the present study may contribute to the reduction in this type of medial compartment overload in individuals with knee OA by reducing the passive peak. Such an approach may therefore be applied to the rehabilitation of gait in patients with knee OA, especially in the early or acute phases of physical therapy. The results of the time variables indicate a reduction in the time the foot is in contact with the ground with the use of bandage, especially in the propulsive phase. Taken together, these results suggest that the addition of sensory information facilitates the obstaclecrossing task, as the same movement was performed in less time. Increase in movement speed is generally followed by a reduction in the time the foot is in contact with the ground, as well as by the greater degree of ground force against the foot [34,35]. In the present study, however, although the contact time decreased with the use of bandage, the ground force did not increase.

Young individuals generate enlarged force in the propulsive phase with increased obstacle height [36], whereas the force magnitude did not vary in older adults without any associated disease [35]. However, following training using protocols to increase the muscle strength, older adults exhibited a significant increase in the peak ground reaction forces [37]. These previous findings suggest that the significant reduction in the muscle strength and power due to knee OA, associated with an improvement in the quality and representation of sensory information achieved by the use of bandage, leads to a motor strategy that imposes fewer functional demands on the musculoskeletal and neuromuscular systems when performing the same task, an effect that manifested in this case as a lower active impulse. Therefore, it may be recommended for patients with knee OA to use bandages, especially during functional training for muscle rehabilitation. The use of a bandage results in additional sensory information given that it may increase the tactile stimulation of the skin and deep pressure receptors [38]. The bandage that was used in the present study may stimulate the skin phasic receptors through the stretching of the skin during motion. Such greater peripheral stimulation may increase the flow of sensory information that reaches the higher somatosensory centers, thus allowing for improved perception of the joint position and body in space. This improved quality of sensory information contributes to more efficient motor control, leading to more rapid movements and less generation of force.

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The integration of the vibrotactile information supplied to the skin surface was recently demonstrated to occur primarily through a process of “sensory addition”, as opposed to a process of “sensory substitution” [39]. Skin-adherent tactile information is treated by the posture control system as a natural sensory cue that reduces the system noise when it is present [40]. Thus, stimulation provided by the bandage does not replace the proprioceptive information that is lost as a result of knee OA but adds novel information that may be used to improve posture control for the duration of the stimulus, thus characterizing a process of sensory addition. The effect of sensory addition becomes more relevant in rehabilitation when treatment aims to achieve functional recovery independently from external resources. In this regard, the additional tactile information that was used in the present study must be applied in treatments that also focus on motor relearning. It was hypothesized that pain may decrease as a function of the addition of sensory information, as this was the most frequent finding of studies using bandages, tape, and braces [8,41]. However, the findings indicated that the supply of additional sensory information did not alter pain parameters, suggesting that the improvement in GRF control cannot be associated with a reduction in pain.

4.2. Clinical implications The improvement of the GRF-related biomechanical parameters that were observed in the present study may provide a sound basis for the use of devices that add tactile sensory information for the rehabilitation of patients with knee OA. Such devices may be included in therapeutic interventions, primarily during the early stages of the rehabilitation for functional tasks given that these devices increase the efficiency of motion and may also facilitate the process of motor relearning.

5. Conclusion The use of a bandage as an additional source of sensory information, represented as a tactile stimulus adhered to the skin of the knee, improved GRF-related biomechanical parameters during the obstacle-crossing task in individuals with knee OA. These findings indicate a decreased overload during the phase of body weight acceptance, better estimates of the impulse required for the propulsion of the center of mass, and a more rapid accomplishment of the task. However, the addition of sensory information did not affect pain parameters.

Acknowledgements 4.1. Study limitations Although the use of a single force plate allowed for the investigation of the GRF in the trailing and leading legs at various stages of the gait cycle, this approach did not allow for the collection of data regarding the continuous movement of obstacle crossing, which requires the placement of force plates before and after the obstacle. This limitation prevents a thorough discussion of the braking peak increase that was observed in the leading leg with the use of bandage. The magnitude of this peak, which occurs in the first half of the stance phase, results from the backward friction force and represents the force required to decelerate immediately after the foot contacts the ground [29,30]. One may suggest that motion was more rapid in the presence of additional sensory information, especially during the propulsive phase of the supporting leg. This effect would have resulted in the requirement to increase anterior-posterior braking to ensure the maintenance of the dynamic balance and of movement through the transposition of the trailing leg. However, due to study limitations, this hypothesis could not be confirmed.

The authors would like to thank the physiotherapy service at the Rehabilitation Center, Hospital das Clínicas of Ribeirão Preto Medical School, for allowing us to select and assess the volunteers with knee osteoarthritis in the hospital facility.

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