A therapeutic pain education program for patients will be implemented. There will be four 30-minute face-to-face sessions (one session per week). The objective is to change the participants' conceptualization of pain. From seeing pain as a marker of tissue damage to a marker of the body's perceived need for protection. Contents include basic structure of the nervous system, distinction between nociception and pain, peripheral and central sensitization, neuroplasticity and benefits of exercise.

A TENS (100 Hz 100 ms) current will be applied through four needles located in the knee for 30 minutes. Eight sessions will be held during a month (two per week). The distribution of the channels will be for the first channel anode in lateral anterior zone and cathode in medial anterior zone and for the second channel anode in Hoffa's fat and cathode in goose foot. Participants will be able to adjust the amplitude to a strong and manageable sensory stimulation intensity that was not strong enough to cause muscle contraction.

A TENS (100 Hz 100 ms) current will be applied through four patches located in the knee for 30 minutes. Eight sessions will be held during a month (two per week). The distribution of the channels will be for the first channel anode in lateral anterior zone and cathode in medial anterior zone and for the second channel anode in Hoffa's fat and cathode in goose foot. Participants will be able to adjust the amplitude to a strong and manageable sensory stimulation intensity that was not strong enough to cause muscle contraction.

To perform the dry needling placebo, modified needles will be used according to the validation performed by Mitchell et al. 2018, since they generate more puncture sensation than normal needles, which has been shown to generate more analgesia and to be more effective as a placebo. To perform placebo TENS, the protocol established by Rakel et al. 2010 will be used, which consists of applying a TENS of 100 Hz and 100 ms for 30 seconds and then lowering the intensity during the following 15 seconds. Eight sessions will be held during a month (two per week).

The visual analogue scale (VAS) uses a 10 cm line with endpoint descriptors such as 'no pain' marked at the left end of the line and 'worst pain imaginable' marked at the right end. Patients are asked to mark a point on the line that best represents their pain.

The visual analogue scale (VAS) uses a 10 cm line with endpoint descriptors such as 'no pain' marked at the left end of the line and 'worst pain imaginable' marked at the right end. Patients are asked to mark a point on the line that best represents their pain.

Pressure Pain Threshold (PPT) will be assessed at thumb, trapezius superior muscle, tibialis anterior muscle and patella using a digital algometer (Wagner instruments, Greenwich, CT, USA). Participants will be instructed to say "stop" when the pressure sensation becomes painful. The average of two trials for each side will be performed for analysis. The algometer pressure for assessment will be gradually increased at a rate of 1kg/second. Data will be collected in kg/cm2.

Pressure Pain Threshold (PPT) will be assessed at thumb, trapezius superior muscle, tibialis anterior muscle and patella using a digital algometer (Wagner instruments, Greenwich, CT, USA). Participants will be instructed to say "stop" when the pressure sensation becomes painful. The average of two trials for each side will be performed for analysis. The algometer pressure for assessment will be gradually increased at a rate of 1kg/second. Data will be collected in kg/cm2.

Pressure Pain Threshold (PPT) will be assessed at thumb, trapezius superior muscle, tibialis anterior muscle and patella using a digital algometer (Wagner instruments, Greenwich, CT, USA). Participants will be instructed to say "stop" when the pressure sensation becomes painful. The average of two trials for each side will be performed for analysis. The algometer pressure for assessment will be gradually increased at a rate of 1kg/second. Data will be collected in kg/cm2.

Conditioned pain modulation (CPM) is a centrally processed measure of the net effect of the descending pain pathway. A digital algometer will be used for the test stimulus and a pressure cuff will be used for the conditioned stimulus. Pain intensity will be measured with the numeric rating scale (NRS).

Conditioned pain modulation (CPM) is a centrally processed measure of the net effect of the descending pain pathway. A digital algometer will be used for the test stimulus and a pressure cuff will be used for the conditioned stimulus. Pain intensity will be measured with the numeric rating scale (NRS).

Conditioned pain modulation (CPM) is a centrally processed measure of the net effect of the descending pain pathway. A digital algometer will be used for the test stimulus and a pressure cuff will be used for the conditioned stimulus. Pain intensity will be measured with the numeric rating scale (NRS).

Conditioned pain modulation (CPM) is a centrally processed measure of the net effect of the descending pain pathway. A digital algometer will be used for the test stimulus and a pressure cuff will be used for the conditioned stimulus. Pain intensity will be measured with the numeric rating scale (NRS).

Temporal summation of pain (TSP) is a noninvasive and indirect measure of central sensitization in humans, which refers to an increase in pain intensity with repetitive noxious stimuli. An Algometer will be used to induce temporal summation. It will be applied vertically, directly on the thumb on the asymptomatic side, stimulating 10 consecutive times for 1 second and with 1 second intervals with a previously determined pressure. The results will be obtained by the difference between the first and the tenth measurement of pain intensity.

Temporal summation of pain (TSP) is a noninvasive and indirect measure of central sensitization in humans, which refers to an increase in pain intensity with repetitive noxious stimuli. An Algometer will be used to induce temporal summation. It will be applied vertically, directly on the thumb on the asymptomatic side, stimulating 10 consecutive times for 1 second and with 1 second intervals with a previously determined pressure. The results will be obtained by the difference between the first and the tenth measurement of pain intensity.

Temporal summation of pain (TSP) is a noninvasive and indirect measure of central sensitization in humans, which refers to an increase in pain intensity with repetitive noxious stimuli. An Algometer will be used to induce temporal summation. It will be applied vertically, directly on the thumb on the asymptomatic side, stimulating 10 consecutive times for 1 second and with 1 second intervals with a previously determined pressure. The results will be obtained by the difference between the first and the tenth measurement of pain intensity.

Temporal summation of pain (TSP) is a noninvasive and indirect measure of central sensitization in humans, which refers to an increase in pain intensity with repetitive noxious stimuli. An Algometer will be used to induce temporal summation. It will be applied vertically, directly on the thumb on the asymptomatic side, stimulating 10 consecutive times for 1 second and with 1 second intervals with a previously determined pressure. The results will be obtained by the difference between the first and the tenth measurement of pain intensity.

The Timed Up and Go (TUG) Test is a test especially indicated to measure mobility and assess the risk of falls in the elderly. The patient will begin sitting in a chair with his back supported and his arms on the armrests, when he hears the word "Let's go" he must get up and walk to a mark that will be on the ground 3 meters away and finally the person will turn around and walk again to sit on the chair. The time it takes from when you say "Let's go" until he sits down again will be timed (3 attempts and the results are averaged).

The Timed Up and Go (TUG) Test is a test especially indicated to measure mobility and assess the risk of falls in the elderly. The patient will begin sitting in a chair with his back supported and his arms on the armrests, when he hears the word "Let's go" he must get up and walk to a mark that will be on the ground 3 meters away and finally the person will turn around and walk again to sit on the chair. The time it takes from when you say "Let's go" until he sits down again will be timed (3 attempts and the results are averaged).

The Timed Up and Go (TUG) Test is a test especially indicated to measure mobility and assess the risk of falls in the elderly. The patient will begin sitting in a chair with his back supported and his arms on the armrests, when he hears the word "Let's go" he must get up and walk to a mark that will be on the ground 3 meters away and finally the person will turn around and walk again to sit on the chair. The time it takes from when you say "Let's go" until he sits down again will be timed (3 attempts and the results are averaged).

Pain severity will be assessed using the Spanish version of the Chronic Pain Grading Scale (GCPS). This scale is a self-reported instrument that consists of two subscales; the first assesses pain intensity, and the second assesses perceived disability. The scale is made up of a total of 8 items, 7 of which are 11 points in Likert format, and the other item assesses the perpetuation of pain, asking for the number of days of pain in the previous 6 months. The Spanish version of the GCPS has proven to be a valid and reliable instrument to assess the severity of chronic pain.

Pain severity will be assessed using the Spanish version of the Chronic Pain Grading Scale (GCPS). This scale is a self-reported instrument that consists of two subscales; the first assesses pain intensity, and the second assesses perceived disability. The scale is made up of a total of 8 items, 7 of which are 11 points in Likert format, and the other item assesses the perpetuation of pain, asking for the number of days of pain in the previous 6 months. The Spanish version of the GCPS has proven to be a valid and reliable instrument to assess the severity of chronic pain.

Pain severity will be assessed using the Spanish version of the Chronic Pain Grading Scale (GCPS). This scale is a self-reported instrument that consists of two subscales; the first assesses pain intensity, and the second assesses perceived disability. The scale is made up of a total of 8 items, 7 of which are 11 points in Likert format, and the other item assesses the perpetuation of pain, asking for the number of days of pain in the previous 6 months. The Spanish version of the GCPS has proven to be a valid and reliable instrument to assess the severity of chronic pain.

MEC is the spanish version of the Mini-Mental Status Examination. It is the most widely used cognitive screening test to assess suspected symptoms compatible with cognitive impairment or dementia. Through a series of questions and requests, different cognitive functions are evaluated: temporal and spatial orientation, immediate memory, information storage and retrieval, concentration and working memory, oral language, reading and writing a sentence and visoconstruction by copying a simple drawing.

The State-Trait Anxiety Inventory (STAI). This questionnaire comprises two subsections of 20 items each for the measurement of anxiety as a state and as a trait, with a 4-point Likert-type response (0: not at all; 3: very much). Scores range from 0 to 60 points, with higher scores indicating greater anxiety.

The State-Trait Anxiety Inventory (STAI). This questionnaire comprises two subsections of 20 items each for the measurement of anxiety as a state and as a trait, with a 4-point Likert-type response (0: not at all; 3: very much). Scores range from 0 to 60 points, with higher scores indicating greater anxiety.

The State-Trait Anxiety Inventory (STAI). This questionnaire comprises two subsections of 20 items each for the measurement of anxiety as a state and as a trait, with a 4-point Likert-type response (0: not at all; 3: very much). Scores range from 0 to 60 points, with higher scores indicating greater anxiety.

Beck Depression Inventory-II (BDI-II) is a self-report measure of depression in a variety of settings and populations. It is the most widely used questionnaire worldwide to assess depression. The total score ranges from 0 to 63 points. A change of 5 points corresponds to a minimally important clinical difference.

Beck Depression Inventory-II (BDI-II) is a self-report measure of depression in a variety of settings and populations. It is the most widely used questionnaire worldwide to assess depression. The total score ranges from 0 to 63 points. A change of 5 points corresponds to a minimally important clinical difference.

Beck Depression Inventory-II (BDI-II) is a self-report measure of depression in a variety of settings and populations. It is the most widely used questionnaire worldwide to assess depression. The total score ranges from 0 to 63 points. A change of 5 points corresponds to a minimally important clinical difference.

The Spanish version of the Pain Catastrophizing Scale (PCS) it has 13 items and each one is rated on a 5-point scale: 0 (not at all) to 4 (all the time). It comprises 3 dimensions: rumination, magnification, and despair. The theoretical range of the instrument is between 13 and 62, with low scores indicating low catastrophism and high values indicating high catastrophism.

The Spanish version of the Pain Catastrophizing Scale (PCS) it has 13 items and each one is rated on a 5-point scale: 0 (not at all) to 4 (all the time). It comprises 3 dimensions: rumination, magnification, and despair. The theoretical range of the instrument is between 13 and 62, with low scores indicating low catastrophism and high values indicating high catastrophism.

The Spanish version of the Pain Catastrophizing Scale (PCS) it has 13 items and each one is rated on a 5-point scale: 0 (not at all) to 4 (all the time). It comprises 3 dimensions: rumination, magnification, and despair. The theoretical range of the instrument is between 13 and 62, with low scores indicating low catastrophism and high values indicating high catastrophism.

Tampa Scale for Kinesiophobia (TSK-11) is an 11-item scale that assesses the degree of fear of movement and (re)injury. Each item is scored from 1 to 4 according to the degree of agreement with the statement (1: do not agree at all; 4: strongly agree). The validated Spanish version of the 11-item scale has a total score of 11 to 44 items and has two subscales: activity avoidance and harm.

Tampa Scale for Kinesiophobia (TSK-11) is an 11-item scale that assesses the degree of fear of movement and (re)injury. Each item is scored from 1 to 4 according to the degree of agreement with the statement (1: do not agree at all; 4: strongly agree). The validated Spanish version of the 11-item scale has a total score of 11 to 44 items and has two subscales: activity avoidance and harm.

Tampa Scale for Kinesiophobia (TSK-11) is an 11-item scale that assesses the degree of fear of movement and (re)injury. Each item is scored from 1 to 4 according to the degree of agreement with the statement (1: do not agree at all; 4: strongly agree). The validated Spanish version of the 11-item scale has a total score of 11 to 44 items and has two subscales: activity avoidance and harm.

In vivo catastrophism. Questions will be asked regarding the types of thoughts and feelings of the patient while the painful stimulus was applied in the measurement of conditioned pain modulation. Using the a scale, you are asked to indicate the degree to which you had these thoughts and feelings during the pain test.

Consumer Reports Effectiveness Scale (CRES-4) consisting of four items designed to evaluate whether patients are satisfied with the therapy they have received and if it has been perceived as effective or not. Its global score is intended to reflect treatment effectiveness as perceived by the patient.

Consumer Reports Effectiveness Scale (CRES-4) consisting of four items designed to evaluate whether patients are satisfied with the therapy they have received and if it has been perceived as effective or not. Its global score is intended to reflect treatment effectiveness as perceived by the patient.

Consumer Reports Effectiveness Scale (CRES-4) consisting of four items designed to evaluate whether patients are satisfied with the therapy they have received and if it has been perceived as effective or not. Its global score is intended to reflect treatment effectiveness as perceived by the patient.

The Global Rating of Change Score (GRoC) is a frequently used outcome measure that has been used to independently score self-perceived improvement in a patient and has been used as an anchor method to determine minimal clinically important change scores. The GRoC is a single-item, recall-based questionnaire of well-being that is based on progress (or lack of progress) since an initial treatment encounter.

The Global Rating of Change Score (GRoC) is a frequently used outcome measure that has been used to independently score self-perceived improvement in a patient and has been used as an anchor method to determine minimal clinically important change scores. The GRoC is a single-item, recall-based questionnaire of well-being that is based on progress (or lack of progress) since an initial treatment encounter.

The Global Rating of Change Score (GRoC) is a frequently used outcome measure that has been used to independently score self-perceived improvement in a patient and has been used as an anchor method to determine minimal clinically important change scores. The GRoC is a single-item, recall-based questionnaire of well-being that is based on progress (or lack of progress) since an initial treatment encounter.

Demographic information including sex, age, weight, height, pain duration, the mean and worse pain intensities during the last week using the Visual Analogue Scale will be collected.

Short physical performance battery (SPPB). It makes it possible to classify the level of physical functioning of the elderly throughout the entire functional spectrum. It consists of carrying out three tests: balance (in three positions: feet together, semi-tandem and tandem), gait speed (4 meters) and getting up and sitting down on a chair five times.The total SPPB score and outcome assessment results from the sum of the three subtests, and ranges from 0 (worst) to 12; changes of 1 point have clinical significance. A score below 10 indicates frailty and an elevated risk of disability as well as falls.

Short physical performance battery (SPPB). It makes it possible to classify the level of physical functioning of the elderly throughout the entire functional spectrum. It consists of carrying out three tests: balance (in three positions: feet together, semi-tandem and tandem), gait speed (4 meters) and getting up and sitting down on a chair five times. The total SPPB score and outcome assessment results from the sum of the three subtests, and ranges from 0 (worst) to 12; changes of 1 point have clinical significance. A score below 10 indicates frailty and an elevated risk of disability as well as falls.

Short physical performance battery (SPPB). It makes it possible to classify the level of physical functioning of the elderly throughout the entire functional spectrum. It consists of carrying out three tests: balance (in three positions: feet together, semi-tandem and tandem), gait speed (4 meters) and getting up and sitting down on a chair five times. The total SPPB score and outcome assessment results from the sum of the three subtests, and ranges from 0 (worst) to 12; changes of 1 point have clinical significance. A score below 10 indicates frailty and an elevated risk of disability as well as falls.

The SF-12 Health Survey (SF-12) is a 12-item questionnaire used to assess generic health outcomes from the patient's perspective. Generic patient-reported outcome measures like the SF-12 assess general health and well-being, including the impact of any and all illnesses on a broad range of functional domains. The response options form Likert-type scales (where the number of options varies from three to six points, depending on the item), which evaluate intensity and/or frequency of people's health status. The score ranges from 0 to 100, where the higher the score, the better the health-related quality of life.

The SF-12 Health Survey (SF-12) is a 12-item questionnaire used to assess generic health outcomes from the patient's perspective. Generic patient-reported outcome measures like the SF-12 assess general health and well-being, including the impact of any and all illnesses on a broad range of functional domains. The response options form Likert-type scales (where the number of options varies from three to six points, depending on the item), which evaluate intensity and/or frequency of people's health status. The score ranges from 0 to 100, where the higher the score, the better the health-related quality of life.

The SF-12 Health Survey (SF-12) is a 12-item questionnaire used to assess generic health outcomes from the patient's perspective. Generic patient-reported outcome measures like the SF-12 assess general health and well-being, including the impact of any and all illnesses on a broad range of functional domains. The response options form Likert-type scales (where the number of options varies from three to six points, depending on the item), which evaluate intensity and/or frequency of people's health status. The score ranges from 0 to 100, where the higher the score, the better the health-related quality of life.