Forty patients with chronic KOA in HILT group will received Class IV LASER therapy. A Class IV LASER emits power more than 500 milliwatt (mW) .

Patients with chronic KOA in ibuprofen gel phonophoresis (IGP) group will administered with continuous ultrasound set at a frequency of 1 megahertz (MHz) and an intensity of 1 W/cm2 was applied on a circular basis.

Fourty patients with chronic KOA will receive structured tDCS (MA-tDCS, Walnut-Medical, Johnstown, PA) treatment. Two pair of sponge electrodes soaked with saline and fixed to head with elastic bands. The transcranial direct current stimulation will be applied by a constant current device with an intensity of 2mA

Individual with chronic KOA will be educated on how to do the set of exercises correctly at their home during the first session. All the groups will receive the same, standardized exercise protocol for KOA which consisted of nine exercises including muscle strengthening and flexibility training.

The total energy will be delivered to the patient during one session will be 1,250 J through three phases of treatment.

1. Initial phase (710 and 810 mJ (millijoule)/cm2 for a total of 500 J)
2. Intermediate phase (handpiece will be applied on the joint line just proximal to the medial and lateral tibial condyles with 25 J, a fluency of 610 mJ/cm2, and a time of 14 s for each point and a total of 250 J)
3. Final phase (same as the initial phase (500 J) except that scanning will be slow manual scanning ) The application time for all three phases will be approximately 15 min with the total energy delivered to the patient during one session of 1,250 J

Pain intensity will be measured using calibrated digitalized pain pressure algometer (ALGO-DS-01) in patients with KOA. Sensor digital algometer is force gauge with computer size which is highly accurate. The ALGO-DS-01 is chosen for the assessment of pain for Mechanical sacroiliac joint dysfunction, which is a reliable and valid tool for assessing sacroiliac joint dysfunction. The inter rater reliability of pressure pain algometer was demonstrated to be moderate to good reliability with interclass correlation coefficient (ICC) of (0.62-0.84)

The Western Ontario and Mc Master Universities Osteoarthritis Index (WOMAC) will be was used to evaluate the disease-specific self-reported symptoms of OA.48 This form is comprised of 24 questions in three categories including pain (5 questions), stiffness (2 questions), and physical function (17 questions). These 24 items are presented in a five-point Likert (0-4) scale, where higher scores indicate the higher intensity of the related symptom. The minimal clinical important difference of WOMAC at 2 month of intervention is found to be, 14.1 The WOMAC measures five items for pain (score range 0-20), two for stiffness (score range 0-8), and 17 for functional limitation (score range 0-68). Higher scores on the WOMAC indicate worse pain, stiffness, and functional limitations.

The 36-Item Short Form Health Survey questionnaire (SF-36) is a very popular instrument for evaluating Health-Related Quality of Life (QoL). The SF-36 measures eight scales: physical functioning (PF), role physical (RP), bodily pain (BP), general health (GH), vitality (VT), social functioning (SF), role emotional (RE), and mental health (MH). There are two distinct concepts measured by the SF-36: a physical dimension, represented by the Physical Component Summary (PCS), and a mental dimension, represented by the Mental Component Summary (MCS). SF-36 is used to assess QoL in patient with KOA.

The lower the score the more disability. The higher the score the less disability i.e., a score of zero is equivalent to maximum disability and a score of 100 is equivalent to no disability.