The Effect of Cryotherapy in Pain Control, Function and Quality of Life in Individuals With Knee Osteoarthritis

A thermographic camera will be used (FLIR Systems Inc. model T-420) integrated with a real resolution of 320x240 pixels, sensors for measuring temperatures ranging from -20 °C (Celsius) to + 1200 °C and with a lower sensitivity to detect temperature differences of 0,08 ºC with ± 2°C of absolute temperature measurement, according to manufacturer's specifications (FLIR Systems Inc., 2006).

The thermographic evaluation will be conducted in a controlled environment (21 °C ± 2 °C), with fluorescent lighting and a black background for the photos. Individuals will be advised not to bathe, perform physical exercise or use metabolic stimulants and decongestants 2 hours before the test, because these procedures affect the bloodstream and consequently the thermal images of interest. They will also be instructed not to use topical products like creams, powders or sprays on the area to be evaluated.

To measure the pressure pain threshold, it will be used a digital algometry of mechanical pressure (ITO Co., limited company (LTD)- Physiotherapy \& Rehabilitation, OE-220 model, TOKYO, Japan) with a contact area of 1cm2. It will be performed 03 consecutive measurements (with an interval of 20s between each measurement) in 12 predetermined points chosen randomly. It will be used the average value of the 03 measurements (kg/s). At each point, the pressure pain threshold will be evaluated by applying the tip of a algometer at a speed of 1 kilogram per second, perpendicularly. The speed is controlled by the evaluator through the digital instrument display and the individual will receive a remote control with guidance to activate it at the exact moment that the pressure made by the algometry becomes painful. The interval time between each measurement will be observed to avoid temporal summation of cutaneous nociceptors.

All volunteers will answer to the questionnaire before and 1 day after the intervention. WOMAC is a self-report questionnaire designed to assess the problems experienced by people with OA of the lower limb. The score for the items is expressed through a Likert scale, where the rating is calculated as: none = 0, low = 25 = 50 moderate, severe = 75 and very severe = 100. The maximum score on each section is expressed as a percentage, with higher scores indicating greater pain, stiffness and physical dysfunction. Each point corresponds to a particular dimension (pain, stiffness and physical function). This questionnaire has been translated and validated for the Portuguese language from Brazil.

All volunteers will answer to the questionnaire before and 1 day after the intervention. KOOS is a specific questionnaire which consists of 42 items divided into 5 subscales. It is self-administrative and aims to measure the quality of life and knee function evaluating five indicators: pain, other symptoms, function in daily life, function related to sports and recreation, and quality of life related to the knee. The answers are standardized (5 options for each question) and each question has a score ranging from 0 to 4. The initial score is transformed into a scale from 0 to 100, calculated for each subscale, so that higher values indicate better functionality and lower, a worse condition. It is also validated for the Portuguese language with acceptable psychometric characteristics when compared to the original one.

All volunteers will conduct the test before and 1 day after the intervention. TUG is a test that evaluates the balance of the individual in the sitting position, in sitting to standing transfers, stability in ambulation and gait course changes without the use of compensatory strategies. The test consists of asking the individual to stand from a chair, walk 3 meters, turn around, go back and sit back in the chair. The timing of the test is used as a functionally independent predictor: a time below 20 seconds is considered normal and above 30 seconds is considered as a possible increased risk of falls and functional dependency. It is estimated also the ability to get up, balance, posture, the base of gait (wide or short), the start of the march (if there is hesitation or freezing), speed, step size, continuity, symmetry, balance of the trunk and limbs, involuntary movements and the ability to return.

All volunteers performed the test before and 1 day after the intervention. The 30 seconds chair stand test is administered using an armless chair, with seat height of about 43cm from the ground. The chair has a rubber for not slipping under its support and is placed against a wall to avoid oscillations. The participant sits in the middle of the chair with the back straight, feet apart, aligned with the shoulder width apart and flat on the floor at an angle slightly behind the knee line. Moreover, to help maintain balance, one foot may be slightly placed ahead of the other and arms crossed against the chest. The test consists of the greatest number of times from a sitting position to a standing over a period of 30 seconds. Thus, it is possible to evaluate a wide range of skill levels with scores ranging from 0, for those who cannot complete a single repetition and values greater than 20 reps for the well prepared individuals.