As life expectancy increases, more and more people are afflicted with degenerative joint diseases. Knee osteoarthritis is a pathology typical of old age (over 60 years), but it can also occur in younger people (aged 40-50 years) and is more prevalent in women (11%) than men (7%). Total knee replacement surgery is becoming increasingly frequent.In the immediate post-operative period, the main problems encountered by patients are: inflammation, edema and, above all, pain. These can strongly influence the restoring of a correct muscle-joint function and hence the time needed for a return to normal activities of daily living (ADLs).Post-operative rehabilitation is now a fundamental part of the functional recovery of patients after knee replacement surgery. Traditional rehabilitation programs are mainly focused on improving joint mobility, reducing musculotendinous retractions, increasing muscle strength and establishing a correct gait pattern. Over the years, in addition to the manual rehabilitative techniques, the use of instrumental methods to stimulate the healing processes and speed up recovery times has become a frequent practice, especially for the management of post-operative pain and inflammation. One of these methods is laser therapy, which consists of light radiation composed of a beam of photons with specific physical characteristics that interacts with living tissue to produce an anti-inflammatory, analgesic and biostimulation effect. Another form of instrumental therapy used in rehabilitation for the management of pain/edema resulting from an inflammatory process is the application of cold (cryotherapy) or heat (thermotherapy) or both together in combination (contrast therapy). Cryotherapy is a type of physical therapy that produces temporary anesthesia of the part undergoing treatment.Thermotherapy consists of the application of heat to stimulate a biological process inducing the release of chemotactic substances and growth factors, which have a powerful regenerative and reparative action. An innovative device that combines the therapeutic advantages of these different forms of physical therapy is QMD Helios (Hakomed, Egna, BZ, Italy), designed to provide cryo-thermal and laser treatment. The device is equipped with a high-power diode laser. This therapeutic laser can work at 3 different wavelengths (808 nm,1064 nm, 1120 nm). The wavelengths are each individually controlled and can be delivered in various modes: continuous wave, pulsed mode, super pulse, and Harmonic pulsation (laser wave emission with a variable frequency - determined by means of a scan performed by the device - suited to the tissue to be treated). This innovative triple-wavelength emission represents the most versatile solution when one wishes to obtain different therapeutic effects at the same time. In addition to the use of laser, the device allows the application of cryo-thermal therapy, simultaneously or separately. Simultaneous administration promotes thermal shock, a basic principle of contrast therapy characterized by a marked variation of temperature (30-40 degrees) within a short space of time (30-60 seconds) inducing vasodilation through the heat and vasoconstriction through the cold. Thermal shock is effective in the early stages of rehabilitation for a rapid resolution of pain and swelling.Although in recent years instrumental therapy has come to play a very important role in rehabilitation medicine in the management of pain/inflammation in the acute patient, there is lack of reported evidence in the literature on the use of laser therapy in patients after knee replacement surgery. The aim of this study is to evaluate the effectiveness of the use of the QMD Helios laser device in association with standard rehabilitation therapy in reducing edema and pain symptoms in patients following total knee replacement.