A PT modality is a type of electrical, thermal or mechanical energy that causes physiological changes. These modalities includes ultrasound, LASER, shockwave, trancutaneous electrical nerve stimulation (TENS), electrical stimulation, hot packs, cold packs, paraffin, IRR and traction. Some of the functions of these modalities are to relieve pain, improve circulation, decrease swelling and reduce muscle spasm in conjuction with other treatments like exercises. Application of these modalities needs a thorough assessment first to check for any contraindications and to know which modality is beneficial for the patient.