Arthroscopy is a modern surgical technique that allows the internal exploration and operation of a joint without cutting, but rather penetrating the joint with very thin probes and instruments through small holes with a diameter of 7/8 mm. The main advantages offered by this method, compared to the traditional one, are: view of all the elements that are found within the joint; no need for immobilisation after the operation; less post-operative pain; rapid rehabilitation of the movement; shorter hospitalisation period for the operation; shorter convalescence; lower complication occurrence (infections, thrombophlebitis, etc.) aesthetic damages are reduced to the minimum; the opportunity to perform high precision surgery that allows the treatment of the lesion only, respecting the nearby tissues, or even just the damaged part of that same tissue (for example, the meniscus). The trauma due to surgery is therefore minimized and movement of the joint will almost be completely regained a few days after the operation; the rehabilitation of the muscular strength is a more difficult process, since the muscles are indirectly weakened by the ailments caused by the lesion (meniscal, cartilaginous, ligamental) and the surgery. Therefore, the patient will receive a detailed program including the description and the explanation of all the exercises that need to be done the following days. After the operation, which can be performed in either total or peripheral anaesthesia, the limb is bandaged and, that very same afternoon, the patient can begin the first re-habilitation exercises. From January 2002, knee arthroscopy is performed with Surgical Day Hospital procedures, and the patient can usually leave the hospital the very same evening of the operation. Bandages are kept until the first medication, which is done 4-5 days after the operation through an appointment made by the ward secretary when the patient leaves the hospital. When at home, the patient needs to follow the rehabilitation program from the very first day. Often, in order to achieve full muscular strength rehabilitation, the assistance of a Physiotherapy Center is needed. Right from the day following the operation, the patient can walk using crutches by loading half of his body weight on the other leg when making steps. The crutches are used for 5-7 days, until the remission of painful symptoms. The first few days after the operation the knee is likely to swell: ice needs to be applied regularly every 20 minutes at least 4-5 times a day, always after physical exercises. When resting, the leg needs to be kept in a lifted position, and the patient should not stand still for a long time, as this would increase the swelling. Recovery times vary according to the pathology treated: for the removal of a single meniscus the patient may need between 3 and 4 weeks. In case of cartilage lesions the patient may need several weeks (up to 4-5 months in the most serious cases). For the reconstruction of one of the ligaments the patient may need up to several months. POSSIBLE COMPLICATIONS LINKED TO THE ARTHROSCOPY OF THE KNEE 1.   PROMINENT AND PERSISTENT SWELLING: this is a minor complication that can be solved through constant ice applications and increased rest; sometimes, it might be necessary to drain the liquid with a syringe (ARTHROCENTESIS). 2.   INFECTION: the signs are high fever and pulsing pain. The hospital must be alerted immediately: an examination will be done and after draining the fluid that might be present inside the knee, the patient will be put on an antibiotic therapy. An arthroscopy washing of the joint might be necessary if after two weeks of therapy no improvement is observed. Although very rare, this is a very dangerous complication that could jeopardize a successful operation and the complete rehabilitation of the joint. 3.   HROMBOPHLEBITIS OF THE DEEP VEINS OF THE LEG: it indicates the inflammation of the veins of the operated leg (seldom of the other one). The signs are the tumefaction of the foot and leg, a strong sense of heaviness of the limb and calf pain. In order to decrease the occurrence of such complication, it is necessary to carefully follow the heparin therapy recommended when discharged from the hospital, to avoid standing still for a long time, to start the rehabilitation therapy as soon as possible and follow it consistently. 4.   PULMONAR EMBOLISM: it indicates the detachment of a thrombus that developed in one of the veins as a consequence of the previously described complication. The thrombus reaches the lungs and causes chest pain, difficulties in breathing, cough, sometimes bronchial catarrh containing a little bit of blood. This is a dreadful and very dangerous complication that requires immediate hospitalisation in an internal medicine ward. In order to prevent such complication from arising, the same preventive measures for complication n°3 need to be followed. 5.   THE BREAKING OF SURGICAL INSTRUMENTS INSIDE THE JOINT: this is a very rare complication that most of the times can be solved by simply removing the broken metal piece by using magnetic cannulas in arthroscopy. However, sometimes it might be necessary to surgically open the joint in order to remove the broken fragment.