Arthritis Clinical Trials

Introduction:

Approximately 7000 total knee replacements (TKAs) are done every year. More than 90% of these knee replacements are performed with the use of bone cement. Traditionally, a tourniquet has been, used to reduce the bleeding during surgery, enabling surgeons to perform delicate dissections in a bloodless operative field.

A tourniquet can be defined as a constricting or compressing device used to control temporarily venous and arterial circulation to an extremity. Pressure is applied circumferentially on the skin and underlying tissues of a limb. This pressure is transferred to the walls of vessels, causing them to become occluded.

It is well known that applying a tourniquet for more than 1 to 2 hours is associated with a number of disadvantages, for instance, severe pain and muscle effects during the first postoperative day, thereby slowing rehabilitation.

Other side effects related to tourniquet use, include pulmonary embolus caused by venous thrombosis and arterial thrombosis as a result of the dislodgement of an arterial plaque. Furthermore, tourniquet-induced hypertension with general anaesthesia, muscle injury, a wide spectrum of neurologic injuries, and tissue changes (Oedema compartment syndrome, post-tourniquet syndrome) have been reported. An important fact is that bleeding affects the quality of binding between bone and cement and thereby fixation of the knee prosthesis? Since the introduction of modern cementing techniques, no previous clinical studies have investigated the advantages or disadvantages of tourniquet use in knee replacement surgery.

Aims/hypothesis of the study:

1. To investigate the advantages and disadvantages of tourniquet use, including whether not using a tourniquet reduces pain, facilitates mobilisation and recovery, and shortens length of stay.
2. To study whether use of a tourniquet affects leg muscles during and after surgery, as measured by with use of microdialysis to quantify level of ischemia .
3. To determine whether prosthesis fixation, measured by RSA, is affected by tourniquet use. Because third generation cements secure prosthesis fixation, the investigators do not expect to find any clinically significant migration (less than 2 mm) 2 years after surgery.

Perspectives:

The investigators hope that the results of our study will improve rehabilitation regimes so that patients will experience less pain after surgery and thus achieve more rapid mobilisation and return to their daily lives.