The use of bloodless field is a helpful and important method in orthopedic surgery. The
surgery can be done without interrupting bleedings, while keeping an exact overlook of the
anatomy. However the method is not without risks, and complications of various kind may
occur. One of the most important factors to minimise the risk of complications, is to keep
the lowest possible cuff pressure. Previous electromyography (EMG) studies have indicated
neuromuscular abnormalities after bloodless field among many patients which may lead to a
prolonged rehabilitation period since they cause a postoperative weakness in the muscles.
Although in these studies an unnecessary high tourniquet pressures were used and the EMG
tests were made 6 weeks and 6 months after the surgery.
With today's demand for fast rehabilitation, there is a need for better knowledge if lower
tourniquet pressure in bloodless field surgery may lead to less neuromuscular abnormalities.
Limb Occlusion Pressure (LOP) is the tourniquet cuff pressure required to occlude the blood
flow. It accounts for a patients limb and vessel characteristics and the type and fit of the
tourniquet cuff. The method has developed and is now simplified, by using an automatic
(plethysmographic) sensor placed on the second toe on the involved limb, and after
administration of anaesthesia, and immediately before limb preparation and draping it
measures the limb occlusion pressure.
When surgery starts, the cuff is inflated again; plus a safety margin based on the LOP
pressure measured. The LOP method is still rarely used it has been seen as difficult and time
The primary aim of this study is to investigate whether you can reduce the used tourniquet
pressure with the new LOP measurement technique and still have a adequate bloodless field;
and if this will lead to any clinical difference regarding postoperative pain. The secondary
aim is to investigate the difference between the test groups concerning muscle function and
wound healing and if these are remaining and of clinical importance. The third aim is to
study how common neuromuscular abnormalities are after the use of bloodless field with lower
cuff pressures and if there are any differences between the standard method and the LOP