MIS or minimally invasive surgery is a recent development in the field of hip replacement surgery. It all started about 4 years ago when a couple of surgeons in the US devised a new method of "opening" the natural hip joint through a smaller cut on the skin and with less muscle trauma. The soft tissue damage caused in exposing the natural hip and implanting an artificial replacement was less than in the conventional operation. They found that patients appeared to have less pain after this surgery and were also able to recover the use of the operated leg quicker and therefore left hospital sooner when compared with patients who had undergone a conventional hip replacement..
A lot of development work went into this method of implanting artificial hips. The smaller incision had the disadvantage of making it difficult for the surgeon to visualise the tissues. Special instruments had to be developed to minimise this difficulty. Light conducting fibreoptic cables were used within the incision area to aid visualisation as the light from the overhead lights was sometimes insufficient. The surgeons were able to reduce the length of the incision from the conventional 15 - 25 cm to about 10 cm. With time it became apparent that the length of the skin incision per se was not the main advantage with this technique. Instead it was the reduced trauma or damage to the muscles around the hip that was the key to early functional recovery and the reduced pain with these techniques.
There are very few surgeons who have done large numbers of operations using these techniques. It is apparent from their experience that
a). These operations are technically more demanding.
b). There is a learning curve with these operations; i.e., surgeons get better
at the operation as they do more.
c). There is a higher complication rate. The main complication, in addition
to the usual ones, appears to be a fracture of the femur bone either during
or shortly after surgery. There are also reports of significant numbers of patients
reporting numbness on the front of the thigh with some of these techniques.
However, the numbness appears to be temporary in the majority and settles spontaneously
with time.
d). Not all patients are suitable for these techniques. At times it may become
necessary to convert a MIS approach to a conventional one during the operation.
e). It is possible for patients to go home in 24-48 hours after the two incision
or single anterior incision approach.
f). There is no scientific evidence at this time of a specific advantage in
the long term with the MIS hip over that carried out in the conventional manner.
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