Minimal Invasive Hip Surgery, How we do it.

Aalsters Stedelijk Ziekenhuis, Alost, Belgium

Minimal invasive hip arthroplasty gained attention in the media since 2000 and was promoted by several medical companies. There is discussion about the definition of minimal invasive hip arthroplasty. Some surgeons consider a skin incision of less than 10 centimetres as minimal invasive, others define minimal invasive as a technique that has respect for the normal anatomy and is performed with minimal soft tissue damage.

In our centre, when we started performing THA in 1978, we used transgluteal approach. While gaining more experience we progressively shortened our incision without any change in instruments. The last years, the skin incision in normal patients was never more than 10 to 12 centimetres. When special designed retractors and reamers were used it was possible to shorten the incision even more. But besides decreasing the length of the incision, no changes were made in the technique it self. Damage to tendons en muscles was the same as when we started. We named this procedure a MIS 1.

Three years ago we started with the two incision technique (MIS 2) as introduced by Dr. Berger. The acetabulum was prepared and the cup was inserted through a small anterior incision. The femoral shaft was prepared through a small lateral incision which in size and location is comparable to an incision made for insertion of an intramedullar nail. In the beginning the femoral stem was placed under fluoroscopic control resulting in very high radiation exposure. Therefore we've changed the position of the lateral incision. The new incision was made over the greater trochanter with direct view on the osteotomised femoral neck thus insertion of the femoral component was possible without fluoroscopy. We performed 150 THA using the MIS 2 approach. Benefits according to Berger were also seen in our group: less limping, faster rehabilitation, less blood loss. The only complications we had in this group were two cases of transient meralgia paresthetica and one case of superficial wound infection.

In August 2004 we visited the Medical University of Innsbruck where the direct anterior approach (MIS 3) was introduced to us. In fact the incision used in MIS 3 is the same as the one we use for our anterior MIS 2 incision but more proximal and lateral and slightly more oblique. Both acetabular and femoral components are introduced through the same, anterior, incision. The main advantages of the MIS 3 approach are due to its great respect to the anatomy around the hip, no muscles are damaged. Until December 2004 we performed 50 THA using the MIS 3 approach. In our group the direct post operative results were very promising with patients already walking the day of the operation and some of them leaving the hospital at the third post operative day. Compared to classic THA operation we saw a decreased blood loss, less post operative pain and a faster rehabilitation. In this group we only saw one superficial wound infection which needed revision of the wound. Of course follow up is too short to make any predictions on long term results.

As for every new procedure and also for MIS 3 there is a learning curve, especially while the new, anterior, site of incision is hardly known by orthopaedic surgeons and due to the proximity of neurovascular structures. It is important to be familiar with the MIS 2 technique before starting a MIS 3 procedure. First to become familiar with the anterior incision and secondly in case of impossibility to place the femoral stem through the anterior incision you may need a lateral incision as escape. Fortunately we only experienced this once in our second case

To conclude we believe that the low blood loss and low complication rate are at least in part due to the minimal invasive nature of this approach , which keeps soft-tissue trauma to a minimum and leads to faster postoperative mobilisation and rehabilitation. Further explanation of the technique and the results of MIS 3 will be given in our presentation.


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