FAQ

Q: Mini-incision surgery is a specialised technique performed by only a few talented surgeons. Is this the case for MIS in hip replacement?

A: Even more so. Using a modified MIS posterior approach, training surgeons is quite easy if the surgeon is already carrying out more than 50 THA per year using the conventional posterior approach. Surgeons using anterior or antero-lateral approaches would require a more lengthy training process due to the change in approach.

Q: Mini-incision surgery has been around for a while, what makes MIS so important?

A: Mini-incision usually implies an incision around 10-15cm and is usually a smaller incision than the conventional approach and should not be confused with minimally invasive surgery. The MIS incision may well be the 10cm part of the conventional incision but special instruments have to be used to allow the surgery to be carried out. However, MIS is often carried out using a new surgical approach, i.e. two incision surgery or a modified posterior approach. If the surgery is carried out with ideal MIS instrumentation, MIS is less tissue disruptive than mini-incision surgery.

Q: Conventional hip arthroplasty with Metal on Metal articulation is gaining popularity as an option for primary hip replacement rather than being used to revise failed resurfacing arthoplasty. Have you developed bespoke instrumentation for MoM hip arthoplasty to be delivered through a minimally invasive surgical approach?

A: For minimally invasive hip replacement it is imperative that circumferential exposure of the acetabulum is achieved. This has particular relevance with MoM big femoral head and uncemented acetabular components. If circumferential visualisation of the acetabulum is not possible soft tissue interposition from the periphery of the acetabulum will occur and compromise fixation of the acetabular component. The Comis MIS retractor system allows direct circumferential visualisation with very soft retraction.

Other MIS retractor systems have been developed with extra long handles. These are designed to keep the assistant’s hands out of the surgeon’s way, and also away from the field of exposure. However, by the sheer fact that they are long handles, they impart greater forces on the soft tissues and cause more soft tissue damage. The Comis MIS retractor system uses minimal force and is low profile so that it does not interfere with the field of view. The other important aspect is to have perfect reaming of the acetabulum to allow for the anteversion of the acetabulum and also to have a closed position of the acetabulum in the AP plane. This can be achieved using the Chana ™ reamer handle which is universally available through Precimed.

A curved acetabular impactor which will allow delivery of the acetabular component into its anatomical anteverted and close position. It should be kept in mind that with the MoM articulation the acetabulum is positioned in a much more closed position, i.e. near 40° to give better wear of the articulation.