Minimally Invasive Total Hip Replacement

Minimally invasive total hip replacement is a surgical technique used to perform a total hip replacement using smaller incisions as compared to the traditional approach. The minimally invasive technique also utilizes less cutting of the tissues besides a smaller skin incision.

The technique is fairly recent as compared to the traditional hip replacement technique. While minimally invasive hip replacement offers a lot of benefits compared to the traditional approach, the technique may not be best suited for all patients.

X-ray showing a lateral view of a total hip replacement.

Hip replacement surgery is most often performed for the management of end-stage arthritis of the hip joint. The surgery involves the removal of the diseased ends of the bones that form the hip joint. Prosthetic metal and plastic parts are then capped over the bony ends to recreate the function of the natural joint.

Minimally invasive surgery

The prosthetic implants used in a minimally invasive hip replacement surgery are the same as the ones used in a traditional approach. The instruments used in the minimally invasive technique are however different from the ones used in the traditional approach.

Special instruments may be utilized to help the surgeon perform the surgery through a smaller incision. The special instruments are useful while preparing the bony socket and the femoral canal for the implants.

Generally, minimally invasive surgery is only advised in patients who require a primary uncemented hip replacement, are physiologically younger, have a thin physique with relatively normal hip anatomy.

Minimally invasive surgery is not recommended in patients undergoing revision surgery or complex primary hip replacement surgery. Patients that require revision hip replacement or complex primary hip replacement need a significantly larger exposure of the hip joint to perform the surgery.

The technique is also not advised in patients who may have undergone any kind of prior hip/thigh surgery such as osteotomy, fracture fixation with screws/nails/plates, etc. Obese, highly muscular, and patients with multiple medical co-morbidities are also not good candidates for minimally invasive surgery.

Patients with a bone tumor, metabolic bone disease such as osteoporosis, inflammatory arthritis such as rheumatoid arthritis who may need a hip replacement are also not good for a minimally invasive technique. Similarly, patients with severe hip deformities such as contractures or bony fusion of the hip may require an extensive approach used in traditional surgery.

Technique differences

During a traditional hip replacement surgery, the surgeon gives an incision that may be approximately 10-12 inches long. The incision in the common posterior approach is given at the back of the hip joint. The incision in anterior hip replacement is given in the groin area and given at the side of the hip joint in the direct lateral approach.

The neck of the femur is cut to free the head which is subsequently extracted out. The acetabulum socket is then prepared through serial reaming which is usually followed by the preparation of the femoral canal.

An acetabular shell is usually press-fitted in the bony socket or may be fixed with bone cement. A femoral prosthetic stem is press-fitted in the femoral canal and is capped with a prosthetic head of the femur. The prosthetic head is then relocated in the prosthetic cup.

In the case of minimally invasive surgery, the skin incision is usually half the size of the incision used in the traditional approach. The surgeon may utilize minimally invasive techniques through either of the approaches used in the traditional hip replacement.

Surgeons may also use a double incision, with an incision in front of the hip and the back. The incision in the groin is used for the preparation of the bony acetabulum and prosthetic cup placement. Similarly, the incision in the back is used for femoral canal preparation and the placement of the femoral component.

Advantages

The smaller skin incision used in minimally invasive surgery leads to a smaller surgical scar. During minimally invasive technique fewer tissues are cut/separated which leads to less intraoperative blood loss. Additionally, the patients may have a shortened postoperative recovery. The technique preserves the abductor muscles at the side of the hip joint that is important for normal walking.

Intraoperative image showing the removed head of the femur and the neck of the femur.

Limitations

The exposure to the joint is greatly reduced in a minimally invasive technique. The limited exposure may potentially lead to mal-aligned implants. Proper positioning of the implants is necessary to prevent prosthetic hip dislocation and ensure a stable range of motion.

The minimally invasive technique utilizes special instruments to perform the surgery through a narrow field. The instruments may put stress on the tissues and the skin that may be double the stresses in the traditional approach. The additional stress on the skin and the tissue may lead to problems of wound healing and tissue damage.

The narrow field of surgery in a minimally invasive technique may increase the chances of damage to the lateral femoral cutaneous nerve, femoral nerve, or the sciatic nerve depending upon the approach used in surgery. The technique may also increase the chances of an intraoperative prosthetic joint fracture.

Conclusion

Hip replacement surgery is one of the most successful surgeries in the history of medicine. The traditional approach has been proved to be highly effective in numerous long-term studies. The minimally invasive technique requires a significant amount of training by the surgeon to master the technique.

The minimally invasive technique offers advantages over the traditional approach; there is not enough data to conclusively state that it is more beneficial than the traditional approach. Speak with your operating surgeon regarding the type of surgery that may be best suited in your case.