In the absence of evidence--why bother? A literature review of minimally invasive total hip replacement surgery.

Two new total hip replacement (THR) procedures have been termed minimally invasive. It is claimed that these smaller incision techniques reduce soft-tissue trauma, decrease postoperative pain and blood loss, speed recovery, and reduce the length of the hospital stay compared with hip replacement using the standard incision technique. These new procedures use either one small 6- to 10-cm incision through a posterior, lateral, or anterior approach or two very small (a 2.5 cm posterior incision for placement of the femoral component and a 5-cm anterior incision for placement of the acetabular component) incisions to accomplish the same THR procedure that requires a standard length incision of 15 to 20 cm. Controversy exists on whether these small incision THRs are actually minimally invasive. It is debated whether a small skin incision that requires the application of high forces on the soft tissues for exposure of the joint but less muscle dissection will produce less overall trauma to the patient than a larger incision with wider muscle dissection but with lower retraction forces. If small incision THR techniques are less traumatic overall, then they should produce less pain, lower transfusion requirements, a shorter hospital stay, and a faster recovery for patients. The other important issues regarding small incision procedures are whether the decreased visualization provided by these techniques is adequate to prevent a higher complication rate from damage to the surrounding neurovascular structures and outcomes that are equivalent to those found for THR using the standard technique. A review of the literature to date provides no convincing evidence of any significant advantages of small incision THR compared with standard incision THR other than a shorter surgical scar. Comparison studies that prove both significant advantages and low complication rates for small incision THR are needed before these procedures can be recommended for general use.