The mini-posterior total hip replacement (THR) is done through a six- to nine centimeter long incision. That's about two inches. Posterior means it is done from the backside. In other words, the large buttocks muscle (gluteus maximus) is split to reach the hip.
The hip capsule and external rotator muscles close to the hip are cut open and then repaired later. Patients like this method because the incision is behind and can't be seen without a mirror. Some say they got better faster with this approach.
The two-incision operation is done with two incisions from the front of the hip. Both incisions leave scars that can be seen when bathing or changing clothes. Patients often feel annoyed by seeing these scars, but the scars don't impair function or keep anyone from doing their daily activities.
A recent study compared these two methods on patients who had both hips replaced. One hip was done with the mini-posterior method. The other hip was replaced using the two-incision approach. There wasn't any difference in how fast patients recovered from these two operations. About two-thirds preferred the mini-posterior approach because they couldn't see the scar.
The two-incision THR is more technically demanding for the surgeon. Since there may be no advantage to this method, the mini-posterior may become the preferred method by patients and surgeons.