Patients and surgeons alike are interested in a painless and speedy recovery after a total hip replacement (THR). Can it be done? Well, it hasn’t been accomplished yet, but efforts are being made to move in that direction. The use of minimally invasive (MI) procedures may be an important development toward achieving this goal.
The authors of this article are surgeons from The Johns Hopkins University in Baltimore, Maryland. They took the time to look through all the most recent studies on minimally invasive total hip surgeries. They wanted to know which surgical approach works best? What really makes a difference in outcomes? Does it depend on the surgeon’s technique? The patient’s expectations?
Here’s what they found. First, minimally invasive surgery refers to any operation where the surgeon changes how long or how deep the cut is made into the tissue. The hope is that with less trauma to the soft tissues (especially the muscles around the hip), the patient will be able to recover that much faster.
But there is much debate about the exact incision length to qualify as minimally invasive. Is it five inches or less? Three inches? One inch? Is there a difference between minimally invasive and what would be considered a mini-incision? Does it even matter? The authors think so. They say that a truly less invasive approach isn’t just a shorter incision. Minimally invasive means no incision into the muscles. No tendons are cut. And if the joint capsule is disrupted, it is easily repaired.
Do the patients recover faster with one type over another? And there are two different basic approaches used with minimally invasive total hip replacements: the mini-posterior and the two-incision approach. Are the results better with one approach over another?
You can see how comparing all these different types of minimally invasive surgeries adds to the difficulty of sorting out which one works best. There aren’t enough studies out there yet to really make comparisons of all the types, approaches, depths, and so on.
The authors say that right now the studies published on minimally invasive techniques can be broken down into three categories: the mini-posterior approach, the anterolateral approach, and two-incision approaches. They summarized what they found for all three.
There are many advantages to the mini-posterior approach. The group of muscles usually cut to remove the old hip joint aren’t touched. The gluteus maximus (buttock) muscle is split to get to the hip joint, but the length of the split is much shorter. The incision into the joint capsule is also smaller and repaired without any negative effects.
But for all these positives, when surgeons compared the results between a standard posterior total hip replacement and the mini-posterior approach, guess what? No difference between the groups during the postoperative period. Pain levels and walking ability were the same.
There were more studies on the anterolateral approach but not all were of high enough quality to make their results very note worthy. There was less blood loss reported and shorter time in the operating room for the minimally invasive approach compared to the standard anterolateral procedure. Functional outcomes (walking speed, muscle strength) between the two groups were better for the minimally invasive patients. But this was only true for the first year postoperatively. After that, things evened out between the two groups.
Studies comparing the two-incision and mini-posterior approaches are limited and with a small number of patients. In one study, the two-incision operation was reported as more complex and taking longer than the mini-posterior approach. Another study comparing the same two approaches agreed that the mini-posterior approach was faster with less blood loss but reported that the patients recovered faster when the two-incision method was used.
Finding studies that truly compare two different surgical approaches with all else being the same just doesn’t happen. Different types of implants are used. Surgeons have different levels of expertise and experience. The amount of muscle sparing that takes place varies considerably. The type of rehab program after the surgery isn’t the same from place to place.
What might be more important than the type of incision made is the way patients are treated after surgery. Several studies have shown that patients who are on the fast-track after surgery get better faster.
The fast-track means they get a patient-controlled pump to manage their pain. They start rehab sooner, and the therapist provides a more aggressive program. In all cases, patients in the fast-track groups were discharged sooner, could walk better, and were more satisfied than patients following the standard rehab protocol. This was true no matter what type of incision or approach was used to do the surgery.
There’s one other thing to consider about minimally invasive procedures. Even if the minimally-invasive approach doesn’t yield better functional outcomes, patients like how it looks. A shorter incision just looks better, and patients are asking for that. Patients also want an implant that will last as long as possible. And that factor is more important to them than the length of the scar or how long they are in the hospital.
The authors conclude that there are many, many variables to study and compare when trying to decide which approach is the best one for total hip replacements. We’ve only begun to scratch the surface when comparing things like preoperative counseling, analgesia, and rehabilitation programs. While the surgical approach might make a difference, there’s at least enough preliminary information to suggest that the postoperative treatment process may be equally (if not more) important.