Is The Evidence For or Against Mini-Incision for Hip Replacement?

Can you guess how many people have a total hip replacement in the United States every year? Would you be surprised to know that at least one-quarter of a million total hip replacements are done annually? And it is expected that over the next few years, that figure will more than double.

With so many people in the Baby Boomer generation now getting a hip replacement, it’s natural that they seek out this surgery. More and more hip replacements are being performed with a mini-incision (less than 10 centimeters or two and a half inches long). Surgeons need to know what evidence there is to favor this approach when advising patients which way to go (mini-incision versus traditional open surgery).

To help with these management decisions, a group of researchers from the Health Services Research Unit at the University of Aberdeen in Scotland conducted a very thorough electronic literature search. They searched on-line for any and all studies comparing the results of a mini-incision approach to hip replacement to the results using a standard incision.

They found 15 studies that met the eligibility requirements for good quality studies with a total of 1857 patients (when all combined together). The studies were not all equal in quality or design. For example, the number of subjects ranged anywhere from 20 to 219. In some studies, the surgeon had a great deal of experience performing the minimally invasive procedure. Other studies noted that the cases involved were with surgeons just getting started with this approach and technique.

Follow-up varied from six weeks to three years. But outcomes could be compared by looking at amount of blood lost, length of operative time, number of days in the hospital, and complication rate. Complications included dislocations after surgery, level of pain, excessive blood loss, nerve injury, infection, fractures, blood clots, and the need for a second (revision) surgery.

Analysis of all the data showed that there were small differences in early results but in the end, no major differences in outcomes between the two groups. Sure, there was a bit less blood lost during the mini-incision procedures and the hospital stay was a day or two shorter. But there were no significant differences between the two groups when looking at complications or revision rates.

The authors point out the fact that the available studies were all fairly short-term. So long-term results cannot be compared at this time. Without the benefit of 10 to 20 year studies, it’s not clear if the mini-incision approach provides any major advantages over the traditional standard-incision surgery.

With more direct marketing to consumers, a greater number of American adults are seeking what is now referred to as “the operation of the century” — total hip replacement. Surgeons must be prepared to guide patients through the decision-making process based on clear evidence, not advertising hype. And before that can be possible, more high-quality, well-designed studies are needed.

At this point all that can be said for sure is there aren’t any major differences in short-term results between standard and mini-incision for total hip replacement. The authors of the study summarize it well in a single statement: Current evidence is not strong enough to support one surgical technique over the other.