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Data suggest that technique should be used with caution
Researchers at the Mayo Clinic said their experience with the procedure was not optimal.
Advocates of minimally invasive and two-incision hip replacements claim that they provide the advantages of less soft tissue trauma near the hip joint, a potentially quicker recovery, less pain and a better functional result.
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However, I think all of us probably recognize that none of these proposed advantages have been proven or supported by well-done, published peer review studies.
At the Mayo Clinic, we became interested in this operation in late 2003, early 2004. We collected results from five studies that we performed at our center in an effort to look at this operation a little more closely.
The first trial was a cadaveric study looking at two-incision vs. mini-posterior-incision approaches. We took 10 cadavers in matched pairs that were free of any hip deformity. The right and left sides were randomly assigned to undergo a two-incision or a mini-posterior procedure on the contralateral side. I performed the mini-posterior exposures and Mark Pagnano, MD, my partner, did the two-incision side. He had already treated 80 patients with this approach, so he had a lot of experience.
Through this investigation, we concluded that the two-incision surgery did substantially more damage to the gluteus medius and gluteus minimus muscles vs. a mini-posterior exposure. There was similar damage to the tendons of the gluteus medius in the two-incision and mini-posterior groups. There was a lot more variability in the two-incision group as far as muscle damage goes.
More investigation
The second trial was a retrospective study that Pagnano performed. He evaluated his first 80 total hip replacements using the two-incision technique, as described by Dana Mears, MD, and Richard Berger, MD. All had uncemented cups and uncemented stems, and the mean operative time was just under 70 minutes.
He found a 14% early complication rate in this series, which was alarming. Significant complications included four intraoperative fractures, three postoperative fractures, one dislocation, one loose femoral stem and one infection. Other surgeons at other centers have reported a similar, humbling experience.
The third investigation involved our patient survey. We asked a unique group of 26 patients who had staged, bilateral hip replacements performed with a two-incision approach on one side and a mini-posterior on the other, “Do you prefer a two-incision hip replacement or a mini-posterior total hip replacement?�
Pagnano performed all of the surgeries. All patients had the same anesthetic protocol, the same rehab protocol, and there were no complications. Clinically, all of them are doing well with their hips. We administered the survey 6 months after the second hip replacement.
We found that two-thirds of the patients preferred their mini-posterior total hip replacement, one-third preferred the two-incision hip, and two patients stated they had no preference of either side. We concluded that the majority of patients who have a successful two-incision total hip replacement on one side and a good mini-posterior total hip surgery on the other prefer the mini-posterior side, based on a retrospective survey.
Measuring strength and gait
The fourth investigation was a randomized, prospective trial on strength and gait, comparing patients who received either the two-incision or the mini-posterior procedure. We took a subset of 24 patients who were between 40 years old and 85 years old and randomized them by computer to receive either a two-incision or a mini-posterior approach.
The demographics of the groups were the same; they received the same implants, anesthesia and postop protocol. We looked at gait analysis, strength testing at preop, and at 6 weeks after the surgery. The conclusion of that study: There was no significant difference in strength and gait among patients at 6 weeks after receiving a two-incision or mini-posterior replacement.
Finally, we are in the process of reviewing the results of a prospective, randomized trial comparing the two-incision vs. the mini-posterior approaches. Seventy-two patients were randomized via the computer to undergo either the two-incision or mini-posterior approach (36 patients in each group). All patients had similar demographics and received the same components, the same anesthesia and postop therapy protocol.
At 1 year, we concluded that patients who underwent the mini-posterior approach recovered faster than their colleagues with the two-incision surgery, as measured by the time they ambulated without a walker and the time they returned to their daily activities. There were no differences in other outcome parameters, the SF-12 or Harris Hip Score between the groups. There were no significant differences in complications, and the operative time was a little longer for the two-incision technique.
Some surgeons have stated they can do the two-incision approach without marked complications in selective series, and I think the group from Rush University in Chicago should be credited for changing our attitude about recovery after hip surgery.
However, we feel the two-incision method does have the potential to produce marked muscle damage and high-complication rates. Patients don’t prefer it, there is no strength or gait advantage gained by receiving it, and in a prospective, randomized trial, we saw no clear advantage in receiving the two-incision approach over the mini-posterior.
In light of the available data and unpredictable results, I questioned whether the routine orthopedic surgeon should abandon the two-incision approach. But after a fairly close look at the Mayo Clinic, we have abandoned the two-incision technique as described and popularized by Mears and Berger.
For more information
- Trousdale RT. Two-incision THR: A failed experiment — Affirms. Presented at the 23rd Annual Current Concepts in Joint Replacement Winter 2006. Dec. 13-16, 2006. Orlando, Fla.
- Robert T. Trousdale, MD, professor of orthopedics, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905; 507-284-3663; Trousdale.Robert@mayo.edu.