Mini-incision surgery: Patients want it, but is it safe?

MIS debate covers safety, recovery rates, complications, cosmesis and whether patient expectations are an outcome determinant.

Issue: Issue 2 2006

ORLANDO, U.S.A. – As with all new orthopaedic techniques, mini-incision surgery is in the midst of an evolution. Some orthopaedic surgeons believe now is the time for the mini-incision, because some studies have proven its safety, recovery rates are better and patients are more confident in their outcomes.

Robert L. Barrack, MD [photo]
Robert L. Barrack

Not so fast, said Robert L. Barrack, MD, of Washington University School of Medicine in St. Louis, who, although he performs minimally invasive surgery (MIS) on select patients, is concerned about an increase in complications with the widespread use of MIS total hip replacement (THR).

“An increase in the incidence or severity of complications is unacceptable, given the success rate of standard total hip replacement and the lack of documented benefit of MIS,” he said at the 22nd Annual Current Concepts in Joint Replacement Winter 2005 Meeting.

MIS – the time is now

Other studies still find MIS procedures safe, said Lawrence D. Dorr, MD, of the Arthritis Institute at Centinela Hospital in Inglewood, U.S.A. “[These procedures] are different than just a shortened long incision; they are better, and they are certainly desired by the majority of patients.”


This large patient underwent primary total hip arthroplasty with a small incision and experienced early dislocation.

Specifically, the posterior mini-incision is the most successful and easiest type of MIS, Dorr said. “Pain and function are improved in the recovery period, and perhaps most importantly, mentally this incision is better for the patients.”

Dorr and his colleagues conducted a randomized study challenging patients to avoid intravenous narcotics and to be sent home within 48 hours with a single walking-assistive device. They found that standard-incision patients used statistically more intravenous narcotics. Although both the standard-incision and MIS patients achieved good pain scores, scores were better in the MIS patients for the first 48 hours.

“Twice as many patients made it home in 48 hours with the small incision, compared to the [standard] incision,” Dorr said. “Likewise, more patients with a small incision made it home on a cane or a single crutch with 90% of those, compared to 60% with the [standard] incision.”

The researchers also objectively measured gait analysis for a posterior MIS incision, an anterior small incision operation with no muscle cut and a standard posterior operation. At three months, they found that leg strength for the standard incision was worse than both small incisions. Stride length and walking speed were better in the posterior MIS incision patients.

Despite these results, some studies find no difference in short-term clinical advantage or outcome between the standard incision and MIS, Barrack said, and complications are more frequent and more severe with MIS.

One example: A Stanford University study by Woolson et al in 2004 found complications, including acetabular malposition, stem undersizing and wound problems, in MIS performed by fellowship-trained surgeons.

Barrack presented a list of complications that occurred within the past couple of years. “Many were done by experienced surgeons, the diagnosis was often delayed, all required reoperation, always by another surgeon, and the result was often compromised,” he said.

He presented a series of a dozen cases, half of which were referred to him and half were treated by colleagues, of straightforward primary total hips that required revision within the first year for complications of MIS THR.

In one case, a surgeon attempted primary hip surgery using a 9-cm incision in a short, slightly heavy patient. After reaming away the superior and posterior rim, the surgeon aborted the procedure and performed a complex revision with metal augments days later. The patient died from a postop embolic event.

X-ray

A CT scan on this same patient revealed that the anterior column and superior rim had been reamed away (left) and there was a malpositioned cup and stem (right). As a result, Barrack performed a complex early revision.

Courtesy of Robert L. Barrack

Importance of incision length

Patients may not be as concerned about incision appearance and length as once thought.

“The logical but unproven assumption is that patients like shorter incisions, but what about the overall appearance of the incision? How important is incision length to most patients?” Barrack said.

In a Stanford University study from Mow et al in 2005, two plastic surgeons rated total hip scars in a blinded manner, rating more MIS scores as poor and more standard incisions as good, Barrack said. They also found more wound problems in the MIS group. Other studies differ.

Looking at the psychological implications, Dorr and his colleagues evaluated 210 consecutive patients; 66 had a standard incision. “The results show that at six weeks, patients with an MIS incision exceeded their expectations, and patients with a [standard] incision wished even more that they had received a small incision,” Dorr said.

Pain was good in both groups, and only 50% of patients judged cosmesis as a factor – fewer patients than at preop. But, although all patients met their goals and there were no complications, only 10% would have a standard incision and 70% who had a standard incision wanted a small incision. “These patients feel that there’s more confidence with a small incision; that provides a more positive attitude toward their outcome,” Dorr said.

Preop expectations

Barrack believes that outcome is related to the patient’s preoperative expectations. A randomized study by Wright et al in 2005 found patient expectations more of recovery determinant than incision length.

The researchers separated 50 patients blinded to incision length into three groups. Group one underwent mini-incision THR, group two had standard-incision THR and group three insisted on mini-incision THR. “Groups one and two were equivalent in every way at every time interval,” Barrack said. “Group three … ambulated greater distances earlier, used fewer pain meds early.”

MIS may be appropriate for selected surgeons at selected centers, with the proper training, experience and resources, Barrack said. He performs MIS “in the handful of patients that are convinced that they need to return to work and that they need a small incision. In my practice, that’s 10% to 20% of patients at most.”

For more information:
Barrack R. The mini-incision: occasionally desirable, rarely necessary - Affirms. #2.
Dorr L. The mini-incision: occasionally desirable, rarely necessary - opposes. #3. Both presented at the 22nd Annual Current Concepts in Joint Replacement Winter 2005 Meeting. Dec. 14-17, 2005. Orlando, U.S.A.
Woolson ST, Mow CS, Syquia JF, et al. Comparison of primary total hip replacements performed with a standard incision or a mini-incision. J Bone Joint Surg Am. 86-A(7):1353-1358, 2004.
Mow CS, Woolson ST, Ngarmukos SG. Comparison of scars from total hip replacements done with a standard or mini-incision. Clin Orthop Rel Res. 441:80-85, 2005.
Wright JM, Rosse D, Rosse S. A prospective, randomized patient-blinded comparison of mini vs. standard-incision THA. Presented at the American Academy of Orthopaedic Surgeons 72nd Annual Meeting. Feb. 23-27, 2005. Washington.