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Limited use of computer-assisted surgery begs the question: Quo vadis navigation?

Issue: Issue 4 2012

ByRené Verdonk, MD, PhD

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When I first encountered orthopaedic navigation in the last century, it was new technology. Early reports on its potential impact proclaimed that long-term results should provide better outcomes, and although further studies of navigation are required, it offers the ability to improve mean axial alignment and remove outliers from the Gaussian curve.

But what has navigation achieved and where is it headed?

Navigation was initially introduced in spine surgery. When experience alone could not improve spine surgeons’ consistent and accurate screw placement for corrective stabilizing spondylodesis, computer navigation helped them avoid serious problems affecting the nerve root or spinal canal if the screw placement was done incorrectly. It appeared the way to go for less experienced surgeons and proved helpful for more experienced surgeons in special cases.

 

Reneé Verdonk

Despite there being more spine surgeons than ever worldwide, navigation for spine applications now has decreased to the point where it is typically only indicated in select cases. This has once again led to having few surgeons skilled with navigation techniques.

Improve alignment

Computer navigation was next introduced for joint reconstruction, mostly to improve axial limb alignment and implant positioning in total knee arthroplasty (TKA), both of which can affect short-term outcomes. Suddenly orthopaedic surgeons who occasionally performed TKA were confronted with a computerized option for obtaining correct TKA implant positioning. They were pressured to use the new technology to improve outcomes.

However, surgical navigation was also associated with increased hospital expenses. Many costs were not covered. Ultimately, orthopaedic navigation evolved into a technique with limited use in the implantation of orthopaedic devices.

To understand how navigation was used in typical practices and what its future utilization and applications may be, I and my colleagues sent 2,800 questionnaires to members of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA). We had a 12% return rate and published the results in 2008. Most respondents (87%) were in practice at least 6 years, with the majority of them in practice 6 years to 20 years, which showed that new and experienced clinicians had opportunities to use navigation. Annually, 10% of respondents performed fewer than 10 TKAs and 20% performed more than 100 TKAs.

Surprisingly, an equal number of respondents were from academic institutions and private/public hospitals. About 50% of departments surveyed owned a navigation system and physicians with access to a system had 20 years or more experience. About 62% of academic institutions had navigation systems, with fewer systems at private-public hospitals. Orthopaedic surgeons who performed more than 50 TKAs per year had increased access to navigation systems (60%); 11% of respondents never used navigation despite having a system available.

When we conducted the survey, 83% of navigation cases were performed image-free, 60% of navigation cases were for primary TKA, and 23% of navigation was used to place unicompartmental knee arthroplasty components. Minimally invasive surgery was popular at the time and surgeons applied navigation in these cases with variable success.

Half the users operated with navigation to avoid major intraoperative deviations in alignment and it is remarkable to find that higher volume departments used navigation in all their cases.

Although the amount of time to complete an orthopaedic case using computer navigation has decreased recently, navigation remains time-consuming. It was unclear from survey results whether the limited use of navigation by some surgeons was due to the time factor. Users and nonusers alike found navigation beneficial as an educational and teaching tool and for obtaining better TKA alignment. However, many of the nonusers surveyed found the system awkward and time-consuming. Users and nonusers both saw navigation playing an increased role in orthopaedic surgery in the future despite having their doubts about its long-term clinical value.

It is interesting that with its many reported advantages about half of all navigation equipment is used in fewer than 25% of cases.

Second survey, similar results

In 2009, members of the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine completed a similar questionnaire. Overall results were similar in that respondents who used navigation in more than half their cases did so for the purposes of greater surgical precision and teaching.

If the variability in utilization shown in these surveys and the recent scientific literature are any indication, orthopaedic navigation has lost its hype despite retaining a limited place in the armamentarium for high-volume surgeons. The indications for navigation have recently been extended to soft-tissue (ligament) surgery — which requires surgical precision — and revision TKA, although its use in revisions is still limited.

The general consensus is that navigation can help reduce the number of TKA alignment outliers, yet there is no scientific proof that when outliers are eliminated, the clinical outcomes are any better. TKA requires a meticulous approach coupled with a precise surgical technique. The best long-term clinical outcomes will always be associated with the surgeon who has the most expertise with the procedure. Perhaps navigation may bring added value in these cases, but not on its own.