COPENHAGEN, Denmark — Despite Austrian and Swiss
investigators finding some similar mean postoperative deviation angles and no
differences in range of motion, ligament balancing and anterior knee
characteristics among patients randomized to undergo total knee arthroplasty
via
conventional or
computer navigated techniques, they concluded the navigated
procedures were more accurate based on 5-year results with the procedures.
Mark Widemschek, MD, of the Department of Orthopaedic
Surgery, Academic Teaching Hospital, Medical University of Innsbruck in
Feldkirch, Austria, presented the study at the
12th EFORT Congress 2011.
“There is a survival rate after 5 years of 98% in
the navigation group and 95% in the conventional group,” he said, noting
200 patients were equally randomized into two groups and their outcomes were
assessed via long-leg radiographs and the WOMAC, Insall Knee and Hospital for
Special Surgery (HSS) Knee scores.
Based on the radiographic measurements, Widemschek and
colleagues found better frontal plane axis results in the navigated group of
1.67° ± 1.6° compared with 2.44° ± 2.2° in the
conventional total knee arthroplasty (TKA) group. The team also identified
fewer patients in the navigated group with valgus/varus deformity of the
mechanical axis of the limb that fell outside 3° range.
“The Insall Knee Scores showed a significantly
better result for the navigation group,” Widemschek said, noting those
total scores were 191 points vs. 181 points in the conventional group.
However, the results showed the HSS total knee score was
only slightly better in the computer-assisted group and both groups’
results were similar based on the WOMAC total score.
Investigators used the same two designs of prostheses in
both arms of the study, according to Widemschek.
“The clear limitation of our study was that we were
not allowed to perform a postoperative CT — we cannot get the information
about the rotational positions of the component — and also that there was
a loss of follow-up for 15% to 20% of the patients.”
Orthopedists at Widemschek’s center currently
restrict their use of TKA navigation to such special indications as knee
deformity or post-traumatic fractures, he said in his conclusion. – by
Susan M. Rapp
Reference:
- Martin A, Cip J, Mayr E, et al. Randomized prospective study
comparing navigated versus non-navigated TKA: 5-year follow up. Paper #2430.
Presented at the 2011 EFORT Congress. June 1-4. Copenhagen, Denmark.
- Mark Widemschek, MD, can be reached at Department of Orthopedic
Surgery, Academic Teaching Hospital, Medical University of Innsbruck,
Carinagasse 47, 6800 Feldkirch, Austria; email:
mark.widemschek@lkhf.at.
- Disclosure: The authors have no relevant financial
disclosures.