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TKA navigation yields greater implantation accuracy in level 1 study
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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.