Minimal invasive and computer assisted total knee replacement compared with the conventional technique: a prospective, randomised trial

Abstract

Minimal invasive surgery (MIS) in total knee replacement (TKR) has been favoured by several authors and the industry and is asked for by the patients. Computer assisted surgery (CAS) is proposed to support the surgeon in terms of postoperative leg alignment and implant orientation. To prove the hypothesis that MIS in TKR fastens early rehabilitation compared to the standard approach and that CAS-MIS in TKR improves accuracy in implant position compared to the freehand MIS and freehand standard technique, we performed a prospective, randomised short-term trial which was approved by the local ethic committee. In total, 90 patients underwent TKR. The conventional group (n = 30) underwent conventional TKR, the MIS group (n = 30) underwent MIS-TKR without navigation, the CAS-MIS group (n = 30) underwent TKR using navigation and the MIS approach. Groups were comparable regarding patients' specific parameters. The length of incision in extension was significantly lower in the MIS (13.2 cm) and CAS-MIS technique (12.9 cm) compared to the conventional technique (17.3 cm) (P < 0.01). Knee Society and WOMAC Score were similar in all three groups after 1, 6 and 12 weeks, no significant differences were seen between groups at any point of time. Postoperative deviation of the mechanical leg axis was significantly better in the CAS-MIS group compared to the conventional group and the MIS one (P < 0.05). The clinical relevance of our results is that the benefit of the minimal invasive approach in TKR is still not proven and navigation improves postoperative accuracy of leg alignment and component orientation. Our study shows that for the group of patients included there is no statistically significant difference in early rehabilitation between MIS and the conventional approach based on the Knee Society and WOMAC Score. Using the CAS technique restoration of leg axis was more accurate.

Does Minimally Invasive Total Knee Arthroplasty Improve Isokinetic Torque?

“…reported as improved in the long term [4,11,21], improved only in the short term [15,18,27], or similar [24,25,30,37]. The same has been observed with respect to radiographic findings (leg alignment and/or component alignment).…”

Does Minimally Invasive Surgery Improve Short-term Recovery in Total Knee Arthroplasty?

“…A varus/valgus malalignment greater than 3°influences the longevity of the prosthesis [32]. We found no differences between the groups in terms of the analyses of component angles.…”

The accuracy of two different extra-medullary tibial cutting guides for posterior tibial slope in total knee arthroplasty

“…Similarly, several authors did not find any benefit of navigation system over extramedullary guides in terms of getting desired posterior slope. [18,19] In our study, we think that low accuracy of both cutting systems is a result of surgeon bias to avoide damage to the insertion point of posterior cruciate ligament.…”