Background: The goal of the current prospective randomised radiological study was to determine the accuracy of conventional and computer-assisted femoral component implantation in surface arthroplasty (SRA).

Methods: The standard implantation of SRA started at author’s institution in 2004; the learning curve lasted one year. From January 2006 have authors available a kinematic navigation system „Ci’ (DePuy International Ltd, Leeds, UK) for navigation of the femoral component of SRA „ASR’ (DePuy International Ltd, Leeds, UK). We analysed on standard radiographs the femoral component positioning after 30 conventionally instrumented (Group 1) and 30 navigated (Group 2) SRA femoral components. Posterolateral approach was used in all cases. The average age of 42 men and 18 women during surgery was 54? 8 (44–64) years; body mass index was 26,3? 3,7 (21,5–39,1) kg/cm2. We evaluated: varus or valgus orientation, horizontal femoral offset, and translation of the component.

Results: The varus-valgus positioning was more accurate in Group 2 (p < 0,05). The tendency to implant the femoral component in mild valgus position (2,8° in Group 1 compared to 2,1° in Group 2), more distally and ventrally in the femoral neck (in Group 1) and with femoral offset increase (4,8mm in Group 1 compared to 3,4mm in Group 2) was found. The femoral offset was restored more accurately in the navigated group (p < 0,05). The difference in component translation in relation to the femoral neck between both groups was statistically significant (p < 0,05) – it was more precise in the navigated group. No notching of the femoral neck was observed in both groups.

Conclusions: It is possible to achieve very accurate positioning of the femoral component with use of the ASR? manual tripod aiming device. But the navigation system enables a more accurate insertion of the femoral component. This benefit clearly weigh against an additional time cost of about 10 minutes because of navigation.

Introduction: The most critical step in the ACL reconstruction is placement of the femoral and tibial tunnels into which the graft is secured. The purpose of this prospective randomised study was to assess biomechanical, radiographic and functional results after single-bundle anterior cruciate ligament (ACL) reconstruction using navigation system.

Materials and Methods: 80 patients were treated for chronic rupture of the ACL. They were involved in a prospective randomized double-blinded study. All patients gave informed consent. 40 patients underwent ACL reconstruction using OrthoPilot navigation system (Group 1) and in other 40 patients was the surgery done by standard manually targeting technique (Group 2). The anterior laxity was measured using a KT-1000 arthrometer. Femoral and tibial tunnel position was evaluated radiologically according to the method described by Bernard/Hertel and Harner, respectively. The questionnaire-based Lysholm scale was included to compare functional state in both groups. The follow-up was at least 2 years.

Results: The knees in Group 1 were as stable as those in Group 2 during the arthrometer testing with lower value of dispersion. The postoperative Lysholm score had the same value in both groups. Statistical differences exist between anterior-posterior femoral tunnel placement when comparing the navigated and standard technique; in Group 1 were found out more exact results. No significant complications were observed.

Conclusions: Used computer kinematic system improves accuracy of the antero-posterior femoral tunnel placement. It also decreases dispersion of biomechanical stability values. This device renders the procedure more reliable and may so reduce the rate of revision surgery.