Navigation of total knee arthroplasty: rotation of components and clinical results in a prospectively randomized study

Abstract

BackgroundNavigation was introduced into total knee arthroplasty (TKA) to improve accuracy of component position, function and survival of implants. This study was designed to assess the outcome of navigated TKA in comparison with conventional implantation with the focus on rotational component position and clinical mid-term results.MethodsIn a prospectively randomized single-blinded approach, 90 patients with primary gonarthrosis were assigned to three different groups. Thirty patients each were assigned to NexGen LPS without and with navigation (groups 1 and 2), and 30 patients to navigation with the Stryker Scorpio PS (group 3). The navigation system used was the imageless Stryker KneeTrac, version 1.0. Clinical outcome was assessed by a blinded observer applying the Knee Society Score (KSS) and a visual analogue scale (VAS) for pain. CT scans and radiographs were conducted prior to and 12 weeks after index surgery.ResultsSeventy-nine patients were available for clinical evaluation at 3 ± 0.4 years follow-up. Four implants had to be revised for early loosening or infection (4.4%). Four patients had died and three patients were not able to follow the invitation for clinical assessment. Functional results in the KSS were significantly lower after navigated TKA. Operation time and incisions with navigation were significantly longer. Significantly less radiological outliers with navigation were found for coronal alignment of the femur, only.ConclusionIn this series, no beneficial effect for navigation in TKA could be shown assessing clinical data, as functional results in the presented series seemed to be lower after first generation navigated TKA. The clinical mid- to long-term value of navigation remains to be evaluated in larger patient series or meta-analyses at longer follow-up.Trial registration numberDRKS 00000430

Patellar denervation for Anterior Knee Pain Management in Knee Arthroplasty

“…13 In this study, we observed that the scores obtained in the KSS and WOMAC questionnaires were significantly better in patients who underwent surgery with PD compared to those without patellar denervation: the former scored, on average, 6 points higher in KSS questionnaire and 6 points less in WOMAC. This is consistent with recent studies that have shown improved joint function in patients submitted to PD, 10,13 indicating a better function of the affected joint. In addition, and considering that both questionnaires also assess referred pain, this may also indicate mild pain relief.…”

Which Factors Increase Risk of Malalignment of the Hip-Knee-Ankle Axis in TKA?

“…They reported patients who underwent navigated TKA had a lower risk of limb and implant malalignment at more than 3°with respect to the mechanical axis and an outlier rate of 12% to 13% for the limb mechanical axis. Despite the accuracy, individual studies have reported an outlier rate of 0% to 29% with navigated TKA for limb mechanical axis [16,17,24,28,29]. This wide variation may be due to the small number of navigated knees (ranging from 32 to 282) included in most of these studies and the fact that most of these cases were part of an early series where surgeon experience might have played a role in the alignment outcome.…”

“…Furthermore, none of these studies have analyzed the causes or risk factors for malalignment. Few [17,24,28] have attributed malalignment to reasons such as error during bone cuts, error during registration, displacement of the infrared arrays during the procedure, and errors that occur during obtaining and measuring postoperative radiographs.…”

The Computer-Aided-Surgery Improved the Accuracy of Femoral Component Rotation in Total Knee Arthroplasty for the Advanced Osteoarthritis with Valgus Deformity

“…Instead of intraoperative judgment of chamfer block in axial plane visually, the surgeon can judge the accuracy of chamfer block under the real-time quantitative feedback of the navigation system. Using post-operative CT scans, several authors have demonstrated significant improvement in the rotational alignment of the femoral component with CAS-TKA [7,8,11,13], however, other researchers have reported no differences between CAS-TKA and conventional TKA [17,[28][29]. The different types of preoperative knee deformity (varus or valgus deformity) seen in their respective study population may be another possible confounding factor.…”

“…The choice of cutting block used to achieve a distal femoral bone cut perpendicular to the mechanical axis of the femur is dependent on the valgus correction angle of the distal femur. Computer-Aided Surgery (CAS) has been reported to provide more accurate bone cuts, more precise component placement in coronal, sagittal and axial planes (within 3 degrees of target component and limb alignments), better restoration of coronal limb alignment and joint line position, and less gap asymmetry [6][7][8][9][10][11][12]. CAS may be advantageous in TKA for valgus arthritic knee because precise cuts of the femur and tibia in conjunction with meticulous soft tissue release should produce more favorable results.…”