Initial experience with custom-fit total knee replacement: intra-operative events and long-leg coronal alignment

Abstract

New technology using magnetic resonance imaging (MRI) allows the surgeon to place total knee replacement components into each patient's pre-arthritic natural alignment. This study evaluated the initial intraoperative experience using this technique. Twenty-one patients had a sagittal MRI of their arthritic knee to determine component placement for a total knee replacement. Cutting guides were machined to control all intraoperative cuts. Intra-operative events were recorded and these knees were compared to a matching cohort of the senior surgeon's previous 30 conventional total knee replacements. Post-operative scanograms were obtained from each patient and coronal alignment was compared to previous studies using conventional and computer-assisted techniques. There were no intra-operative or acute postoperative complications. There were no differences in blood loss and there was a mean decrease in operative time of 14% compared to a cohort of patients with conventional knee replacements. The average deviation from the mechanical axis was 1.2°of varus, which was comparable to previously reported conventional and computer-assisted techniques. Custom-fit total knee replacement appeared to be a safe procedure for uncomplicated cases of osteoarthritis.

Do Patient-specific Guides Improve Coronal Alignment in Total Knee Arthroplasty?

“…Patient-specific instrumentation can be engineered to restore the knee alignment to either the mechanical axis or the kinematic alignment. Several studies [22,33] have been published comparing kinematically aligned patient-specific instrumentation with conventional instrumentation, but these studies have been limited by small sample size, limited radiographic analysis, or lack of a comparable control group. There are no published studies comparing patient-specific instrumentation based on the mechanical axis versus conventional instrumentation.…”

“…Last, we do not report on clinical outcomes such as pain, stiffness, ROM, patient satisfaction, or outcome scoring systems, which may limit the true clinical relevance of the findings in this study. Despite the fact that patient-specific instrumentation has been commercially available for several years, little has been published on this new technology [16,21,22,33]. Three of these articles focused on the results of patient-specific instrumentation based on the kinematic alignment model [16,21,33].…”

“…Despite the fact that patient-specific instrumentation has been commercially available for several years, little has been published on this new technology [16,21,22,33]. Three of these articles focused on the results of patient-specific instrumentation based on the kinematic alignment model [16,21,33]. One study [21] reported on four TKAs performed using kinematic-based patient-specific instrumentation and found intraoperatively that the tibial components were between 3°valgus and 7°varus, but long radiographs were not taken, so overall alignment was not evaluated.…”

“…One study [21] reported on four TKAs performed using kinematic-based patient-specific instrumentation and found intraoperatively that the tibial components were between 3°valgus and 7°varus, but long radiographs were not taken, so overall alignment was not evaluated. In another study [33], the authors reported on 21 consecutive patients who had a TKA performed with patientspecific instrumentation based on the kinematic axis. They found the mean coronal alignment in this group was 1.2°v arus ± 2.4°(range, 6°valgus to 4°varus) but they had no control group for comparison so they compared their results with results of previous studies reporting on coronal alignment between computer-assisted and conventional TKAs.…”

“…Several studies have compared limb and knee alignment of mechanically and kinematically aligned patient-specific instrumentation with conventional instrumentation [22,33]. These studies are limited to small sample size and limited radiographic analysis and neither compared coronal alignment with patient-specific instrumentation based on the mechanical and kinematic axes.…”