Dariusch Arbab1, Pia Reimann2, Martin Brucker3, Bertil Bouillon4, Christian Lüring5. 1. Department of Orthopedic Surgery, Klinikum Dortmund, Member Faculty of Health Witten/Herdecke University, Beurhausstraße 40, 44137 Dortmund, Germany. Electronic address: darbab@gmx.de. 2. Ruhr University Bochum, Universitätsstraße 150, 44801 Bochum, Germany. 3. Department of Orthopedic Surgery, Klinikum Dortmund, Beurhausstraße 40, 44137 Dortmund, Germany. 4. Department of Traumatology and Orthopedic Surgery, Cologne-Merheim Medical Center (CMMC), University of Witten/Herdecke, Ostmerheimer Str. 200, 51109 Cologne, Germany. Electronic address: bouillonb@kliniken-koeln.de. 5. Department of Orthopedic Surgery, Klinikum Dortmund, Beurhausstraße 40, 44137 Dortmund, Germany. Electronic address: christian.luering@klinikumdo.de.
Abstract
Background: Incorrect positioning and malalignment of total knee arthroplasty (TKA) components can result in implant loosening. Restoration of neutral alignment of the leg is an important factor affecting the long-term results of TKA. The aim of our retrospective study was to compare mechanical axis in patients with conventional and patient-specific TKAs. Methods: 232 patients who underwent TKA between January 2013 and December 2014 were included to compare postoperative mechanical axis. 125 patients received a patient-specific TKA (iTotal CR®, Conformis) and 107 a conventional TKA (Triathlon®, Stryker). Standardized pre- and postoperative long-leg standing radiographs were retrospectively evaluated to compare the two patient cohorts. Results: 113 (90%) radiographs of patient-specific TKA and 88 (82%) of conventional TKA were available for comparison. The preoperative deviation from neutral limb axis was 9.0° (0.1–27.3°) in the patient-specific TKA cohort and 8.2° (0.2–18.2°) in the conventional TKA group. Postoperatively the patient-specific TKA group showed 3.2° (0.1–8.4°) and the conventional TKA cohort 2.3° (0.1–12.5°) deviation. However, the rate of ± 3° outliers from neutral limb axis was 16% in the patient-specific TKA cohort and 26% in the conventional TKA group. Conclusions: Patient-specific TKA demonstrated fewer outliers from neutral leg alignment compared to conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.
Background: Incorrect positioning and malalignment of total knee arthroplasty (TKA) components can result in implant loosening. Restoration of neutral alignment of the leg is an important factor affecting the long-term results of TKA. The aim of our retrospective study was to compare mechanical axis in patients with conventional and patient-specific TKAs. Methods: 232 patients who underwent TKA between January 2013 and December 2014 were included to compare postoperative mechanical axis. 125 patients received a patient-specific TKA (iTotal CR®, Conformis) and 107 a conventional TKA (Triathlon®, Stryker). Standardized pre- and postoperative long-leg standing radiographs were retrospectively evaluated to compare the two patient cohorts. Results: 113 (90%) radiographs of patient-specific TKA and 88 (82%) of conventional TKA were available for comparison. The preoperative deviation from neutral limb axis was 9.0° (0.1–27.3°) in the patient-specific TKA cohort and 8.2° (0.2–18.2°) in the conventional TKA group. Postoperatively the patient-specific TKA group showed 3.2° (0.1–8.4°) and the conventional TKA cohort 2.3° (0.1–12.5°) deviation. However, the rate of ± 3° outliers from neutral limb axis was 16% in the patient-specific TKA cohort and 26% in the conventional TKA group. Conclusions: Patient-specific TKA demonstrated fewer outliers from neutral leg alignment compared to conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.
Entities:
Keywords:
Component malalignment; Hip–knee–ankle angle; Neutral mechanical axis; Patient-specific implants; Total knee arthroplasty; Total knee replacement
Authors: Michael T Freehill; Jack W Weick; Brent A Ponce; Asheesh Bedi; Derek Haas; Bethany Ruffino; Chris Robbins; Alexander M Prete; John G Costouros; Jon Jp Warner Journal: J Shoulder Elb Arthroplast Date: 2022-05-06