Affiliation:
1. Department of Computer Assisted Surgery and Sports Medicine Hospital for Special Surgery New York New York USA
2. Department of Orthopaedic Surgery and Sports Medicine Amsterdam UMC location University of Amsterdam Amsterdam The Netherlands
3. Charité—Universitatsmedizin Berlin Corporate Member of Freie Universität and Humboldt Universität Berlin Germany
4. Medisch Kliniek Velsen, Department of Orthopaedic Surgery and Sports Medicine Velsen‐Noord The Netherlands
Abstract
AbstractPurposeThere is a lack of literature evaluating outcomes of the ligament‐guided approach in medial unicompartmental knee arthroplasty (UKA). An improved comprehension of the distribution of coronal plane alignment of the knee (CPAK) phenotypes and sagittal tibial wear patterns and their associations with patient‐reported outcome measures (PROMs) and implant survivorship could provide insights into its further application in daily practice.MethodsA registry was reviewed for patients with a minimal 2‐year follow‐up who underwent robotic‐assisted, ligament‐guided, medial UKA between 2008 and 2016. Survivorship and postoperative PROMs were collected. CPAK phenotypes and sagittal tibial wear patterns were determined. Survivorship, Knee Injury and Osteoarthritis Outcome Score (KOOS), Kujala and patient satisfaction were compared between phenotypes and sagittal tibial wear patterns.ResultsA total of 618 knees were included at a mean follow‐up of 4.1 [2.0–9.6] years. Four‐year conversion to the TKA survival rate was 98.9% [98.4%–99.3%] and 94.3% [93.3%–95.3%] for all‐cause revision. Patients with preservation of the CPAK phenotype (84.5 ± 14.9, 81.8 ± 15.5, p = 0.033) and restoration of prearthritic coronal alignment (84.1 ± 14.9, 81.7 ± 15.9, p = 0.045) had a significantly higher Kujala score. No other significant differences in survivorship or PROMs were observed between phenotypes or sagittal tibial wear patterns. Additionally, no difference in survival rates was observed between preserved or altered phenotypes.ConclusionThis study demonstrated that preservation of CPAK phenotype and preservation of prearthritic coronal alignment yielded a significantly higher Kujala score. No other significant differences in PROMs or implant survivorship were observed, suggesting that robotic‐assisted, ligament‐guided medial UKA provides equal outcomes for all observed phenotypes and sagittal tibial wear patterns in medial compartment OA as long as preoperative CPAK phenotype is preserved postoperatively.Level of EvidenceLevel III.