2023 ISAKOS Biennial Congress Paper
Intra-Operative Change of Fixed Flexion Deformity in Robotic-Arm Assisted Unicompartmental Knee Arthroplasty
Ahmed A Magan, BM BSc (Hons) MRCS (Eng) FRCS (Eng) Trauma & Orth, London UNITED KINGDOM
Warran Wignadasan, MBBS, BSc (Hons), MRCS, London UNITED KINGDOM
Babar Kayani, BSc (HONS), MBBS, MRCS (Eng), London UNITED KINGDOM
Vishal Rameshlal Rajput, MBBS,DNB orth,MRCS(Edinburgh,UK), Botson, Lincolnshire UNITED KINGDOM
Dia Eldean Giebaly, MBChB, MSc, FRCS, EMBA, London UNITED KINGDOM
Fares S. Haddad, MCh(Orth), BSc, FRCS(Orth), London UNITED KINGDOM
University College London Hospital, London, UNITED KINGDOM
FDA Status Cleared
Summary
This is the first study to use optical motion capture technology to quantify the change in FFD during robotic-arm assisted UKA.
Abstract
Introduction
Unicompartmental knee arthroplasty (UKA) is an effective surgical treatment for patients with unicompartmental knee arthritis. Residual fixed flexion deformity (FFD) may lead to worse functional outcomes, but the change in FFD with UKA remains unknown. The objective of this study was to assess the change in FFD in patients undergoing medial UKA.
Methods
This prospective cohort study included 63 patients with medial compartment arthritis undergo-ing robotic-arm assisted UKA at a single tertiary centre between 2018 and 2022. This study included 30 males and 33 females with a mean age of 62 ± 5.7 years. Patients were divided into four study groups based on the degree of preoperative FFD: < 3 degrees, 3 – 6 degrees, 6-9 degrees, and >9 degrees. Intraoperative optical motion capture technology was used to assess pre- and postoperative FFD. The Oxford Knee Score (OKS) was assessed in all patients be-fore surgery and at one-year follow-up.
Results
This study found statistically significant increase in mean preoperative to mean postoperative FFD for each of the four treatment groups: : < 3 degrees (pre op FFD = 1.53, post op FFD = 0.61 degrees, P = 0.004), 3 - 6 degrees (pre op FFD = 4.94 degrees, post op FFD = 3.71, P = 0.015), 6 – 9 degrees (pre op FFD = 7.96 degrees, post op FFD = 3.63, P < 0.001), >9 de-grees(pre op FFD = 11.63 degrees, post op FFD = 7.18, P value < 0.001). All treatment groups showed a statistically significant improvements from preoperative to postoperative OKS (p<0.001) at one year follow-up. There were no significant differences in OKS between the four treatment groups at one-year follow-up.
Conclusion
This is the first study to use optical motion capture technology to quantify the change in FFD during robotic-arm assisted UKA. The FFD was reduced by approximately half in all four treatment groups with no difference in functional outcomes based on the degree of preoperative FFD. These findings may help to modify existing clinical criteria for medial UKA.