2025 ISAKOS Biennial Congress ePoster
The Effects Of The Flexion Gap Setting On Postoperative Outcomes Of Tka Using The Mako Robotic Arm
Shuhei Sugioka, MD, Iga, Mie JAPAN
Masayoshi Okuda, MD, PhD, Yao, Osaka JAPAN
Yuki Kawaguchi, PT, Yao City, Osaka JAPAN
Yasuhito Tanaka, Prof., Kashihara, Nara JAPAN
TOHO Yao Hospital, YAO, OSAKA, JAPAN
FDA Status Cleared
Summary
The present study showed that a 1 mm difference in extension and flexion gap does not affect the flexion angle.
ePosters will be available shortly before Congress
Abstract
【Objective】
In recent years, robotic arm-assisted total knee arthroplasty (RA-TKA) is being introduced. We have been performing Mako robotic arm-assisted TKA since October 2021. In RA-TKA, the gap balance can be freely set during surgery, allowing placement planning of the femoral and tibial components to be performed with high accuracy. We investigated whether there is a difference in clinical outcomes between different joint gaps using the Mako robotic arm.
【Methods】
A retrospective analysis was performed 45 patients (7 males and 38 females, mean age 74.3 years) who underwent Mako RA-TKA for knee osteoarthritis. The patients were classified into two groups: Group A (21 cases, 29 knees) had osteotomies with the same value of medial flexion gap and extension gap, and Group B (24 cases, 29 knees) had osteotomies with a medial flexion gap 1 mm larger than the extension gap. Knee joint range of motion, pain Visual Analogue Scale (VAS), the Forgotten Joint Score-12 (FJS-12), the MOS 36 Short-Form Survey (SF-36), and the Knee injury and Osteoarthritis Outcome Score (KOOS) were compared between the two groups preoperatively, at discharge, 3 months after surgery, and 6 months after surgery. There were no significant differences in preoperative patient factors.
【Results】
The flexion angle did not differ significantly between groups, but the extension angle improved significantly in Group A (-8.3±6.0°→-3.8±3.7°→-2.6±3.5°) until 3 months after surgery and reached its peak. The FJS-12 (Group A: 24.2±16.0→37.3±23.5 Group B: 17.7±11.5 → 26.2 ± 18.2) improved significantly at discharge in both groups. In comparison between the two groups, significant differences were observed only at 3 months after surgery in VAS (exercise), but no significant differences were observed in knee joint range of motion, FJS-12, SF-36, or KOOS at any time.
【Discussion】
Although the flexion gap is usually larger than the extension gap in manual TKA, the use of robotic arm allows for accurate bone resection and minimal soft tissue damage, resulting in little error in the extension and flexion gap. It has been reported that manual TKA improved postoperative flexion angles more markedly than RA-TKA, which was thought to be due to a looser flexion gap. The present study showed that a 1 mm difference in extension and flexion gap does not affect the flexion angle.