2017 ISAKOS Biennial Congress ePoster #1282
Rotational Kinematics Patterns Affect On Postoperative Patient Satisfaction After Posterior Stabilized Total Knee Arthroplasty.
Tatsuhiko Kutsuna, MD, PhD, Toon, Ehime JAPAN
Kazunori Hino, MD, PhD, Toon, Ehime JAPAN
Kunihiko Watamori, MD, Toon, Ehime JAPAN
Seiji Watanabe, MD, Toon, Ehime JAPAN
Hiroshi Kiyomatsu, MD, PhD, Toon-City, Ehime JAPAN
Yasutake Iseki, MD, Toon, Ehime JAPAN
Hiromasa Miura, MD, PhD, Prof., Toon, Ehime JAPAN
Department of Bone and Joint Surgery Ehuime University Graduate School of Medicine, Toon, Shitsukawa, Ehime, JAPAN
FDA Status Cleared
An increasing internal rotation angle of the tibia during the initial knee flexion might be important for obtain better clinical result after posterior stabilized total knee arthroplasty.
Patient satisfaction and knee function after total knee arthroplasty (TKA) has been lower than after a similar procedure, total hip arthroplasty. A partial reason for poor subjective outcomes after TKA may be abnormal kinematics patterns after TKA. The purpose of this study was to analyze rotational kinematic patterns in knees treated with posterior stabilized (PS)-TKA, and to clarify the relationship between the rotational kinematics patterns and patient satisfaction and knee function.
Materials & Methods
This study was a retrospective cohort study. A total of 43 OA knees after primary PS-TKA (NexGen LPS-Flex Fixed Bearing Knee system, Zimmer ) were included in this study; deformed valgus, severe flexion contractures, and highly unstable knees were excluded. We used a computer navigation system and measured knee kinematics after each surgery was completed. A single investigator gently applied a manual range of motion from full extension to flexion. The angle of the internal rotation of the tibia was measured automatically at 0, 30, 45, 60, and 90°, in addition to maximum extension and flexion. We examined the range of motion (ROM) and the 2011 Knee Society Score (2011 KSS) at the final follow up at least 6 months following surgery. Stastical analysis. The difference between the two groups was compared using a non parametric Wilcoxon rank sum test. The analyses were performed with JMP statistical software v8.0 (SAS Institute, Tokyo, Japan). A p-value of < 0.05 was considered significant.
The tibia was internally rotated, (average 5°) at initial knee flexion. However, the kinematics patterns had some variations, and we analyzed the individual cases, focusing on the initial knee flexion from 0-30°. We categorized the post-operative rotational kinematics pattern as one of two types. Type A corresponded to an increased internal rotation angle of the tibia during the initial knee flexion. Type B corresponded to an increased external or an unchanged rotation angle of the tibia. The type A kinematics pattern had better ROM and higher patient specific outcomes than the type B kinematics pattern.
Modern TKA implant has been designed to achieve a reproduction of normal knee kinematics to obtain better patient satisfaction and knee function. However, there were few reports that investigated the relationship between the rotational kinematics patterns at initial knee flexion and patient satisfaction and knee function. In our result, patient satisfaction (screw home like movement) in post-operative rotational kinematics patterns classified as type A had better results than type B. An increasing internal rotation angle of the tibia during the initial knee flexion might be important for obtain better clinical result after PS-TKA.