In vivo kinematics of cruciate-retaining total knee arthroplasty after a change of polyethylene insert configuration

Shotaro Watanabe; Tetsuya Tomita; Ryuichiro Akagi; Atsuya Watanabe; Takaharu Yamazaki; Takahiro Enomoto; Ryosuke Nakagawa; Seiji Kimura; Seiji Ohtori; Takahisa Sasho

doi:10.1016/j.asmart.2020.11.002

In vivo kinematics of cruciate-retaining total knee arthroplasty after a change of polyethylene insert configuration

Asia Pac J Sports Med Arthrosc Rehabil Technol. 2020 Dec 31:24:1-8. doi: 10.1016/j.asmart.2020.11.002. eCollection 2021 Apr.

Affiliations

¹ Department of Orthopaedic Surgery, Graduate School of Medical and Pharmaceutical Sciences, Chiba University, Center for Preventive Medical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba, 260-8677, Japan.
² Department of Orthopedic Biomaterial Science, Osaka University, Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
³ Department of Orthopaedic Surgery, Graduate School of Medical and Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, Chiba, 260-8677, Japan.
⁴ Department of Orthopaedic Surgery, Eastern Chiba Medical Center, 3-6-2 Okayamadai, Togane, Chiba, 283-8686, Japan.
⁵ Department of Information Systems, Saitama Institute of Technology, 1690 Fusaiji, Fukaya, Saitama, 369-0293, Japan.

Abstract

Background: To investigate in vivo kinematics of total knee arthroplasty (TKA) with the introduction of a mildly constrained (MC) type of polyethylene (PE). We compared the knee kinematics with a reported pattern after surgery using the same component with a conventionally constrained (CC) type of PE.

Methods: Finite element analysis (FEA) was performed to examine different peak stress distribution of both types of PE. For in vivo study, patients who underwent cruciate-retaining TKA using a total knee system with MC-PE were included. Fluoroscopic surveillance was used to measure the weight-bearing deep knee bend (squatting) using a two-dimensional/three-dimensional (2-D/3-D) registration technique.

Results: FEA analysis revealed the edge loading of the femoral component on PE in CC but not in MC. During the study period, 42 patients underwent TKA with MC-PE. Among them, 13 agreed to participate in the present study. In vivo kinematics analysis found that starting from an average external rotation of femur being 7.1° at 0° of flexion, the rotation slightly decreased to 6.8° at 10° of flexion, then increased with increasing knee flexion until it reached 10.8° at 80° of flexion, and finally decreased to 9.8° at 100° of knee flexion. The results indicate a modest medial pivot pattern. Although the overall pattern was similar for both MC-PE and CC-PE, a slight difference was observed. MC-PE showed a slight internal rotation of 0.3° from 0 to 10° of knee flexion, whereas CC-PE showed a gradual increase of external rotation in this range.

Conclusions: Change of configuration from CC to MC did not substantially affect in vivo kinematics of knees after TKA. Considering the theoretical wider range of allowance of rotation, MC-PE is easier for knee surgeons to use.

Keywords: Configuration; Finite element analysis; Fluoroscopy; Kinematics; Total knee arthroplasty; Two-dimensional/three-dimensional registration.