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Semi-constrained posterior stabilized total knee arthroplasty reproduces natural deep knee bending kinematics

Authors :
Takanobu Sumino
Tetsuya Tomita
Kazuomi Sugamoto
Takaharu Yamazaki
Ken Okazaki
Source :
BMC Musculoskeletal Disorders, Vol 21, Iss 1, Pp 1-8 (2020)
Publication Year :
2020
Publisher :
BMC, 2020.

Abstract

Abstract Background The Flexible Nichidai Knee Posterior Stabilized (FNK-PS) system was designed to provide relatively high varus-valgus stabilities without the stem extensions to patients with severe knee joint disorders. This is a combination of a large tibial post and high femoral cam adapted to a PS system. The aim of our study was to analyze the in vivo two-dimensional/three-dimensional registration kinematics of the FNK PS-total knee arthroplasty (TKA) system during deep knee bending. Methods Nineteen knees from 15 total knee arthroplasty (TKA) patients who were able to squat with enough knee flexion were selected. During deep knee bending under weight bearing (WB) and non-weight bearing (NWB) conditions, we quantified range of motion, axial rotation, femoral anteroposterior translation, and post-cam engagement angle. Results The maximum-flexion was significantly different between the two conditions. The mean axial femoral external rotation was 4.8° and 6.2° under WB and NWB conditions, respectively, at 120° flexion. Anteroposterior translation based on bicondylar posterior roll-back patterns was noted with increasing knee flexion. Both the medial and lateral femoral aspects were significantly more posterior during early to mid-flexion. Initial post-cam engagement occurred significantly earlier during flexion under NWB than under WB conditions. Under WB, the timing of the post-cam engagement correlated with the maximum flexion . Conclusions The kinematics of the semi-constrained PS system reproducibly exhibited a mild external rotation with smooth posterior roll-back. This was assisted by the engagement of the large tibial post and high femoral cam during the early phase of flexion.

Details

Language :
English
ISSN :
14712474
Volume :
21
Issue :
1
Database :
Directory of Open Access Journals
Journal :
BMC Musculoskeletal Disorders
Publication Type :
Academic Journal
Accession number :
edsdoj.364afdb2f41044ddb310a09367d21f26
Document Type :
article
Full Text :
https://doi.org/10.1186/s12891-020-3059-1