2017 ISAKOS Biennial Congress ePoster #1604


Intraoperative Analysis of Flexion Kinematics of Osteoarthritic Knees Using CT-Free Navigation

Makiko Okuno, MD, Nishinomiya, Hyogo JAPAN
Takatoshi Morooka, MD, Nishinomiya, Hyogo JAPAN
Fumiaki Imamura, MD, Nishinomiya, Hyogo JAPAN
Shinichi Yoshiya, MD, Nishinomiya, Hyogo, Hyogo JAPAN

Hyogo College of Medicine, Nishinomiya, Please Select, JAPAN

FDA Status Not Applicable


Status of the cruciate ligaments may be a critical factor to induce non-physiologic flexion kinematics in osteoarthritic knees.



Goal of total knee arthroplasty (TKA) is restoration of normal function of the knee. In order to critically evaluate the outcome of TKA, therefore, it is important to understand how the normal function is impaired in knees undergoing TKA. In this study, three-dimensional (3-D) flexion kinematics of the osteoarthiritic knee undergoing TKA was intraoperatively analyzed using CT-free navigate system. Thereafter, relationship between the altered kinematics and clinical/macroscopic characteristics of the knee was examined.


In total, 72 osteoarthritic knees undergoing primary PS TKA ( Aesculap, Tuttilingen, Germany) were included in the study. Surgeries were performed by two of the authors following the standardized procedure using a navigation system. Intraoperative measurement of kinematics during passive flexion was performed using the CT-free navigation system (OrhtoPilot, Aesculap) equipped with special software for 3-D kinematic analysis.
Kinematic analysis using the navigation system
Intra-operative passive flexion kinematics were measured by the Orthopilot? system and analyzed by the dedicated software (OrthoPilot TKA Version4.2 Kobe version). This software allows data acquisition of 3-D kinematics intraoperatively. Kinematic recording was performed both before and after TKA implantation. During the kinematic measurement, the assistant surgeon held the thigh to align it perpendicularly while the operating surgeon gently held the heel and passively moved the knee from full extension to full flexion by inducing unconstrained motion.
In addition, chart review was conducted for preoperative clinical findings of the knee as well as macroscopic findings of the intraarticular structures at surgery.


* Flexion kinematics (Anterior-posterior translation)
Basic feature of anterior-posterior translation during passive flexion was classified into three patterns using the cluster analysis: Group A, posterior femoral translation (rollback) from the initial stage of flexion; group B, small amount of posterior femoral rollback with increasing flexion; group C, no appreciable femoral roll back throughout flexion. Among the 72 knees included in this study, the numbers of the knees classified for the three groups were 21 knees, 34 knees, and 17 knees for Groups A, B, and C respectively.
*Preoperative clinical characteristics
Preoperative clinical findings such as range of motion, limb alignment on weight-bearing radiograph, and clinical score were compared among the groups; however, no significant difference was demonstrated between each of the groups.
* Macroscopic findings of intraarticular structures at surgery
There was no significant difference for severity of cartilage damage between the groups. Regarding the status of the anterior cruciate ligament (ACL), apparent attenuation or disappearance of ACL was noted in 9.5%, 14.7%, and 41.2% of the knees in Groups A, B, and C respectively.


Physiologic flexion kinematics with posterior femoral rollback during flexion was not observed in 51 of the 72 knees (71%) undergoing TKA. Those kinematic abnormalities were not related to the general clinical characteristics such as range of motion and knee alignment. Regarding the relationship between the kinematics and damages of the intraarticular structure, the status of the ACL was significantly correlated with flexion kinematics in which damage of the ACL was related to loss of posterior femoral rollback with flexion. Although function of the posterior cruciate ligament (PCL) has been thought to be a primary factor inducing posterior femoral rollback, loss of ACL/PCL interaction may result in the non-physiologic translation pattern during flexion.