2015 ISAKOS Biennial Congress ePoster #1420
Preoperative Knee Kinematics Impacts Upon Postoperative Knee Kinematics in Total Knee Arthroplasty
Naoki Seito, MD, PhD, Sapporo, Hokkaido JAPAN
Tomohiro Onodera, MD, PhD, Sapporo, Hokkaido JAPAN
Yasuhiko Kasahara, MD, PhD, Sapporo, Hokkaido JAPAN
Eiji Kondo, MD, PhD, Sapporo, Hokkaido JAPAN
Norimasa Iwasaki, MD, PhD, Sapporo, Hokkaido JAPAN
Tokifumi Majima, MD, PhD, Tokyo JAPAN
Hokkaido University, Sapporo, JAPAN
FDA Status Cleared
Summary: The patients who demonstrate medial pivot kinematics pattern after TKA is known to have better clinical results than that of non-medial pivot pattern. In this study we found that preoperative knee kinematics robustly impacted upon the postoperative knee kinematics. These findings will be valuable in strategy to reproduce the medial pivot pattern after TKA.
We have previously reported that patients who demonstrated medial pivot kinematics pattern after total knee arthroplasty (TKA) had better clinical results than that of non-medial pivot pattern. However, it is unclear how preoperative kinematics pattern affects postoperative knee kinematics. The aim of this study was to evaluate the relationship between preoperative and postoperative knee kinematics pattern in TKA.
Materials And Methods
The present study consists of 38 patients with medial osteoarthritis who underwent a primary TKA using a CT-based navigation system from July 2010 to September 2012. All the operations were performed by a single surgeon using a subvastus approach and the same posterior cruciate ligament substituting type (PS type) of prosthesis (Genesis II™ total knee system, Smith & Nephew, Memphis, TN). The proximal tibia osteotomy and the distal femur osteotomy were set on the navigation system perpendicular to the mechanical axis in the coronal plane with 3° tibial posterior inclination in the sagittal plane. The coronal plane ligament imbalance was corrected until the gap imbalance was fewer than 2 mm. This gap balance was checked using a ligament balancer (Smith & Nephew) at 80 N in medial and lateral compartment of the knee. The navigation system was used to measure the flexion gap with the CAS ligament balancer (Depuy, Warsaw, IN, USA) at 90° knee flexion. The amount of external rotation on femoral osteotomy was adjusted by the navigation system with a balanced gap technique. The patella was resurfaced and a lateral release was not performed. Tibial A-P axis of the tibial tray was placed parallel to Akagi’s line. We measured each kinematics pattern immediately after capsule incision (preoperative knee kinematics) and after implantation (postoperative knee kinematics) in TKA. Subjects were divided into two groups based on kinematics patterns: a medial pivot group (group M) and a non-medial pivot group (group N). A chi-square test was used for statistical analysis. P values less than 0.05 were considered significant.
There were 19 knees in group M and 19 knees in group N at preoperative knee kinematics measurement. Nineteen knees in group M at preoperation resulted in 14 knees in group M and five knees in group N at postoperative knee kinematics measurement. On the other hand in group N at preoperation resulted in 2 knees in group M and 17 knees in group N at postoperative kinematics. Preoperative knee kinematics significantly correlated with postoperative knee kinematics (P < 0.01). Our results suggest that preoperative knee kinematics robustly impacted upon postoperative knee kinematics in most cases.
Discussion And Conclusion
In conclusion, this study revealed that a precise bone cut assisted by a navigation system and a modified gap technique could not improve the knee kinematics pattern in most cases. Further technical improvement or a new implant design is required to correct preoperative abnormal knee kinematics in TKA.