National Hospital Organization Kanmon Medical Center, Japan
Dr. Takatomo MINE was born in Fukuoka, Japan. He got his bachelor degree from Yamaguchi University School of Medicine. He got his Ph.D. (Dr. of Medical Science) degree at Yamaguchi University School of Medicine. He is currently an Associate Professor in the Department of Orthopedic Surgery, Yamaguchi University. He is the Director of Orthopedic Surgery & Rheumatology at Kanmon Medical Center, Yamaguchi and also a member of various associations: Japanese Orthopedic Association(1985), The Central Japan Association of Orthopedic Surgery & Traumatology(1985), International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine(2014), Japanese Society for Regenerative Medicine(2015), Japanese Society for Cartilage Metabolism(2017) and many other. He has published around 35 articles in various International Journals in the field of Orthopedics.
Background: Stair stepping motion and standing & sitting motion from a chair are important in daily living, similar to gait. It is important to understand in vivo kinematics of patient’s with total knee arthroplasty during stair-stepping and standing & sitting motion from chair. The purpose of this analysis was to estimate in vivo knee motion in stair stepping and standing & sitting motion from a chair, and determine if this unique knee prosthesis function as designed.
Methods: A total of 20 patients implanted with Bi-Surface PS were assessed in stair-stepping. 15 patients were assessed in standing & sitting from chair. The Bi-Surface PS knee is a posterior-cruciate substitute prosthesis with a unique ball-and-socket joint in the mid-posterior portion of the femoral and tibial components. Patients were examined during stair stepping and standing & sitting motion from a chair motion using a 2-dimensional to 3-dimensional registration technique.
Results: In stair-stepping, the kinematic pattern in step up was a medial pivot, in which the level of anteroposterior translation was very small. In step down, the kinematic pattern was neither a pivot shift nor a rollback. From minimum to maximum flexion, anterior femoral translation occurred slightly. In standing & sitting from a chair, from minimum to 30° knee flexion, anterior femoral translation occurred slightly. From 30° knee flexion to maximum flexion, the kinematic pattern was a medial pivot and rollback.
Conclusion: It became clear in this study that the joint’s stability during stair-stepping was affected by the design of the femorotibial joint rather than Post/Cam engagement or the Ball & Socket joint. In standing & sitting from a chair, the unique knee prosthesis functioned as designed.