Distance of the femorotibial joint gap can be controlled in the modified ligament dependent cut procedure during total knee arthroplasty.
During total knee arthroplasty in fifty consecutive cases, the distal femur and proximal tibia were initially cut. After posterior cruciate ligament excision, the femorotibial joint was expanded by a Tensor/balancer device with 30 inch-pounds of torque (in.lbs) both in extension and flexion, and ligament balancing was obtained in full extension. Then the knee was flexed at 90 degrees, and the femoral rotational axis was decided so that the axis was parallel to the tibial cut surface and the joint gap was the same between extension and flexion. The relationship between the distance of the joint gap expanded by a Tensor/balancer device with 30 in.lbs and the size of the bearing insert was assessed. The results showed that a 24 or 25-mm joint gap expanded by a Tensor/balancer device in full extension was optimal for a 10-mm bearing insert. Therefore, if the resection level of the tibia is set 24 or 25 mm from the femoral cut surface, a 10-mm bearing insert can be used. In 49 cases, the size of the femoral component was one size (4 mm) larger than that predicted based on the bony structure shown in the radiographs of the knee. With this procedure, ligament balancing and optimal joint gap both in extension and flexion can be obtained based on the predicted bearing insert in the knee.
Nagamine
Ryuji
R
Department of Orthopaedic Surgery, Kyushu Rosai Hospital, 1-3-1 Kuzuharatakamatsu, Kokuraminami-ku Kitakyushu-city, Fukuoka, Japan 800-0252. nagamine@kyushuh.rofuku.go.jp
Kondo
Keiichi
K
Ikemura
Satoshi
S
Shiranita
Atsushi
A
Nakashima
Satoshi
S
Ihara
Hidetoshi
H
Sugioka
Yoichi
Y
D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D006801:Humans; D008023:Ligaments, Articular / Q000502:physiology