Joint Gap Kinematics in Posterior-Stabilized Total Knee Arthroplasty Measured by a New Tensor With the Navigation System

Abstract

We clarified the characteristics of joint gap kinematics in PS TKA under physiological and reproducible joint conditions. Our findings can provide useful information for prosthetic design and selection and allow evaluation of surgical technique throughout the range of knee motion that may lead to consistent clinical outcomes after TKA.

Lateral Soft Tissue Laxity Increases but Medial Laxity Does Not Contract With Varus Deformity in Total Knee Arthroplasty

“…1). The center joint gap and the varus angle between the seesaw plate and the platform plate were measured [13][14][15]. The measurements with the tensor were obtained three times by one surgeon (SM), and the average was used for data.…”

Measurement of knee joint gaps without bone resection: “Physiologic” extension and flexion gaps in total knee arthroplasty are asymmetric and unequal and anterior and posterior cruciate ligament resections produce different gap changes

“…We did not control the relative positions of the femur and tibia during the measurements; rather, we allowed the joints to find their natural alignment. To reduce error from creep of the surrounding soft tissues, 19 the joint distraction force was initially applied repeatedly to ''condition'' the tissues.…”

Joint Gap Changes with Patellar Tendon Strain and Patellar Position During TKA

“…1) provided by a ratchet-type hex wrench, which limited applicable force at 40 pounds. The 40-pound distracting force was chosen based on previous studies [12,16] regarding joint gap measurement during surgery and to maintain the integrity of the bone and soft tissues. The width of the joint gap was defined as the center distance between the upper side of the seesaw plate and the underside of the lower plate.…”

“…We used the tensor device developed by Matsumoto et al [16] for measuring the joint gaps. This device consisted of two plates that were connected to the main body by the offset arm.…”

“…Matsumoto et al measured the joint gap using their own tensor device when performing TKA and showed the gap during flexion was smaller with the patella in the reduced position than with the patella in eversion [16]. The knee extensor mechanism (patellar tendon-patella-quadriceps complex) elongates with knee flexion and pressure on the patellofemoral joint changes with the knee flexion angle Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.…”