Intraoperative evaluation of total knee replacement: kinematic assessment with a navigation system

Abstract Interest in the kinematics of reconstructed
knees has increased since it was shown that the alteration
of knee motion could lead to abnormal wear and damage to
soft tissues. We performed intraoperative kinematic measurements
using a navigation system to study knee
kinematics before and after posterior substituting rotating
platform total knee arthroplasty (TKA). We verified
intraoperatively (1) if varus/valgus (VV) laxity and anterior/
posterior (AP) laxity were restored after TKA; (2) if
TKA induced abnormal femoral rollback; and (3) how
tibial axial rotation was influenced by TKA throughout the
range of flexion. We found that TKA improved alignment
in preoperative osteoarthritic varus knees which became
neutral after surgery and maintained a neutral alignment in
neutral knees. The VV stability at 0 was restored while AP
laxity at 90 significantly increased after TKA. Following
TKA, the femur had an abnormal anterior translation up to
60 of flexion, followed by a small rollback of 12 ± 5 mm.
TKA influenced the tibia rotation pattern during flexion,
but not the total amount of internal/external rotation
throughout whole range of flexion, which was preserved
after TKA (6 ± 5). This study showed that the protocol
proposed might be useful to adjust knee stability at time
zero and that knee kinematic outcome during total knee
replacement can be monitored by a navigation system.