Patient satisfaction after total knee arthroplasty (TKA) has been lower than after a similar procedure, total hip arthroplasty. Poor subjective outcomes after TKA may be partially explained by abnormal kinematics patterns after TKA. The purpose of this study was to analyse rotational kinematics patterns in knees that had undergone posterior stabilized (PS)-TKA, and to clarify the relationships between rotational kinematics patterns and patient satisfaction, as well as between rotational kinematics patterns and knee function. A total of 49 osteoarthritis knees after primary PS-TKA (NexGen LPS-Flex fixed bearing knee system) were included in this study; deformed valgus, severe flexion contractures, and highly unstable knees were excluded. We used a computer navigation system and measured knee kinematics after each surgery was completed. A single investigator gently applied a manual range of motion from full extension to flexion. The angle of the internal rotation of the tibia was measured automatically at 0º, 30º, 45º, 60º, and 90º, along with maximum extension and flexion. We categorized the post-operative rotational kinematics patterns for individual cases, focusing on the initial knee flexion from 0–30º. Type A corresponded to an increased internal rotation angle of the tibia during the initial knee flexion (screw home-like movement). Type B corresponded to an increased external or an unchanged rotation angle of the tibia. We examined the range of motion (ROM) at 6 months after surgery and assessed the 2011 Knee Society Score (2011 KSS) at ≥1 year following surgery. Statistical analysis. The difference between the two groups was compared using a Wilcoxon rank sum test. Analyses were performed with JMP statistical software v8.0 (SAS Institute). A p-value of <0.05 was regarded as significant.Background
Materials & Methods
Correct alignment is important for a successful result after total knee arthroplasty (TKA). During most activities of daily living, the knee is loaded not only in full extension but also in mid-flexion. However, there are few methods to evaluate mid-flexion varus-valgus alignment, despite its clinical significance. Computer navigation systems are useful for intra-operative monitoring of joint positioning and movements. Knee ligaments contribute to induce kinematics of the joint. It is likely that the presence of posterior cruciate ligament has some effects on kinematics throughout flexion. The purpose of this study was to evaluate changes in the varus–valgus alignment of the femoral–tibial mechanical axis in each flexion angle before and after TKA by using a navigation system, and to evaluate varus–valgus kinematic patterns throughout flexion, and compare preoperative and postoperative changes of kinematic patterns in CR-TKA and PS-TKA procedures. Forty knees that underwent TKA with computer navigation system were evaluated (CR-TKA 20; PS-TKA 20). CR and PS TKRs were implanted in alternating sequence. The investigator applied manual mild passive knee flexion, while moving the leg from full extension to flexion and the varus-valgus angle of femoral-tibial mechanical axis was measured automatically by the navigation system at every 10 ° throughout flexion. We classified kinematic patterns in the varus–valgus direction throughout flexion.Introduction
Material and Method
Total knee arthroprasty (TKA) is an excellent treatment with osteoarthritis of the knee joint. The acquisition of joint stability after TKA is one of the most important factors to improve the patient's quality of life. Deep flexion of knee joint is often demanded in daily life, and stability in flexed knee position is also important. But there were few papers reporting about laxity in flexed knee position. This study aimed to analyze influence of pre-operative alignment on post-operative varus-valgus joint laxity in TKA. We investigated the varus-valgus laxity of knee joint throughout flexion intra-operatively before and after prosthetic implantation. A total of 20 knees underwent TKA using posterior-stabilised (PS) type component by the measured resection method were included in this study. The varus-valgus joint laxity of knee was measured using an intra-operative navigation system at every 10 ° throughout the range of movement under general anesthesia. We examined the correlations between the pre-operative femorotibial angle (FTA) and varus-valgus joint laxity by method of least squeres. We divided the patients group into two populations according to pre-operative FTA. Large FTA group had more than or equal to 186 °of pre-operative FTA. Small FTA group had less than 186 °pre-operative FTA. T- test was performed between those populations.Introduction
Methods
The purpose of this study was to analyze rotational kinematic patterns in knees treated with either cruciate-retaining (CR) or posterior-stabilized (PS) total knee arthroplasty (TKA), using an intra-operative navigation technique, and to clarify the factors that affect of the rotational kinematics and the difference rotational kinematics patterns between CR- and PS- TKA. A total of 35 knees (35 patients) were included in this study, deformed valgus, sever flexion contractures, and highly unstable knees were excluded. These knees were allocated to CR (NexGen CR-Flex) or PS (NexGen PS-Flex) implants and underwent TKA with a computer navigation technique (precision N Knee Navigation Software v4.0; Stryker). There was no significant difference in pre-operative parameters between CR- and PS-TKA group: age, femorotibial angle (FTA), and chondylar twist angle (CTA). We measured two points during surgery. First, the skin incision was made and subcutaneous tissue was exposed. The joint capsule was temporality closed by three or four strand suture. Second, after the surgery was completed with satisfactory alignment and soft tissue balance, immediately following wound closure the measurement procedure was repeated. The surgeon gently applied a manual range of motion from full extension to flexion. The angle of internal rotation in tibia to the functional plane of tibia and femur was measured automatically at max extension, 0, 30, 45, 60, 90 degrees, and max flexion throughout the passive knee motion.Purpose
Methods
