Range of motion (ROM) is one of the important factor for better functional outcome after total knee arthroplasty (TKA). In posterior cruciate ligament (PCL) retaining (CR) TKA, adequate PCL function is suggested to be important for better kinematics and ROM. However, intraoperative assessment of PCL function is relatively subjective, thus more objective evaluation is required to improve the functional outcomes after TKA. In clinical practice, tibial posterior sagging sign is well known to indicate PCL deficiency. Hence, we hypothesized that intraoperative femorotibial antero-posterior (AP) changes at 90° of flexion indirectly reflected the PCL function and associated with postoperative maximum flexion angles in CR TKA. The purpose of this study was to investigate the correlation between intraoperative femorotibial AP changes at 90° of flexion and postoperative maximum flexion range in navigated CR TKA. Between March 2014 and March 2015, forty patients with varus osteoarthritis underwent primary TKA. All of the cases were using same types of implant (Triathlon; Stryker Orthopedics, Mahwah, NJ, USA), with an image-free navigation system (Stryker 4.0 image-free computer navigation system; Stryker). PCL was retained and cruciate substituting (CS) inserts were used in all cases. The mean age at the time of surgery was 71.7 ± 6.8 years old (ranging: 62 – 85). The mean follow-up was 10.9 ± 6.4 months. After minimum release of medial and lateral soft tissue, resection of anterior cruciate ligaments, and protection of PCL, registration and kinematic measurements were performed prior to bone resection. The kinematic measurements were performed again after implantation. The center of proximal tibial and distal femur were defined during registration. The point of proximal tibia was projected to the mechanical axis of femur and the distance between the projected point and the distal femur at 90° of flexion were measured and defined as femorotibial AP position. Distal relative to the center of distal femur indicates as minus, and proximal relative to the point indicates as plus. The correlation between the intraoperative changes of AP position and postoperative maximum flexion angles were investigated.Introduction
Methods
Recently, kinematic aligned total knee arthroplasty (TKA) has gained interest for achieving better clinical outcomes over mechanical aligned TKA. The primary goal of kinematic aligned TKA is to position the femoral and tibial components so that the angles and levels of the distal and posterior femoral joint lines and the tibial joint line are each restored to the patient's natural alignment, and not to a neutral limb alignment that is unnatural for most patients. Despite good clinical outcomes reported at short to mid-term follow-up, surgeons should know reasons why this method is useful and safe surgery and carefully assess the long-term outcomes until this new technique is settled as standardized procedure for TKA. The main purpose of the present study was to compare postoperative radiography and clinical scores following kinematic and mechanical aligned TKA. Sixty TKAs—30 kinematic and 30 mechanical aligned—were performed in patients with varus-type osteoarthritis using a navigation system. Using postoperative double-leg and single-leg standing long leg radiographs, joint line orientation angle to the floor, conventional mechanical axis (cMA), and true mechanical axis (tMA; line from hip center to the lowest point of calcaneus) were compared between the two groups. One-year after surgeries, range of motion and the patient-derived score of the 2011 Knee Society Score (2011 KSS), which includes four categories: symptoms, patient satisfaction, patient expectations, and functional activities, e.g., walking/standing, standard activities, advanced activities, and discretionary activities, were compared between the two groupsPurpose
Methods
Total knee arthroplasty (TKA) is a successful technique for treating painful osteoarthritic knees. However, the patients' satisfaction is not still comparable with total hip arthroplasty. Basically, the conditions with operated joints were anterior cruciate ligament (ACL) deficient knees, thus, the abnormal kinematics is one of the main reason for the patients' incomplete satisfaction. Bi-cruciate stabilized (BCS) TKA was established to reproduce both ACL and posterior cruciate ligament (PCL) function and expected to improve the abnormal kinematics. However, there were few reports to evaluate intraoperative kinematics in BCS TKA using navigation system. Hence, the aim in this study is to reveal the intraoperative kinematics in BCS TKA and compare the kinematics with conventional posterior stabilized (PS) TKA. Twenty five consecutive subjects (24 women, 1 men; average age, 77 years; age range, 58–85 years) with varus osteoarthritis undergoing navigated BCS TKA (Journey II, Smith&Nephew) were enrolled in this study. An image-free navigation system (Stryker 4.0 image-free computer navigation system; Stryker) was used for the operation. Registration was performed after minimum medial soft tissue release, ACL and PCL resection, and osteophyte removal. Then, kinematics including tibiofemoral rotational angles from maximum extension to maximum flexion were recorded. The measurements were performed again after implantation. We compared the kinematics with the kinematics of paired matched fifty subjects who underwent conventional posterior stabilized (PS) TKA (25 subjects with Triathlon, Stryker; 25 subjects with PERSONA, ZimmerBiomet) using navigation statistically.PURPOSE
Materials and Methods
