The purpose of this study is to report the outcome of navigation-assisted cruciate-retaining total knee arthroplasty (TKA) using one type of cemented, second-generation, floating-platform (FP), mobile-bearing system. We retrospectively reviewed 42 patients (51 knees) who underwent cruciate retaining TKAs using e.motion-FP prostheses under navigational guidance. The preoperative diagnosis was osteoarthritis in all knees except one rheumatoid arthritis. There were 2 men (2 knees) and 40 women (49 knees) with a mean age of 64.0 ± 4.7 years (range, 51 – 76 years) at the time of index surgery. The mean follow-up was 120.0 months (range, 106 – 126 months). Clinical and radiographic results as well as mechanical survival rate of this type prosthesis were investigated at a mean follow-up of 10 years.Background
Methods
Knee joint should be aligned for reconstruction of the function in Total Knee Replacement(TKR). Although a surgeon try to correct the alignment of a knee joint, sometimes varus/valgus alignment has been tried in order to reconstruct function of knee joint. As a result, the varus or valgus alignment affects to ligaments and soft tissue, and the contact condition is changed between femoral component and tibial insert. One of important factor, wear characteristics of an implant can be changed due to the contact condition. In this study, we performed static contact tests from extension to flexion in varus and valgus to define the effect to contact condition when the alignment is varus or valgus. LOSPA TKR femoral component #6 and Tibial insert #5 manufactured by Corentec Co., Ltd. were used as test specimens. The tests have performed with adapting ASTM F2777–10 ‘Standard Test Method for Evaluating Knee Bearing (Tibial Insert) Endurance and Deformation under High Flexion’. The test set like as Fig. 1. The load is applied at 7:3 ratio of lateral-medial by adapting gait analysis. The 5° of jig is used to compare the result in neutral, varus and valgus. The fuji films were used in tests were scanned, and the results were analyzed the compressed area and contact stress as angles of flexion in neutral stance and varus/valgus from scanning. The tests were performed 5 times per each for a reliability.Introduction
Methods
Management of the patella with poor bone stock remains a challenge in revision total knee arthroplasty (TKA). The purpose of this study was to evaluate the results of a novel surgical technique in which widely available wires and acrylic bone cement are used in the reconstruction of a deficient patella. Twenty-eight patients (30 knees) underwent revision TKA in which a deficient patella was treated with an onlay-type prosthesis and bone-augmenting procedure, using transcortical wiring. The technique was indicated when the thickness of remnant patella was less than 8mm with variable amounts of the peripheral rim. The remaining patellar height ranged from 3.2mm to 7.3mm. Follow-up was available for all patients with a mean of 36.6 months (range, 24 to 55 months).Background
Methods
A stem extension improves fixation stability of a tibial component. We need caution not to contact the tibial cortex with an offset adaptor. A symmetric tibial stem design often requires the component's re-positioning with negative effects. Therefore, the objective of this study was to validate clinical efficacy of a tibial baseplate with asymmetric stemmed position (TB-ASP) using aligning outlier rate. We hypothesized that TB-ASP design will be better aligned without unessential offset adaptor than a tibial baseplate with symmetric stemmed position (TB-SSP). TB-ASP was designed based on the anthropometric standard model (58 female cadavers, 54.7±11.4 years)(Figure 1.). To validate the stem position, 3D bone models of 20 OA patients (71.8±7.2 years) was reconstructed. All virtual surgery has done by one surgeon with consistent surgical procedure for the analysis criteria. An analysis of TB-ASP's aligning outlier was proceeded by following steps; 1) aligning tibial baseplate to the line from medial 1/3 tuberosity to the center of PCL, 2) selecting tibial baseplate's size for maximal bone coverage without problematic overhang, 3) trying to displace tibial baseplate and stem extension(120mm long) not to contact tibial cortex. A case invading tibial cortex was considered to be an outlier. The ratio using offset adaptor was compared to those of TB-SSP. Statistical analysis was performed using paired t-test.Introduction
Methods
We sought to determine the 10-year survivorship of single-radius, posterior-stabilized total knee arthroplasty (TKA) in Asian patients. We also aimed to determine whether the long-term clinical and radiographic results differed between patients with and without patellar resurfacing. This retrospective study included 148 (115 patients) consecutive single-radius, posterior-stabilized TKAs. Ten-year survivorship analysis was performed using the Kaplan-Meier method with additional surgery for any reason as the end-point. Furthermore, long-term clinical and radiographic results of 109 knees (74%; 84 patients) with more than a 10-year follow-up were analyzed. Ten-year survivorship and long-term outcomes after surgery were determined, and outcomes were compared between patients with and without patellar resurfacing.Introduction
Materials and Methods
A large proportion of patients with osteoarthritis of the knee, present with bilateral symptoms at the outpatient department. A simultaneous total knee arthroplasty (TKA) procedure is available for such patients. The first operation in a simultaneous surgery may provide information to the operator to determine component size, soft tissue balancing, and estimate gap size for the second operation, while the second team usually conducts an operation in a confined space on the contralateral side during closure for the first operation, which can disturb cooperation during the second operation and may lead to more intra-operative surgical errors. We hypothesized that the circumstances of the two consecutive operations of a simultaneous bilateral TKA are different, could lead to different outcomes of overlapping bilateral TKAs. We therefore addressed the following research questions to determine whether there would be differences in short-term clinical outcomes, radiographic results, and implanted component size between the two sides A retrospective review of 451 consecutive patients, who underwent simultaneous bilateral TKA between January 2011 and April 2012, was conducted. Bilateral TKAs were performed with the senior surgeon conducting the main procedure (from skin incision to implantation of first prosthesis until prior closure of the first knee) on the right side first and subsequently the left side with a second team. At 1 year after surgery, clinical outcome scores (the Knee Society Knee and Function scores, WOMAC score), radiologic findings were evaluated and clinical results as postoperative blood loss, operation time were compared between bilateral sides.Introduction
Methods
The safety implications of achieving high flexion after TKA and the use of high flexion prostheses remain issues of concern. It is possible that different designs have different clinical and radiological results and complications, such as, early aseptic loosening. However, little information is available on the clinical results of TKAs performed using single-radius, high-flex posterior stabilized design. Accordingly, this study was undertaken to document results of single-radius, high-flex posterior stabilized TKAs with minimum 7-year follow-up. From April 2003 to February 2006, 308 patients (455 knees) underwent TKA using single-radius, high-flex posterior stabilized design and among those patients, 251 patients (388 knees) included in this study who were able to be followed up for a minimum 7 year. Clinical results were evaluated using Knee Society Knee scores (KSKS) and Knee Society Function scores (KSFS) at last follow-up. The passive knee flexion was measured using a goniometer before and after surgery. The survival rate of the implants and implant-specific complications such as osteolysis or loosening were investigated. The osteolysis or loosening around the components was recorded according to the Knee Society Radiological scoring System.Background:
Methods:
Soft-tissue balancing is crucial in total knee arthroplasty, but proper release of medial collateral ligament is a challenging procedure. It has been well recognized that medial gap tends to be more tight than lateral gap in varus knees after surgery. The purpose of this study is to investigate the incidence and predictable factors of medial tibial bone remodeling following navigation-assisted total knee arthroplasty. One hundred and sixty-six consecutive patients (221 knees) who underwent navigation-assisted total knee arthroplasty and followed during a minimum of 1 year were included in this study. Radiographic examination including anteroposterior and lateral view of both knees were performed at a regular follow-up schedules of 6 weeks, 3 months, 6 months, 1 year and thereafter, annually after surgery. An independent investigator identified the presence of medial tibial bone remodeling at each follow-up. All information on potential factors affecting medial tibial remodeling were retrieved and classified into 2 types (patient- and surgery-related).Background and Purpose
Materials and methods
We aimed to analyze the clinical results of the patients according to joint line change who underwent navigation assisted cruciate ligament retention type mobile bearing total knee arthroplasty. From September 2004 to January 2006, cruciate ligament retention type mobile bearing total knee arthroplasties using navigation system(Orthopilot®, Aesculap) were performed for 50 knees in 45 patients (2 men, 43 women). The mean follow up period was 46(39~55) months and the mean age was 65. There was one case with rheumatoid arthritis and all other were degenerative arthritic cases. All surgeries were performed using navigation system. Proximal tibia resection was performed at the sclerotic level of medial tibial plateau. The distance from the lowest point of lateral tibial plateau (registered point) to the proximal resection plane was measured. Clinical outcome were compared between joint line elevation with more than 3 mm(20cases) and less than 3mm (30cases). The mean joint line elevation was 1.93 mm (range −1~5mm). There were no significant difference in the clinical results according to the joint line change (p>
0.05). It may be suggested that the change of joint line in the range of −1 to 5mm in cruciate ligament retention type mobile bearing total knee arthroplasty result in satisfactory clinical outcome.
Several reports suggest that the clinical transepicondyle axis which is known as the transverse flexion axis of knee rotation most consistently recreates a balanced flexion space and normal patella-femoral tracking. However the problem is that it is difficult to find the exact location of both femoral epicondyles intraoperatively. We suggest a method to determine femoral external rotation which parallel to the T-E axis using the femoral extramedullary(EM) system. By definition, T-E axis is the line across each epicondyle and knee center, which is perpendicular to the mechanical axis of the femur in the coronal plane. Mechanical coronal plane perpendicular to mechanical sagittal plane is represented by the plane made of three points; femoral head center, lateral femoral epicondyle and knee center. T-E axis is parallel to the coronal plane, therefore if we position the distal femoral block parallel to the mechanical coronal plane, the position of distal femoral block should be parallel to the T-E axis. If the EM system is in its correct position sagittally and coronally, the T-E axis can be traced automatically. Determination of femoral external rotation which parallel to the transepicondylar axis using the EM system could be one of the useful method to determine the external rotation of the femoral component and it will also imrove the patello-femoral tracking.
Achieving the correct amount of femoral component rotation has become the basic objective of surgical techniques in total knee arthroplasty and this can be done either with a measured resection technique or indirectly by flexion/extension gap equalization technique. We demonstrated the variabilities of the reference axes (PCA, WSL, TEA) when soft tissue tension was managed intraoperatively by navigation system. The mean angle of transepicondylar line, Whiteside’s line, posterior condylar line from the proximal tibia resection plane were 1.29 ± 3.67 (mean ± SD; range 7 to 10.5), 3.90 ± 4.17 (mean ± SD; range 3 to 15.5), −4.03 ± 2.71 (mean ± SD; range 9.5 to 1.0) respectively. Coefficient of variation(CV(%); std/mean × 100) were 283, 106, 67 respectively. Out of the 3 reference axes widely used for femoral component rotation, angles from proximal tibia resection plane to posterior condylar line showed the least range of variance.
