Previous anthropometric studies have reported gender differences in distal femoral morphology. After total knee arthroplasty, females have a higher prevalence of medial or lateral femoral component overhang, which could be responsible for postoperative knee pain and decreased range of motion. Consequently, gender-specific knee prostheses were designed to accommodate female morphology. However, to date, very few studies have investigated the knee morphology of Japanese adults and possible gender differences. The purpose of this study was to examine the distal femoral morphology of Japanese patients, to characterize anatomical differences between men and women, and to evaluate the need to create gender-specific knee prostheses. We evaluated 107 knees in 17 male and 90 female Japanese patients for total knee arthroplasty (TKA)[fig.1]. The medial-lateral (ML) and anteroposterior (AP) dimensions of the knees at different levels evaluated intraoperative measurement, and ML/AP aspect ratios were calculated.Introduction
Material and Methods
MERA Quest Knee System (Quest Knee) is a posterior cruciate ligament–retaining prosthesis considering the anatomical features and lifestyles of the Japanese. As for the anatomical features, we reduced the size of prosthesis and set a smaller interval of sizes because Japanese knees are smaller and flatter than those of Caucasians. As for the lifestyles, we evaluated in vivo patellar tracking during deep knee flexion and the condylar geometry in the axial plane of magnetic resonance imaging. It was found that the patella sank deeply into the intercondylar notch and that the articular surface of the lateral condyle began to curve steeply. We adopted this shape and engraved the lateral condyle deep to reduce the pressure of the patellofemoral joint and to get better range of motion (ROM). For the contact pressure rise in the femorotibial joint by engraving the lateral condyle, the insert was suited to the shape of the femoral component. Furthermore, we increased the thickness of the posterior flange of the femoral component and changed the posterior radius of curvature gradually, and this shape allowed the flexion of 155°. We have used Quest Knee for clinical applications from October 2009. We studied the short-term results of Quest Knee. Between June 2010 and July 2013, the same senior surgeon performed 59 consecutive primary operations with Quest Knee. Forty patients (44 knees) were women, and 14 patients (15 knees) were men. The mean patient age was 72.5 years (range, 59–89 years). All were osteoarthritis knees. Coronal deformity was varus in 58 knees and valgus in one knee. All operations were performed with a measured resection technique, and all patellae were resurfaced. Clinical evaluations were assessed using the Japanese Orthopaedic Association knee rating score (JOA score), and clinical ROM and standing femorotibial angle (FTA) were measured. Additionally, three-dimensional motion analysis of the patellar component during squatting was performed by the image matching method with image correlations.Introduction
Methods
The widespread use of TKA promoted studies on kinematics after TKA, particularly of the femorotibial joint. Knee joint kinematics after TKA, including the range of motion (ROM) and the physical performance, are also influenced by the biomechanical properties of the patella. Surgeons sometimes report complications after TKA involvinganterior knee pain, patellofemoral impingement and instability. However, only few studies have focused specially on the patella. Because the patella bone is small and overlapped with the femoral component on scan images. In addition, the patellar component in TKA is made of x-ray–permeable ultra-high molecular weight polyethylene. It is impossible to radiographically determine the external contour of the patellar component precisely. No methods have been established to date to track the dynamic A computed tomography (CT) and an x-ray flat panel detector system (FPD) were used. FPD-derived post-TKA x-ray images of the residual patellar bone were matched by computer simulation with the virtual simulation images created using pre-TKA CT data. For the anatomic location of the patellar component, the positions of the holes drilled for the patellar component pegs were used. This study included three patients with a mean age of 68 years (three females with right knee replacement) who had undergone TKA with the Quest Knee System and achieved a mean passive ROM of 0 to ≥ 130° after 6 or more month post-TKA. We investigated three-dimensional movements of the patellar component in six degrees of freedom (6 DOF) during squatting and kneeling. Furthermore, we simulated the three-dimensional movement of the patellar component, and we estimated and visualized the contact points between the patellar and femoral components on a three-dimensional model.Introduction:
Methods:
In posterior cruciate ligament-retaining total knee arthroplasty (CR-TKA), a small bone block (bony island) is often preserved to protect the attachment of the posterior cruciate ligament (PCL), which might be troublesome. In contrast, we prefer to resect the tibial plateau completely to facilitate the surgical procedure. However, there is concern over the increase of the flexion gap due to partial detachment of the PCL. The purpose of the present study is to evaluate the influence of bony island resection on the flexion gap. The subjects were 20 consecutive patients who underwent posterior cruciate ligament-retaining total knee arthroplasty for varus osteoarthritis. There were 18 women, two men, with a mean age of 71.8 years (range, 62–82 years). All operations were performed using posterior cruciate ligament-retaining prosthesis (MERA Quest Knee System, Senko Medical Instrument Manufacturing, Tokyo) by the same senior author with a measured resection technique. The knees were exposed with a medial parapatellar approach. The distal femur was cut and the tibial plateau resection was made with preserving the bony island. The central joint gaps in 90° flexion and full extension were measured using a tensioning device (Offset Repo-Tensor, Zimmer, Warsaw, IN) at 40-lb distracting force. Then, after the resection of the bony island, the central joint gaps were measured by the same method. In addition, the posterior tilt of the tibial resection and the depth of the lateral tibial cut were measured.Introduction:
Methods:
There are some reports that the invasive surgery of knee joint replacement repair static and dynamic balance. We investigated the changes in static and dynamic balance and muscle strength in pre- and postoperative of TKA and UKA for the purpose of assessing time dependent improvement. A total of 168 patients (137 TKA; mean age 75.3, 31 UKA; mean age 78.1) were recruited to the study. These patients underwent static and dynamic balance assessment and muscle strength pre operation and 3, 6, 12 months post operation. The parameters of assessment were one leg standing time (open or close eyes), postural sway test (open or close eyes), 3m timed-up-and-go test, maximum stride and Isokinetic muscle strength. We have evaluated both the absolute value and the index which divided the value of the post-operation with the value of pre-operation. Alignment had improved significantly after surgery in TKA and UKA. Isokinetic muscle strength (Fig. 1), one leg standing time with open eyes, 3m timed-up-and-go test (Fig. 2) and maximum stride showed better improvement than pre operation at 3, 6, and 12 months after surgery in TKA and UKA. On the other hand, one leg standing time with close eyes and postural sway test showed no improvement than pre operation at any time after operation (Fig. 3). Butpostural sway test in UKA showed the improvement trend at 3 months after surgery. In contrast, those test in TKA showed no improvement at 3 months after surgery (Fig. 3). Our result showed the improvement of balance function correlated with muscle recovery and improvement of lower limb alignment than equilibrium function after the artificial knee joint replacement surgery. Because one leg standing time with close eyes and one leg postural sway test represent the equilibrium function than other tests. It is interesting that significant difference in the recovery of postural sway in three months after surgery in UKA compared with TKA.
Functional joint stability and accurate component alignment are crucial for a successful clinical outcome after TKA. However, there are few methods to evaluate joint stability during TKA surgery. Activities of daily living often cause mechanical load to the knee joint not only in full extension but also in mid-flexion. Computer navigation systems are useful for intra-operative monitoring of joint positioning and movements. The purpose of this study was to compare the varus-valgus stability between knees treated with cruciate-retaining (CR) and posterior-stabilized (PS) TKA at different angles in the range of motion (ROM) especially in mid-flexion, using the navigation technique. Thirty two knees that underwent TKA with computer navigation technology (precisionN Knee Navigation Software version 4.0, Stryker, Kalamazoo, MI) were evaluated (CR:16; PS:16). The investigator gently applied physiologically allowable maximal manual varus-valgus stress to the knee without angular acceleration, while moving the leg from full extension to flexion, and the mechanical femoral-tibial angle was measured automatically by the navigation system at every 10 degrees throughout the ROM. This measurement cycle was repeated for 3 to 4 times, and maximal varus-valgus laxity was determined as the sum of varus and valgus stress angles for each of the predetermined knee flexion angles. The results of the navigated measurements were used to evaluate varus-valgus instability throughout the ROM and the differences in varus-valgus laxity between pre-TKA (Prior to bone cutting, after navigation registration and suturing of the joint capsule) and post-TKA(After confirming that the TKA components and inserts were firmly placed in an appropriate position, the surgical incision was completely closed). The differences in varus-valgus laxity between the CR and PS groups were compared using the Student's The knees examined showed the greatest preoperative laxity at 20 to 40 degrees of flexion, with no statistically significant difference between the CR and PS groups (See Figure 1). However, postoperative assessment revealed that PS knees had more varus-valgus laxity than CR knees at all ROM angles examined, and the differences were statistically significant in the flexion range of 10 to 70 degrees (See Figure.2). The differences between preoperative and postoperative joint laxity were analyzed separately for the CR and PS groups. After CR-TKA, joint laxity decreased across all degrees of knee flexion. The differences between preoperative and postoperative joint laxity were statistically significant for the flexion range of 110 to 120 degrees (See Figure.3). On the other hand, knees treated with PS-TKA showed an increase in joint laxity for the flexion range of 10 to 90 degrees. The differences between the preoperative and postoperative values were statistically significant for the flexion range of 10 to 20 degrees in PS-TKA (See Figure.4). We successfully evaluated varus-valgus laxity in this study using a navigation system. The results showed that PS knees had greater varus-valgus laxity than CR knees throughout the ROM, and the differences were statistically significant for the flexion range of 10 to 70 degrees. Altogether, we conclude that PS knees have more mid-flexion laxity than CR knees.
Accurate alignment and sizing of the femoral component in total knee arthroplasty (TKA) is important for stability and functional outcomes. In relation to the shape of the distal femur, it has been reported that the medial-lateral (ML) femur width in women is narrower than that in men for the same antero-posterior (AP) length. In addition, it has been noted that the elevation of the anterior condyle in women is lower than that in men. Therefore, in TKA for women, it is suggested that a medial or lateral overhanging femoral component can cause pain or limit the range of motion (ROM). As a result, a gender-specific implant for women has been developed. However, there are few studies addressing the morphological dimensions of the distal shape of the femur in the Japanese population. The objective of this study was to reveal the appropriateness of using gender-specific implant for Japanese women. This study was based on 40 women (40 knees) and 40 men (40 knees) who had primary preoperative osteoarthritis of the knee. The average height was 161.2 cm for men and 149.4 cm for women. The average weight was 68.0 kg for men and 58.5 kg for women. These are significantly different. Resection of the distal femur for TKA was simulated with preoperative computed tomography (CT) data. The ML width on the anterior and distal cut surface, the ML width at the surgical epicondylar axis (SEA) level, the maximum AP length at the medial and lateral condyle, and the AP length after resection were measured. These values were compared between men and women, and compatibility with NexGen LPS-Flex and Gender Solution Femur (GSF) (Zimmer, Warsow, Ind) was evaluated.Introduction
Methods
The efficacy and accuracy of computer navigation systems in total knee arthroplasty (TKA) have been proven in recent years. However, potential disadvantages associated with navigation systems, such as increased surgical time and registration errors, have been reported. Currently, we use a navigation system only for the femoral side. We use the conventional extramedullary guide system for the tibial side (hybrid navigation method) because we have increased the accuracy of tibial positioning in the coronal plane with the conventional system by considering the following key points. (1) Set the extramedullary alignment guide to avoid the rotational mismatch between the proximal part of the tibia and the ankle joint. (2) Insert the tibial component along the AP axis of the resected surface. (3) Remove the protruding bone at the antero-lateral edge of the tibia to obtain the flat, resected surface of the tibia. The purpose of this study was to determine the accuracy of the hybrid navigation method. We compared the postoperative alignment of 60 TKAs implanted using the conventional alignment guide system with 30 TKAs implanted using the hybrid image-free navigation method. The average age was 74.2 (range, 50 to 85) years in the conventional group and 73.6 (range, 51 to 84) years in the hybrid group. The intramedullary alignment guide was used for the femur in the conventional group. The knees were evaluated using full-length, weight-bearing anteroposterior radiographs.Introduction
Methods
