Research progress of tibial-graft fixation methods on anterior cruciate ligament reconstruction / 中国修复重建外科杂志

OBJECTIVE@#To review the studies about the tibial-graft fixation methods on anterior cruciate ligament (ACL) reconstruction, in order to provide clinical reference.@*METHODS@#The literature about the tibial-graft fixation methods on ACL reconstruction at home and abroad was extensively reviewed, and the factors that affect the selection of fixation methods were summarized.@*RESULTS@#The knee flexion angle, graft tension, and graft fixation device are mainly considered when the tibial-graft was fixed on ACL reconstruction. At present, the graft is mainly fixed at 0°/30° of knee flexion. The study shows that the knee joint is more stable after fixed at 30°, while the incidence of knee extension limitation decrease after fixed at 0°. In terms of graft tension, a good effectiveness can be obtained when the tension level is close to 90 N or the knee flexion is 30° to recover the affected knee over-restrained 2 mm relative to the healthy knee. In terms of the graft device, the interference screw is still the most commonly used method of tibial-graft fixation, with the development of all-inside ACL reconstruction in recent years, the cortical button fixation may become the mainstream.@*CONCLUSION@#Arthroscopic reconstruction is the main treatment of ACL rupture at present. However, there is no optimal fixation method for the tibial-graft, the advantages and disadvantages of each fixation methods need to be further studied.

Construction and simulation mechanical analysis of dynamic knee joint finite element model based on CT image / 中国骨伤

OBJECTIVE@#To construct a dynamic knee joint finite element model based on CT image data and verify the validity of the model. To provide a simulation model and basic data for biomechanical research of the knee joint by further finite element analysis.@*METHODS@#The CT data of a healthy male knee joint was selected. With the help of Mimics 19.0 and Hypermesh 12.0 software, a high simulation finite element model of knee joint was established following steps, including geometric reconstruction, reverse engineering, meshing and material characterization. The dynamic knee flexion model was generated by determining the boundary conditions and torque loading, and the validity of themodel was confirmed. The biomechanical changes of the tibiofemoral and patellofemoral joints under different knee flexion angles were analyzed by applying the loads (500 N) to the finite element model during knee flexion.@*RESULTS@#A finite element model of knee joint was established based on CT images and anatomical characteristics. The model included three-dimensional elements such as bone, ligament, cartilage, meniscus and patellar retinaculum. The different finite element models of knee flexion states were produced by applying different torques after establishing boundary conditions. According to equivalent conditions (knee flexion 30 degrees, quadriceps tendon under 200 N stretch), the peak stress value of patella was 2.209 MPa and the average Mises stress was 1.132 MPa; the peak stress value of femoral trochlear was 1.405 MPa and the average Mises stress was 0.936 MPa. The validity of the model was proved by the difference between the model and previous studies of 1% to 13.5%. Dynamic model loading showed that the Mises stressof tibiofemoral joint decreased with the increase of knee flexion angle, while the Mises stress of patellofemoral joint was positively correlated with knee flexion angle. The Mises stress of cartilage stress planes at different knee flexion angles was significantly different(<0.05).@*CONCLUSION@#The finite element model established in this study is more comprehensive and can effectively simulate the biomechanical characteristics of dynamic knee joint, which provides support for further simulation mechanics researches of the knee joint.

Intentionally Increased Flexion Angle of the Femoral Component in Mobile Bearing Unicompartmental Knee Arthroplasty

PURPOSE: The purpose of this study was to determine the results of mobile bearing unicompartmental knee arthroplasty (UKA) with an intentionally increased flexion angle of the femoral component in patients requiring high flexion. MATERIALS AND METHODS: We investigated 45 knees treated by UKA. Clinically, we measured the range of motion (ROM) and the American Knee Society (AKS) score preoperatively and at final follow-up and investigated complications. Radiologically, we measured the flexion angle of the femoral component, the posterior slope angle of the tibial component, the femorotibial angle and mechanical axis of the limb postoperatively. RESULTS: The ROM was increased from 123° preoperatively to 139° at the final follow-up. The AKS knee and function scores increased from 59 and 68, respectively, preoperatively to 94 and 96, respectively, at the final follow-up. The flexion angle of the femoral component was 9.1°, and the posterior slope angle of the tibial component was 8.6°. There was one case of bearing dislocation in the largest femoral flexion angle case. CONCLUSIONS: The results might reflect the positive effect of an increased flexion angle of the femoral component up to 10° on ROM in mobile bearing UKA, which would contribute to better quality of life after UKA especially in populations requiring deep knee flexion.

Effect of knee flexion angles during maximum isometric hip extension / 体力科学

The purpose of this study was to examine the effects of knee flexion angles during maximum isometric hip extension. Ten healthy men performed maximum isometric hip extension in prone position at 15° and 90° knee flexion. Then, the hip extension torque was measured, and electromyographic (EMG) data were obtained from the biceps femoris long head, semitendinosus, semimembranosus, adductor magnus, and gluteus maximus muscles. The EMG data were full-wave rectified and integrated (IEMG). The IEMG values obtained during the measurement of isometric hip extension were normalized with the values collected at 90° knee flexion (normalized IEMG [NIEMG]). The hip extension torque at 15° knee flexion was significantly greater than that at 90° knee flexion. The NIEMG values from the hamstrings at 15° knee flexion significantly increased compared with those at 90° knee flexion. Meanwhile, the NIEMG values from the gluteus maximus at 90° knee flexion were significantly greater than those at 15° knee flexion. However, the NIEMG values from the adductor magnus did not significantly differ between 15° and 90° knee flexion. These results indicate that the hamstrings effectively generate contracting force during isometric hip extension and at knee extended position because its fiber length was close to the optimal length.

Effect of Posterior Femoral Condylar Offset and Posterior Tibial Slope on Maximal Flexion Angle of the Knee in Posterior Cruciate Ligament Sacrificing Total Knee Arthroplasty

PURPOSE: To evaluate the effect of femoral condylar offset and posterior tibial slope on maximal flexion angle of the knee in posterior cruciate ligament (PCL)-sacrificing total knee arthroplasty (TKA, Medial-Pivot Knee System). MATERIALS AND METHODS: Forty-five knees in 35 patients who could be followed up more than 1 year after PCL-sacrificing TKA were evaluated retrospectively. We measured and analyzed the preoperative and postoperative maximal flexion angle, posterior femoral condylar offset difference, posterior femoral condylar offset ratio difference, and tibial slope. RESULTS: The mean maximal flexion angle after TKA was 118.44degrees+/-9.8degrees and significantly related to postoperative tibial slope (11.78degrees+/-6.2degrees) in correlation analysis (R=0.451, p=0.002). There was no statistical relationship between the postoperative maximal flexion angle and the posterior femoral condylar offset difference (3.24+/-3.862 mm, R=0.105, p=0.493) and posterior femoral condylar offset ratio difference (0.039+/-0.029 mm, R=-0.163, p=0.284). CONCLUSIONS: The maximal flexion angle of the knee after PCL-sacrificing TKA was significantly related to the postoperative tibial slope. Therefore, posterior tibial slope can be considered as a factor that affects maximal flexion angle after PCL-sacrificing TKA.

Comparative Study of the Postoperative Maximal Flexion Angle in PCL-substituting TKAs: Conventional PS vs. High-flex PS / 대한정형외과학회잡지

PURPOSE: This study was performed to compare the postoperative maximal flexion angle (MFA) of standard PCL-substituting (PS) prosthesis with that of high-flexion PS prosthesis after total knee arthroplasty (TKA). MATERIALS AND METHODS: A total of 81 patients (133 knees) were enrolled in this study. Sixty-eight primary bilateral TKAs were performed in 34 consecutive patients. The bilateral TKAs were performed in a staged sequential manner, with a standard PS prosthesis in one knee and a high-flexion PS prosthesis in the contralateral knee. We also analyzed the results of another 47 patients as several control groups, and this consisted of standard or high-flexion PS total knee prostheses in the bilateral TKAs, and standard or high-flexion PS total knee prostheses in the unilateral TKAs. The patients were clinically assessed with the Knee Society scoring system and the MFA was measured with a goniometer. RESULTS: At the last follow up, the mean postoperative MFA of the 34 patients operated with the combination of different prostheses was 131.6+/-10.4degrees for high-flexion prosthesis side and 131.6+/-9.5degrees for standard prosthesis side respectively. There was no statistically significant difference. On comparing with the results of the 47 patients in the control group, no statistically significant difference in the mean postoperative MFA was found between the groups. CONCLUSION: We found no significant differences between the high-flexion PS prosthesis and the standard PS prosthesis in the postoperative MFA.

Divergence of Femoral interference screw versus Knee Flexion Angle during Endoscopic ACL Reconstruction

The endoscopic single-incision technique using interference fit screws to secure patellar tendon-bone plugs in the femoral and tibial tunnels has been very popular method for ACL reconstruction. However, several potential complications has been reported such as violation of the posterior wall of the femoal tunnel, laceration of graft during femoral screw insertion, protrusion of the tibial bone block distally due to a lengthy graft and more frequently divergence of the femoral interference screw. We performed 56 consecutive endoscopic ACL reconstruction. In Groi.p I, femoral tunnel drilling were performed at 70-80 degrees of knee flexion. In Group 11, they were done at $5 degrees of knee flexion. Postoperative radiographic analysis of bone-interference screw divergence angle shows 5.9 degrees in AP view, 6.21 degrees in Lateral view in Group I and 3.14 degrees, 3.35 degre.s in Group II respectevely. In conclusion, Bone-interference screw divergence can be decreased with less knee flexion about 45 degree during preparing femoral tunnel.

Minimum Flexion Angle of the Knee Joint during Femoral Tunneling and Interference Screw Fixation in Endoscopic ACL Reconstrution / 대한정형외과학회잡지

Isometric positioning of the ACL graft is an important consideration in successful reconstruction of the ACL-deficient knee. The purpose of this study is to get a certain guideline in the endoscopic one-tunnel technique of anterior cruciate ligament reconstruction by measuring the skin angle and determine the degree of minimum flexion of the knee joint during femoral tunneling and interference screw fixations. To get the guide lines, first we get the tibial tunnel angle parallel to the Blumensaat's line from fully extended lateral knee joint radiography. Secondly measure the differences between angles of the femur-tibia shaft and anterior thigh-leg skin. Then measure the minimum femur-tibia flexion angle does not perforated the posterior cortex of the distal femur during femoral tunneling. Intraoperative measuring the angle between interference screw guide pin and tibial tunnel to get the parallelism of the femoral tunnel and interference screw. The results were as follows; The average femur-tibia shaft angle with 30degrees anterior thigh-leg skin angle was 30.2+/-1.75degrees, with 45degrees was 45.2+/-1.23degrees, with 60degrees was 61.9+/-4.23degrees, with 75degrees was 78.6+/-2.62degrees, with 90degrees was 97.8+/-3.96degrees. Predetermined sagittal tibial tunnel vector on the 0degrees extension knee joint lateral radiographs were applied to the several knee joint dynamograms. The mean minimum flexion angle of the femur-tibia shaft that doesn't perforate the posterior cortex of the femur was 45+/-1.58degrees (male), 44.5+/-4.97degrees (female). The average angle between interference screw guide pin and tibial tunnel was 23.0+/-2.23degrees. The findings of the present study suggest that anterior thigh-leg skin angle can be used instead of the true femur-tibia shaft angle. Less knee flexion angle makes good arthroscopic view during the tibio-femoral tunneling and interference screw fixation.