Effects of Different Posterior Tibial Slopes in Unicompartmental Knee Arthroplasty on the Wear and Function of Prosthesis / 医用生物力学

Objective To establish the three-dimensional (3D) finite element model of unicompartmental knee arthroplasty (UKA) with 3° and 7° posterior tibial slope at different knee flexion angles, and to study biomechanical properties and prosthetic wear of the knee joints with two types of posterior tibia slope and their effects on knee function. Methods Combining CT and MRI images of human knee joints with the 3rd-generation Oxford prosthesis, the finite element UKA model with 3° and 7° posterior tibia slope were established. The 1 kN load was applied to center point of the medial and lateral condyles of the femur to simulate the standing load of human body. The maximum stresses and distributions of the prosthesis and articular cartilage at different knee flexion angles were analyzed. ResultsThe maximum stress of the meniscus liner with 3° posterior tibia slope at 0°, 30°, 60°, 90°, 120° knee flexion angles increased by 28.06%, 68.99%, 19.45%, 21.06% and 53.38%, the distribution area was concentrated from the side of the meniscus liner to the central area, and the stress concentration was obvious at 120° knee flexion. The maximum stress of prosthesis with 3° posterior tibia slope was greater than that with 7 ° posterior tibia slope. The expansion of stress concentration area would cause wear and loosening of the prosthesis, contact stress and concentration area of the articular cartilage would subsequently increase with posterior tibia slope increasing, and stress concentration would be more obvious at high knee flexion angles. Conclusions Tibial prosthesis has the higher stress and greater wear under the condition of 3° posterior tibia slope than 7° posterior tibia slope. The research findings provide theoretical basis for the UKA design in clinic.

Influence of tibial component slope on short-term clinical outcome for Oxford unicompartmental knee arthroplasty / 中华外科杂志

Objective@#To investigate the effects of tibial component slope change after microplasty (MP) Oxford unicompartmental knee arthroplasty (UKA) on short-term clinical outcome.@*Methods@#A total of 116 patients(128 UKAs)underwent UKA in Department of Orthopaedic Surgery of China-Japan Friendship Hospital between January 2014 and December 2015 were retrospectively reviewed. Totally 100 patients (108 UKAs) were finally included in the study. There were 31 males and 69 females, aging from 47 to 90 years (mean 67.2 years). The mean height was (161.9±8.4) cm and the mean body mass index (BMI) was (26.2±3.3) kg/m2. The posterior tibial slope (PTS) at preoperative and postoperative were measured on the lateral radiograph. The postoperative PTS were divided into five groups (<3°, 3° to 5°, 5° to 7°, 7° to 9° and>9°). The Oxford Knee Score (OKS) was recorded. Pearson correlation analysis, ANOVA and t test were used to analyze data.@*Results@#All operations were successfully accomplished and there were no transfusion, infection, thrombus and other complications. There was 1 patient accepted revision because of bearing dislocation. Compared to preoperative, the PTS decreased (6.5°±2.2° vs.9.6°±3.4°) postoperative, there was statistical difference (t=9.053, P<0.01). Only 3 patients were beyond the recommended range (2° to 12°). A total of 82 patients (86 UKAs) were followed up. The follow-up time was 1 to 2.9 years (mean 2 years). The OKS was 43.0±4.1 (mean 31 to 48). The PTS increased in 12 patients (12 UKAs) postoperative, the mean OKS was 40.5±5.2. The PTS decreased in 70 patients (74 UKAs), the mean OKS was 43.4±3.8. There were significant difference in OKS (t=2.347, P=0.021). There were no significant difference in OKS between the five groups. There were positive correlation between postoperative PTS and preoperative PTS (r=0.201, 95%CI: 0.001 to 0.396, P=0.037), there were no correlations between postoperative PTS and hight and BMI. There were negative correlations between OKS and postoperative PTS (r=-0.255, 95%CI: -0.063 to -0.427, P=0.018) and PTS change (r=-0.292, 95%CI: -0.08 to -0.475, P<0.01).@*Conclusions@#Satisfying PTS can be obtained by use of Oxford MP instrumentation. The clinical outcome of the postoperative PTS decreased was relatively better. Too large posterior slope of the tibial implant should be avoided.

Changes in Femoral Posterior Condylar Offset, Tibial Posterior Slope Angle, and Joint Line Height after Cruciate-Retaining Total Knee Arthroplasty

PURPOSE: Changes in the femoral posterior condylar offset (PCO), tibial posterior slope angle (PSA), and joint line height (JLH) after cruciate-retaining total knee arthroplasty (CR-TKA) were evaluated to determine their influence on the flexion angle. MATERIALS AND METHODS: A total of 125 CR-TKAs performed on 110 patients were retrospectively reviewed. Pre- and postoperative PCO, PSA, and JLH were compared using correlation analysis. Independent factors affecting the postoperative flexion angle of the knee were analyzed. RESULTS: The PCO was 28.2+/-2.0 mm (range, 24.5 to 33.1 mm) preoperatively and 26.7+/-1.8 mm (range, 22.2 to 31.2 mm) postoperatively (r=0.807, p0.291). CONCLUSIONS: Although the PCO and JLH did not change significantly after CR-TKA, the PSA decreased by 5.5degrees with a small range of variation. Restoration of the PCO and JLH could promote optimization of knee flexion in spite of the decreased PSA after CR-TKA.

Influence of Posterior Tibial Slope on Stability and Second-Look Arthroscopic Findings after Anterior Cruciate Ligament Reconstruction / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to analyze the influence of posterior tibial slope on stability in clinical and second-look arthroscopic evaluation after anterior cruciate ligament (ACL) reconstruction. MATERIALS AND METHODS: From 2000 to 2011, 124 patients who underwent ACL reconstruction using an allogaft were enrolled in this study. A posterior tibial slope between 0degrees and 4degrees was found in 28 patients (group A), between 5degrees and 9degrees in 64 patients (group B), and greater than 10degrees in 32 patients (group C). We evaluated stability using the Lachman test and a KT-2000 arthrometer. In second-look arthroscopy, grafted tendons were evaluated based on the tension, rupture, and synovial coverage. RESULTS: In clinical evaluation for stability, mean KT-2000 arthrometer and Lachman test at last follow-up showed no statistically significant differences depending on posterior tibial slope. Second-look arthroscopic findings showed no statistically significant difference between groups A and B (p=0.91). However, statistically significant relations were observed between groups A and C (p=0.03), and between groups B and C (p=0.02). CONCLUSION: The results of this study suggest that patients who underwent ACL reconstruction with higher posterior tibial slope (> or =10degrees) have more lax tension in second-look arthroscopy, but not in clinical stability tests.

The Effect of Tibial Posterior Slope on Contact Force and Ligaments Stresses in Posterior-Stabilized Total Knee Arthroplasty-Explicit Finite Element Analysis

PURPOSE: The purpose of this study is to evaluate the effect of change in tibial posterior slope on contact force and ligament stress using finite element analysis. MATERIALS AND METHODS: A 3-dimensional finite element model for total knee arthroplasty was developed by using a computed tomography scan. For validation, the tibial translations were compared with previous studies. The finite element analysis was conducted under the standard gait cycle, and contact force on ultra-high molecular weight polyethylene (UHMWPE) and stresses on lateral and medial collateral ligaments were evaluated. RESULTS: The tibial translations showed similarity with previous studies. As the tibial posterior slope angle increases, the contact stress area increased and was well distributed, and the contact force on UHMWPE decreased overall. However, the maximum contact force in the case for 10degrees case was greater than those for others. The stresses on ligaments were the greatest and smallest in 0degrees and 10degrees cases, respectively. CONCLUSIONS: The higher tibial posterior slope angle leads to the lower contact stress and more extensive stress distribution overall in posterior-stabilized total knee arthroscopy. However, it does not absolutely mean the smallest contact force. The stresses on ligaments increased with respect to the smaller tibial posterior slope angle.

Effect of Decreasing Tibial Posterior Slope on the Extension-Gap during PS-TKA

PURPOSE: To evaluate the effect of decreasing tibial slope on extension gap during posterior stabilized total knee arthroplasty. MATERIALS AND METHODS: One hundred and ten cases of total knee arthroplasty which were done with posterior stabilized implant were included and we divided those into Group I; having flexion contracture (n=35) and Group II; no flexion contracture (n=75), and from each group, we evaluated the relationship between degree of decreased angle of tibial slope and frequency of additional resection of distal femur which was done for compensating insufficient extension gap during total knee arthroplasty and compared frequencies of additional distal femoral resections between 2 parts having more and less degree of decreased angle of tibial slope. RESULTS: In Group I and II, tibial slope decrease were 8.7degrees, 7.4degrees (p=0.145) and frequencies of additional resection were 51.4%, 24% (p=0.005) in average. Comparing 2 parts having more and less degree of decreased angle of tibial slope in each Group, frequencies of additional resection were 44.4%, 58.8% (p=0.505) and 13.2%, 35.1% (p=0.032). CONCLUSION: During posterior stabilized total knee arthroplasty, especially having no preoperative flexion contracture, decreasing tibial slope can be considered as a factor influencing on extension gap by removing greater anterior bone and the estimation of predictable tibial slope decrease through preoperative radiologic findings can be helpful in creating equal flexion and extension gaps.

Effect of the Decrease in Tibial Posterior Slope on the Patellar Height after Total Knee Arthroplasty

PURPOSE: To evaluate the effect of the decrease in posterior slope of the tibia on the patellar height after TKA. MATERIALS AND METHODS: One hundred and fifty three cases of TKA (CR type: 43, PS type: 110) were evaluated to measure the posterior slope of the tibia and the patellarheight on lateral radiographs of the knee before and after surgery. Then, we analyzed a correlation between two measurements. RESULTS: The decrease in tibial posterior slope and patellar height was average 6.6 degrees and 1.4mm, there was a weak correlation (r= -0.293, p=0.000), as more decrease in tibial slope, less decrease in patellar height. Comparing CR group with PS group, the decrease of posterior slope of tibia and patella height was average 3.5 vs 7.8 degrees (p=0.000) and 2.2 and 1.2 mm (p=0.146) respectively. There were also correlations (r=-0.438, p=0.003 vs r=-0.228, p=0.017) between two decreases. CONCLUSION: It is considered that the decrease in tibial posterior slope is one of elements influencing in patellar height, and through preoperative radiological examination, estimation of expected decrease in tibial posterior slope is helpful in preserving patellar height in TKA.

A Radiologic Study of the Reference Line for Measuring Posterior Slope Angle on Lateral View of the Knee / 대한정형외과학회잡지

PURPOSE: This study evaluated the radiological reference line of the posterior slope angle on the lateral view of a plain knee radiograph. MATERIALS AND METHODS: The lateral view of the plain knee and whole tibia radiographs were analyzed from thirty seven patients (fifty-two cases) who had undergone total knee arthroplasty. The posterior slope angle was measured on the lateral view of the tibia. On the lateral view of the knee, the posterior slope angle was measured with reference to the proximal tibial anatomical axis, the proximal tibial anterior cortical line, the proximal tibial posterior cortical line and the proximal fibular anatomical axis. These values were compared with the posterior slope angle measured on the whole tibia lateral view. RESULTS: The posterior slope angle, which was measured by the anterior cortical line as a reference line, was tilted slightly anteriorly to that measured by the whole tibial lateral anatomical axis (0.15 degree in average; anterior slope 3.95- posterior slope 5.57 degree). This difference was smallest among that of the measured angle by the other reference lines (p<0.001). CONCLUSION: The anterior cortical line of the proximal tibia appears to be the most reliable reference line for measuring the posterior slope angle on a knee lateral radiograph after TKA.

Relationship Between ground Surface and Tibial Posterior Slope at Erect Posture in Total Knee Arthroplasty

PURPOSE: To evaluate the perioperative changes of the relationship between tibial posterior slope and ground surface and the factors which influence the perioperative changes of the relationship between tibial posterior slope and ground surface following total knee arthroplasty. MATERIALS AND METHODS: Between Sept. 2005 and Feb. 2006, 94 consecutive primary total knee arthroplasty with posterior cruciate ligament-retaining type performed in 50 patients by one surgeon. Posterior slope of the proximal tibia resection in extramedullary guide was fixed at 5degrees. All the retrieved patients wore a 90degrees ankle brace and stood on the ground during radiographic examination. We prospectively analyzed the measurement of tibial posterior slope angle, the angle between tibial posterior slope and ground surface and the angle between a midline from 1st metatarsal shaft to talus and ground surface on preoperative and postoperative 2-weeks radiographs. RESULTS: On preoperative radiograph, average of tibial posterior slope angle is 11.3degrees and 11.5degrees in right and left knee, respectively. Angle between tibial posterior slope and ground surface is an average of 8.8degrees and 9.5degrees in right and left knee, respectively. On postoperative 2-weeks radiograph, tibial posterior slope angle is an average of 9.3degrees and 9.1degrees in right and left knee, respectively. Angle between tibial posterior slope and ground surface is an average of 6.2degrees and 6.4degrees in right and left knee. There are significant differences between tibial posterior slope angle and the angle between tibial posterior slope and ground surface on preoperative and postoperative 2-weeks radiograph (p<0.05). CONCLUSION: According to ankle lateral angle, it is possible that tibial posterior slope associated with the ground surface may decrease at erect posture in total knee arthroplasty. This may lead to overly decrease tibial posterior slope associated with the ground surface at comfortable erect posture in total knee arthroplasty.

Radiographic Analysis of the Tibial Axis on the Antero-posterior and Lateral view of Knee

PURPOSE: The purpose of this study is to evaluate the use of plain knee films in assessing the position of tibial component after total knee arthroplasty. MATERIALS AND METHODS: Plain radiological antero-posterior(AP) and lateral view of tibia of 51 adults (mean age: fifty-years old) were taken. On AP view, the medial angles between tibia plateau and mechanical, anatomical and proximal anatomical axis of tibia were measured, and then correlation of each angle and the angle between the tibia plateau and anatomical axis were assessed. On lateral view, the posterior angle formed between the medial tibial plateau and anatomical, proximal anatomical axis, anterior and posterior cortex of proximal tibia were measured, and then correlation of each angle and the angle between the medial tibial plateau and anatomical axis were assessed. RESULTS: On tibial AP view, both axes had significant correlation(p<0.05) with the anatomical axis. The anatomical axis of proximal tibia was closest to it. On lateral view, all three axes had significant correlation(p<0.05) with anatomical axis. Among these, the anterior cortex of proximal tibia was closest to it. CONCLUSION: The position of the tibia component and posterior slope after total knee arthroplasty can be measured on plain knee X-rays using anatomical axis and the anterior cortex line of proximal tibia.

A study on the size of condyle and the posterior slope of the articular eminence in patients with temporomandibular joint disorders

0.05). 3. There were no statistically significant differences in the condylar ratio between the groups (p>0.05). 4. There were no statistically significant differences in the discrepancies of the left and right ramus length measurements between the groups (p>0.05). 5. The relative size of condyle to fossa in the group of temporomandibular disorders was smaller than that in the normal group (p<0.05).

Influence of the Posterior Slope of the Tibial Component on the Maximal Flexion after Total Knee Arthroplasty

To evaluate the effect of tibial cut with posterior slope in total knee arthroplasty(TKA) surgery on the flexion of the knee, 41 knees(32 patients) with varying degree of the posterior slope were retrospectively reviewed at more than 1 year after operation. Does sloping the tibial cut iurface rnore posteriorly promote increasing of maximal flexion of the knee by elimination of excessive tenaion of the posterior cruciate liga ment The degree of the posterior slope was radiographically measured, awi the change of the degree of the maximal flexion between preoperative and postoperative period was clinimlly measured with a goniometer at the latest follow up more than 1 year after operation. Comparison of the results demonstrated significantly larger degree of rqaximal flexion for the knees that had tibial cut with the degree of the posterior slope, 5 degrees or rnore (p<0.05). We concluded that 5 degrees or more posterior slope in proxirnal tibial cut is one of the important fact()r which could achieve increased flexion of the knee after TKA operation.