Effect of tibial prosthesis riser length on knee biomechanics after unicompartmental knee arthroplasty / 中国组织工程研究

BACKGROUND:Unicompartmental knee arthroplasty can effectively treat severe unilateral knee osteoarthritis.It has been found that posterior tibial cortical fracture is prone to occur after unicompartmental knee arthroplasty.The fracture begins at the keel groove of tibial osteotomy.The tibial prosthesis riser length affects the biomechanical results of the knee joint after unicompartmental knee arthroplasty. OBJECTIVE:To investigate the effect of tibial prosthesis riser length on knee biomechanics in unicompartmental knee arthroplasty,and to find out the relationship between prosthesis riser length and anterior and posterior tibial diameters of patients. METHODS:Computed tomography image data and commonly used unicompartmental prostheses were selected from a 37-year-old healthy female with no history of knee disease.A natural knee joint model was established and a unicompartmental prosthesis model was built.Eight different lengths of tibial prosthesis risers were established,with a minimum length of 31 mm and a maximum length of 34.5 mm in 0.5 mm increments,for comparison with the commonly used hospital prosthesis riser length of 33.2 mm.The material of the femoral component and tibial disc was cobalt-chromium-molybdenum alloy,and the tibial spacer was ultra-high molecular weight polyethylene.The biomechanical changes of the knee joint were observed using finite element analysis software loaded with 1000 N over the femur. RESULTS AND CONCLUSION:(1)The tibial stress was minimal at a tibial prosthesis riser length of 33 mm;the anterior cruciate ligament stress was minimal;the lateral meniscus stress was minimal,and the femoral prosthesis stress was minimal.The remaining components were less stressful.(2)The subject's medial tibial plateau anterior-posterior diameter length was 53 mm,and by calculating the ratio,the optimal ratio of tibial prosthesis riser length to anterior-posterior tibial diameter should be about 62%.If it is lower than this value,aseptic loosening of the prosthesis may occur,and if it is higher than this value,fracture of the bone cortex at the anterior-posterior end of the tibia may occur.

Effect of varus and valgus angles of tibial prosthesis on short-term outcome of fixed bearing unicompartmental knee arthroplasty / 中国组织工程研究

BACKGROUND:Previous studies on the effects of valgus and varus angles of tibial component on short-term postoperative outcomes after mobile bearing unicompartmental knee arthroplasty have been reported in and outside China.However,there are few reports on the effect of the valgus and varus angles of tibial component on short-term postoperative outcomes after fixed bearing unicompartmental knee arthroplasty. OBJECTIVE:To investigate the effect of valgus and varus angles of tibial component on short-term clinical outcomes in patients with medial knee osteoarthritis undergoing fixed bearing unicompartmental knee arthroplasty. METHODS:120 patients(122 knees)who underwent fixed bearing unicompartmental knee arthroplasty for medial knee osteoarthritis in Department of Orthopedic Surgery,Affiliated Hospital of Xuzhou Medical University from August 2020 to January 2023 were selected as the study subjects.Two physicians measured the varus angle of femoral prosthesis,valgus and varus angles of tibial prosthesis,flexion and extension angles of femoral prosthesis,and posterior inclination angle of tibial prosthesis after unicompartmental knee arthroplasty based on postoperative X-ray.After excluding the influence of the other three angles,the measurement results of the tibial component varus angle were divided into three groups:<-2°,-2° to 2°,>2°,which were denoted as groups 1,2,and 3,respectively.The range of knee motion,the hospital for special surgery knee score,the American knee society score,and forgotten joint score were recorded and compared before and after the operation. RESULTS AND CONCLUSION:(1)A total of 120 patients(122 knees)were enrolled in this study.They were divided into three groups according to the size of the valgus and varus angles of the tibial prosthesis after operation:37 patients in the first group,60 patients in the second group,and 23 patients in the third group.There was no significant difference between the three groups in terms of baseline information such as age,gender,and side of surgery(P>0.05).(2)Patients were followed up for 3-30 months after arthroplasty.(3)The hospital for special surgery knee score of the second group was higher than that of the first group(P=0.015)and the third group(P=0.012).The American knee society score of the second group was significantly higher than that of the first group(P=0.014)and the third group(P<0.001).The forgotten joint score of the second group was higher than that of the first group(P=0.033)and the third group(P=0.016).(4)After fixed bearing unicompartmental knee arthroplasty,when the valgus angle of tibial prosthesis was-2° to 2°,which can achieve better short-term clinical results,the degree of prosthesis self-realization is higher.

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.

Progress in the method of tibial prosthesis rotation alignment in total knee arthroplasty / 中国修复重建外科杂志

Objective: To summarize the methods of tibial prosthesis rotation alignment in total knee arthroplasty, and provide reference for clinicians to select and further study the methods of tibial prosthesis rotation alignment. Methods: The advantages and disadvantages of various tibial prosthesis rotation alignment methods were analyzed and summarized by referring to the relevant literature at home and abroad in recent years. Results: There are many methods for tibial prosthesis rotation alignment, including reference to relevant anatomical landmarks, range of motion (ROM) technique, computer-assisted navigation, and personalized osteotomy. The inner one-third of the tibial tuberosity is a more accurate reference anatomical landmark, but the obesity, severe knee deformity and dysplasia have impacts on the precise placement of the tibial prosthesis. ROM technique do not need to refer to the anatomical landmark of the tibia, and aren't affected by landmark variation. It can be used for severe knee valgus deformity and the landmarks that are difficult to identify. However, it may cause internal rotation of tibial prosthesis. Computer- assisted navigation and personalized osteotomy can achieve more accurate alignment in sagittal, coronal, and rotational alignment of femoral prosthesis. However, due to the lack of reliable anatomical landmarkers related to tibia fixation, it is still controversial whether it can help the alignment of tibial prosthesis rotation. Conclusion: The surgeon should master the methods of rotation and alignment of tibial prosthesis, make preoperative plans, select appropriate alignment methods for different patients, and achieve individualization. Meanwhile, several anatomical landmarkers should be referred to properly during the operation, which can be used to detect the correct placement of tibial prosthesis and avoid large rotation error.

Morphometry of the Cut Surface of the Proximal Tibia for Total Knee Arthroplasty in Korea / 대한정형외과연구학회지

PURPOSE: To provide the morphometric data about the Korean proximal tibia to design a total knee prosthesis for Korean population. MATERIALS AND METHODS: We measured morphologic data from the proximal part of the tibia from 60 knees of 30 male and 30 female cadavers. The 3D images were reconstructed from the data obtained by computed tomography scanning from femoral head to ankle joint. These image were processed as a ideal tibial resection surface which was made during a total knee arthroplasty operation. Then, antero-posterior lengths, medio-lateral lengths and aspect ratios of the cut surface were measured. Measurements were analyzed and compared with those of five popular total knee prosthesis models. RESULTS: The average medio-lateral length, lateral antero-posterior length, aspect ratio of male was 79.4 +/- 3.8 mm, 39.6 +/- 5.0 mm, 49.8 +/- 5.1% respectively. And that of female was 70.4 +/- 3.7 mm, 34.3 +/- 3.6 mm, 48.8 +/- 4.7% respectively. Component size of medio-lateral length of 65~85 mm and lateral antero-posterior length of 30~45 mm, would be required for the Korean population. Aspect ratios were correlated to antero-posterior lengths positively (p < 0.05). CONCLUSION: No prostheses had fulfilled all the requirements for Korean knees in this study. These data could be used for design the optimal components for Korean.

Morphometry of the Cut Surface of the Proximal Tibia for Total Knee Arthroplasty in Korea / 대한정형외과연구학회지

PURPOSE: To provide the morphometric data about the Korean proximal tibia to design a total knee prosthesis for Korean population. MATERIALS AND METHODS: We measured morphologic data from the proximal part of the tibia from 60 knees of 30 male and 30 female cadavers. The 3D images were reconstructed from the data obtained by computed tomography scanning from femoral head to ankle joint. These image were processed as a ideal tibial resection surface which was made during a total knee arthroplasty operation. Then, antero-posterior lengths, medio-lateral lengths and aspect ratios of the cut surface were measured. Measurements were analyzed and compared with those of five popular total knee prosthesis models. RESULTS: The average medio-lateral length, lateral antero-posterior length, aspect ratio of male was 79.4 +/- 3.8 mm, 39.6 +/- 5.0 mm, 49.8 +/- 5.1% respectively. And that of female was 70.4 +/- 3.7 mm, 34.3 +/- 3.6 mm, 48.8 +/- 4.7% respectively. Component size of medio-lateral length of 65~85 mm and lateral antero-posterior length of 30~45 mm, would be required for the Korean population. Aspect ratios were correlated to antero-posterior lengths positively (p < 0.05). CONCLUSION: No prostheses had fulfilled all the requirements for Korean knees in this study. These data could be used for design the optimal components for Korean.

The Study of Anatomical Measurement of Proximal tibia and Fitness of tibial Prosthesis in Total Knee Arthroplasty / 대한정형외과학회잡지

OBJECTIVES: The purpose of this study is to provide the basic data for anatomy of proximal tibia by real measurement, to determine the morphologic fitness between the proximal tibia of Korean and the tibial prosthesis in total knee arthroplasty, and consequently to provide basic data for development of prosthesis that appropriate to Korean. MATERIALS AND METHODS: The anteroposterior length and mediolateral length of proximal tibia were measured for 173 knees of 117 patients who underwent total knee arthroplasty. Also, obtained data from intraoperative measure of proximal tibia were analysed according to patient's age, sex and disease. RESULTS: The results show that average mediolateral length of proximal tibia is 72.7 +/- 4.0mm, average anteroposterior length of medial plateau is 48.0 +/- 3.1mm, and average anteroposterior length of lateral plateau is 39.8 +/- 2.9mm. The mediolateral length of proximal tibia and the anteroposterior length of medial tibial plateau are significantly larger than tibial prosthesis designed by 5 different companies. The morphological differences according to disease entity are significantly larger in osteoarthritic patient group than in other disease entity. The significant difference according to patient's age is not found. CONCLUSION: The results of this study show the morphologic discrepancy between the proximal tibia of Korean and the tibial prostheses, and the development of design of tibial prosthesis for Korean should be considered.