Changes in knee shape and geometry resulting from total knee arthroplasty

2017 ◽  
Vol 232 (1) ◽  
pp. 67-79 ◽  
Author(s):  
Mohsen Akbari Shandiz ◽  
Paul Boulos ◽  
Stefan Karl Saevarsson ◽  
Heiko Ramm ◽  
Chun Kit (Jack) Fu ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Three Dimensional ◽  
Implant Design ◽  
Limiting Factor ◽  
Sample Population ◽  
Stability Range ◽  
Study Objective ◽  
Implant Selection ◽  
Total Knee

Changes in knee shape and geometry resulting from total knee arthroplasty can affect patients in numerous important ways: pain, function, stability, range of motion, and kinematics. Quantitative data concerning these changes have not been previously available, to our knowledge, yet are essential to understand individual experiences of total knee arthroplasty and thereby improve outcomes for all patients. The limiting factor has been the challenge of accurately measuring these changes. Our study objective was to develop a conceptual framework and analysis method to investigate changes in knee shape and geometry, and prospectively apply it to a sample total knee arthroplasty population. Using clinically available computed tomography and radiography imaging systems, the three-dimensional knee shape and geometry of nine patients (eight varus and one valgus) were compared before and after total knee arthroplasty. All patients had largely good outcomes after their total knee arthroplasty. Knee shape changed both visually and numerically. On average, the distal condyles were slightly higher medially and lower laterally (range: +4.5 mm to −4.4 mm), the posterior condyles extended farther out medially but not laterally (range: +1.8 to −6.4 mm), patellofemoral distance increased throughout flexion by 1.8–3.5 mm, and patellar thickness alone increased by 2.9 mm (range: 0.7–5.2 mm). External femoral rotation differed preop and postop. Joint line distance, taking cartilage into account, changed by +0.7 to −1.5 mm on average throughout flexion. Important differences in shape and geometry were seen between pre-total knee arthroplasty and post-total knee arthroplasty knees. While this is qualitatively known, this is the first study to report it quantitatively, an important precursor to identifying the reasons for the poor outcome of some patients. Using the developed protocol and visualization techniques to compare patients with good versus poor clinical outcomes could lead to changes in implant design, implant selection, component positioning, and surgical technique. Recommendations based on this sample population are provided. Intraoperative and postoperative feedback could ultimately improve patient satisfaction.

scholarly journals Biomechanical Assessment of a Patient-Specific Knee Implant Design Using Finite Element Method

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Qiguo Rong ◽  
Jianfeng Bai ◽  
Yongling Huang ◽  
Jianhao Lin
Keyword(s):  
Finite Element ◽  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Three Dimensional ◽  
Implant Design ◽  
Patient Specific ◽  
Biomechanical Behavior ◽  
Total Knee ◽  
Wear Damage ◽  
Three Dimensional Finite Element

Rheumatoid arthritis is the leading cause of disability in young adults. Total knee arthroplasty has been successfully used to restore the joint function. Due to small bone size, osteoporosis, and severe soft tissue disease, standard knee implant sometimes cannot be directly applied clinically and patient-specific designs may be a more rational choice. The purpose of this study was to evaluate the biomechanical behavior of a patient-specific knee implant. A three-dimensional finite element of total knee arthroplasty was developed. The mechanical strength and the wear damage of the articular surfaces were analyzed. The results show that there exist high risks of component fracture and wear damage; the proposed implant design should be abandoned. The presurgery analysis is helpful in avoiding the potential failure.

Low-Degree Tibial Slope Angle Prevents Component Overhang by Enlarging the Lateral Plateau Surface Area in Total Knee Arthroplasty

2020 ◽  
Author(s):  
Mehmet Emin Simsek ◽  
Mustafa Akkaya ◽  
Safa Gursoy ◽  
Özgür Kaya ◽  
Murat Bozkurt
Keyword(s):  
Total Knee Arthroplasty ◽  
Surface Area ◽  
Knee Arthroplasty ◽  
Tibial Plateau ◽  
Slope Angle ◽  
Three Dimensional ◽  
Tibial Slope ◽  
Total Knee ◽  
Lateral Plateau ◽  
Gender Groups

AbstractThis study aimed to investigate whether overhang or underhang around the tibial component that occurs during the placement of tibial baseplates was affected by different slope angles of the tibial plateau and determine the changes in the lateral and medial plateau diameters while changing the slope angle in total knee arthroplasty. Three-dimensional tibia models were reconstructed using the computed tomography scans of 120 tibial dry bones. Tibial plateau slope cuts were performed with 9, 7, 5, 3, and 0 degrees of slope angles 2-mm below the subchondral bone in the deepest point of the medial plateau. Total, lateral, and medial tibial plateau areas and overhang/underhang rates were measured at each cut level. Digital implantations of the asymmetric and symmetric tibial baseplates were made on the tibial plateau with each slope angles. Following the implantations, the slope angle that prevents overhang or underhang at the bone border and the slope angle that has more surface area was identified. A significant increase was noted in the total tibial surface area, lateral plateau surface area, and lateral anteroposterior distance, whereas the slope cut angles were changed from 9 to 0 degrees in both gender groups. It was found that the amount of posteromedial underhang and posterolateral overhang increased in both the asymmetric and symmetric tibial baseplates when the slope angle was changed from 0 to 9 degrees. Although the mediolateral diameter did not change after the proximal tibia cuts at different slope angles, the surface area and anteroposterior diameter of the lateral plateau could change, leading to increased lateral plateau area. Although prosthesis designs are highly compatible with the tibial surface area, it should be noted that the component overhangs, especially beyond the posterolateral edge, it can be prevented by changing the slope cut angle in males and females.

scholarly journals Finite-element analysis of the proximal tibial sclerotic bone and different alignment in total knee arthroplasty

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Ye-Ran Li ◽  
Yu-Hang Gao ◽  
Chen Yang ◽  
Lu Ding ◽  
Xuebo Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Tibial Plateau ◽  
Three Dimensional ◽  
Genu Varum ◽  
Sclerotic Bone ◽  
Dimensional Measurements ◽  
Tibial Cut ◽  
Total Knee

Abstract Background Despite potential for improving patient outcomes, studies using three-dimensional measurements to quantify proximal tibial sclerotic bone and its effects on prosthesis stability after total knee arthroplasty (TKA) are lacking. Therefore, this study aimed to determine: (1) the distribution range of tibial sclerotic bone in patients with severe genu varum using three-dimensional measurements, (2) the effect of the proximal tibial sclerotic bone thickness on prosthesis stability according to finite-element modelling of TKA with kinematic alignment (KA), mechanical alignment (MA), and 3° valgus alignment, and (3) the effect of short extension stem augment utilization on prosthesis stability. Methods The sclerotic bone in the medial tibial plateau of 116 patients with severe genu varum was measured and classified according to its position and thickness. Based on these cases, finite-element models were established to simulate 3 different tibial cut alignments with 4 different thicknesses of the sclerotic bone to measure the stress distribution of the tibia and tibial prosthesis, the relative micromotion beneath the stem, and the influence of the short extension stem on stability. Results The distribution range of proximal tibial sclerotic bone was at the anteromedial tibial plateau. The models were divided into four types according to the thickness of the sclerotic bone: 15 mm, 10 mm, 5 mm, and 0 mm. The relative micromotion under maximum stress was smallest after MA with no sclerotic bone (3241 μm) and largest after KA with 15 mm sclerotic bone (4467 μm). Relative micromotion was largest with KA and smallest with MA in sclerotic models with the same thickness. Relative micromotion increased as thickness of the sclerotic bone increased with KA and MA (R = 0.937, P = 0.03 and R = 0.756, P = 0.07, respectively). Relative micromotion decreased with short extension stem augment in the KA model when there was proximal tibial sclerotic bone. Conclusions The influence of proximal tibial sclerotic bone on prosthesis’s stability is significant, especially with KA tibial cut. Tibial component’s short extension stem augment can improve stability.

Implant design influences patient outcome after total knee arthroplasty

2015 ◽  
Vol 97-B (1) ◽  
pp. 64-70 ◽  
Author(s):  
D. F. Hamilton ◽  
R. Burnett ◽  
J. T. Patton ◽  
C. R. Howie ◽  
M. Moran ◽  
...  
Keyword(s):  
Patient Outcome ◽  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Implant Design ◽  
Total Knee

All-Polyethylene versus Metal-Backed Tibial Components in Total Knee Arthroplasty

2019 ◽  
Vol 32 (08) ◽  
pp. 714-718 ◽  
Author(s):  
Samuel AbuMoussa ◽  
Charles Cody White ◽  
Josef K. Eichinger ◽  
Richard J. Friedman
Keyword(s):  
Total Knee Arthroplasty ◽  
Patient Outcomes ◽  
Knee Arthroplasty ◽  
Gold Standard ◽  
Implant Design ◽  
Economic Strain ◽  
The Past ◽  
Backside Wear ◽  
Total Knee ◽  
Dynamic Shift

AbstractAll-polyethylene tibial (APT) implants were incorporated into the initial design of the first total knee arthroplasty (TKA) systems. Since then, a dynamic shift has taken place and metal-backed tibial (MBT) implants have become the gold standard in TKA. This has mostly been due to the theoretical advantages of intraoperative flexibility and improved biomechanics in addition to the heavy influence of device manufacturers. MBT implant comes not only with a higher cost but also with potential for complications such as osteolysis, backside wear, and thinning of the polyethylene insert, which were not previously seen with APT implant. The majority of studies comparing APT and MBT implants have shown no difference in clinical outcomes and survivorship. Newer studies from the past decade have begun highlighting the economic advantages of APT implant, especially in patients undergoing primary, uncomplicated TKA. Use of APT implants in younger patients and those with a body mass index > 35 has not been extensively studied, but the existing literature suggests the use of APT implant in these cohorts to be equally as acceptable. With modern implant design and instrumentation, rising utilization of TKA along with current and future economic strain on health care, the increased use of APT implant could result in massive savings without sacrificing positive patient outcomes.

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