Total knee replacement wear during simulated gait with mechanical and anatomic alignments

Total knee replacements (TKR) have historically been implanted perpendicular to the mechanical axis of the knee joint, with a commensurate external rotation of the femur in flexion relative to the posterior condylar axis (PCA). Although this mechanical alignment (MA) method has typically offered good long-term survivorship of implants, it may result in alignment of the implant that departs significantly from the native Joint Line (JL) in extension and flexion for a considerable portion of the patient population. There is a growing interest with surgeons to implant TKR components more closely aligned to the natural JL (Anatomic Alignment-AA) of the patient’s knee joint to reduce the need for soft tissue releases during surgery, potentially improving knee function and patient satisfaction. Using a previously-validated finite element model of the lower extremity, implant- and alignment-specific loading conditions were developed and applied in a wear experiment via a six-degree-of-freedom joint simulator. MA was defined as 0° Joint Line (JL), 0° varus hip-knee-ankle (HKA) angle, and 3° external femoral rotation. AA was defined as 5° varus JL, 3° varus HKA, and 0° femoral rotation. The experiment returned wear rates of 3.76 ± 0.51 mg/million cycles (Mcyc) and 2.59 ± 2.11 mg/Mcyc for ATTUNE® cruciate-retaining (CR) fixed bearing (FB) in MA and AA, respectively. For ATTUNE posterior-stabilized (PS) FB in AA, the wear rate was 0.97 ± 1.11 mg/Mcyc. For ATTUNE CR rotating platform (RP), the wear rates were 0.23 ± 0.19 mg/Mcyc, 0.48 ± 1.02 mg/Mcyc in MA and AA respectively. Using a two-way ANOVA, it was determined that there was no significantly difference in the wear rates between AA and MA ( p = 0.144) nor the wear rate of ATTUNE PS FB in AA significantly different from either ATTUNE CR FB or ATTUNE CR RP.

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FEELING THE SQUEEZE: CURRENT DESIGNS OF FEMORAL ROTATION GUIDES FOR FEMORAL COMPONENT POSITIONING DURING TOTAL KNEE REPLACEMENT DO NOT MAINTAIN THE POSTERIOR JOINT LINE AND IN SOME CASES MAY RESULT IN FLEXION INSTABILITY

The Knee ◽

10.1016/j.knee.2020.07.048 ◽

2020 ◽

Vol 27 ◽

pp. S19

Author(s):

P.A. Mac Suibhne ◽

M. Ganapathi

Keyword(s):

Total Knee Replacement ◽

Femoral Component ◽

Knee Replacement ◽

Joint Line ◽

Femoral Rotation ◽

Total Knee

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Kinematic Analysis of Total Knee Arthroplasty(TKA) using Orthosensor system: Externally rotated femoral prosthesis versus Traditional design prosthesis

10.29007/95p5 ◽

2020 ◽

Author(s):

Seung-Min Na ◽

Gun-Woo Kim ◽

Nam-Hun Lee ◽

Young-Woo Chung ◽

Jongkeun Seon ◽

...

Keyword(s):

Femoral Component ◽

External Rotation ◽

Lateral Compartment ◽

Medial Compartment ◽

Femoral Rotation ◽

Femoral Prosthesis ◽

Significant Difference ◽

Total Knee ◽

Femoral Rollback ◽

Roll Back

Purpose The purpose of this study was to elucidate kinematic change according to the implant’s specific femoral rotation by using orthosensor implant with three degrees external rotation of femoral rotation rebuilt and traditional TKA implant without rebuilt of the femoral rotation .Methods Twenty-eight patients (34 knees) underwent TKA using traditional TKA implant and 16 patients (22 knees) underwent TKA using implant with three degrees external rotation of femoral rotation. Patients were followed up for at least 1 year. Mean age of patients was 71.1 years (range, 60 to 80 years) at the time of surgery. After implantation of femur and tibial components, we applied the orthosensor system, to evaluate femoral rollback of the new artificial joint. Femoral rollback was analyzed using digitized screenshot function of orthosensor system.Results Overall femoral tracking proportion regardless of implants was significantly higher on the medial compartment compared to that on the lateral compartment (13.3 ± 8.4% vs. 6.3 ± 5.0%, p < 0.001). Regarding femoral tracking according to each compartment, externally rotated femoral prosthesis and traditional prosthesis showed 12.1 ± 8.2% and 14.2 ± 8.6% (p = 0.371) on the medial compartment and 8.0 ± 5.8% and 5.2 ± 4.2% (p = 0.059) on the lateral compartment, respectively.Conclusion Our study showed reverse femoral roll-back movement with higher tracking distance on the lateral compartment during TKA. externally rotated femoral prosthesis TKA system with femoral component 3-degree rebuilt showed less roll-back difference between medial and lateral compartments compared to traditional TKA system. Fortunately, both TKA systems had excellent short-term clinical outcomes without having significant difference between the two. With longer follow-up and larger cohort, the advantage and effectiveness of femoral component rotation can be elucidated in the future.

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Optimal Design of Patient-Specific Total Knee Arthroplasty for Improvement in Wear Performance

Journal of Clinical Medicine ◽

10.3390/jcm8112023 ◽

2019 ◽

Vol 8 (11) ◽

pp. 2023 ◽

Cited By ~ 1

Author(s):

Yong-Gon Koh ◽

Kyung-Hwan Jung ◽

Hyoung-Taek Hong ◽

Kang-Min Kim ◽

Kyoung-Tak Kang

Keyword(s):

Total Knee Arthroplasty ◽

Optimal Design ◽

Knee Arthroplasty ◽

External Rotation ◽

Patient Specific ◽

Fe Modelling ◽

Wear Performance ◽

Wear Rates ◽

Tibial Insert ◽

Total Knee

Life expectancy is on the rise and, concurrently, the demand for total knee arthroplasty (TKA), which lasts a lifetime, is increasing. To meet this demand, improved TKA designs have been introduced. Recent advances in radiography and manufacturing techniques have enabled the production of patient-specific TKA. Nevertheless, concerns regarding the wear performance, which limit the lifespan of TKA, remain to be addressed. This study aims at reducing the wear in patient-specific TKA using design optimization and parametric three-dimensional (3D) finite-element (FE) modelling. The femoral component design was implemented in a patient-specific manner, whereas the tibial insert conformity remained to be determined by design variables. The gait cycle loading condition was applied, and the optimized model was validated by the results obtained from the experimental wear tests. The wear predictions were iterated for five million gait cycles using the computational model with force-controlled input. Similar patterns for internal/external rotation and anterior/posterior translation were observed in both initial and optimal models. The wear rates for initial and optimal models were recorded as 23.2 mm3/million cycles and 16.7 mm3/million cycles, respectively. Moreover, the experimental wear rate in the optimal design was 17.8 mm3/million cycles, which validated our optimization procedure. This study suggests that tibial insert conformity is an important factor in influencing the wear performance of patient-specific TKA, and it is capable of providing improved clinical results through enhanced design selections. This finding can boost the future development of patient-specific TKA, and it can be extended to other joint-replacement designs. However, further research is required to explore the potential clinical benefits of the improved wear performance demonstrated in this study.

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Comparison of Kinematics in Cruciate Retaining and Posterior Stabilized for Fixed and Rotating Platform Mobile-Bearing Total Knee Arthroplasty with respect to Different Posterior Tibial Slope

BioMed Research International ◽

10.1155/2018/5139074 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 4

Author(s):

Kyoung-Tak Kang ◽

Yong-Gon Koh ◽

Juhyun Son ◽

Oh-Ryong Kwon ◽

Jun-Sang Lee ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

External Rotation ◽

Mobile Bearing ◽

Tibial Slope ◽

Posterior Stabilized ◽

Rotating Platform ◽

Cruciate Retaining ◽

Posterior Tibial ◽

Total Knee

Reconstructed posterior tibial slope (PTS) plays a significant role in kinematics restoration after total knee arthroplasty (TKA). However, the effect of increased and decreased PTS on prosthetic type and design has not yet been investigated. We used a finite element model, validated using in vitro data, to evaluate the effect of PTS on knee kinematics in cruciate-retaining (CR) and posterior-stabilized (PS) fixed TKA and rotating platform mobile-bearing TKA. Anterior-posterior tibial translation and internal-external tibial rotation were investigated for PTS ranging from -3° to 15°, with increments of 1°, for three different designs of TKA. Tibial posterior translation and external rotation increased as the PTS increased in both CR and PS TKAs. In addition, there was no remarkable difference in external rotation between CR and PS TKAs. However, for the mobile-bearing TKA, PTS had less effect on the kinematics. Based on our computational simulation, PTS is the critical factor that influences kinematics in TKA, especially in the CR TKA. Therefore, the surgeon should be careful in choosing the PTS in CR TKAs.

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A Finite Element Model of a Rotating Platform Total Knee Employing a Nonlinear, Dual-Surface-Contact Formulation

10.1115/imece2000-2582 ◽

2000 ◽

Author(s):

Jason K. Otto ◽

Thomas D. Brown ◽

John J. Callaghan

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Mobile Bearing ◽

Element Model ◽

Polyethylene Insert ◽

Rotating Platform ◽

Mobile Interface ◽

Surface Contact ◽

Total Knee

Abstract Mobile bearing total knees avoid the conformity/constraint tradeoff of fixed bearing total knees. However, a recent in vivo fluoroscopic study of the most popular mobile bearing total knee in the U.S. showed that bearing motion failed to occur in half of the patients observed. A nonlinear, multiple-surface contact finite element model of a rotating platform total knee was therefore developed to investigate the interaction at the “mobile” interface (contact between the tibial tray and the polyethylene insert) under physiologically relevant loads (1–4 BW) and rotations (10° endorotation). The data showed that there was a linear relationship between axial load and the torque resisting endorotation. Peak contact stresses were located on the medial and lateral peripheral edges of the polyethylene insert. All relative rotation occurred at the “mobile” interface. The same trends were seen in a complementary experimental study of the same components, suggesting that the finite element model is valid under these loading conditions.

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What factors drive polyethylene wear in total knee arthroplasty?

The Bone & Joint Journal ◽

10.1302/0301-620x.103b11.bjj-2020-2334.r1 ◽

2021 ◽

Vol 103-B (11) ◽

pp. 1695-1701

Author(s):

John H. Currier ◽

Barbara H. Currier ◽

Matthew P. Abdel ◽

Daniel J. Berry ◽

Alexander J. Titus ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Wear Rate ◽

Knee Arthroplasty ◽

Patient Specific ◽

Wear Performance ◽

Thickness Change ◽

Wear Rates ◽

Tibial Insert ◽

Total Knee

Aims Wear of the polyethylene (PE) tibial insert of total knee arthroplasty (TKA) increases the risk of revision surgery with a significant cost burden on the healthcare system. This study quantifies wear performance of tibial inserts in a large and diverse series of retrieved TKAs to evaluate the effect of factors related to the patient, knee design, and bearing material on tibial insert wear performance. Methods An institutional review board-approved retrieval archive was surveyed for modular PE tibial inserts over a range of in vivo duration (mean 58 months (0 to 290)). Five knee designs, totalling 1,585 devices, were studied. Insert wear was estimated from measured thickness change using a previously published method. Linear regression statistical analyses were used to test association of 12 patient and implant design variables with calculated wear rate. Results Five patient-specific variables and seven implant-specific variables were evaluated for significant association with lower insert wear rate. Six were significant when controlling for other factors: greater patient age, female sex, shorter duration in vivo, polished tray, highly cross-linked PE (HXLPE), and constrained knee design. Conclusion This study confirmed that knee wear rate increased with duration in vivo. Older patients and females had significantly lower wear rates. Polished modular tibial tray surfaces, HXLPE, and constrained TKA designs were device design factors associated with significantly reduced wear rate. Cite this article: Bone Joint J 2021;103-B(11):1695–1701.

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The influence of total knee arthroplasty design on kneeling kinematics: a prospective randomized clinical trial

The Bone & Joint Journal ◽

10.1302/0301-620x.103b1.bjj-2020-0958.r1 ◽

2021 ◽

Vol 103-B (1) ◽

pp. 105-112 ◽

Cited By ~ 1

Author(s):

Joseph T. Lynch ◽

Diana M. Perriman ◽

Jennie M. Scarvell ◽

Mark R. Pickering ◽

Catherine R. Galvin ◽

...

Keyword(s):

Clinical Trial ◽

Total Knee Arthroplasty ◽

Randomized Clinical Trial ◽

Knee Arthroplasty ◽

External Rotation ◽

Rotating Platform ◽

Single Plane ◽

Prospective Randomized Clinical Trial ◽

High Flexion ◽

Total Knee

Aims Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs. Methods In total, 68 patients were randomized to either a posterior stabilized (PS-FB), cruciate-retaining (CR-FB), or rotating platform (CR-RP) design. Of these patients, 64 completed a minimum one year follow-up. Patients completed full-flexion kneeling while being imaged using single-plane fluoroscopy. Kinematics were calculated by registering the 3D implant models onto 2D-dynamic fluoroscopic images and exported for analysis. Results CR-FB designs had significantly lower maximal flexion (mean 116° (SD 2.1°)) compared to CR-RP (123° (SD 1.6°)) and PS-FB (125° (SD 2.1°)). The PS-FB design displayed a more posteriorly positioned femur throughout flexion. Furthermore, the CR-RP femur was more externally rotated throughout kneeling. Finally, individual patient kinematics showed high degrees of variability within all designs. Conclusion The increased maximal flexion found in the PS-FB and CR-RP designs were likely achieved in different ways. The PS-FB design uses a cam-post to hold the femur more posteriorly preventing posterior impingement. The external rotation within the CR-RP design was surprising and hasn’t previously been reported. It is likely due to the polyethylene bearing being decoupled from flexion. The findings of this study provide insights into the function of different knee arthroplasty designs in the context during deep kneeling and provide clinicians with a more kinematically informed choice for implant selection and may allow improved management of patients' functional expectations. Cite this article: Bone Joint J 2021;103-B(1):105–112.

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Changes of ankle inclinations after total knee arthroplasty

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967117s00102 ◽

2017 ◽

Vol 5 (2_suppl2) ◽

pp. 2325967117S0010

Author(s):

Murat Celal Sözbilen ◽

Elcil Kaya Biçer ◽

Semih Aydoğdu ◽

Hakkı Sur

Keyword(s):

Total Knee Arthroplasty ◽

Knee Joint ◽

Ankle Joint ◽

Knee Arthroplasty ◽

Joint Line ◽

X Rays ◽

Group I ◽

Total Knee ◽

Group Ii ◽

Line Inclination

Aim: To evaluate the changes in ankle joint line inclination in patients who had total knee arthroplasty due to degenerative osteoarthritis. Material/Method: Sixty-two knees (with a mean age of 71,66±6,78 years, follow-up 52,34±27,42 months) which had undergone total knee arthroplasty between November 1996 and May 2014 were included in this retrospective study. The knee joint line orientations (KJLO) of the prosthesis and ankle joint line inclination (AJLI) relative to the floor were evaluated on postoperative standard standing long-leg X-rays. The AJLI relative to the floor was defined as the angle between the tangent to the subchondral plate of the talus and the horizontal grid line on radiographs. In order to determine the effects of KJLO and high varus on AJLI, patients were divided into two each groups that were pre-operative mechanical axes (MA) as <20° (n=35, group1) and >=20° (n=27, group2) and post-operative MA <3° (n=32, group a) and >=3° (n=30, group b). In addition, the changes in AJLI were compared between each group. The patients were regrouped as either <=3° (n=28, group i) or >3° (n=34, group ii), in terms of the postoperative KJLO. Inclination angles of the prosthesis were compared between each groups. Statistical analysis was performed with SPSS v18. Results: Mean MA of pre-operative and post-operative were 16,35±6,56° and 3,92±3,35°, respectively. All ankle inclinations were lateralized. AJLI, were significantly decreased from pre-operative mean 7,37°±3,19° to post-operative mean 3,71°±2,22° (p<0,0001). The mean of change was 3,65°±3,03°. However, pre-operative AJLIs were significantly increased in high varus group (group1: 6,34°±2,54°, group2: 8,70°±3,48°, p=0,003); post-operative AJLIs did not differ significantly (group1: 3,55°±2,36°, group2: 3,92°±2,05°, p=0,516) with respect to the MA. The changes in preop-postop AJLI’s were significantly higher in high varus group again (p=0,009). When the KJLO groups were compared, pre-operative AJLIs were significantly different (group i: 6,25°±2,33°, group ii: 8,29°±3,53°, p=0,004) while post-operative AJLIs did not differ significantly (group i: 3,46°±2,38°, group ii: 3,92°±2,08°, p=0,489). Conclusion: Pre-operatively high varus knees also had high ankle varus, hence ankle deformity was corrected by the restoration of the optimal lower limb aligment. Obtaining parallel orientation of the components relative to the ground, restored the AJLI. Pre-operative planning and convenient implantation of the components lead to achieve optimum knee orientation which restored the ankle joint line orientation independent from mechanical axes. Not only the goal of optimum mechanical axes but also optimum knee joint line orientation’s importance was demonsrated.

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