MRI of Migrated Polyethylene Insert of Mobi-C Implant

Objectives: Image Derived Instrumentation (IDI) has been introduced into regular use in modern day total knee arthroplasty (TKA) with many potential benefits touted. Despite this, much of the research involving IDI has failed to prove any significant benefit in alignment, operative time, blood loss and cost. The purpose of this study, the first of its kind, was to compare IDI with non-IDI TKA with respect to rate of revision. Methods: The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) was queried to analyse the survivorship of primary TKAs using IDI reported to the AOANJRR, between April 2009 to December 2014, compared with those without IDI instrumentation. Subgroup analysis was performed to determine the effect of polyethylene insert thickness upon IDI outcomes. The Kaplan-Meier method and proportional hazards models were used to determine the cumulative rates of revision and which prostheses or circumstances lead to an increased risk of revision. Results: In the period studied, there were 11197 primary TKAs performed utilising IDI. This was 4.8% of all primary TKAs during this period. The overall rate of revision/100 observed years was 1.07 in the PSI group, compared with, 0.82 in the standard group. This was equivalent to a hazard ratio (HR) of 1.15 (1.01,1.31; p=0.041). Posterior stabilised (PS) knees in particular showed an increased risk when compared with minimally stabilised knees when using IDI (HR=1.49; p=0.002) and non-IDI PS knees (HR=1.30; p=0.014). Subgroup analysis of the PSI (Zimmer); Signature (Vanguard) and Visionaire (Smith and Nephew) systems by polyethylene insert thickness found varied alteration in revision rates. Of the specific prosthetic combinations examined the NEXGEN CR FLEX/NEXGEN >11 mm poly (909 pts) HR 1.83 p=0.022 and GII Oxinium PS/GII <11 mm poly (868 pts) HR 1.45 p=0.049 were found to have significantly elevated risk of revision with the use of IDI. Conclusion: Using the AOANJRR we have shown that in primary TKAs, the use of IDI is associated with an increased overall revision rate. This is particularly prevalent in those knees using posterior stabilisation. The effect of polyethylene insert thickness varied dependent on manufacturer. The reasons for this cannot be determined from this analysis but suggest caution should be exercised in relation to this technology. Further study is warranted to better understand the reasons for increased revision rates.

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Enhanced patella tracking in rotating platform total knee replacements, friend or foe? A case of iliotibial band impingement by rotating polyethylene insert

Journal of Orthopaedics Trauma and Rehabilitation ◽

10.1177/2210491719859594 ◽

2019 ◽

Vol 26 (2) ◽

pp. 99-104

Author(s):

Michelle Kar Lam Li ◽

Lawrence Chun Man Lau ◽

Yuk Wah Hung ◽

Ka Bon Kwok ◽

Alexander Pak Hin Chan ◽

...

Keyword(s):

Total Knee Replacement ◽

Knee Replacement ◽

Knee Kinematics ◽

Iliotibial Band ◽

Polyethylene Insert ◽

Rotating Platform ◽

Total Knee Replacements ◽

Knee Replacements ◽

Total Knee ◽

Patella Tracking

Rotating platform total knee replacement implants have been marketed to allow more precise approximation of normal knee kinematics and enhance patella tracking. At liberty of rotation, the distinct mobile polyethylene insert design does have its pitfalls in spite of purported merits. We report a case of lateral knee pain following rotating platform total knee replacement, attributable to iliotibial band impingement by the rotating polyethylene insert. Prompt treatment via arthroscopic release circumvented a traumatic and costly revision procedure.

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Outcome of Isolated Tibial Polyethylene Insert Exchange after Total Knee Arthroplasty

The Journal of the Korean Orthopaedic Association ◽

10.4055/jkoa.2011.46.2.114 ◽

2011 ◽

Vol 46 (2) ◽

pp. 114

Author(s):

Churl Hong Chun ◽

Jeong Woo Kim ◽

Seok Hyun Kweon ◽

Byong San Choi ◽

Keun Churl Chun

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

Polyethylene Insert ◽

Total Knee

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Changes in postoperative extension angle after total knee arthroplasty: Effect of polyethylene insert thickness

Journal of Orthopaedic Science ◽

10.1016/j.jos.2018.12.013 ◽

2019 ◽

Vol 24 (4) ◽

pp. 674-679 ◽

Cited By ~ 2

Author(s):

Yuichi Kishimura ◽

Yoshio Matsui ◽

Masanori Matsuura ◽

Noriaki Hidaka

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

Polyethylene Insert ◽

Total Knee

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Periprosthetic bone response to axial loading following TKR

Multidiscipline Modeling in Materials and Structures ◽

10.1108/mmms-06-2018-0109 ◽

2019 ◽

Vol 16 (2) ◽

pp. 359-372

Author(s):

Ravishanker Baliga ◽

Sharat K. Rao ◽

Raghuvir Pai ◽

Satish B. Shenoy ◽

Atmananda K. Hegde ◽

...

Keyword(s):

Stress Shielding ◽

Axial Loading ◽

Computational Time ◽

System Response ◽

Polyethylene Insert ◽

Bone Implant ◽

Content Type ◽

Implant Material ◽

Bone Response ◽

Implant System

Purpose The purpose of this paper is to investigate by means of finite element analysis (FEA), the effect of polyethylene insert thickness and implant material, under axial loading following TKA. Design/methodology/approach The 3D geometric model of bone was processed using the CT scan data by MIMICS (3matic Inc.), package. Implant components were 3D scanned and subsequently 3D modeled using ANSYS Spaceclaim and meshed in Hypermesh (Altair Hyperworks). The assembled, meshed bone-implant model was then input to ABAQUS for FE simulations, considering axial loading. Findings Polyethylene insert thickness was found to have very little or no significance (p>0.05) on the mechanical performance, namely, stress, strain and stress shielding of bone-implant system. Implant material was found to have a very significant effect (p<0.05) on the performance parameters and greatly reduced the high stress zones up to 60 percent on the tibial flange region and periprosthetic region of tibia. Originality/value Very few FEA studies have been done considering a full bone with heterogeneous material properties, to save computational time. Moreover, four different polyethylene insert thickness with a metal-backed and all-poly tibial tray was considered as the variables affecting the bone-implant system response, under static axial loading. The authors believe that considering a full bone shall lead to more precise outcomes, in terms of the response of bone-implant system, namely, stress, strains and stress shielding in the periprosthetic region, to loading.

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