scholarly journals Polyethylene Bearing Wear in the Oxford Unicompartmental Knee

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Priyanka Ghosh ◽  
Hasan Mohammad ◽  
Stephen Mellon ◽  
David Murray
Keyword(s):  
Wear Rate ◽  
Polyethylene Wear ◽  
Oxford Knee Score ◽  
Knee Kinematics ◽  
Mobile Bearing ◽  
Unicompartmental Knee Replacement ◽  
Late Time ◽  
Unicompartmental Knee ◽  
Implant Size ◽  
Over Time

Background and Hypothesis: The Oxford Knee is a unicompartmental knee replacement (UKR) for patients with end-stage knee osteoarthritis (OA). It contains a polyethylene (PE) mobile bearing between the femoral and tibial components that helps maintain normal knee kinematics. Unfortunately bearing wear is one of the leading causes of UKR failure. In this study, we sought to investigate PE wear rate over time and the initial deformation (creep) in early months. Project Methods: This study used radiostereometric analysis (RSA) to precisely track polyethylene bearing thickness over time in 40 medial Oxford UKR patients. The patients underwent stereo radiographs at 1 week post-op (reference), 3 months, 6 months, 1 year, 2 years, and 5 years. Model-based RSA software was used to determine the exact position of the femoral and tibial components, and Matlab was used to calculate the minimum linear distance between these two components, taken as bearing thickness. Results: The average wear rate was 0.32mm/yr (SD 0.42) in the first 3 months, 0.16mm/yr (SD 0.55) from 3 to 6 months, and 0.07mm/yr (SD 0.03) between 1 and 5 years. No correlation was found between wear rate and BMI, fixation, implant size, or 5 year Oxford Knee Score. Conclusion and Potential Impact: This was the first study to investigate detailed early and late time points of polyethylene wear in the Oxford UKR. Mean bearing wear was higher in the first 6 months, presumably due to creep, and significantly reduced from 1 year onwards, presumably while true wear took place.

scholarly journals Low polyethylene creep and wear following mobile-bearing unicompartmental knee replacement

2020 ◽  
Author(s):  
Priyanka Ghosh ◽  
Hasan R. Mohammad ◽  
Benjamin Martin ◽  
Stefano Campi ◽  
David W. Murray ◽  
...  
Keyword(s):  
Wear Rate ◽  
Knee Replacement ◽  
Oxford Knee Score ◽  
Mobile Bearing ◽  
Unicompartmental Knee Replacement ◽  
Level Of Evidence ◽  
Randomised Study ◽  
Component Size ◽  
Unicompartmental Knee ◽  
Tegner Score

Abstract Purpose The Oxford unicompartmental knee replacement (UKR) has a fully congruent mobile bearing to minimise wear. However, with younger higher demand patients, wear remains a concern. The aim of this study was to quantify the wear rate of Phase 3 Oxford UKR bearings over the course of 5 years and to identify the factors that influence it. Methods 40 medial Oxford UKRs recruited for a randomised study of cemented and cementless fixation were studied with Radiostereometric analysis (RSA) at 1 week, 3 months, 6 months, 1 year, 2 years, and 5 years post-operatively and bearing thickness was calculated. Penetration, defined as the change in thickness compared to the 1-week measurement, was determined. Creep (early penetration) and wear (late penetration at a constant rate) were calculated. The influence of demographic factors, Oxford Knee Score (OKS), Tegner score, fixation and bearing overhang (determined by RSA) on wear was analysed. Results After 6 months the penetration rate was constant, indicating that wear alone was occurring. The wear rate was 0.07 mm/year (SD 0.03). The creep was 0.06 mm with about 95% occurring during the first 3 months. There was no significant relationship between fixation (cemented/cementless), age, component size, OKS and Tegner score with wear rate. Increasing BMI was associated with decreasing wear (p = 0.042). 37/40 bearings overhung the tibia to some extent and 23/40 overhung the tibia medially. An increase in the area of overhang (p = 0.036), amount of medial overhang (p = 0.028) and distance between the bearing and tibial wall (p = 0.019) were associated with increased wear. Bearings that did not overhang (0.06 mm/year) had less wear (p = 0.025) than those that did (0.08 mm/year). There was no relationship (p = 0.6) between the femoral contact area and wear. Conclusion During the first three to six months after implantation, the bearing becomes 0.06 mm thinner due to creep. The combined wear rate of the upper and lower surfaces of the bearing is constant (0.07 mm/year). The wear is lower if the bearing does not overhang the tibia so surgeons should aim for the bearing to be close to the tibial wall. The orientation of the femoral component does not influence wear. Level of evidence Retrospective Study, Level III.

Polyethylene wear of mobile-bearing unicompartmental knee replacement at 20 years

2011 ◽  
Vol 93-B (4) ◽  
pp. 470-475 ◽  
Author(s):  
B. J. L. Kendrick ◽  
D. J. Simpson ◽  
B. L. Kaptein ◽  
E. R. Valstar ◽  
H. S. Gill ◽  
...  
Keyword(s):  
Knee Replacement ◽  
Polyethylene Wear ◽  
Mobile Bearing ◽  
Unicompartmental Knee Replacement ◽  
Unicompartmental Knee

scholarly journals Computational wear prediction of insert conformity and material on mobile-bearing unicompartmental knee arthroplasty

2019 ◽  
Vol 8 (11) ◽  
pp. 563-569 ◽  
Author(s):  
Yong-Gon Koh ◽  
Jin-Ah Lee ◽  
Hwa-Yong Lee ◽  
Hyo-Jeong Kim ◽  
Kyoung-Tak Kang
Keyword(s):  
Wear Rate ◽  
Contact Pressure ◽  
Knee Arthroplasty ◽  
Contact Area ◽  
Unicompartmental Knee Arthroplasty ◽  
Polyethylene Wear ◽  
Mobile Bearing ◽  
Volumetric Wear ◽  
Wear Performance ◽  
Unicompartmental Knee

Objectives Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty with isolated medial or lateral compartment osteoarthritis. However, polyethylene wear can significantly reduce the lifespan of UKA. Different bearing designs and materials for UKA have been developed to change the rate of polyethylene wear. Therefore, the objective of this study is to investigate the effect of insert conformity and material on the predicted wear in mobile-bearing UKA using a previously developed computational wear method. Methods Two different designs were tested with the same femoral component under identical kinematic input: anatomy mimetic design (AMD) and conforming design inserts with different conformity levels. The insert materials were standard or crosslinked ultra-high-molecular-weight polyethylene (UHMWPE). We evaluated the contact pressure, contact area, wear rate, wear depth, and volumetric wear under gait cycle loading conditions. Results Conforming design inserts had the lower contact pressure and larger contact area. However, they also had the higher wear rate and volumetric wear. The improved wear performance was found with AMD inserts. In addition, the computationally predicted volumetric wear of crosslinked UHMWPE inserts was less than half that of standard UHMWPE inserts. Conclusion Our results showed that increasing conformity may not be the sole predictor of wear performance; highly crosslinked mobile-bearing polyethylene inserts can also provide improvement in wear performance. These results provide improvements in design and materials to reduce wear in mobile-bearing UKA. Cite this article: Bone Joint Res 2019;8:563–569.

Comparison of articular and backside polyethylene wear in mobile bearing unicompartmental knee replacement

The Knee ◽  
2017 ◽  
Vol 24 (2) ◽  
pp. 429-433 ◽  
Author(s):  
Matthew G. Teeter ◽  
James L. Howard ◽  
Richard W. McCalden ◽  
Douglas D. Naudie
Keyword(s):  
Knee Replacement ◽  
Polyethylene Wear ◽  
Mobile Bearing ◽  
Unicompartmental Knee Replacement ◽  
Unicompartmental Knee

scholarly journals An Unusual Presentation of Insert Dislocation and MCL Rupture in Unicompartmental Knee Replacement with 2 Years Postoperative Results: Does It Functional?

2019 ◽  
Vol 2019 ◽  
pp. 1-5 ◽  
Author(s):  
Ali Asma ◽  
Mehmet Erduran ◽  
Musa Eymir
Keyword(s):  
Quality Of Life ◽  
Pain Intensity ◽  
Knee Replacement ◽  
Functional Capacity ◽  
Primary Repair ◽  
Mobile Bearing ◽  
Unicompartmental Knee Replacement ◽  
Unicompartmental Knee ◽  
Bearing Dislocation

According to our knowledge, there is no prior article that reports functional results of medial collateral ligament (MCL) primary repair and insert change after MCL rupture and mobile-bearing dislocation as a late complication of unicompartmental knee replacement (UKR). Firstly, 63-year-old woman was treated with UKR due to anteromedial knee osteoarthritis of the right knee joint. 1 year after UKR surgery, she suffered from MCL rupture and mobile-bearing dislocation because of falls while getting on a public bus, and therefore, secondly, she was operated with MCL primary repair and mobile-bearing change and followed up for 2 years. The patient was evaluated regarding functional capacity, pain intensity, range of motion (RoM), and quality of life. Our case showed an improvement in the functional level and the other outcomes (pain intensity and quality of life) at postoperative 2nd year when compared to the preoperative period. The wellbeing of our case in about the postop 2nd year functional capacity and also other outcomes after revision surgery prompted us to continue to this surgery approach in the surgical management of similar cases that may arise thereafter.

scholarly journals Polyethylene wear in Oxford unicompartmental knee replacement

2010 ◽  
Vol 92-B (3) ◽  
pp. 367-373 ◽  
Author(s):  
B. J. L. Kendrick ◽  
D. Longino ◽  
H. Pandit ◽  
U. Svard ◽  
H. S. Gill ◽  
...  
Keyword(s):  
Knee Replacement ◽  
Polyethylene Wear ◽  
Unicompartmental Knee Replacement ◽  
Unicompartmental Knee

Can Normal Knee Kinematics Be Restored with Unicompartmental Knee Replacement?

2005 ◽  
Vol 87 (2) ◽  
pp. 332-338 ◽  
Author(s):  
Shantanu Patil ◽  
Clifford W. Colwell ◽  
Kace A. Ezzet ◽  
Darryl D. DʼLima
Keyword(s):  
Knee Replacement ◽  
Knee Kinematics ◽  
Unicompartmental Knee Replacement ◽  
Normal Knee ◽  
Unicompartmental Knee

Early failure of a mobile-bearing unicompartmental knee replacement

2009 ◽  
Vol 17 (10) ◽  
pp. 1178-1183 ◽  
Author(s):  
Mateen H. Arastu ◽  
J. Vijayaraghavan ◽  
H. Chissell ◽  
J. B. Hull ◽  
J. H. Newman ◽  
...  
Keyword(s):  
Knee Replacement ◽  
Mobile Bearing ◽  
Unicompartmental Knee Replacement ◽  
Early Failure ◽  
Unicompartmental Knee

Mobile-bearing lateral unicompartmental knee replacement with the Oxford domed tibial component

2012 ◽  
Vol 94-B (10) ◽  
pp. 1356-1361 ◽  
Author(s):  
M. R. Streit ◽  
T. Walker ◽  
T. Bruckner ◽  
C. Merle ◽  
J. P. Kretzer ◽  
...  
Keyword(s):  
Knee Replacement ◽  
Tibial Component ◽  
Mobile Bearing ◽  
Unicompartmental Knee Replacement ◽  
Unicompartmental Knee
Sign in / Sign up

Export Citation Format

Share Document