In Vitro Study of Backside Wear Mechanisms on Mobile Knee-Bearing Components

2005 ◽  
Vol 128 (2) ◽  
pp. 275-281 ◽  
Author(s):  
S. A. Atwood ◽  
F. E. Kennedy ◽  
J. H. Currier ◽  
D. W. Van Citters ◽  
J. P. Collier
Keyword(s):  
In Vitro Study ◽  
Mobile Bearing ◽  
Porous Coating ◽  
Third Body ◽  
Rotating Platform ◽  
Wear Performance ◽  
Tibial Tray ◽  
Inferior Surface ◽  
Pmma Bone Cement

The long-term success of a total knee replacement depends on the wear performance of a polyethylene bearing that separates a metal femoral component from a metal tibial tray. Although fixed bearing designs secure the polyethylene bearing to the tibial tray, mobile bearing knees allow the polyethylene to move relative to the tibial tray. This study has evaluated the wear performance of an intended articulation on the inferior surface of the LCS®-Rotating Platform mobile bearing by conducting clinically relevant tribological testing and comparing results to retrieved knee bearings. A retrieval analysis leads to the conclusion that third-body particles in the contact produce curvilinear scratches longer than the expected rotation of the knee on both the polyethylene bearing and the CoCr tibial tray. Tribological testing shows that polymethylmethacrylate (PMMA) bone cement particles produce worn surfaces most similar to retrievals. Porous-coating beads and bone debris also have the ability to damage both surfaces. Worn polyethylene surfaces from pin-on-flat tests show scratches longer than the excursion length, and “skipping marks”—pits spaced at smaller rotation intervals along a scratch—as observed in retrievals. These wear features suggest that a ratcheting mechanism, which moves the third-body particles further along the scratch with each cycle, may be responsible for the observed wear.

In-Vitro Study of Backside Wear Mechanism on Mobile Knee Bearing Components

2005 ◽  
Author(s):  
Sara A. Atwood ◽  
Francis E. Kennedy ◽  
John H. Currier ◽  
Douglas W. Van Citters ◽  
John P. Collier
Keyword(s):  
Bone Cement ◽  
In Vitro Study ◽  
Mobile Bearing ◽  
Fixation Method ◽  
Porous Coating ◽  
Third Body ◽  
Rotating Platform ◽  
Backside Wear

Backside wear in the form of scratching and pitting observed on a series of mobile bearing rotating platform knee retrievals (n = 100) appears to be indicative of third body wear. The appearance of scratching and pitting on the backside does not correlate with duration in vivo or with linear backside wear measurements, but there is a weak correlation with fixation method indicating that some of the third body debris may be bone cement. Tribological tests representing rotation and fretting in the knee were run with bone cement, bone chips, and metal porous coating beads placed as third bodies in the contact. Results with bone cement show scratches similar to those found on retrievals.

Quantification of third body damage to the tibial counterface in mobile bearing knees

2001 ◽  
Vol 215 (2) ◽  
pp. 171-179 ◽  
Author(s):  
V C Jones ◽  
I R Williams ◽  
D D Auger ◽  
W Walsh ◽  
D C Barton ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Mobile Bearing ◽  
In Vitro Tests ◽  
Constrained Motion ◽  
Third Body ◽  
Rotating Platform ◽  
Control Measurement ◽  
Uhmwpe Wear ◽  
Wear Damage

Fourteen pairs of explanted low contact stress (LCS) tibial interface components: six rotating platform (RP), six meniscal (MN) and two anterior-posterior (AP) glide designs, have been analysed with particular attention paid to the condition of the tibial counterfaces. The average surface roughness, Ra, for the tibial trays ranged from 0.01 to 0.087 μm, significantly greater than the unworn control measurement of 0.008 μm. The scratch geometry analysis showed that the scratch peaks were found to be consistently of a lower aspect ratio than the scratch valleys and under 1 μm in height (average asperity height - Rp = 0.52 μm, aspect ratio Δ p = 0.01, average asperity depth Rv = 1.10 μm, Δ v = 0.05). The largest scratches were 3-4 μm in both Rp and Rv In vitro tests have shown that ultra-high molecular weight polyethylene (UHMWPE) wear increases in the presence of counterface scratches perpendicular to the direction of motion. In these explants, the unidirectional motion produced scratches parallel to the direction of sliding which is predicted to produce a smaller increase in UHMWPE wear. Other designs in mobile bearing knees have less constrained motion at the tibial counterface and this has been shown to accelerate wear; it may also lead to a further increase in wear in the presence of third body scratches. It may be possible in future knee designs to reduce this type of wear damage by introducing alternative materials or coatings which are more resistant to scratching and surface roughening.

Kinematics of mobile-bearing unicompartmental knee arthroplasty compared to native: results from an in vitro study

2017 ◽  
Vol 137 (11) ◽  
pp. 1557-1563 ◽  
Author(s):  
Geert Peersman ◽  
Josh Slane ◽  
Philippe Vuylsteke ◽  
Susanne Fuchs-Winkelmann ◽  
Philipp Dworschak ◽  
...  
Keyword(s):  
Knee Arthroplasty ◽  
Unicompartmental Knee Arthroplasty ◽  
In Vitro Study ◽  
Mobile Bearing ◽  
Vitro Study ◽  
Unicompartmental Knee

Equivalent wear performance of dual mobility bearing compared with standard bearing in total hip arthroplasty: in vitro study

2016 ◽  
Vol 41 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Gaël Gaudin ◽  
André Ferreira ◽  
Romain Gaillard ◽  
Jean Louis Prudhon ◽  
Jacques H. Caton ◽  
...  
Keyword(s):  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
In Vitro Study ◽  
Vitro Study ◽  
Wear Performance ◽  
Dual Mobility ◽  
Total Hip

scholarly journals <i>Pseudomonas aeruginosa</i> biofilm killing beyond the spacer by antibiotic-loaded calcium sulfate beads: an in vitro study

2021 ◽  
Vol 6 (5) ◽  
pp. 119-129
Author(s):  
Jacob R. Brooks ◽  
Devendra H. Dusane ◽  
Kelly Moore ◽  
Tripti Gupta ◽  
Craig Delury ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bone Cement ◽  
Calcium Sulfate ◽  
Joint Infection ◽  
Agar Plate ◽  
In Vitro Study ◽  
Cell Counts ◽  
Pmma Bone Cement ◽  
Antibiotic Coverage

Abstract. Introduction: Bacterial biofilms are an important virulence factor in chronic periprosthetic joint infection (PJI) and other orthopedic infection since they are highly tolerant to antibiotics and host immunity. Antibiotics are mixed into carriers such as bone cement and calcium sulfate bone void fillers to achieve sustained high concentrations of antibiotics required to more effectively manage biofilm infections through local release. The effect of antibiotic diffusion from antibiotic-loaded calcium sulfate beads (ALCS-B) in combination with PMMA bone cement spacers on the spread and killing of Pseudomonas aeruginosa Xen41 (PA-Xen41) biofilm was investigated using a “large agar plate” model scaled for clinical relevance. Methods: Bioluminescent PA-Xen41 biofilms grown on discs of various orthopedic materials were placed within a large agar plate containing a PMMA full-size mock “spacer” unloaded or loaded with vancomycin and tobramycin, with or without ALCS-B. The amount of biofilm spread and log reduction on discs at varying distances from the spacer was assessed by bioluminescent imaging and viable cell counts. Results: For the unloaded spacer control, PA-Xen41 spread from the biofilm to cover the entire plate. The loaded spacer generated a 3 cm zone of inhibition and significantly reduced biofilm bacteria on the discs immediately adjacent to the spacer but low or zero reductions on those further away. The combination of ALCS-B and a loaded PMMA spacer greatly reduced bacterial spread and resulted in significantly greater biofilm reductions on discs at all distances from the spacer. Discussion: The addition of ALCS-B to an antibiotic-loaded spacer mimic increased the area of antibiotic coverage and efficacy against biofilm, suggesting that a combination of these depots may provide greater physical antibiotic coverage and more effective dead space management, particularly in zones where the spread of antibiotic is limited by diffusion (zones with little or no fluid motion).

scholarly journals Laparoscopic vs Open Ultrasound of the Liver: An in vitro Study

HPB Surgery ◽  
1996 ◽  
Vol 10 (2) ◽  
pp. 87-89 ◽  
Author(s):  
P. J. Cozzi ◽  
J. L. McCall ◽  
J. O. Jorgensen ◽  
D. L. Morris
Keyword(s):  
Size Range ◽  
Hepatic Metastases ◽  
In Vitro Study ◽  
Random Order ◽  
Liver Tumours ◽  
Inferior Surface ◽  
Size Number ◽  
Correct Location ◽  
Sensitive Method

Intra-operative contact ultrasound is a sensitive method of detecting liver tumours. The aim of this study was to compare the sensitivity of open contact ultrasound (OUS) of the liver with laparoscopic contact ultrasound (LUS). Hypoechoic “lesions” were created in 5 fresh pig livers by inserting 28 grapes via small incisions in the inferior surface. The size (range 8–25 mm) and location of each grape was recorded. Scanning was undertaken in random order by two experienced independent observers with no knowledge of the size, number or position of the lesions, using an Aloka 650 series scanner and 7.5 MHz probes. The crude sensitivity with OUS was 96% and 100% respectively for the two observers, and 92% for each with LUS. One grape was interpreted as 2 seperate grapes on LUS by one observer. Absolute sensitivity (grapes identified in the correct location) was 86% and 93% respectively with OUS and 79% for each observer with LUS.LUS was almost as sensitive as OUS in this model of hepatic metastases.

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