Clinical Wear Measurement on Low Contact Stress Rotating Platform Knee Bearings

Atwood, Sara A.; Currier, John H.; Mayor, Michael B.; Collier, John; Citters, Douglas W. Van; Kennedy, Francis E.

doi:10.1016/j.arth.2007.06.005

Cited by 55 publications

(31 citation statements)

References 19 publications

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“…Furthermore, the amount and severity of wear damage on the mobile-bearing surface are comparable to those measured using similar regional wear damage scoring on fixed-bearing tibiofemoral surfaces (Table 1), suggesting this second bearing surface adds to rather than reduces the wear damage in these implants. Our observations confirm those of the other investigators who recently examined retrieved mobile-bearing implants [1,5,7,10,11]. These authors also reported burnishing and third-body debris as major causes of wear damage to mobile-bearing polyethylene components.…”

Section: Discussionsupporting

confidence: 91%

Wear Damage in Mobile-bearing TKA is as Severe as That in Fixed-bearing TKA

Kelly

Wright

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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Background Mobile-bearing TKAs reportedly have no clinical superiority over fixed-bearing TKAs, but a potential benefit is improved polyethylene wear behavior. Questions/purposes We asked whether extent of damage and wear patterns would be less severe on retrieved mobile-bearing TKAs than on fixed-bearing TKAs and if correlations with patient demographics could explain differences in extent or locations of damage. Methods We performed damage grading and mapping of 48 mobile-bearing TKAs retrieved due to osteolysis/loosening, infection, stiffness, instability or malpositioning. Visual grading used stereomicroscopy to identify damage, and a grade was assigned based on extent and severity. Each damage mode was then mapped onto a photograph of the implant surface, and the area affected was calculated. Results Marked wear damage occurred on both surfaces, with burnishing, scratching, and pitting the dominant modes. Damage occurred over a large portion of both surfaces, exceeding the available articular borders in nearly 30% of implants. Wear of mobile-bearing surfaces included marked third-body debris. Damage on tibiofemoral and mobile-bearing surfaces was not correlated with patient BMI or component alignment. Damage on mobilebearing surfaces was positively correlated with length of implantation and was greater in implants removed for osteolysis or instability than in those removed for stiffness or infection. Conclusions Each bearing surface in mobile-bearing implants was damaged to an extent similar to that in fixedbearing implants, making the combined damage score higher than that for fixed-bearing implants. Mobile-bearing TKAs did not improve wear damage, providing another argument against the superiority of these implants over fixed-bearing implants.

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Section: Discussionsupporting

confidence: 91%

Wear Damage in Mobile-bearing TKA is as Severe as That in Fixed-bearing TKA

Kelly

Wright

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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“…Lesser contributors to the variation are multiple surgeons and different surgical techniques for fixed-bearing and rotating-platform knees. We did our best to control for these variables (Table 1) but like other studies that evaluate revision retrievals, we could not control all variables [1,2,9,14,15]. Although this study only used one manufacturer, there were three designs evaluated.…”

Section: Discussionmentioning

confidence: 99%

“…Unfortunately, volumetric analysis of retrieved tibial polyethylene components is rarely performed. When threedimensional retrieval analysis is performed, it has been limited in the ability to separate wear from penetration because the volumetric calculation is typically based on shapes generated from multiple penetration measurements [1,2,9,14,15].…”

Section: Introductionmentioning

confidence: 99%

Can Microcomputed Tomography Measure Retrieved Polyethylene Wear? Comparing Fixed-bearing and Rotating-platform Knees

Engh

Zimmerman

Hopper

et al. 2013

Clinical Orthopaedics &Amp; Related Research

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Background Wear of total knee polyethylene has been quantified gravimetrically with thickness measurements and evaluation of surface wear modes. However, these techniques do not localize volumetric wear. Questions/Purposes We used micro-CT scans of retrieved total knee liners and unworn, new liners to determine the volume and location of wear. Methods We retrieved 12 fixed and 12 rotating-platform bearings after a mean 52 months of use. Inserts were weighed and thickness was measured. Micro-CT scans of retrieved and matched new liners were superimposed to compare the location and magnitude of wear. Results The average total wear was 254 ± 248 mm 3 . The average wear rate was 58 ± 41 mm 3 /year. Wear was 69% of penetration, demonstrating the contribution of deformation to knee wear. Rotating-platform wear rate was 43 ± 25 mm 3 /year and the fixed-bearing rate was 74 ± 49 mm 3 /year. Five percent of the rotating-platform wear rate came from the backside compared with 14% of the fixed-bearing wear rate. Conclusions Micro-CT can determine the volume and location of wear of retrieved tibial liners. Because the magnitude of the manufacturing tolerances was approximately half the magnitude of the total wear on average, accounting for the potential influence of tolerances is important to accurately measure volumetric wear if the unworn (preimplantation) geometry of the insert is unknown. Without accounting for tolerances, this technique may not be applicable for retrievals with a short followup that have low wear. However, application of micro-CT could be of value in determining the exact location of wear in knee simulator studies in which the same insert is measured repeatedly and manufacturing tolerances are not a concern.

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“…In simulations of the loading pressure on polyethylene inlays a significant pressure reduction in using highly conformal mobile inlays compared to "fixed bearing" systems could be achieved [8,9]. Laboratory studies have shown that significantly less abrasion of the polyethylene could be detected in rotating platform inlays [10]. But rotating platform prostheses show no superior results when compared to fixed bearing prostheses in the Hospital for Special Surgery (HSS) scores [11].…”

Section: Discussionmentioning

confidence: 99%

Rotational laxity and collateral ligament laxity following total knee arthroplasty with rotating platform

Mayr

Reinhold²,

Hube³

et al. 2014

International Orthopaedics (SICOT)

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Purpose The aim of this study was to evaluate laxity in knees with pre-operative (preop) valgus alignment compared to knees with pre-operative varus alignment after total knee arthroplasty (TKA). Methods This was a retrospective study including 81 patients, with six years follow-up, for pre-operative valgus-or varus alignment of the leg. All patients had been supplied with the same cruciate retaining (CR) TKA with rotating platform. Clinical findings were assessed by KSS, OKS and IKDC 2000 score. Rotational knee laxity was evaluated by a validated instrument (Laxitester®) with 2 Nm torque in 30°flex-ion. Collateral ligament laxity was tested manually in 30°f lexion with a bending moment of approximately5 Nm. Biomechanical results were compared to the contralateral side. Results Thirty-one patients had a preop valgus alignment of 8.96°and 50 patients a varus leg axis of 4.99°in the mean. In the preop valgus knees rotational analysis showed an increased laxity of 10.7°compared to preop varus knees (p=0.001). There was no significant difference in medial (valgus 2.6 mm, varus 2.5 mm) and lateral (valgus 2.8 mm, varus 2.7 mm) laxity. KSS and OKS showed no significant differences in the follow-up results. In the IKDC 2000 objective score 50 % of the preop varus knees and 25.8 % of the preop valgus knees were classified as nearly normal. The difference in the IKDC objective was highly significant (p<0.001). Conclusion Preop valgus knees show a significantly increased rotational laxity but no increased collateral ligament laxity compared to pre-operative varus knees six years after TKA with rotating platform. There is a significant difference in IKDC objective.

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Clinical Wear Measurement on Low Contact Stress Rotating Platform Knee Bearings

Cited by 55 publications

References 19 publications

Wear Damage in Mobile-bearing TKA is as Severe as That in Fixed-bearing TKA

Wear Damage in Mobile-bearing TKA is as Severe as That in Fixed-bearing TKA

Can Microcomputed Tomography Measure Retrieved Polyethylene Wear? Comparing Fixed-bearing and Rotating-platform Knees

Rotational laxity and collateral ligament laxity following total knee arthroplasty with rotating platform

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