In vitro wear of unicompartmental knee replacements—the effects of kinematics and femoral condylar lift-off on a fixed bearing design

Burton, Andrew; McEwen, H.M.J.; Farrar, R.; Stone, Martin; Jennings, Louise; Fisher, John

doi:10.1016/s0021-9290(06)83469-x

Cited by 8 publications

(4 citation statements)

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“…The application of a loading profile as recommended by ISO 14243-1 for TKR did prove comparable wear results with a previous similar experience (Burton et al 2006) in the case of a traditional metallic holding system. This might confirm the efficiency of such an orthopaedic procedure for restoring good mobility and appropriate kinematics in the case of unilateral knee arthritis.…”

Section: Discussionsupporting

confidence: 75%

Unicompartmental knee prostheses:in vitrowear assessment of the menisci tibial insert after two different fixation methods

et al. 2008

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Knee osteoarthritis is a complex clinical scenario where many biological and mechanical factors influence the severity of articular degenerative changes. Minimally invasive knee prosthetic surgery, with only a compartment replacement (unicompartmental knee replacement), might be a good compromise between osteotomy and total knee prosthesis. The focus of this study was to develop and validate a protocol to assess the fixation method of the femoral components in mechanical simulation, for pre-clinical validation; the wear behaviour of two different fixation frames was quantified and compared. In particular, two different wear tests were conducted using the same knee simulator, the same load profiles and the same kinematics; two different fixation methods were applied to the femoral sleds (synthetic femur and metal block). Surface characterization on both articulating bearings was performed by a roughness measuring machine and coordinate measuring machine. The wear produced by the tibial inserts using the synthetic femur was considerably higher than the wear registered by the metal-block holder. Roughness measurements on femoral sleds showed a limited number of scratches with high R(t) values for the metal-block set-up; the damaged surface broadened in the case of femoral condyles and tibial inserts mounted on composite bone, but lower R(t) and linear penetration values were measured. The two holding frames showed different wear activities as a consequence of dissimilar dynamic performance. Further observations should be made in vivo to prove the actual importance of synthetic bone simulations and specific material behaviour.

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Section: Discussionsupporting

confidence: 75%

Unicompartmental knee prostheses:in vitrowear assessment of the menisci tibial insert after two different fixation methods

et al. 2008

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“…Previous experimental studies have suggested that there are differences between the wear performance of medial and lateral unicompartmental bearings, significant in some studies, when configured such that they can be tested in parallel [26][27][28]. The differences in wear performance may be attributed to the offset in loading, and different sliding patterns on each condyle.…”

Section: Introductionmentioning

confidence: 99%

The wear of fixed and mobile bearing unicompartmental knee replacements

Brockett

Jennings

Fisher

2011

Proc Inst Mech Eng H

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Unicompartmental knee replacements (UKR) are an option for surgical intervention for the treatment of single-compartment osteoarthritis. The aim of this study was to compare the wear of a low-conformity fixed-bearing UKR with a conforming mobile bearing UKR under two kinematic conditions, to investigate the effect of implant design and kinematics on wear performance in a physiological knee wear simulator. Under both sets of kinematic conditions, the relatively low-conforming fixed UKR showed lower wear, compared with the more conforming anterior-posterior sliding mobile bearing. However, it should be noted that differences in materials between the two designs also contribute to the relative wear performance of the bearings. The combined wear of the medial and lateral bearings of the fixed-bearing UKR as a 'total knee' were significantly reduced compared with a fixed-bearing total knee replacement studied under the same kinematic conditions.

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“…Still, the surgical procedure for Bi-UKR is technically more demanding and considered less reproducible than for TKR, as the components require implantation accuracy greater than that required for TKR [3,4]. This surgical variability impacts knee function and clinical outcomes after UKR [2][3][4][5][6][7][8][9]. Knee prosthesis function varies depending on prosthesis geometry, kinematic conditions, and the absence/presence of soft-tissue constraints after knee replacement surgery.…”

Section: Introductionmentioning

confidence: 99%

“…Representing these performance characteristics during in vitro knee wear joint simulation and other pre-clinical assessments of UKR has proved difficult [5,8,12]. The aforementioned wear tests [5,8,12,13] were conducted using displacement-controlled (DC) simulators, which are supposed to mimic the various kinematic conditions of the normal knee function, under a standardized input protocol (ISO 14243 -3, 2004 [14]). This standard defines the flexion/extension rotation (F/E; degrees), anterior/ posterior movement (A/P; mm), internal/external rotation (I/E; degrees), and axial (compressive) load patterns (N) of a TKR during an entire gait cycle.…”

Section: Introductionmentioning

confidence: 99%

Bi-unicondylar knee prosthesis functional assessment utilizing force-control wear testing

Spinelli

Affatato

Harman

et al. 2009

Proc Inst Mech Eng H

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Recent in vivo studies have identified variations in knee prosthesis function depending on prosthesis geometry, kinematic conditions, and the absence/presence of soft-tissue constraints after knee replacement surgery. In particular, unicondylar knee replacements (UKR) are highly sensitive to such variations. However, rigorous descriptions of UKR function through experimental simulation studies, performed under physiological force-controlled conditions, are lacking. The current study evaluated the long-term functional performance of a widely used fixed-bearing unicompartmental knee replacement, mounted in a bi-unicondylar configuration (Bi-UKR), utilizing a force-controlled knee simulator during a simulated (ISO 14243) walking cycle. The wear behaviour, the femoral-tibial kinematics, and the incurred damage scars were analysed. The wear rates for the medial and the lateral compartments were 10.27 +/- 1.83 mg/million cycles and 4.49 +/- 0.53 mg/million cycles, respectively. Although constant-input force-controlled loading conditions were maintained throughout the simulation, femoral-tibial contact point kinematics decreased by 65 to 68 per cent for average anterior/posterior travel and by 58 to 74 per cent for average medial/lateral travel with increasing cycling time up to 2 million cycles. There were no significant differences in damage area or damage extent between the medial and the lateral compartments. Focal damage scars representing the working region of the femoral component on the articular surface extended over a range of 16-21 mm in the anterior-posterior direction. Kinematics on the shear plane showed slight variations with increasing cycling time, and the platform exhibited medial pivoting over the entire test. These measures provide valuable experimental insight into the effect of the prosthesis design on wear, kinematics, and working area. These functional assessments of Bi-UKR under force-controlled knee joint wear simulation show that accumulated changes in the UKR articular conformity manifested as altered kinematics both for anterior/posterior translations and internal/external rotations.

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In vitro wear of unicompartmental knee replacements—the effects of kinematics and femoral condylar lift-off on a fixed bearing design

Cited by 8 publications

References 0 publications

Unicompartmental knee prostheses:in vitrowear assessment of the menisci tibial insert after two different fixation methods

Unicompartmental knee prostheses:in vitrowear assessment of the menisci tibial insert after two different fixation methods

The wear of fixed and mobile bearing unicompartmental knee replacements

Bi-unicondylar knee prosthesis functional assessment utilizing force-control wear testing

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