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Title: Investigation of wear within the patellofemoral joint of total knee replacements
Author: Ellison, Peter
ISNI:       0000 0001 3446 686X
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2007
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Quantification of in vitro wear rates is· now considered an essential step in the development of a new joint replacement prior to clinical trial. However, little research exists around in vitro simulation of wear in the patellofemoral joint (pFJ) despite over 200,000 being implanted annua.lly within the Eur~pean Union. A method of simulating wear using four active degrees of freedom within the PFJ of a commercially available total knee replacement (TKR) has been developed.. As part of the development of the wear simula~ion methodology a computational model of the proposed simulator was created. A control strategy suitable for the simulation of wear during gait was defined in terms. of kineIIl:atics and kinetic inputs. The control strategy was tested in the comp\ltational simulator. The kinematics response of the unconstrained DOF was similar to PFJ kinematics presented in the literature, 'confirming that the simulator design and control strategy was capable of replicating the joints basic biomechanical conditions. The model was used to perform a simple parametric study comparing differences in kinematics response when using four designs of TKR PFJ. Results clearly showed significant variation between designs. Little is known regarding the kinematic behaviour of designs of TKR PFJ. The interactions between design and kinematics are important in determining wear and thus the computational simulator presented acts as a valuable tool in the further investigation of PFJ performance and wear. Little data exists detailing the in vivo wear of the PFJ of TKR. As this information is essential to the validation of any in vitro wear methodology a retrieval study was carried out in order to quantify in vivo wear. Wear scar area was found to be the most repeatable metho.d of in vivo wear quantification. A series of 24 retrieved TKR prostheses, consisting of 9 designs of PFJ were analysed along with the associated patient data. On average the wear scar formed a band spanning in the ~-L direction with an area of 364.32±64.7mm2 (mean (n=24) ± 95% CI). These values compared positively to previously published data. Hood, et al. 's [1] methodology for the characterisation of UHMWPE surface damage modes was· used to assess damage of the retrieved patellae. The results from the .application of this technique were questioned as it did ~ot account for the chronological
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available