Comparison of polyethylene tibial insert damage from in vivo function and in vitro wear simulation

Abstract

Function and wear of total knee arthroplasties were compared by analysis of damage patterns on polyethylene tibial inserts retrieved from patients (Group R) with inserts obtained after in vitro force-controlled knee joint wear simulation. Two simulator input profiles were evaluated, including standard walking (Group W), and combined walking and stair descent (Group W þ S), simulating varied activities and a more severe physiological environment. Damage regions on all inserts were quantitatively assessed. On average, inserts in all groups had internally rotated damage patterns and the greatest articular deformation in the lateral compartment. These patterns were more pronounced in Group W þ S compared to Group W. Deformation rates of simulated inserts were analogous to about six years of physiologic function. However, both groups of simulated inserts generally underestimated the magnitude of damage area and extent observed on retrieved inserts, consistent with differences in the simulator's tibiofemoral contact mechanics and those known to occur in patients during functional activities. Modification of simulator inputs, such as the increased anteroposterior excursion and more severe loading conditions in Group W þ S, can generate greater wear volume, larger damage areas, and increased surface deformation rates compared to standard inputs. ß

Polyethylene insert damage in unicondylar knee replacement: A comparison ofin vivofunction andin vitrosimulation

“…This study supports previous studies showing that damage patterns evident on polyethylene inserts after knee joint wear simulation under-predict damage observed on retrieved inserts [6,11]. Such disparity has been attributed to discrepancies between the simulators' articular contact mechanics [3][4][5][6][7][8][9][10][11] and variations in surface abrasion and lubrication [37,38] compared with the physiological conditions existing in vivo after knee joint replacement.…”

“…Such disparity has been attributed to discrepancies between the simulators' articular contact mechanics [3][4][5][6][7][8][9][10][11] and variations in surface abrasion and lubrication [37,38] compared with the physiological conditions existing in vivo after knee joint replacement. Possible explanations for the observed differences between the explanted and simulated UKR in the current study are that the short duration of simulated loading and range of motion did not fully represent the variety of conditions endured by the UKR during daily living activities.…”

Force-controlled dynamic wear testing of total ankle replacements

“…Wear simulator studies have been shown to be a powerful tool in predicting the wear performance of artificial joints for TKR and THR [16][17][18][19]. However, only a few studies have dealt with experimental wear studies on TAR [20][21][22].…”

Validation of a model-based measurement of the minimum insert thickness of knee prostheses

“…Subsequently, the circumference of both the insert periphery and the wear scars were digitised on calibrated digital images of the articular surface using published photogrammetry methods. 12,13 The insert circumference was used to map these data to the tibial model coordinate system.…”