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Orthopedic Research Online Journal

The Effect of Patellar Button Placement on Gait and Patellar Stresses Following Total Knee Arthroplasty

Submission: November 01, 2019;Published: November 08, 2019

DOI: 10.31031/OPROJ.2019.06.000631

ISSN : 2576-8875
Volume6 Issue2


Background: In total knee arthroplasty with patellar resurfacing, surgeons are often faced with a choice of where to position the patellar button. Patellar button positioning has been studied in relation to patellar tracking and risk of subluxation. Consequently, medial placement has been recommended. However, postoperative gait and risk of periprosthetic complications have not been thoroughly addressed in relation to patellar button positioning.

Objective: To establish a generalized criterion for patellar button positioning during total knee replacement (TKA) to reduce the risk of postoperative gait abnormalities, patellar fracture, pain, and stress wear.

Methods: Five distinct button positions were analyzed. A previously-validated gait model was customized with data obtained from cadaveric patellae to evaluate individual quadriceps forces. The maximal combined quadriceps force during gait was applied to a finite element analysis model to calculate patellar von Mises stresses for all button positions, as well as for a large diameter button covering most of the patellar resurfaced area.

Results: Significant differences were found in average forces exercised by individual quadriceps muscles during gait. Distal and medial configurations produced the lowest individual quadriceps muscle forces. Bone stress ranged from 12.45MPa to 12.57MPa. The button stress ranged from 11.27MPa to 17.20 MPa, with distal and centered placement, respectively.

Conclusion: Patellar button positioning influences muscle forces during gait and affects the stress on the patellar button itself. Distal and medial button positions are more likely to optimize postoperative gait kinematics, while the distal position may reduce button wear. These findings provide further insight into patellar button placement.

Keywords: Total knee arthroplasty; Knee replacement; Patellar button; Patellar resurfacing; Gait

Abbreviations: TKA: Total Knee Arthroplasty; UHMWPE: Ultra High Molecular Weight Polyethylene; CT: Computerized Tomography; [%BW]: Percent Body Weight; [deg]: Degrees

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