Malin Meier1, Sumesh Zingde2, Raymond Best1, Lennart Schroeder3, Johannes Beckmann1, Andre Friedrich Steinert4. 1. Sportklinik Stuttgart, Taubenheimstrasse 8, 70372, Stuttgart, Germany. 2. Conformis Inc, 600 Technology Park Dr, Billerica, MA, 01821, USA. 3. Julius-Maximilians-Universitaet Wuerzburg, Sanderring 2, 97070, Würzburg, Germany. 4. Krankenhaus Agatharied, Norbert-Kerkel-Platz, 83734, Hausham, Germany. andre.steinert@outlook.de.
Abstract
PURPOSE: As the correct rotational and sagittal alignment of the tibial tray are of key importance for optimal total knee arthroplasty (TKA) function, the objective of this study was to determine these individual variations in the proximal tibial geometry in terms of posterior tibial slope (PTS) and tibial surface asymmetry by analysing a large dataset of computer tomography (CT) information. METHODS: A retrospective two-part review was performed on 15,807 datasets that were generated during the design phase for a customized TKA implant. First, 15807 CAD (computer-aided-design) models derived from CT data were used to conduct the analysis on the variation of the PTS. Second, the axial cut of each proximal tibia in a consecutively selected subset of 2202 datasets was used to measure the tibial asymmetry. RESULTS: The majority (65.5%) of tibiae had a posterior slope between 5° and 10°, while 26.5% of knees had a slope > 10°. The asymmetry measured as offset between the lateral and medial posterior boundaries was highly variable, with overall an increasing proportion of patients with high asymmetry with increasing tibial ML width. Only 14% of tibiae exhibited symmetric (< 2 mm offset) lateral and medial plateaus, and 22% had an offset > 5 mm. CONCLUSION: This study from an extraordinary large data base reveals that tibial posterior slope and asymmetry of the tibial profile vary largely between patients receiving TKA with increasing tibial asymmetry with ML width. CT scans might help to preoperatively better select the best fitting TKA, otherwise surgeons intraoperatively will often have to deal with compromises regarding fitting, sizing and rotational issues. LEVEL OF EVIDENCE: Retrospective case series, Level IV.
PURPOSE: As the correct rotational and sagittal alignment of the tibial tray are of key importance for optimal total knee arthroplasty (TKA) function, the objective of this study was to determine these individual variations in the proximal tibial geometry in terms of posterior tibial slope (PTS) and tibial surface asymmetry by analysing a large dataset of computer tomography (CT) information. METHODS: A retrospective two-part review was performed on 15,807 datasets that were generated during the design phase for a customized TKA implant. First, 15807 CAD (computer-aided-design) models derived from CT data were used to conduct the analysis on the variation of the PTS. Second, the axial cut of each proximal tibia in a consecutively selected subset of 2202 datasets was used to measure the tibial asymmetry. RESULTS: The majority (65.5%) of tibiae had a posterior slope between 5° and 10°, while 26.5% of knees had a slope > 10°. The asymmetry measured as offset between the lateral and medial posterior boundaries was highly variable, with overall an increasing proportion of patients with high asymmetry with increasing tibial ML width. Only 14% of tibiae exhibited symmetric (< 2 mm offset) lateral and medial plateaus, and 22% had an offset > 5 mm. CONCLUSION: This study from an extraordinary large data base reveals that tibial posterior slope and asymmetry of the tibial profile vary largely between patients receiving TKA with increasing tibial asymmetry with ML width. CT scans might help to preoperatively better select the best fitting TKA, otherwise surgeons intraoperatively will often have to deal with compromises regarding fitting, sizing and rotational issues. LEVEL OF EVIDENCE: Retrospective case series, Level IV.
Authors: Lucas Beckers; Jacobus H Müller; Jeremy Daxhelet; Salvatore Ratano; Mo Saffarini; Tarik Aït-Si-Selmi; Michel P Bonnin Journal: Knee Surg Sports Traumatol Arthrosc Date: 2021-06-01 Impact factor: 4.342