Maximilian J Hartel1, Yannick Loosli2, Daniel Delfosse3, Peter Diel4, Michael Thali5, Steffen Ross5, Sandro Kohl4, Stefan Eggli6. 1. Department of Trauma, Hand, and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Germany. Electronic address: mh@maxhartel.de. 2. Dr. h.c. Robert Mathys Foundation, Bettlach, Switzerland. 3. Mathys Ltd, Bettlach, Switzerland. 4. Department of Orthopedic Surgery, Inselspital, Bern University Hospital, Switzerland. 5. Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Switzerland. 6. Sonnenhof Orthopaedic Clinic, Swiss Leading Hospitals, Berne, Switzerland.
Abstract
BACKGROUND: Finding the right balance between tibial coverage and minimal implant overhang is an important factor in TKA. Another significant cause of failure is component malrotation. METHODS: An average master shape of the proximal tibia at TKA resection level was calculated using fine slice computed tomographies of 117 cadaveric knees. To find out whether alternate implant contours would be necessary depending on the patient's body size, we established five subgroups to compare. CAD-Analysis was performed to simulate the overhang produced after ±4°/±7°/±10° rotation. RESULTS: A master shape for the tibial resection cut (with a 5° posterior slope, 7 mm under lateral joint line) could be determined. Neither left vs. right knee joint, nor male vs. female nor the size subdivision appears to alter the calculated master shape significantly. The optimized shape allowing for ±4° of rotational freedom was found to be the best variant. CONCLUSIONS: Valid methods have been obtained to design a two-dimensional average shape of the tibial plateau. The modifications described in this study might come in useful, when designing future implant designs. CLINICAL RELEVANCE: An optimized fit at the tibial plateau and lower rates of component malrotation may result in better outcomes after TKA.
BACKGROUND: Finding the right balance between tibial coverage and minimal implant overhang is an important factor in TKA. Another significant cause of failure is component malrotation. METHODS: An average master shape of the proximal tibia at TKA resection level was calculated using fine slice computed tomographies of 117 cadaveric knees. To find out whether alternate implant contours would be necessary depending on the patient's body size, we established five subgroups to compare. CAD-Analysis was performed to simulate the overhang produced after ±4°/±7°/±10° rotation. RESULTS: A master shape for the tibial resection cut (with a 5° posterior slope, 7 mm under lateral joint line) could be determined. Neither left vs. right knee joint, nor male vs. female nor the size subdivision appears to alter the calculated master shape significantly. The optimized shape allowing for ±4° of rotational freedom was found to be the best variant. CONCLUSIONS: Valid methods have been obtained to design a two-dimensional average shape of the tibial plateau. The modifications described in this study might come in useful, when designing future implant designs. CLINICAL RELEVANCE: An optimized fit at the tibial plateau and lower rates of component malrotation may result in better outcomes after TKA.
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
Authors: Arnd Steinbrück; Andreas Fottner; Christian Schröder; Matthias Woiczinski; Markus Schmitt-Sody; Tatjana Müller; Peter E Müller; Volkmar Jansson Journal: Knee Surg Sports Traumatol Arthrosc Date: 2015-11-03 Impact factor: 4.342