Peter Kaiser1, Werner Schmoelz2, Philip Schoettle3, Marit Zwierzina4, Christian Heinrichs5, Rene Attal6. 1. Department of Trauma Surgery, Medical University of Innsbruck, Innsbruck, Austria. Electronic address: peter.kaiser@tirol-kliniken.at. 2. Department of Trauma Surgery, Medical University of Innsbruck, Innsbruck, Austria. Electronic address: werner.schmoelz@i-med.ac.at. 3. Department of Orthopaedic and Trauma Surgery, Isar Medical Center, Munich, Germany. Electronic address: p_schoettle@web.de. 4. Department of Anatomy, Embryology and Histology, Medical University of Innsbruck, Innsbruck, Austria. Electronic address: marit.zwierzina@i-med.ac.at. 5. Department of Trauma Surgery, Medical University of Innsbruck, Innsbruck, Austria. Electronic address: Christian.heinrichs@i-med.ac.at. 6. Department of Trauma Surgery, Medical University of Innsbruck, Innsbruck, Austria. Electronic address: rene.attal@tirol-kliniken.at.
Abstract
BACKGROUND: Increased internal femoral torsion is regarded as a risk factor for patellar instability. Biomechanical investigations confirming this hypothesis are missing. METHODS: Eight fresh-frozen cadaver knees were tested on a specially designed simulator. Patellar motion and patellofemoral pressure were evaluated for 0°, 10°, and 20° of increased internal and external femoral torsion with native and with transected medial patellofemoral ligaments used to simulate patellar instability. A regression analysis was used for statistical analysis. FINDINGS: In native medial patellofemoral ligaments, there were no significant changes in mean or peak pressures for any torsional states (P≥0.07). At 20° increased internal femoral torsion, there was a significant center of force shift towards the lateral side (P=0.01). Patellar shift was directed laterally at low knee flexion angles up to 30°. Lateral patellar tilt increased significantly at 10° and 20° of increased internal femoral torsion (P≤0.004). In transected medial patellofemoral ligaments, mean pressure (P≤0.005) and peak pressure (P≤0.02) decreased significantly for all torsional states. There was a significantly greater lateral center of force shift with increased internal femoral torsion (P≤0.04). Lateral patellar tilt increased significantly (P<0.001). Patellar shift did not change significantly with increased internal femoral torsion (P≥0.30). INTERPRETATION: In a native medial patellofemoral ligament, 20° of increased internal femoral torsion can be regarded as a significant risk factor for patellar instability. With an insufficient medial patellofemoral ligament, 10° of increased internal femoral torsion already represents a significant risk factor.
BACKGROUND: Increased internal femoral torsion is regarded as a risk factor for patellar instability. Biomechanical investigations confirming this hypothesis are missing. METHODS: Eight fresh-frozen cadaver knees were tested on a specially designed simulator. Patellar motion and patellofemoral pressure were evaluated for 0°, 10°, and 20° of increased internal and external femoral torsion with native and with transected medial patellofemoral ligaments used to simulate patellar instability. A regression analysis was used for statistical analysis. FINDINGS: In native medial patellofemoral ligaments, there were no significant changes in mean or peak pressures for any torsional states (P≥0.07). At 20° increased internal femoral torsion, there was a significant center of force shift towards the lateral side (P=0.01). Patellar shift was directed laterally at low knee flexion angles up to 30°. Lateral patellar tilt increased significantly at 10° and 20° of increased internal femoral torsion (P≤0.004). In transected medial patellofemoral ligaments, mean pressure (P≤0.005) and peak pressure (P≤0.02) decreased significantly for all torsional states. There was a significantly greater lateral center of force shift with increased internal femoral torsion (P≤0.04). Lateral patellar tilt increased significantly (P<0.001). Patellar shift did not change significantly with increased internal femoral torsion (P≥0.30). INTERPRETATION: In a native medial patellofemoral ligament, 20° of increased internal femoral torsion can be regarded as a significant risk factor for patellar instability. With an insufficient medial patellofemoral ligament, 10° of increased internal femoral torsion already represents a significant risk factor.
Authors: P Kaiser; F Loth; R Attal; M Kummann; P Schuster; F Riechelmann; M Schlumberger Journal: Knee Surg Sports Traumatol Arthrosc Date: 2019-07-02 Impact factor: 4.342
Authors: Ana Leal; Renato Andrade; Betina B Hinckel; Marc Tompkins; Paulo Flores; Filipe Silva; João Espregueira-Mendes; Elizabeth Arendt Journal: Knee Surg Sports Traumatol Arthrosc Date: 2019-06-28 Impact factor: 4.342
Authors: Florian B Imhoff; Victor Funke; Lukas N Muench; Andreas Sauter; Maximilian Englmaier; Klaus Woertler; Andreas B Imhoff; Matthias J Feucht Journal: Knee Surg Sports Traumatol Arthrosc Date: 2019-05-24 Impact factor: 4.342
Authors: Florian B Imhoff; Bastian Scheiderer; Philip Zakko; Elifho Obopilwe; Franz Liska; Andreas B Imhoff; Augustus D Mazzocca; Robert A Arciero; Knut Beitzel Journal: BMC Musculoskelet Disord Date: 2017-12-29 Impact factor: 2.362