Orientation of tendons in vivo with active and passive knee muscles

Aalbersberg, Sietske; Kingma, Idsart; Ronsky, Janet L.; Frayne, Richard; van Dieën, Jaap H.

doi:10.1016/j.jbiomech.2004.09.003

« Previous Next »Journal of Biomechanics
Volume 38, Issue 9 , Pages 1780-1788, September 2005

Orientation of tendons in vivo with active and passive knee muscles

Sietske Aalbersberg
- Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands
Idsart Kingma
- Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands
- Corresponding author. Tel.: +31204448492; fax: +31204448529.
Janet L. Ronsky
- Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Canada
Richard Frayne
- Departments of Radiology and Clinical Neurosciences, Seaman Family MR Research Centre, Foothills Medical Centre/University of Calgary, Calgary, Canada
Jaap H. van Dieën
- Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands

Accepted 9 September 2004. published online 16 November 2004.

Abstract

Tendon orientations in knee models are often taken from cadaver studies. The aim of this study was to investigate the effect of muscle activation on tendon orientation in vivo. Magnetic resonance imaging (MRI) images of the knee were made during relaxation and isometric knee extensions and flexions with 0°, 15° and 30° of knee joint flexion. For six tendons, the orientation angles in sagittal and frontal plane were calculated. In the sagittal plane, muscle activation pulled the patellar tendon to a more vertical orientation and the semitendinosus and sartorius tendons to a more posterior orientation. In the frontal plane, the semitendinosus had a less lateral orientation, the biceps femoris a more medial orientation and the patellar tendon less medial orientation in loaded compared to unloaded conditions. The knee joint angle also influenced the tendon orientations. In the sagittal plane, the patellar tendon had a more anterior orientation near full extension and the biceps femoris had an anterior orientation with 0° and 15° flexions and neutral with 30° flexions. Within 0° to 30° of flexion, the biceps femoris cannot produce a posterior shear force and the anterior angle of the patellar tendon is always larger than the hamstring tendons. Therefore, co-contraction of the hamstring and quadriceps is unlikely to reduce anterior shear forces in knee angles up to 30°. Finally, inter-individual variation in tendon angles was large. This suggests that the amount of shear force produced and the potential to counteract shear forces by co-contraction is subject-specific.

Abbreviations: ACL, Anterior cruciate ligament, BF, Biceps femoris, GR, Gracilis, MRI, Magnetic resonance imaging, PT, Patellar tendon, SM, Semimembranosus, SR, Sartorius, ST, Semitendinosus, TB, Tibia.