Meeting Abstract
P3.149 Monday, Jan. 6 15:30 Length changes of the human iliotibial band in relation to hip motion ENG, CM*; ARNOLD, AS; LIEBERMAN, DE; BIEWENER, AA; Harvard University; Harvard University; Harvard University; Harvard University cmeng@fas.harvard.edu
The human iliotibial band (ITB) is a complex fascial structure crossing the hip and knee and its role in locomotion is poorly understood. A role for the ITB in lateral hip stabilization has been previously proposed. We suggest that the ITB may also function to store and recover elastic energy. The ITB’s ability to perform these functions during locomotion depends on its length changes and stresses, which are influenced by the ITB’s moment arms (MAs), its material properties, and forces generated by in-series muscles. To test hypotheses about ITB function, MAs and muscle force estimates were obtained from 5 fresh human limbs. MAs of gluteus maximus (GMax) and tensor fascia lata (TFL) muscles inserting on the ITB (i.e., ITB muscle-tendon units) for hip flex/extension and ab/adduction were obtained by the tendon excursion method. Portions of GMax and TFL inserting on the ITB were weighed to estimate the force that these muscles potentially transmit to the ITB. Because muscles that insert on the ITB are located superficially on the thigh, these MTUs have large hip MAs. While all GMax regions have MAs that extend the hip, proximal GMax has a hip abduction MA while distal GMax has a hip adduction MA. The antagonistic hip ab/adduction MAs of GMax may keep the ITB taut during the stance phase to laterally stabilize the limb. The large hip extension MAs of GMax may stretch the ITB during hip flexion and store elastic energy, suggesting the human ITB may play dual roles during locomotion. We estimated that all of TFL and as much as 50% of GMax fibers insert on the ITB. Overall, these data indicate that due to large hip MAs and the potential for substantial muscle loading, ITB undergoes large length changes during locomotion. These data will be integrated with a musculoskeletal model to further explore ITB function.
