Biomechanics & Gait Analysis Flashcards

In three-dimensional gait analysis, the 'sagittal plane' primarily captures which type of joint motion?

Answer: Flexion and extension

The sagittal plane divides the body into left and right halves; motions occurring in this plane are flexion and extension, which are the primary joint motions analyzed during gait.

Which of the following best describes 'functional leg length discrepancy' in the context of gait biomechanics?

Answer: An apparent difference in limb length caused by pelvic obliquity, hip contracture, or foot deformity

Functional leg length discrepancy arises from structural deformities or muscle imbalances (e.g., pelvic tilt, hip contracture, foot pronation) rather than true bony length differences.

The 'single limb support' phase of gait is biomechanically demanding because:

Answer: The entire body weight must be balanced over one foot, maximizing joint loading and muscle demand

During single limb support, all body weight is transferred to one limb, creating peak joint reaction forces at the hip, knee, and ankle while demanding coordinated muscle activity for balance.

A patient with a flaccid drop foot walks with a 'steppage gait.' The PRIMARY orthotic intervention to normalize this pattern is:

Answer: A dorsiflexion-assist AFO or posterior leaf spring AFO

A dorsiflexion-assist or posterior leaf spring AFO holds the foot in a neutral to slight dorsiflexion position, eliminating drop foot and the need for compensatory steppage gait.

When analyzing the biomechanics of the knee during normal gait, 'knee valgus moment' is most pronounced during which phase?

Answer: Loading response (early stance)

The knee valgus moment peaks during the loading response as body weight is rapidly accepted onto the limb, stressing medial compartment structures and the ACL.

Which clinical finding on static foot evaluation most strongly predicts excessive dynamic pronation during gait?

Answer: Compensated rearfoot varus with subtalar joint mobility

Compensated rearfoot varus with a mobile subtalar joint predicts dynamic pronation because the foot will pronate to bring the lateral forefoot to the ground during weight-bearing.

In gait analysis, 'pelvic drop' (contralateral pelvic tilt) during single limb support is a direct indicator of weakness in which muscle group of the stance limb?

Answer: Hip abductors (gluteus medius and minimus)

The hip abductors (gluteus medius and minimus) of the stance limb maintain pelvic level during single limb support; their weakness causes the pelvis to drop on the contralateral (swing) side.