Biomechanical assessment of gait problems

The variations in human gait depend on biomechanical differences unique for every individual, such as physical activity, age, normal walking patterns, and pathological conditions that result in an abnormal gait.

Differences in anthropometric measurements, stride length and speed contribute to varying gait patterns.

In clinical settings, clinicians use subjective observation to analyse gait. The biomechanical assessment of the patient's lower limb involves analysis, assessment, and evaluation of joint range of motion, muscle action, and walking pattern, from anterior, posterior, and lateral views.

The patient is assessed based on the following anatomical components:

• Lumbopelvic control
• Hip muscle control (intrinsic stability)
• Hip range of motion
• Knee and ankle muscle control
• Foot position
• Proprioception and balance

Normal biomechanical lower limb assessment checklist

Spine    
•    Lordosis/kyphosis
•    Lateral scoliosis
•    Rotational scoliosis

Pelvis    
•    Ant/post tilt
•    Elevated/depressed
•    Rotation

Femur    
•    Internal/external rotation
•    Hip
•    Flex/extension
•    Adduction/abduction

Tibia    
•    Internal/external torsion
•    Knee
•    Flex/extension
•    Varum/valgum

Ankle    
•    Plantar flexion
•    Dorsiflexion
•    Varus/valgus

Foot    
•    Toe flex/ext
•    Pronation/supination
•    Adduction/abduction

Biomechanical parameters for gait analysis 

Gait involves a complex interaction between the neuromuscular and skeletal muscle coordination. Failure of either of these systems can cause movement disabilities.

Certain biomechanical parameters are used to identify the abnormal gait, including gait velocity, cadence, stride length, joint angles.

Another conventional method to identify gait deviation is spatiotemporal gait assessment.

The phases of a normal gait cycle:

• Initial contact
• Mid stance 
• Terminal stance
• Push off 
• Pre swing
• Initial swing
• Mid swing 
• Terminal swing

The biomechanics of the lower limb depend on the musculoskeletal model proposed by Arnold et al. A musculoskeletal model is made up of bones, muscle-tendon segments, ligaments, and wrapping materials. Joint mobility is contingent upon the appropriate activation of every muscle group.

The body segments that make up the musculoskeletal model of the lower limb (including both legs) are the torso, pelvis, left and right femur, tibia, patella, talus, calcaneus, and toes.

The musculoskeletal model is used to estimate the joint position, acceleration and velocity of movement to achieve the normal position and gauge the effect of multidirectional forces and torque produced on joint motion.

Gait problems

Pathological gait is often characterised by abnormal biomechanical patterns.

Gait abnormalities can develop due to neurological conditions such as stroke, Parkinson's, cerebral palsy, cerebral ataxia, or myelodysplasia, or due to trauma, injury or neuropathy such as peripheral neuropathy, femoral nerve neuropathy, etc.

The basis of treatment is an understanding of the elements of a typical human motion.

The common biomechanical pathological gait is summarised here:

- Dr Humda, Physiotherapist

Learn more about this topic in the HealthCert Professional Diploma program in Musculoskeletal & Sports Medicine - fully online or with optional practical workshops.