Biomechanics Flashcards
Biomechanics of a desk based job for someone with AC OA
§ Prolonged sitting with poor posture, like rounded shoulders and a forward head, increases stress on the AC joint, worsening OA symptoms. Inactivity also leads to joint stiffness, which can progressively limit mobility. Regular movement and posture adjustments help reduce strain and maintain joint function.
§ Muscle imbalances: Prolonged sitting and repetitive desk work can lead to weakening of certain muscle groups and tightening of others. This imbalance can alter the biomechanics of the shoulder complex, potentially accelerating the progression of AC OA.
§ Increased inflammation: Sedentary behaviour has been associated with increased inflammation in the body. For individuals with AC OA, this could lead to more frequent flare-ups and increased pain.
Individuals with AC OA working desk-based jobs should
- Take regular breaks to move and stretch
- Ensure proper ergonomic setup of their workstation
- Incorporate exercises to strengthen the shoulder and upper back muscles
- Maintain good posture throughout the day
- Consider using standing desks or other alternatives to reduce sedentary time
Long-distance driving can predispose individuals to AC OA due to several biomechanical factors:
§ Prolonged static posture
§ Muscle fatigue
§ Steering wheel grip: Gripping the steering wheel, especially in suboptimal positions, can place continuous stress on the shoulder complex, including the AC joint. Research has shown that different driving postures can significantly affect muscle activation and joint forces.
§ Vibration and micro-traumas: The constant vibration from the vehicle, combined with sudden movements or corrections while steering, can cause repetitive micro-traumas to the AC joint. These small, repeated stresses may contribute to the development of OA over time.
§ Acceleration-deceleration forces: Sudden braking or acceleration can subject the AC joint to acceleration-deceleration forces. Studies have shown that these forces can cause injury to the AC joint, potentially leading to long-term issues like OA.
§ Arm position: Driving with the arm in an elevated or outstretched position for long periods can increase the load on the AC joint. Research indicates that driving positions further from the steering wheel lead to higher muscle activations and joint force
Biomechanical Interactions of her past medical Hx
§ Postural Compensation: SIJ OA and degenerative disc disease at L4/L5 can lead to altered pelvic alignment and lumbar spine instability, which may affect overall posture. This can shift the mechanics of the upper body, increasing stress on the shoulder girdle and exacerbating AC OA symptoms.
§ Kinetic Chain Disruption: Hallux rigidus limits proper foot mechanics during walking, leading to compensatory movements in the lower extremities, pelvis, and spine. These compensations can travel up the kinetic chain, altering shoulder biomechanics and aggravating AC OA.
§ Increased Joint Stress: Degenerative changes in the SIJ and lumbar spine reduce mobility and stability in the lower body, forcing greater reliance on upper body movements for functional tasks. This increased demand on the AC joint may accelerate degeneration or worsen pain.
Muscle Imbalances:
Functional Impacts of past medical Hx
Reduced Mobility: Pain and stiffness from SIJ OA, L4/L5 degeneration, and hallux rigidus can limit physical activity, leading to reduced range of motion in all joints, including the shoulder. This inactivity may worsen AC OA stiffness.
Difficulty with Weight-Bearing Activities: Hallux rigidus limits proper toe-off during walking, while SIJ pain affects pelvic stability during weight-bearing activities. These limitations may force compensatory use of the upper body for tasks like lifting or carrying, further straining the AC joint.
Pain Amplification: Chronic pain from multiple sources (SIJ, spine, foot) may lead to heightened sensitivity or referred pain patterns that overlap with AC OA symptoms, complicating diagnosis and management.
