Thoracic compliance decreased in cases of kyphosis, scoliosis, arthritis, skeletal muscles diseases and obesity

Thoracic compliance refers to the ease with which the thoracic wall (rib cage, intercostal muscles, and diaphragm) can expand and contract. A decrease in compliance means the thoracic wall becomes stiffer and harder to move, requiring more effort to breathe.

Here's why the listed conditions decrease thoracic compliance:

• Kyphosis and Scoliosis: These are spinal deformities that alter the normal curvature of the spine and the alignment of the rib cage. This structural change restricts the expansion and flexibility of the chest wall, making it less compliant.
• Arthritis: Inflammation of the joints, particularly those connecting the ribs to the vertebrae and sternum (costovertebral and costosternal joints), can cause pain and stiffness. This reduces the mobility of the rib cage, thereby decreasing thoracic compliance.
• Skeletal Muscle Diseases: Conditions like muscular dystrophy or amyotrophic lateral sclerosis (ALS) weaken or paralyze the respiratory muscles (intercostals, diaphragm). These muscles are essential for moving the thoracic wall, so their impairment directly reduces the chest wall's ability to expand, leading to decreased compliance.
• Obesity: Excessive fat accumulation on and around the chest wall and abdomen adds significant weight and resistance. This extra load makes it harder for the respiratory muscles to move the thoracic cage, effectively stiffening the system and reducing thoracic compliance.