Why range of motion in inversion and eversion of foot is increase and decreases

Increased Range of Motion:

• Ligamentous Laxity: When the ligaments supporting the ankle joint are more relaxed or have been stretched (e.g., due to previous sprains), they allow for greater movement, increasing inversion and eversion.
• Joint Capsule Flexibility: A more flexible joint capsule surrounding the talocrural and subtalar joints permits a wider arc of motion.
• Muscle Strength and Flexibility: While strong muscles stabilize the ankle, overly tight or inflexible muscles can sometimes restrict motion. Conversely, a good balance of strength and flexibility in the muscles that control inversion (e.g., tibialis posterior) and eversion (e.g., fibularis longus and brevis) is crucial for optimal range.
• Bone Structure: Variations in the shape and alignment of the tarsal bones can naturally allow for more or less movement.

Decreased Range of Motion:

• Ligamentous Tightness/Scarring: After an injury, if ligaments heal tightly or with scar tissue, they restrict movement.
• Muscle Tightness/Spasm: Tightness in the calf muscles (gastrocnemius, soleus) or the muscles responsible for inversion/eversion can limit the foot's ability to move into extreme positions.
• Arthritis or Joint Degeneration: Conditions like osteoarthritis can cause inflammation, pain, and the formation of bone spurs, which significantly reduce joint mobility.
• Swelling (Edema): Fluid accumulation in the ankle joint or surrounding tissues will physically impede movement.
• Improper Healing of Fractures: If bones in the foot or ankle heal in an altered position, it can restrict the normal mechanics of inversion and eversion.