Answer :
Final answer:
The deformity characterized by proximal interphalangeal joint flexion and distal interphalangeal joint hyper-extension is called Swan neck deformity. This condition is commonly associated with chronic joint issues like rheumatoid arthritis.
Explanation:
The deformity described, where the proximal interphalangeal joints are flexed and the distal interphalangeal joints are hyper-extended, is known as Swan neck deformity. This condition can be seen in various medical situations, including rheumatoid arthritis.
The name "Swan neck" comes from the resemblance of the finger's shape to that of a swan's neck. This deformity is a result of an imbalance in the muscle and ligament mechanisms that control finger movements, often stemming from conditions that cause chronic inflammation or damage to the joint structures.
Hypertexture and hyperflexion are key terms when discussing joint movements. Hyperextension is the abnormal or excessive extension of a joint beyond its normal range, while hyperflexion refers to excessive flexion at a joint. These concepts are essential in understanding how Swan neck deformity develops, as the condition involves hyperextension of the distal interphalangeal joint and flexion of the proximal interphalangeal joint.
