True about Frozen shoulder.
**Core Concept**
Frozen shoulder, also known as adhesive capsulitis, is a condition characterized by stiffness and pain in the shoulder joint. It is a complex condition involving inflammation, fibrosis, and contracture of the shoulder capsule.
**Why the Correct Answer is Right**
The pathophysiology of frozen shoulder involves an initial inflammatory phase, followed by a fibrotic phase and finally a contracture phase. During the inflammatory phase, there is an increase in prostaglandins and other inflammatory mediators, leading to pain and stiffness. The fibrotic phase is characterized by the deposition of collagen and other extracellular matrix proteins, resulting in thickening of the shoulder capsule and further contracture. This leads to a decrease in the range of motion of the shoulder joint.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while pain is a symptom of frozen shoulder, it is not the primary characteristic of the condition.
**Option B:** This option is incorrect because while fibrosis is a component of frozen shoulder, it is not the only factor contributing to the condition.
**Option C:** This option is incorrect because while contracture is a result of frozen shoulder, it is not the primary cause of the condition.
**Clinical Pearl / High-Yield Fact**
It is essential to differentiate between frozen shoulder and other conditions such as osteoarthritis, rotator cuff tears, and adhesive capsulitis of the hip. A thorough physical examination and imaging studies are necessary to make an accurate diagnosis.
**Correct Answer:** D