**Question:** The following fractures are known for non-union except

A. Humerus shaft
B. Radius shaft
C. Clavicle
D. Pelvic ring fracture

**Core Concept:** A non-union fracture is a failure of a fracture to unite despite proper treatment. A non-union can lead to complications like deformity, loss of function, and pain.

**Why the Correct Answer is Right:** A pelvic ring fracture is an exception to the rule because it has a high propensity for non-union due to its unique anatomy. The pelvic ring is composed of two acetabular fragments (superior and inferior) and two pubic ramus fragments (anterior and posterior). The high variability in fracture patterns and the presence of a fibrous joint capsule make it challenging for these fractures to unite.

**Why Each Wrong Option is Incorrect:**

A. Humerus shaft fractures typically heal well because the bone is long, straight, and has a large blood supply.
B. Radius shaft fractures also usually heal well due to these favorable factors.
C. Clavicle fractures are typically treated conservatively, and the blood supply to the clavicle is adequate, making it less prone to non-union compared to pelvic ring fractures.

**Clinical Pearl / High-Yield Fact:** For optimal management of pelvic ring fractures, it is essential to assess the fracture patterns, stabilize the fracture, and consider early weight-bearing to promote healing. In cases of delayed or non-union, surgical intervention may be necessary.