**Question:** Bohler's angle is used in fracture of ?

A. Talus
B. Calcaneus
C. Os calcis
D. Tarsal bones

**Core Concept:**
Bohler's angle is an important radiographic parameter used in assessing the stability of fractures involving the calcaneus (heel bone). It is a measure of the relationship between the calcaneus and the tibiocalcaneal joint. The normal Bohler's angle is approximately 20-30 degrees.

**Why the Correct Answer is Right:**
Bohler's angle is specifically used in fractures involving the calcaneus (heel bone), which is part of the tarsal bones. Calcaneus is a crucial component of the ankle complex and Bohler's angle helps in evaluating the stability of a fracture and assessing the need for surgical intervention.

**Why Each Wrong Option is Incorrect:**
A. Talus (tarsal bone) is incorrect because Bohler's angle is used for fractures involving the calcaneus (heel bone), not the talus (ankle bone).
B. Calcaneus (heel bone) is incorrect because the question specifically asks about Bohler's angle, which is related to fractures involving calcaneus.
C. Os calcis (Latin term for calcaneus) is incorrect as it is synonymous with calcaneus and the question asks for the application of Bohler's angle.
D. Tarsal bones are incorrect because the question focuses on fractures involving calcaneus, not tarsal bones in general.

**Clinical Pearl:**
Understanding Bohler's angle is crucial for orthopedic surgeons and radiologists assessing calcaneal fractures. A reduced or absent Bohler's angle indicates unstable fractures that may require surgical intervention to attain proper fracture reduction and maintain ankle joint stability.