In ankle sprain, the commonest ligament torn is?
**Core Concept**
The most common ligament injured in an ankle sprain is the lateral collateral ligament, which provides stability to the ankle joint. This ligament is prone to injury due to its location on the outside of the ankle, making it susceptible to inversion injuries.
**Why the Correct Answer is Right**
The lateral collateral ligament consists of three parts: the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL). The ATFL is the most commonly injured part due to its role in stabilizing the ankle joint against inversion forces. During an inversion injury, the foot rolls inward, causing the ATFL to stretch or tear, leading to ankle instability.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as the medial collateral ligament (MCL) is more commonly associated with knee injuries, not ankle sprains.
* **Option B:** The deltoid ligament is a strong ligament that provides medial stability to the ankle joint, making it less likely to be injured in an ankle sprain.
* **Option C:** The posterior talofibular ligament (PTFL) is a part of the lateral collateral ligament complex but is less commonly injured than the anterior talofibular ligament (ATFL).
**Clinical Pearl / High-Yield Fact**
Remember the "ATFL" acronym to associate with ankle sprains: "Ankle Torsion Forces Lead" to injury of the Anterior Talofibular Ligament.
**Correct Answer: C. Lateral collateral ligament.**