**Core Concept**
The Gustilo Anderson classification is a grading system used to categorize the severity of open fractures based on the extent of soft tissue damage and the size of the wound. This classification helps orthopedic surgeons to plan the appropriate treatment and predict the outcome of patients with open fractures.

**Why the Correct Answer is Right**
The Gustilo Anderson classification is a widely accepted system that grades open fractures from Type I (clean wound with minimal soft tissue damage) to Type III (extensive soft tissue damage and large wound size). The classification is based on the size of the wound, the presence of neurovascular damage, and the extent of soft tissue damage. For example, Type IIIA fractures have a wound size of more than 10 cm in length, with extensive soft tissue damage and some bone exposure, but without significant neurovascular damage. Type IIIB fractures have a similar wound size and soft tissue damage, but with significant neurovascular damage. Type IIIC fractures have a wound size of more than 10 cm in length, with extensive soft tissue damage, significant neurovascular damage, and an associated vascular injury.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because the Gustilo Anderson classification is specifically used for open fractures, not for closed fractures or other types of injuries.
**Option B:** This is incorrect because the Mangled Extremity Severity Score (MESS) is a different grading system used to evaluate the severity of traumatic injuries, not the Gustilo Anderson classification.
**Option C:** This is incorrect because the Orthopedic Trauma Association (OTA) classification is used for closed fractures, not for open fractures.

**Clinical Pearl / High-Yield Fact**
The Gustilo Anderson classification is an essential tool for orthopedic surgeons to evaluate the severity of open fractures and plan appropriate treatment. It is essential to remember that Type III fractures are associated with a higher risk of infection and poor outcomes.

**Correct Answer: D. Gustilo Anderson classification is used for open fractures.**