**Question:** Commonest complication of extra capsular interochanteric fracture of neck of femur is:

A. Hip dislocation
B. Subcutaneous emphysema
C. Deep vein thrombosis (DVT)
D. Tuberculosis

**Core Concept:**
Extra-capsular interochanteric fracture of the neck of the femur is a type of hip fracture characterized by a fracture extending through the neck of the femur, just outside the joint capsule. These fractures are generally less severe and have a better prognosis compared to intracapsular fractures. However, a major concern in the management of these fractures is the potential for complications.

**Why the Correct Answer is Right:**
The correct answer is C: Deep vein thrombosis (DVT). DVT is a common complication in patients with hip fractures, including extra-capsular interochanteric fractures. The reason for this is the immobilization of the patient due to fracture fixation, which leads to reduced mobility and increased risk of blood clot formation in the legs.

**Why Each Wrong Option is Incorrect:**
A. Hip dislocation: Hip dislocation is a different type of hip fracture, where the head of the femur is displaced from its socket. It is not a complication of extra-capsular interochanteric fractures.

B. Subcutaneous emphysema: This is a complication related to lung injuries or pneumothorax, not a complication of hip fractures. Subcutaneous emphysema occurs when air enters the subcutaneous tissues, causing swelling and skin discoloration. It is unrelated to hip fractures.

D. Tuberculosis: This is a bacterial infection and not a complication of hip fractures. Although tuberculosis can affect the hip joint, the correct answer should focus on the specific complication related to the fracture and its treatment.

**Clinical Pearl:**
In patients with extra-capsular interochanteric fractures, clinicians should closely monitor for the development of Deep Vein Thrombosis (DVT) due to the immobilization caused by fracture fixation. Proper management, including prophylactic measures like compression stockings, intermittent pneumatic compression devices, and low molecular weight heparin, can help reduce the risk of DVT in these patients. Early mobilization of the patient is also essential to prevent DVT and other complications associated with prolonged immobilization.