What condition is characterized by pallor, absence of pulse, paralysis, and constant pain in a child with a supracondylar fracture of the humerus?

The condition characterized by pallor, absence of pulse, paralysis, and constant pain in a child with a supracondylar fracture of the humerus is best identified as Volkmann's ischemia. This condition typically arises from a lack of blood supply to the forearm muscles due to increased pressure, most often as a result of swelling in a closed compartment like in the case of compartment syndrome.

In the context of a supracondylar fracture, the damage to the blood vessels can lead to ischemia, resulting in the characteristic symptoms. Pallor indicates inadequate blood flow to the extremities, while absence of pulse suggests that the blood is not adequately perfusing the area. Paralysis points to potential nerve injury and compromised muscle function, and constant pain can be a direct consequence of ischemia and muscle necrosis that follows.

While compartment syndrome can lead to similar signs, Volkmann's ischemia specifically refers to the muscle necrosis and subsequent complications arising directly from ischemic conditions, particularly when associated with humeral fractures in children. Understanding this distinction is crucial as it guides the management and treatment of such complications.