The most common cause of Volkmann’s ischaemic contracture in a child is –
The core concept here is the pathophysiology of Volkmann's contracture. It's usually due to compartment syndrome, which causes muscle necrosis from prolonged ischemia. In children, the most common cause is a supracondylar fracture of the humerus. This is because the anterior compartment of the forearm is supplied by the brachial artery, and if there's swelling or bleeding after the fracture, it can increase pressure and compromise blood flow.
Now, the options are missing, but I can infer possible distractors. Common wrong options might include other types of fractures, like a spiral fracture of the tibia, or conditions like burns causing compartment syndrome. Another possibility is a radial head fracture, but that's more common in adults. Also, maybe something like a brachial artery injury from a penetrating wound, but that's less common in kids.
The correct answer is the supracondylar humerus fracture. I need to explain why this is the most common. The mechanism would involve the fracture leading to swelling and increased pressure in the forearm compartments, especially the anterior one, which is supplied by the brachial artery. If not treated promptly with fasciotomy, the muscles (like flexor digitorum profundus) contracture, leading to the characteristic claw hand.
For the incorrect options, if one of the options is a spiral fracture of the tibia, that's a common cause in adults, especially from motorcycle accidents, but not in children. A radial head fracture is more associated with elbow dislocations in adults. A brachial artery injury from trauma could cause it, but that's not the most common in children. Also, maybe a humeral shaft fracture, but those are less common in kids compared to supracondylar fractures.
Clinical pearl: Remember that Volkmann's contracture is a feared complication of supracondylar humerus fractures in children. Early recognition of compartment syndrome with symptoms like pain on passive stretch, pallor, pulselessness, and paralysis is crucial. Immediate decompression is needed to prevent contracture.
Putting it all together, the correct answer is the supracondylar humerus fracture. The explanation should highlight the mechanism, why other options are less likely, and the key clinical point to remember for exams.
**Core Concept**
Volkmann's ischaemic contracture results from **acute compartment syndrome** in the forearm, caused by prolonged ischaemia of the anterior interosseous compartment. This leads to **muscle necrosis** and fibrosis, causing a fixed flexion of the fingers and wrist (claw hand). In children, it is most commonly triggered by **supracondylar humerus fractures** due to brachial artery injury or compartment pressure elevation.
**Why the Correct Answer is Right**
**Supracondylar humerus fractures** in children (commonly due to falls on an outstretched hand) are the leading cause. The fracture can compress the brachial artery or