In the case of a posterior knee dislocation, which study is considered mandatory?

In the context of a posterior knee dislocation, angiography is considered a mandatory study due to the high risk of vascular injury associated with this type of dislocation. The popliteal artery runs behind the knee joint and is susceptible to damage when a dislocation occurs. Given the potential for severe complications, including limb ischemia, it is crucial to assess for any arterial injury. Angiography allows for direct visualization of the blood vessels supplying the lower leg and can help identify any vascular compromise. This timely evaluation is vital for determining the appropriate management and ensuring the preservation of limb function.

Other imaging modalities, such as plain films or specific views of the knee, may help evaluate for associated fractures or confirm the dislocation but do not provide the necessary information regarding arterial integrity. Measuring compartment pressures can be important in cases of compartment syndrome, which may arise from a dislocation, but it does not address the immediate concern of vascular injury that can have life-threatening implications.