Final answer:
The most likely diagnosis of a knee injury characterized by a popping sound followed by an inability to perform a straight leg raise is a patellar tendon rupture.
Step-by-step explanation:
In the context of an injury that is accompanied by a popping sound and a subsequent inability to extend the knee for a straight leg raise, the likely diagnosis is a patellar tendon rupture. This type of injury often presents with an audible pop at the time of injury, followed by a significant difficulty or inability to straighten the knee, which is indicative of the crucial role the patellar tendon plays in knee extension.
The other listed options, such as meniscal tear, anterior cruciate ligament (ACL) tear, and quadriceps strain, despite being common knee injuries, may not always present with an immediate inability to perform a straight leg raise, a key feature associated with a patellar tendon rupture.
The likely diagnosis in the given scenario is an Anterior Cruciate Ligament (ACL) tear.
An ACL tear is often caused by a forceful blow to the anterior knee, producing hyperextension. The ACL supports the knee when it is flexed and weight-bearing, and when it tears, it can result in a popping sound and subsequent inability to extend the knee for a straight leg raise.
Therefore, the most likely diagnosis in this case is a Anterior Cruciate Ligament (ACL) tear.