COMLEX USA Practice Exam 2025 – The All-in-One Guide to Master the Comprehensive Osteopathic Medical Licensing Exam

The L4-L5 level is indeed recognized as the most common site for herniated discs in the lumbar spine. This region experiences significant mechanical stress due to the lumbar spine's role in weight-bearing and movement. The intervertebral disc at this level is particularly susceptible to degeneration and injury, often due to factors such as repetitive stress, poor posture, or aging.

At the L4-L5 disc space, the disc's posterior annulus fibrosus can weaken, leading to the nucleus pulposus herniating posteriorly or laterally and potentially compressing nearby spinal nerves. This can result in radicular pain, numbness, or weakness in the lower limbs, characteristic signs of lumbar disc herniation.

While other levels like L5-S1 also see a significant number of herniations, especially in specific populations or in those with particular activities, the L4-L5 level remains the most frequently affected site, making it the correct answer in this context.