L4L5

L4L5 refers to the lumbar vertebral level between the fourth (L4) and fifth (L5) lumbar vertebrae. This region is in the lower back and contains the intervertebral disc between L4 and L5, as well as the facet joints that contribute to stability and movement of the lumbar spine. The L4-L5 disc is one of the largest in the lumbar region and bears a significant portion of axial load, particularly during dynamic activities.

The L4-L5 level is a common site for degenerative changes and pathology. Degenerative disc disease, facet joint arthropathy, and spondylolisthesis can occur here. It is also one of the most frequent levels for lumbar disc herniation, with herniation at this level commonly affecting the L5 nerve root. Typical clinical features include lower back pain with radiation to the buttock or leg, sensory changes over the dorsum of the foot, and weakness in the muscles that control ankle and toe movements. In some cases, a large central herniation can contribute to cauda equina syndrome, a medical emergency.

Diagnosis generally begins with magnetic resonance imaging (MRI), which best shows soft tissue structures such as discs and nerve roots. X-rays assess alignment and stability, while computed tomography (CT) may be used when MRI is contraindicated or to better characterize bony anatomy. Management ranges from conservative measures—physical therapy, nonsteroidal anti-inflammatory drugs (NSAIDs), and activity modification—to interventional procedures such as epidural steroid injections. Surgical options include microdiscectomy or decompression for persistent radicular symptoms, and fusion or disc replacement in cases of instability or severe degenerative disease at L4-L5. The choice of treatment depends on symptom severity, neurologic function, and imaging findings.