S1 Radiculopathy Initially Presenting With Sole Knee Flexion Weakness: A Case Report.

Lumbar disc herniation can lead to low back pain and/or sciatica, as well as manifest with neurological symptoms in specific dermatomal/myotomal patterns due to nerve root irritation. S1 radiculopathy is the result of L5-S1 disc herniation and is usually presented with foot plantar flexion/eversion weakness and hypoesthesia in the lateral aspect of the foot. We present a case of S1 radiculopathy that initially presented with hamstring weakness and posterior knee pain as the only manifestations, leading to a delay in the initial diagnosis and treatment. To the best of our knowledge, no previous studies have reported this atypical presentation that resulted from S1 radiculopathy. This case report is of great clinical value, as it will help diagnosticians broaden the diagnostic range in patients with similar symptomatology and avoid diagnostical pitfalls.