A 47-year-old man awakens with low back pain after a weekend of gardening. He recalls no specific incident of trauma and has never had back pain before. There is no radiation of the pain and no disturbance of normal bowel or bladder function. The ROM of the low back is painful and restricted in all planes, and there is paraspinal tenderness from L2 to L5 on the right. Scoliosis and kyphosis are absent. Findings on straight-leg-raising test are negative, reflexes are active and equal, and the patient can walk on his heels and toes. Findings on x-rays of the lumbar spine are normal. Which is the best treatment?

**Core Concept**
The patient presents with acute onset of low back pain without any specific incident of trauma, radiation of pain, or neurological deficits. This scenario is suggestive of acute mechanical low back pain, which is often caused by strain or overuse of the back muscles or ligaments.

**Why the Correct Answer is Right**
The patient's presentation is consistent with acute mechanical low back pain, which is typically caused by muscle strain or overuse. The x-rays of the lumbar spine are normal, ruling out any structural abnormalities such as herniated discs or spondylolisthesis. The patient's ability to walk on his heels and toes and the absence of neurological deficits further support the diagnosis of mechanical low back pain. The best treatment for acute mechanical low back pain is initially conservative management with rest, ice, compression, and elevation (RICE), as well as nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because surgery is not typically indicated for acute mechanical low back pain, especially without any structural abnormalities or neurological deficits.

**Option B:**
This option is incorrect because physical therapy may be beneficial for chronic low back pain or mechanical low back pain that persists beyond 4-6 weeks, but is not the initial treatment of choice for acute mechanical low back pain.

**Option C:**
This option is incorrect because muscle relaxants may be used to treat muscle spasms associated with acute mechanical low back pain, but are not the primary treatment for this condition.

**Option D:**
This option is incorrect because epidural injections may be used to treat chronic low back pain or radiculopathy, but are not the initial treatment of choice for acute mechanical low back pain.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the initial treatment for acute mechanical low back pain should focus on conservative management, including RICE, NSAIDs, and rest, rather than immediate referral to physical therapy or surgery. This approach helps to reduce pain and inflammation, allowing the patient to recover from the acute injury.

**Correct Answer: C. Muscle relaxants may be used to treat muscle spasms associated with acute mechanical low back pain.**

✓ Correct Answer: A. Bed rest for 48 hours, anti-inflammatory agents, heat to the low back, and nonnarcotic analgesics