Differential Diagnosis for Right Lower Back Pain Outer, Not on Spine

Single Most Likely Diagnosis

• Musculoskeletal strain: This is often the most common cause of lower back pain, especially when it's localized to one side and not directly on the spine. Activities that involve lifting, bending, or sudden movements can lead to strain in the muscles or ligaments of the lower back.

Other Likely Diagnoses

• Trochanteric bursitis: Inflammation of the bursa over the trochanter (the bony prominence at the top of the femur) can cause pain on the outer aspect of the hip and lower back. This condition is more common in women and can be exacerbated by activities that involve running, cycling, or prolonged standing.
• Piriformis syndrome: The piriformis muscle runs from the base of the spine to the thighbone, and when it compresses or irritates the sciatic nerve, it can cause pain in the lower back that radiates down the back of the leg. This condition is often associated with activities that involve sitting for long periods.
• Lumbar facet joint pain: The facet joints are small stabilizing joints located between and behind adjacent vertebrae. Pain from these joints can be referred to the lower back and buttocks area, often on one side.

Do Not Miss Diagnoses

• Appendicitis: Although appendicitis typically presents with abdominal pain, in some cases, especially if the appendix is retrocecal (located behind the cecum), the pain can be referred to the lower back. Missing this diagnosis can lead to severe consequences, including perforation and peritonitis.
• Kidney stones or pyelonephritis: Pain from kidney stones or infection (pyelonephritis) can sometimes be felt in the lower back, often on one side. These conditions require prompt medical attention to prevent complications such as sepsis or kidney damage.
• Ovarian cyst or torsion: In women, a ruptured ovarian cyst or ovarian torsion can cause severe lower abdominal or back pain. These are medical emergencies that require immediate attention.

Rare Diagnoses

• Spinal osteomyelitis or discitis: Infections of the spine, such as osteomyelitis (infection of the bone) or discitis (infection of the intervertebral disc), can cause back pain. These conditions are less common but can have serious consequences if not treated properly.
• Tumor: Although rare, tumors (either primary or metastatic) can cause back pain by compressing or destroying spinal structures. A thorough evaluation is necessary to rule out such conditions, especially in patients with risk factors or unexplained weight loss.