What are the possible causes of lower back, hip, and iliac crest pain that is sharp with movement and worsened by sitting or lying down?

Differential Diagnosis: Lower Back, Hip, and Iliac Crest Pain

The most likely diagnosis is iliac crest pain syndrome (ICPS), also known as iliolumbar syndrome or thoracolumbar junction syndrome (Maigne's syndrome), which presents with the exact constellation of symptoms described and occurs in 33-58% of patients with low back pain depending on the clinical setting 1.

Primary Diagnostic Considerations

Iliac Crest Pain Syndrome (Most Likely)

• ICPS is characterized by localized tenderness over the medial part of the iliac crest, typically 7-8 cm from the midline 1, 2.
• This syndrome presents with sharp pain reproduced by lumbar spine movements (64% of cases), hip movements (53%), leg raising (37%), and localized pain in 73% of patients 1.
• The pain originates from either:
  • Cutaneous dorsal ramus entrapment from L1 or L2 nerve roots crossing the iliac crest, which is more anatomically accessible to palpation than the iliolumbar ligament itself 2.
  • Iliolumbar ligament syndrome caused by tensioning through repeated anteflexion and contralateral lateroflexion-rotation movements 3.
• Pain worsened by sitting and lying down is consistent with this diagnosis, as these positions maintain tension on the affected structures 4.

Thoracolumbar Junction Syndrome (Maigne's Syndrome)

• This represents a painful segmental vertebral dysfunction at D12/L1 leading to referred pain at the posterior iliac crest 3, 5.
• Diagnosis requires rigorous segmental spinal examination with palpation for texture changes in skin, muscle, and teno-periosteal tissues 3.
• Pain can be demonstrated by applying pressure on the facet joints or to the sides of the spinous processes at the thoracolumbar junction 5.
• Radiological studies typically show only mild degenerative changes 5.

L5/S1 Facet Syndrome

• Characterized by more medial lumbosacral pain that is accentuated on facet palpation 3.
• Pain is reproduced on combined heterolateral extension-rotation of the spine 3.
• This is less likely given the specific iliac crest localization described.

Clinical Examination Approach

Key examination findings to confirm ICPS:

• Palpate the medial iliac crest 7-8 cm from midline for exquisite tenderness 1, 2.
• Test lumbar spine movements (flexion, extension, rotation) to reproduce pain 1.
• Perform hip movements to assess for pain reproduction (53% positive) 1.
• Conduct straight leg raising test (positive in 37%) 1.
• Perform heel-fall test (positive in 24%) 1.

For thoracolumbar junction syndrome:

• Apply pressure to facet joints at T12-L2 level 5.
• Palpate spinous processes at the thoracolumbar junction 5.

Diagnostic Imaging Strategy

Initial imaging should follow ACR Appropriateness Criteria for low back pain:

• Imaging is NOT indicated initially for uncomplicated acute low back pain without red flags 6.
• Consider imaging only after 4-6 weeks of conservative management with minimal improvement 6.
• Plain radiographs of the pelvis and hip should be the first test if imaging is pursued 7.
• MRI without contrast is appropriate if radiographs are negative or equivocal and soft tissue pathology is suspected 7.

Red flags requiring immediate imaging include:

• Cauda equina syndrome symptoms 6.
• Suspected malignancy, fracture, or infection 6.

Treatment Algorithm

First-line treatment (before imaging):

• Manual therapy centered on the dorsolumbar or lumbosacral hinge is recommended as first-line treatment 3.
• Rehabilitation of motor control of deep stabilizing muscles of the dorsolumbar spine is essential 3.
• Temporary diagnostic/therapeutic infiltration of the posterior iliac crest with lidocaine can confirm diagnosis and provide relief 4.

Second-line interventions:

• Epidural blocks and sympathetic nerve blocks have shown efficacy 5.
• Local infiltrations often complete the physiotherapy approach 3.

Critical Pitfalls to Avoid

• Do not confuse ICPS with root irritation syndrome, as this may lead to unnecessary surgery 4.
• The iliac insertion of the iliolumbar ligament is actually inaccessible to palpation, being shielded by the iliac crest—the pain is more likely from dorsal rami nerve entrapment 2.
• Chronic iliolumbar syndrome is a frequent cause of permanent low back disability that is commonly underrecognized 4.
• ICPS occurs in approximately 41% of all patients with low back pain across different clinical settings, making it far more common than typically appreciated 1.