Pain at the top of the pelvic bone, specifically along the prominent, curved ridge known as the iliac crest, is a common complaint. This bony structure forms the largest part of the pelvis and serves as a major anchor point for numerous muscles, ligaments, and fascia that support the torso and facilitate hip and leg movement. Because the iliac crest is a central hub of biomechanical forces, pain in this area rarely stems from the bone itself. Instead, discomfort usually originates from the surrounding soft tissues and adjacent joints, involving muscle inflammation, structural alignment problems, or nerve irritation.
Strains and Soft Tissue Inflammation
The majority of discomfort felt along the iliac crest originates from the soft tissues that attach directly to its surface, primarily due to overuse or sudden mechanical stress. Over-exertion or repetitive movements in sports or daily activities can lead to inflammation and micro-tears in the tendons and muscles that pull on the bone. This condition is often described as a deep ache or tenderness directly upon palpation of the bony ridge.
Several major muscle groups insert here, making them susceptible to strain and tendinitis. The oblique abdominal muscles, which are responsible for twisting and side-bending the trunk, attach along the outer edge of the crest. A forceful rotation or an intense core workout can cause an abdominal muscle strain that manifests as pain along the anterior, or front, aspect of the pelvic bone. Similarly, the powerful gluteal muscles, particularly the gluteus medius and minimus, attach just below the crest. Repetitive motion, especially during walking and running, can lead to tendinopathy in these stabilizing muscles, felt as pain near the posterior, or back, portion of the crest.
Another localized source of inflammatory pain is the iliolumbar ligament, a strong band of connective tissue that stabilizes the lowest vertebrae of the spine (L4 and L5) to the inner surface of the iliac crest. Inflammation or a tear in this ligament, sometimes called iliolumbar syndrome, can cause localized tenderness and pain often confused with other lower back issues. This pain is aggravated by movements that involve bending, twisting, or rotating the trunk, as these actions place tension on the ligament’s attachment point. The hip flexor muscles, which are necessary for lifting the knees, also have attachments near the iliac crest. Tendinitis in these flexors can refer pain to the front of the pelvic bone, especially during activities like climbing stairs or running.
Joint Instability and Alignment Problems
Pain felt at the top of the pelvic bone can be a result of dysfunction in the adjacent sacroiliac (SI) joint. This joint connects the sacrum, a triangular bone at the base of the spine, to the ilium, the largest part of the pelvis. Although the SI joint is located lower and more posterior than the iliac crest, pain originating from its inflammation or instability often radiates upward and is perceived as being near the top of the bone.
Sacroiliac joint dysfunction (SIJD) occurs when there is either too much movement (hypermobility) or too little movement (hypomobility) within the joint. Hypermobility can cause instability, leading to inflammation and pain that often radiates into the buttock, groin, and occasionally upward toward the crest. Hypomobility, where the joint becomes stiff, can also cause localized pain due to the uneven distribution of forces across the joint surfaces. SIJD can mimic sciatica, with pain extending down the leg, though it usually remains above the knee.
Conditions such as pregnancy, trauma, or degenerative changes like arthritis can contribute to SIJD by altering the joint’s mechanics and ligamentous integrity. Hormonal changes during pregnancy can loosen the pelvic ligaments, temporarily increasing SI joint instability. Trauma, such as a fall onto the buttock or a car accident, can also directly stress the joint, leading to chronic inflammation and referred pain. A physical examination often reveals tenderness when pressure is applied directly over the SI joint.
Neurological Causes and Referred Pain
Pain near the iliac crest may be caused by irritation or compression of a nerve, leading to sensations felt far from the nerve’s actual entrapment point. One specific condition affecting the area near the front of the iliac crest is Meralgia Paresthetica (MP), which involves the lateral femoral cutaneous nerve (LFCN). This purely sensory nerve travels from the spine, across the pelvis, and often passes through a narrow tunnel near the anterior superior iliac spine (ASIS).
Compression of the LFCN can cause distinct symptoms in the outer and front portion of the thigh, including burning pain, numbness, tingling, or altered sensation. The nerve is vulnerable to pressure from tight clothing, such as heavy utility belts or restrictive waistbands, or from increased abdominal pressure due to weight gain or pregnancy. Although the primary symptoms are felt in the thigh, the compression site is adjacent to the iliac crest, which can lead to the misperception that the pain originates from the pelvic bone itself.
Pain can also be referred from the lumbar spine, specifically from disc issues or nerve root irritation higher up in the back. A herniated disc or spinal stenosis can compress a nerve root, causing pain that travels along the nerve path. While classic sciatica follows a path down the leg, some nerve compression issues in the upper lumbar spine can result in pain perceived in the hip or gluteal region, sometimes radiating up toward the iliac crest. This referred pain is often accompanied by other neurological signs, such as weakness or changes in reflexes, helping to distinguish it from localized muscle strain.
Recognizing Serious Symptoms
While most pain at the top of the pelvic bone relates to musculoskeletal causes that resolve with conservative treatment, certain symptoms warrant immediate medical evaluation. Any sudden, severe pain following a significant traumatic event, such as a car accident or a high fall, requires prompt attention to rule out a pelvic fracture. Although rare, a fracture of the iliac crest can occur from direct, forceful impact.
Pain accompanied by systemic symptoms should be investigated without delay, as these may indicate an underlying infection or other serious condition. These symptoms include:
- Unexplained fever or chills, which can suggest a bone infection (osteomyelitis) or a deep abscess.
- Unexplained, unintentional weight loss, or pain that persists or worsens significantly at night.
- Progressive neurological symptoms, such as rapidly worsening leg weakness or foot drop.
- New difficulty controlling bowel or bladder function, which signals potential severe nerve compression in the spine.