Enthesopathy of the Iliac Wing
Enthesopathy of the iliac wing is pathology occurring at the attachment sites where muscles, tendons, ligaments, or fascia insert into the iliac bone, manifesting as inflammation, degeneration, or calcification at these insertion points. 1
Definition and Anatomical Context
Enthesopathy refers to disease processes occurring at "entheses"—the specific anatomical sites where tendons, ligaments, joint capsules, fascia, or muscle attachments insert into bone 1, 2. The iliac wing (iliac crest) represents one of the common anatomical locations where enthesopathy develops 2.
Pathophysiologic Categories
Enthesopathy at the iliac wing can result from multiple distinct mechanisms 1, 2:
- Inflammatory enthesopathy (enthesitis): Characteristic of seronegative spondyloarthropathies, representing active inflammation at the insertion site 1
- Degenerative enthesopathy: Age-related changes that increase in frequency with aging, plateauing after age 60 3
- Traumatic enthesopathy: Post-injury changes including tendon avulsion or rupture sequelae 4
- Metabolic/endocrine enthesopathy: Associated with systemic metabolic or endocrine disorders 1, 5
- Occupational enthesopathy: Related to repetitive mechanical stress 1
Clinical Presentation
Pain originating from the iliac crest entheses (enthesalgia) represents a potential cause of chronic musculoskeletal pain 5. The clinical significance varies based on the underlying etiology and patient age 3.
Key Clinical Considerations
- In patients under age 60, iliac crest enthesophytes are usually unrelated to any underlying systemic disorder 3
- Mechanical factors appear to outweigh inflammatory processes in determining enthesophyte formation at most sites 3
- Patients with rheumatoid arthritis manifest less severe iliac crest enthesial reactions compared to other populations 3
Radiographic Features
Specific imaging findings at the iliac wing include 2:
- Bone erosion at the attachment site
- Hyperostosis (excessive bone formation)
- Fragmentation of the entheseal bone
- Calcific overgrowth (enthesophytes)
- Crystal deposition in certain metabolic conditions
Diagnostic Approach
Ultrasound with high-frequency transducers is the simple, cost-effective, and feasible first-line test to detect iliac wing enthesopathy 1. This modality can identify pathology at entheses that may not be clinically obvious on physical examination alone.
Treatment Implications
Iliac wing enthesopathy is amenable to specific interventions 1:
- Local corticosteroid injections for inflammatory enthesopathy
- Physiotherapy to address mechanical factors
- Non-steroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation control
- Treatment of the primary underlying disease when systemic conditions are present
Critical Pitfall
Unrecognized and untreated enthesopathy can lead to considerable morbidity 1. Clinicians must maintain suspicion for enthesopathic involvement when patients present with chronic iliac crest pain, particularly in the context of spondyloarthropathies or after trauma.