Potential Causes of Constant Pressure and Tailbone Pain
Constant pressure and tailbone pain (coccydynia) is most commonly caused by abnormal coccygeal mobility (hypermobility or rigidity), traumatic injury, or coccygeal spicules (bony projections), with approximately 70% of cases showing abnormal motion on dynamic imaging. 1, 2
Primary Coccygeal Causes
Mechanical/Structural Abnormalities
- Abnormal coccygeal mobility (most common - 70% of cases): Includes hypermobility, anterior/posterior subluxation or luxation of the coccyx, visible on dynamic radiographs (standing vs. sitting lateral X-rays) 2
- Traumatic injuries: Fracture, subluxation, or luxation of the coccyx 2
- Coccygeal spicules: Bony excrescences that can irritate surrounding tissues 1, 2
- Disc degeneration: At sacrococcygeal (SC) and intercoccygeal (IC) segments 2
- Post-obstetric trauma: Childbirth-related injury to the coccyx 1
Infectious/Neoplastic Causes
- Osteomyelitis of the coccyx 2
- Tumors: Both primary and metastatic lesions in the coccygeal region 1, 2
- Vertebral coccidioidomycosis: In endemic areas, fungal infection can cause vertebral pain and instability 3
Secondary (Extracoccygeal) Causes
Local Soft Tissue Pathology
- Pilonidal cyst 2
- Perianal abscess 2
- Hemorrhoids 2
- Pelvic floor muscle spasm: Particularly levator ani muscle tension 2, 4
Referred Pain Sources
- Lumbosacral spine disorders: Including disc herniation 2, 4
- Sacroiliac joint dysfunction 2
- Piriformis muscle disorders 2
- Pelvic organ diseases: Disorders of rectum, sigmoid colon, and urogenital system 4
- Arachnoiditis of lower sacral nerve roots 5
Functional/Chronic Pain Syndromes
- Centrally mediated abdominal pain syndrome (CAPS): When pain persists beyond tissue healing and becomes centrally sensitized 6
- Idiopathic coccydynia: Approximately 30% of cases have no identifiable cause 2
Key Diagnostic Considerations
The diagnosis is primarily clinical but requires imaging to exclude serious pathology. Look for:
- Pain provoked specifically by sitting and rising (pathognomonic feature) 1, 4
- Traumatic history (fall, childbirth, chronic overload from obesity, prolonged sitting, cycling, rowing) 1, 2
- Point tenderness on manual examination of the coccyx (digital rectal exam) 4
- Absence of sitting-related pain suggests neurological causes like lumbar disc herniation rather than true coccydynia 4
Essential Imaging Workup
- Dynamic lateral radiographs (standing and sitting positions) - reference standard for detecting abnormal mobility 1, 2
- MRI - necessary to exclude tumors, infections, and evaluate soft tissue structures 1, 7
- Coccygeal ultrasound with dynamic maneuver - emerging alternative but not yet fully validated 1
Common Pitfall
Do not assume all tailbone pain is mechanical coccydynia. If pain is not specifically worsened by sitting/rising and manual examination doesn't reproduce symptoms, investigate neurological causes (lumbar pathology) and visceral sources (pelvic organs, rectum) 4. In 30% of cases, no cause is found despite thorough evaluation 2.
The pathophysiology often involves chronic static and dynamic overload leading to ligamentous injury, disc degeneration, and eventual abnormal motion at the sacrococcygeal junction 2. When conservative measures fail, diagnostic injections of local anesthetic into suspected pain generators (SC disc, first IC disc, Walther's ganglion, muscle attachments) can confirm coccygeal origin 2.