What could be causing my coccydynia (tailbone pain) and buttock pain without any reported trauma or injury?

Coccydynia and Buttock Pain Without Trauma

For tailbone and buttock pain without injury, the most common cause is abnormal coccyx mobility (hypermobility or subluxation), found in 70% of cases, though 30% remain idiopathic even after thorough evaluation. 1

Primary Diagnostic Considerations

Coccygeal Pathology (Most Common)

• Abnormal coccyx mobility is the leading cause, including hypermobility, anterior/posterior subluxation, or luxation at the sacrococcygeal and intercoccygeal segments 1
• Chronic static and dynamic overload from obesity, prolonged sitting, bicycling, rowing, or riding can cause these changes even without acute trauma 1
• Disc degeneration at sacrococcygeal and intercoccygeal segments, coccygeal spicules (bony excrescences), and idiopathic causes (30% of cases) are other possibilities 1

Pelvic Floor Dysfunction (Highly Associated)

• Nearly 50% of women with pelvic pain have coexisting coccygodynia, with significantly higher rates of muscle spasm (50.8%), outlet dysfunction constipation (31.7%), and fibromyalgia (15.9%) 2
• Physical examination findings include sacrococcygeal joint hypomobility (65.1%), coccygeus muscle spasm (77.8%), anococcygeal ligament pain (63.5%), and impaired pelvic floor muscle coordination (77.8%) 2

Neural Causes

• Deep gluteal syndrome with sciatic nerve entrapment in the subgluteal space can cause chronic buttock pain and pseudo-sciatica 3
• Cluneal nerve entrapment at the iliac crest may produce buttock pain mimicking sciatica 3
• Pudendal nerve, gluteal nerves, and posterior cutaneous nerve of thigh entrapment are less common but possible 3

Hip-Related Pain

• Hip pathology including femoroacetabular impingement (FAI) syndrome and acetabular dysplasia can present with buttock pain, though groin pain is more typical 4
• Pain may radiate to back, buttock, or thigh even when the primary pathology is in the hip joint 4

Essential Diagnostic Workup

Imaging Studies

• Dynamic radiographs (lateral X-rays in standing AND sitting positions) are essential to detect abnormal coccyx mobility, the most common pathological finding 1
• MRI and ultrasound can identify sciatic neuritis, peri-sciatic pathology, neural compression, and peri-neural adhesions or fibrosis in deep gluteal syndrome 3
• Standard radiographs may miss dynamic instability that only appears with positional changes 5

Physical Examination Specifics

• Palpate the coccyx externally and perform rectal examination to assess sacrococcygeal joint mobility, coccygeus muscle spasm, and anococcygeal ligament tenderness 2
• Assess for hip pathology with internal rotation testing, which reproduces symptoms in hip-related pain 4
• Evaluate for neurogenic causes by checking straight-leg raise, motor strength (L4-S1 nerve roots), reflexes, and sensory distribution 4
• Screen for pelvic floor dysfunction, particularly in women, as this strongly correlates with coccygodynia 2

Diagnostic Injections

• Local anesthetic injections into sacrococcygeal disc, first intercoccygeal disc, Walther's ganglion, or muscle attachments can confirm coccygeal origin of pain 1

Conditions to Exclude

Red Flags Requiring Urgent Evaluation

• Pilonidal cyst, perianal abscess, hemorrhoids, and pelvic organ diseases must be excluded 1
• Lumbosacral spine pathology, sacroiliac joint dysfunction, and piriformis syndrome can mimic coccygodynia 1
• In patients with alternating buttock pain, morning stiffness improving with exercise, and awakening with back pain in the second half of the night, consider ankylosing spondylitis 4

Vascular Causes

• Iliac artery occlusive disease produces hip, buttock, and thigh pain during exercise that relieves with rest 6
• Check femoral, popliteal, posterior tibial, and dorsalis pedis pulses; obtain ankle-brachial index if vascular claudication is suspected 6

Treatment Algorithm

Conservative Management (First-Line)

• Rest, NSAIDs, coccyx cushion, and physical therapy including manual therapy (massage and stretching of levator ani muscle, coccyx mobilization) 1
• Acupuncture may provide benefit 1

Interventional Procedures (Second-Line)

• Ultrasound-guided radiofrequency ablation (RFA) with steroid injection of the coccygeal nerve shows 54% of patients achieving >50% pain reduction at 12 weeks, with 66% achieving >50% improvement in function scores 7
• Local anesthetic and corticosteroid injections into painful structures provide relief in many patients 1
• RFA at 90°C for 60 seconds followed by dexamethasone and bupivacaine injection is effective and has lower adverse event rates 7

Surgical Management (Last Resort)

• Partial or total coccygectomy is indicated only in refractory cases, particularly in patients with abnormal coccyx mobility and spicules who respond best to surgical treatment 1
• Surgery should be reserved for patients who fail conservative and interventional therapies 1

Critical Pitfalls to Avoid

• Do not rely on static radiographs alone—dynamic imaging (sitting versus standing) is essential to detect abnormal mobility in 70% of cases 1
• Do not overlook pelvic floor dysfunction, especially in women, as it coexists in nearly half of patients with pelvic pain and requires specific physical therapy 2
• Do not assume all buttock pain is lumbar spine-related—neural entrapment in the subgluteal space (deep gluteal syndrome) is a significant cause of chronic symptoms lasting >6 months 3
• Do not dismiss idiopathic coccygodynia—30% of cases have no identifiable cause even after thorough evaluation, but these patients still benefit from conservative and interventional treatments 1