Tailbone Injury | Coccydynia
- Mechanism: Direct fall onto buttocks (sitting position). Childbirth. Repetitive trauma.
- Diagnosis: Clinical history and examination. X-ray confirms fracture/dislocation.
- Treatment: Conservative in vast majority. Cushion, NSAIDs, PT.
- Coccydynia: Persistent coccygeal pain. May require injections or, rarely, coccygectomy.
- Prognosis: Most resolve in 4-12 weeks. Small subset develop chronic pain.
- “Most coccyx fractures are managed conservatively.
- “5F: Female, Fat, Forty, Fall, Fracture (risk factors for coccyx injury/coccydynia).
- “Dynamic lateral X-ray (Sitting vs Standing) can assess mobility.
- “Coccygectomy is reserved for refractory coccydynia.
Fall Assessment. A fall onto buttocks can also cause sacral fractures, vertebral compression fractures. Complete assessment.
Coccydynia. 10-20% develop chronic pain. Warn patients. May need injections or surgery.
Limited Utility. X-ray often not needed if history is clear. Clinical diagnosis.
Coccygectomy. Reserved for truly refractory cases after 6-12 months of failed conservative treatment.
- Details
- Direct fall onto buttocks, Childbirth
- Details
- Tailbone (Sacrococcygeal junction)
- Details
- Clinical +/- X-ray
- Details
- Cushion, NSAIDs, Time
- Details
- Coccydynia (10-20%)
5F5 F's of Coccydynia
Hook:Risk factors for coccyx problems.
CRANKConservative Treatment
Hook:Conservative coccyx care.
Sit vs StandDynamic X-ray
Hook:Assess coccygeal mobility.
Overview and Epidemiology
Coccyx fractures and coccydynia (coccyx pain) result from trauma to the tailbone (coccyx). The coccyx is the terminal segment of the spine, formed by 3-5 fused vertebrae.
- Sex: 5x more common in females (shorter, more curved coccyx).
- Age: Peak 40-50 years.
- Risk Factors: Obesity, Female, Direct trauma, Childbirth.
- Direct Fall: Sitting position. Most common.
- Childbirth: Traumatic delivery. Coccyx can sublux or fracture.
- Repetitive Trauma: Cycling, Rowing.
- Idiopathic Coccydynia: Pain without clear trauma (often postural/degenerative).
Anatomy and Pathophysiology
- Coccyx: 3-5 fused vertebral segments. Articulates with sacrum at Sacrococcygeal Joint.
- Attachments: Gluteus Maximus, Coccygeus, Levator Ani, Anococcygeal Ligament.
- Mobility: Normally has some flexion/extension at sacrococcygeal joint.
- Acute Injury: Direct impact causes fracture or dislocation of coccyx.
- Inflammation: Local swelling and pain.
- Healing: Most heal with fibrous union over weeks to months.
- Chronic Coccydynia: Persistent pain due to:
- Malunion with abnormal angulation.
- Hypermobility or instability at sacrococcygeal joint.
- Degenerative changes.
- Referred pain (L5/S1, Sacroiliac).
Classification
Injury Types
- Fracture: Break in coccygeal segment.
- Dislocation: Displacement at sacrococcygeal or intercoccygeal joint.
- Fracture-Dislocation: Combined.
Distinction rarely changes management.
Clinical Assessment
- Mechanism: Fall? Childbirth? Gradual onset?
- Pain: Worse with sitting (especially on hard surfaces), Leaning back, Defecation.
- Duration: Acute vs Chronic.
- Inspection: Bruising over sacrococcygeal area.
- Palpation: Point tenderness over coccyx (external). Tenderness on bimanual palpation (PR/PV combined with external).
- Coccygeal Mobility: Assess with PR exam. Pain with manipulation?
- Neurological Exam: Usually normal (coccyx does not contain cord).
- Rectal Exam: Exclude rectal pathology.
Investigations
- Clinical Diagnosis: If history is clear (fall, tailbone pain), imaging may not change management.
- Lateral X-ray (Coccyx): Shows fracture, dislocation, angulation.
- Dynamic Lateral X-rays: Sitting vs Standing. Assess mobility (greater than 25 degrees = Hypermobility).
- MRI: Rarely needed. For persistent pain (exclude tumor, infection).
- Sacral fracture (if significant trauma).
- Pilonidal disease.
- Rectal pathology.
Differential Diagnosis
Pain localised to the tailbone is not always coccygeal in origin. The most important task is to separate true coccydynia from referred or sinister pathology before committing to long-term coccyx-directed treatment.
- Distinguishing Features
- Pain worse sitting and on standing up; point tenderness over coccyx; trauma or childbirth history
- Key Discriminator
- Reproduced by direct coccygeal palpation +/- dynamic radiograph lesion
- Distinguishing Features
- Older osteoporotic patient or athlete; tenderness over sacrum not coccyx
- Key Discriminator
- MRI marrow oedema; H-shaped uptake on bone scan (Honda sign)
- Distinguishing Features
- Midline natal-cleft sinus/pits, discharge, abscess; soft-tissue not bony pain
- Key Discriminator
- Visible sinus openings and induration in natal cleft
- Distinguishing Features
- Abscess, fissure, proctalgia fugax; pain with defecation, anal not coccygeal tenderness
- Key Discriminator
- PR exam and anoscopy; no bony coccygeal tenderness
- Distinguishing Features
- Radicular leg symptoms, positive SIJ provocation; coccyx non-tender
- Key Discriminator
- Normal coccygeal palpation; positive root/SIJ tests
- Distinguishing Features
- Insidious unrelenting pain, night pain, neurological signs, mass on PR
- Key Discriminator
- MRI mass; do not attribute persistent atypical pain to benign coccydynia
Persistent atypical coccygeal pain without clear trauma, night pain, a palpable presacral mass on rectal examination, or neurological signs mandate MRI to exclude chordoma or other sacrococcygeal tumour before labelling pain as benign coccydynia.
Management Algorithm
Conservative (Standard)
- Cushion: Donut or wedge cushion. Reduces pressure on coccyx when sitting.
- Analgesia: NSAIDs (first line). Paracetamol. Opioids rarely needed.
- Stool Softeners: Reduce straining during bowel movements.
- Activity Modification: Avoid prolonged sitting on hard surfaces.
- Physiotherapy: Pelvic floor exercises. Manual therapy.
- Time: Most resolve in 4-12 weeks.
90% resolve with conservative care.
Surgical Technique
Coccygectomy Technique
- Position: Prone (jack-knife or flat).
- Prophylaxis: Antibiotics. Bowel prep not usually needed.
- Incision: Midline longitudinal over coccyx.
- Dissection: Incise periosteum. Dissect subperiosteally. Identify sacrococcygeal joint.
- Excision: Divide at sacrococcygeal joint (or leave most proximal segment). Remove coccyx.
- Closure: Close periosteum if possible. Layered closure. Avoid dead space.
- Post-op: Wound care. Avoid sitting directly on wound.
Standard midline approach with careful subperiosteal dissection.
Complications
- Risk Factor
- Severe injury / Malunion
- Management
- Injections / Coccygectomy
- Risk Factor
- Proximity to anus
- Management
- Antibiotics / Washout
- Risk Factor
- Dissection error
- Management
- Primary repair
- Risk Factor
- Inadequate hemostasis
- Management
- Drainage
- Risk Factor
- Nerve irritation
- Management
- Reassurance / Injections
Postoperative Care
After Coccygectomy:
- Wound care (close to anus - risk of infection).
- Avoid direct sitting on wound for 2-4 weeks (cushion).
- Antibiotics if infection concern.
- Stool softeners.
- Return to normal activity: 4-6 weeks.
Outcomes
- Conservative: 90% resolve in weeks to months.
- Coccygectomy: 70-90% significant improvement in refractory cases.
- Chronic Coccydynia: Minority have persistent issues.
Coccygeal Morphology and the Sacrococcygeal Joint
The topic notes a 'curved coccyx' and 'some mobility at the sacrococcygeal joint' but never the coccygeal morphology types or the joint itself.
- Coccygeal morphology (Postacchini types). On a lateral radiograph the coccyx is classified by its curvature: Type I curves slightly forward with the apex pointing caudally (the commonest, least symptomatic); Type II has a more marked forward curve; Type III is sharply angulated forward; Type IV is subluxated at the sacrococcygeal or first intercoccygeal joint. The forward-angulated/subluxated types (II-IV) are more often associated with coccydynia than Type I. (This morphology classification is distinct from the Maigne dynamic-radiograph lesion classification.)
- The sacrococcygeal joint. A symphysis (a fibrocartilaginous disc between S5 and the first coccygeal segment) that normally allows a small range of passive flexion/extension (roughly 5 to 25 degrees) as the coccyx moves when sitting and defaecating; it commonly ankyloses with age, and the intercoccygeal joints are usually fused.
Q: What are the coccyx morphology types, and what kind of joint is the sacrococcygeal joint?
A: The Postacchini curvature types: I (slight forward curve, apex caudal - commonest, least symptomatic), II (marked forward curve), III (sharp forward angulation), IV (subluxated) - types II-IV (forward/subluxated) are more associated with coccydynia (distinct from the Maigne dynamic-lesion classification). The sacrococcygeal joint is a symphysis (fibrocartilaginous disc, S5-Co1) allowing roughly 5-25 degrees of passive flexion/extension, often ankylosing with age; the intercoccygeal joints are usually fused.
The Ganglion Impar (of Walther)
The topic uses 'ganglion impar block' throughout and a viva asks 'What is a ganglion impar block?' but the anatomy is never explained.
- What it is. The ganglion impar (ganglion of Walther) is the solitary, midline, most caudal ganglion of the sympathetic chain - formed where the two paired paravertebral sympathetic trunks converge and fuse - lying retroperitoneally, anterior to the sacrococcygeal junction (in front of the coccyx, behind the rectum).
- What it carries. It relays sympathetic and nociceptive afferents from the perineum, distal rectum and anus, distal urethra, genitalia and coccyx - which is why it is a target for coccygeal and perineal pain.
- The block. A ganglion impar block (local anaesthetic with or without steroid; neurolysis with phenol/alcohol or radiofrequency for malignant perineal pain) is usually placed by a trans-sacrococcygeal needle (through the sacrococcygeal disc) under fluoroscopy or ultrasound.
Q: What is the ganglion impar, and why block it for coccydynia?
A: The ganglion impar (of Walther) is the solitary, midline, most caudal sympathetic-chain ganglion, formed where the two paired sympathetic trunks converge, lying retroperitoneally anterior to the sacrococcygeal junction (in front of the coccyx, behind the rectum). It relays sympathetic and nociceptive afferents from the perineum, distal rectum/anus, distal urethra, genitalia and coccyx. Blocking it (local anaesthetic with or without steroid, or neurolysis for malignant pain; usually a trans-sacrococcygeal fluoroscopy-guided approach) interrupts coccygeal and perineal pain.
Guidelines, Registries & Global Practice
Global epidemiology
- Coccydynia accounts for under 1% of all back-pain presentations; true incidence is unknown because most cases never reach secondary care.
- Female predominance roughly 5:1, attributed to a shorter, more posteriorly angled coccyx and obstetric trauma; peak age 40-50 years (per Maigne and Wray cohorts).
- Obesity and very low BMI are both risk factors via altered sitting mechanics (Maigne 2000).
Guideline & society positions (side-by-side)
- Imaging Stance
- Isolated coccyx fracture is a clinical diagnosis; image to exclude sacral or pelvic-ring injury if mechanism warrants
- Treatment Emphasis
- Non-operative; coccyx fractures essentially never need acute fixation
- Imaging Stance
- Avoid routine radiographs for non-specific tailbone pain; reserve imaging/MRI for red flags
- Treatment Emphasis
- Conservative stepwise care; refer refractory pain to spine/pain services
- Imaging Stance
- Dynamic sit-stand radiographs to classify chronic cases
- Treatment Emphasis
- Stepwise ladder: conservative then injection/RFT/ESWT then coccygectomy
- Imaging Stance
- Fluoroscopy/US-guided block of the ganglion impar
- Treatment Emphasis
- Non-neurodestructive ganglion impar block before surgery (very-low-certainty evidence)
Registry note
- There is no dedicated coccyx implant/arthroplasty registry (no implant involved). The largest pooled outcome dataset comes from spine registries and systematic reviews (e.g. DaneSpine data within the Global Spine J review) rather than a single national registry.
High- vs limited-resource practice variation
- Well-resourced settings: ready access to MRI for red-flag exclusion, fluoroscopy/ultrasound-guided ganglion impar blocks, radiofrequency and shockwave therapy, and specialist coccygectomy in selected centres.
- Limited-resource settings: diagnosis is clinical; treatment centres on cushioning, NSAIDs, stool softeners, activity modification and physiotherapy. Injections and surgery are reserved for the rare refractory case referred to a regional centre. The good prognosis of conservative care makes this entirely appropriate for most patients worldwide.
Controversies & Areas of Uncertainty
Coccydynia is a low-evidence field: most data are retrospective, outcome measures are inconsistent, and no high-quality RCT compares the modern treatment ladder head-to-head.
Whether plain films change acute management is debated. In a clear traumatic history with isolated coccygeal tenderness, radiographs rarely alter conservative care; imaging is most useful for chronic or atypical pain to classify the lesion or exclude tumour.
The "greater than 25 degrees" cut-off for hypermobility (and posterior subluxation) derives from a small number of cohorts; normal mobility varies widely and the threshold is not universally validated. Use as a guide, not an absolute rule.
Ganglion impar block and corticosteroid injection have only very-low-certainty evidence, yet are routinely used before coccygectomy. Whether interventions meaningfully delay or prevent surgery, versus simply postponing definitive treatment, is unresolved.
Whether to excise the whole coccyx or leave the proximal segment, and the role of newer non-destructive techniques (radiofrequency, shockwave), lacks comparative trial data; practice is surgeon-dependent.
Viva Scenarios
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“What is your diagnosis and management?”
MCQ Practice Points
Q: What is the most common mechanism for coccyx fractures? A: Direct fall onto buttocks (sitting position).
Q: What is the first-line treatment for acute coccyx fractures? A: Conservative - Cushion (donut or wedge), NSAIDs, Activity modification, Stool softeners.
Q: What percentage of coccyx injuries develop chronic coccydynia? A: 10-20%.
Q: What does dynamic lateral X-ray assess? A: Coccygeal mobility. Greater than 25 degrees movement between sitting and standing indicates hypermobility.
Q: What is the surgical treatment for refractory coccydynia? A: Coccygectomy - Excision of the coccyx. Reserved for failures of 6-12 months of conservative treatment and injections.
5 F's
- Female (5x more common)
- Fat (obesity is risk factor)
- Forty (peak age 40-50)
- Fall (direct trauma mechanism)
- Fracture/Dislocation pattern
Treatment
- Cushion (Donut/Wedge) for sitting
- NSAIDs for pain control
- Stool Softeners to reduce straining
- Activity modification (avoid hard chairs)
- Time heals most (4-12 weeks)
Chronic Coccydynia
- Dynamic X-ray (sitting vs standing)
- Hypermobility: greater than 25° movement
- Ganglion Impar block first-line
- Coccygectomy for failures after 6-12 months
- 70-90% success with coccygectomy
Key Numbers
- 90% conservative success rate
- 70-90% surgery success rate
- 10-20% develop chronic coccydynia
- 10-15% wound infection post-op
- 4-12 weeks typical recovery
Evidence Base
Dynamic Radiographs Define Coccydynia Lesions
- 208 consecutive coccydynia patients imaged standing then in the painful sitting position.
- Two culprit lesions on dynamic films: posterior luxation and hypermobility; BMI determined lesion type (posterior luxation 51% in obese vs 3.7% in thin patients).
- Recent trauma (under 1 month) raised the instability rate from 55.6% to 77.1%; protocol identified the culprit lesion in 69.2% of cases.
Treatment Manipulation Outcomes by Coccyx Mobility
- Randomised pilot of three manual treatments (levator ani massage, joint mobilisation, levator stretch) in coccydynia.
- Overall satisfactory results in only 25.7% at 6 months and 24.3% at 2 years.
- Patients with a normally mobile coccyx fared best; an immobile coccyx had the poorest results.
Coccydynia: Aetiology and Conservative Treatment
- Five-year prospective trial of 120 patients; cause is a localised musculoskeletal abnormality, not lumbosacral disc prolapse.
- Physiotherapy of little help; local corticosteroid plus anaesthetic injection helped 60%.
- Injection combined with manipulation cured about 85%; coccygectomy needed in almost 20% with over 90% success.