Tailbone Injury

Tailbone injury is injury to the coccyx (the terminal 3 to 5 fused vertebrae) and its surrounding ligaments and muscles, ranging from contusion and sprain to subluxation, dislocation or fracture. The coccyx is the attachment for the levator ani, the coccygeus and part of the gluteus maximus, and the anococcygeal ligament.

• Commonest mechanism: a direct fall onto the buttocks (slipping on stairs, ice, wet floors, sports falls, horse riding, cycling). Other mechanisms are repeated pressure from prolonged sitting on hard surfaces, vaginal delivery (a coccyx forced backwards by the fetal head, with forceps or a large baby), and direct blows in contact sport.
• It is about 5 times more common in women than men, because the female coccyx is more exposed, the pelvis is wider, and childbirth adds risk. Obesity increases the risk of subluxation after a fall, and low body mass index increases the risk through loss of padding.
• Most injuries are minor and settle in 8 to 12 weeks. About 10 to 20% develop persistent pain beyond 3 months, which then needs a different approach.
• Osteoporosis, long term corticosteroid use and menopause make fracture more likely after a low energy fall.

• Pain and tenderness localised over the coccyx at the top of the natal cleft, worse on sitting (especially on hard seats and leaning back), on rising from sitting, and with prolonged sitting. Pain may be eased by leaning forwards or sitting on one buttock.
• Pain on defecation, on sexual intercourse, and on cycling or riding. Bruising over the sacrococcygeal area may appear 24 to 72 hours after the fall.
• Pain on pressing the coccyx externally. On gentle internal rectal examination, a mobile, tender, flexed or displaced coccyx suggests subluxation or fracture. Normal coccygeal movement is a few degrees only, and abnormal mobility or crepitus suggests fracture.
• Differential diagnosis: sacral or sacroiliac fracture, pilonidal disease, perianal abscess, anal fissure, levator ani syndrome, proctalgia fugax, piriformis syndrome, lumbar disc disease with referred pain, pelvic floor dysfunction, endometriosis, prostatitis, rectal or pelvic tumour (chordoma, sacral tumour), and osteomyelitis.
• Red flags: saddle numbness, new bladder or bowel dysfunction, bilateral leg weakness (cauda equina syndrome); fever, a discharging sinus or a swelling (infection); weight loss, night pain or a previous cancer (tumour); high energy injury with pelvic ring involvement; and an unexplained fall in an older adult (check for fragility fracture).
• Complications: chronic coccydynia, constipation and painful defecation, sciatic type radiation, depression and sleep loss from persistent pain, and, rarely, non-union with a mobile painful fragment.

• Clinical, from the history of a fall and the tenderness over the coccyx. Examine the spine, sacroiliac joints, pelvis and perineum, record anal tone and perianal sensation, and check lower limb power, sensation and reflexes.
• Rectal examination is the best way to assess coccygeal mobility, with the thumb outside and the index finger inside, but it needs consent, a chaperone and gentle technique. Defer it if the patient cannot tolerate it, and record the reason.
• X-ray of the sacrum and coccyx (lateral view, ideally with a sitting and a standing lateral view) is indicated when there is high energy trauma, severe pain or suspected fracture, and in older adults. It shows fracture, dislocation and angulation. A normal X-ray does not exclude a fracture or ligament injury.
• Sitting and standing lateral views show dynamic instability: posterior luxation of the coccyx on sitting, or an increase in coccygeal flexion of more than 25 degrees between the standing and sitting views (the resting intercoccygeal angle itself varies between about 10 and 30 degrees depending on the type of coccyx).
• MRI or CT is used for diagnostic doubt, suspected tumour, neurological signs, or chronic pain that does not settle. MRI shows bone marrow oedema and ligament injury.
• Laboratory tests are needed only when infection or tumour is suspected: full blood count, C-reactive protein, erythrocyte sedimentation rate and, in older adults with a fragility fracture, calcium, vitamin D and bone profile.
• Pregnant and postpartum patients: examine with care, and use ultrasound or MRI when imaging is needed, avoiding ionising radiation unless essential.

• Most patients need only conservative management:
  • Avoid prolonged sitting on hard surfaces, and take short, regular breaks from sitting every 20 to 30 minutes.
  • Use a wedge or donut shaped (coccyx cut out) cushion, and lean forwards when sitting to move weight onto the thighs and ischial tuberosities.
  • Apply ice for 10 to 15 minutes every 2 to 3 hours for the first 48 hours, then heat for 15 to 20 minutes 2 to 3 times a day.
  • Avoid cycling, horse riding and rowing until pain has settled.
• Analgesia:
  • Paracetamol 1 g orally 6 hourly (maximum 4 g per day, 3 g if weight below 50 kg, liver disease or chronic alcohol use).
  • Ibuprofen 400 mg orally 8 hourly with food for 5 to 10 days, or naproxen 500 mg orally 12 hourly with food, with a proton pump inhibitor such as omeprazole 20 mg once daily if there is an increased gastrointestinal risk. Avoid in renal impairment, active peptic ulcer disease and uncontrolled hypertension or heart failure.
  • Short term codeine 30 mg orally 6 hourly (maximum 240 mg per day), or tramadol 50 mg orally 6 to 8 hourly, only for severe pain for up to 5 to 7 days, because both worsen constipation and cause drowsiness.
  • Topical diclofenac 1% gel 2 to 4 g applied to the sacral area 3 to 4 times daily, which has little systemic absorption.
• Prevent constipation, because straining and hard stools aggravate pain: increase fluid and fibre, and give lactulose 15 mL orally twice daily, or macrogol (polyethylene glycol) 1 sachet orally once or twice daily, or docusate sodium 100 to 200 mg twice daily, and stop when stools are soft.
• Physiotherapy: pelvic floor relaxation and stretching, gentle sacroiliac and lumbar mobility, and, in persistent pain, manual coccygeal mobilisation or levator ani release by a trained clinician.
• Persistent pain beyond 6 to 8 weeks:
  • Image the coccyx if not already done, and review the diagnosis.
  • Image guided or palpation guided injection of the coccyx and sacrococcygeal joint with methylprednisolone 40 mg and bupivacaine 0.25% (5 to 10 mL), or with lidocaine 1% 5 mL. Relief is reported in 60 to 85% of patients, and the injection can be repeated once after 4 to 6 weeks. Limit corticosteroid injections to 3 per year.
  • Ganglion impar block (the sympathetic ganglion at the sacrococcygeal junction) with local anaesthetic and a steroid, for pain that persists after local injection. Radiofrequency ablation is an option in specialist centres for recurrent cases.
  • Amitriptyline 10 mg orally at night, increased by 10 mg every 1 to 2 weeks to 25 to 50 mg for neuropathic features, or gabapentin 100 to 300 mg at night, increased to 300 mg 3 times daily, adjusted for renal function.
• Surgery: partial or total coccygectomy is reserved for pain that persists after 6 months of conservative and injection therapy, with confirmed instability or deformity on dynamic imaging, and a good response to a diagnostic injection. About 70 to 85% have good relief, and complications (wound infection in 10 to 20%, dehiscence, delayed healing) are more frequent than in most spinal procedures. Give prophylactic cefazolin 1 to 2 g IV before the incision.
• Fracture or dislocation: reduction is rarely needed. A displaced coccygeal dislocation causing severe pain can be manipulated under sedation and analgesia by a specialist, but recurrence is common.
• Special groups:
  • Pregnancy and postpartum: use paracetamol, a cushion, positioning and gentle physiotherapy. Pain usually settles within 3 to 6 months. Ibuprofen is compatible with breastfeeding.
  • Elderly: consider a possible fragility fracture, check bone health, and avoid NSAIDs in renal impairment and with anticoagulants.
  • Children: pain after a fall settles with rest and a cushion, and a child with persistent pain or neurological signs needs imaging.
  • Obesity: encourage weight loss, use a wider cushion, and examine for subluxation, which is more frequent.
  • Anticoagulated patients: take care with injections, and check the international normalised ratio when using warfarin.
• Follow up: review at 2 to 4 weeks, and at 3 months if symptoms continue. Refer to orthopaedics, pain medicine or a spinal specialist for pain beyond 3 months, neurological signs, suspected tumour or infection, or a need for injection or surgery.