Coccyx disorders almost always manifest as pain in the coccyx (coccydynia, coccygodynia). There are numerous causes of coccygeal area pain. Many of these causes involve disorders of anatomic structures near the coccyx rather than the coccyx itself. Coccydynia (coccygodynia) refers to pain in and around the coccyx.
While the exact incidence of coccydynia is not known, it is generally recognized to be far less common than low back pain in the lumbar region. Coccydynia is more common in females than in males, possibly due to sex differences in the shape and angles of the bony pelvis
Etiology of Coccyx Disorders
The most common causes of coccyx disorders are musculoskeletal. These can be categorized as involving
Acute trauma
Repetitive microtrauma
Acute trauma can involve external (from outside the pelvis) or internal (from inside the pelvis) physical force.
External physical trauma includes falling and landing directly on to the coccyx, which can cause fracture, dislocation, ligamentous disruption, and joint instability. Other external trauma to the coccyx can occur from sudden bumping during recreational activities such as from water-slides, snowmobiles, and horseback riding.
Internal physical trauma to the coccyx classically includes childbirth, in which passage of the neonate through the birth canal can injure the coccyx.
Repetitive microtrauma to the coccyx can occur from activities such as cycling or potentially due to prolonged sitting. Degenerative osteoarthritis of the coccygeal joints and chronic pain may result from years of repetitive microtrauma.
The persistence of coccydynia following trauma is affected by the interaction between the individual patient's anatomy (coccygeal size, shape, angulation, and flexibility) and the mechanical forces exerted onto the patient's coccyx. A common consequence is dynamic instability of the coccyx (excessive movement at the coccygeal joints during weight-bearing while sitting). Other common abnormalities include distal coccyx bone spurs, which typically become chronic and can be either post-traumatic or idiopathic. Occasionally, coccydynia can be part of a generalized central pain syndrome.
Less common causes of coccyx disorders include nontraumatic disorders such as
Tumors (benign and malignant)
Infection
Arthropathies (eg, ankylosing spondylitis)
Coccygeal cancers are rare causes of coccygeal pain. The cancers can be primary (ie, originating in the coccyx) or secondary. Primary coccygeal cancers include chordoma, a primary bone cancer that has a tendency to occur at the sacrococcygeal region and is often fatal. Secondary coccygeal cancers may result from direct invasion from adjacent structures (eg, from rectal cancer) or be metastatic from malignancies elsewhere in the body. Benign coccygeal tumors include sacrococcygeal teratomas.
Coccygeal infection is rare, but can include osteomyelitis of the coccygeal vertebral bodies after sacrococcygeal pressure ulcers. Also, tuberculosis of the coccyx is rare, but has been reported.
Symptoms and Signs of Coccyx Disorders
Pain from a coccyx disorder is typically located in the midline, 2 finger breadths posterior/superior to the anus, and is typically worse while sitting, particularly sitting while leaning partway backward. Many patients also report momentary but substantial worsening of their pain during the transition from sitting to standing. Many patients have few or no symptoms while standing or walking.
Pain lateralized to one side or the other suggests a non-coccygeal disorder, or secondary spasm of the pelvic floor muscles in response to the coccyx pain. However, many patients have poor body awareness of their coccygeal region and have difficulty identifying the specific site of their pain.
Physical examination includes direct palpation of the coccyx to see if this reproduces the patient's symptoms. Coccyx palpation can be done externally, preferably while the patient is lying on their side with their hips flexed so that the coccyx region is easier to see and palpate. Internal palpation of the coccyx via digital rectal examination may be necessary. Instability of the coccyx may be assessed by the clinician moving the coccyx through its range of motion with one finger anterior to the coccyx (within the rectum) and one finger posterior to the coccyx (on the skin).
Coccygeal osteomyelitis/joint infection may present with overlying warmth and erythema.
Diagnosis of Coccyx Disorders
History and physical examination
Sometimes radiographs
Rarely MRI or bone scan
Typically, history and physical examination allow distinction between a coccygeal and non-coccygeal disorder (see also Evaluation of coccygeal area pain). If the source is unclear, clinicians should ask about symptoms (eg, pain, dysfunction) involving the genitals, urinary bladder, reproductive organs, and lower gastrointestinal tract (rectal, anal, and perianal regions) and whether there is history of malignancy (especially in the pelvic region).
If the coccyx is determined to be the site of the disorder, a traumatic cause is often apparent clinically, and patients with mild, acute pain probably do not require any diagnostic testing. However, if the pain is more severe or prolonged (eg, lasting more than 2 weeks), or the etiology is unclear, then imaging studies are recommended.
Imaging of the coccyx
Standard imaging studies, including radiographs, MRI, CT, and bone scan, may be done of the coccyx, but because of the location of the coccyx in relation to other nearby structures, slight alterations of technique from standard "pelvic" or "lumbosacral" studies are needed. Radiology technicians should be advised that the coccyx is the structure of interest.
Radiographs of the coccyx are usually done first, typically including anteroposterior (AP) and lateral views. Note that a standard AP view of the pelvis often results in the pubic bones obstructing the view of the coccyx . Thus, specific coccygeal views should be ordered, in which the AP view is modified by adjusting the cephalad-caudad tilt so that the coccyx no longer overlaps the pubic bones. The pelvic organs and stool/gas within the rectum may still somewhat obscure the AP view of the coccyx.
The lateral view of the coccyx is typically initially done while the patient is standing or supine, preferably with a collimation tube placed on the x-ray source to improve the visualization of the coccygeal bones. Collimation is especially important when assessing for a distal coccyx bone spur, a common cause of coccydynia. However, if possible, the lateral views should be done in both the seated and standing position, which is the best method to assess for coccygeal dynamic instability, the most common anatomic abnormality in patients with coccydynia. The position and angle of the coccyx while the patient is standing are compared to measurements done while the patient is bearing weight on the coccyx (sitting leaning partly back). Normally, sitting causes the coccyx to flex forward by < 20° (1) and the coccygeal vertebral bodies may shift (called listhesis, or luxation) ≤ 25% of the vertebral body depth (2). Greater flexion and/or shift indicate coccygeal dynamic instability.
Pearls & Pitfalls
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Advanced imaging studies of the coccyx include MRI and CT scans. MRI or CT scans are typically necessary to detect chordoma, soft-tissue tumors (eg, retrorectal hamartoma or tailgut cyst), osteomyelitis, abscess, or pilonidal cyst. MRI is preferred because it does not expose pelvic organs to ionizing radiation and can assess both bony details and also soft tissue abnormalities. Ideal views of the coccyx should include thin, midline sagittal slices. These should be done in both T1 (to best show bony anatomy) and T2 or STIR (to best show any fluid/inflammation in the area).
Note that a "lumbosacral" MRI or CT scan will include the lumbar spine and the upper portion of the sacrum, but will typically not include the coccyx. Also, a typical "pelvic" MRI or CT scan will not include midline sagittal views of the coccyx. Thus, specific views of the coccyx must be included in the orders.
Nuclear bone scans may be useful in the small percentage of coccydynia patients in whom bony destruction from cancer or osteomyelitis is suspected. A 3-phase nuclear medicine bone scan routinely includes both anteroposterior (AP) and posteroanterior (PA) views. However, the nuclear agent collects in the urinary bladder prior to urination, which results in the urinary bladder (in the anterior pelvis) obscuring the view of the coccyx (at the posterior pelvis) in both AP and PA views. Thus, to visualize the coccyx, lateral views of the pelvis must be included.
Diagnosis references
1. Maigne JY, Guedj S, Straus C: Idiopathic coccygodynia. Lateral roentgenograms in the sitting position and coccygeal discography. Spine (Phila Pa 1976) 19(8):930-934, 1994. doi:10.1097/00007632-199404150-00011
2. Maigne JY, Tamalet B: Standardized radiologic protocol for the study of common coccygodynia and characteristics of the lesions observed in the sitting position. Clinical elements differentiating luxation, hypermobility, and normal mobility. Spine (Phila Pa 1976) 21(22):2588-2593, 1996. doi:10.1097/00007632-199611150-00008
Treatment of Coccyx Disorders
Prevention
Oral analgesics
Sometimes local injections (corticosteroids and/or local anesthetic)
Rarely nerve ablation or surgical coccygectomy
Treatment of coccydynia typically involves a stepwise approach, starting with simple and noninvasive options (1).
Avoiding activities that worsen the pain is important. Patients may need to stop cycling, riding motorcycles, horseback riding, and doing certain exercises such as sit-ups. If mere sitting is painful, patients who work at a desk can use a standing workstation.
Cushions help when sitting is painful. Cushions with a triangular wedge cut-out or a U-shape allow the patient to sit bearing weight on their ischial bones, while the coccyx hovers above the empty area of the cushion . Doughnut cushions (a ring-shaped cushion with the hole in the center) are typically less helpful for coccydynia patients because the back ring of the cushion may press painfully on the coccyx or lower sacrum.
Oral analgesicsnonopioid analgesics may help and may be adequate for patients with moderate, acute coccygeal pain. However, they may cause systemic adverse effects and may not be as effective as medications injected directly at the coccyx.
Topical medications2).
Local injections at the coccyx are usually done under fluoroscopic guidance by a pain medicine specialist. Local injections typically target somatic nerves at the posterior coccyx. However, the site of injection should be individualized to the specific patient based on history, physical examination, and imaging studies to target a specific joint, bone spur, nerve, or other anatomic structure. In patients whose coccydynia includes a component of sympathetically-maintained pain, a nerve block can be done at the ganglion impar, located anterior to the upper coccyx.
3, 4). This sustained therapeutic response to local anesthetic has sometimes been referred to as 'resetting the thermostat' or 'rebooting the computer' and can provide durable improvement in the patient's baseline pain.
Injections can be repeated if a single injection fails to provide adequate relief or if the pain returns months or years later.
Nerve ablation
Coccygectomy is surgical amputation, or removal, of the coccyx. This procedure is reserved for the small percentage of patients who have substantial and persistent pain despite trying all nonsurgical approaches. Coccygectomy can be either complete (removing the entire coccyx) or incomplete (where part of the coccyx is left in place). The most common complications of coccygectomy include postoperative infection and persistent coccygeal pain (which may be a form of phantom pain similar to that seen with limb amputations). Post-coccygectomy pain can be treated by medications, cushions, local injections, and pelvic floor physical therapy; some cases may require repeat surgery to remove infected tissue or retained bone fragments.
Consultation with a specialist in evaluating and treating coccygeal pain may be helpful for clinicians who are not familiar with the details of diagnosis and treatment of coccydynia, especially if the clinician is not able to identify an anatomic cause for the pain or simple therapeutic measures have not provided adequate relief.
Treatment references
1. Daily D, Bridges J, Mo WB, Mo AZ, Massey PA, Zhang AS. Coccydynia: A Review of Anatomy, Causes, Diagnosis, and Treatment. JBJS Rev. 2024;12(5):e24.00007. Published 2024 May 6. doi:10.2106/JBJS.RVW.24.00007
2. Foye PM, Shupper P, Wendel IPain Physician. 2014 Mar-Apr;17(2):E229-33. PMID: 24658491
3. Mitra R, Cheung L, Perry P. Efficacy of fluoroscopically guided steroid injections in the management of coccydynia. Pain Physician 2007 Nov;10(6):775-778. PMID: 17987101
4. Sencan S, Edipoglu IS, Ulku Demir FG, Yolcu G, Gunduz OH. Are steroids required in the treatment of ganglion impar blockade in chronic coccydynia? a prospective double-blinded clinical trial. The Korean Journal of Pain 2019 Oct;32(4):301-306. DOI: 10.3344/kjp.2019.32.4.301
Key Points
Severe or chronic tailbone pain can substantially compromise a patient's quality of life.
Most coccygeal disorders involve acute or chronic trauma, but tumors, infections, and arthropathies must be considered.
Many patients do not require imaging studies but, when done, sitting-versus-standing radiographs of the coccyx should be done to assess whether there is any abnormal movement of the coccyx while the person is sitting.
MRI or CT scan may also be helpful in selected patients.
Use a step-wise approach to treatment, starting with the simplest and least invasive options first, including activity modification, cushions, and local injections before considering surgery.
A common complication of coccydynia is a chronic pain syndrome, which may be avoided by appropriate and timely evaluation and treatment.
