Introduction
Coccydynia is defined as pain located at the coccyx in the area commonly known as the tailbone. The pain can also extend to the lower sacrum, adjacent muscles, and surrounding soft tissues. The coccyx is composed of one to four segments joined with the distal sacrum by the sacrococcygeal joint. The first and second segments can be mobile and predispose patients to pathological hypermobility. The anatomical structure of the coccyx is also a contributing factor to coccydynia. , The coccyx is curved forward, contains a bony spicule, and is more anteriorly subluxed, thereby placing it at higher risk for external injury. The coccygeal plexus, which has contributions from the S4–S5 nerve roots and coccygeal nerves, provides somatic and autonomic innervation to the perineum, genitals and anus.
The treatment of coccydynia can be challenging. However, a large percentage of patients’ pain resolve within weeks to months. Unfortunately, a small number of these patients will go on to develop chronic pain.
Etiology and Pathogenesis
The majority of coccydynia cases are caused by a traumatic event. Female and obese patients have a higher prevalence. The female coccyx is more posteriorly located and larger compared to males, which can leave it more vulnerable to injury during a traumatic fall or vaginal childbirth. Many cases are also idiopathic in nature and ultimately do not have an identifiable cause. Children are less likely to present with coccydynia than adolescents and adults. , ,
The innervation of the coccyx is complex. Most of the coccyx receives its innervation from the lower sacral spinal nerves and the coccygeal nerves. The anterior portion of the coccyx is innervated predominantly by the sacrococcygeal plexus, which receives contributions from the ventral rami of the S4 and S5 spinal nerves as well as the coccygeal nerves. The sacrococcygeal plexus also innervates the coccygeal ligaments, periosteum, sacrococcygeal joint, soft tissue overlying the ventral coccyx, anterior musculature of the coccyx, and external anal sphincter. The skin and soft tissue overlying the posterior portion of the coccyx is innervated by the coccygeal nerves and posterior rami of S4 and S5. Additionally, the ganglion impar, which sits at the anterior surface of the coccyx, carries visceral afferent fibers from pelvic structures, including the rectum. Therefore, coccygeal pain can actually be referred pain from nearby viscera. ,
Coccydynia pain can be divided into nociceptive or neuropathic pain. Nociceptive pain can be secondary to tissue injury, inflammation, or structural changes that can trigger a primary afferent sensory neuron. Nociceptive pain can further be divided into visceral or somatic pain. Visceral pain originates from nearby viscera and somatic pain originates from skin, muscles, and tissue. Common causes are listed in Table 6.1 .
| Somatic (Nociceptive) Pain | Neuropathic Pain |
|---|---|
|
|
Neuropathic pain results from nerve damage in the central or peripheral nervous system. Pain is characterized by burning, persistent numbness, and tingling sensations. Causes of neuropathic pain are also listed in Table 6.1 and include dural irritation from disc herniation, neoplasms and cysts located along the sacral nerve roots or at the tip of the coccyx. ,
Clinical Features
The most common clinical presentation of patients with coccydynia includes point tenderness or generalized pain over the coccyx. The pain is usually described as dull and aching with sharp stabbing pains associated with increased physical movement. Other classic symptoms include pain with prolonged sitting or standing and an exacerbation of pain when going from a seated to a standing position. The pain can become worse with a reclining angle of the spine due to additional weight bearing pressure on the coccyx, which causes hypermobility of the coccygeal bones. , It is also common for patients to feel the urge to defecate, have dyschezia, or even experience pain with bowel movements. Female patients with coccydynia may experience dyspareunia and dysmenorrhea. , ,
Patients typically respond to the pain by attempting the following alleviating maneuvers: leaning forward with the hips flexed, sitting on one buttock or leg to decrease weight bearing on the coccyx, or by avoiding prolonged sitting. It is important to note, however, that these maneuvers can also lead to increased pelvic muscle tension, resulting in pelvic floor dysfunction. , Patients tend to limit their own functional capacity by avoiding contact sports, such as cycling, due to the pain. ,
Diagnosis
Coccydynia is diagnosed predominantly based on clinical manifestations. A focused physical exam and medical history should be obtained from the patient including history of any recent trauma, vaginal delivery, and malignancy. Upon physical assessment of the patient, it is important to note the patient’s BMI. A research study has shown that a BMI greater than 27.4 in women and 29.4 in men increases the risk of developing coccydynia due to a reduction in the degree of pelvic rotation while sitting. The coccyx in obese patients is susceptible to subluxation due to increases in intrapelvic pressures that occur with falls and repetitive sitting. , , A detailed psychiatric history should also be completed to assess for anxiety or depression as an underlying cause or exacerbation of coccydynia.
Dynamic radiographs may be able to demonstrate coccygeal mobility, fusion of the sacrococcygeal and superior intercoccygeal joints, osteolytic lesions, fractures, osteoarthritis, subluxation, and pelvic rotation. A dynamic series of films include lateral and oblique views while the patient is in the sitting and standing positions. , , Further testing should be based on the patient’s clinical presentation and may include lumbar radiographs, complete blood count (rule out infectious process), stool guaiac to detect occult blood, and magnetic resonance imaging (MRI) or ultrasound to exclude occult pelvic mass or tumor. , MRI may provide better visualization of the coccyx tip where possible cysts, abscesses, bursitis, or tumors may be noted. , MRI may also be useful in showing edema or inflammation around the areas of subluxation or hypermobility.
Physical Exam Findings
A focused physical exam is used to confirm the diagnosis of coccydynia as well as to rule out other causes of pain. Physical examination should include visual inspection of the spine, sacroiliac joint, anus, and hips for general deformities. Inspection should also include surrounding skin and soft tissues to identify possible cysts, pelvic masses, fistulas, external hemorrhoids or fissures that could be the source of pain. General neurologic assessment should include lower extremity muscle strength, sensory testing of sacral dermatomes, and lower extremity reflexes. Patient with coccydynia should not present with focal neurologic deficits. ,
Moreover, patients will often exhibit point tenderness over the coccyx, sacrococcygeal ligaments, and pubococcygeal ligaments. Having the patient go from a sitting to a standing position can exacerbate the pain over the coccyx. Sharp paresthesias into the rectum with any movement of the coccyx may be noted as well. , , ,
For patients exhibiting postpartum coccydynia, the pain in the coccyx may radiate to the hip and lumbar regions especially after prolonged sitting or standing. When performing a digital rectal exam, the coccyx can be manipulated with the forefinger and thumb to elicit pain and coccyges muscle spasms. During manipulation, hypermotility or hypomotility of the sacrococcygeal joint may be noted. Palpation of pelvic floor muscles, including the levator ani and obturator internus, may demonstrate pelvic floor overactivity and hypertonia. , , It is also important to note any rectal fissures that may be a cause of referred pain.
Treatment
Unaddressed, coccydynia can cause a decline in quality of life due to worsening functional status. The majority of patients respond well to conservative treatments, particularly during the early onset of its course. When conservative treatments fail, various pain interventions are then sought out ( Fig. 6.1 ).
