Definition

Coccydynia describes pain in the vicinity of the coccygeal bone at the base of the spine. It may be localized to the lower sacrum, the coccyx, or the adjacent muscles or soft tissues. Pain can be insidious or sudden in onset. Symptoms are usually triggered by sitting, especially leaning back while sitting, prolonged standing, or rising from a seated position.

Onset is most frequently in adolescents and adults, but it can occur over a wide range of ages. The most common inciting factor is trauma to the coccyx or surrounding soft tissue from a vertical axial blow or cumulative trauma from a difficult vaginal delivery. However, idiopathic coccydynia accounts for one-third of cases. Pathologic features may range from dislocated sacrococcygeal fracture to ligamentous damage of the caudal coccygeal segments. In most cases, the tip of the coccyx is subluxated or hypermobile ( Figs. 99.1 and 99.2 ).

Lateral radiographs of coccygeal subluxation.

From Doursounian L, Maigne JY, Faure F, et al. Coccygectomy for instability of the coccyx. Int Orthop. 2004;28:176–179.

Sagittal magnetic resonance image of misaligned coccygeal fracture.

From Pennicamp PH, Kraft CN, Stuetz A, et al. Coccygectomy for coccygodynia: does pathogenesis matter? J Trauma. 2005;59:1414–1419 .

The coccyx consists of three to five rudimentary vertebrae. The first coccygeal segment has transverse processes that articulate and occasionally fuse with the sacrum. This vertebra is usually separate from the remaining coccygeal vertebrae, which may partially or completely fuse, leading to anatomic variations of one to four total bony coccygeal segments.

The fibrous sacrococcygeal symphysis connects the sacrum to these segments of the coccyx. This joint is reinforced by sacrococcygeal ligaments, which enclose the final intervertebral foramen through which the S5 roots exit. The S4, S5, and coccygeal roots contribute to the coccygeal plexus, which provides rich somatic and autonomic innervation to the anus, perineum, and genitals. The levator ani (innervated by S3-S5 nerve root branches through perineal and inferior rectal nerve branches of the pudendal nerve) and coccygeal muscles (innervated by S3-S5 nerve root branches) attach to and support the coccyx during defecation and childbirth. The gluteus maximus also attaches to the lateral coccyx and can contribute to a sensation of pressure while sitting.

Morphology of the coccyx may have a role in coccydynia. The coccyx that is markedly curved or angled forward, is anteriorly subluxed or laterally deviated, or contains a bone spicule is more prone to pain. Obesity is an independent risk factor for coccydynia. Increased body mass can alter seated weight distributions and determine the location of the lesion. Degeneration of disc structures, referred pain from lumbar disc disease, and compression of the sacral plexus have also been implicated. There are also reported cases of rare coccydynia pathologic processes, including tuberculosis, tumors, and calcification of the joints or tendons. Prevalence of coccydynia is four to five times higher in women than in men. In addition to obstetric trauma, the increased susceptibility to injury in women is attributed to anatomy as the female coccyx is more posterior in location and larger than the male coccyx, making it more susceptible to external trauma. Less common etiologies of coccydynia include neoplasm, cystic deposits, and infections.

Symptoms

Coccygeal pain is located at the tip or sides of the coccyx. The quality of pain is usually dull and achy at baseline and intermittently sharp during activities that aggravate the symptoms. A sensation of pressure or an urge to defecate is also commonly described. Coccydynia has been associated with dyspareunia, dyschezia, dysmenorrhea, and piriformis syndrome. Symptoms are usually exacerbated by sitting on hard surfaces, prolonged sitting, and moving from the sitting to the standing position. Symptoms are generally relieved by taking weight off the coccyx.

Levator ani syndrome and proctalgia fugax are variants of coccydynia.

Levator ani syndrome is characterized by a dull ache or pressure sensation in the rectum, with pain episodes lasting more than 30 minutes at a time and symptoms persisting for at least 3 months. Symptoms tend to be more severe during the day than at night. Symptoms may result from injury to or hypertonicity of the levator ani, piriformis, and internal obturator muscles or inflammation of the arcus tendon. In parous women, this most often involves injury of the pubococcygeus muscle. This syndrome is associated with muscle tenderness with traction of the puborectalis portion of the levator ani on rectal examination.

Proctalgia fugax is the sudden onset of excruciating anal pain lasting a few seconds or minutes, but less than 30 minutes, then disappearing completely. Proctalgia fugax is characterized by spastic muscle contractions of the pelvic floor. Symptoms are not typically related to defecation but may be associated with sexual intercourse, increased anxiety, or stress. Symptoms are usually nocturnal and awaken the patient from sleep. Unlike coccydynia, which is more common in women, proctalgia fugax occurs equally in men and women.

Physical Examination

Inspect the sacrococcygeal region including the anus, surrounding skin, and soft tissue for cysts, fistulas, external hemorrhoids, and fissures. Palpate the pelvic area for evidence of lymphadenopathy or pelvic masses to rule out neoplastic or infectious disease (see the section on differential diagnosis). Assess for point tenderness or palpable abnormalities along the pelvic girdle, including the tip of the coccyx where a spicule would be located. It is also important to palpate surrounding joints. Classic findings in coccydynia are exquisite tenderness to direct palpation of the coccyx, sacrococcygeal ligaments, and pubococcygeal ligaments. Evaluate for leg length discrepancy, pelvic obliquity, sacroiliac motion, and sacroiliac joint tenderness because correction of these problems may be part of the treatment. Lower extremity strength, reflexes, and sensation should be assessed for focal neurologic deficits and should be normal in coccydynia. Digital rectal examination should include testing for occult blood, palpation for internal masses, and palpation of the levator ani muscles for tenderness. Gentle manipulation of the coccygeal tip, the pubococcygeal ligament, and the sacrococcygeal joint should be performed to assess for tenderness and hypermobility.

Functional Limitations

Because coccydynia is often worsened by sitting, driving can become very painful. Sedentary work involving prolonged sitting may exacerbate symptoms; frequent breaks may be required. It is common to avoid social situations because of pain when sitting. Because of pressure to the coccyx and muscle contractions in the perineum during orgasm, sexual intimacy can worsen symptoms and is often avoided. Equestrian activities, cycling, and contact sports can also be particularly painful.