Coccygodynia

The coccyx consists of three to five rudimentary vertebral units that are fused, except for the first coccygeal segment, which in turn articulates with the sacral cornu of the inferior sacral apex at S5 (see the image below). The sacrococcygeal articulation is either a symphysis or a true synovial joint.

Coccyx is usually formed of 3-5 rudimentary vertebrae.

Postacchini and Massobrio[4] classified coccygeal configurations into four types (see the image below).

Coccygeal configuration types I, II, III, and IV (from left to right). Type I: Coccyx is curved slightly forward, with its apex directed downward and caudally. Type II: Forward curvature is more marked, and apex extends straight forward. Type III: Coccyx most sharply angulates forward. Type IV: Coccyx is subluxated at sacrococcygeal joint or at intercoccygeal joint.

The majority of cases of coccygodynia occur in conjunction with either a subluxated or a hypermobile coccyx (often referred to as a culprit lesion). It has been proposed that the pathologic instability may give rise to chronic inflammatory changes and pain.[5] However, the study by Postacchini and Massobrio showed that there was no statistical difference between asymptomatic patients and those with coccygodynia in terms of the numbers of coccygeal segments or the incidence of fusions between the segments.[4]

Several possible causes of coccygodynia have been described. The most common of these is a single axial trauma, such as occurs with a fall directly onto the coccyx or during childbirth. However, Maigne et al suggested that only a traumatic event that occurs within 1 month of onset is significant in increasing the risk of instability and subsequent coccygodynia.[6]

Obesity is another possible cause of coccygodynia. A body mass index (BMI) higher than 27.4 in women or 29.4 in men is a risk factor for the development of both idiopathic and posttraumatic coccygodynia.[6] As high-BMI individuals attempt to sit down, the coccyx tends to jut out posteriorly as a result of inadequate sagittal pelvic rotation. This results in increased exposure to the intrapelvic pressure that occurs with sitting, ultimately causing subluxation of the coccyx.

The coccygeal configuration (see Pathophysiology) also appears to influence the cause of pain. Types II, III, and IV are more painful than type I.[4]

Coccygodynia may also occur in individuals with a normal coccyx. In such cases, the pain may derive from secondary causes, such as tumor, infection, bursitis, or posttraumatic arthritis.

Coccygodynia accounts for fewer than 1% of all back pain conditions.[7, 8, 9] It is five times more prevalent in women than in men,[10] presumably because the bone is more prominent in women than in men.[11] Although coccygodynia can occur over a wide age range, the mean age of onset is around 40 years.[10]

Several studies have reported good-to-excellent outcomes in patients undergoing coccygectomy.[12, 13, 14]

In an analytic review of 671 patients with coccygodynia who underwent coccygectomy for failed conservative management, Karadimas et al found that the procedure provided pain relief in as many as 85% of cases.[15]  The overall complication rate was 11%, including superficial as well as deep infections, delayed wound healing, infection, hematoma, and wound dehiscence.

In a study evaluating the results of 26 coccygectomies at a median follow-up of 37 months (range, 2-133 mo), Kerr et al reported excellent clinical results in 13 patients, good results in nine, fair results in two, and poor results in two.[16]  The overall favorable outcome rate was 84.6%, with a complication rate of 11.5% (mainly attributable to infection).

Ramieri et al reported the results of 28 consecutive coccygectomies for acute traumatic instability of the coccyx, of which 21 were total and seven were partial.[17]  Of the 25 patients assessed at a mean follow-up of 33 months, 19 experienced complete pain relief, two experienced incomplete relief, and four experienced no relief. Partial coccygectomies were associated with poor results.

A single-institution retrospective study by Mulpuri et al (N = 173; 77% women; mean age, 46.56 y; mean follow-up, 5.58 y) evaluated outcomes of coccygectomy for coccygodynia, comparing values for the preoperative and postoperative Oswestry Disability Index (ODI), visual analogue scale (VAS), Patient-Reported Outcomes Measurement Information System-29 (PROMIS-29), and EuroQol-5D (EQ-5D).[18]  ODI, VAS, and several PROMIS-29 domains improved postoperatively. Older age predicted continued postoperative disability; prior spine surgery, trauma etiology, and female sex predicted inferior outcomes. No outcome differences were demonstrated among coccyx morphologies.

Most patients with coccygodynia (coccydynia) give a history of a fall or an antecedent childbirth. In 1950, Schapiro described this disorder as "television disease" because most of the patients had followed poor postural adaptation while watching television,[19]  and this poor adaptation was thought to be an important predisposing factor for coccygodynia. Prolonged sitting while using a computer likewise can be a harbinger of coccygodynia.

Patients usually complain of pain that is aggravated by sitting on hard surfaces. Some patients may complain of experiencing pain during defecation and sexual intercourse or while riding a bicycle or a motorbike.

From the 1930s through the late 1960s, George Thiele published several articles relating to coccyx pain,[8]  as a consequence of which coccygodynia is still sometimes referred to as Thiele syndrome. Thiele's description of the clinical features continues to hold true today. The main symptoms include pain in the lower sacrum or coccyx or in the adjacent muscles or soft tissues. The patient usually points to the coccyx as the site of pain.[3]  The severity of pain depends on the amount of time spent sitting.

On examination, there is tenderness over the localized region.[1] In fact, absence of local tenderness over the coccyx should lead the examiner to consider other diagnoses, such as lumbar disk disease or herniated disk. A rectal and pelvic examination also should be performed to check for any masses (tumors).

The diagnosis of coccygodynia (coccydynia) is predominantly based on clinical examination. Laboratory investigations show no particular abnormality, except in the presence of infection or tumor.[3]

Radiologic investigations are helpful in diagnosis. However, because coccygodynia is a dynamic disorder, it can only be appreciated on dynamic radiographic imaging.

Dynamic radiography

Dynamic films taken in both a sitting and a standing position allow measurement of sagittal pelvic rotation and the coccygeal angle of incidence. The coccyx can move as much as 22° when a person sits or shifts from standing to sitting. Subtle posterior coccygeal subluxations can be found only when a sitting lateral film of the coccyx is compared to a standing film to check the amount of translation. Sitting and standing films will show radiographic abnormalities in as many as 70% of symptomatic cases of coccygodynia.[10] (See the image below.)

Dynamic radiographs obtained from patient with coccygodynia.

In dynamic radiographic imaging, hypermobility of the coccyx is defined as more than 25° of flexion on the lateral view; subluxation is defined as more than 25% translation of the coccyx from the standing view to the sitting view. Measurement of the intercoccygeal angle (ie, the angle formed between the first coccygeal segment and the last coccygeal segment) can provide an objective measurement of the forward inclination of the coccyx.

Computed tomography

Computed tomography (CT) plays no role in diagnosing idiopathic coccygodynia, except in cases of traumatic etiology with an obvious fracture or in cases involving infections or tumors. Contrast films may be helpful in differentiating infection and tumors.

Magnetic resonance imaging and bone scanning

Magnetic resonance imaging (MRI) and technetium-99m bone scanning may demonstrate inflammation of the sacrococcygeal area indicative of coccygeal hypermobility.[10] However, these advanced imaging techniques may not be as accurate as dynamic radiography.[5] MRI can be helpful for ruling out possible tumor. It has been used to measure the sacrococcygeal and intercoccygeal angles in patients with idiopathic coccygodynia.

Provocative diskography

Provocative diskography is a promising investigation in the assessment of coccygodynia. In a study by Maigne et al,[23] coccygeal diskography was technically successful in 44 of 51 cases and yielded positive results in all cases of subluxation and hypermobility; 50% of the patients had normal dynamic films but positive diskograms.

Fluoroscopy and injection

Pressing the region of tenderness with a blunt needle to elicit pain and subsequent relief of pain with injection of local anesthetic under fluoroscopic guidance may be helpful in confirming the diagnosis and may be therapeutic as well.

A wide variety of therapeutic methods have been proposed for the treatment of coccygodynia (coccydynia).[24] However, conservative management continues to be the mainstay of treatment.[3]

Surgical treatment is reserved for patients who do not respond to conservative management and involves the removal of the coccyx (ie, coccygectomy).[25, 26, 27] A normal appearance of the coccyx on preoperative imaging should not be considered a sufficient justification for denying patients surgical treatment when conservative management has been unsuccessful.[28]

A newer surgical procedure that has been suggested as a potential alternative for the treatment of refractory coccygodynia in patients with coccyx hypermobility is coccygeoplasty.[29]

Nonsteroidal anti-inflammatory drugs (NSAIDs) may be given to decrease the pain associated with inflammation, and laxatives may be given as stool softeners to reduce the pressure on the coccyx during defecation. These are helpful in the short term but must be combined with precautions such as using soft seats and avoiding hard seats; ring-shaped cushions may be helpful.

Injection of a local anesthetic at the site of maximum tenderness can be helpful both diagnostically (in confirming the diagnosis) and therapeutically (in relieving pain). This can be followed by injection of a steroid at the same site through the same needle left in situ.

In a study evaluating the results of dextrose prolotherapy for recalcitrant coccygodynia, Khan et al reported it to be an effective treatment option in patients with chronic nonresponding coccygodynia and advised using it in these patients before they undergo any major surgical procedure (eg, coccygectomy).[30]

Although injection is popular in practice, there is no clear consensus in the literature regarding its appropriate use. Response rates vary, as does the duration of relief.

Levesque et al studied the use of a high-concentration capsaicin patch in 60 patients with pelvic neuralgia and found that such treatment was effective and well tolerated, without serious adverse effects.[31]  Of the 60 patients, 24% reported feeling "much" or "very much" improved, with an average 58% improvement and a 3.4-point reduction in pain intensity on a numerical rating scale. Of the patients who achieved a good response, those with coccygodynia appeared to have the best results: 37% reported feeling "much" improved, with an average 63% improvement.

Ergonomic adaptation includes strapping of the buttocks, postural training, and the use of a rubber ring or a firm corset.[3]  A sitz bath over a tub of warm water may be helpful in relieving pain.

Thiele massage is a particular method of massaging the posterior pelvic floor muscles, including the coccygeus. Thiele stated that in coccygodynia, the levator ani and the coccygeus are tender and spastic, whereas the tip of the coccyx usually is not tender.[8]  He advised massage of the levator muscles along the long direction of the muscle fibers on both sides.

Although Thiele massage was found to be helpful in treating pain due to muscle spasm, it remained unhelpful in patients with pain due to coccygeal mobility. In the technique described by Mennell,[32]  the coccyx is grasped between the thumb and the index finger inserted into the anal canal, then manipulated. In addition, Maigne et al advised keeping the coccyx in a hyperextended position with the help of an index finger applied over its anterior aspect and counterpressure applied by the other hand over the posterior aspect of the sacrum.[33]

Another type of manipulation has been proposed in which the coccygeus, the levator ani, and the external sphincter are stretched by keeping the coccyx still with one finger internally and one externally. This particular technique is helpful in patients with restricted sacrococcygeal extension.

Radiofrequency (RF) ganglion impar block for pericoccygeal pain due to carcinoma, first described by Plancarte et al in 1990,[34]  has been adopted for alleviation of pain in patients with severe coccygodynia.

Atim et al presented long-term results from 21 patients treated for coccygodynia with caudal epidural pulsed RF, all of whom had failed to respond to previous conservative treatment.[35]  At 6 months after RF treatment, 12 patients (57%) had excellent results, five (24%) had good results, and only four (19%) had poor results.

Gopal et al retrospectively reviewed 20 patients treated with pulsed RF applied to the ganglion impar, reporting a successful outcome (defined as >50% improvement in visual analogue scale [VAS] score at 6 months and 12 months) in 75% of patients and an unsuccessful outcome in 25%.[36]

In a study of 39 patients with chronic coccygodynia, Sir et al (N = 39) compared pulsed RF (n = 14) with blockade of the ganglion impar (n = 25) in terms of pain intensity and patient satisfaction.[37] They found that pulsed RF neuromodulation, compared with blockade of the impar ganglion, provided significantly longer pain relief and reduced the risk of recurrence of pain in these patients.

Although extracorporeal shock wave therapy (ECSWT) has been widely used in different musculoskeletal conditions, its use in patients with coccygodynia is a comparatively recent development.

Marwan et al studied the effect of ECSWT in relieving the pain of coccygodynia in two patients, each of whom underwent a total of three treatment sessions (one session weekly for 3 consecutive weeks).[38]  Pain intensity showed a persistent decrease through the 12-month follow-up period, as evidenced by the pretherapy and posttherapy Numeric Pain Scale and VAS scores. Marwan et al subsequently reported on a larger group of patients (N = 23) and documented comparably favorable outcomes.[39]

Lin et al compared ECSWT (n = 20) with physical therapy with interferential current (n = 21) in patients with coccygodynia over a period of 4 weeks and found that the former modality reduced the discomfort and disability caused by coccygodynia more satisfactorily than the latter did.[40]  Although both VAS and Oswestry disability index (ODI) scores were significantly decreased after treatment in both groups, the decrease in the VAS score was significantly greater in the ECSWT group. The patients in the ECSWT group also had significantly higher subjective satisfaction scores.

Haghighat et al, in a quasiexperimental study aimed at assessing the efficacy of ECSWT for reducing pain in 10 patients with chronic coccygodynia, found that although decreases in VAS scores from baseline were achieved at 4 weeks and at 2 months after treatment, the decreases did not persist.[41] ​ At 7 months after therapy, there was no significant decrease in VAS from baseline.

Cases have been reported in which neuromodulation (eg, spinal cord stimulation or dorsal root ganglion stimulation) was used to treat chronic coccygodynia[42] ; however, further study is required to determine the effectiveness of such approaches for this indication.

Two main techniques of coccygectomy have been described in the literature, as follows:

• Powers technique ^[43]
• Gardner technique ^[44]

A minimally invasive endoscopic approach for performing complete coccygectomy in the setting of chorinic refractory coccygodynia was described in a case report by Roa et al.[45]

Powers technique

The patient is positioned prone, with the buttocks firmly strapped laterally for ease of exposure. A midline incision is developed down to the bone, and the sacrococcygeal joint is exposed proximally up to the tip of the coccyx distally. A subperiosteal plane is developed along the anterior surface of the coccyx, and the coccyx is lifted up. Amputation is carried out just proximal to the sacrococcygeal joint.

Gardner technique

A 7.5-cm incision is made, extending from just proximal to the sacrococcygeal joint up to the buttock crease. This incision is brought down to the fascia and the insertion of the gluteus maximus directly over the bone.

Coccygeal vessels are ligated, and the tip of the coccyx is elevated by means of blunt dissection. The tip of the coccyx is separated from the external sphincter ani by means of sharp dissection. The coccyx is then elevated from the underlying rectum and the dense fascia that separates the two. With the help of a moist sponge, the fascia and the rectum are mobilized up to the sacrococcygeal joint, and the coccyx is excised by means of sharp dissection at the sacrococcygeal joint.

The most common complication with coccygectomy is wound infection due to the presence of the abundant perineal skin flora as contaminants. Delayed wound healing is almost the rule, and pain relief may not occur for many months, even after surgical treatment. Other complications include the risk of injury to the rectum and the sphincter ani.