INTRODUCTION
Coccygodynia, first described by Simpson in 1859, is disabling pain in the coccyx that is usually provoked by sitting or changing from a sitting to a standing position. This tail bone pain may radiate rostrally to the sacrum or lumbar spine or laterally to the buttocks. Patients may rarely present with associated rectal pain or radicular symptoms One third of patients have associated back pain, contributing to misdiagnosis1,2,23,24). Due to unfamiliarity with this condition by spine specialist, many patients may suffer for years without proper treatment11,12,13,16,24). Compounding the problem, most neurosurgeons and orthopedic spine surgeons are uncomfortable treating coccygodynia due to lack of surgical training with coccygectomy. Fortunately, the knowledge to properly diagnose and surgically treat chronic refractory coccygodynia may be easily acquired. Diagnosis is based on the history and physical exam, supplemented by imaging findings and local injection of the coccyx.
To raise awareness among our neurosurgical colleagues on coccygodynia and surgical treatment, we review the literature on coccygectomy and describe the surgical technique based on our extensive experience at University of California, Davis Medical Center (UCDMC).
MATERIALS AND METHODS
Systemic data selection using PubMed
Relevant articles were retrieved with PubMed using the key words, "coccygodynia" and/or "coccygectomy". We limited the search to the English-language literature published from 1980 to January 2012. Case reports, caseseries of less than 8 patients, and editorials were excluded. Selected manuscripts were analyzed for the number of patients, age, gender, symptom duration, etiology, radiographic classification, type of surgery, use of antibiotics or drain, complications, and followup period. Statistical analysis of the data was performed using the Statistical Package for the Social Sciences (SPSS), version 16.0 (SPSS, Inc., Chicago, IL, USA). Continuous variables were expressed as the mean±standard deviation, and categorical variables were expressed as frequencies and percentages. The Chi-square test was used to evaluate any potential association of the two different surgical procedures with the postoperative outcome and complication rate. Odds ratios (OR) and 95% confidence intervals (CI), were calculated by means of simple logistic regression analysis. Statistical significance was defined as p-values <0.05.
Coccygectomy case selection at UCDMC
After the UC Davis Institutional Review Board approval was obtained, 61 patients who had coccygectomy for chronic refractory coccygodynia between 1997 and 2009 were identified. For a variety of reasons, only 26 patients participated in a telephone survey. X-rays of responders were classified according to the Postacchini and Masobrio methods (Table 1). Outcomes were categorized as excellent (complete pain relief), good (relief of most pain but mild discomfort after prolonged sitting), fair (minimal or no pain relief), or poor (pain worse after the surgery).
Surgical technique of coccygectomy
All patients received a bowel preparation preoperatively to help prevent fecal contamination of the wound and to minimize complications in the unlikely event of a rectal perforation. Intravenous antibiotics were administered prior to skin-incision. After the induction of general anesthesia, the patient was positioned prone on a Wilson frame. The buttocks are retracted laterally with adhesive tape to expose the gluteal cleft. The coccygeal region and anus are prepared with iodine or chlorhexidine. Following the skin preparation, the perianal area is isolated with a 3M 1010 Steri-Drape, and the incision site is then draped with sterile towels. The skin is infiltrated with lidocaine and epinephrine. Lateral fluoroscopic images are used to locate the sacrococcygeal junction. A midline vertical incision is made over the coccyx followed by an exposure from proximal to distal direction. After removal of the sacrococcygeal disc The coccyx is elevated and separated from the surrounding tissues circumferentially in a subperiosteal plane using monopolar electrocautery, proceeding with an en bloc resection in a rostral to caudal direction in the manner of Key at al. (Table 2).
Dissection from a proximal to distal direction avoids the risk of rectal injury, especially in the case of an anteverted coccyx. In some cases of posterior intercoccygeal subluxation, the distal segment may be removed first. En bloc resection prevents treatment failures secondary to incomplete resection. The Co-1 is identified anatomically by the cornua at the articulation with the caudal sacral segment, and is usually twice as wide as the Co2 segment. It is often helpful to resect the cornu with a Kerrison rongeur to facilitate mobilization of the coccygeal segment. In the case of a fused S5-Co1 disc, the resection proceeds distal to the first mobile segment, or alternatively an osteotomy is performed between S5 and Co1 to effect a total coccygectomy. Total coccygectomy is preferred for thinner patients, where the Co1 segment may present a symptomatic bony prominence if it is not removed. Cutting monopolar electrocautery current on a low setting is favored over coagulating current to limit damage to surrounding tissues that could result in wound infection or rectal injury. A clamp may be appliedat the lateral aspects of the coccyx to aid in posterior elevation and retraction. A complete resection may be ascertained by examining the resected specimen (Fig. 1) and by comparing a lateral C-arm fluoroscopic radiograph with preoperative imaging to ensure complete resection. All remaining sharp prominences on the caudal sacrumare smoothed using a rongeur, and bone wax is applied. After hemostasis is ensured, the overlying fascia and skin are closed in layers, with subcutaneous sutures for the skin. A liquid skin adhesive (Dermabond) is applied to help protect the wound from contamination. Broad-spectrum antibiotics are continued for 48-72 hours, and the patient receives nursing care in a lateral position or supine on a specialized sacral cutout cushion to avoid direct pressure on the surgical wound.
RESULTS
Total of 28 manuscripts met the inclusion criteria and were analyzed (Table 3). Only two of them were prospective series19,32). The majority were retrospective uncontrolled case series. In total, the reviewed series included 742 patients with coccygodynia that had coccygectomy as definitive pain management. The youngest patient was 11 and the oldest was 78 with the mean age ranging from 26.4 to 52.8 years3,8). Out of 706 patients with their sex identified, 592 were females (83.9%) and 114 were males (16.1%), with the male to female ratio of 1:5.2. The etiology of the coccygodynia was reported in all except for five articles, totalling 556 patients6,17,19,26,31). The most common causeof coccygodynia was direct trauma, reported in 325 patients (58.5%). Idiopathic coccygodynia, childbirth, and recent lumbar spinal surgery or rectal surgery or epidural injection comprised of 174 cases (31.3%).
Abnomal imaging characteristics have been described, most often using a classification system introduced by Postacchini and Massobrio which characterizes kyphotic angulation and/or subluxation (Table 1)4,8,11,15,16,24,30). Out of 176 X-raysanalyzed, there were 64 type I (36.4%), 55 type II (31.3%), 31 type III (17.6%) and 26 type IV(14.8%). Other studies describe subluxation and hypermobility of the coccyx6,19,21). Abnormal imaging on plain and dynamic x-rays, including hypermobility, ventral angulation, and subluxation, are associated with coccygodynia but are not sine qua non characteristics.
There were four (one prospective) comparative studies assessing the efficiency of injections to coccygectomy13,25,30,32). Their findings showed that injection with manipulation is effective in providing pain relief, but they also suggested that coccygectomy is a reasonable choice for those in whom the conservative management failed. Prior to coccygectomy, the majority of patients had undergone non-operative treatment modalities for a variable period of time, ranging from 3 months to 15 years.
In four papers3,6,13,30) a second generation cephalosporin was administered for 48 hours postoperatively, while the rest of the studies vary significantly as to the type and duration of their chemoprophylaxis. Maigne et al., Doursounian et al. and Pennekamp et al. have recommended the use of a drain for avoiding the void space which could compromise the results6,19,22). On the other hand, several authors deemed drain unnecessary1,11,12,33). We have not used drains at our institution. The usage of drain in close proximity to rectum may be considered as a cause for increased infection rate, but this systematic review could not confirm any direct relation between the usage of drain and rate of infections. Following surgery, laxative or enema together with a low residual diet were often used to facilitate patient's postoperative elimination management. Patient follow-up ranged from 4 months to 16 years after the surgery, with the vast majority of the studies having a mean follow-up period of more than 2 years.
Our literature review revealed that 623 out of 742 patients treated with coccygectomy had excellent or good outcome (84.0%). Some of the authors used visual analogue scale (VAS) and the Oswestry disability index (ODI) for evaluating their results3,5,6,13,16,22,23,27). Perkins et al.23) and Hodges et al.13) presented a decrease of VAS from 8.3 to 4.5 and 7.3 to 3.6, respectively. Similarly the reduction of ODI was from 35.6 to 12.5 and 55 to 36, respectively. Cebesoy et al.5) also commented that there was a progression of VAS reduction through time from 5.18 pre-operatively to 3.18 at 6 months and 2.94 and 2.76 at 12 and 24 months, respectively. Kerr et al.16) reported that the outcome appeared to be durable over time and not dependent on the cause of pain. Perkins et al.23) reported only 54% with a good outcome (7/13) probably due to the fact that most of their patients also had associated lumbar spinal disorders (10/13).
Bayne et al.2) reported 40% fair to poor outcome (19/48) and advocated against the Gardner surgical technique (Table 3) and for the use of perioperative antibiotics. Key's proximal to distal surgical technique was reported in seven studies3,4,6,16, 23,25,26,30), whereas in only one study was Gardner's distal to proximal exposure used2). Statistical analysis of the incidence of complications between the two different techniques revealed a trend toward a higher complication rate in patients treated with the Gardner method (10 of 48 patients; 20.8%) compared with Key's operation (30 of 232 patients; 12.9%), but this difference did not reach statistical signi. Overall, the risk of complications was increased by almost 80% among patients who underwent Gardner'ssurgical exposure compared with patients managed with Key's technique (OR, 1.77; 95% CI, 0.80-3.93). Patients who underwent Key's operation were more likely to have better results compared with those who were operatedwith the Gardner method; the results of Key's operation were excellent in 203 (87.5%) patients, fair in 11 (4.7%) patients and poor in only 18 (7.8%) patients, while 29 (60.4%), 11 (22.9%) and 8 (16.7%) of the patients who were managed withthe Gardner method had excellent, fair and poor results, respectively. Patients who underwent Key's operation were almost five times more likely to experience an excellent result than those who were managed with the Gardner method (OR, 4.59; 95% CI, 2.28-9.21).
The complication rates in the reviewed series varied from 0 to 50%5,26,27). All but five studies were referring to postoperative complications8,17,29,31,32). Overall wound infection rate was 10.0%(64 cases). Escherichia coli and Staphylococcus aureus were the most frequently recorded bacteria in those series with reported microbiology results. Moreover, there were 2 hematomas, 6 wounds dehiscence that lead to further surgical management, 3 persistent drainage and 6 delayed healings. There were 4 cases (0.6%) of re-do operation to excise to re-operation for excision of remnant coccyx or the distal cornua of the sacrum. Theoverall complication rate was 13.3%.
Coccygectomy series at UCDMC
The average patient age was 42 years (range 25-78 years), and the male to female ratio was 1:4. The median duration of patient-reported symptoms prior to surgery was 24 months. 58% of patients had tried local injections of steroids and/or anestheticsprior to surgery. Follow-up telephone survey was able to be obtained only from 26 patients from the entire series (42.6%). The most common cause of coccygodynia was direct trauma, recorded in 15 patients (57.7%). idiopathic coccygodynia was 8 cases (30.8%). Of note, three cases (11.5%) developed after esophagectomy, lumbar fusion and lumbar diskectomy (1 case each). The median duration of follow up from the time of surgery was 37 months (range 2-133 months). Patients had been evaluated with lateral sacrococcygeal radiographs. Of the 26 respondents, we could classifythe coccyx according to the schema described by Postacchini and Massobrio in 24 patients (Table 2). Of these coccyges, seven were Type I (29.2%), seven were Type II (29.2%), two were Type III (8.3%), and seven were Type IV(29.2%).
The number of patients with outcomes rated as "excellent," "good," "fair," and "poor" were 13, 9, 2, and 2, respectively. The favorable result (excellent or good) was 84.6%. 31% of respondents claimed they had been misdiagnosed as having some other pathological condition explaining their coccygodynia. 85% of respondents stated they would undergo the operation again if faced with the same situation. 96% of respondents would have had the procedure sooner if they had been given the option, and 85% would recommendthe surgery to others. The self-reported VAS score was significantly improved by surgery. The mean VAS score preoperatively was 9.6±0.8, and postoperatively it was 3.1±3.1 (p<0.001). There were 3 infections (11.5%) among the 26 patients. There were no rectal injuries. Two patients underwent redo coccygectomy to resect residual coccyx after initial partial coccygectomy, resulting in 1 good and 1 fair result at the time of telephone follow-up. No significant difference in outcome could be detected based on traumatic versus nontraumatic causes (p=0.33). Our numbers were small, but the outcome appeared to be durable over time and not dependent on the cause of pain.
DISCUSSION
Coccygodynia is a disabling pain in the coccyx exacerbated by sitting or rising from sitting. The pain is often pulling or lancinating in quality, may radiate to the sacrum or buttock, and may coexist with lower back pain. It may be traumatic or idiopathic in origin and is more common in women. Also coccygodynia is known as coccydynia or coccygeal neuralgia.
Imaging studies
All patients should receive a dynamic lateral sacrococcygeal x-ray in both the standing and sitting positions. This reveals the patient's coccygeal configuration (Table 1). Four types of coccygeal configurations have been described by Postacchini and Massobrio: type I (normal, curved slightly forward, seen in 68% of the general population), type II (more curved, straight forward), type III (sharply angulated), and type IV(subluxed)24). In coccygodynia, patients are less likely to have type I (31%) and more likely to have type III andIV configurations. Fusion of the sacrococcygeal joint appears to be a predisposing factor in coccygeal pain (51% versus 37% in people without coccygodynia) 24). Dynamic lateral sacrococcygeal radiographs are used to compare changes between standing and painful sitting. Radiographic instability as evidenced by posterior subluxation and hypermobility (>20° of sacrococcygeal or intercoccygeal angulation) is seen in approximately 70% of patients with coccygodynia (Fig. 2). Radiographic instability has been showen to predict excellent or good results after coccygectomy19).
Other lesions include anterior subluxation and a bony spicule on the dorsal tip of the coccyx (seen in 5% and 14% of coccygodynia, respectively). Lumbosacral MRI with contrast is recommended in all patients to define normal and abnormal bony anatomy and to rule out less common causes of coccygodynia, such as abscess or tumors. CT is superior to MRI in defining normal and abnormal bony anatomy. CT should be ordered in cases of acute pelvic trauma, and as an adjunct to MRI in evaluating neoplastic disease.
Treatment approach
Coccygodynia is managed in a stepwise fashion with increasing invasiveness. Acute coccygodynia (symptoms <2months) is managed differently from chronic coccygodynia (symptoms >2 months). Coccygectomy surgery is reserved for refractory cases. The goal of treatment is to eliminate or significantly reduce coccygeal pain and allow the patient to resume a premorbid lifestyle. Incidentally discovered tumors or other pathologies are referred immediately to appropriate specialists.
Acute coccygodynia
All patients with acute coccygodynia (symptoms <2 months) are prescribed rest and a nonsteroidal anti-inflammatory drug (NSAID) for a period of 8 weeks9). A stool softener is recommended in patients who have a history of pain with defecation, also for 8 weeks. Adjustments in seating with U-shaped cushions can relieve pressure on the coccyx. Additional therapies include sitz baths, hot mud application, acupuncture, and chiropractic manipulation. Patients who do not respond in this time frame are treated the same as patients with chronic disease who have failed acute management.
Chronic coccygodynia: initial conservative management
No universally accepted guidelines for conservative interventional management exist, but various nonoperative treatment options are available according to the experience and expertise of the physician. Non-operative treatment includes ergonomic adjustments such as a specialized cushion for sitting, application of local heat, and oral analgesics14,16,20).
Patients with newly diagnosed chronic coccygodynia (symptoms >2 months) should receive the same therapies recommended for acute coccygodynia before trying more invasive measures. Patients who have failed acute management should obtain dynamic sacrococcygeal X-rays and MRI to rule out tumor or other pathology.
Favorable results are reported after corticosteroid and local anesthetic injections given on an as-required basis20,23). They may be given alone or in combination with invasive manipulation (i.e., transrectal flexion and extension) under general anesthesia, the latter being considered more successful32). The corticosteroid plus local anesthetic should either be injected into the soft tissues around the sides and tip of the coccyx (using methylprednisolone) or the sacrococcygeal (SC) junction and dorsalperiosteum of the coccyx (using triamcinolone). However, percutaneous sacrococcygeal junction injection is sometimes recommended if local injection and/or manipulation fails, and may be accomplished fluoroscopically, or with digital rectal localization ofthe SC junction. If corticosteroid injections have no effect after 2 successive monthly injections, physical therapy combined with corticosteroid injection is an effective second-line option. Physical-therapy measures include transrectal pelvic floor massage and coccygeal mobilization32).
Chronic coccygodynia: surgery - Coccygectomy
In cases of persistent symptoms unresponsive to conservative treatment, however, coccygectomy is offered as the definitivetreatment option24,28). Different types of surgical treatment have been described but Key's method is most popular (Table 2)3,4,6,7,15,16,19,21,22,23,24,25,26,30). The coccyx can be removed either totally or partially. Surgical series have reported success rates ranging from 60% to 100% after coccygectomy1,3,4,5,6,8,11,12,13,15,19,21,22,23,25,26,28,29,30,32,33). Nevertheless, controversy exists11,24). Some have even advised against coccygectomy because they found that coccygectomy frequently failedto relieve the symptoms9).
Statistical analysis revealed that patients who underwent coccygectomy according to Key had five times more chances to havea better outcome. According to Postacchini and Massobrio, the coccyx can be removed either totally or partially with comparablegood results24). In most papers, however, total resection had better outcomes than partial resection and was recommended to reduce the chance of re-do operation11,12,15,16,21,25). Total resection requires an S5-Co1 osteotomy in the case of a sacrococcygeal synosteosis. A periosteal resection instead of a subperiosteal resrection has also been reported as an option3,22). We feel that the subperiosteal resection, which preserves the ligamentous attachments and anococcygeal ligament, is a safer and more straightforward than a periosteal and ligamentous resection, and could theoretically decrease the rare complication of rectal hernia. In our surgical case series, we encountered no cases of intraoperative rectal perforation or delayed rectal hernia associated with internal wound dehiscience. The prognosis according to etiology is variable. Kerr et al. reported that no significant difference in outcome could be detected based on traumatic versus nontraumatic causes (p=0.33)16). On the other hand, coccygectomy is more successful in cases of traumatic and postpartum coccygodynia than in idiopathic coccygodynia (75% success versus 58% success)2,22). Bayne et al. reported that coccygectomy is seldom successful for pain associated with lumbar disc disease requiring lumbar laminectomy and spine fusion2).
Surgical series have reported success rates ranging from 60% to 100% after coccygectomy1,3,4,5,6,8,11,12,13,15,19,21,22,23,25,26,28,29,30,32,33). The favorable outcome from the 28 papers was 84%. Confining coccygectomy to patients with radiographic instability on dynamic x-rays can result in good or excellent outcomes in 92% of cases (Fig. 2)19), but may exclude patients with normal imaging who would otherwise benefit.
Complications - Wound infection
Wound infection is the most common complication after surgery, with rates ranging from 2% to 22%9). Wound infection is facilitated by the location of the skin incision in the inter-lineal fold in proximity to the anus. The complication rates in the reviewed series varied from 0 to 50%5,6,13,26,27). Infection rates as high as 50% have been reported, although in recent series the rates are much lower (0-3%)1,5). Overall infection from 28 papers was 64 cases (10.0%) (Table 3). It is notable that smallcase series had the highest complication rates, ranging from 26.7 to 50%5,13,25,30). Bayne et al. reported also a large number of complications (20.6%) that was attributed to no antibiotic prescription in contrast to the rest of the authors and protocols2).
The majority were infections that resolved with antibiotic treatment or surgical debridement. Escherichia coli and Staphylococcus aureus were the most frequently recorded bacteria in those series with reported microbiology results. We were also unable to identify a direct relationship between infection and poor outcome.
There were several options to decrease the wound infection. Among the surgical approaches, Key's surgical exposure showed lower incidence of complications compared with Gardner's technique. Patients who underwent Key's operation were almost five times more likely to experience an excellent result than those who were managed with the Gardner method.
It is of note that some authors reported that sub-periosteal resection gives better results and reduce the risk of infection compared with total coccygectomy3,22).
The use of a drain along with postoperative antibiotics may reduce the incidence of postoperative wound problems including infection. There is a debate, however, on use of drainage. Bayne et al. reported a large number of complications (20.6%), but also mentioned that the lack of preoperative antibiotics, which is standard now2). There is no consensus how long antibiotics should be used postoperatively. In most papers, antibiotics were used for 72 hours after the surgery and covered bothaerobic and anaerobic organisms. Patient may be given a low residual constipating diet to avoid the need for bowel movements inthe immediate post-operative period.
Complications other than infection
Apart from infection, other complications were rare. There were 2 hematomas, 6 wounds dehiscence that lead to further surgical management, 3 persistent drainage, and 6 delayed healings. There were 4 cases (0.6%) of re-do operation to excise remnant coccyx or the distal cornua of the sacrum. None of the published case series have reported the complication of rectal hernia or rectal injury but two case reports exist.10, 18 The overall total complication rate was 13.3%.
It is notable that there were 4 case of re-do operation to resection the remnant of the coccyx. Several authors reported the advantages of performing total coccygectomy compared with partial one, which appears to be associated with an increased incidence of recurrent pain and revision surgery11,12,15,16,21,25). Residual coccygeal fragments or a prominent sacral edge in a thin patient may lead to poor outcomes and necessitate reoperation for redo coccygectomy, or rongeuring of the edge of the sacrum. We recommend total coccygectomy instead of partial coccygectomy to reduce the need for re-do operation. It can be helpful to confirm for any protrusion or remnant with C-arm just before closing the wound.
CONCLUSION
Coccygectomy has a favorable outcome as high as 84% in surgical case series. Coccygetomy has a relatively high surgical wound infection rate. When performed for an appropriate indication, coccygectomy provides an effective and long-lasting pain relief. Careful measures must be taken to reduce surgical wound infection.
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