Pelvic Electric Potential as a Marker of Autonomic Dysfunctions and Risk Factor of Neurogenic Arrhythmias in Humans.

Differential high-resolution ECG (V1-V2) and pelvic electric potential measured between the coccyx and perineum were recorded simultaneously in resting supine position in men with autonomic nervous system disorders (N=37). In healthy volunteers (N=23), the effective (rms) value of PEP presented by median and interdecile range was 30 (20-80) µV within the frequency band of 0.03-80 Hz. In patients, the corresponding value was significantly higher: 140 (80-280) µV. In both groups, the amplitude harmonic spectrum of pelvic electric potential decreased monotonically with frequency according to 1/f1.6 law. In some patients (N=16), rare single or grouped high-amplitude impulses (up to 1 mV) of pelvic electric potential with total duration of about 1 sec were observed; of them, some persons (N=7) demonstrated practically one-to-one synchronous relations between these impulses and arrhythmia episodes indicating abnormal activity of the autonomic nervous system as their most probable common cause. The high-amplitude pelvic electric potential impulses were also observed in ECG records as interference signals with an amplitude attaining 50 µV. Thus, high-resolution ECG and pelvic electric potential can reveal the risk of abnormal neurogenic influences on the heart. The data obtained are discussed in relation to diagnostics of the autonomic nervous system disorders, neurogenic arrhythmias, and risk of sudden cardiac death.

Management of persistent coccydynia with transrectal manipulation: results of a combined procedure.

OBJECTIVE: We compared the results of manual therapy combined with steroid injection with single steroid injection in the treatment of persistent coccydynia. PATIENTS AND METHODS: Combined therapy was performed in 21 patients (Group 1) and steroid injection in 23 patients (Group 2). We compared two groups and investigated the combined therapy group in details. Patients were classified according to the underlying cause, BMI, anatomic type of coccyx and duration of symptoms (< 6 or ≥ 6 months). RESULTS: Mean age was 30.5 years at the time of procedures. Mean followup time was 27.8 months. VAS scores were decreased in both groups but combined therapy group had much more better results. Complete pain relief was achieved in 61.9% of patients in Group 1 whereas it was only 17.4% in Group 2. In 23.8% of Group 1, the VAS score was significantly decreased but the feeling of uncomfortability persisted. This was 73.9% in Group 2. We had no relapse in Group 1 but in Group 2 the relapse rate was 56.5%. Underlying cause, body mass index, anatomic type of coccyx and duration of symptoms had no effect on results. CONCLUSION: Manual therapy combined with steroid injection would be an alternative method in case of persistent coccydynia. It is a safe and easy option before surgical treatment.

Ankylosing spondylitis and a diagnostic dilemma: coccydynia.

OBJECTIVES: Coccydynia is defined as pain in or around the tail bone area. The most common cause of coccydynia is either a trauma such as a fall directly on to the coccyx or repetitive minor trauma. The etiology remains obscure in up to 30% of patients. The literature on the contribution of rheumatic diseases to coccydynia is scarce. Our objective was to investigate the prevalence of coccydynia in ankylosing spondylitis (AS) patients. METHODS: One hundred and seven consecutive patients with AS were evaluated for coccydynia were enrolled between January and November 2012 for a cross-sectional analysis. Seventy-four consecutive patients were followed for mechanical back pain as controls and the AS patients were interviewed for the presence of coccydynia. The data collected was evaluated on SPSS® version 11.5 and Microsoft Excel® Programmes. RESULTS: Prevalence of coccydynia in AS (38.3%) was significantly higher than the control group (p<0.0001) in both female and male AS patients (female AS vs. control=40.9% vs. 18.4%, p=0.015 and male AS vs. control=36.5% vs. 8.0%, p=0.005). Both genders were affected equally in the AS group whereas coccydynia was slightly more frequent in female patients in the control group. CONCLUSIONS: Coccydynia is a previously neglected symptom of AS and it is almost three times more common in AS than in non-specific chronic low back pain. Our observation may implicate that inflammatory diseases have a role in the etiology of coccydynia, especially in those without a history of recent or past trauma and coccydynia may be a factor associated with the severity of AS as well.

Acute traumatic instability of the coccyx: results in 28 consecutive coccygectomies.

INTRODUCTION: Coccygeal instability includes hypermobility, subluxation and fracture-dislocation. Surgical resection is still controversial, with intractable post-traumatic coccygodynia being an indication to surgery. MATERIALS AND METHODS: From 2001 to 2010, we enrolled 31 patients with post-traumatic coccygodynia (19 females, 12 males; mean age 31 years, range 21-47). Conservative treatment failed in 28 patients, who underwent surgical resection of the coccyx. Twenty-one were total, while seven were partial coccygectomies. At follow-up (mean 33 months; range 24-70), clinical outcomes evaluation included measurement of complications rate, pain relief and satisfaction degree. RESULTS: Nineteen patients experienced complete pain relief, while two had incomplete, and four had no relief. Partial coccygectomies were associated with poor results. Twenty-one patients were satisfied, whilst four were not. CONCLUSIONS: Coccygectomy is the treatment of choice for post-traumatic instability. Patients' selection allowed excellent or good results. This study favors a more aggressive approach including total resection of the coccyx.

The efficacy of coccygectomy in patients with persistent coccydynia.

AIMS: The aim of this study was to investigate the efficacy of coccygectomy in patients with persistent coccydynia and coccygeal instability. METHODS: The Danish National Spine Registry, DaneSpine, was used to identify 134 consecutive patients who underwent surgery, performed by a single surgeon between 2011 and 2019. Routine demographic data, surgical variables, and patient-reported outcomes, including a visual analogue scale (VAS) (0 to 100) for pain, Oswestry Disability Index (ODI), EuroQol five-dimension questionnaire (EQ-5D), and the Physical Component Score (PCS) and Mental Component Score (MCS) of the 36-Item Short-Form Health Survey questionnaire (SF-36) were collected at baseline and one-year postoperatively. RESULTS: A total of 112 (84%) patients with a minimum follow-up of one year had data available for analysis. Their mean age was 41.9 years, and 15 (13%) were males. At 12 months postoperatively, there were statistically significant improvements (p < 0.001) from baseline for the mean VAS for pain (70.99 to 35.34), EQ-5D (0.52 to 0.75), ODI (31.84 to 18.00), and SF-36 PCS (38.17 to 44.74). A total of 78 patients (70%) were satisfied with the outcome of treatment. CONCLUSION: Patients with persistent coccydynia and coccygeal instability resistant to nonoperative treatment may benefit from coccygectomy. Cite this article: Bone Joint J 2021;103-B(3):542-546.

Coccygectomy with or without periosteal resection.

The purpose of this study was to compare the clinical outcomes and wound complications in coccygectomy with or without subperiosteal resection. This retrospective study included 25 patients who underwent coccygectomy. Resection of all mobile coccygeal segments including the periosteum was performed in 11 patients (group 1) and resection was performed subperiostally sparing the periosteum in the remaining 14 patients (group 2). A visual analogue scale was used for pain assessment before and after the surgery both in sitting and standing positions. A questionnaire to evaluate subjective patient satisfaction was also used. The two groups were statistically similar in terms of age, sex, aetiology, duration of symptoms before surgery and follow-up time. Both surgical techniques resulted in a statistically similar clinical outcome. Overall, 84% of patients who underwent coccygectomy benefited from surgery. We observed four wound infections (two superficial and two deep) that caused delayed wound healing in group 1. The rate of infection in group 1 was statistically higher than in group 2. The results of this study suggest that periosteal preservation and closure are related to low risk of infection.

14. Coccygodynia.

Coccygodynia is painful condition localized in the region of the coccyx. In most cases a traumatic etiology is present. In the idiopathic form other causes such as infections and tumor have to be excluded. Coccygodynia can also be the result of pain referred from visceral structures due to conditions such as disorders of the rectum, the colon sigmoideum, and the urogenital system. In case of a traumatic etiology the diagnosis is made based on the typical medical history whereby the pain is provoked by prolonged sitting and cycling. Lateral images of the coccyx are always indicated. The same is true for manual examination of the coccyx. In case of absence of provocation of the coccygeal pain by prolonged sitting and manual examination neurological causes such as lumbar disc hernias are a possible reason for the coccygodynia. In the acute phase the first choice of treatment are NSAIDs. Treatment for patients with severe pain in the chronic phase consists of manual therapy and/or a local injection of local anesthetic and corticosteroid into the painful segment (2 C+). Other interventional treatments such as intradiscal injections, ganglion impar block, radiofrequency treatment and caudal block are advised only under study conditions (0). Coccygectomy is not recommended because of long-term moderate results and the chance of major complications.

Polymethylmetacrylate Cement Augmentation of the Coccyx (Coccygeoplasty) for Fracture: A Case Report

Background: Coccydynia is a painful condition of the sacrococcygeal region, with symptoms associated with sitting and rising from a seated position. It is frequently related to trauma and idiopathic causes, and the pain is mostly chronic. Percutaneous vertebroplasty and sacroplasty are the methods that are widely used for treating compression fractures and sacral insufficiency fractures, respectively. However, the success of polymethylmethacrylate injection in the treatment of osteoporotic coccyx fractures and coccydynia is still unknown. Case Report: A 68-year-old man was admitted to our clinic with complaints of pain in the sacrococcygeal and perianal regions. In the imaging studies, a fracture line in the fifth sacral and first coccygeal segments was observed as evidenced by a bony edema. Since the patient's pain did not improve with conservative methods, we treated him with coccygeoplasty. No complication was encountered. The day after the operation, he was discharged from the hospital with complete pain relief. The patient confirmed having no pain on the third postoperative month and so did not need any analgesics. Conclusion: Coccyceoplasty may be a good treatment option for retractable pain in patients with acute or subacute osteoporotic coccygeal fractures and coccydinia with edema.

The application of infrared thermography in the assessment of patients with coccygodynia before and after manual therapy combined with diathermy.

OBJECTIVE: This study examines the potential usefulness of a novel thermal imaging technique in the assessment of local physiologic responses before and after conservative therapies for coccygodynia. METHODS: Patients with coccygodynia were selected on the basis of detailed history taking, clinical examination, and dynamic series radiography. They underwent therapeutic modalities consisting of 6 to 8 sessions of manual medicine treatments (massage of the levators followed by Maigne's manipulative technique) and external physiotherapy (short-wave diathermy) 3 times a week for 8 weeks. We performed the assessments with numeric pain rating scale (NPRS) and infrared thermography (IRT) before treatment and at 12 weeks. RESULTS: A total of 53 patients (6 males and 47 females) ranging from 18 to 71 years of age and clinically diagnosed with coccygodynia received the full course of therapy and assessments. There were significant differences in both NPRS and surface temperature obtained by IRT in the 12-week follow-up (P < .05). The correlation between NPRS improvement and temperature decrement was significantly high (r = 0.67, P < .01). CONCLUSIONS: The study shows that IRT can objectively show the decrement of surface temperatures correlating with changes in subjective pain intensity after treatment of coccygodynia. With the advantages of being painless, noninvasive, and easy to repeat, IRT appears to be useful as a quantifiable tool for monitoring the dynamics of the disease activity in coccygodynia.

Paracoccygeal corkscrew approach to ganglion impar injections for tailbone pain.

A new technique for performing nerve blocks of the ganglion impar (ganglion Walther) is presented. These injections have been reported to relieve coccydynia (tailbone pain), as well as other malignant and nonmalignant pelvic pain syndromes. A variety of techniques have been previously described for blocking this sympathetic nerve ganglion, which is located in the retrorectal space just anterior to the upper coccygeal segments. Prior techniques have included approaches through the anococcygeal ligament, through the sacrococcygeal joint, and through intracoccygeal joint spaces. This article presents a new, paracoccygeal approach whereby the needle is inserted alongside the coccyx and the needle is guided through three discrete steps with a rotating or corkscrew trajectory. Compared with some of the previously published techniques, this paracoccygeal corkscrew approach has multiple potential benefits, including ease of fluoroscopic guidance using the lateral view, ability to easily use a stylet for the spinal needle, and use of a shorter, thinner needle. While no single technique works best for all patients and each technique has potential advantages and disadvantages, this new technique adds to the available options.

Platelet-rich plasma for the treatment of coccydynia: a case report and review of regenerative medicine for coccydynia.

Aim: To describe the successful treatment of coccydynia using ultrasound-guided injection of platelet-rich plasma. Setting: Outpatient orthopedic practice. Patient: 17-year-old female with BMI of 42.6. Case description: The patient presented with 6 months of nontraumatic coccygeal pain exacerbated by sitting. Physical exam was significant for point-tenderness over the sacral hiatus and coccyx. A corticosteroid injection around the sacrococcygeal ligament was administered with immediate resolution of her pain following the injection with the anesthetic. The patient reported significant pain relief for 1 week. The superficial sacrococcygeal ligament was then treated with a platelet-rich plasma injection under US guidance. Results: The patient reported a 70% improvement in pain and sitting tolerance at 6 weeks. By 6 months post injection, her pain was 100% resolved, and she remained pain free at the 12-month follow-up. Conclusion: Platelet-rich plasma may be considered as a treatment option in patients with refractory coccydynia.

Coccydynia - could age, trauma and body mass index be independent prognostic factors for outcomes of intervention?

Introduction The aetiology of coccydynia can be multifactorial, with several associated factors such as obesity, female gender and low mood. The long-term results of operative interventions, such as manipulation under anaesthesia and coccygectomy are variable, ranging from 63-90%. Materials and methods Our aim was to identify whether age, trauma and body mass index (BMI) were independent prognostic factors in coccydynia treatment. All patients who presented to the Royal Derby Hospital with a primary diagnosis of coccydynia between January 2011 and January 2015 who had injections, manipulation under anaesthesia or coccygectomy were included. We used patient-reported satisfaction score as the primary outcome measure. We hypothesised that patients with preceding history of trauma and with high BMI (> 25) would be less satisfied. We divided patient BMI into four groups, following World Health Organization guidelines: group A (18.5-24.9), group B (25-29.9), group C (30-39.9) and group D (> 40). Results A total of 748 patients were diagnosed with coccydynia. Of these, 201 patients had 381 injections, 40 had 98 manipulations under anaesthesia and 9 had coccygectomy. Mean age was 46.4 years; 26% of patients had trauma to the coccyx. The mean time to follow-up was 7.3 months. We found a statistically significant difference (P = 0.03) between satisfaction scores in groups B and D. Patients who had trauma improved significantly (P = 0.04). The odds ratio calculation of coccygectomy and BMI revealed a higher risk of coccygectomy in Group A. Discussion This is the first study to establish BMI and trauma as independent prognostic factors for coccydynia treatment. Our hypothesis that patients with higher BMI would have lower satisfaction levels has been proven true.

Coccygeal movement: assessment with dynamic MRI.

PURPOSE: Chronic coccygodynia is a difficult problem diagnostically and therapeutically. Moreover, there is no deep knowledge especially in the field of imaging of chronic coccygodynia. In this study several possible measurements are proposed, which all are able to demonstrate coccygeal movement during defecation, in order to assess coccygeal mobility using dynamic MRI during maximum contraction and during straining-evacuation. MATERIALS AND METHODS: A dynamic MRI study of the pelvic floor was performed in 112 patients. Five methods of measurement were assessed. Coccygeal movements were determined through the evaluation of three angles pair and two different distances measured during the phase of maximum contraction and during the phase of straining-evacuation. Results were compared according to age, sex, parity and experience of minor trauma. No patient included in the study had coccygodynia. Measurements taken by two radiologist were compared to determine interobserver agreement. RESULTS: The maximum measurement values of the two distances are homogeneous, between 9 and 9.4mm. The maximum measurement values of the three angles showed a difference that is between 21 degrees and 38 degrees . Two of three angles showed a major measurement values in the funtional texts. In only one patient the coccyx was not mobile. CONCLUSION: Our dynamic MRI study indicates that the coccyx is mobile during defecation and that it is possible to demonstrate coccygeal excursions by assessing the difference between its positions at maximum contraction and during straining-evacuation. The measurement methods used in this study for evaluating coccygeal movements resulted in variably sized observed differences, but all yielded statistically significant results in demonstrating coccygeal excursion. Among the five measurement methods, two resulted in the largest differences. Our data indicate no correlation between coccygeal movements and age, sex, parity, minor trauma and coccygodynia.

Coccygodynia - pathogenesis, diagnostics and therapy. Review of the writing.

Coccygodynia is a problem with a small percentage (1%) of the population suffering from musculoskeletal disorders. This pain is often associated with trauma, falling on the tailbone, long cycling, or by women after childbirth. The reason for the described problem can be the actual morphological changes. Idiopathic coccygodynia causes therapeutic difficulties to specialists of many fields. Unsatisfactory treatment, including coccygectomy tends to seek new solutions. They belong to them techniques exploited in the manual therapy which in their spectrum hold: direct techniques - per rectum as well as indirect techniques taking into account distant structures of the motor organ, remaining in dense interactions with the coccygeal part. Idiopathic coccygodynia is a result perhaps from exaggerated tension the muscle of the levator ani, coccygeus and gluteus maximus as well as from irritating soft tissue structures surrounding the coccyx: of sacrococcygeum, sacrospinale, and sacrotuberale ligament. Unfortunately we can't see them in objective examinations so as: the RTG, MR or TK, therefore constitute the both diagnostic and therapeutic problem. For describing the problem a writing of the object was used both from the field of the surgery and of manual therapy. Detailed and multifaceted knowledge about causes of the described problem allows more accurately to categorize the patient to the appropriate group and helps to select the best procedure of treatment.

Progression of vertebral wedging in an asymmetrically loaded rat tail model.

STUDY DESIGN: A rat tail model was used to test the hypothesis that angulation and asymmetric axial compressive loading would lead to vertebral wedging because of asymmetric longitudinal growth in the physes. OBJECTIVES: To study the effect of angulation and asymmetric loading on the progression of spinal curvature in a rat tail model. SUMMARY OF BACKGROUND DATA: Large idiopathic scoliotic curves in children with significant growth remaining are the curves most likely to progress. The mechanism of progression of skeletal deformities is thought to be controlled by the Hueter-Volkmann law, whereby additional axial compression decelerates growth, and reduced axial compression accelerates growth. It has been hypothesized that spinal curvature leads to asymmetric loading transversely along the vertebral growth plate, causing progressive vertebral wedging by means of a vicious cycle. METHODS: Two 32-mm diameter external ring fixators were glued to 0.7-mm pins that had been inserted percutaneously through the eighth and 10th caudal vertebra of 10 6-week-old Sprague-Dawley rats. Calibrated springs and 15 degrees wedges, mounted on stainless steel threaded rods passing through holes distributed around the rings, imposed a 30 degrees Cobb angle and axially compressed the instrumented vertebrae. Fluorochrome labels and radiographs were used to document the progression of vertebral wedging. RESULTS: The wedging initially was entirely in the intervertebral discs, but by 6 weeks the wedging of the discs and vertebrae were approximately equal. Fluorochrome labeling confirmed that the vertebral wedging resulted from asymmetric growth in the physes. CONCLUSIONS: This study shows that vertebrae, when asymmetrically loaded, become wedged. This is consistent with the concept of mechanically provoked progression of scoliotic deformities according to the Hueter-Volkmann law.

Comparison of three manual coccydynia treatments: a pilot study.

STUDY DESIGN: A prospective pilot study with independent assessment and a 2-year follow-up period was conducted. OBJECTIVES: To compare and assess the efficacy of three manual coccydynia treatments, and to identify factors predictive of a good outcome. SUMMARY OF BACKGROUND DATA: Various manual medicine treatments have been described in the literature. In an open study, the addition of manipulation to injection treatment produced a 25% increase in satisfactory results. Dynamic radiographs of the coccyx allow breakdown of coccydynia into four etiologic groups based on coccygeal mobility: luxation, hypermobility, immobility, and normal mobility. These groups may respond differently to manual treatments. METHODS: The patients were randomized into three groups, each of which received three to four sessions of a different treatment: levator anus massage, joint mobilization, or mild levator stretch. Assessment with a visual analog scale was performed by an independent observer at 7 days, 30 days, 6 months, and 2 years. RESULTS: The results of the manual treatments were satisfactory for 25.7% of the cases at 6 months, and for 24.3% of the cases at 2 years. The results varied with the cause of the coccydynia. The patients with an immobile coccyx had the poorest results, whereas those with a normally mobile coccyx fared the best. The patients with luxation or hypermobility had results somewhere between these two rates. Levator anus massage and stretch were more effective than joint mobilization, which worked only for patients with a normally mobile coccyx. Pain when patients stood up from sitting and excessive levator tone were associated with a good outcome. However, none of the results was significant because of the low success rate associated with manual treatment. CONCLUSIONS: There is a need for a placebo-controlled study to establish conclusively whether manual treatments are effective. This placebo must be an external treatment. A sample size of 190 patients would be required for 80% confidence in detecting a difference.

Causes and mechanisms of common coccydynia: role of body mass index and coccygeal trauma.

STUDY DESIGN: A total of 208 consecutive coccydynia patients were examined with the same clinical and radiologic protocol. OBJECTIVES: To study radiographic coccygeal lesions in the sitting position, to elucidate the influence of body mass index on the different lesions, and to establish the effect of coccygeal trauma. SUMMARY OF BACKGROUND DATA: A protocol comparing standing radiographs and radiographs subsequently taken in the painful sitting position in coccydynia patients and in controls has shown two culprit lesions: posterior luxation and hypermobility. Obesity and a history of trauma have been identified as risk factors for luxation. METHODS: Dynamic radiographs were obtained. The body mass index was compared with the coccygeal angle of incidence, sagittal rotation of the pelvis when sitting down, and the presence and time of previous trauma. The patients with the newly described lesions were examined after an anesthetic block under fluoroscopic guidance. RESULTS: Two new coccygeal lesions are described (anterior luxation and spicules). Obesity was found to be a risk factor. The body mass index determines the way a subject sits down, and lesion patterns were different in obese, normal-weight, and thin patients (posterior luxation: 51%, 15.2%, 3.7%; hypermobility: 26.5%, 30.3%, 14.8%; spicules: 2%, 15.9%, 29.6%; normal: 16.3%, 32.6%, 48.1%, respectively; P < 0.0001). Trauma affected the type of lesion only if it was recent (<1 month before the onset of coccydynia), in which case the instability rate increased from 55.6% to 77.1%. Backward-moving coccyges were at greatest risk of trauma. CONCLUSIONS: This protocol allows identification of the culprit lesion in 69.2% of cases. The body mass index determines the causative lesion, as does trauma sustained within the month preceding the onset of the pain.

A treatment and outcomes analysis of patients with coccydynia.

BACKGROUND CONTEXT: Coccydynia is a painful condition of the terminal portion of the spine often resulting from direct trauma, childbirth or unknown etiology. This is a relatively rare condition with no universally accepted treatment protocol. PURPOSE: To more clearly determine the optimal treatment for patients with coccydynia and to assess the outcomes after conservative and surgical therapy. STUDY DESIGN: Retrospective review of outcomes of all patients presenting with symptoms of coccydynia during a 5-year period. PATIENT SAMPLE: Thirty-two patients presented to an orthopedic spine surgeon during a 5-year period with symptoms of coccydynia. OUTCOME MEASURES: Patients completed visual analog pain scales (VAS) and the Oswestry (OSW) functional capacity index. METHODS: Of the 32 patients in the study, 4 (13%) were treated with nonsteroidal anti-inflammatory drugs (NSAIDs) alone, 17 (53%) were treated with NSAIDs followed by local injections and 11 (34%) underwent coccygectomy after failure of NSAIDs and local injections. Patients completed VAS and OSW forms. Pain drawings were also completed. RESULTS: Patients undergoing surgery had significantly greater pretreatment VAS scores (8.3 vs 5.4, p=.002). Surgical patients also had greater OSW scores, but not significantly (36.6 vs 24.2, p=.223). Marked improvement was reported by 9 of 11 (82%) surgical patients. Three of 11 (27%) surgical patients developed wound infections and 1 (9%) wound dehiscence. All infections resolved following irrigation and debridement and a short course of oral antibiotics. CONCLUSIONS: Patients with coccydynia should be managed conservatively when possible. Treatment should include NSAIDs and local steroid injections. Patients will often require repeat injections over time. Surgery can offer reasonable results for patients failing conservative treatment, but they should be warned of the high rate of infection.

Clinical and radiological differences between traumatic and idiopathic coccygodynia.

Several reports of coccygodynia have been confined to the causes, the methods of treatment, and the methods of radiological examination. As far as we know, there has been no previous study about the objective measurement of the coccyx. The purpose of this study was to find the possible cause of idiopathic coccygodynia by comparing the clinical and radiological differences between traumatic and idiopathic coccygodynia by innovative objective clinical and radiological measurements. Thirty-two patients with coccygodynia were evaluated retrospectively. We divided the patients into two groups. Group 1 consisted of 19 patients with traumatic coccygodynia and group 2 consisted of 13 patients with idiopathic coccygodynia. We reviewed medical records and checked age, sex distribution, symptoms, and treatment outcome in each group. We also reviewed coccyx AP and lateral views of plain radiological film and measured the number of coccyx segments and the intercoccygeal angle in each group. The intercoccygeal angle devised by the authors was defined as the angle between the first and last segment of the coccyx. We also checked the intercoccygeal angle in a normal control group, which consisted of 18 women and 2 men, to observe the reference value of the intercoccygeal angle. The outcome of treatment was assessed by a visual analogue scale based on the pain score. Statistical analysis was done with Mann-Whitney U test and Chi-square test. Group 1 consisted of 1 male and 18 female patients, while group 2 consisted of 2 male and 11 female patients. There were no statistically significant differences between the traumatic and idiopathic coccygodynia groups in terms of age (38.7 years versus 36.5 years), male/female sex ratio (1/18 versus 2/11), and the number of coccyx segments (2.9 versus 2.7). There were significant differences between the traumatic and idiopathic coccygodynia groups in terms of the pain score (pain on sitting: 82 versus 47, pain on defecation: 39 versus 87), the intercoccygeal angle (47.9 degree versus 72.2 degrees), and the satisfactory outcome of conservative treatment (47.4% versus 92.3%). The reference value of the intercoccygeal angle in the normal control group was 52.3 degrees, which was significantly different from that of the idiopathic group. In conclusion, the intercoccygeal angle of the idiopathic coccygodynia group was greater than that of the traumatic group and normal control group. Based on the results of this study, the increased intercoccygeal angle can be considered a possible cause of idiopathic coccygodynia. The intercoccygeal angle was a useful radiological measurement to evaluate the forward angulation deformity of the coccyx.