Imaging study of coccygeal morphology in adolescent idiopathic scoliosis.

The correlation between scoliosis and sagittal curvature of the cervical, thoracic, and lumbar spine have already been reported in previous studies. However, as a part of the spine, the change in coccygeal morphology in AIS patients has not yet been studied. In this study, a retrospective analysis was performed on 400 patients who were divided into a non-scoliotic group (206 patients) and an AIS group (194 patients). The Postacchini coccygeal radiological classification that was modified by Nathan was used to observe and compare the sagittal coccygeal morphology between the two groups. The results showed that the non-scoliotic group had the highest percentage (52.4%) of patients with type I and the lowest (3.4%) proportion of patients with type V; moreover, the AIS group had the highest percentage (69.1%) of patients with type I and the lowest (1.5%) proportion of patients with type V. The coccygeal morphology was significantly different between the non-scoliotic group and the AIS group (P = 0.001). No significant differences in coccygeal morphology were found between the males and females in the two groups (mild and moderate scoliosis and different segmental scoliosis). In addition, a significant correlation between coccygeal morphology and scoliosis (P = 0.035) was found. In conclusion, coccygeal morphology significantly differs between AIS patients and non-scoliotic adolescents. There was a smaller proportion of patients with a type I coccyx and a larger proportion of patients with a type II or type III coccyx in the AIS group than in the non-scoliotic group. In other words, the presence of a more pronounced coccygeal curve in AIS patients may be caused by an incorrect sitting position and an imbalance in the contraction of the pelvic muscles. It should be further studied whether correcting the sitting position and muscular imbalances could change coccygeal morphology and subsequently affect the development of AIS.

The overlooked symptom of coccydynia: evaluation of sacrococcygeal morphologic and morphometric findings.

BACKGROUND: Coccydynia is one of the most overlooked symptoms in daily clinical practice. Definitions for radiologic evaluation are controversial. OBJECTIVES: We aimed to compare the morphology and morphometric measurements of the sacrococcygeal region with those of a healthy population to support radiologic decision-making. MATERIALS AND METHODS: In total, 26 traumatic and 50 idiopathic cases of coccydynia as well as 74 healthy control cases were retrospectively compared. The morphologic type of the coccyx, the presence of fusion, and the number of coccygeal segments were evaluated in both groups. Morphometric parameters such as sacrococcygeal angle (SCA), sacrococcygeal joint angle (SCJA), intercoccygeal angle (ICA), sacral slope (SS), coccyx curved length (CCL), sacrum curved length (SCL), coccyx length (CL), sacrum length (SL), and sacrococcygeal total length (SCTL) were investigated. RESULTS: Significant differences were found between the coccydynia group and the healthy control group in morphologic parameters such as female gender, coccyx segment, coccyx morphology, presence of sacrococcygeal joint, and segment of sacrococcygeal joint fusion (p < 0.05). In morphologic measurements, SCJA, SCL, SL, coccyx and sacrum curvature indexes were significantly increased (p < 0.05). No significant difference was found in the morphologic and morphometric parameters evaluated when compared with the duration of coccydynia (p > 0.05). CONCLUSION: An increase in the SCJA, SCL, SL, SCI, and coccyx curvature index measurements predisposes to coccydynia. It would be more accurate to perform radiological evaluation by familiarization with these morphologic and morphometric parameters.

Coccygeoplasty: preliminary experience with this new alternative treatment of refractory coccydynia in patients with coccyx hypermobility.

BACKGROUND: Coccydynia has many causes, including fracture, subluxation, and hypermobility of sacrococcygeal segments. Existing treatments are limited in their effectiveness. Coccygeoplasty (CP) is a relatively new, minimally invasive treatment that appears to address this difficult clinical challenge. OBJECTIVE: To describe clinical results at the time of the procedure and at 3- and 12-months' follow-up of patients with coccydynia related to subluxation and coccyx hypermobility treated with the CP technique. Additionally, to determine if there is any correlation between the final imaging and clinical results at 3- and 12-months' follow-up. METHODS: A prospectively maintained database was used, and all patients who underwent CP for chronic coccydynia between January 2005 and October 2018 were retrospectively reviewed. All the patients had painful hypermobility (greater than 25°) with anterior flexion confirmed on radiological imaging. Alternative causes of coccydynia were excluded using CT and MRI. Procedures were performed under local anesthesia with combined fluoroscopic and CT guidance. Clinical follow-up was performed at two time points: 3 and 12 months after treatment using the Visual Analogue Scale (VAS). RESULTS: Twelve patients were treated in a single center. No procedural complications occurred. At 3- and 12-months' follow-up, the majority (75%) of patients had significantly lower VAS scores than at baseline, with mean changes of 3.5 and 4.9, respectively. There was no pain recurrence at 12 months and just one patient had no improvement of the pain. Follow-up CT images confirmed fixation of the sacrococcygeal bone segments in nine patients; however, no correlation was found between final imaging results and clinical outcome (p=0.1). CONCLUSIONS: Patients with refractory painful coccyx subluxation and hypermobility undergoing CP have a favorable clinical response at 3- and 12-months' follow-up. Further studies are required to validate this technique and to identify predictors of treatment response. Coccygeoplasty may be considered a reasonable alternative to coccygectomy.

Novel approach for pericapsular radiofrequency ablation of sacrococcygeal junction for patients with coccydynia.

INTRODUCTION: Coccydynia is a multifactorial complex clinical challenge. A multimodal approach with both conservative measures and procedural interventions is often recommended. We described a novel approach of radiofrequency (RF) ablation for the management of coccydynia. METHODS: Three patients with known history of coccydynia refractory to conservative therapy were referred to our clinic. All received different types of RF ablation before: one with anterior bipolar lesion with no analgesia benefit, one with posterior stripped lesion with good benefit but only after 8 weeks of pain flare and one received anterior monopolar lesion with 50% pain reduction for 2-3 months. All subjects underwent a novel RF ablation to the anterior surface of the sacrococcygeal and intercoccygeal joints with two bipolar lesions using multi-tined needles under fluoroscopy guidance. One bipolar lesion was between two needles: one in the sacrococcygeal and another in the intercoccygeal (between first and second coccyx) joints. Another bipolar lesion was between needles on both side of the sacrococcygeal joint. RESULTS: All experienced at least 65% pain relief for 6 months. The sitting endurance increased from less than 5 min to an average of 70 min. No adverse effect was observed in two and in the patient who used to have pain flare after lesioning, the pain flare lasted only for 2 weeks. DISCUSSION: The configuration of the two bipolar lesions with multi-tined needles in this case series stimulates the thinking of new approach for the ablation technique for pain from coccyx. Further prospective large case cohort study is needed.

A novel radiological classification for displaced os coccyx: the Benditz-König classification.

BACKGROUND: Treatment of coccygodynia is still a challenging entity. Clear surgical selection criteria are still lacking. The aim of the investigation was to establish a novel radiological classification for surgical decision-making in coccygodynia cases. MATERIAL AND METHODS: Retrospective analysis of standing and sitting X-rays of coccygodynia patients referred to a single centre from 2018 to 2020. The sacro-coccygeal angle (SCA), the intra-coccygeal angle (ICA) and the difference of the intervertebral disc height (∆IDH) were measured. All coccyges were distributed in subtypes and correlated with the patients' treatment. RESULTS: In total, 138 patients (female/male: 103/35) with a mean age of 45.6 ± 15.4 years were included in the study. In total, 49 patients underwent coccygectomy. Four different subtypes of displaced coccyges were identified: Type I with a non-segmented coccyx, anterior pivot, increased SCA and ICA from standing to sitting, ∆IDH = 1.0 ± 1.5 mm. Type II with a multisegmented coccyx, anterior pivot, increased SCA and ICA standing/sitting, ∆IDH = 1.1 ± 1.6 mm. Type III showed a posterior pivoted coccyx, negative SCA and ICA, ∆IDH = 0.6 ± 1.6 mm. Type IV is characterized by an anterior-posterior dissociation of the tail bone with a positive SCA, and the ICA shifted from a posterior to an anterior orientation. ∆IDH was - 0.6 ± 1.8 mm. CONCLUSION: The presented radiological classification could help to facilitate the surgical decision-making for patients with displaced os coccyx. In addition, lateral and sitting X-rays were easy to perform and did not need unnecessary ionizing radiation like in CT scans and were more cost-effective than MRI investigations. The subtypes III and especially IV were more likely leading to surgery.

Three-dimensional evaluation of the coccyx movement between supine and standing positions using conventional and upright computed tomography imaging.

Currently, no three-dimensional reference data exist for the normal coccyx in the standing position on computed tomography (CT); however, this information could have utility for evaluating patients with coccydynia and pelvic floor dysfunction. Thus, we aimed to compare coccygeal parameters in the standing versus supine positions using upright and supine CT and evaluate the effects of sex, age, and body mass index (BMI) on coccygeal movement. Thirty-two healthy volunteers underwent both upright (standing position) and conventional (supine position) CT examinations. In the standing position, the coccyx became significantly longer and straighter, with the tip of the coccyx moving backward and downward (all p < 0.001). Additionally, the coccygeal straight length (standing/supine, 37.8 ± 7.1/35.7 ± 7.0 mm) and sacrococcygeal straight length (standing/supine, 131.7 ± 11.2/125.0 ± 10.7 mm) were significantly longer in the standing position. The sacrococcygeal angle (standing/supine, 115.0 ± 10.6/105.0 ± 12.5°) was significantly larger, while the lumbosacral angle (standing/supine, 21.1 ± 5.9/25.0 ± 4.9°) was significantly smaller. The migration length of the tip of the coccyx (mean, 7.9 mm) exhibited a moderate correlation with BMI (r = 0.42, p = 0.0163). Our results may provide important clues regarding the pathogenesis of coccydynia and pelvic floor dysfunction.

Application of subject-specific adaptive mechanical loading for bone healing in a mouse tail vertebral defect.

Methods to repair bone defects arising from trauma, resection, or disease, continue to be sought after. Cyclic mechanical loading is well established to influence bone (re)modelling activity, in which bone formation and resorption are correlated to micro-scale strain. Based on this, the application of mechanical stimulation across a bone defect could improve healing. However, if ignoring the mechanical integrity of defected bone, loading regimes have a high potential to either cause damage or be ineffective. This study explores real-time finite element (rtFE) methods that use three-dimensional structural analyses from micro-computed tomography images to estimate effective peak cyclic loads in a subject-specific and time-dependent manner. It demonstrates the concept in a cyclically loaded mouse caudal vertebral bone defect model. Using rtFE analysis combined with adaptive mechanical loading, mouse bone healing was significantly improved over non-loaded controls, with no incidence of vertebral fractures. Such rtFE-driven adaptive loading regimes demonstrated here could be relevant to clinical bone defect healing scenarios, where mechanical loading can become patient-specific and more efficacious. This is achieved by accounting for initial bone defect conditions and spatio-temporal healing, both being factors that are always unique to the patient.

Coccygodynia Due to a Sacrococcygeal Anomaly: A Rare Cause of Constipation.

ABSTRACT: We report a case of an uncommon sacrococcygeal anomaly in a healthy girl initially presenting to the emergency department with coccygodynia and a past history of longstanding constipation. The clinical evolution was satisfactory once the bony anomaly was removed (coccygectomy). This unusual case exemplifies the importance of the medical history and physical examination to make an accurate diagnosis. An inadequate intervention may result in persistent pain, worsening longstanding constipation, and psychosocial and medical consequences.

Normal Preoperative Images Do Not Indicate a Poor Outcome of Surgery for Coccydynia.

STUDY DESIGN: This is a retrospective cohort study. OBJECTIVE: To evaluate the long-term outcomes after surgery for refractory coccygodynia in patients with normal imaging studies compared with patients where imaging shows an anomaly. SUMMARY OF BACKGROUND DATA: Patients with coccydynia who do not respond to conservative treatment will often profit from coccygectomy. Most surgeons employ plain radiographs or magnetic resonance imaging (MRI) in their preoperative work-up. These will often show anomalies, but in some cases they do not. We investigated whether these patients do less well than those with abnormal images. METHODS: We operated on 184 patients with coccydynia during a 7-year period and 171 (93%) responded to follow-up questionnaires after 37 (range: 12-85) months. Images of 33 patients were normal and 138 showed some coccygeal pathology. Surgery was considered to have been unsuccessful when respondents stated at review that they were somewhat better, unchanged, or worse. RESULTS: There were no clinically or statistically significant differences in outcome between the groups. Surgery was unsuccessful in 24% of patients with normal images and in 32% among those with abnormal images. The median pain scores (0-10) during the week before review were two (interquartile range [IQR]: 0-3) and one (IQR: 1-5) in the two groups respectively. Similar proportions in the two groups stated that they would not have consented to surgery if they had known the outcome in advance. CONCLUSION: Patients with severe coccydynia who have not responded to conservative treatment should not be denied surgery only because their radiographs or MRI studies look normal. LEVEL OF EVIDENCE: 4.

Risk of rectal puncture due to needle entry into the presacral space: Importance of measuring the distance between the rectum and sacrococcyx, and the thickness of the sacrococcyx.

During ganglion impar block, the needle may approach the presacral space and the sacrum may be penetrated during caudal anesthesia. Because the rectum is in front of the sacrococcyx and is thus at risk for puncture, it is important to determine the distance between the sacrococcyx and rectum, as well as the thickness of the sacrococcyx.Computed tomography was used to measure the distance between the rectum and sacrococcyx, as well as the thickness of the sacrococcyx. The distances between the coccyx and rectum, sacrococcygeal joint and rectum, sacral level 5 ('sacrum 5') and rectum, and 'sacrum 4 to 5 junction' and rectum were measured. The results were compared based on the presence or absence of stools in the rectum. The thickness of the sacrococcyx was measured at the sacrum 4 to 5 junction and sacrococcygeal joint.In total, 1264 patients were included in this study. All distances were less than 1 mm in both males and females, with the exception of the distance between the coccyx and rectum in males. In both males and females, there was no significant difference in distance between the sacrococcyx and rectum according to the presence or absence of feces in the rectum, but there was a difference in the distance between sacrum 5 and the rectum in males (P = .048). Several male and female patients showed thicknesses of less than 5 mm at the sacrococcygeal joint.Some patients have a distance of less than 1 mm between the sacrum and rectum. Practitioners should exercise caution when applying a needle to the presacral space. If the sacrum is accidentally penetrated during caudal block, rectum puncture cannot be ruled out. Excretion of feces does not influence the distance between the sacrococcyx and rectum in females.

Caudal Regression Syndrome (Spinal Thoraco-lumbo-sacro-coccygeal Agenesis).

This is a case report of a 2-year-old male who presented with walking disability and sphincter incontinence since birth. His mother has diabetes mellitus. The patient had a normal mental function, and his lower extremities were hypoplastic and akinetic. Spinal neuroimaging investigations revealed agenesis of the spinal column below T9 vertebral level with abrupt termination of the spinal cord at the T6 vertebral level. With this severe caudal regression syndrome (CauReS), cardiac, anorectal, urologic, and orthopedic consultations were made looking for other potential associated malformations. Unfortunately, no neurosurgical indication was suggested. CauReS is a rare congenital disorder in which there is abnormal fetal development of the lower spine and hypoplasia of the lower extremities. Neurosurgically, there are no clear guidelines to follow for patients with CauReS. Sometimes, surgical spinal cord untethering may be indicated in some selected patients to improve neurologic function.

Imaging Coccygeal Trauma and Coccydynia.

The coccygeal region has complex anatomy, much of which may contribute to or be the cause of coccyx region pain (coccydynia). This anatomy is well depicted at imaging, and management is often dictated by what structures are involved. Coccydynia is a common condition that is known to be difficult to evaluate and treat. However, imaging can aid in determining potential causes of pain to help guide management. Commonly, coccydynia (coccygodynia) occurs after trauma and appears with normal imaging features at static neutral radiography, but dynamic imaging with standing and seated lateral radiography may reveal pathologic coccygeal motion that is predictive of pain. In addition, several findings seen at cross-sectional imaging in patients with coccydynia can point to a source of pain that may be subtle and easily overlooked. Radiology can also offer a role in management of coccygeal region pain with image-guided pain management procedures such as ganglion impar block. In addition to mechanical coccyx pain, a host of other conditions involving the sacrococcygeal region may cause coccydynia, which are well depicted at imaging. These include neoplasm, infection, crystal deposition, and cystic formations such as pilonidal cyst. The authors review a variety of coccydynia causes, their respective imaging features, and common management strategies.©RSNA, 2020.

Sacrococcygeal teratoma with intraspinal extension: A case series and review of literature.

BACKGROUND: Sacrococcygeal teratoma (SCT) is the most common teratoma in neonates and arises from the coccyx. SCT with intraspinal invasion is extremely rare and only reported in a few cases. METHODS: 37 patients with SCT were identified at our institution between 2000 and 2018. Three of these patients had SCT with intraspinal extension. A literature review for intraspinal extension associated with SCT, including mode of diagnosis, presentation, surgical approach and neurological sequelae, between 1993 and 2018 was also conducted. RESULTS: The authors report three cases of infants who were antenatally and/or postnatally diagnosed with a sacrococcygeal teratoma extending into the spinal canal. We illustrate the challenges of accurate diagnosis and therapeutic management. Postnatal magnet resonance imaging (MRI) was the best method to define spinal anatomy and extension of the tumors prior to surgery. Management with a multidisciplinary team approach including neuroradiology, neurosurgery and general surgery was used in our two most recent patients. The literature review yielded 6 cases of SCT with intraspinal extension. CONCLUSION: Intraspinal extension in SCT is rare but should be excluded at birth before attempting any resection. In case of positive spinal invasion on Ultrasonography (US), MRI is essential to plan for surgery and possible laminectomy to be able to perform a radical resection of this congenital tumor. We recommend this multidisciplinary approach. LEVEL OF EVIDENCE: Level IV.

Classification of fractures of the coccyx from a series of 104 patients.

PURPOSE: To describe a classification of fractures of the coccyx, according to their mechanism. METHODS: A series of 104 consecutive patients with a fracture of the coccyx was studied. The mechanism, level, characteristics of the fracture line and complications were recorded. RESULTS: Three mechanisms are proposed to describe these fractures: flexion, compression and extension (types 1, 2 and 3, respectively). Flexion fractures (38 cases) involved the upper coccyx in 35 cases, and in 3 cases with a perineal trauma, it was the lower coccyx; compression fractures (24 cases) involved the middle coccyx and occurred only when Co2 was square or cuneiform and Co3 was long and straight, hence a nutcracker mechanism; four patients were adolescents with a compression of the sacrum extremity and were labeled adolescent compression fracture of S5 (type 2b); extension fractures (38 cases) were obstetrical and involved the lower coccyx; their key feature was a progressive separation of the fragments with time. Flexion fractures usually healed spontaneously, but an associated intermittent luxation was possible. Nutcracker and obstetrical fractures were instable in their majority. CONCLUSIONS: For the first time, a classification of fractures of the coccyx is presented. Each type exhibits specific features. This should help the clinician in the management of these patients. These slides can be retrieved under Electronic Supplementary Material.

Conus infarction after non-guided transcoccygeal ganglion impar block using particulate steroid for chronic coccydynia.

Introduction: Ganglion impar block (GIB) is a well-recognised treatment for chronic coccydynia. Several side effects have previously been described with this procedure, including transient motor dysfunction, bowel, bladder, and sexual dysfunction, neuritis, rectal perforation, impingement of the sciatic nerve, cauda equina syndrome, and infection. Case presentation: We describe the first report of imaging-documented conus infarction after an unguided-GIB performed in theatre using particulate steroids for a 17-year-old patient with coccydynia. Immediately post-GIB, patient developed transient neurological deficits in her lower limbs of inability to mobilise her legs that lasted for 24 h. These include back and leg pain, decreased power and movement, increased tone, brisk reflexes, reduced light touch sensation and proprioception of legs up to the T10 level. Urgent MRI spine showed intramedullary hyperintense signal within the conus and mild restricted diffusion on the distal cord and conus, suggestive of an acute conus infarction. On follow-up, the GIB did not result in symptom improvement of coccydynia and there was persistent altered sensation of her legs. Discussion: Various approaches of ganglion impar block have been described and performed in the past with different imaging techniques and injectants. A few cases of unusual neurological complications have been reported with the use of epidural steroid injections and ganglion impar block. Clinicians should be aware of the possible neurological complications following ganglion impar blocks and the risk of inadvertent intravascular injection of particulate steroids can potentially to be minimised by using imaging guidance.

Sex estimation from sacrum and coccyx with discriminant analyses and neural networks in an equally distributed population by age and sex.

Sex estimation is an essential step in the process of the identification of the skeletal remains in forensic anthropology since it reduces the number of possible matches by half. In this study, sex estimation with 21 sacral and coccygeal metric parameters obtained from Computerized Tomography images of a Turkish population which consists of 480 patients that are equalized according to their sexes and ages, is performed. Univariate discriminant analysis, linear discriminant function analysis, stepwise discriminant function analysis, and multilayer perceptron neural networks are used in this study. A maximum of 67.1% accuracy for univariate discriminant analysis, 82.5% for linear discriminant function analysis, 78.8% for stepwise discriminant function analysis, and 86.3% for multilayer perceptron neural networks, were achieved. Although it does not reach an acceptable accuracy rate of 95% or more for sacrum and coccyx, sex estimation with neural networks is a promising field of research in corpses where identification is otherwise not possible, and further studies with other bones and with new techniques might give useful information.

Morphological evaluation of the coccyx with multidetector computed tomography.

PURPOSE: This study aims to evaluate the morphology of the coccyx in adults with multidetector computed tomography and to contribute to the classification of the coccyx using intercoccygeal and sacrococcygeal angle measurements. METHODS: The pelvic computed tomography images of 224 patients were retrospectively evaluated. The multiplanar reconstruction and 3D volume rendering images of the coccyx were obtained from all patients at sagittal and coronal planes. The morphology of the coccyx, number of bone segments, the presence of scoliosis, and presence of sacrococcygeal and intercoccygeal fusion were evaluated. After the measurement of coccygeal length, width, and thickness, intercoccygeal and sacrococcygeal angles were also calculated in all patients. RESULTS: The morphological classification showed that 136 patients (60.7%) had type 1, 65 patients (29%) had type 2, and 17 patients (7.6%) had type 3 coccyx. The intercoccygeal angle was zero degree in five patients (type 0) and one patient had retroverted coccyx (type 5). The coccyx had four segments in 155 patients (69.2%), three segments in 52 patients (23.2%), five segments in 15 patients (6.7%), two segments in one patient (0.4%), and one segment in one patient (0.4%). CONCLUSION: We determined patients with an intercoccygeal angle of zero degree, which is not mentioned in the literature before, and we propose to use the term "type 0" for these patients in the classification of coccyx. The coccygeal measurements and classification will be instructive for the radiologists and have a guiding role for the future studies.