Evaluation of coccygeal bone variability, intercoccygeal and lumbo-sacral angles in asymptomatic patients in multislice computed tomography

The design of a family of parametric anatomically-based compliant buttock models to evaluate wheelchair cushion performance

The evaluation of wheelchair cushion performance is of interest to a variety of stakeholders, including standards organizations, cushion manufacturers, clinicians, users and payers. The objective of this project was to develop a family of compliant buttock models that are based upon the anatomical parameters of persons with varying body sizes. The models are parametrically designed so can be scaled to evaluate different sized cushions. This paper will detail the designs, describe the anatomical basis for the design and provide the rationale for the design decisions. The manuscript also serves a secondary purpose to illustrate how anthropometric data can be applied to the design of anatomical phantoms that reflect both soft tissue and skeletal anthropometry. Supplemental material includes greater detail and the full CAD files and model fabrication instructions are available in an open access repository for persons who wish to fabricate the models.

Does Sacrococcygeal Skeletal Morphology and Morphometry Influence Pressure Injury Formation in Adults?

GENERAL PURPOSE

To present a study that investigated sacrococcygeal skeletal structure as a possible nonmodifiable intrinsic risk factor for pressure injury and identify possible issues caused by its morphology.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will:1. Recognize the background information the authors considered when planning and conducting their study of sacrococcygeal skeletal structure as a possible pressure injury risk factor.2. Identify the characteristics of the two groups of study participants.3. Choose the results of the study clinicians may consider when implementing evidence-based practice.

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.

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.

Visualizing Tissue Strain Under the Sacrum and Coccyx in Different Supine Postures: A Case Series

OBJECTIVE

To visually assess and report the influence of supine positioning and sacrum and coccyx anatomy on tissue deformation.

METHODS

A convenience sample of three participants was scanned using MRI. All participants were scanned in a supine position with a rig oriented in a flat or horizontal position and with the torso portion of the rig elevated to 30° to simulate head-of-bed elevation. Representative images were identified to visualize and depict (1) the differences in tissue thickness and deformation in response to changes in supine positioning (0° and 30°), (2) the relative displacement of the skeleton relative to the skin during 30° incline, and (3) differences in sacrococcygeal morphology.

RESULTS

The tissue thickness under the sacrum stayed the same or increased when torsos were elevated. Skeletons were displaced relative to the skin when the rig was elevated regardless of the pelvis location. Further, in the elevated position, coccyges flexed when pelvises were placed on the elevated segment but did not flex when pelvises were placed on the horizontal segment.

CONCLUSIONS

This case series is useful in defining new areas of research that can (1) identify the deformation induced by normal and frictional forces resulting from different positions of the bed chassis, (2) assess the impact of positioning the pelvis on elevated versus horizontal segments of the bed chassis, and (3) define the association between sacral and coccyx morphology and pressure ulcer occurrence in hospitalized patients.

Magnetic Resonance Measurements of Sacrococcygeal and Intercoccygeal Angles in Normal Participants and those with Idiopathic Coccydynia

BACKGROUND

In the past, few studies have been done to objectively measure the sacrococcygeal (SC) and intercoccygeal (IC) angles in the population and in patients with coccydynia. Coccydynia is an age-old disorder, the exact incidence of which has not been determined. It is reported to be more common in females and the obese. The magnetic resonance imaging (MRI) studies done in the past have calculated the curvature indices. In this study, we used MRI to objectively measure the angles in the normal participants as well as those with idiopathic coccydynia.

MATERIALS AND METHODS

Two groups of patients were identified. Group A was "control group" of 106 normal participants and Group B comprised "study group" of ten patients suffering from idiopathic coccydynia. In all these patients, midsagittal T1-weighted MRI image acquired in supine position was used to calculate SC and IC angles. Data were analyzed, and angles were compared between the study and control groups. Statistical analysis was done with Chi-square test.

RESULTS

In the control group, the average SC and IC angles in the control group were 126.8° and 33.5°, respectively. In the study group, the average SC angle and the average IC angle turned out to be 127.1° and 43.2°, respectively. The difference between the SC angles in the control and study groups was not significant (P = 0.7), whereas the difference between the IC angles in the two groups was significant (P = 0.002).

CONCLUSIONS

From our study, we observed that the IC angle shows a decreasing trend with increasing age. In addition, increased IC angle was identified as a possible cause of idiopathic coccydynia.

Coccygeal Morphology on Multislice Computed Tomography in a Tertiary Hospital in India

Study Design

A retrospective, cross-sectional study of 213 patients who presented for abdominal computed tomography (CT) scans to assess coccygeal morphology in the Indian population.

Purpose

There have been relatively few studies of coccygeal morphology in the normal population and none in the Indian population. We aimed to estimate coccygeal morphometric parameters in the Indian population.

Overview of Literature

Coccygeal morphology has been studied in European, American, Korean, and Egyptian populations, with few differences in morphology among populations.

Methods

A retrospective analysis of 213 abdominal CT scans (114 males and 99 females; age, 7–88 years; mean age, 47.3 years) was performed to evaluate the number of coccygeal segments, coccyx type, sacrococcygeal and intercoccygeal fusion and subluxation, coccygeal spicules, sacrococcygeal straight length, and sacrococcygeal and intercoccygeal curvature angles. Results were analyzed for differences in morphology with respect to sex and coccyx type.

Results

Types I and II coccyx were the most common. Most subjects had four coccygeal vertebrae; 93 subjects (43.66%) had partial or complete sacrococcygeal fusion. Intercoccygeal fusion was common, occurring in 193 subjects. Eighteen subjects had coccygeal spicules. The mean coccygeal straight length was 33.8 mm in males and 31.5 mm in females; the mean sacrococcygeal curvature angle was 116.6° in males and 111.6° in females; the mean intercoccygeal curvature angle was 140.94° in males and 145.10° in females.

Conclusions

Type I was the most common coccyx type in our study, as in Egyptian and Western populations. The number of coccygeal vertebrae and prevalence of sacrococcygeal and intercoccygeal fusion in the Indian population were similar to those in the Western population. The mean coccygeal straight length and mean sacrococcygeal curvature angle were higher in males, whereas the intercoccygeal curvature angle was higher in females. Information on similarities and differences in coccygeal morphology between different ethnic populations could be useful in imaging and treating patients presenting with coccydynia.

Coccygeal body revisited: An immunohistochemical study using donated elderly cadavers

To describe the normal anatomy and histology of the adult coccygeal body (CB) and to discuss about the origin and function, using immunohistochemistry, we examined 29 CBs found in 32 elderly donated cadavers without macroscopic pathology in the pelvis. The CB was usually located in or near the anococcygeal ligaments. It was almost always composed of multiple masses or nodules of round glomus cells (smooth muscle actin or SMA++). However, the CB sometimes contained abundant dilated veins with scattered glomus cells. Thus, the CBs varied from the glomus cell nodule-dominant type, through an intermediate morphology with a mixture of nodules and veins, to the vein-dominant type. Each glomus cell mass was surrounded by abundant sympathetic nerves. In all specimens, we found multiple abnormal arteries, each of which carried a glomus-like cell layer around the almost -obliterated vascular lumen; as well as an SMA-negative thick arterial wall containing abundant sympathetic nerves. The ligaments around the CB are known to be under strong mechanical stress from the pelvic floor. We considered abnormal arteries containing the unique internal layer as an intermediate between a normal muscular artery and a glomus cell mass of CB. Under long-termed mechanical stress, a muscular artery seems to lose smooth muscles with increased sympathetic nerve fibers, to compensate for the lack of muscle function. Taken together with fetal morphology (our recent report), some or most of the CBs might not be an arteriovenous shunt but a result of stress-induced acquired transformation of pericytes. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1826-1837, 2017. © 2017 Wiley Periodicals, Inc.

Analysis of Sacrococcygeal Morphology in Koreans Using Computed Tomography

Background

The sacrococcygeal morphology of Arabs and Europeans has been studied using computed tomography (CT) or magnetic resonance imaging to determine the cause of coccydynia. Studies have suggested differences in sacrococcygeal morphology among ethnic groups. However, there are no data on the sacrococcygeal anatomy of Koreans.

Methods

We conducted a retrospective analysis of 606 pelvic CT scans that were taken at Cheju Halla General Hospital between 2008 and 2014. Fractures of the sacrum or coccyx were excluded. Differences in the sacrococcygeal morphology among age groups stratified by decade of life and between genders were analyzed using sagittal plane pelvic CT scans. The morphological parameters studied were the sacral and coccygeal curved indexes, sacrococcygeal angle, intercoccygeal angle, coccygeal type, coccygeal segmental number, and sacrococcygeal fusion.

Results

The average sacral and coccygeal curved indexes were 6.15 and 7.41, respectively. The average sacrococcygeal and intercoccygeal angles were 110° and 49°, respectively. Type II coccyx was most common, and the rate of sacrococcygeal fusion was 34%. There was a moderate positive correlation between age and the sacral curved index (r = 0.493, p = 0.000) and a weak negative correlation between age and the coccyx curved index (r = −0.257, p = 0.000). There was a weak negative correlation between age and the intercoccygeal angle (r = −0.187, p = 0.000). The average intercoccygeal angle in males and females was 53.9° and 44.7°, respectively.

Conclusions

The sacrum tended to be more curved and the coccyx straighter with age. The coccyx was straighter in females than males. Knowledge of the sacrococcygeal anatomy of Koreans will promote better understanding of anatomical differences among ethnicities and future studies on coccydynia.

Computed tomography-based morphologic and morphometric features of the coccyx among Arab adults

STUDY DESIGN

Cross-sectional, retrospective.

OBJECTIVE

To identify morphological and morphometric features of the coccyx among adult Arabs.

SUMMARY OF BACKGROUND DATA

Different sacrococcygeal morphologic features were found to be associated with coccydynia.

METHODS

Review of 202 computed tomographic scans of adult Arab subjects was done (mean age: 47.98 ± 16.46 yr). Sacrococcygeal morphological features including number of coccygeal segments, type of coccyx, joint fusion, joint subluxation, coccygeal spicule, coccygeal sacralization, ventral angulation of the terminal sacral segment (S5), and lateral deviation of coccygeal tip were recorded. Moreover, morphometric measurements including lengths and angles of the sacrococcygeal region were measured. Analysis of data was carried out using P value of less than 0.05 as the cutoff level of significance.

RESULTS

Three coccygeal segments were present in 138 (68.3%) of individuals. The majority of the subjects had coccyx type I (96; 47.5%), II (70; 34.7%), or III (31; 15.3%); type I being more common among males (P = 0.004). Bony spicule was present in 109 (54.0%) individuals. Joint fusion, joint subluxation, coccygeal sacralization, ventral angulation of S5, and lateral deviation of coccygeal tip were present in 38.6%, 31.7%, 34.2%, 38.1%, and 38.6% of the subjects, respectively. Joint subluxation and ventral angulation of S5 were more significantly present among females (P = 0.015, P = 0.014, respectively). The mean straight and curved lengths of the coccyx were 3.3 ± 0.7 cm and 3.7 ± 0.8 cm, respectively. The sacrococcygeal structures were longer in males than in females. The mean sacrococcygeal joint angle was 149.2°± 28.1°. Based on the morphometric measurements, the coccyx was more ventrally angulated among females.

CONCLUSION

The coccygeal morphology and morphometry of Arab adults share some similarities and differences with individuals of other ethnic backgrounds. Future studies should investigate the relation between these anatomic features with coccydynia among this population.

LEVEL OF EVIDENCE

3.