Canal Width Research Articles

Anatomical Features of the Proximal Femur in the Turkish Population

Different populations have different genetic traits, and this causes various anatomical features to emerge. Orthopedic implants used in Turkey are generally of Western origin, and these implants are designed based on the anatomical features of Western populations. This study aimed to evaluate the compatibility of existing implants for the Turkish population by revealing the anatomical features of the proximal femurs of individuals from the Turkish population while also constituting a helpful source of data on newly developed implants. A total of 1920 proximal femurs of 960 patients were evaluated via images obtained by Computer Tomography. Twenty patients (10 females and 10 males) for each age within the age range of 18-65 years were included. Femoral head diameter, femoral neck width, femoral neck length, medullary canal width, and collodiaphyseal angle were measured. The right and left femoral head diameter was 46.46±3.84 mm, 46.50 ±3.85 mm respectively. The right and left femoral neck width was 30.63±3.4 mm, 30.85±3.29 mm respectively. The neck length was 94.62±8.33 mm for the right proximal femur, it was 94.75±8.19 mm for the left. The width of the medullary canal was 15.46±2.25 mm for the right proximal femur and 15.53±2.20 mm for the left. The right and left hips, the collodiaphyseal angles were 133.06±2.39° and 133.13±2.36°. Anatomical features of the proximal femur vary according to age, sex, and race. This study may be used as an important resource for the evaluation of patients’ compatibility with existing implants and for the design of new implants.

A novel approach in the prevention of mastitis: electrical teat dipping.

Teat dipping is widely used in dairy cattle, especially to protect against contagious mastitis. Here we determine the effect of the device called 'Electrical Teat Dipping' (ETD), which was developed by combining teat dipping application and electrical field stimulation technique on teats. For this purpose, the front teats of 100 Holstein breed milking cows were evaluated in two groups, with ETD being applied once to the left front teat of these cows, and conventional teat dipping (CTD) being applied once to the right front teat, both after milking. Ultrasonographic measurements of the teats were made before milking and after teat dipping. We found that the width of the teat canal (1.88 ± 0.07 mm) in the teat using ETD was narrower after the application compared to those with CTD (2.28 ± 0.05 mm). Based on our findings, we conclude that the effects of ETD on the teat are very positive and can potentially be used as a new approach in the preventative control of mastitis in cows.

A Comparison of Canal Width Changes in Simulated Curved Canals prepared with Profile and Protaper Rotary Systems

With advancement in the endodontic technology there is a quest to introduce root canal instruments showing superior performance by removing minimum amount of sound root dentine and retaining the original shape of the root canal. Objective: To compare the changes in the width of simulated curved canals prepared with ProFile and ProTaper rotary system. Methods: This in-vitro, Quasi Experimental study was carried out in the Dental section of The Aga Khan University Hospital. Pre and post instrumentation photographs (images) of sixty resin blocks prepared with ProFile and ProTaper rotary instruments respectively (with 1:10 magnification) were superimposed using software Adobe Photoshop 6.0. Measurements were done on print out of composite images. Measurements of change in width (resin removed) were recorded along the length of canal at 12 points. Results: Two rotary system showed statistically significant difference in simulated curved canals width after preparation. ProTaper rotary instruments showed more resin removal at the inner walls of the canal at 1, 8-12mm from the apex and more resin removal at outer wall of canal at 9-12 mm from apex. Conclusions: ProFile and ProTaper rotary files showed statistically significant difference in canal width after instrumentation. ProTaper rotary files showed more resin removal in canals towards the inner wall and coronal part of the outer wall.

Parallel evolution of semicircular canal form and sensitivity in subterranean mammals.

The vertebrate vestibular system is crucial for balance and navigation, and the evolution of its form and function in relation to species' lifestyle and mode of locomotion has been the focus of considerable recent study. Most research, however, has concentrated on aboveground mammals, with much less published on subterranean fauna. Here, we explored variation in anatomy and sensitivity of the semicircular canals among 91 mammal species, including both subterranean and non-subterranean representatives. Quantitative phylogenetically informed analyses showed significant widening of the canals relative to radius of curvature in subterranean species. A relative canal width above 0.166 indicates with 95% certainty that a species is subterranean. Fluid-structure interaction modelling predicted that canal widening leads to a substantial increase in canal sensitivity; a reasonably good estimation of the absolute sensitivity is possible based on the absolute internal canal width alone. In addition, phylogenetic comparative modelling and functional landscape exploration revealed repeated independent evolution of increased relative canal width and anterior canal sensitivity associated with the transition to a subterranean lifestyle, providing evidence of parallel adaptation. Our results suggest that living in dark, subterranean tunnels requires good balance and/or navigation skills which may be facilitated by more sensitive semicircular canals.

A practical method for rehabilitation of stormwater collecting system by node flooding detection and regional hydraulic redesign: a case study of eastern Tehran metropolis.

This study investigates the effect of structural modification actions on the existing stormwater collecting system in Eastern Tehran to increase the hydraulic capacity and create suitable conditions for the passage of runoff in the critical points of the canal. First, the hydraulic conditions within the stormwater collecting system were simulated using the Stormwater Management Model (SWMM) model before/after the modification to investigate the rehabilitation results. Three critical locations along the main canal were recognized as the most vulnerable points. Then, based on field visits and brainstorming sessions, rehabilitation methods were presented, and three practical solutions, including canal deepening, canal widening, and their combination, were investigated for each. Then, local investigating based on the rehabilitation alternatives for each critical location was conducted using the HEC-RAS. Finally, the SWMM model was used again to evaluate the overall operational performance of the stormwater collecting system after the rehabilitation. The results revealed that it is necessary to implement two alternatives of deepening and widening to provide adequate transmission runoff capacity during rainfalls with various return periods. More specifically, the localized redesign of the eastern flood diversion canal had an acceptable improvement in reducing flooding problems so that for floods with a return period of 10 years, the number of node flooding dropped from 4 to 0, inundated areas from 17% to 0, and the overflow volume from (10-45) to 0. Moreover, the proposed local rehabilitation reduced the overflow volume from (30-65), (43-74), and (70-92) in the status quo to (4-12), (11-27), and (24-36) for rainfall with 25, 50, and 100-year return periods.

Shaping ability of new reciprocating or rotary instruments with two cross-sectional designs: An ex vivo study.

This study compared the shaping ability of four new reciprocating and rotary nickel-titanium instruments, with triangular or S-shaped cross-section, in the mesial canals of mandibular molars using micro-computed tomographic (micro-CT) evaluation. Twenty-four extracted mandibular molars with Vertucci's class IV configuration in the mesial root were selected for this study. The teeth were matched in fours according to anatomic similarities as revealed by micro-CT and then distributed into four groups of 12 mesial canals each according to the instrumentation technique: Reciproc Blue, R-motion, VDW.Rotate and RaCe EVO. The final apical size of instrumentation was 30/0.04 for three systems and 25/08 for the Reciproc Blue instrument. Micro-CT scans were taken before and after preparation to evaluate the canal volume, area and unprepared surface areas, as well as the centring ability, and the canal: root width ratio. Preparation with all systems significantly increased the volume and area of the canals (p < .05). There were no significant differences between groups regarding the amount of unprepared areas in both the apical and full canal lengths (p > .05). Variation in the centre of gravity showed no significant difference between groups either (p > .05). The canal: root width ratio at levels 0 and 4 mm apically to the coronal canal opening was significantly increased by all systems (p < .01), with no significant differences between groups (p > .05). The canal width never exceeded 40% of the root width. Reciprocating or rotary instruments, with a triangular or an S-shaped cross-section, performed equally in shaping Vertucci's class IV mesial canals of mandibular molars.

The conundrum of olecranon aperture and its relation to the distal end of the humerus in a modern Indian population: An anatomical and surgical perspective

We aimed to clarify the morphology of the olecranon aperture (OA) of the humerus with its relationship to the distal end of the humerus (epicondylar width) and the width of the medullary canal. In total, 156 dry adult humeri were examined for the presence of OA. When present, we reported their shape, measured transverse (TD) and vertical diameter (VD), the distance from its medial border to the tip of medial epicondyle (D1), lateral border to the tip of lateral epicondyle (D2) and lower border to the tip of trochlea (D3). The epicondylar width (EW) and the width of the medullary canal were also measured in all the humeri. OA was reported in 32 humeri (20.6%) with left side predominance, translucent septum in 35.8%, and opaque septum in 43.6%. The most typical shape noted was oval. On right side, mean VD and TD was 4.30±0.54mm and 5.85±0.45mm, respectively, whereas on left, these value were 4.21±0.56mm and 5.64±0.43mm, respectively. The mean of D1, D2 and D3 was 25.86±0.43mm, 26.50±0.28mm and 15.07±0.53mm on right and 24.80±0.41mm, 26.84±0.21mm and 15.81±0.31mm on left with significant difference (P<0.05). The medullary canal was significantly smaller in humeri with OA. Topographic location of OA may have possible role in determining safe zone for retrograde nailing in supracondylar humeral fractures. Since OA has a direct relation to the size of the intramedullary canal, it is crucial during preoperative planning and choosing an adequate surgical approach involving lower segment of humerus.

The position and morphology characteristics of multiple impacted anterior teeth in the unilateral maxillary area: A retrospective study based on cone-beam computed tomography

This study investigated the position and morphologic characteristics of multiple impacted anterior teeth in the unilateral maxillary area. Cone-beam computed tomography images of 21 patients (11 males and 10 females; median age 9.42 years [9.08-11.29]) with multiple teeth impacted were collected and imported into Dolphin Imaging software (Dolphin Imaging and Management Solutions, Chatsworth, Calif). The vertical height, crown orientation, twist direction, and root curvature of each impacted tooth were described. The crown length, root length, and root canal width of impacted and homonym teeth were measured. The positions of the impacted lateral incisors are lower than that of the other 2 anterior teeth. Most crowns of impacted central incisors are positioned distally, labial surfaces in mesial torsion, with most roots, bent toward the distal and labial. Crowns of impacted lateral incisors are positioned mesiolabially, with labial surfaces mostly in distal torsion, and most roots bent toward the mesial and labial. Crowns of impacted canines are mostly positioned mesiolabially, with labial surfaces in mesial torsion. The crowns and roots of the impacted central and lateral incisors were shorter than those of the homonym (P<0.05); however, the difference in crown length is clinically negligible, and there was no difference in root canal widths. There was no difference in the comparison of parameters for the canine group. There are certain rules in the vertical height, crown orientation, twist direction, and root curvature of multiple impacted anterior teeth in the unilateral maxillary area. Root development of impacted central and lateral incisors was restricted.

Age-Associated Changes in Proximal Femur Morphology Affect Femoral Component Sizing in Cementless Hip Arthroplasty

In cementless hip arthroplasty, the femoral component should obtain firm fixation within the endosteal bone and achieve adequate reconstruction of hip joint biomechanics simultaneously. Previous anatomical studies described age-related changes of the proximal femoral canal, such as canal widening, which theoretically necessitates the use of larger stem sizes in elderly patients. This study examines a potential association between patients' age at surgery and the implant size of a cementless femoral component. A total of 13,423 primary hip arthroplasties with a single cementless stem registered in the Dutch Arthroplasty Register (LROI) were included. Patient characteristics (ie patients' age, sex, height and weight at time of surgery) and femoral component size were derived. A one-way ANCOVA was used to compare the mean stem size between age groups, and multivariable linear regression analysis was used in order to investigate to which extent ageing impacted stem size. Each subsequent age- group (ten-year intervals) had a significantly larger mean stem size than the prior age- group. Multivariable linear regression analysis revealed that age is positively correlated with stem size and that this correlation is more prominent in females than in males (beta = .046, P < .001 and beta = .028, P < .001 respectively). Implant size is positively correlated with age, in particular in females and independently from investigated anthropometric characteristics. The present study endorses that the femoral canal morphology is related to patients' characteristics such as age and sex. The morphology will subsequently influence implant sizing and therefore may have biomechanical and clinical implications.

Do the Age of Implantation, the Widths of Internal Acoustic Canal and Bony Cochlear Nerve Canal Affect the Auditory Performance of Primary School Children with Bilateral Cochlear Implants?

Objective:To reveal the correlation between implantation age, the internal acoustic canal (IAC) width, bony cochlear nerve canal (BCNC) width, and auditory performance in primary school children with bilateral cochlear implantation (CI).Methods:Preoperative IAC and BCNC widths of 57 pre-lingually deaf children aged 7–11 years who had previously undergone bilateral CI in our institution were reviewed and cut-off values were calculated. Twenty-four patients who had additional problems and could not attend school and those who refused to participate in the study were excluded. The remaining 33 were invited to the hospital, and their speech perception tests, and language development scores were analyzed (16 of 33 patients had been operated on before the age of 24 months).Results:The cut-off values calculated from the 114 ears of 57 patients were 3.86 mm for IAC width and 1.56 mm for BCNC width. The auditory performances of the 33 patients after CI were not significantly different in the narrow and normal width groups. However, speech perception test results, and language development scores of patients implanted before the age of 24 months were significantly higher.Conclusion:There are some studies showing that children with bilateral sensorineural hearing loss have narrower IAC and BCNC widths. However, we concluded that the widths of the IAC and the bone cochlear nerve canal did not affect auditory performance. We found that implantation age is the single most important determinant of speech-language development after CI.

The burning maze: The potential value of the human bony labyrinth in estimating sex of calcined remains.

Estimating sex from burnt human remains is a challenging task in bioanthropology, mainly due to their high level of alteration and fragmentation. Protected within the petrous part of the temporal bone, the bony labyrinth may be particularly valuable for assessing the sex of burnt remains. This prospective study aims at testing predictive models, already found reliable on unburnt bony labyrinths, to burnt specimens. Six discriminant functions were applied on six bony labyrinths of donated adult cadavers of known sex, before and after outdoor burning experiments. Comparisons between unburnt and burnt measurements were executed using Mann-Whitney U tests while shape and size differences induced by fire exposure were examined through a geometric morphometrics (GM) analysis. Predicted sex on unburnt bony labyrinths was consistent with known sex in five cases while a systematic misclassification for males was highlighted on burnt specimens. Higher values of shrinkage were found in males for two measurements included in the equations. GM analysis revealed significant differences in centroid size among males after calcination. Visualization of mean consensus of both female and male bony labyrinths evidenced a reduction in cochlear size and variations in the width and length of semicircular canals of burnt specimens. This exploratory study seems to confirm that designing sex estimation standards specifically for burnt bony labyrinth may be advisable. Understanding how the burning process could impact its morphology is highly recommended through further experiments on larger samples and in controlled environments.

Root canal width as a mandibular maturity marker at the 18-year threshold in the Maltese population.

The determination of age of majority (the 18-year-old threshold) using the popular Demirjian tooth staging method is unreliable, so other maturity markers are required. This study examines whether the ratio of the root canal widths (RCW) of the mandibular first, second and third molars is a useful indicator of age. Nine hundred eighteen dental panoramic radiographs (DPT) were examined and the ratio of the mid-points of the distal roots of the left mandibular first, second and third molars assessed according to the RCW stages as described by Roberts (J Forensic Sci 62:351-354, 2017). Individuals who had reached stages RCW-A and RCW-B were represented in a wide range of ages spanning the 18-year-old threshold. Individuals who had reached Stage RCW-C were all above the 18-year-old threshold. It was not possible to analyse a large number of DPTs for various reasons. Individuals categorised as stage RCW-C may be deemed to have reached the 18-year-old threshold. These results are consistent with other published studies. Variation in root morphology and in the rate of development of the third molar limits the applicability of this method. RCW staging is an accurate method of determining the 18-year-old threshold. Its limited applicability requires the use of substitute markers in a large number of cases.

In Vitro Evaluation of Bond Strength to Dentin of Two Post Systems: Computer-aided Design and Computer-aided Manufacturing Fiber Posts vs Splendor Single Adjustable Post

To assess dentin-post bond strength and mode of failure through tensile strength testing of two endodontic post systems: CAD/CAM custom-milled fiber posts vs Splendor SAP. Thirty extracted single-rooted mandibular premolars were sectioned 2 mm coronal to the cementoenamel junction. Root length was standardized at 15 mm, and the root canals were instrumented with #20 K-files followed by 30/0.03 and 30/0.05 ProDesign Logic rotary files, under irrigation with 2.5% NaOCl, and then submitted to final irrigation with 17% EDTA. Canals were filled with gutta-percha and AH PLUS sealer. After 24 hours, the teeth were prepared for post placement to a depth of 10 mm and randomly allocated into two experimental groups (n = 15): CAD/CAM (CC) and Splendor SAP (SS). All posts were cemented with RelyX U200 dual-cure self-adhesive resin cement. The roots were embedded in acrylic resin, and the specimens were stored for 7 days in moist heat (37°C). Tensile strength testing until failure was then performed in a universal testing machine using a crosshead speed of 0.5 mm/minute. The final failure load was tabulated for statistical analysis, and the G test was used to compare the failure modes observed under light microscopy (5× magnification). There was no significant difference between groups regarding tensile bond strength to root dentin (p = 0.325). Conversely, failure mode differed significantly between groups (p = 0.037). The tensile bond strength observed for the CAD/CAM and Splendor SAP post systems was similar. Adhesive failure was predominant in both groups; however, the CAD/CAM custom-milled fiber posts failed predominantly at the dentin-resin cement interface, whereas Splendor SAP posts failed mostly at the post-resin cement interface. A strong post-dentin bond is a key to the success of dental restorations and prosthetic rehabilitation. In teeth with severe coronal decay and wide canals, both of the tested systems would be able to achieve good cervical fit.

Surgical Planning and Simulation of Endonasal Endoscopic Surgery for Pituitary Adenoma With Cavernous Sinus Invasion.

Transsphenoidal endoscopic endonasal surgery (EES) provides effective treatment for patients with lesions of the sella turcica. The endoscopic technique requires different instrumentation, which depends on the gross anatomy of the nasal cavity. The treatment of lateral lesions is more challenging in EES. To evaluate the effect of preoperative simulation using multiple anatomic landmarks. Pre- and postoperative tumor volumes were analyzed in 33 patients with nonfunctioning pituitary adenomas who underwent EES (Knosp grades 3 and 4). The surgical working angle and space were three-dimensionally simulated at the plane of the anterior/posterior surgical field (tuberculum sellae/posterior clinoid process) using multiple anatomic landmarks of high-resolution computed tomography scans, such as nasal piriform aperture (proximal surgical corridor), and the width of bilateral vidian canals or lamina perpendicularis of palatine bone (distal surgical corridor). Receiver operating characteristic curves for the removed tumor volume were used to determine the cutoff value for the simulated working angle and space. Simulated working space at the plane of tuberculum sellae using piriform aperture and lamina perpendicularis of palatine bone was associated with the removed tumor volume in the cavernous sinus. Patients with a larger working space (≥42.7 mm) significantly showed a higher removed tumor volume ( P = .023). There was no relationship between other parameters and the removed tumor volume. A new method to predict the surgical field for cavernous sinus lesions around sella turcica was successfully established. Further studies are needed to define and expand applications of this simulation method.

CLINICAL-MORPHOMETRIC RATIO OF DEGENERATIVE-DYSTROPHIC PROCESSES OF THE CERVICAL SPINE IN HUMANS AND ANIMALS IN SPINAL CHANNEL STENOSIS

Relevance. Spinal stenosis is a common manifestation of degenerative-dystrophic lesions of the cervical spine (CS). In most cases it occurs with the development of neurological complications in the form of secondary spondylogenic myelopathy, radicular dysfunction, pain. Isolated studies indicate that this type of damage occurs in some animals.&#x0D; Objective: a comparative analysis of clinical, radiological and morphometric data on degenerative-dystrophic lesions in human and domestic animals on the background of degenerative changes in bone structures that provoke stenosis of the spinal canal with the development of spondylogenic myelopathy.&#x0D; Material and methods. The retrospective analysis included 65 patients (25 men, 40 women) with neurological symptoms who underwent computed tomography during 2018-2021. Prospectively, a study was performed with the participation of 75 domestic animals with similar symptoms (19 dogs of large breeds weighing more 20 kg, 42 dogs of small and medium breeds weighing less 20 kg, and 14 cats.&#x0D; Results. There was a close correlation of symptoms in humans and large dogs in the presence and degree of narrowing of the canal: in cases of stenosis of the ventricles in humans (75.3%), large breeds of dogs (78.9%), patients had similar neurological symptoms. The maximum decrease in the sagittal diameter of the spinal canal was found more at the level of the C6 vertebral body in both humans and animals, weighing more than 20 kg. The mass share of stenotic changes was mainly registered in men (84.0% vs. 70.0% in women). In addition, according to the Pavlov-Torg morphometric index, the width of the spinal canal in men was smaller than in women. Stenosis of the spinal canal was mainly registered in large breeds of dogs (78.9%), which almost completely coincided with the morphometry in humans (75.4%).&#x0D; Conclusions. The data of our research indicate the possibility of using large breeds of dogs in predicting the course of degenerative-dystrophic changes in humans, because physiological and pathophysiological processes in dogs are on average 7 times faster than in humans. The severity of the process, the clinic and morphometric data of CS animals depend on the species, breed, weight, age, and common factors in the development of degenerative-dystrophic changes in humans and some groups of animals may be aging in general and the spine in particular.

Evaluation of thoracic vertebrae in healthy White New Zealand rabbit (Oryctolagus Cuniculus): Computed tomographic and morphometric study.

BackgroundComputed tomography currently has a prominent role in diagnosis and evaluation of vertebral column. On the other hand, a thorough knowledge about vertebral column property in normal state is prerequisite an accurate diagnosis of different abnormalities in this region.ObjectiveThe purpose of this study was to present a complete and exact descriptive and morphometric evaluation of thoracic vertebrae in rabbits with computed tomography. In images which were constructed by CT, several structures and different parts of the thoracic vertebrae have been named.MethodsTen healthy, mature, White New Zealand rabbits were evaluated. The morphologic and morphometric parameters of the thoracic vertebrae were studied. In this study, several parameters of thoracic vertebrae, such as vertebral body height, spinous process height, transverse process length, transverse process width, etc., were measured by computed tomography.ResultsSome parameters, such as spinal canal height, spinal canal width, pedicle length, pedicle width, end plate width, and endplate height, had no significant difference through thoracic vertebrae but other parameters, such as vertebral body height, transverse process length, transverse process width, spinous process angle, transverse process angle, and vertebral body length, had a significant difference.ConclusionsIn this study, a comprehensive anatomic atlas of CT anatomy of the thoracic vertebrae was produced for use by veterinary radiologists, clinicians, and surgeons. Finally, we must mention these two important points: (1) Many of the differences observed between rabbits and humans are based on the way the trunks of these two creatures are located on the ground and the differences in the way their bodies move. (2) In studies that are done by modelling humans on animals, it should be noted that the terms used in animal anatomy are different and the names are used using the principles of veterinary anatomy.

Tsunami-Induced Bores Propagating over a Canal, Part II: Numerical Experiments Using the Standard k-ε Turbulence Model

This companion paper presents the results of a series of numerical experiments examining the effects of a mitigation canal on the hydrodynamics of a tsunami-like turbulent bore proceeding over a horizontal bed. The hydraulic bores were generated by a dam-break setup which employed impoundment depths of do = 0.20 m, 0.30 m, and 0.40 m. The bore propagated downstream of the impoundments in the flume and interacted with a canal with varying geometry located downstream. The bore then left the flume through a drain located further downstream of the canal. In this study, the effect of the canal depth on the specific momentum and specific energy of hydraulic bores passing over a rectangular canal is numerically studied. The canal width was kept constant, at w = 0.6 m, while the canal depths were varied as follows: d = 0.05 m, 0.10 m, and 0.15 m. The time history of mean flow energy during the bore’s passing over the mitigation canal indicates that the jet stream of the maximum mean flow energy is controlled by the canal depth. The time required to dissipate the jet stream of the maximum vorticity, the turbulent kinetic energy, and the energy dissipation rate all increased as the canal depth decreased. The effect of canal orientation on the bore hydrodynamics was also numerically investigated, and it was found that the impulsive momentum and specific energy reached the highest values for canal orientations of 45 and 60 degrees. For the same canal depth, the highest peak specific momentum occurred with the highest degree of canal orientation (θ = 60°).

An Anatomic Study Examining Lumbar Pars Interarticularis Distance and Spinal Canal Width in Relation to Lumbar Decompressive Surgery.

Lumbar laminectomy is a surgical procedure allowing for decompression of neural structures. A wide laminectomy to adequately decompress neural elements without compromising the structural integrity of the spinal column is ideal. Pars interarticularis fractures with spinal instability after isolated laminectomy from overresection of the posterior elements have been reported. There are limited anatomical studies in the spine literature that measure the pars interarticularis distance (PID) and spinal canal width (SCW) in the lumbar spine. The purpose of this study was to assess the differences in PID and SCW at each level of the lumbar spine and to determine their effects on the extent of laminectomy at each lumbar level. We performed an anatomic study measuring PID and SCW in the lumbar spine from 93 skeletally matured osseous specimens. Groups were compared using an independent sample t test, 1-way analysis of variance, and Wilcoxon test, and significance was set at P < 0.05. Our study suggests that the distance between PID and SCW increases from L1 to L5 in African American and Caucasian women and men. However, the respective increase in SCW at each lumbar level is less than the respective increase in PID at the same levels. This trend suggests that there is a wider window available for decompression without compromising spinal stability in the lower lumbar spine compared with the upper lumbar spine. Our findings suggest that the upper lumbar spine has a narrower window for decompression; therefore, care should be taken to preserve as much of the pars at L1-L3. Understanding the variations in PID and SCW in the lumbar spine will help surgeons perform adequate decompression of a stenotic canal while avoiding postoperative spinal instability. Awareness of PID to SCW ratio may help spine surgeons avoid iatrogenic instability, postoperative intractable back pain, spondylolisthesis, or complications involving alterations of the lumbar spine biomechanics.

Value of Preoperative Imaging Results in Predicting Cochlear Nerve Function in Children Diagnosed With Cochlear Nerve Aplasia Based on Imaging Results.

This study aimed to assess the function of the cochlear nerve using electrically evoked compound action potentials (ECAPs) for children with cochlear implants who were diagnosed with cochlear nerve aplasia and to analyze the correlation between preimplantation imaging results and ECAP responses. Thirty-five children diagnosed with cochlear nerve aplasia based on magnetic resonance imaging (MRI) were included. Preimplantation MRI and high-resolution computed tomography (HRCT) images were reconstructed, and the width of the bone cochlear nerve canal (BCNC), the diameter of the vestibulocochlear nerve (VCN), and the diameter of the facial nerve (FN) were measured. ECAP input/output (I/O) functions were measured at three electrode locations along the electrode array for each participant. The relationship between ECAP responses (including ECAP threshold, ECAP maximum amplitude, and slope of ECAP I/O function) and sizes of the BCNC and VCN was analyzed using Pearson's correlation coefficients. Our analysis revealed that ECAP responses varied greatly among individual participants. Overall, ECAP thresholds gradually increased, while maximum amplitudes and ECAP I/O function slopes gradually decreased, as the electrode location moved from the basal to the apical direction in the cochlea. ECAP responses exhibited no significant correlations with BCNC width or VCN diameter. The ratio of the VCN to FN diameters was significantly correlated with the slope of the ECAP I/O function and the maximum amplitude. BCNC width could not predict the function of the cochlear nerve. Compared with the absolute size of the VCN, the size of the VCN relative to the FN may represent an indicator for predicting the functional status of the cochlear nerve in children diagnosed with cochlear nerve aplasia based on imaging results.

Thoracolumbar stenosis and neurologic symptoms: Quantitative MRI in achondroplasia.

Background and PurposeWhole‐spine magnetic resonance imaging (MRI) studies, to identify structural abnormalities associated with the development of symptomatic spinal stenosis in achondroplasia.MethodsForty‐two subjects with achondroplasia were grouped into four age‐related categories. Congenital spinal deformities (vertebral body and disc height, interpedicular distance), acquired spinal degenerative changes, thoracic kyphotic (TK) angle, thoracolumbar kyphotic (TLK) angle, spinal canal widths were evaluated by MRI.ResultsPatients in the first three groups were asymptomatic and younger (group 1: 4.4 ± 0.78 years; group 2: 8.18 ± 0.60 years; group 3: 10.95 ± 0.93 years) than the symptomatic group (group 4: 23 ± 1.30 years). Patients showed height of vertebral bodies, whole canal width, and average lumbar interpedicular distance reduced. Discs degeneration was more pronounced in the lumbar region and in symptomatic adult patients. TK and TLK angles showed a positive correlation with age (p < .05, r = .42; p < .05, r = .41), whereas thoracic and thoracolumbar canal width had a negative correlation (p < .05, r = −.69; p < .05, r = −.58). A negative correlation between lumbar discs degeneration and canal width was found only at L1‐L3 level (p < .05, r = −.35). At L1‐L3, the canal width cutoff value of .59 allowed the differentiation between asymptomatic and symptomatic patients (area under the curve of .966, p < .0001).ConclusionIn achondroplasia, the spinal canal narrowing, due to accelerated degenerative changes, is a predisposing factor of symptomatic lumbar spinal stenosis. Lumbar canal MRI is a helpful tool to detect the risk of the development of neurological symptoms; in adult patients, a stenosis higher than 60% of upper lumbar canal could be a critical value for the onset of neurological symptoms.