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To evaluate the stability and function of the C1-C2 joint after ectopic functional reconstruction (EFR) of the C1 transverse ligament. Eight human cadaveric cervical spines (C0-C4) were subjected to in vitro biomechanical test with moment control. Spine specimens were tested under the following conditions: 1) left intact; 2) destabilized by severing the transverse ligament of atlas; 3) after EFR of the transverse ligament. Range of motion was measured in flexion, extension, lateral bending, and axial rotation. Destabilization significantly increased range of motion in all directions compared with the intact status (P < 0.001). However, after EFR of the transverse ligament, range of motion in all directions was restored to the intact state. Meanwhile, coupling motions were reproduced in the axial rotation. EFR of the transverse ligament virtually recovers all the physiological functions of the native transverse ligament and might be a promising alternative for the treatment of anterior atlantoaxial dislocation. Further studies are warranted before clinical application of EFR of the transverse ligament. [ABSTRACT FROM AUTHOR]

Some atlantoaxial rotatory fixations (AARFs) cannot be classified according to the Fielding and Hawkins classification. This study aimed to introduce a new subtype of AARF (type IIIa AARF) with a C1 anterior displacement >5 mm, but with one lateral mass being displaced anteriorly and another posteriorly. Data from 10 cases of AARF with anterior C1 displacement of >5 mm were retrospectively reviewed. The exclusion criteria were as follows: 1) type I, II, or IV AARF according to the Fielding and Hawkins classification; 2) cases caused by trauma, tumor, or infection; 3) AARF with os odontoideum or odontoid fracture; and 4）age ≥18 years. Imaging features were analyzed. The atlanto-dental interval was measured to evaluate C1 anterior displacement. Three cases that did not match type III AARF were classified under type IIIa AARF. They had the following common imaging features: 1) atlanto-dental interval of >5 mm, being similar to type III AARF; 2) one lateral mass of C1 displaced anteriorly and the other posteriorly (the most important feature distinguishing the type from type III AARF in which both C1 lateral masses displaced anteriorly); and 3) C1-C2 separation angle (mean 44.2 ± 2.9°) being larger than that in type III AARF. AARF with anterior C1 displacement of >5 mm, but with one lateral mass displaced anteriorly and the other posteriorly, was defined as type IIIa AARF. It should not be confused with type III AARF because these 2 types differ in biomechanics and imaging parameters. [ABSTRACT FROM AUTHOR]

Purpose Atlantodens osteoarthritis and atlantoaxial osteoarthritis cause neck pain and suboccipital headaches. Currently, knowledge on the risk factors for atlantoaxial osteoarthritis is lacking. This study aimed to investigate the factors related to the increased risk of atlantoaxial osteoarthritis. Methods We analyzed computed tomography (CT) images of the upper cervical spine of 1266 adult trauma patients for whom upper cervical spine CT was performed at our hospital between 2014 and 2019. The degree of atlantoaxial osteoarthritis was quantified as none-to-mild (not having osteoarthritis) or moderate-to-severe (having osteoarthritis). Risk factors associated with atlantoaxial osteoarthritis were identified using univariate and multivariable logistic regression analyses. Results The study group included 69.4% men, and the overall average age of the study population was 54.9 ± 20.4 years. The following factors were independently and significantly associated with atlantoaxial osteoarthritis in the multivariable logistic regression analysis: age in the sixth decade or older (odds ratio [OR], 20.5; 95% confidence interval [CI], 6.2‒67.2, p < 0.001), having calcific synovitis (OR, 4.9; 95% CI, 2.4‒9.9, p < 0.001), women sex (OR, 3.3; 95% CI, 1.9‒5.7, p = 0.002), and not having atlantodens osteoarthritis (OR, 2.1; 95% CI, 1.2‒3.8, p = 0.014). Conclusion In the multivariable logistic regression analysis, age in the sixth decade or older, calcification of the transverse ligament, being women, and not having atlantodens osteoarthritis were found to be significantly associated with atlantoaxial osteoarthritis. Delayed diagnosis and treatment can be avoided by focusing on these risk factors. [ABSTRACT FROM AUTHOR]

Purpose: Ponticulus posticus (PP) is a variation of the bone bridge that appears in the first cervical vertebra and through which the vertebral artery passes. Odontoid fractures are common spinal bone fractures in older people. This study aims to investigate the effect of neck movements on the odontoid and transverse atlantal ligament (TAL) of people with PP variation from a biomechanical view.Method: C1, C2, and C3 vertebrae of the occipital bone were analyzed using the finite element method (FEM). In this study, solid models were created with the help of normal (N), incomplete (IC), and asymmetric complete (AC) PP tomography images. The necessary elements for the models were assigned, and the material properties were defined for the elements. As boundary conditions, models were fixed from the C3 vertebra, and 74 N loading was applied from the occipital bone. Stress and deformation values in the odontoid and transverse atlantal ligament were obtained by applying 1.8 Nm moment in flexion, extension, bending, and axial rotation directions.Results: The stress and deformation values of all three models in odontoid and TAL were obtained, and numerical results were evaluated. In all models, stress and deformation values were obtained in decreasing order in rotation, bending, extension, and flexion movements. The highest stress and strain values were obtained in AC and the lowest values were obtained in N. In all movements of the three models, the stress and deformation values obtained in the TAL were lower than in the odontoid.Conclusion: The greatest stresses and deformations obtained in spines (AC) with PP were found in the odontoid. This may help explain the pathogenesis of odontoid fractures in older people. First, this study explains the mechanism of the formation of neck trauma in people with PP and the need for a more careful evaluation of the direction of impact. Secondly, the study reveals that the rotational motion of the neck independent of PP has more negative effects on the odontoid. [ABSTRACT FROM AUTHOR]

Background Traumatic posterior atlantoaxial dislocation (PAAD) without fracture of the odontoid process is a rare injury. Closed reduction by skull traction under C‐arm fluoroscopic guidance and open reduction have been reported previously for the treatment of PAAD. Objective To report a rare case of PAAD without fracture treated by closed manual reduction and posterior fixation. To provide a new method—atlantoaxial dynamic test—for confirming the integrity of the transverse ligament after reduction and evaluate the ideal treatment strategy for traumatic PAAD without fracture of the odontoid process or rupture of the transverse ligament. Method A 54‐year‐old woman was riding in the passenger seat when her vehicle was rear‐ended by a car. X‐ray and computed tomography (CT) scans were used to diagnose PAAD without a related fracture. Closed manual reduction under C‐arm fluoroscopy was performed after applying general anesthesia via sober intubation, and the integrity of the transverse ligament was confirmed by the atlantoaxial dynamic test with C‐arm fluoroscopy. Then, pedicle screw internal fixation via the posterior approach was applied to maintain atlantoaxial stability. Results The procedure was performed uneventfully, and the patient was able to move out of bed on the first day after surgery with Philadelphia cervical gear. During a 2‐year follow‐up period, imaging data demonstrated no instability of the atlantoaxial complex. Conclusion Closed manual reduction under C‐arm fluoroscopy is an easy and effective method for PAAD. The integrity of the transverse ligament can be confirmed by C‐arm fluoroscopy through the atlantoaxial dynamic test after reduction. Pedicle screw internal fixation via the posterior approach can provide sufficient stability.

Background: The ulnar collateral ligament (UCL) complex of the elbow plays a primary role in valgus and posteromedial stability of the elbow. The anterior oblique ligament (AOL) of the UCL is believed to provide the majority of resistance to external forces on the medial elbow. The transverse ligament (TL) of the UCL is generally thought to have minimal contribution to the elbow’s overall stability. However, recent studies have suggested a more significant role for the TL. The primary aim of this study was to identify the TL’s contribution to the stability of the elbow joint in determining the joint stiffness and neutral zone variation in internal rotation. Methods: Twelve cadaveric elbows, set at a 90° flexion angle, were tested by applying an internal rotational force on the humerus to generate a medial opening torque at the level of the elbow. The specimens were preconditioned with 10 cycles of humeral internal rotation with sinusoidal torque ranging from 0 to 5 Nm. Elbow stiffness measures and joint neutral zone were first evaluated in its integrity during a final ramp loading. The test was subsequently repeated after cutting the TL at 33%, 66%, and 100% followed by the AOL in the same fashion. Results: The native UCL complex joint stiffness to internal rotation measured 1.52 ± 0.51 Nm/°. The first observable change occurred with 33% sectioning of the AOL, with further sectioning of the AOL minimizing the joint stiffness to 1.26 ± 0.32 Nm/° (P = .004). A 33% resection of the TL found an initial neutral zone variation of 0.376 ± 0.23° that increased to 0.771 ± 0.41° (P

Background: Traumatic posterior atlantoaxial dislocation (PAAD) without fracture of the odontoid process is a rare injury. Closed reduction by skull traction under C‐arm fluoroscopic guidance and open reduction have been reported previously for the treatment of PAAD. Objective: To report a rare case of PAAD without fracture treated by closed manual reduction and posterior fixation. To provide a new method—atlantoaxial dynamic test—for confirming the integrity of the transverse ligament after reduction and evaluate the ideal treatment strategy for traumatic PAAD without fracture of the odontoid process or rupture of the transverse ligament. Method: A 54‐year‐old woman was riding in the passenger seat when her vehicle was rear‐ended by a car. X‐ray and computed tomography (CT) scans were used to diagnose PAAD without a related fracture. Closed manual reduction under C‐arm fluoroscopy was performed after applying general anesthesia via sober intubation, and the integrity of the transverse ligament was confirmed by the atlantoaxial dynamic test with C‐arm fluoroscopy. Then, pedicle screw internal fixation via the posterior approach was applied to maintain atlantoaxial stability. Results: The procedure was performed uneventfully, and the patient was able to move out of bed on the first day after surgery with Philadelphia cervical gear. During a 2‐year follow‐up period, imaging data demonstrated no instability of the atlantoaxial complex. Conclusion: Closed manual reduction under C‐arm fluoroscopy is an easy and effective method for PAAD. The integrity of the transverse ligament can be confirmed by C‐arm fluoroscopy through the atlantoaxial dynamic test after reduction. Pedicle screw internal fixation via the posterior approach can provide sufficient stability. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this basic research study was to clarify the morphological characteristics of the posterior oblique fibers (POL) of the ulnar collateral ligament using a large number of specimens. Methods: This study examined 50 arms from 25 Japanese cadavers. Type classification was performed by focusing on the positional relationship between POL morphology and the joint capsule. The morphological features measured were fiber bundle length, width, and thickness. Results: The POL was classified as follows: Type I, the POL's anterior and posterior edges are located on the surface of the joint capsule and can be separated as a single fiber bundle; Type II-a, the POL anterior edge can be separated, but the posterior edge cannot be separated; Type II-b, the POL posterior edge can be separated, but the anterior edge cannot be separated; and Type III, the POL cannot be separated from the joint capsule. Type I was seen in 23 elbows (46%), Type II-a in 6 elbows (12%), Type II-b in 7 elbows (14%), and Type III in 14 elbows (28%). Conclusion: The results of this study suggested that the POL could be classified into an independent type and an unclear type, and the presence of the unclear type was one of the factors that caused morphological variation. [ABSTRACT FROM AUTHOR]

Atlas fracture occurs in 3%–13% of all cervical spinal injuries and is often associated with other injuries. The factors associated with concomitant transverse ligament disruption and vertebral artery injury remain underexamined. We retrospectively reviewed 97 consecutive cases of atlas fractures. We analyzed demographic and clinic characteristics, including mechanism of injury, fracture type, and associated injuries. We identified factors independently associated with vertebral artery injury and/or transverse ligament disruption. On multivariable analysis, vertebral artery injury was independently, positively associated with injury to the transverse ligament (odds ratio [OR], 8.51 [1.17, 61.72], P = 0.034), associated facial injury (OR, 7.78 [1.05, 57.50]; P = 0.045), intoxication at presentation (OR, 51.42 [1.10, 2408.82]; P = 0.045), and negatively associated with type 3 fractures (OR, 0.081 [0.0081, 0.814]; P = 0.033). There was a trend toward a positive association with a violence mechanism of injury (OR, 33.47 [0.75, 1487.89]; P = 0.070). Transverse ligament injury was independently associated with other injuries to the spine (OR, 13.07362 [2.43, 70.28]; P = 0.003), atlantodental interval (OR, 2.63 [1.02, 6.75]; P = 0.045), lateral mass displacement (OR, 1.78 [1.32, 2.39]; P < 0.001), and male sex (OR, 7.07 [1.47, 34.06]; P = 0.015). There was a trend toward a positive association with injury to the vertebral artery (OR, 5.13 [0.96, 27.35]; P = 0.056). Among patients with atlas fractures, vertebral artery injury and transverse ligament disruption are associated with each other. Mechanism of injury, fracture type, and intoxication at the time of injury were associated with vertebral artery injury, and atlantodental interval and lateral mass displacement are associated with magnetic resonance imaging–confirmed injury to the transverse ligament. [ABSTRACT FROM AUTHOR]

Cervical spine trauma accounts for majority of spinal injuries, and approximately one-third involve the craniocervical junction (CCJ). Due to its high sensitivity, magnetic resonance imaging (MRI) has become the standard tool for imaging suspected ligamentous injuries in an unstable spine and in patients with neurological deficits having a normal CT. The ligamentous anatomy of the CCJ is complex, and thorough knowledge is a prerequisite for accurate interpretation of the MRI findings. This pictorial essay aims to familiarise radiologists with the ligamentous anatomy, mechanisms of injury and MRI appearances of injuries in the cervical spine, with emphasis on the CCJ. [ABSTRACT FROM AUTHOR]

Assessment of transverse ligament (TL) competence in patients with suspected atlantoaxial instability is performed via indirect radiograph measurements or direct TL visualization on magnetic resonance imaging (MRI). Interpretation of these images can be limited by unique patient anatomy or imaging technique variability. We report a novel technique for evaluating TL competence using flexion-extension computed tomography (feCT) scan with 3-dimensional (3D) segmentation and quantitative analysis. feCT scans of 11 patients were segmented to create 3D surface models. Six patients with atlantoaxial pathology were evaluated for possible instability based on clinical examination and imaging findings. The other 5 patients had no clinical or imaging evidence of atlantoaxial injury. Dynamic atlantodental interval (ADI) was calculated using point-to-point voxel changes between flexion and extension 3D models. Magnitude and direction of ADI changes were quantified and compared with available cervical spine flexion-extension radiograph and/or MRI findings. In the 5 patients without evidence of atlantoaxial injury, 94.3% of ADI vector changes were <3.0 mm. In the 3 patients with atlantoaxial pathology but TL competence, 92.4% of ADI vector changes were <3.0 mm. In the 3 patients with atlantoaxial pathology and TL incompetence, only 49.1% of ADI vector changes were <3.0 mm. In addition to the significant atlantoaxial subluxation in these 3 patients, there was significant rotational motion compared with the patients with an intact TL. 3D segmentation and quantitative analysis of feCT scan allow objective indirect assessment of TL integrity. Results are consistent with MRI findings and offer additional biomechanical information regarding the direction and distribution of atlantoaxial motion. [ABSTRACT FROM AUTHOR]

Traumatic posterior atlantoaxial dislocation without odontoid fracture is very rare. Patient prognosis depends on the neurologic symptoms or the extent of damage to the structures. In this case, a 78-year-old-male suffered a posterior atlantoaxial dislocation without odontoid fracture after a traffic accident. We report this case because an exact diagnosis and proper treatment can reduce the neurologic complications in patients with posterior atlantoaxial dislocation.

The medial collateral ligament of the elbow joint consists of the anterior oblique ligament (AOL), posterior oblique ligament (POL), and transverse ligament (TL). This study aimed to clarify the structure of the TL, with a focus on the continuity between the TL and AOL. A total of 42 cadavers (18 males, 24 females) were dissected at Aichi Medical University between 2016 and 2018. Cases of elbow deformity or atrophy were excluded, and 60 elbows (15 males, 15 females) were dissected to assess the fibers of both the TL and AOL using a stereomicroscope. The TL could be detected in all elbows and always continued to the AOL. The TL was classified into 2 types. The TLs continuing to the distal half of the AOL (type I) were observed in 44 elbows (73.3%), whereas the TLs continuing to the entire AOL (type II) were found in 16 elbows (26.7%). Type II TLs were significantly more frequently observed in the elbows of females than in those of males (P =.041). Stereomicroscopic observation revealed that the TL fibers entered perpendicularly to the distal half of the AOL in both types. The TL frequently continues to the distal half of the AOL, but rarely continues to the entire AOL. The TLs continuing to the entire AOL were more frequently detected in the elbows of females than in those of males. The TL possibly contributes to medial elbow stability via its continuity to the AOL. [ABSTRACT FROM AUTHOR]

A retro-odontoid pseudotumor is an uncommon non-neoplastic mass. They are mostly associated with rheumatoid arthritis and atlanto-axial subluxation. The pathogenesis is degeneration of the transverse ligament due to chronic mechanical stress. In this case report, an atlanto-occipital assimilation altered the biomechanics of the cervical spine, causing chronic mechanical stress on the transverse ligament and subsequently the development of a retro-odontoid pseudotumor. This is in accordance with previous studies that have attributed the development of retro-odontoid pseudotumor to a loss of mobility of the cervical spine, in cases without associated rheumatoid arthritis or atlanto-axial subluxation.

Increased range of motion (ROM) at O-C2 after cervical laminoplasty is thought to be a compensatory change due to loss of cervical ROM after surgery. Retro-odontoid pseudotumor in non-RA patients is also caused by loss of ROM at C2-C7 causing mechanical stress on upper cervical spine. The aim of this study was to measure the occipitocervical alignment before and after cervical laminoplasty, and examine the factors associated with postoperative retro-odontoid soft tissue (ROST) enlargement. The study comprised 72 non-RA patients (51 males and 21 females, mean age 65.2 years) who underwent cervical laminoplasty. The cervical angles (O-C1, O-C2, C1-C2, and C2-C7) were measured and ROST thickness was evaluated on mid-sagittal T1-weighted MRI before surgery and 2 years after surgery. Correlations between radiographic changes and postoperative ROST enlargement were examined. The results shows that postoperative ROM and kyphotic angle in flexion position at O-C2 significantly increased, and postoperative ROM and kyphotic angle in flexion position at C2-C7 significantly decreased compared with preoperative values. On stepwise multiple regression analysis, age (beta = 0.273, p < 0.01) and restriction of cervical flexion postoperatively (beta = 0.235, p < 0.01) were independently associated with ROST enlargement. In conclusion, occipitocervical ROM increased and C2-C7 ROM, especially C2-C7 kyphotic angle in flexion, reduced after cervical laminoplasty. The ROST enlargement was associated with reduction in cervical flexion. These results indicate that preservation of cervical ROM, especially kyphotic angle in flexion, after cervical laminoplasty contribute to reduction of mechanical stress at the occipitocervical junction. [ABSTRACT FROM AUTHOR]

Traumatic posterior atlantoaxial dislocation without odontoid fracture is very rare. Patient prognosis depends on the neurologic symptoms or the extent of damage to the structures. In this case, a 78-year-old-male suffered a posterior atlantoaxial dislocation without odontoid fracture after a traffic accident. We report this case because an exact diagnosis and proper treatment can reduce the neurologic complications in patients with posterior atlantoaxial dislocation. [ABSTRACT FROM AUTHOR]

Background Ligaments of the craniocervical junction play a critical role in stabilizing this region. Gerber's ligament has more or less been forgotten and, to our knowledge, never studied. Methods Dissection of the craniocervical junction was performed in 15 fresh frozen cadavers. In the prone position, the posterior elements of the upper cervical vertebrae and occiput were removed. After removing the contents of the spinal canal and posterior cranial fossa, the dura mater and tectorial membrane were reflected. The superior band of the cruciform ligament was reflected. When Gerber's ligament was identified, its attachments and morphometry were recorded. Lastly, Gerber's ligament was observed while range of motion of the craniocervical junction was performed. Results Gerber's ligament was identified in 7 specimens (46.7%). This structure arose anteriorly from the junction of the superior band and transverse part of the cruciform ligament. Gerber's ligament was always found to be just deep to the superior band of the cruciform ligament but traveled more anteriorly to attach onto the posterior aspect of the dens approaching, but not attaching onto, its apex. Mean length was 11 mm, and mean width was 7 mm. Thickness of the ligament was 0.5–1.1 mm. The ligament was found to become taut with minimal rotation of the atlantoaxial joint and extension of the craniocervical junction. Conclusions A good understanding of all ligaments of the craniocervical junction is important to surgeons and physicians treating patients with injury to the upper cervical spine. [ABSTRACT FROM AUTHOR]

Carpal tunnel syndrome (CTS) is a multifactorial compression neuropathy. It is reported to be very common and rising globally. CTS's treatment varies from conservative measures to surgical treatments. Surgery has shown to be an effective method for more severe cases. However few unclear aspects and room for further research and improvements still remains. We performed a narrative literature review on the most up to date progress and innovation in terms of surgical treatments for CTS. The simple algorithm of leaving the choice of the surgical method to surgeons' preference and experience (together with consideration of patients' related factors) seem to be the best available option, which is supported by the most recent metanalysis and systematic reviews. We suggest that surgeons (unless in presence of precise indications towards endoscopic release) should tend to perform a minimally invasive open approach release, favoring the advantage of a better neurovascular structures visualization (and a consequent higher chance to perform a complete release with long term relief of symptoms) instead of favoring an early reduction (in the first postoperative days) of immobilization and pain. Research towards a universally accepted standardization should be aimed for by the researchers, who have failed to date to sufficiently limit bias and limitations., Competing Interests: Conflict-of-interest statement: All the authors declare that they have no conflict of interest., (©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.)