OBJECTIVE: To investigate the correlation between the changes of cervical curvature and atlantoaxial instability. METHODS: The correlation between the changes of cervical curvature and atlantoaxial instability was retrospectively studied in 50 outpatients with abnormal cervical curvature (abnormal cervical curvature group) from January 2018 to December 2019. There were 24 males and 26 females in abnormal cervical curvature group, aged from 18 to 42 years old with an average of(30.62±5.83) years. And 53 patients with normal cervical curvature (normal cervical curvature group) during the same period were matched, including 23 males and 30 females, aged from 21 to 44 years with an average of(31.98±6.11) years. Cervical spine X-ray films of 103 patients were taken in lateral position and open mouth position. Cervical curvature and variance of bilateral lateral atlanto-dental space(VBLADS) were measured and recorded, Pearson correlation coefficient analysis was used to study the correlation between the changes of cervical curvature and atlantoaxial instability. RESULTS: Atlantoaxial joint instability accounted for 39.6%(21/53) in normal cervical curvature group and 84.0%(42/50) in abnormal cervical curvature group. There was significant difference between two groups(P<0.01). VBLADS in abnormal cervical curvature group was (1.79±1.01) mm, which was significantly higher than that in normal cervical curvature group(0.55±0.75) mm(P<0.01). Pearson correlation coefficient analysis showed that the size of cervical curvature was negatively correlated with VBLADS. CONCLUSION Cervical curvature straightening and inverse arch are the cause of atlantoaxial instability, the smaller the cervical curvature, the more serious the atlantoaxial instability.
Adolescent ; Adult ; Atlanto-Axial Joint/diagnostic imaging* ; Cervical Vertebrae/diagnostic imaging* ; Female ; Humans ; Joint Instability/diagnostic imaging* ; Kyphosis ; Male ; Radiography ; Retrospective Studies ; Young Adult

Atlantoaxial dislocation (AAD) is a kind of life-threatening atlantoaxial structural instability and a series of neurological dysfunction caused by common multidisciplinary diseases. The operation risk is extremely high because it is adjacent to the medulla oblongata and the location is deep. With the increase of the number of operations in the upper cervical region, postoperative complications such as failure of internal fixation, non fusion of bone graft and poor prognosis gradually increase.Incomplete primary operation, non fusion of bone graft, infection and congenital malformation are the potential causes. In addition, considering the objective factors such as previous graft, scar formation and anatomical marks changes, revision surgery is further difficult. However, there is currently no standard or single effective revision surgery method. Simple anterior surgery is an ideal choice in theory, but it has high risk and high empirical requirements for the operator;simple posterior surgery has some defects, such as insufficient reduction and decompression;anterior decompression combined with posterior fixation fusion is a more reasonable surgical procedure, but many problems such as posterior structural integrity and multilevel fusion need to be considered.This article reviews the causes and strategies of AAD revision surgery.
Atlanto-Axial Joint/surgery* ; Humans ; Joint Dislocations/surgery* ; Joint Instability/surgery* ; Reoperation/adverse effects* ; Spinal Fusion/methods* ; Treatment Outcome

Objective: To examine the effect of posterior atlanto-axial intraarticular distraction technique as revision surgery for failed posterior fossa decompression in patients with basilar invagination(BI) and atlanto-axial dislocation(AAD). Methods: The clinical data of 13 cases of AAD accompanied with BI treated at Department of Neurosurgery, Xuanwu Hospital, Capital Medical University were retrospectively analyzed. There were 3 males and 10 females,aged (42.6±9.5) years (range:30 to 63 years). All cases had assimilation of atlas and once underwent posterior fossa decompression. Anterior tissue was released through posterior approach followed by cage implantation into facet joint and occipital-cervical fixation with cantilever technique. The clinical results were evaluated using Japanese Orthopedic Association scale(JOA) and the main radiological measurements including atlantodental interval (ADI), the distance of odontoid tip above Chamberlain line(DCL),clivus-canal angle(CCA) and the length of syrinx were collected. Paired sample t test was used to compared the data before and after operation. Results: All patients underwent surgery successfully, the mean surgical time was (187.7±47.4) minutes (range from 116 to 261 minutes). Twenty occipital condyle screws, 26 C2 pedicle screws and 3 occipital plates were implanted. Clinical symptoms improved in all patients. Twelve patients had complete reduction of basilar invagination and atlanto-axial dislocation, 1 achieved near completely reduction of basilar invagination. The postoperative ADI, DCL and CCA significantly improved((4.3±1.1) mm vs. (1.8±0.8) mm, (11.7±5.0) mm vs. (6.4±2.8) mm, (142.4±7.9)° vs. (133.3±7.9)°, all P<0.01).There were 5 cases with syringomyelia before surgery, and shrinkage of syrinx was observed 1 week after surgery in all cases. Eight patients achieved bone fusion 3 months after surgery, all patients achieved bone fusion 6 months after surgery. The JOA score increased from 12.8±2.3 before surgery to 14.8±1.3 one year after surgery, with statistically significant difference (t=4.416, P<0.01).No implant failure, spacer subsidence and infection were observed. Conclusion: In cases of failure posterior fossa decompression of basilar invagination and atlanto-axial dislocation, using posterior atlanto-axial intraarticular distraction and cantilever technique with cage implantation could achieve complete reduction and symptomatic relief.
Atlanto-Axial Joint/surgery* ; Female ; Humans ; Joint Dislocations/surgery* ; Male ; Pedicle Screws ; Platybasia/surgery* ; Reoperation ; Retrospective Studies ; Spinal Fusion/methods*

OBJECTIVE: To explore the treatment strategy and clinical efficacy for os odontoideum complicated with atlantoaxial dislocation. METHODS: The clinical data of 17 patients with os odontoideum complicated with atlantoaxial dislocation surgically treated from January 2006 to January 2015 were retrospectively analyzed, including 7 males and 10 females, aged 17 to 53 (43.1±11.3) years old;course of disease was 3 to 27(10.2±6.9) months. All patients received cranial traction before operation, 12 of 14 patients with reducible dislocation were treated by posterior atlantoaxial fixation and fusion, and 2 patients with atlantooccipital deformity were treated by posterior occipitocervical fixation and fusion;3 patients with irreducible alantoaxial dislocation were treated by transoral approach decompression combined with posterior atlantoaxial fixation and fusion. The operation time, intraoperative blood loss and perioperative complications were recorded. Visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score were used to evaluate the change of neck pain and neurological function. Atlantoaxial joint fusion rate was evaluated by CT scan. RESULTS: The operation time of posterior fixation and fusion ranged from 86 to 170 (92.2±27.5) min, and the intraoperative blood loss was 200-350 (250.7±65.2) ml. No vertebral artery injury and spinal cord injury were recorded. Among the patients underwent atlantoaxial fixation and fusion, 1 patient with reducible dislocation fixed by C CONCLUSION Surgical treatment of os odontoideum complicated with atlantoaxial dislocation can achieve satisfactory results, improve the patient's neurological function and improve the quality of life, however the surgical options needs to be individualized.
Adolescent ; Adult ; Atlanto-Axial Joint/surgery* ; Axis, Cervical Vertebra ; Female ; Humans ; Joint Dislocations/surgery* ; Male ; Middle Aged ; Quality of Life ; Retrospective Studies ; Spinal Fusion ; Treatment Outcome ; Young Adult

OBJECTIVE: To observe the application of modified traction therapy in traumatic atlantoaxial subluxation in adults. METHODS: The clinical data of 31 patients with atlantoaxial subluxation treated from March 2018 to June 2019 were restropectively analyzed. There were 15 males and 16 females, aged from 18 to 68 years old with an average of 39 years old, including 10 cases of 18-40 years, 15 cases of 41-60 years, 6 cases of 51-68 years. The main manifestations of the patients were limited neck movement, pain, and atlantoaxial CT scan showed different degrees of atlantoaxial subluxation. Three dimensional multifunctional traction bed was used for traction for 2 min, relaxation for 10 s. The traction angle starts from the rearward extension of 5°-10° and weight from 3-6 kg. The weight increased by 1 kg every two days until the symptoms were improved. Traction time was 30 min twice a day and 10 days for a course of treatment. One course of treatment was performed in patients with 1-2 mm left and right equal width of atlantoaxial space, and two courses of treatment were performed in patients with 3-4 mm left and right equal width of atlantoaxial space, and the course of treatment could be increased to 3 months in especially patients with serious problems, such as 4 mm left and right equal width of atlantoaxial space and no improvement after conventional treatment. The criteria to evaluate the clinical effect was cure:no pain in the neck, normal range of neck movement, CT showed normal atlantoaxial space and odontoid process was in the middle, patients with normal neck movement were followed up 1 month after the end of treatment;improvement:neck pain was significantly improved and CT showed that the left and right atlantoaxial space was less than 1 mm in equal width. RESULTS: Among the 31 patients, 17 cases were cured by one course of treatment, 11 cases were cured by 2 courses of treatment, and 2 caseswere improved. CONCLUSION The modified traction therapy has obvious effect on adult traumatic atlantoaxial subluxation, especially the subluxation of 3-4 mm equal width in left and right atlantoaxial space, and this method is safe and reliable with good efficacy and the patients without discomfort.
Adolescent ; Adult ; Aged ; Atlanto-Axial Joint ; Female ; Humans ; Joint Dislocations ; Male ; Middle Aged ; Odontoid Process ; Spinal Fusion ; Traction ; Young Adult

OBJECTIVE: To evaluate the effect of bilateral atlantoaxial lamina hook and atlantoaxial joint space screw combined with autologous iliac bone graft on atlantoaxial dislocation caused by acute type I transverse ligament injury in school-age children. METHODS: From February 2006 to February 2019, 8 school-age children with atlantoaxial dislocation caused by acute type I transverse ligament injury were systematically reviewed, including 6 males and 2 females; aged 9 to 12 years old; 8 acute injuries included 4 high-level falls, 2 car accidents and 2 sports injuries; the atlantoaxial interval(ADI) was 5 to 8 mm. Eight cases presented with pain, stiffness, numbness and cervical spine dysfunction in different degrees. Two of them were accompanied by nerve compression and ASIA grade D. The preoperative C₁,₂ angle averaged 20.7° to 23.4°. All patients received cranial traction and surgical treatment after complete reduction or atlantoaxial reduction. The changes of Japanese Orthopaedic Association(JOA) score, space available for the cord(SAC), neck disability index(NDI), ADI, ASIA classification(ASIA) injury classification(1992) and C₁,₂ angle before and after treatment were observed. RESULTS: The average follow-up time was 8 to 156 months. Clinical and radiological follow-up showed that the atlantoaxial joint was completely relieved, the reduction was satisfactory and the arthrodesis was stable. Nerve and vascular injuries associated with this technique were not observed. JOA score, SAC, NDI, C₁,₂ angle of the last follow-up of the children were significantly improved. Two children of ASIA grade D recovered to grade E. CONCLUSIONS Bilateral atlantoaxial lamina hook and atlantoaxial joint space screw combined with autologous iliac bone graft is simple, less bleeding, strong stability and high fusion rate. It is an ideal surgical procedure for acute type I transverse ligament injury with atlantoaxial dislocation in school-age children.
Atlanto-Axial Joint ; surgery ; Bone Screws ; Child ; Female ; Humans ; Joint Dislocations ; Ligaments ; Male ; Spinal Fusion ; Treatment Outcome

OBJECTIVE: Using the CT three-dimensional reconstruction to measure the activity degree of atlanto-occipital joint and the atlantoaxial joint in different directions and its coupling movement in healthy volunteers, and three dimensional motion range of the maximum rotation position of the upper cervical spine of cervical spondylosis patients, and to analyze the differences, verifing the reliability of the method at the meantime. METHODS: From January 2014 to June 2015, 20 healthy adult subjects(healthy adult group), and 26 patients with cervieal spondylosis(cervical spondylosis group) were selected. In healthy adult group, there were 11 males and 9 females, aged from 22 to 26 years old with an average of (24.0±1.2) years, and in cervical spondylosis group, there were 24 males and 2 females, aged from 36 to 72 years old with an average of (52.8±8.6) years. Healthy adults underwent CT examination in neutral position, maximum right rotation, maximum right lateral bending, maximum flexion and extention, and cervical spondylosis patients underwent CT examination in neutral position, maximum right rotation. Then the software Mimics was used to reconstruct occiput (Oc), atlas(C1) and axial(C2) vertebral three-dimensional image. Three virtual non-collinear markers were positioned on prominent structures of foramen magnum, C1 and C2. The 3D spatial coordinates of these virtual anatomical markers entail the definition of an anatomical local coordinate system which represent the position and orientation of the bones. Segmental motions were calculated using Eulerian angle in three major planes, and the difference between cervical spondylosis group and healthy adult group were compared. Due to the inaccuracy in anatomical landmark idenrification, two groups were measured 3 times, and the reliability of the experimental metnod was verified by the intra-group correlation (intra-group ICC) and the inter-group correlation coefficient(inter-group ICC). RESULTS: Reliability verification results:the intra-group ICC and inter-group ICC results were all above 0.90, and the measurement method had high reliability. Three-dimensional activity of the upper cervical spine in healthy adults:the atlanto-occipital joint had(-6.8±1.5)° coupled left lateral bending and (8.9±2.0)° coupled extension in the maximum right rotation position, and the motion of atlanto-occipital joint had low activity[maximum was(5.3±2.6)°] in the remaining 3 positions; the rotation of atlanto-axial joint was(37.9±5.1)°, accounting for 52.34% of the total cervical spine activity[(72.4±5.0)°] in the maximum right rotation position, and rotational motion was still prominent in the remaining three positions. The relative translations of the upper cervical spine in all direction were small. The average axial rotation angle [(62.0±3.4)] ° of the total cervical spine in cervical spondylosis group was significantly lower than that in the healthy adult group, but the mean axial rotation angles of the atlanto-occipital and the atlantoaxial joint were not significantly different from those of the healthy adults(>0.05). CONCLUSIONS The three-dimensional CT reconstruction method has high reliability, which can be applied to measure the movement of spine. The upper cervical spine contributed the most to the direction of rotation, and the movement in all directions are accompanied by coupled motion in the other direction. There was no significant difference in the rotation of the upper cervical spine between cervical spondylosis patients and normal subjects.
Adult ; Aged ; Atlanto-Axial Joint ; Biomechanical Phenomena ; Cervical Vertebrae ; Female ; Humans ; Imaging, Three-Dimensional ; Male ; Middle Aged ; Range of Motion, Articular ; Reproducibility of Results ; Rotation ; Spine ; Tomography, X-Ray Computed ; Young Adult

OBJECTIVE: To assess the clinical results of one stage temporary atlantoaxial segmental fixation and reduction for Grauer type IIB dens fractures in teenagers. METHODS: From February 2009 to April 2015, 19 teenagers with Grauer type IIB dens fractures not amenable to anteiror screw fixation were enrolled and treated using one stage temporary atlantoaxial segmental fixation and reduction without fusion. There were 14 males and 5 females, aged from 14 to 32 years with an average of (24.6±5.0 ) years. The internal fixation was removed after bone healing confirmed by CT scan. At the last follow-up (at least 1 year after internal fixation removal), dynamic CT was used to assess the atlantoaxial rotation activity. Visual analogue scale (VAS) was recorded before the first operation, before the second operation (removal of internal fixation) and at the last follow-up. Neck Disability Index(NDI) was used to evaluate the efficacy before the second operation (removal of internal fixation) and the last follow-up. RESULTS: After operation, 2 patients developed the symptoms of occipital nerve stimulation such as numbness and pain in the occipitocervical region, and were treated with drugs such as dehydration and neurotrophic drugs, and the symptoms were relieved after 1 to 2 months. All the internal fixations were removed and all the patients were followed up more than 1 year, with time ranging from 18 to 25 months and an average of (21.47±2.41) months. The time of bone fusion after operation was 6 to 10 months with the mean of(8.21±1.27) months. Secondary surgical removal of internal fixation were performed immediately after fracture healing without internal fixation failure. The symptoms of neck pain improved significantly after operation, VAS score decreased from 6.74±0.65 before operation to 0.42±0.51 at the last follow-up after the second operation (removal of internal fixation), with statistically significant differences(<0.01). The NDI value decreased from (10.58±2.04)% before the second operation (removal of internal fixation) to (3.79±2.23)% at the last follow-up after the second operation (removal of internal fixation), with statistically significant difference(<0.01). At the last follow-up after the second operation (removal of internal fixation), dynamic CT showed that the unilateral rotation of the atlantoaxial spine reached (15.73±5.57)° to the left, (15.55±5.78)° to the right, and the overall rotation of the atlantoaxial spine was (31.28±10.71)°. CONCLUSIONS One stage temporary atlantoaxial segmental fixation and reduction for the treatment of Grauer type IIB dens fractures not amenable to anteiror screw fixation in teenagers can avoid the loss of atlantoaxial rotation function caused by atlantoaxial fusion, and to some extent retain the rotation activity of atlanto-axial joint.
Adolescent ; Adult ; Atlanto-Axial Joint ; Bone Screws ; Female ; Fracture Fixation, Internal ; Fractures, Bone ; Humans ; Male ; Odontoid Process ; Treatment Outcome ; Young Adult

joint disk-like structure at the anterior component of the median atlanto-axial joint. At mid-term, the disk-like structure was thick (0.1–0.15 mm) relative to the sizes of bones surrounding the joint. However, it did not completely separate the joint cavity, and was absent in the inferior and/or central part of the cavity. This morphology was similar to the so-called fibroadipose meniscoid of the lumbar zygapophysial joint that is usually seen in adults. In mid-term fetuses, there was evidence suggesting that a mesenchymal tissue plate was separated from a roof of the joint cavity. In late-stage fetuses, the thickness (less than 0.15 mm) was usually the same as, or less than that at mid-term, and the disk-like structure was often flexed, folded and fragmented. Therefore, in contrast to the zygapophysial meniscoid as a result of aging, the present disk-like structure was most likely a temporary product during the cavitation process. It seemed to be degenerated in late-stage fetuses and possibly also in newborns. Anomalies at the craniocervical junction such as Chiari malformations might accompany this disk-like structure at the median atlanto-axial joint even in childhood.]]>
Adult ; Aging ; Atlanto-Axial Joint ; Fetus ; Humans ; Infant, Newborn ; Joints ; Zygapophyseal Joint

Torticollis is an abnormal, asymmetric head or neck position which usually caused by imbalance of paracervical muscles. The traumatic torticollis can be caused by following events; atlantoaxial rotatory subluxation, atlantoaxial dislocation, cervical vertebral fractures, and injury to the cervical musculature. Especially, acute traumatic atlantoaxial rotatory subluxation usually presents limitation of cervical range of motion without pain or neurologic deficit. We report a case of a 58 year-old man who developed the acute atlantoaxial rotatory subluxation right after the chiropractic therapy, which induced the limitation of cervical range of motion to 52.5% of normal range. The magnetic resonance image revealed the facture of the odontoid process and the partial injury in transverse ligaments of the atlas. He underwent intramuscular botulinum toxin injection and 10 days of continuous cervical traction 15 hours a day using a 5 kg weight. The range of the cervical motion restored up to 90.2% of normal range.
Atlanto-Axial Joint ; Botulinum Toxins ; Chiropractic ; Dislocations ; Head ; Ligaments ; Muscles ; Neck ; Neurologic Manifestations ; Odontoid Process ; Range of Motion, Articular ; Reference Values ; Torticollis ; Traction