Atlanto-Axial Joint ; injuries ; surgery ; Decompression, Surgical ; Fracture Fixation, Internal ; methods ; Humans ; Joint Dislocations ; surgery ; Traction

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

Adolescent ; Atlanto-Axial Joint ; surgery ; Child ; Child, Preschool ; Female ; Humans ; Joint Diseases ; surgery ; Joint Dislocations ; therapy ; Male

OBJECTIVESTo explore the clinical features of traumatic atlantoaxial instability combined with subaxial cervical spinal cord injury (CSCI), and to analyze the feasibility, indication and therapeutic effects of anterior-posterior approach in such cases.

METHODSFrom March 2004 to September 2009, 16 cases with this trauma were admitted and surgically treated in our department. Before surgery, skull traction was performed. Posterior atlantoaxial pedicle screw internal fixation and bone graft fusion were conducted to manage traumatic atlantoaxial instability. As for subaxial CSCI, anterior cervical corpectomy or discectomy decompression, bone grafting and internal fixation with steel plates were applied.

RESULTSAll operations were successful. The average operation time was 3 hours and operative blood loss 400 ml. Satisfactory reduction of both the upper and lower cervical spine and complete decompression were achieved. All patients were followed up for 12 to 36 months. Their clinical symptoms were improved by various levels. The Japanese Orthopaedic Association (JOA) scores ranged from 10 to 16 one year postoperatively, 13.95+/-2.06 on average(improvement rate equal to 70.10%). X-rays, spiral CT and MRI confirmed normal cervical alignments, complete decompression and fine implants'position. There was no breakage or loosening of screws, nor exodus of titanium mesh or implanted bone blocks. The grafted bone achieved fusion 3-6 months postoperatively and no atlantoaxial instability was observed.

CONCLUSIONSTraumatic atlantoaxial instability may combine with subaxial CSCI, misdiagnosis of which should be especially alerted and avoided. For severe cases, one stage anterior-posterior approach to decompress the upper and lower cervical spine, together with reposition, bone grafting and fusion, as well as internal fixation can immediately restore the normal alignments and stability of the cervical spine and effectively improve the spinal nervous function, thus being an ideal approach.

Aged ; Atlanto-Axial Joint ; injuries ; surgery ; Female ; Humans ; Joint Instability ; diagnosis ; surgery ; Male ; Middle Aged ; Spinal Cord Injuries ; diagnosis ; surgery

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*

OBJECTIVETo compare the anti-rotation biomechanical performances of wire and various cable fixation devices currently used in the posterior Brooks instrumentation for atlantoaxial instability.

METHODSIn this experiment,six specimens of the atlantoaxial complex (Occipital-C3) were used. The models of the normal complex,unstable complex (type II odontoid fracture) and fixed complex were established. On the WD-5 mechanics experimental machine,the parameters including the strength and rigidity of anti-rotation were quantified for the normal complex (group N),the atlantoaxial instability complex (group M), the new type Titanium cable (group A), Atlas titanium cable (group B), Songer Titanium cable (group C), stainless wire(group D).

RESULTSThe max strength of A, B, C, D groups was 12.5, 11.3, 11.52, 11.55 N x m respectively, the max rigidity was 58.81, 53.17, 54.11, 54.35 N x cm/deg respectively. The strength and rigidity of anti-rotation, compare to the unstable atlantoaxial complex which were fixed by the new double locking Titanium cable fixation system were superior to those of normal complex, instability complex, Songer or Atlas Titanium cable (P < 0.05).

CONCLUSIONHaving been changed the locking method, the anti-rotation biomechanical characteristics of the new type double locking Titanium cable fixation system are superior or similar to the traditional Songer or Atlas Titanium cable.

Atlanto-Axial Joint ; physiopathology ; surgery ; Biomechanical Phenomena ; Bone Wires ; Humans ; Joint Instability ; physiopathology ; surgery ; Orthopedic Fixation Devices ; Rotation

OBJECTIVETo research the correlation between surgical treatment for atlantoaxial dislocation and dredging Governor vessel.

METHODSFrom June 2004 to June 2010,113 patients were reviewed, including 65 males and 48 females, with the mean age of 42.6 years (ranged, 8 to 64 years). All the patients were classified and treated by TOI clinical classification which included traction and decompression and reduction, and inter fixation fusion by surgery. The SAC (space available for the cord), Governor vessel Yuzu score, JOA score, NDI score (cervical spine dysfunction index) before treatment were compared with those of after treatment.

RESULTSThe SAC in each group before treatment were (13.34 +/- 3.21), (10.43 +/- 2.42), (7.89 +/- 3.14), (10.50 +/- 0.71) mm respectively, the last follow-up of (16.02 +/- 1.42), (15.34 +/- 1.87), (14.49 +/- 1.58), (12.50 +/- 0.71) mm; Governor vessel Yuzu score before treatment were (8.37 +/- 1.87), (6.87 +/- 1.35), (5.17 +/- 1.13), (7.50 +/- 0.71) respectively, the last follow-up of (10.59 +/- 0.94), (10.25 +/- 1.01), (8.41 +/- 1.31), (9.0 +/- 0); JOA, NDI score significantly improved compared with that of before treatment.

CONCLUSIONAtlantoaxial dislocation confirmed and treated by TOI clinical classification can effectively relieve the nerve function and Governor vessel Yuzu syndrome, and show that surgical treatment is closely related with dredging the Governor vessel.

Adolescent ; Adult ; Atlanto-Axial Joint ; surgery ; Child ; Female ; Humans ; Joint Dislocations ; surgery ; Male ; Middle Aged ; Retrospective Studies

OBJECTIVETo compare the biomechanical performances of different wires and cable fixation devices in posterior instrumentation for atlantoaxial instability, and test the effect of different fixation strengths and fixation approaches on the surgical outcomes.

METHODSSix specimens of the atlantoaxial complex (C0-C3) were used to establish models of the normal complex, unstable complex (type II odontoid fracture) and fixed complex. On the wd-5 mechanical testing machine, the parameters including the strength and rigidity of anti-rotation, change and strength of stress, and stability were measured for the normal complex, atlantoaxial instability complex, the new type titanium cable fixation system, Atlas titanium cable, Songer titanium cable, and stainless wire.

RESULTSThe strength and rigidity of anti-rotation, change and strength of stress, stability of flexion, extension and lateral bending of the unstable atlantoaxial complex fixed by the new double locking titanium cable fixation system were superior to those of the Songer or Atlas titanium cable (P<0.05) and medical stainless wire (P<0.05). Simultaneous cable fastening on both sides resulted in better fixation effect than successive cable fastening (P<0.05). Better fixation effect was achieved by fastening the specimen following a rest (P<0.05).

CONCLUSIONSThe fixation effects can be enhanced by increased fastening strengths. The new type double locking titanium cable fixation system has better biomechanical performance than the conventional Songer and Atlas titanium cables. Fastening the unstable specimens after a rest following simultaneous fastening of the specimen on both sides produces better fixation effect.

Atlanto-Axial Joint ; physiopathology ; surgery ; Biomechanical Phenomena ; Bone Wires ; Cadaver ; Humans ; Internal Fixators ; Joint Instability ; physiopathology ; surgery ; Orthopedic Fixation Devices

In order to provide anatomical basis for transoral approach (TOA) in dealing with the ventro lesions of craniocervical junction, and the design and application of artificial atlanto-odontoid joint, microsurgical dissecting was performed on 8 fresh craniocervical specimens layer by layer through transoropharyngeal approach. The stratification of posterior pharyngeal wall, course of vertebral artery, adjacent relationship of atlas and axis and correlative anatomical parameters of replacement of artificial atlanto-odontoid joint were observed. Besides, 32 sets of atlanto-axial joint in adults' fresh bony specimens were measured with a digital caliper and a goniometer, including the width of bony window of anterior arch of atlas, the width of bony window of axis vertebra, the distance between superior and inferior two atlas screw inserting points, the distance between two axis screw inserting points etc. It was found that the width of atlas and axis which could be exposed were 40.2+/-3.5 mm and 39.3+/-3.7 mm respectively. The width and height of posterior pharyngeal wall which could be exposed were 40.1+/-5.2 mm and 50.2+/-4.6 mm respectively. The distance between superior and inferior two atlas screw inserting points was 28.0+/-2.9 mm and 24.0+/-3.5 mm respectively, and the distance of bilateral axis screw inserting points was 18.0+/-1.2 mm. The operative exposure position through TOA ranged from inferior part of the clivus to the superior part of the C3 vertebral body. Posterior pharyngeal wall consisted of 5 layers and two interspaces: mucosa, submucosa, superficial muscular layer, anterior fascia of vertebrae, anterior muscular layer of vertebrae and posterior interspace of pharynx, anterior interspace of vertebrae. This study revealed that it had the advantages of short operative distance, good exposure and sufficient decompression in dealing with the ventro lesions from the upper cervical to the lower clivus through the TOA. The replacement of artificial atlanto-odontoid joint is suitable and feasible. The design of artificial atlanto-odontoid joint should be based on the above data.
Atlanto-Axial Joint/*anatomy & histology ; Atlanto-Axial Joint/*surgery ; Bone Plates ; Bone Screws ; Cadaver ; Cervical Vertebrae/*anatomy & histology ; Cervical Vertebrae/surgery ; Equipment Design ; Internal Fixators ; Joint Prosthesis ; Models, Anatomic ; Odontoid Process/*surgery ; Prosthesis Design

The present of atlanto-axial pedicle screw fixation through posterior approach provide a new remedy for treating instability of pillow and cervical. A lot of researches have reported feasibility of atlanto-axial pedicle screw fixation, the results showed that it had advantages of easily exposure, less blood loss, shorter operative time, especially in treating as remedy fixation for atlanto-axial joint screw, atlas lateral mass screws and pedicle screw caused by injuries of tumor,inflammation and trauma. If not done properly, it can cause serious complications, such as iatrogenic fracture,injuries of vertebral artery and cervical spinal cord. Therefore,the safty and effectiveness of atlanto-axial pedicle screw fixation may be focus of research.
Atlanto-Axial Joint ; surgery ; Bone Screws ; utilization ; Cervical Atlas ; surgery ; Fracture Fixation, Internal ; instrumentation ; methods ; trends ; Humans ; Spinal Fractures ; surgery