Biomechanical evaluation of four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs

ABSTRACT Purpose: This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs. Methods: In total, 28 identical atlantoaxial joint models were created by digital printing from computed tomography images of a dog, and the specimens were divided into four groups of seven. In each group, a different technique for ventral stabilization of the atlantoaxial joint was performed: transarticular lag screws, polyaxial screws, multiple screws and bone cement (polymethylmethacrylate-PMMA), and atlantoaxial plate. After the stabilization technique, biomechanical evaluation was performed under ventral flexion load, both with a predefined constant load and with a gradually increasing load until stabilization failure. Results: All specimens, regardless of stabilization technique, were able to support the predefined load without failing. However, the PMMA method provided significant more rigidity (p ≤ 0.05) and also best resisted the gradual increase in load, supporting a significantly higher maximum force (p ≤ 0.05). There was no statistical difference in flexural strength between the transarticular lag screws and plate groups. The polyaxial screws method was significantly less resistant to loading (p ≤ 0.05) than the other groups. Conclusions: The PMMA technique had biomechanical advantages in ventral atlantoaxial stabilization over the other evaluated methods.

Axial instrument strategy for atlantoaxial dislocation with complex artery variation / 中华骨科杂志

Objective:To evaluate the axial instrument strategy for atlantoaxial dislocation with complex vertebral artery variation.Methods:A total of 55 patients with atlantoaxial dislocation who underwent surgical treatment from January 2019 to December 2021 were retrospectively analyzed, including 14 males and 41 females, aged 54.0±12.8 years (range, 22-78 years). Among these patients, 10 patients with unilateral vertebral artery high ride with contralateral vertebral artery occlusion, 30 patients with bilateral vertebral artery high ride with single dominant vertebral artery, 15 patients with bilateral vertebral artery high ride. All patients underwent posterior reduction and internal fixation. Visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score were used to evaluate the postoperative efficacy.Results:All patients completed the surgery successfully with a follow-up time of 14.6±5.5 months (range, 6-24 months). C 2 pedicle screw fixation was performed on the non-dominant side of unilateral vertebral artery high ride and the non-dominant side of bilateral vertebral artery high ride with one dominant vertebral artery (40 vertebraes). The dominant side of unilateral high vertebral artery and bilateral high vertebral artery with one dominant vertebral artery was fixed with C 2 medial "in-out-in" screw (10 vertebraes), C 2 isthmus screw (21 vertebraes), C 2 without screw (9 vertebraes) only extended the fixed segment. For bilateral vertebral artery high ride patients, one side was used C 2 "in-out-in" pedicle screws (right 10 vertebraes, left 5 vertebraes), and the other side was fixed with C 2 medial "in-out-in" screw (8 vertebraes), C 2 isthmus screw (5 vertebraes), C 2 without screw only extended the fixed segment (2 vertebraes). The JOA scores were 8.5±1.8, 13.9±1.3, and 14.4±1.1 preoperatively, 6 months postoperatively, and at the final follow-up, respectively, with statistically significant differences ( F=279.40, P<0.001). JOA at 6 months postoperatively and at the final follow-up was greater than preoperatively, and the differences were statistically significant ( P<0.05), whereas the differences in JOA scores at 6 months postoperatively and at the final follow-up was not statistically significant ( P>0.05). Preoperative, 6 months postoperatively and final follow-up cervical VAS scores were 3.7±1.9, 2.1±0.9 and 1.6±1.0, respectively, with statistically significant differences ( F=39.53, P<0.001). The cervical VAS at 6 months postoperatively and at the last follow-up was less than that before surgery, and the differences were statistically significant ( P<0.05). Cervical VAS scores at 6 months postoperatively were greater than at the last follow-up, with a statistically significant difference ( P<0.05). Conclusion:For patients with atlantoaxial dislocation with complex vertebral artery variation, C 2 lateral "in-out-in" screw, C 2 medial "in-out-in" screw, isthmus screw fixation or C 2 without screw only extended the fixed segment can obtain good clinical efficacy.

Research progress of Chiari malformation type I and atlantoaxial instability / 中华骨科杂志

Chiari malformation (CM) is a group of congenital cerebellar tonsillar hernia malformations involving the craniocervical junction. Chiari malformation type I (CMI) is the most common in clinic, however its pathogenesis is still unclear, and there is no consensus on the surgical treatment standard of CMI. At present, the most widely accepted is the theory of posterior fossa incompatibility, so doctors at home and abroad use posterior fossa decompression (PFD) and posterior fossa compression with duraplasty (PFDD) as the gold standard for surgical treatment, and have their own experience and technical improvement. However, the volume of the posterior cranial fossa in some patients is no different from that in healthy people, and about 30% of the patients with CMI have poor results after posterior cranial fossa decompression. As a result, this operation cannot treat all patients with CMI. In recent years, with the development of imaging, the progress of diagnostic technology and the deepening of understanding of CM, some studies have shown that CMI may be related to atlantoaxial instability, and proposed that CMI is the secondary factor of atlantoaxial instability, and atlantoaxial fusion is the standard of surgical treatment, which has caused great controversy in academic circles. Different clinical research results of scholars support or oppose this theory: some studies have shown that the clinical symptom relief rate of patients with CMI treated with atlantoaxial fusion is 96.9%; another study showed that 70% of patients with CMI underwent atlantoaxial fusion had improved neurological function, but the overall postoperative effect was not satisfactory. In short, CMI is related to many diseases and its clinical manifestations are complex. Therefore, individualized management and treatment should be carried out in combination with the clinical manifestations and auxiliary examination results of patients.

Efficacy evaluation of cluster nursing in robot-assisted surgery for the treatment of reducible atlantoaxial dislocation / 中华创伤杂志

Objective:To explore the effect of cluster nursing in robot-assisted surgery for the treatment of reducible atlantoaxial dislocation.Methods:A retrospective cohort study was conducted to analyze the clinical data of 41 patients with reducible atlantoaxial dislocation treated by robot-assisted surgery in Honghui Hospital affiliated to Xi′an Jiaotong University from January 2019 to December 2021, including 28 males and 13 females; aged 18-79 years [(45.2±10.3)years]. Ninteen patients received cluster nursing (cluster nursing group), with operating room nursing team set up on the basis of routine nursing and performed cluster nursing in line with evidence-based medicine. Twenty-two patients received routine nursing (routine nursing group). The operation time, intraoperative blood loss, frequency of intraoperative C-arm fluoroscopy, time of drainage tube placement and chief surgeon′s satisfaction for nursing were compared between the two groups. The degree of pain was evaluated by pain numerical score (NRS) at 12 hours, 24 hours, 48 hours, 72 hours, 1 month and 3 months after operation and at the last follow-up. The neck disability index (NDI) was assessed at 1 day before operation, 1 month after operation, 3 months after operation and at the last follow-up. The complications were observed.Results:All patients were followed up for 12-18 months [(16.7±3.7)months]. The operation time, intraoperative blood loss, frequency of C-arm fluoroscopy and time of drainage tube placement in cluster nursing group were (82.9±10.4)minutes, (105.9±11.8)ml, (3.8±0.6)times and (1.5±0.4)days, while those in routine nursing group were (125.7±12.8)minutes, (208.4±13.8)ml, (9.7±2.3)times and (3.6±0.6)days, respectively (all P<0.01). The chief surgeon′s satisfaction for nursing was 94.7% (18/19) in cluster nursing group and was 68.2% (15/22) in routine nursing group ( P<0.05). The NRS in cluster nursing group was (6.2±0.4)points, (6.0±0.7)points, (4.9±1.1)points, (2.7±0.5)points, (1.9±0.4)points, (1.8±0.4)points and (1.5±0.3)points at 12 hours, 24 hours, 48 hours, 72 hours, 1 month and 3 months after operation and at the last follow-up, while it was (7.6±0.6)points, (6.8±1.2)points, (5.8±1.5)points, (4.2±0.8)points, (3.4±0.7)points, (2.6±0.5)points and (2.2±0.5)points in routine nursing group ( P<0.05 or 0.01). There was no significant difference in the NDI between the two groups at 1 day before operation, but the NDI in cluster nursing group was 20.6±4.5, 14.6±2.8 and 10.7±2.5 at 1 month and 3 months after operation and at the last follow-up, while it was 26.9±4.1, 18.7±3.3 and 13.7±1.7 in routine nursing group (all P<0.01). There was no hematoma, infection or implant-related complications in both groups .Conclusion:For robot-assisted surgery in the treatment of reducible atlantoaxial dislocation, cluster nursing is associated with shortened operation time and time of drainage tube placement, decreased intraoperative blood loss and frequency of intraoperative fluoroscopy, increased chief surgeon′s satisfaction for nursing, reduced pain and accelerated functional recovery.

Fijación con tornillos transarticulares C1-2 combinada con técnica de Gallie en luxación atloaxoidea / C1-2 transarticular screw fixation combined with Gallie technique in atloaxial dislocation

RESUMEN Introducción: existen múltiples técnicas quirúrgicas para tratar la inestabilidad del complejo atlantoaxial. La fijación con tornillos transarticulares C1-2 (técnica de Magerl) ha mostrado altos índices de fusión, y puede ser combinada con los sistemas de alambrado descritos inicialmente, para garantizar mayor estabilidad al constructo. Presentación de caso: masculino, 62 años, que luego de una caída de dos metros, es traído a la institución con dolor cervical y con imposibilidad para mover las extremidades. Al examen neurológico, presentaba un grado B en la American Spinal Injury Classiffication Scale. Se diagnostica fractura odontoidea conminuta y luxación atloaxoidea. Se le aplica tracción cervical con lo que se logra la alineación vertebral. Se planifica tratamiento quirúrgico mediante técnica de Magerl. Ante trayectoria subóptima del tornillo inicial, se combina con fusión atloaxoidea posterior, mediante técnica de Gallie. Se mantuvo inmovilización externa durante dos semanas. Al egreso hospitalario, el paciente logra la deambulación, aunque con disparesia braquial con predominio distal. En estudios radiológicos evolutivos, no se observa fallo del sistema de instrumentación. Conclusiones: en este caso la utilización de la técnica de Gallie, ante la malposición de uno de los tornillos transarticulares C1-2, permitió conservar la estabilidad del constructo.

ABSTRACT Introduction: Multiple surgical techniques exist to treat instability of the atlantoaxial complex. Transarticular C1-2 screw fixation (Magerl's technique) has shown high fusion rates, and can be combined with the initially described wiring systems to guarantee greater stability to the construct. Case presentation: male, 62 years old, who after a two-meter fall, was brought to the institution reporting cervical pain and inability to move the limbs. On neurological examination, he had a grade B on the American Spinal Injury Classiffication Scale. A comminuted odontoid fracture and atloaxial dislocation were diagnosed. Cervical traction was applied and vertebral alignment was achieved. Surgical treatment was planned using Magerl's technique. Given the suboptimal trajectory of the initial screw, it was combined with posterior atloaxoid fusion, using Gallie technique. External immobilization was maintained for two weeks. At hospital discharge, the patient achieved ambulation, maintaining brachial dysparesis with distal predominance. In evolutionary radiological studies, no failure of the instrumentation system was observed. Conclusions: In our case, the use of the Gallie technique, in view of the malposition of one of the C1-2 transarticular screws, allowed preserving the stability of the construct.

Comparison of Jefferson-fracture reduction plate and micro titanium plate in the transoral single-segment fixation of unstable atlas fractures / 中华创伤骨科杂志

Objective:To compare Jefferson-fracture reduction plate (JeRP) and micro titanium plate in the transoral single-segment fixation of unstable atlas fractures.Methods:From January 2008 to December 2020, 45 patients with unstable atlas fracture were treated by single-segment fixation through an oral approach with a JeRP or a micro titanium plate at Department of Orthopedic Surgery, General Hospital of Southern Theatre Command. They were 24 males and 21 females, aged from 15 to 67 years. By the Gehweiler classification, 11 atlas fractures were type Ⅰ and 34 type Ⅲ; by the American Spinal Injury Association (ASIA) classification, the spinal cord injury was grade D in 7 cases and grade E in 38 cases; by the Dickman classification, the atlas transverse ligament injury was type Ⅰ in 4 cases and type Ⅱ in 11 cases. Of the patients, 26 were treated by transoral single-segment fixation with a JeRP and 19 by transoral single-segment fixation with a micro titanium plate. The 2 groups were compared in terms of baseline data, operation time, blood loss, hospital stay, visual analog scale (VAS) for neck pain and atlas lateral mass displacement (LMD) before operation and at the last follow-up, and intraoperative and postoperative complications.Results:The 2 groups were comparable because there was no significant difference between them in the preoperative general data ( P>0.05). All patients were followed up for 12 to 55 months (mean, 21.8 months). Wound dehiscence or infection was observed in none of the patients after operation. About 12 months after operation, all fractures achieved bony union, neck pain basically disappeared, and neck movement had no obvious limitation. The hospital stay was (13.9±2.2) d for the JeRP group and (14.2±2.9) d for the micro titanium plate group, showing no significant difference between the 2 groups ( P>0.05). The operation time was (203.5±173.4) min and the blood loss (167.3±138.6) mL in the JeRP group, significantly more than those in the micro titanium plate group [(121.5±50.5) min and (98.4±57.2) mL] ( P<0.05). In the JeRP group, the preoperative LMD was (6.7±1.7) mm and the preoperative VAS score (6.8±1.0) points, significantly higher than the last follow-up values [(0.7±0.6) mm and (0.7±0.6) points] ( P<0.05). In the micro titanium plate group, the preoperative LMD was (6.6±1.5) mm and the preoperative VAS score (6.7±0.9) points, significantly higher than the last follow-up values [(0.9±0.6) mm and (0.8±0.7) points] ( P<0.05). However, there was no significant difference in the preoperative or the last follow-up comparison between the 2 groups ( P>0.05). Implant loosening was observed in one patient in the JeRP group while foreign body sensation in the throat was reported in one patient after operation in the micro titanium plate group. Conclusions:Both JeRP and micro titanium plate in the transoral single-segment fixation can lead to effective treatment of unstable atlas fractures. Compared with JeRP, the micro titanium plate can effectively shorten operation time and reduce blood loss due to its smaller size and lower incision.

Locked-in syndrome after traumatic atlantoaxial subluxation: a case report / Síndrome do encarceramento decorrente de subluxação atlantoaxial traumática: relato de caso / Síndrome de enclaustramiento por subluxación atlantoaxoidea traumática: informe de caso

ABSTRACT Traumatic atlanto-axial subluxation is a rare and underdiagnosed condition due to its high rate - reported to be between 60 and 80% - of early mortality. Its diagnosis takes into account the trauma mechanism, precise analyses of the imaging tests and the clinical presentation of the patient. This article describes a rare presentation of atlanto-axial subluxation associated with craniocervical dislocation as a case of locked-in syndrome. Level of evidence V; Retrospective observational study - Case report.

RESUMO Subluxação atlantoaxial traumática é uma condição de diagnóstico raro e subestimado, devido a sua alta taxa - descrita entre 60% e 80% - de mortalidade precoce. Seu diagnóstico leva em conta o mecanismo do trauma, as análises precisas dos exames de imagem e a apresentação clínica do paciente. Este artigo relata um quadro raro de subluxação atlantoaxial associada à luxação craniocervical como um caso de síndrome do encarceramento. Nível de evidência V; Estudo observacional retrospectivo - Relato de caso.

RESUMEN La subluxación atlantoaxoidea traumática es una afección rara y subdiagnosticada debido a su alta tasa - descrita entre el 60 y el 80%-de mortalidad temprana. Su diagnóstico tiene en cuenta el mecanismo del traumatismo, los análisis de imagen precisos y la presentación clínica del paciente. Este artículo informa de una rara condición de subluxación atloaxoidea asociada a una dislocación craniocervical como un caso de síndrome de enclaustramiento. Nivel de evidencia V; Estudio observacional retrospectivo - Informe de caso.

Correlation of craniovertebral parameters with the retropharyngeal space in posterior C1-C2 arthrodesis / Correlação dos parâmetros craniovertebral com o espaço retrofaríngeo na artrodese posterior C1-C2 / Correlación de los parámetros craneovertebral con el espacio retrofaríngeo en la artrodesis posterior C1-C2

ABSTRACT Introduction/Objective: The craniovertebral junction (CVJ) requires a detailed evaluation, as the changes in alignment caused by surgery can affect adjacent structures in a secondary way. Examples of these effects are dyspnea or dysphagia after posterior occipitocervical arthrodesis, due to decreased caliber of the oropharynx. These changes can be identified perioperatively by several radiographic parameters that aim to predict possible postoperative respiratory complications. Such complications appear to be related to the narrowest oropharyngeal airway space (nPAS), and may also occur following atlantoaxial (C1-C2) arthrodesis. This work aims to correlate the variation in CVJ alignment parameters before and after C1-C2 arthrodesis with the variation in nPAS. Methods: Patients who underwent posterior C1-C2 arthrodesis between 2011 and 2019 at the National Institute of Traumatology and Orthopedics (INTO) were included in the study, totaling 26 patients. The parameters evaluated included cervical lordosis, C1-C2 angle, slope of C2, Occipito-C2 angle (O-C2), pharyngeal inlet angle (PIA), pharyngeal tilt angle (PTA), occiput and external acoustic meatus to axis angle (O-EAa), cranial transverse motion against C2 angle (C2TA), axial tilt (AT) and the percentage of change in nPAS (%∆nPAS). Results: A correlation was observed between the change in C1-C2 angle, O-C2, PTA, C2TA and the %∆nPAS. Conclusion: The change in cervical alignment and CVJ parameters is correlated with %∆nPAS and should, therefore, be evaluated before and after atlantoaxial fusion as a means of predicting a possible respiratory complication. Level of Evidence: III; Cross sectional study .

RESUMO Introdução/Objetivo: A junção craniovertebral (JCV) deve ter avaliação detalhada já que as alterações de alinhamento ocasionadas pela cirurgia podem acometer estruturas adjacentes de forma secundária. Exemplos desses efeitos são dispneia ou disfagia depois de artrodese occipitocervical posterior, por diminuição no calibre da orofaringe. Essas alterações podem ser identificadas no perioperatório por diversos parâmetros radiográficos que visam predizer possíveis complicações respiratórias pós-operatórias. Tais complicações parecem estar relacionadas com o menor espaço da via orofaríngea (nPAS, narrowest oropharyngeal airway space) e também podem ocorrer depois de artrodese atlantoaxial (C1-C2). Este trabalho tem como objetivo correlacionar a variação dos parâmetros de alinhamento da JCV no pré e pós-operatório de artrodese C1-C2 com a variação do nPAS. Métodos: Foram incluídos no estudo pacientes submetidos à artrodese posterior C1-C2 entre 2011 e 2019 no Instituto Nacional de Traumatologia e Ortopedia (INTO), totalizando 26 indivíduos. Os parâmetros avaliados incluíram lordose cervical, ângulo C1-C2, inclinação de C2, ângulo Occipito-C2 (O-C2), ângulo de entrada da faringe (PIA, pharyngeal inlet angle), ângulo de inclinação da faringe (PTA, pharyngeal tilt angle), ângulo do eixo occipital e meato acústico externo (O-EAa, occiput and external acoustic meatus to axis angle), movimento transversal craniano contra o ângulo C2 (C2TA, cranial transverse motion against C2 angle), inclinação axial (AT, axial tilt) e porcentagem de mudança no nPAS (%∆nPAS) resultado: Foi observada correlação entre a mudança dos ângulos C1-C2, OC2, PTA, C2TA e a %∆nPAS. Conclusão: A alteração do alinhamento cervical e dos parâmetros da JCV está correlacionada com a %∆nPAS e deve, portanto, ser avaliada antes e depois da artrodese atlantoaxial como forma de prever uma possível complicação respiratória. Nível de Evidência III; Estudo transversal .

RESUMEN Introducción/Objetivo: La unión craneocervical debe ser objeto de una evaluación detallada, ya que los cambios de alineación provocados por la cirugía pueden afectar de forma secundaria a las estructuras adyacentes. Ejemplos de estos efectos son la disnea o la disfagia después de la artrodesis occipitocervical posterior debido a la disminución del calibre de la orofaringe. Estos cambios pueden identificarse en el período perioperatorio por varios parámetros radiográficos que pretenden predecir posibles complicaciones respiratorias postoperatorias. Estas complicaciones parecen estar relacionadas con el espacio orofaríngeo más estrecho (nPAS, narrowest oropharyngeal airway space) y también pueden producirse tras la artrodesis atlantoaxial (C1-C2). Este trabajo tiene como objetivo correlacionar la variación de los parámetros de alineación de la unión craneocervical en el período pre y postoperatorio de la artrodesis C1-C2 con la variación del nPAS. Métodos: Se incluyeron en el estudio los pacientes sometidos a artrodesis posterior C1-C2 entre 2011 y 2019 en el Instituto Nacional de Traumatología y Ortopedia (INTO), totalizando 26 individuos. Los parámetros evaluados incluyeron lordosis cervical, ángulo C1-C2, inclinación de C2, ángulo Occipito-C2 (O-C2), ángulo de entrada de la faringe (PIA, pharyngeal inlet angle),, ángulo de inclinación de la faringe (PTA, pharyngeal tilt angle) ), ángulo del eje occipital y el meato acústico externo (O-EAa, occiput and external acoustic meatus to axis angle), movimiento transversal craneal contra el ángulo C2 (C2TA, cranial transverse motion against C2 angle), inclinación axial (AT, axial tilt)) y porcentaje de cambio en el nPAS (%∆nPAS). Resultado: Se observó una correlación entre el cambio de los ángulos C1-C2, O-C2, PTA, C2TA y %∆nPAS. Conclusión: El cambio en la alineación cervical y los parámetros de la unión craneovertebral se correlaciona con el %∆nPAS y por lo tanto, debe evaluarse antes y después de la artrodesis atlantoaxial como forma de predecir una posible complicación respiratoria. Nivel de Evidencia III; Estudio transversal .

Restore irreducible atlantoaxial dislocation by anterior joint release through wedge-end-mini-channel and posterior fixation / 中华骨科杂志

Objective:To investigate the feasibility and safety of a novel surgery, to restore irreducible atlantoaxial dislocation (IAAD) by atlantoaxial joint release through wedge-end-mini-channel (via conventional Smith-Robinson anterolateral approach) combined with posterior fixation.Methods:Five patients with IAAD from May 2013 to December 2021 were retrospectively analyzed, including 3 males and 2 females, aged 44.6±9.0 years (range, 38-61). All the patients received atlantoaxial joint release through wedge-end-mini-channel (via conventional Smith-Robinson anterolateral approach) combined with posterior fixation. The Japanese Orthopedic Association (JOA) score and improvement rate, American Spinal Injury Association (ASIA) grade, atlantodental interval (ADI) and reduction rate, space available for the cord (SAC) and fusion of bone graft were measured and recorded.Results:The follow-up time was 80.0±23.1 months (range, 34-96 months). The surgery time of anterior joint release was 105±23 min (range, 75-135 min), and the total surgery time was 234±42 min (range, 212-276 min). The blood loss of anterior joint release was 80±16 ml (range, 60-100 ml), and the total blood loss was 123±34 ml (range, 85-150 ml). JOA scores were 6.6±0.9 before surgery, 11.2±0.4 at post-operative 1 month, and 14.8±0.80 at the last follow-up ( F=97.28, P<0.001), and the improvement rate of the last follow-up JOA score was 79.1%±7.64%. The ASIA grade were three cases of 'C’ level and two cases of 'D’ level before surgery, and two cases of 'D’ level and three cases of 'E’ level at the last follow-up. The ADI before surgery, at post-operative 6 months and the last follow-up were 9.56±1.07 mm, 1.46±0.39 mm and 1.48±0.29 mm, respectively ( F=206.54, P<0.001). The reduction rate of last follow-up ADI was 84.6%±1.4%. The SAC before surgery, at post-operative 6 months and last follow-up were 10.3±1.83 mm, 20.12±1.19 mm and 20.06±1.25 mm, respectively ( F=44.47, P<0.001). Grafted bone fuse was seen in 3 cases at post-operative 6 months, and 5 cases at post-operative 12 months. The only complication was unexpected titanium rod fracture in 1 case at post-operative 14 months. Conclusion:For IAAD, the novel surgery of atlantoaxial joint release through wedge-end-mini-channel (via conventional Smith-Robinson anterolateral approach) combined with posterior fixation could achieve well joint restoration and neural function improvement, which was a safe and effective procedure.

Long-term outcomes of posterior release and reduction for irreducible atlantoaxial dislocation / 中华骨科杂志

Objective:To evaluate the long-term outcomes of posterior release, reduction, fixation, and fusion for irreducible atlantoaxial dislocation (AAD).Methods:Between January 2005 and June 2016, a total of 31 patients with irreducible AAD who had received posterior approach surgery were included. Among them, there were 13 males and 18 females, the average age was 39.1±13.5 years (range 9-72 years). The clinical data of the eligible individuals were collected and analyzed. Neck disability index (NDI) and Japanese Orthopaedic Association (JOA) scores were recorded to evaluate the recovery of neck and neurological functions. The atlantodental interval (ADI), clivus-canal angle (CCA), and cervico-medullary angle (CMA) were measured to evaluate the reduction of AAD. C 0-C 2 angle and C 2-C 7 angle were measured to evaluate the recovery of cervical alignment. For individuals with basilar invagination, the distances from the tip of odontoid process to Chamberlain line and Wackenheim line were measured to assess the reduction in the vertical direction. The duration of bony fusion and complications were also analyzed. Results:The mean follow-up period was 82.7±26.4 months (range 61-170 months). In terms of functional scores, the NDI dropped from 43.41%±11.60% before surgery to 12.19%±6.97% at the six months follow-up, and 9.45%±7.51% at the last follow-up ( F=89.56, P<0.001). The JOA increased from 9.48±2.41 points before surgery to 14.71±1.42 points at the six months follow-up, and 14.97±1.47 points at the last follow-up ( F=52.89, P<0.001). Regarding the horizontal and vertical dislocations, the ADI decreased from 9.16±2.32 mm before surgery to 1.39±1.04 mm at the six months follow-up, and 1.29±1.08 mm at the last follow-up ( F=189.61, P<0.001). The distance from the tip of odontoid process to Chamberlain line decreased from 11.15±4.35 mm before surgery to 2.03±2.83 mm at the six months follow-up, and 2.15±3.02 mm at the last follow-up ( F=37.58, P<0.001). The distance from the tip of odontoid process to Wackenheim line reduced from 6.81±2.57 mm before surgery to -2.23±1.58 mm at the six months follow-up, and -2.27±1.58 mm at the last follow-up ( F=122.16, P<0.001). For the amelioration of the compression on medulla and spinal cord, the CCA increased from 113.68°±12.67° before surgery to 143.39°±7.38° at the six months follow-up, and 142.39°±7.13° at the last follow-up ( F=67.13, P<0.001). The CMA increased from 115.71°±13.69° before operation to 145.58°±10.78° at the last follow-up ( F=41.44, P<0.001). Regarding the curvature of the cervical spine, the C 0-C 2 angle recovered from 1.94°±15.82° before surgery to 14.84°±6.45° at the last follow-up ( F=11.97, P<0.001), and the C 2-C 7 angle ameliorated from 27.26°±8.49° before operation to 19.26°±5.44° at the last follow-up ( F=11.13, P<0.001). Bony fusion was achieved in all cases, the fusion time was 9.71±2.55 months (range 5-15 months). A total of five complications occurred in the cases (two cerebrospinal fluid leakages, one deep infection, one transient neurologic deficit, and one dysphagia). They were all cured with corresponding treatments. In the last follow-up, none of the cases developed failure of internal fixation or re-dislocation. Conclusion:Posterior approach release, reduction, fixation and fusion technique is a safe and efficient surgical strategy with favorable long-term follow-up outcomes for irreducible AAD.

Correlative analysis of cervical curvature and atlantoaxial instability / 中国骨伤

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.

Imaging study of simple Chiari malformation type I and atlantoaxial instability / 中华骨科杂志

Objective:To investigate the relationship between simple Chiari malformation type I (CMI) and atlantoaxial instability from the imaging point of view.Methods:A retrospective analysis were performed on 46 patients diagnosed with simple CMI from January 2014 to December 2020. Forty-six normal people matched for age and sex were selected as the normal control group, while 30 patients with atlantoaxial dislocation were selected as the dislocation group. The degree of atlantoaxial joint degeneration in each group was assessed according to Weishaupt degeneration grading; the atlantoaxial joint angulation angle was measured in the control group of patients with simple CMI; and the sagittal imaging parameters of cervical spine X-ray were measured, including C 0-C 1 Cobb angle, C 0-C 2 Cobb angle, C 1-C 2 Cobb angle, C 1-C 7 Cobb angle, C 2-C 7 Cobb angle, C 7 Slope, C 2 Tilt, spino cranial angle (SCA), and C 2-C 7 sagittal vertebral axis (SVA). All radiographic parameters were measured twice independently by two spine surgeons, and intraclass correlation coefficient (ICC) were determined to demonstrate intra- and inter-observer reliability. Results:ICC ranged between 0.842 and 0.974 in the current study, demonstrating "excellent" reliability of radiographic measurements. No significant difference was noted regarding age and the distribution of genders among the three groups. There were significant differences in the distribution of Weishaupt degeneration grading of atlantoaxial joints between simple CMI, normal and dislocation group ( H=53.68, P<0.001 on the left side; H=43.39, P<0.001 on the right side). There were significant differences in the degree of atlantoaxial joint degeneration between the normal group and dislocation group (left, Z=6.60, P<0.001; right, Z=6.29, P<0.001); There were significant differences in the degree of atlantoaxial joint degeneration between the normal group and simple CMI patients (left, Z=5.31, P<0.001; right, Z=4.13, P<0.001); There were significant differences in the degree of atlantoaxial joint degeneration between simple CMI and dislocation group (left, Z=3.20, P=0.001; right, Z=3.15, P=0.002). There were significant difference in the angulation angle of the atlantoaxial articular surface between the normal group and simple CMI patients (left, Z=3.32, P<0.001; right, Z=5.74, P<0.001). There were significant differences in C 0-C 1 Cobb angle ( t=2.41, P=0.018), C 1-C 7 Cobb angle ( t=2.88, P=0.005), C 2-C 7 Cobb angle ( t=3.29, P=0.001), and C 2-C 7 SVA ( t=2.87, P=0.005) between the normal group and simple CMI patients, but there was no significant difference in other parameters. Conclusion:The degree of atlantoaxial joint degeneration in patients with simple CMI is higher than that in normal people, the angulation angle is larger, and the cervical lordosis is larger, suggesting that there may be atlantoaxial joint instability. This study provides further evidence that Chiari malformation type I is associated with atlantoaxial instability.

Surgical strategies of atlantoaxial dislocation in mucopolysaccharidosis IVa / 中华骨科杂志

Objective:To discuss the surgical strategies of atlantoaxial dislocation in children with mucopolysaccharidosis IVA.Methods:8 cases of atlantoaxial dislocation in children with mucopolysaccharidosis IVA treated with posterior atlantoaxial reduction, decompression, bone graft and internal fixation from April, 2019 to October, 2020 were retrospectively analyzed, including 6 males and 2 females, aged 6.2±3.1 years (range, 2-10 years). All the 8 children had lower limb weakness and walking instability, and some of them could not even stand and walk, and all of them had odontoid hypoplasia, atlantoaxial dislocation and systemic skeletal dysplasia. Measures, including American Spinal injury Association (ASIA) grade, modified atlanto-dental interval (mADI) and reduction rate, screw placement type and fusion of bone graft, were recorded and analyzed.Results:The follow-up time was 17.8±7.4 months (range, 8-27 months). The total operation time was 144.0±43.1 mins (range, 90-220 min) and the blood loss during the surgery was 89.1±55.1 ml (range, 15-180 ml). The ASIA grade were 3 cases of "C" level, 4 cases of "D" level and 1 case of "E" level before the operation, and 1 case of "C" level, 1 case of "D" level and 6 cases of "E" level at the latest follow-up. The mADI reduced from 7.38±2.62 mm pre-surgery to 2.50±1.60 mm ( t=5.71, P=0.001). The reduction rate of the latest follow-up mADI was 65.0%±26.3%. 31 pedicle screws were inserted, including 26 Type I screws (83.9%), 4 Type II screws (12.9%) and 1 Type III screw (3.2%), and no injury of spinal cord or blood vessels were observed associated with the Type III screw. One unilateral axial lamina screw was used in 1 case. 5 patients showed fusion (autogenous bone) 6 months after the surgery, 2 patients got fusion (allogeneic bone) 1 year after the surgery, and other patients showed bone graft resorption (allogeneic bone) at the latest follow-up. One patient developed type II respiratory failure on the night of operation and recovered after rescue. Other patients had no complications such as vascular and nerve injury, screw loosening and so on. Conclusion:The majority of children with type IVa mucopolysaccharidosis are accompanied by absence of odontoid process. If such children are complicated with atlantoaxial dislocation and cervical spinal canal stenosis resulting in cervical spinal cord injury, timely surgical intervention should be carried out. Posterior atlantoaxial fusion is a safe and effective surgical method. As children have the characteristics of multi-system involvement, multi-disciplinary cooperation may be needed to ensure perioperative safety.

Cervical anterior approach atlantodentoplasty for the treatment of irreducible atlantoaxial dislocation complicated with bony abnormality of atlanto-dental joint / 中华骨科杂志

Objective:To evaluate the clinical efficacy of cervical anterior approach atlantodentoplasty for the treatment of irreducible atlantoaxial dislocation complicated with bony abnormality of atlanto-dental joint.Methods:Retrospective analysis was conducted to study the clinical data of 31 patients with irreducible atlantoaxial dislocation complicated with bony abnormality of atlanto-dental joint, including 7 males and 24 females; age ranged from 23 to 74 years, with an average of 49.0±12.0 years. All patients underwent cervical anterior approach soft tissue release, atlantodentoplasty and one-stage posterior occipito-cervical fixation and fusion. Twenty-one patients with atlantodental osteoarthritis underwent simplex atlantodental osteophyte resection, 5 patients with anterior tubercle hypertrophy of atlas and 5 patients with anterior tubercle hypertrophy of atlas and atlantodental osteoarthritis underwent atlantodental osteophyte resection and partial anterior tubercle resection. The operation time and blood loss of anterior procedure and total procedure were recorded. The anterior tubercle thickness (ATT), the atlantodental interval (ADI)were recorded before and 1 week after the operation. The available space of the cord (SAC), clivus-canal angle (CCA), cervicomedullaryangle (CMA), and the Japanese Orthopaedic Association (JOA) scores were recorded before the operation, 1 week, 3 months and 12 months after the operation, and at the last follow-up. The JOA improvement rate at the last follow-up was calculated, the time of postoperative bone graft fusion was recorded, and the complications were observed.Results:All patients were followed up for 12-60 months, with an average of 34.5±13.8 months. The operation time of anterior cervical atlantodentoplasty was 120.9±15.9 min, and the overall operation time was 315.1±31.4 min; The blood loss of anterior procedure was 101.2±31.2 ml, and that of overall procedure was 372.7±56.0 ml. The one week postoperative ATT (7.4±1.6 mm) of patients with anterior tubercle partial resection of atlas was lower than that before operation 10.8±1.5 mm ( t=4.94, P=0.001). The one week postoperative ADI 0.9±1.2 mm decreased compared with the preoperative ADI 8.3±2.2 mm ( t=17.91, P<0.001). The preoperative SAC was 10.4±2.8 mm, which increased to 19.2±3.6 mm one week after operation and 19.4±3.7 mm ( F=41.31, P<0.001) at last follow-up. The preoperative CCA was 119.4°±17.9°, which increased to 142.6°±13.0° one week after operation and 141.6°±12.2° ( F=35.86, P<0.001) at last follow-up. The preoperative CMA was 121.7°±14.1°, which increased to 148.9°±9.4° one week after operation and 149.4°±9.0° ( F=52.07, P<0.001) at last follow-up. The preoperative JOA score was 12.0±2.6, which was 14.3±1.3 one week after operation and 15.9±1.0 ( F=23.81, P<0.001) at last follow-up. JOA improvement rate was 78.9%±17.1%, while 23 cases were excellent (74.2%), 8 cases were good (25.8%), and the excellent and good rate was 100%; Thd fusion time of grafted bone was 5.7±1.5 months with the fusion rate of 100%; There were 12 patients with dysphagia after operation, all of which relieved spontaneously 5-10 days after operation; There were 3 cases of irritating choking after drinking or eating, and 2 cases were gradually alleviated 3-5 days after operation. One case was complicated with aspiration pneumonia due to stubborn choking, which gradually alleviated after 1 month of nasal feeding. No hardware failure or reduction loss, no serious complications such as esophageal injury, cerebrospinal fluid leakage, incision infection or vertebral artery injury occurred. Conclusion:Cervical anterior approach atlantodentoplasty for the treatment of irreducible atlantoaxial dislocation complicated with bony abnormality of atlanto-dental joint can anatomically reduce the atlantoaxial joint, and the clinical effect is satisfactory.

Transoral stepped atlantoaxial release theory for irreducible atlantoaxial dislocation / 中华骨科杂志

Objective:To investigate the clinical efficacy of different grade transoral atlantoaxial release for the treatment of irreducible atlantoaxial dislocation.Methods:From January 2010 to December 2019, 297 patients with irreducible atlantoaxial dislocation treated by different grade releases were retrospectively analyzed, including 132 males and 165 females, aged 42.3±12.14 years (range, 10-63 years). All cases were treated by different grade releases, Grade I (196, 66.0%), Grade II (54, 18.2%), Grade III (28, 9.4%) and Grade IV (19, 6.4%). The American Spinal Injury Association (ASIA) grade and Japanese Orthopedic Association (JOA) score were recorded as the clinical evaluation index. The clivus-canal angle (CCA) and cervico-medullary angle (CMA) were measured to evaluate the reduction. The surgery time, blood loss, duration of bony fusion and complications were also analyzed.Results:The follow-up time was 14.8±10.2 months (range, 9-36 months). The surgery time of Grade I-IV were 2.02±0.35 min, 3.00±0.36 min, 4.07±0.96 min and 5.24±0.83 min, respectively ( F=385.43, P<0.001), blood loss was 84.08±27.21 ml, 153.61±31.36 ml, 268.93±48.94 ml and 444.21±109.51 ml, respectively ( F=582.39, P<0.001). The preoperative ASIA motor score of Grade I-IV were 83.85±6.68, 84.06±5.47, 84.07±5.99 and 85.00±4.11, respectively. The last follow-up were 98.34±2.38, 98.67±1.79, 98.86±1.58 and 98.32±2.11, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative JOA score of Grade I-IV were 11.44±1.73, 11.59±1.72, 11.61±1.47 and 11.32±1.80, respectively. The last follow-up were 16.22±1.00, 16.28±1.02, 16.14±1.04 and 16.16±1.07, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative CCA of Grade I-IV were 110.19°±8.76°, 112.48°±7.66°, 106.61°±6.54° and 109.05°±7.79°, respectively. The last follow-up were 140.22°±8.04°, 141.86°±7.04°, 142.35°±8.62° and 140.15°±6.49°, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative CMA of Grade I-IV were 113.48°±9.54°, 116.03°±8.38°, 109.55°±7.13°, and 112.46°±8.33°, respectively. The last follow-up were 144.28°±7.75°, 146.40°±6.98°, 145.81°±8.27° and 143.24°±6.36°, respectively, with statistically significant differences from preoperative ( P<0.05). Solid bony fusion was obtained except for 3 cases, the fusion time was 9.71±2.55 months (range 3-14 months). Altogether 33 complications occurred in all cases (11.1%), including 3 fusion failure, 3 cerebrospinal leak, 3 wound infection, 2 death (1 case caused by cerebrospinal leak), 11 pharyngeal discomfort, 4 postoperative pain surrounding iliac crest, and 8 malunion of iliac crest. Conclusion:Transoral stepped atlantoaxial release theory could provide guidelines for atlantoaxial dislocation treatment, and make the transoral release technique more effective and safer.

Treatment strategy and curative effect analysis of os odontoideum complicated with atlantoaxial joint dislocation / 中国骨伤

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.

Retro-odontoid pseudotumor: a poorly recognized alteration of the craniocervical junction

SUMMARY INTRODUCTION Retro-odontoid pseudotumor (ROP) is a rare disease that affects the atlantoaxial joint and, in general, is associated with local biomechanical alterations that may or may not cause instability. METHODS Descriptive study of the literature available in databases MEDLINE/PubMed, LILACS, and Scopus. The research was conducted in April 2019. DISCUSSION ROP is, possibly, a syndromic designation that encompasses a significant variety of diseases of the atlantoaxial joint. There are different pathophysiological mechanisms implicated in its genesis. The patients, almost in their entirety, present with severe myelopathy, and most of them are treated surgically, with the posterior decompression being the most commonly used method, with or without arthrodesis. Evolution is usually favorable. CONCLUSION The ROP is still poorly recognized as a differential diagnosis between the diseases of the cranial-cervical junction. The information available in the literature analyzed was based mainly on the study of reports or case series; therefore, it is insufficient to define conducts with a high level of scientific evidence.

RESUMO INTRODUÇÃO O pseudotumor retro-odontoide (PRO) é uma patologia rara que acomete a articulação atlantoaxial e, em geral, está associada a alterações biomecânicas locais que podem ou não causar instabilidade. METODOLOGIA Estudo descritivo da literatura disponível nas bases de dados Medline/PubMed, Lilacs e Scopus. A pesquisa foi realizada em abril de 2019. DISCUSSÃO O PRO é, possivelmente, uma designação sindrômica que abrange uma variedade significativa de doenças da articulação atlantoaxial. Existem diferentes mecanismos fisiopatológicos implicados em sua gênese. Os pacientes, quase em sua totalidade, apresentam quadro de mielopatia grave e a maioria deles é tratada cirurgicamente, sendo a descompressão posterior o método mais utilizado, com ou sem artrodese. A evolução costuma ser favorável. CONCLUSÃO O PRO ainda é pouco reconhecido como diagnóstico diferencial entre as doenças da junção crânio-cervical. As informações disponíveis na literatura analisada foram baseadas principalmente no estudo de relatos ou séries de casos, sendo, portanto, insuficientes para definir condutas com alto nível de evidência científica.

Clinical observation of tuina manipulations for tic disorders in kids / 针灸推拿医学（英文版）

Objective: To observe the clinical efficacy of tuina manipulations in treating different types of tic disorders (TD). Methods: Eligible TD patients were classified into three types, transient tic disorders (TTD), chronic multiple tic disorders (CMTD) and Tourette syndrome (TS), according to their disease duration and severity. The three types of children were treated with the same tuina manipulations. Changes in the Yale global tic severity scale (YGTSS) score, effective rate for tic, and cervical spine imaging examination results (including asymmetry of the lateral atlanto-dental interval, broadened anterior atlanto-dental interval, C2 spinous process deviation, occipito-atlanto-axial flexion/ extension instability) were observed after 1-month and 3-month treatments respectively. Results: The YGTSS score changed significantly after 1-month and 3-month treatments compared with that before treatment (both P<0.01); the effective rate for TD was 46.6％ and 86.7％ respectively after 1-month and 3-month treatments; there were significant differences comparing the effective rate for tic between different types of TD after 1-month and 3-month treatments (all P<0.05); comparing the effective rate for tic after 1-month treatment with that after 3-month treatment for the same type, the intra-group differences were statistically significant [TTD group (P<0.01), CMTD group (P<0.01), TS group (P<0.05)]; the abnormal parameter rates in neck imaging examination after 3-month treatment were significantly different from those before treatment (all P<0.01). Conclusion: Tuina manipulation is effective for TTD, CMTD and TS. It can correct the abnormal alterations of patients' cervical vertebrae, and its efficacy for TTD is most significant.

Application of electric drill drive technique in atlantoaxial posterior screw trajectory preparation / 中华创伤杂志

Objective@#To investigate the application effect of electric drill drive in the preparation of atlanto-axial posterior screw trajectory.@*Methods@#A retrospective case-control study was conducted to analyze the clinical data of 29 patients with atlanto-axial fracture and dislocation admitted to the Lanzhou University Second Hospital from February 2016 to March 2019. There were 19 male and 10 females, aged from 10 to 72 years, with an average of 44.6 years. All patients received posterior atlantoaxial screw fixation. Electric drill drive was adopted in 14 patients to prepare the screw trajectory (electric drill group), and bare hand technique was used in 15 patients (bare hand group). In the electric drill group, 28 atlantal lateral screws and 28 axial pedicle screws were implanted; in the free hand group, 30 atlantal lateral screws and 30 axial pedicle screws were implanted. The trajectory preparation time and intraoperative blood loss between the two groups were compared. After the operation, the X-ray films and 3D CT were taken to observe the lateral mass of atlas as well as the position, loosening or rupture, and bone healing of axial pedicle screws, and complications. Frankel grading and visual analogue scale (VAS) at the last follow-up were compared between the two groups.@*Results@#All patients were followed up for 3 to 36 months, with an average of 21 months. The electric drill group took significantly shorter time in preparing both atlantal and axial pedicle screw trajectories than the bare hand group [(8.8±4.2)minutes ∶(16.5±9.7)minutes; (4.1±1.2)minutes∶ (6.1±3.2)minutes] (P<0.05). There was no significant difference in intraoperative blood loss between the electric drill group and the bare hand group [(54.2±32.0)ml ∶ (58.0±28.4)ml] (P>0.05). In the electric drill group, the penetration rate of atlantal screws was 0, the complete position rate was 96% (27/28), and the good rate of screw placement was 100% (28/28), superior to 23% (7/30), 73% (22/30) and 73%(22/30) in the bare hand group (P<0.05). In terms of the axial screws, in the electric drill group, the panetration rate was 4% (1/28), the complete position rate was 82% (23/28), and the good rate of screw placement was 96% (27/28), superior to 10% (3/30), 70% (21/30) and 93% (28/30) in the bare hand group (P>0.05). There were no complications such as cerebrospinal fluid leakage, spinal cord injury, cerebellar infarction, loosening and fracture of internal fixation, and nonunion of bone. At the last follow-up, Frankel grading and VAS of the two groups were improved to different degrees (P<0.05), but there was no significant difference between the two groups (P>0.05).@*Conclusion@#For atlantoaxial fracture and dislocation, preparation of atlantoaxial internal fixation screw trajectories by electric power can significantly shorten the operation time and improve the accuracy of atlas screw placement.

Posterior atlantoaxial joint axial release, bone grafting and internal fixation for irreducible atlantoaxial dislocation with partial reduction / 中华创伤杂志

Objective@#To investigate the efficacy of posterior atlantoaxial joint axial release, bone grafting and internal fixation for the treatment of irreducible atlantoaxial dislocation (IAAD) with partial reduction.@*Methods@#A retrospective case-control study was conducted to analyze the clinical data of 42 patients with IAAD admitted to Henan Provincial People's Hospital from January 2014 to October 2017. There were 17 males and 25 females, aged from 12 to 72 years [(47.2±11.3) years]. After more than 50% reduction by high weight skull traction, 18 patients underwent posterior atlantoaxial joint axial release, reduction, bone grafting and fusion with internal fixation (Group A), and 24 patients underwent anterior transoral or retropharyngeal release, reduction, posterior bone grafting and fusion with internal fixation (Group B). The operation time, intraoperative blood loss, preoperative and postoperative anterior atlantodental interval (ADI), clivus-canal angle (CCA), cervicomedullary angle (CMA), and Japanese Orthopaedic Association (JOA) scores between the two groups were compared. The improvement rate of JOA scores at the last follow-up of the two groups and the atlantoaxial joint fusion rate at 3 months and 6 months after surgery were calculated and compared. The complications were recorded.@*Results@#All patients were followed up for 12 to 40 months with an average of 24.6 months. Group A had significant decreases in operation time [(138.1±25.6) minutes ∶(242.8±38.1) minutes] and intraoperative blood loss [(179.3±48.7)ml ∶(218.2±42.6)ml] compared with Group B (P<0.05). There were significant differences between the ADI, CCA, CMA and JOA scores before operation and during the last follow-up in both Group A and Group B (P<0.05), but there was no significant difference between the two groups in terms of these scores (P>0.05). The JOA scores in Group A were excellent in eight patients, good in eight patients, and fair in two patients, with the improvement rate of 89%. The JOA scores in Group B were excellent in 13 patients, good in eight patients, and fair in three patients, with the improvement rate of 87% (P>0.05). In Group A, the atlanto-axial joint fusion rate was 83% at 3 months and 100% at 6 months postoperatively; in Group B, the fusion rate was 79% at 3 months and 100% at 6 months postoperatively (P > 0.05). There was no failure of internal fixation or loss of reduction in both groups.@*Conclusion@#Posterior atlantoaxial joint axial release, bone grafting and fusion with internal fixation can be used to treat the partially reducible IAAD through a single approach. The reduction effect was comparable to that of anterior transoral or retropharyngeal release, bone grafting and fusion, with less operation time and intraoperative blood loss.