Microendoscopic anterior approach for irreducible atlantoaxial dislocation: surgical techniques and preliminary results.

STUDY DESIGN: Surgical techniques and preliminary results. OBJECTIVE: To describe and evaluate the safety and efficacy of a new minimal invasive technique for the irreducible atlantoaxial dislocation (IADD). SUMMARY OF BACKGROUND DATA: Endoscope has been widely used in minimal invasive spinal surgery. However, there are no clinical reports regarding anterior approach for IADD in the literature. METHODS: Ten consecutive patients with IADD were treated by anterior release with microendoscopic aide and subsequently reduction, anterior transarticular screw fixation and morselized autologous bone grafts. There were 3 cases of odontoid dysplasia, 4, chronic odontoid fracture, 1, odontoid absence, 1 fasilar impression, and 1 malunion of odontoid fracture. According to Symon and Lavender's classification of disability, 6 cases were moderate disability, 3 severe nonbedbound, and 1 severe bedridden. The procedure was performed by the same surgeon (Yong-Long Chi). RESULTS: The new technique was performed successfully in all cases. All the patients underwent transarticular screw fixation and anterior morselized autograft fusion. The average operation time was 120 min (range, 90 to 150 min) and the mean estimated blood loss was 150 mL (range, 100 to 250 mL). Postoperative radiographs demonstrated that 9 cases restored anatomic position and 1 had partial reduction. According to the postoperative computed tomography all the screws were appropriately placed. Follow-up after surgery, longest is 16 months and minimal 8 months with a mean of 12 months, neurologic status was improved in all patients. There was no loss of fixation and solid fusion was achieved in all cases. CONCLUSIONS: Surgical technique of microendoscopic anterior release, reduction, fixation, and fusion is safe and reliable minimally invasive for treating IADD.

Projection of the Most Anterior Line of the Spinal Canal on Lateral Radiograph: An Anatomic Study for Percutaneous Kyphoplasty and Percutaneous Vertebroplasty.

ABSTRACTPurpose: To measure the projection of the most anterior line of the spinal canal on lateral radiographs of the vertebra (C3-L5) and evaluate the efficacy of the safety line (SL) in preventing intraspinal cement leakage in percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP). Materials and Methods: Fifteen adult dry-bone spine specimens were analyzed. The projection of the SL was viewed on lateral radiographs. The distance between the SL and the posterior vertebral body line (PVBL) was measured. Two groups of patients were treated by PKP, and cement injection was stopped either before the PBVL (group 1) or before the SL (group 2) under lateral fluoroscopy. The rate of cement leakage was compared between the two groups. Results: The largest distance between the SL and PVBL was at L1 (5.22 ± 0.62 mm). From L1 to L5, the distance decreased progressively to 1.05 ± 0.64 mm. Similar variation was also observed from L1 to T1 (0.19 ± 0.18 mm). The postoperative computed tomography scan was more sensitive and accurate in detecting intraspinal leakage than radiography in group 1 (p = 0.000); however, there was no significant difference in sensitivity or accuracy between methods in group 2 (p = 0.063). The rate of intraspinal cement leakage was significantly higher in group 1 than group 2 (p = 0.000). Conclusions: The operator should frequently check to ensure that cement injection has stopped upon reaching the SL. Surgeons may benefit from this quantitative anatomical study of PKP and PVP.

Acceptable Chin-Brow Vertical Angle for Neutral Position Radiography: Preliminary Analyses Based on Parameters of the Whole Sagittal Spine of an Asymptomatic Chinese Population.

OBJECTIVE: We sought to acquire the whole sagittal spine parameters and investigated the acceptable chin-brow vertical angle (CBVA) for neutral position radiography in an asymptomatic Chinese population. METHODS: The parameters measured in 257 asymptomatic volunteers included CBVA, occipital slope, orbital tilt, occipital incidence, C0-C2 Cobb angle, C2-C7 Cobb angle, C1-C7 Cobb angle, C2-C7 sagittal vertical axis and absolute rotation angle, cervical tilt, cranial tilt, T1 slope, and thoracic kyphosis, and others. We used Pearson correlation analyses to find relationships between CBVA and other variables. The subjects were divided into 5 groups according to the CBVA percentile: group A, 0%-20% CBVA; group B, 20%-40% CBVA; group C, 40%-60% CBVA; group D, 60%-80% CBVA; and group E, 80%-100% CBVA. We used analysis of variance to analyze differences among the 5 groups. RESULTS: Orbital tilt, Occipital incidence, C1-C7 Cobb angle, C2-C7 sagittal vertical axis, and cranial tilt all increased with increasing CBVA (P < 0.001). The occipital slope, C2-C7 Cobb angle, C2-C7 absolute rotation angle, cervical tilt, T1 slope, and thoracic kyphosis decreased with decreasing CBVA (P < 0.05). No correlations between other sagittal parameters and the CBVA were found. A slight deviation was found in groups B-D, with a greater deviation in groups A, C, and E. CONCLUSIONS: An acceptable range of -1.5° to 5.8° is recommended for the CBVA for cervical radiography in the neutral position. When spinal surgeons evaluate the cervical plane, the effects of the CBVA deviation on cervical curvature must be considered.

Anterior endoscopically assisted bone grafting for iatrogenic distraction of odontoid fracture after percutaneous anterior screw fixation: A case report.

RATIONALE: The complication of iatrogenic distraction of odontoid fracture after anterior screw fixation has not been reported in the literature. We treated the patient with endoscopically assisted bone grafting with good results. The new technique was not reported in the management of odontoid fracture or nonunion before. PATIENT CONCERNS: A 22-year-old man presented with neck pain after a motorcycle crash. The cervical spine radiograph and computed tomographic scan demonstrated the base of dens displaced 2 mm anteriorly. DIAGNOSES: Radiographic images showed a type II odontoid fracture. INTERVENTIONS: The patient was treated by percutaneous anterior screw fixation. The postoperative radiograph and CT demonstrated an iatrogenic distraction of the odontoid with a gap of 6 mm.The follow-up radiograph did not show any sign of bone union 1 month and a half later. A revision surgery was given by anterior endoscopically assisted bone grafting. The patient was encouraged to sit out of bed immediately after the surgery with the protection of a soft cervical collar for 3 months. OUTCOMES: No complications such as neural structures or vascular injuries were found. Bone union was achieved at the 1-year follow-up CT scans. Physical examination showed a full range of motion in the neck. LESSONS: We reported a case of iatrogenic odontoid distraction that was managed by anterior endoscopically assisted bone grafting. It is a technically feasible and minimally invasive procedure.

Pooled analysis of non-union, re-operation, infection, and approach related complications after anterior odontoid screw fixation.

BACKGROUND: Anterior odontoid screw fixation (AOSF) has been one of the most popular treatments for odontoid fractures. However, the true efficacy of AOSF remains unclear. In this study, we aimed to provide the pooled rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid fractures. METHODS: We searched studies that discussed complications after AOSF for type II or type III odontoid fractures. A proportion meta-analysis was done and potential sources of heterogeneity were explored by meta-regression analysis. RESULTS: Of 972 references initially identified, 63 were eligible for inclusion. 54 studies provided data regarding non-union. The pooled non-union rate was 10% (95% CI: 7%-3%). 48 citations provided re-operation information with a pooled proportion of 5% (95% CI: 3%-7%). Infection was described in 20 studies with an overall rate of 0.2% (95% CI: 0%-1.2%). The main approach related complication is postoperative dysphagia with a pooled rate of 10% (95% CI: 4%-17%). Proportions for the other approach related complications such as postoperative hoarseness (1.2%, 95% CI: 0%-3.7%), esophageal/retropharyngeal injury (0%, 95% CI: 0%-1.1%), wound hematomas (0.2%, 95% CI: 0%-1.8%), and spinal cord injury (0%, 95% CI: 0%-0.2%) were very low. Significant heterogeneities were detected when we combined the rates of non-union, re-operation, and dysphagia. Multivariate meta-regression analysis showed that old age was significantly predictive of non-union. Subgroup comparisons showed significant higher non-union rates in age ≥ 70 than that in age ≤ 40 and in age 40 to <50. Meta-regression analysis did not reveal any examined variables influencing the re-operation rate. Meta-regression analysis showed age had a significant effect on the dysphagia rate. CONCLUSIONS/SIGNIFICANCES: This study summarized the rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid fractures. Elderly patients were more likely to experience non-union and dysphagia.