Reconstruction after resection of C2 vertebral tumors: A comparative study of 3D-printed vertebral body versus titanium mesh

Background

Surgical resection of C2 vertebral tumors is challenging owing to the complex anatomy of C2 vertebrae and the challenges to surgical exposure. Various surgical approaches are available, but some are associated with excessively high risks of complications. An additional challenge is reconstruction of the upper cervical spine following surgery. In the last decade, additive-manufacturing personalized artificial vertebral bodies (AVBs) have been introduced for the repair of large, irregular bony defects; however, their use and efficacy in upper cervical surgery have not been well addressed. Therefore, in this study, we compared instrumented fixation status between patients who underwent conventional titanium mesh reconstruction and those who underwent the same resection but with personalized AVBs.

Methods

We performed a retrospective comparative study and recruited a single-institution cohort of patients with C2 vertebral tumors. Clinical data and imaging findings were reviewed. Through data processing and comparative analysis, we described and discussed the feasibility and safety of surgical resection and the outcomes of hardware implants. The primary outcome of this study was instrumented fixation status.

Results

The 31 recruited patients were divided into two groups. There were 13 patients in group A who underwent conventional titanium mesh reconstruction and 18 group B patients who underwent personalized AVBs. All patients underwent staged posterior and anterior surgical procedures. In the cohort, 9.7% achieved total en bloc resection of the tumor, while gross total resection was achieved in the remaining 90.3%. The perioperative complication and mortality rates were 45.2% and 6.5%, respectively. The occurrence of perioperative complications was related to the choice of anterior approach (p < 0.05). Group A had a higher complication rate than group B (p < 0.05). Four patients (4/13, 30.8%) developed hardware problems during the follow-up period; however, this rate was marginally higher than that of group B (1/18, 5.6%).

Conclusions

Total resection of C2 vertebral tumors was associated with a high risk of perioperative complications. The staged posterior and retropharyngeal approaches are better surgical strategies for C2 tumors. Personalized AVBs can provide a reliable reconstruction outcome, yet minor pitfalls remain that call for further modification.

C1-C2 Injury: Factors influencing mortality, outcome, and fracture healing

BACKGROUND

C1-C2 injury represents 25-40% of cervical injuries and predominantly occurs in the geriatric population.

METHODS

A prospective multicentre study was conducted under the aegis of the french spine surgery society (SFCR) investigating the impact of age, comorbidities, lesion type, and treatment option on mortality, complications, and fusion rates.

RESULTS

A total of 417 patients were recruited from 11 participating centres. The mean ± SD age was 66.6 ± 22 years, and there were 228 men (55%); 5.4% presented a neurological deficit at initial presentation. The most frequent traumatic lesion was C2 fracture (n = 308). Overall mortality was 8.4%; it was 2.3% among those aged ≤ 60 years, 5.0% 61-80 years, and 16.0% > 80 years (p < 0.001). Regarding complications, 17.8% of patients ≤ 70 years of age presented with ≥ 1 complication versus 32.3% > 70 years (p = 0.0009). The type of fracture did not condition the onset of complications and/or mortality (p > 0.05). The presence of a comorbidity was associated with a risk factor for both death (p = 0.0001) and general complication (p = 0.008). Age and comorbidities were found to be independently associated with death (p < 0.005). The frequency of pseudoarthrosis ranged from 0 to 12.5% up to 70 years of age and then constantly and progressively increased to reach 58.6% after 90 years of age.

CONCLUSIONS

C1-C2 injury represents a serious concern, possibly life-threatening, especially in the elderly. We found a major impact of age and comorbidities on mortality, complications, and pseudarthrosis; injury pattern or treatment option seem to have a minimal effect.

[Spinal navigation for posterior cervical and cervicothoracic instrumentation]

OBJECTIVE

Safe placement of posterior cervical or high-thoracic pedicle screws, transarticular screws C1/2, translaminar screws C2 or cervical lateral mass screws under the guidance of spinal navigation.

INDICATIONS

All posterior cervical and cervicothoracic instrumentation with screws: instabilities and deformities of rheumatoid, traumatic, neoplastic, infectious, iatrogenic or congenital origin; multilevel cervical spinal stenosis with degenerative instability or kyphosis of the affected spinal segment.

CONTRAINDICATIONS

There are no absolute contraindications.

SURGICAL TECHNIQUE

Prone position on a gel mattress, rigid head fixation, e.g., with Mayfield tongs; if appropriate, closed reduction under lateral image intensification; midline posterior surgical approach at the level of the segments to be instrumented; if necessary, open reduction; insertion of the cervical/upper thoracic screws under the guidance of spinal navigation; if necessary, posterior decompression; instrumentation longitudinal rods; if a fusion is to be obtained, decortication of the posterior bone elements with a high-speed burr and onlay of cancellous bone or bone substitutes.

POSTOPERATIVE MANAGEMENT

In stable instrumentation, no postoperative immobilization with cervical collar is necessary. Drain removal on postoperative day 2-3, suture removal on postoperative day 14, clinical and x‑ray control 3 and 12 months after surgery or in case of clinical or neurological deterioration.

RESULTS

Numerous studies showed that the use of spinal navigation reduces implant malplacement rates significantly. Furthermore, it allows a reduction of the radiation dose for the operation team up to 90%.

Trabecular Anatomy of the Axis Vertebra: A Study of Shaded Volume-Rendered Computed Tomography Images

BACKGROUND

To date, trabecular morphology studies have been conducted on thin-section computed tomography (CT) scans of cadaveric bone. Here we describe the trabecular anatomy of the axis vertebra as revealed by an innovative imaging tool.

METHODS

Ten patients who underwent thin-slice CT scans for suspected cervical spine injury were prospectively subjected to shaded volume-rendered 3-dimensional reconstruction of the images. The trabecular anatomy thus depicted was recreated, and the mechanical vectors were deduced independently by a senior radiologist and spine surgeon and then matched. The clinical implications were postulated.

RESULTS

The most striking trabeculae are the vertical compression trabeculae connecting the C1 facet to the C3 body. The center of the body of C2 has a space with sparse trabeculae; similarly, the pars interarticularis also has a clear void. The dens contain predominantly tensile trabeculae that are retained even in older patients. Midline remnants of the odontoid body synchondrosis persist even into late adulthood.

CONCLUSIONS

Shaded volume-rendered imaging appears to be an excellent tool for studying the trabecular anatomy of cancellous bone. The weight-bearing trabeculae run from the C1-2 facet to the C3 body; the inferior facet contributes little to weight-bearing.

Comparison of Cervical Alignment and Clinical Outcomes in Patients with Os Odontoideum versus Non-Os Odontoideum after Atlantoaxial Fixation

OBJECTIVE

The purpose of this study was to compare the effect of atlantoaxial fixation on cervical alignment and clinical outcomes in patients with os odontoideum (OO) versus non-os odontoideum (non-OO).

METHODS

A total of 119 patients who underwent atlantoaxial fixation for instability were identified between January 1998 and January 2014. Inclusion criteria included age more than 21 years and diagnosis of OO and non-OO. There were 22 OO patients, and 20 non-OO patients. Measuring the Oc-C1 Cobb angle, C1-2 Cobb angle, C2-7 Cobb angle, and C2-7 sagittal vertical axis (SVA) was assessed. Clinical outcome was assessment of suboccipital pain was determined using a visual analogue scale (VAS), and Japanese Orthopedic Association (JOA) scores were obtained in all patients pre- and postoperatively.

RESULTS

The preoperative C1-2 angle in the OO group (26.02°±10.53°) was significantly higher than the non-OO group (p=0.04). After C1-2 fixation, the OO group had significantly higher kyphotic change in the C1-2 angle (ΔC1-2) (3.2°±7.3° [OO] vs. -1.46°±7.21° [non-OO]) (p=0.04), and higher decrease in postoperative C2-7 SVA (ΔC2-7 SVA) (5.64±11.56 mm [OO] vs. -0.51± 6.57 mm [non-OO]) (p=0.04). Both groups showed improvements in the health related quality of life (HRQOL) after surgery based on the VAS and JOA score (p<0.001).

CONCLUSION

After fixation, kyphotic angular change in atlantoaxial joint and decrease C2-7 SVA were marked in the OO group. Both the OO and non-OO groups improved in neurological function and outcome after surgery.

Pediatric Hangman's Fracture: A Comprehensive Review

PURPOSE

Over 170 years ago, traumatic spondylolisthesis of the axis or hangman's fracture was described. Most descriptions of this entity have focused on adult presentations.

METHODS

We review the literature on pediatric cases of hangman's fracture emphasizing the embryological as well as presentation aspects.

RESULTS

The majority of cervical spine fractures in children occur at C1 and C2 vertebrae. A normal anterolisthesis of C2 can be seen in younger children and can mimic the anterolisthesis seen after traumatic spondylolisthesis.

CONCLUSIONS

Traumatic spondylolisthesis of the axis in children requires further investigation due to the current emphasis in the literature on adult clinical findings and diagnostic challenges from the developmental immaturity of the pediatric skeleton.