Avoiding pitfalls in anterior screw fixation for Type II odontoid fractures

Surgeon Experience Is the Most Important Predictor of Case Failure Rate for Anterior Odontoid Screw Fixation: A Large Database Study

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

Determine risk factors and failure rate of anterior odontoid screw fixation surgery.

SUMMARY OF BACKGROUND DATA

Anterior odontoid screw fixation (AOSF) stabilizes type II dens fractures while preserving cervical motion. Despite having potential advantages, AOSF's failure rate and factors contributing to failure remain unknown.

MATERIALS AND METHODS

We identified AOSF patients in the national claims database Pearldiver using CPT code 22318. Failure was defined as the requirement of supplementary posterior fusion surgery in the C1-C2 or occiput-C2 region after the AOSF. We considered potential predictors of failure including age, sex, Charlson Comorbidity Index (CCI), surgeon experience, history of osteoporosis, obesity, and tobacco use. Univariate comparison analysis and logistic regression were conducted to identify factors associated with the need for additional posterior surgery.

RESULTS

For 2008 identified cases of AOSF, 249 cases (12.4%) required additional posterior fusion. Seventy-one of the 249 cases (28.5%) underwent revision surgery on the same day as the AOSF. Over 86% of revisions (215 cases) occurred within 200 days of the initial procedure. Posterior fusion rates are inversely correlated with surgeon experience, with the most experienced surgeons having a rate of 10.0%, followed by 11.5% for moderately experienced surgeons, and 15.0% for the least experienced surgeons. When comparing moderate and inexperienced surgeons to experienced surgeons, the odds ratios for posterior fusion were 1.18 ( P >0.05) and 1.61 ( P <0.006), respectively. Logistic regression revealed that both lesser experience (odds ratio=1.50) and osteoporosis (odds ratio=1.44) were the only factors significantly associated with failure ( P <0.05).

CONCLUSIONS

Our findings indicate a correlation between AOSF success and surgeon experience. While currently published results suggest higher success rates, most of this data originates from experienced surgeons and specialized centers, therefore, they may not accurately reflect the failure rate encountered in a more general practice setting.

LEVEL OF EVIDENCE

Level III.

Neuronavigated Retropharyngeal Anterior Screw Fixation of the Odontoid for the Treatment of C2 Type II Fractures: Case Report

Odontoid fractures, frequently observed in patients over the age of 70, often involve the base of the axis (Anderson-D'Alonzo type 2). For surgical treatment, posterior C1-C2 fixation is the traditional method, whose fusion rates range between 93 and 100%. However, morbidity and mortality rates are high. In addition, cervical motion, especially axial rotation, is postoperatively reduced. Nakanishi and Bohler introduced the anterior screw fixation approach for the surgical treatment of odontoid fracture type II. This procedure preserves the atlantoaxial complex motion, provides immediate stability and high fracture healing rates, and, most importantly, has a low incidence of complications with good fusion rates. The surgical strategy must take into account the patient's anatomy, the morphological characteristics of the fracture, the quality of the bone, and any concomitant injuries. In this chapter, we describe a C2 type II fracture treated via a neuronavigated anterior retropharyngeal approach.

Management of fresh odontoid fractures using posterior C1-2 fixation without fusion: a long-term clinical follow-up study

OBJECTIVE

Posterior C1-2 fixation without fusion makes it possible to restore atlantoaxial motion after removing the implant, and it has been used as an alternative technique for odontoid fractures; however, the long-term efficacy of this technique remains uncertain. The purpose of the present study was to explore the long-term follow-up outcomes of patients with odontoid fractures who underwent posterior C1-2 fixation without fusion.

METHODS

A retrospective study was performed on 62 patients with type II/III fresh odontoid fractures who underwent posterior C1-2 fixation without fusion and were followed up for more than 5 years. The patients were divided into group A (23 patients with implant removal) and group B (39 patients without implant removal) based on whether they underwent a second surgery to remove the implant. The clinical outcomes were recorded and compared between the two groups. In group A, the range of motion (ROM) of C1-2 was calculated, and correlation analysis was performed to explore the factors that influence the ROM of C1-2.

RESULTS

A solid fracture fusion was found in all patients. At the final follow-up, no significant difference was found in visual analog scale score or American Spinal Injury Association Impairment Scale score between the two groups (p > 0.05), but patients in group A had a lower Neck Disability Index score and milder neck stiffness than did patients in group B (p < 0.05). In group A, 87.0% (20/23) of the patients had atlantoodontoid joint osteoarthritis at the final follow-up. In group A, the C1-2 ROM in rotation was 6.1° ± 4.5° at the final follow-up, whereas the C1-2 ROM in flexion-extension was 1.8° ± 1.2°. A negative correlation was found between the C1-2 ROM in rotation and the severity of tissue injury in the atlantoaxial region (r = -0.403, p = 0.024) and the degeneration of the atlantoodontoid joint (r = -0.586, p = 0.001).

CONCLUSIONS

Posterior C1-2 fixation without fusion can be used effectively for the management of fresh odontoid fractures. The removal of the implant can further improve the clinical efficacy, but satisfactory atlantoaxial motion cannot be maintained for a long time after implant removal. A surgeon should reconsider the contribution of posterior C1-2 fixation without fusion and secondary implant removal in preserving atlantoaxial mobility for patients with fresh odontoid fractures.

Short-term posterior C1-C2 pedicle screw fixation without fusion to treat type II odontoid fracture among people under 60 years

INTRODUCTION

Posterior C1-C2 pedicle screw fixation is a reliable technique used in treatment of type II odontoid fracture. However, the loss of cervical range of rotation motion (RORM) was inevitable. There were few studies focusing on the influence of short-term C1-C2 fixation with nonfusion technique to preserve cervical function in patients younger than 60 years. The purpose of this study was to compare cervical RORM which was measured by an improved goniometer, and the clinical outcomes between short-term and long-term C1-C2 fixation techniques in the treatment of Grauer type 2B and 2C odontoid fracture.

MATERIALS AND METHODS

This study represents a retrospective analysis, including patients who underwent primary C1-C2 fixation surgery. These patients were divided into short-term and long-term groups based on whether underwent a fixation removal operation. The clinical results were collected and compared between the two groups. Independent T test and Chi-square analyses were used to identify significant differences between the two groups and dependent T test was used within each group. Statistical significance was set at p < .05.

RESULTS

There were no severe postoperative complications, and all 60 patients achieved spinal stabilization after primary surgery. The mean rotation angle in the short-term group at last follow-up time was 138.39 ± 21.06°, which was better than 83.59 ± 13.06° in the long-term group (p < .05). The same statistical difference was observed in flexion-extension angle, which was 71.11 ± 18.73° in short-term group and 53.34 ± 18.23° in long-term group. The mean NDI score in short-term group at last follow-up time was 1.23 ± 0.86 and better than 8.24 ± 3.17 in long-term group. However, the VAS score in short-term group was 1.82 ± 0.54 which was worse compared to 0.64 ± 0.29 in long-term group.

CONCLUSIONS

The results demonstrated that primary C1-C2 fixation with nonfusion technique could support satisfactory clinical effects. In addition, the removal of instruments after bony fusion could improve the function of cervical movement significantly in patients under 60 years.

Anterior Odontoid Screw Fixation for C2 Fractures: Surgical Nuances, Complications, and Factors Affecting Fracture Union

OBJECTIVE

Type II odontoid fractures are the commonest C2 fractures. The management of dens fractures remains controversial with various radiological and fracture morphological factors affecting the approach and outcomes.

METHODS

All cases of anterior odontoid screw fixation between 2010 and 2020 were retrospectively analyzed. Patients' clinical, radiological (type of fracture, orientation, displacement, and diastasis), operative (single vs. double screw) and follow-up records were documented. The postoperative imaging findings were classified into grades I (excellent), II (good), and III (poor) based on the anatomical alignment with the screw. Follow-up cervical computed tomography was reviewed for fracture union.

RESULTS

A total of 49 patients with a mean age of 37.3 ± 13.8 years were included in the study. The average time from injury to surgery was 23.1 ± 22.2 days. The bicortical screw purchase and superoposterior odontoid tip breach significantly affected the postoperative alignment (P = 0.035 each). Fracture union was noted in 41 (83.7%) patients. The horizontal fracture displacement ≥2.5 mm (P = 0.02) and poor postoperative fracture alignment (P < 0.001) resulted in worse fracture union rates. Transient dysphagia was the commonest complication (n = 12), whereas screw breakout (n = 2) and pullout (n = 2) were other hardware-related complications. One patient underwent re-exploration for screw readjustment and 2 underwent posterior instrumentation.

CONCLUSIONS

Anterior odontoid screw fixation is technically straightforward, less morbid, and preserves biomechanical cervical mobility, when compared with the posterior instrumentation. With careful patient selection, meticulous surgical planning, and intraoperative image-guided screw insertion, good fracture union outcomes can be obtained. In the current study, we were able to achieve stable fracture union in 83.7% patients.

The role of single odontoid screw fixation in treatment of odontoid fracture type II

Background

Odontoid fractures are the most common cervical fractures specially type II. Anterior odontoid screw fixation has many advantages with low incidence of surgical complications.

Purpose

To evaluate the role of single odontoid screw fixation in surgical treatment of odontoid fracture type II.

Study design

A retrospective clinical case series.

Patients and methods

Twelve patients with acute traumatic odontoid fracture type II were surgically treated by anterior single odontoid screw fixation. The visual analogue scale (VAS) and neck disability index (NDI) were used to evaluate the functional outcome among our patients. Plain radiography and CT cervical spine were done in all cases preoperatively and during our period of follow-up (6 months). Preoperative MRI cervical spine was done in all cases.

Results

The study included 12 patients, four of them (33.3%) were females, and 8 (66.7%) were males with a mean age of 41.7 ± 11.4 years. All patients had acute traumatic odontoid fracture type II, oblique fractures in 10 (83.3%) cases, and transverse fractures in 2 (16.7%) cases. All cases operated for anterior single odontoid screw fixation. During our period of follow-up, VAS and neck disability index were improved in all cases. There were 5 cases (41.7%) with transient dysphagia. Solid fusion was achieved in all cases except in one patient (8.3%) (fibrous union).

Conclusion

Single odontoid screw fixation is useful and safe procedure in surgical treatment of odontoid fractures type II. Careful attention to the technical aspects of the procedure and selection of patients are essential for good outcome.

Placement of a single anterior odontoid screw for type II odontoid fractures in a setting with limited resources

Background

Treatment of odontoid fractures with odontoid screws is an established method for fusion. However, it is facilitated by using advanced equipment in the operating theatre not always available as in developing countries.

Objectives

In this study we aim to outline the important key points for successful placement of odontoid screw in the absence of advanced tools, e.g. navigation or O-arm.

Materials and methods

Fifteen patients suffering from type II odontoid fractures were managed with single odontoid screw. Reduction of the fractures was achieved. A simple instrument set was used with the help of a single plane image intensifier. Longitudinal incision was used in 4 cases, and transverse incision was used in the remaining eleven cases. Anatomical identification of the midline helped to mark the entry point. The entry point used was millimetres below the anteroinferior edge of the axis vertebra. A short-headed screw was used.

Results

Road traffic accident was the only mechanism of trauma reported in our study. All of the patients were neurologically intact. All of the patients remained neurologically intact after the procedure. There were no instances of wrong trajectory of the screw in our study. During follow-up, we found good union of all the fractures. Only 2 cases suffered from mild dysphagia.

Conclusion

Fixation of odontoid fractures by anterior odontoid screws appears to be a safe and feasible procedure even in underequipped theatres. Anatomical knowledge helps in determining midline. Various modifications can help in overcoming shortcomings.

Postoperative intracranial migration of a C2 odontoid screw: A case report and literature review

Background:

Intracranial migration of odontoid screws is a rare but serious complication of anterior odontoid screw fixation not often reported in literature by neurosurgeons. Here, we describe the second case in literature of intracranial migration of an odontoid screw.

Case Description:

A 64-year-old neurologically intact patient with a type II odontoid fracture secondary to trauma underwent anterior odontoid screw fixation without any intraoperative complications. He tolerated the procedure well, and postoperative imaging demonstrated near anatomic correction of the fracture with satisfactory placement of the lag screw. Unfortunately, the patient was subsequently lost to follow up and he presented 7 months later for a routine outpatient computed tomography (CT) of the cervical spine, which demonstrated upward migration of the screw into the intracranial cavity abutting the medulla, with CT angiography of the neck also confirming the screw lying between the two vertebral arteries. Magnetic resonance imaging of the cervical spine also demonstrated the odontoid screw lying within close proximity to the ventral cervicomedullary junction, marginating the left vertebral artery. Subsequently, the patient was managed with removal of the odontoid screw and posterior cervical arthrodesis and instrumented fusion.

Conclusion:

Our case demonstrates the rare but serious complication of intracranial odontoid screw migration, which we bring to the attention of the neurosurgical community. The recognition of risk factors for this complication and optimized management of this rare occurrence is important for surgeons to recognize.

The Healing Rate of Type II Odontoid Fractures Treated With Posterior Atlantoaxial Screw-rod Fixation: A Retrospective Review of 77 Patients

BACKGROUND

In theory, temporary posterior atlantoaxial screw-rod fixation for type II odontoid fractures is a way to preserve rotatory motion. However, the healing rate of type II odontoid fractures treated in this way is unknown; that is, the risk associated with conducting a temporary screw-rod fixation for type II odontoid fractures is unknown. This study investigates the healing rate of type II odontoid fractures treated with posterior atlantoaxial screw-rod fixation by CT imaging and evaluates the feasibility of conducting a temporary screw-rod fixation for type II odontoid fractures.

METHODS

Patients with type II odontoid fracture who underwent posterior atlantoaxial screw-rod fixation in our spine center from January 2011 to December 2014 were identified. Patients older than 65 years or younger than 18 years were excluded. Those who were confirmed to have healing odontoid fractures on CT imaging were included. Those in whom fracture healing was not confirmed were asked to undergo a CT examination. Fracture healing was confirmed on the basis of the presence of bridging bone across the odontoid fracture site on CT imaging.

RESULTS

Seventy-seven patients (56 men and 21 women) were included in the study. The average age of the patients was 40.7 ± 11.6 years (range, 18 to 64 years). The mean duration of follow-up was 26.4 ± 4.6 months (range, 24 to 40 months). Fracture healing was observed in 73 patients (94.8%).

DISCUSSION

The healing rate of type II odontoid fractures (with an age range of 18 to 64 years) treated with modern posterior atlantoaxial fixation is relatively high. For patients at that age range, posterior atlantoaxial temporary screw-rod fixation for type II odontoid fractures can be conducted with a low risk of nonunion.

LEVEL OF EVIDENCE

Level IV, therapeutic.

Balloon kyphoplasty and additional anterior odontoid screw fixation for treatment of unstable osteolytic lesions of the vertebral body C2: a case series

Background

Unstable osteolytic lesions of the occipitocervical junction are rare and may occur in hematological malignancy or vertebral hemangioma, among others. Different case reports have been published about vertebroplasty for treatment of spinal metastases of the upper cervical spine. Only few cases concern balloon kyphoplasty of C2. We present a consecutive case series including four patients with an osteolytic lesion of the dens axis and describe a technical note for balloon kyphoplasty of C2 and an additional anterior odontoid screw fixation.

Methods

Four consecutive patients with an osteolytic lesion of the vertebral body of C2 were treated by anterior balloon kyphoplasty and additional anterior odontoid screw fixation of the dens axis. The radiological imaging showed a lytic process of the vertebral body C2 with no vertebral collapse but involvement of more than 50% of the vertebral body in all patients.

Results

Two cases of potentially unstable osteolytic lesions of C2 by myeloma, one case with metastatic osteolytic lesion of C2 by adenocarcinoma of the colon and one patient with vertebral hemangioma located in C2 were presented to our clinic. In all cases, surgical treatment with an anterior balloon kyphoplasty of C2 and an additional anterior, bicortical odontoid screw placement was performed. Control x-rays showed sufficient osteosynthesis and cement placement in the vertebral body C2.

Discussion

Anterior balloon kyphoplasty and anterior odontoid screw placement is a safe treatment option for large osteolytic lesions of C2. The additional odontoid screw placement has the advantage of providing more stabilization and may prevent late complications, like odontoid fractures. For patients with potentially unstable or large osteolytic lesions of the dens without spinal cord compression or neurological symptoms we recommend the placement of an anterior odontoid screw when performing a balloon kyphoplasty. Level of evidence: - IV: retrospective or historical series.

The comparison of clinical outcome of fresh type II odontoid fracture treatment between anterior cannulated screws fixation and posterior instrumentation of C1-2 without fusion: a retrospective cohort study

Background

Recently, the excellent outcomes of temporary fixation of C1-2 without fusion in the treatment of odontoid fracture had been reported. It is still unclear if this technique could achieve the equivalent outcomes as the golden standard technique of anterior screw fixation. The objective of this study is to compare the clinical outcome of two treatments of fresh type II odontoid fracture: anterior cannulated screws fixation (ACSF) versus posterior instrumentation of C1-2 without fusion (PIWF).

Methods

This is a retrospective study. This series included 28 males and 8 females, and the mean age was 41.5 years (range, 22 to 70 years). Eleven patients were treated with ACSF, and 25 patients with PIWF. For PIWF, the implants were removed after fracture union was confirmed at 0.75~1.5 years later. All patients underwent preoperative and serial postoperative clinical examinations at approximately 3 months, 6 months, and annually thereafter. The neck disability index (NDI) was used to assess the neck discomfort caused by the operation. The range of rotary motion was evaluated at each visit. All fractures were reassessed postoperatively with serial X-films and CT scans of the cervical spine at each follow-up visit, to evaluate screw position, fracture alignment, and fusion status.

Results

All patients achieved immediate spinal stabilization after surgery, and none experienced neurologic deterioration. The follow-up periods ranged from 24 to 60 months. The average range of neck rotation was dramatically lost in PIWF after fixation (46° and 89° respectively in ACSF and PIWF), and recovered to 83° after the implant was removed. The NDI in PIWF was statistically higher than that in ACSF (5 and 13% respectively in ACSF and PIWF) after the first operation and decreased to 8% 1 year after the secondary operation. The fusion rates were 90.9 and 96% respectively in ACSF and PIWF. Both groups had a case of fracture non-union.

Conclusions

For fresh type II odontoid fractures, high rate of fracture union can be achieved by both ACSF and PIWF. For most fresh type II odontoid fractures, anterior screw fixation was the best option for its simplicity and preservation of normal atlanto-axial rotary function. Posterior instrumentation without fusion could preserve most of the atlanto-axial rotary function and lead to moderate neck discomfort and is also a good alternative if anterior screw fixation is contraindicated.

Percutaneous anterior C1/2 transarticular screw fixation: salvage of failed percutaneous odontoid screw fixation for odontoid fracture

BACKGROUND

The objective of this study is to investigate the outcomes and safety of using percutaneous anterior C1/2 transarticular screw fixation as a salvage technique for odontoid fracture if percutaneous odontoid screw fixation fails.

METHODS

Fifteen in 108 odontoid fracture patients (planned to be treated by percutaneous anterior odontoid screw fixation) were failed to introduce satisfactory odontoid screw trajectory. To salvage this problem, we chose the percutaneous anterior C1/2 transarticular screw fixation technique in treatment of these patients. The visual analogue score (VAS) of neck pain and Neck Disability Index (NDI) of all patients were scored at pre-operation, 3 months after operation, and final follow-up. Additional, technique-related complications were recorded and collected.

RESULTS

Percutaneous C1/2 transarticular screw fixation was performed successfully in all 15 patients whose odontoid screw fixation failed. No technique-related complications (such as nerve injury, spinal cord injury, and esophageal injury) occurred. The VAS of neck pain and NDI score improved significantly (P = 0.000) after operation, and no significant differences were found when compared to 93 non-salvage patients who successfully performed the percutaneous anterior odontoid screw fixation. No screw loose or breakage occurred, all of the odontoid fractures achieve radiographic fusion, bony fusion bridge could be observed at the C1/2 lateral articular facet on 9/15 patients.

CONCLUSIONS

We suggest that percutaneous anterior C1/2 transarticular screw fixation is a good alternative salvage technique if percutaneous odontoid screw fixation failed, and it is a minimally invasive, feasible, and safe technique.

The Corona Dentis: Description of an Anatomic Variant with Technical Implications for Anterior Odontoid Screw Placement

BACKGROUND

Type 2 odontoid fractures are the most common cervical fractures among the elderly. Neurologic deficit is usually caused by myelopathy as a result of posterior dens migration. Direct anterior screw placement provides stabilization and can preserve C1-C2 movement. The presence of a bony excrescence on the anterior superior tip of the dens may lead to placement of a screw of incorrect length.

METHODS

Twenty C2 dry specimens were examined for the presence of a corona dentis, which is a bony excrescence in the coronal plane near the apex of the dens. When identified, measurements of the corona dentis were performed using calipers and a ruler. In addition, anteroposterior (AP) and lateral fluoroscopy was performed on all specimens found to have a corona dentis.

RESULTS

A corona dentis was found on 20% of our C2 specimens and had an average width of 9 mm and an average height of 4.5 mm. The average width of the dens did not vary as the normal tip of the dens transitioned into the coronae. In no specimen did the corona dentis seem to be composed of trabecular bone and it was seen as a superior projection of cortical bone on fluoroscopy. On fluoroscopy, the corona dentis could be identified on a true AP projection. In angulated AP views, fluoroscopic images overestimated the length of the corona dentis.

CONCLUSIONS

We describe a new entity termed the corona dentis because of its crownlike feature. It is a superior cortical bone protrusion and should be noted as a variant of the dens during anterior odontoid screw placement. Its propensity to increase the height of the dens markedly can lead to higher rates of neurologic deficits during type 2 odontoid fractures if not appreciated. A true AP view is critical for correct screw size placement.

Advantages of Direct Insertion of a Straight Probe Without a Guide Tube During Anterior Odontoid Screw Fixation of Odontoid Fractures

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The aim of this study was to compare the anterior odontoid screw fixation (AOSF) with a guide tube or with a straight probe.

SUMMARY OF BACKGROUND DATA

AOSF associates with several complications, including malpositioning, fixation loss, and screw breakage. Screw pull-out from the C2 body is the most common complication.

METHODS

All consecutive patients with type II or rostral shallow type III odontoid fractures who underwent AOSFs during the study period were enrolled retrospectively. The guide-tube AOSF method followed the standard published method except C3 body and C2-3 disc annulus rimming was omitted to prevent disc injury; instead, the guide tube was anchored at the anterior inferior C2 vertebra corner. After 2 screw pull-outs, the guide-tube cohort was analyzed to identify the cause of instrument failure. Thereafter, the straight-probe method was developed. A guide tube was not used. A small pilot hole was made on the most anterior side of the inferior endplate, followed by insertion of a 2.5 mm straight probe through the C2 body. Non-union and instrument failure rates and screw-direction angles of the guide-tube and straight-probe groups were recorded.

RESULTS

The guide-tube group (n = 13) had 2 screw pull-outs and 1 non-union. The straight-probe group (n = 8) had no complications and significantly larger screw-direction angles than the guide-tube group (60.5 ± 4.63 vs. 54.8 ± 3.82 degrees; P = 0.047).

CONCLUSION

Straight-probe AOSF yielded larger direction angles without injuring bone and disc. Complications were absent. The procedure was easier than guide-tube AOSF and assured sufficient engagement, even in horizontal fracture orientation cases.

LEVEL OF EVIDENCE

3.

Posterior reduction and temporary fixation for odontoid fracture: a salvage maneuver to anterior screw fixation

STUDY DESIGN

A prospective study.

OBJECTIVE

To evaluate the outcomes of posterior reduction and temporary fixation using the C1-C2 screw-rod system for odontoid fracture unsuitable for anterior screw fixation.

SUMMARY OF BACKGROUND DATA

Anterior screw fixation has become the most widely used surgical procedure for the stabilization of odontoid fractures. However, if there is any contraindication for anterior fixation, posterior atlantoaxial fusion is preferred, eliminating the normal rotation of the atlantoaxial complex.

METHODS

A consecutive series of 22 patients with odontoid fracture unsuitable for anterior screw fixation were involved in this study. Posterior reduction and fixation without fusion using the C1-C2 screw-rod system was performed. Once fracture healing was obtained, instrumentation was removed. The visual analogue scale of neck pain, neck stiffness, American Spinal Injury Association impairment scale, patient satisfaction, and neck disability index were recorded. The range of motion of C1-C2 in flexion-extension and rotation was calculated.

RESULTS

The average age at internal fixation surgery was 40.2±11.3 years. The mean duration of follow-up was 41.8±26.8 months. There were no complications associated with instrumentation. All patients returned to their preoperative work. Fracture healing was observed in 21 patients and the instrumentation was removed. After removing the instrumentation, the visual analogue scale was reduced and neck stiffness were relieved (all P<0.01). Patient satisfaction and neck disability index had improved (all P<0.01). The range of motion of C1-C2 returned to 4.75°±1.62° and 25.70°±5.51° in flexion-extension and in rotation, respectively. No osteoarthritis was observed at the C1-C2 lateral mass joints.

CONCLUSION

Posterior reduction and temporary fixation using the C1-C2 screw-rod system was an optimal salvage maneuver to anterior screw fixation for odontoid fracture. It could effectively avoid the motion loss of C1-C2 caused by posterior atlantoaxial fusion.

LEVEL OF EVIDENCE

3.

Avoiding early complications and reoperation during occipitocervical fusion in pediatric patients

OBJECT

Surgical arthrodesis for pediatric occipitocervical (OC) instability has a high rate of success in a wide variety of challenging circumstances; however, identifying potential risk factors can help to target variables that should be the focus of improvement. The aim of this paper was to examine risk factors predictive of failure in a population of patients who underwent instrumented OC arthrodesis using a uniform surgical philosophy.

METHODS

The authors conducted a retrospective cohort study of pediatric patients who underwent OC fusion from 2001 to 2013 at a single institution to determine risk factors for surgical failure, defined as reoperation for revision of the arthrodesis or instrumentation. The primary study outcome was either radiographic confirmation of successful OC fusion or surgical failure requiring revision of the arthrodesis or instrumentation. The secondary outcome was the underlying cause of failure (hardware failure, graft failure, or infection). Univariate analysis was performed to assess the association between outcome and patient demographics, cause of OC instability, type of OC instrumentation, bone graft material, biological adjuncts, and complications.

RESULTS

Of the 127 procedures included, 20 (15.7%) involved some form of surgical failure and required revision surgery. Univariate analysis revealed that patients with deep wound infections requiring debridement were more likely to require surgical revision of the hardware or graft (p = 0.002). Subgroup analysis revealed that patients with skeletal dysplasia or congenital spinal anomalies were more likely to develop hardware failure than patients with other causes of OC instability (p = 0.020). Surgical failure was not associated with the method of C-2 fixation, type of rigid OC instrumentation, bone graft material, use of bone morphogenetic protein or biological adjuncts, cause of instability, sex, age, or having previous OC fusion operations.

CONCLUSIONS

Pediatric patients in the present cohort with postoperative wound infections requiring surgical debridement had higher surgical failure rates after OC fusion. Those with skeletal dysplasia and congenital spinal anomalies were more likely to require reoperation for hardware failure. Better understanding of the mode of surgical failure may enable surgeons to develop strategies to decrease the need for reoperation in pediatric patients with OC instability.

Cement-augmented anterior screw fixation of Type II odontoid fractures in elderly patients with osteoporosis

BACKGROUND CONTEXT

Closed reduction and internal fixation by an anterior approach is an established option for operative treatment of displaced Type II odontoid fractures. In elderly patients, however, inadequate screw purchase in osteoporotic bone can result in severe procedure-related complications.

PURPOSE

To improve the stability of odontoid fracture screw fixation in the elderly using a new technique that includes injection of polymethylmethacrylat (PMMA) cement into the C2 body.

STUDY DESIGN

Retrospective review of hospital and outpatient records as well as radiographs of elderly patients treated in a university hospital department of orthopedic surgery.

PATIENT SAMPLE

Twenty-four elderly patients (8 males and 16 females; mean age, 81 years; range, 62-98 years) with Type II fractures of the dens.

OUTCOME MEASURES

Complications, cement leakage (symptomatic/asymptomatic), operation time, loss of reduction, pseudarthrosis and revision surgery, patient complaints, return to normal activities, and signs of neurologic complications were all documented.

METHODS

After closed reduction and anterior approach to the inferior border of C2, a guide wire is advanced to the tip of the odontoid under biplanar fluoroscopic control. Before the insertion of one cannulated, self-drilling, short thread screws, a 12 gauge Yamshidi cannula is inserted from anterior and 1 to 3 mL of high-viscosity PMMA cement is injected into the anteroinferior portion of the C2 body. During polymerization of the cement, the screws are further inserted using a lag-screw compression technique. The cervical spine then is immobilized with a soft collar for 8 weeks postoperatively.

RESULTS

Anatomical reduction of the dens was achieved in all 24 patients. Mean operative time was 64 minutes (40-90 minutes). Early loss of reduction occurred in three patients, but revision surgery was indicated in only one patient 2 days after primary surgery. One patient died within the first eight postoperative weeks, one within 3 months after surgery. In five patients, asymptomatic cement leakage was observed (into the C1-C2 joint in three patients, into the fracture in two). Conventional radiologic follow-up at 2 and 6 months confirmed anatomical healing in 16 of the 19 patients with complete follow-up. In two patients, the fractures healed in slight dorsal angulation; one patient developed a asymptomatic pseudarthrosis. All patients were able to resume their pretrauma level of activity.

CONCLUSIONS

Cement augmentation of the screw in Type II odontoid fractures in elderly patients is technically feasible in a clinical setting with a low complication rate. This technique may improve screw purchase, especially in the osteoporotic C2 body.