Current concepts in the treatment of Anderson Type II odontoid fractures in the elderly in Germany, Austria and Switzerland

Comparison of intraoperative CT- and cone beam CT-based spinal navigation for the treatment of atlantoaxial instability

BACKGROUND CONTEXT

Due to the complexity of neurovascular structures in the atlantoaxial region, spinal navigation for posterior C1-C2 instrumentation is nowadays a helpful tool to increase accuracy of surgery and safety of patients. Many available intraoperative navigation devices have proven their reliability in this part of the spine. Two main imaging techniques are used: intraoperative CT (iCT) and cone beam computed tomography (CBCT).

PURPOSE

Comparison of iCT- and CBCT-based technologies for navigated posterior instrumentation in C1-C2 instability.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

A total of 81 consecutive patients from July 2014 to April 2020.

OUTCOME MEASURES

Screw accuracy and operating time.

METHODS

Patients with C1-C2 instability received posterior instrumentation using C2 pedicle screws, C1 lateral mass or pedicle screws. All screws were inserted using intraoperative imaging either using iCT or CBCT systems and spinal navigation with autoregistration technology. Following navigated screw insertion, a second intraoperative scan was performed to assess the accuracy of screw placement. Accuracy was defined as the percentage of correctly placed screws or with minor cortical breach (<2 mm) as graded by an independent observer compared to misplaced screws.

RESULTS

A total of 81 patients with C1-C2 instability were retrospectively analyzed. Of these, 34 patients were operated with the use of iCT and 47 with CBCT. No significant demographic difference was found between groups. In the iCT group, 97.7% of the C1-C2 screws were correctly inserted; 2.3% showed a minor cortical breach (<2 mm); no misplacement (>2 mm). In the CBCT group, 98.9% of screws were correctly inserted; no minor pedicle breach; 1.1% showed misplacement >2 mm. Accuracy of screw placement demonstrated no significant difference between groups. Both technologies allowed sufficient identification of screw misplacement intraoperatively leading to two screw revisions in the iCT and three in the CBCT group. Median time of surgery was significantly shorter using CBCT technology (166.5 minutes [iCT] vs 122 minutes [CBCT]; p<.01).

CONCLUSIONS

Spinal navigation using either iCT- or CBCT-based systems with autoregistration allows safe and reliable screw placement and intraoperative assessment of screw positioning. Using the herein presented procedural protocols, CBCT systems allow shorter operating time.

MFI-11 Predicts Post-Operative Serious Complications in Patients Undergoing Surgery for Odontoid Fractures

STUDY DESIGN

Retrospective Cohort.

OBJECTIVES

The objective of this study was to analyze postoperative complications in different mFI-11 groups after surgery for odontoid fractures in a geriatric population.

METHODS

A single center retrospective review of odontoid fractures surgery (between 2013 and 2022) in patients aged 65 years and older was conducted. The primary outcome was the occurrence of a major complication (Calvien-Dindo ≥4) within 30 days post-surgery. The secondary outcome was the occurrence of a major complication within 3 months after surgery, and death within 1-month post-surgery. Survival curve, multi-variate analysis was performed and adjusted receiver operating characteristic curves were generated.

RESULTS

There were 92 patients included in this study, with a mean age of 80.5 years. Serious complication occurred for 16 patients (17%) during hospitalization. Multivariate analysis demonstrated an mFI 11 >.27 was strongly and independently associated with serious complications within 1-month post-surgery (OR = 16.7, 95% CI = 4.50-83), as well as serious complications within 3 months post-surgery (OR = 11.8, 95% CI = 3.48-49.1) and death within 1 month post-surgery (OR = 11.7; 95% CI = 3.02-60.4). The Receiver Operator Characteristics (ROC) curves for the three models all have an Area Under the Curve (AUC) value greater than 0.7.

CONCLUSIONS

The mFI-11 is a straightforward and validated tool that can be used during the preoperative period to identify the patient's level of frailty and assess their risk of postoperative complications. Patients with mFI-11 ≥.27 are at greater risk of serious complications within 1 and 3 months' post-surgery and death within 1 month post-surgery.

Development and first application testing of a new protocol for CT-based stability evaluation of the injured upper cervical spine

PURPOSE

For trauma surgeons, the evaluation of the stability of the upper cervical spine may be demanding. The aim of this study was to develop a protocol for decision-making on upper cervical spine stability in trauma patients based on established parameters obtained by CT imaging as well as testing the protocol by having it applied by trauma surgeons.

METHODS

A structured literature search on upper cervical spine stability was performed. The best evaluated instability criteria in CT imaging were determined. Based on these parameters a protocol for stability evaluation of the injured upper cervical spine was developed. A first application testing was performed. In addition to the assessment of instability, the time required for the assessment was analyzed.

RESULTS

A protocol for CT-based stability evaluation of the injured upper cervical spine based on the current literature was developed and displayed in a flow chart. Testing of the protocol found the stability of the cervical spine was correctly assessed in 55 of 56 evaluations (98.2%). In one test run, a stable upper cervical spine was judged to be unstable. Further analysis showed that this case was based on a measurement error. The assessment time of CT-images decreased significantly during repeat application of the protocol (p < 0.0001), from 336 ± 108 s (first case) to 180 ± 30 s (fourth case).

CONCLUSION

The protocol can be applied quickly and safely by non-specialized trauma surgeons. Thus, the protocol can support the decision-making process in CT-based evaluation of the stability of the injured upper cervical spine.

A biomechanical comparison of a cement-augmented odontoid screw with a posterior-instrumented fusion in geriatric patients with an odontoid fracture type IIb

PURPOSE

Possible surgical therapies for odontoid fracture type IIb include odontoid screw osteosynthesis (OG) with preservation of mobility or dorsal C1/2 fusion with restriction of cervical rotation. In order to reduce material loosening in odontoid screw osteosynthesis in patients with low bone density, augmentation at the base of the axis using bone cement has been established as a suitable alternative. In this study, we compared cement-augmented OG and C1/2 fusion according to Harms (HG).

METHODS

Body donor preparations of the 1st and 2nd cervical vertebrae were randomized in 2 groups (OG vs. HG). The range of motion (ROM) was determined in 3 principle motion plains. Subsequently, a cyclic loading test was performed. The decrease in height of the specimen and the double amplitude height were determined as absolute values as an indication of screw loosening. Afterward, the ROM was determined again and loosening of the screws was measured in a computed tomography.

RESULTS

A total of 16 were included. Two groups of 8 specimens (OG vs. HG) from patients with a median age of 80 (interquartile range (IQ) 73.5-85) years and a reduced bone density of 87.2 (IQ 71.2-104.5) mg/cc dipotassium hydrogen phosphate were examined for their biomechanical properties. Before and after exposure, the OG preparations were significantly more mobile. At the time of loading, the OG had similar loading properties to HG decrease in height of the specimen and the double amplitude height. Computed tomography revealed similar outcomes with regard to the screw loosening rate (62.5 vs. 87.5%, p = 0.586).

CONCLUSION

In patients with an odontoid fracture type IIb and reduced bone density, cement-augmented odontoid screw yielded similar properties in the loading tests compared to the HG. It may, therefore, be considered as a primary alternative to preserve cervical mobility in these patients.

PICA injury secondary to anterior odontoid screw fixation: Case report of an exceptional complication

BACKGROUND

Odontoid fracture is a common injury in the upper cervical spine that can sometimes be managed by anterior odontoid screw fixation.

CASE DESCRIPTION

We report the first case of iatrogenic postero-inferior cerebellar artery (PICA) injury while performing anterior odontoid screw fixation for a type II odontoid fracture in a 22-year-old man. Fisher grade 4 subarachnoid hemorrhage secondary to iatrogenic pseudoaneurysm formation was managed by the endovascular neuroradiologist. Odontoid fracture was then managed posteriorly using Harm's technique. Postoperative 12-month follow-up revealed good clinical and radiological results. CT scan showed fusion. Complete exclusion of the pseudo aneurysm with a mild stroke in the inferior left cerebellar hemisphere were noted on the MRI. There were no cerebellar ataxia or swallowing disorders.

CONCLUSION

To the best of our knowledge, this is the first case report of iatrogenic PICA injury in anterior odontoid screw fixation. The patient was well managed in our institution within a multidisciplinary team. We recommend that surgical management of odontoid fractures should be performed in expert centres.

Odontoid screw placement for Anderson type II odontoid fractures: how do duration from injury to surgery and clinical and radiological factors influence the union rate? A multicenter retrospective study

OBJECTIVE

Anderson type II odontoid fractures are severe conditions, mostly affecting elderly people (≥ 70 years old). Surgery can be performed as a primary treatment or in cases of failed conservative management. This study aimed to investigate how duration from injury to surgery, as well as clinical, radiological, and surgical risk factors, may influence the union rate after anterior odontoid screw placement for Anderson type II odontoid fractures.

METHODS

The authors conducted a retrospective multicenter study. Demographic, clinical, surgical, and radiological data of patients who underwent anterior odontoid screw placement for Anderson type II fractures were retrieved from institutional databases. Study exclusion criteria were prolonged corticosteroid drug therapy (> 4 weeks), polytraumatic injuries, oncological diagnosis, and prior cervical spine trauma.

RESULTS

Eighty-five patients were included in the present investigation. The union rate was 76.5%, and 73 patients (85.9%) did not report residual instability. Age ≥ 70 years (p < 0.001, OR 6), female gender (p = 0.016, OR 3.61), osteoporosis (p = 0.009, OR 4.02), diabetes (p = 0.056, OR 3.35), fracture diastasis > 1 mm (p < 0.001, OR 8.5), and duration from injury to surgery > 7 days (p = 0.002, OR 48) independently influenced union rate, whereas smoking status (p = 0.677, OR 1.24) and odontoid process angulation > 10° (p = 0.885, OR 0.92) did not.

CONCLUSIONS

Although many factors have been reported as influencing the union rate after anterior odontoid screw placement for Anderson type II fractures, duration from injury to surgery > 7 days appears to be the most relevant, resulting in a 48 times higher risk for nonunion. Early surgery appears to be associated with better radiological outcomes, as reported by orthopedic surgeons in other districts. Prospective comparative clinical trials are needed to confirm these results.

Cement augmentation of odontoid peg fractures: the effect of cement volume and distribution on construct stiffness

PURPOSE

The cement augmentation of a conventional anterior screw fixation in type II odontoid process fractures for elderly patients significantly increased stiffness and load to failure under anterior-posterior load in comparison with non-augmented fixation. The amount and quality of bone cement are usually taken ad hoc in clinical practise. In this study, we wanted to clarify the role of bone cement amount and its quality to the stiffness of odontoid and vertebrae body junction.

METHODS

Finite-element method was used to achieve different scenarios of cement augmentation. For all models, an initial stiffness was calculated. Model (1) the intact vertebrae were virtually potted into a polymethylmethacrylate base via the posterior vertebral arches. A V-shaped punch was used for loading the odontoid in an anterior-posterior direction. (2) The odontoid fracture type IIa (Anderson-D'Alonzo classification) was achieved by virtual transverse osteotomy. Anterior screw fixation was virtually performed by putting self-drilling titanium alloy 3.5 mm diameter anterior cannulated lag screw with a 12 mm thread into the inspected vertebrae. A V-shaped punch was used for loading the odontoid in an anterior-posterior direction. The vertebrae body was assumed to be non-cemented and cemented with different volume.

RESULTS

The mean cement volume was lowest for body base filling with 0.47 ± 0.03 ml. The standard body filling corresponds to 0.95 ± 0.15 ml. The largest volume corresponds to 1.62 ± 0.12 ml in the presence of cement leakage. The initial stiffness of the intact C2 vertebrae was taken as the reference value. The mean initial stiffness for non-porous cement (E = 3000 MPa) increased linearly (R2 = 0.98). The lowest stiffness (123.3 ± 5.8 N/mm) was measured in the intact C2 vertebrae. However, the highest stiffness (165.2 ± 5.2 N/mm) was measured when cement leakage out of the odontoid peg occurred. The mean initial stiffness of the base-only cemented group was 147.2 ± 8.4 N/mm compared with 157.9 ± 6.6 N/mm for the base and body cemented group. This difference was statistically significant (p < 0.0061). The mean initial stiffness for porous cement (E = 500 MPa) remains constant. Therefore, there is no difference between cemented and non-cemented junction. This difference was not statistically significant (p < 0.18).

CONCLUSION

The present study showed that the low porous cement was able to significantly influence the stiffness of the augmented odontoid screw fixation in vitro, although further in vivo clinical studies should be undertaken. Our results suggest that only a small amount of non-porous cement is needed to restore stiffness at least to its pre-fracture level and this can be achieved with the injection of 0.7-1.2 ml of cement. These slides can be retrieved under Electronic Supplementary Material.

Functional Outcome of Elderly Patients Treated for Odontoid Fracture: A Multicenter Study

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVE

Analysis of impact of conservative and surgical treatments on functional outcome of geriatric odontoid fractures.

SUMMARY OF BACKGROUND DATA

Treatment of odontoid fractures in aged population is still debatable.

METHODS

One hundred fourty-seven consecutive odontoid fractures in elderly patients were classified according to Anderson-D'Alonzo and Roy-Camille classifications. Philadelphia type collar was always positioned and kept as a treatment whenever acceptable. Halo-vest, anterior screw fixation, C1-C2 posterior arthrodesis, and occipito-cervical fixation were the other treatments adopted. Conservative or surgical treatment strategy was more significantly influenced by antero-posterior displacement (< or >5 mm) and by surgeon decision. On admission ASA, modified Rankin scale (mRS-pre) and Charlson Comorbidity Index (CCI) were assessed. Modified Rankin scale (mRS-post), Neck Disability Index (NDI), and Smiley Webster Pain Scale (SWPS) were administered 12 to 15 months after treatment to estimate functional outcome in terms of general disability, neck-related disability, and ability to return to work/former activity. Risk of treatment crossover was calculated considering factors affecting outcome. Fracture healing process in terms of fusion-stability, no fusion-stability, no fusion-no stability was evaluated at 12 months through a cervical computed tomography (CT) scan. Dynamic cervical spine x-rays were obtained whether necessary. No fusion-stability was considered an adequate treatment goal in our geriatric population. Chi square/Fisher exact test and logistic regression were performed for statistical anal.

RESULTS

Overall 67 patients were treated conservatively whereas 80 underwent surgery. Collar was adopted in 45 patients, while anterior odontoid fixation and C1-C2 posterior arthrodesis were preferred for 30 patients each. 79.8% of patients showed good outcomes according to NDI. No significant differences were observed between patients of 65 to 79 years and more than or equal to 80 years (P = 0.81). CCI greatly correlated with mRS-post, with higher indexes in 68.8% of cases characterized by good outcomes (P = 0.05). mRS-pre correlated with NDI (P < 0.000001) and mRS-post (P = 0.04). CCI, mRS-pre, and surgery were associated with worse NDI, while both C1-C2 posterior arthrodesis and occipito-cervical stabilization were associated with worse mRS-post, respectively in 40% and 30% of cases. Younger patients had a higher risk of treatment crossover.

CONCLUSION

mRS-pre and CCI provided two independent predictive values respectively for functional outcome and post-treatment disability. Compared with conservative immobilizations, surgery revealed no advantages in the elderly in terms of functional outcome.

LEVEL OF EVIDENCE

3.

Surgical treatment of type II odontoid fractures in elderly patients: a comparison of anterior odontoid screw fixation and posterior atlantoaxial fusion using the Magerl-Gallie technique

PURPOSE

This single-centre retrospective study compared anterior odontoid screw fixation and posterior atlantoaxial fusion in the surgical treatment of type II B odontoid fractures according to Grauer in elderly patients.

METHODS

Between 1994 and 2014, 133 consecutive patients above 60 years presenting with type II B odontoid fracture were treated surgically in our department. They were divided retrospectively into two groups. Group A included 47 patients in whom anterior odontoid screw fixation was performed. Group B with 86 patients underwent posterior atlantoaxial fusion. The clinical and radiological data were analysed. Any reoperation during the follow-up was recorded and evaluated.

RESULTS

The mean age in group A (74.19 years) was significantly less than in group B (78.16 years). The mean operative time in group A (64.5 min) was significantly shorter than in group B (116 min). Again, the mean amount of blood loss in group A (79 ml) was significantly less than in group B (379 ml). The mean postoperative hospital stay was significantly shorter in group A (17.4 days) than in group B (30 days). The mean follow-up was 29.3 months in group A and 32 months in group B. The rate of pseudoarthrosis was significantly higher in group A (25.5%) than in group B (3.5%). Furthermore, the need for revision surgery was significantly increased in group A (23.4%) than in group B (10.47%).

CONCLUSIONS

Odontoid screw fixation is a less invasive surgery for type II B odontoid fractures in elderly patients. However, posterior atlantoaxial fusion provides a superior surgical outcome regarding fracture healing and the need for surgical revisions. These slides can be retrieved under Electronic Supplementary Material.

Biomechanical comparison of cemented versus non-cemented anterior screw fixation in type II odontoid fractures in the elderly: a cadaveric study

BACKGROUND CONTEXT

Odontoid process fractures are the most common injuries of the cervical spine in the elderly. Anterior screw stabilization of type II odontoid process fractures improves survival and function in these patients but may be complicated by failure of fixation.

PURPOSE

The present study aimed to determine whether cement augmentation of a standard anterior screw provides biomechanically superior fixation of type II odontoid fractures in comparison with a non-cemented standard screw.

STUDY DESIGN

Twenty human cadaveric C2 vertebrae from elderly donors (mean age 83 years) were obtained.

METHODS

Anderson and D'Alonzo type IIa odontoid fracture was created by transverse osteotomy, and fluoroscopy-guided anterior screw fixation was performed. The specimens were divided into two matched groups. The cemented group (n=10) had radiopaque high viscosity polymethylmethacrylate cement injected via Jamshidi needle into the base of the odontoid process. The other group was not augmented. A V-shaped punch was used for loading the odontoid in an anteroposterior direction until failure. The failure state was defined as screw cutout or 5% force decrease. Mean failure load and bending stiffness were calculated.

RESULTS

The mean failure load for the cemented group was 352±12 N compared with 168±23 N for the non-cemented group (p<.001). The mean initial stiffness of the non-cemented group was 153±19 N/mm compared with 195±29 N/mm for the cemented group (p<.001) CONCLUSIONS: Cement augmentation of an anterior standard screw fixation of type II odontoid process fractures in elderly patients significantly increased load to failure under anteroposterior load in comparison with non-augmented fixation. This may be a valuable technique to reduce failure of fixation.

Odontoid Fracture in Patients Age >75 Years Surgically Managed by the Harms Technique: Bone Healing and 1-Year Mortality Rate in 57 Cases

BACKGROUND

Odontoid fracture is the most common lesion of the cervical spine in persons age >70 years. Management of these fractures has become a public health issue. In this study, we evaluated bone fusion, early complications, and mortality in a cohort of patients age >75 years who underwent surgical management of odontoid fracture using the Harms technique.

METHODS

This study is a retrospective analysis of 57 patients treated surgically between 2002 and 2016 in a single spine surgery institution. Age at diagnosis, comorbidities, and American Society of Anesthesiologists (ASA) score were analyzed. At a 6-month follow-up, bone healing was evaluated with computed tomography scans.

RESULTS

The mean patient age was 85.5 ± 6.6 years, and 53% of the patients had an ASA score ≥3. According to the Anderson classification, 70% of the patients had a type 2 odontoid fracture. The average duration of follow-up was 15.7 months. Ten patients were lost to follow-up. The rate of early complications was 19%, with no mechanical complications reported. At a 6-month follow-up, a solid bony union was seen in all patients. The 1-year mortality was 14%.

CONCLUSIONS

Surgical management of odontoid fractures in elderly patients using the Harms technique is associated with an excellent rate of bone healing with acceptable rates of early complications and mortality.

Trends in the surgical management of odontoid fractures in patients above 75 years of age: Retrospective study of 70 cases

BACKGROUND

Odontoid fractures are the most common upper cervical spine fracture in adults over 70 years of age. Hence, treatment of these fractures has public health implications.

OBJECTIVES

Evaluate the early complications, bone healing and mortality in patients above 75 years of age who undergo surgical treatment of an odontoid fracture. Compare the results between patients operated with the Harms technique or anterior screw fixation.

METHODS

This was a retrospective study of 70 patients with an odontoid fracture who were treated surgically between 2000 and 2015 at the Hôpital de la Timone in France. The age at the time of diagnosis, comorbidities, ASA score and autonomy were evaluated. Bone healing was determined using computed tomography.

RESULTS

In the cohort, 22 patients underwent anterior screw fixation, 38 were treated using the Harms technique and 10 with other procedures. The average age was 85.1 years. Fifty-four percent of patients had an ASA score above 3. The average follow-up was 23.4 months. An Anderson type II fracture was present in 80.6% of patients. In the anterior screw fixation group, the operative time was significantly shorter than in the Harms group and no blood transfusions were needed. However, 13.6% of these patients had to be re-operated because the initial construct was unstable; no patients in the Harms group underwent revision surgery. There were more complications in the anterior screw fixation group than in the Harms group: 41% versus 13.2% (P<0.02). The fractures had healed in all patients reviewed after 1 year. The 3-month survival in the anterior screw fixation group was 64.7% and it was 81.3% in the Harms group. These rates were stable at 1 year with no statistical differences between groups.

CONCLUSION

Surgical treatment of odontoid fractures in the elderly results in an excellent union rate. The mortality rate is stable after 3 months. In our experience, the Harms technique has a lower risk of complications and better mechanical stability than anterior screw fixation. Despite the steep learning curve, we believe the Harms technique is probably the best choice for treating odontoid fractures in the elderly.

LEVEL OF EVIDENCE

IV.

Spinal navigation for posterior instrumentation of C1-2 instability using a mobile intraoperative CT scanner

OBJECTIVE Spinal navigation techniques for surgical fixation of unstable C1-2 pathologies are challenged by complex osseous and neurovascular anatomy, instability of the pathology, and unreliable preoperative registration techniques. An intraoperative CT scanner with autoregistration of C-1 and C-2 promises sufficient accuracy of spinal navigation without the need for further registration procedures. The aim of this study was to analyze the accuracy and reliability of posterior C1-2 fixation using intraoperative mobile CT scanner-guided navigation. METHODS In the period from July 2014 to February 2016, 10 consecutive patients with instability of C1-2 underwent posterior fixation using C-2 pedicle screws and C-1 lateral mass screws, and 2 patients underwent posterior fixation from C-1 to C-3. Spinal navigation was performed using intraoperative mobile CT. Following navigated screw insertion in C-1 and C-2, intraoperative CT was repeated to check for the accuracy of screw placement. In this study, the accuracy of screw positioning was retrospectively analyzed and graded by an independent observer. RESULTS The authors retrospectively analyzed the records of 10 females and 2 males, with a mean age of 80.7 ± 4.95 years (range 42-90 years). Unstable pathologies, which were verified by fracture dislocation or by flexion/extension radiographs, included 8 Anderson Type II fractures, 1 unstable Anderson Type III fracture, 1 hangman fracture Levine Effendi Ia, 1 complex hangman-Anderson Type III fracture, and 1 destructive rheumatoid arthritis of C1-2. In 4 patients, critical anatomy was observed: high-riding vertebral artery (3 patients) and arthritis-induced partial osseous destruction of the C-1 lateral mass (1 patient). A total of 48 navigated screws were placed. Correct screw positioning was observed in 47 screws (97.9%). Minor pedicle breach was observed in 1 screw (2.1%). No screw displacement occurred (accuracy rate 97.9%). CONCLUSION Spinal navigation using intraoperative mobile CT scanning was reliable and safe for posterior fixation in unstable C1-2 pathologies with high accuracy in this patient series.

Cement augmented anterior odontoid screw fixation is biomechanically advantageous in osteoporotic patients with Anderson Type II fractures

STUDY DESIGN

A biomechanical human cadaveric study.

OBJECTIVE

The authors tested a cannulated and perforated lag screw and compared in situ polymethylmethacrylate (PMMA) augmentation against nonaugmentation for fixation of osteoporotic type II odontoid fractures.

SUMMARY OF BACKGROUND DATA

Osteoporosis has been identified as a strong predictor for pseudarthrosis after screw fixation of type II odontoid fractures with cut-out through the anterior wall of C2 as the most frequent mode of implant failure. The concept of PMMA augmentation of the proximal screw shank could serve as a useful supplement in this context.

METHODS

A total of 18 fresh-frozen human cadaveric C2 vertebrae were harvested (median 86.5 y; range, 69-98 y). Reduced bone quality was verified by quantitative computed tomography. Type II odontoid fractures were created and repaired with a cannulated lag screw, which has perforations in the proximal screw shank. Additional PMMA augmentation was carried out for 9 specimens. The position of the screw and cement distribution were evaluated by computed tomography. Values for maximum force to failure, energy to failure, and stiffness were statistically compared between cement augmented and nonaugmented screws.

RESULTS

Cement distribution in the C2 vertebral body was circumferential around the screw shank without leakage into the spinal canal or into the fracture gap in all 9 specimens. The cement augmented screws showed a 2.4 times higher maximum force to failure (363±94 N, P<0.001), a 2.7 times higher energy to failure (1300±698 mJ, P<0.001), and a 1.76 times higher stiffness (90±35 N/mm, P=0.031) in comparison with the nonaugmented screws.

CONCLUSIONS

Cement augmentation for fixation of osteoporotic type II odontoid fractures showed biomechanical advantages. It was also shown that cement augmentation of the newly developed screw is technically easy and safe under in vitro conditions. The technique might be useful with regard to the surgical treatment of elderly patients with osteoporotic odontoid fractures.

Atlantoaxial instability in acute odontoid fractures is associated with nonunion and mortality

BACKGROUND CONTEXT

Odontoid fractures are the most common geriatric cervical spine fractures. Nonunion rates have been reported to be up to 40% and mortality up to 35%, and poor functional outcomes are common. Atlantoaxial instability (AAI) is a plausible prognostic factor, but its role has not been previously examined.

PURPOSE

To determine the effect of severe AAI on the outcomes of nonunion and mortality in patients with acute odontoid fractures.

STUDY DESIGN

Retrospective cohort/single institution.

PATIENT SAMPLE

One hundred twenty-four consecutive patients with acute odontoid fractures.

OUTCOME MEASURES

Rates of nonunion and mortality.

METHODS

Two independent blinded reviewers measured AAI using postinjury computed tomography scans. Patients were classified as having "severe" or "minimal" AAI on the basis of greater versus less than or equal to 50% mean subluxation across each C1-C2 facet joint. Rates of nonunion and mortality were compared using independent samples t tests and adjusted for age, displacement, and subtype using binary logistic regression.

RESULTS

One hundred seven patients had minimal AAI and 17 had severe AAI. Mean follow-up was 4.4 months (standard deviation=4.6). Patients with severe AAI were more likely to experience nonunion (29% vs. 10%, respectively; p=.03) and mortality (35% vs. 14%, respectively; p=.03) regardless of treatment modality. Fracture displacement correlated with AAI (r(2)=0.65). When adjusted for patient age, the odds ratio of nonunion with severe AAI approached significance at 3.3 (95% confidence interval [CI]: 0.9-11.7). Mortality prediction with AAI approached a twofold increased risk (odds ratio=2.1; 95% CI: 0.6-6.8). In patients with Type-II fractures, the odds of mortality with severe AAI approached a threefold higher risk (odds ratio=3.3; 95% CI: 0.9-12.3).

CONCLUSIONS

Patients with acute odontoid fractures and severe AAI may be more likely to experience nonunion and mortality, suggesting the possibility that aggressive management could be warranted. Further investigation with a large prospective study including patient-important functional outcomes is justified.

Systematic review on surgical and nonsurgical treatment of type II odontoid fractures in the elderly

Odontoid fractures type II according to Anderson and d'Alonzo are not uncommon in the elderly patients. Still, due to the paucity of evidence the published treatment guidelines are far from equivocal. This systematic review focuses on the published results of type II odontoid fracture treatment in the elderly with regard to survival, nonunion, and complications. After a systematic literature research 38 publications were included. A cumulative analysis of 1284 published cases found greater survival if elderly patients with odontoid fractures type II received surgical treatment (RR = 0.64). With regard to nonunion in 669 published cases primary posterior fusion had the best fusion results. The systematic literature review came to the following conclusions. (1) Surgical stabilisation of odontoid fractures type II improves survival in patients between 65 and 85 years of age compared to nonsurgical treatment. (2) Posterior atlantoaxial fusion for odontoid fractures type II in the elderly has the greatest bony union rate. (3) Odontoid nonunion is not associated with worse clinical or functional results in the elderly. (4) The complication rate of nonsurgical treatment is similar to the complication rate of surgical treatment of odontoid fractures type II in the elderly.

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.