BACKGROUND: Main objective of this study was to determine whether Hounsfield units (HU) measured in three areas of the axis correlate with successful fusion in patients with type II and shallow type III C2 fractures undergoing anterior odontoid screw osteosynthesis (AOSF). METHODS: Forty-five patients with C2 fractures treated via AOSF were analyzed. Only bony fusion with bone trabeculations across the fracture line was considered a successful result. Preoperative HU values were measured in three zones- corpus, watershed and dens. Statistical analysis was performed to determine significant differences between HU of fused and unfused patients in all three zones of a complete and adjusted patient cohort. RESULTS: Statistically significant differences of HU values were found between fused (corpus- 363.7, watershed- 327.9) and unfused (corpus- 279.5, watershed- 194.2) of the complete cohort and the adjusted cohort. Cut-off HU values in the watershed zone were calculated for the complete (250 and 300) and adjusted cohort (240 and 260), dividing patients into three groups of bone quality. Patients with high watershed bone quality (HU>300) achieved successful fusion in 84.62%, patients with low bone quality (HU<250) in 3.85% and patients with medium bone quality (HU 250-300) in 50%. CONCLUSIONS: Preoperative measurement of HU can be used to predict the probability of successful fusion in patients undergoing AOSF for type II and shallow type III C2 fractures. AOSF is a highly effective treatment modality in patients with watershed HU>300, whereas alternatives should be considered in patients with watershed HU<250.

• MeSH
• dens axis * chirurgie   MeSH
• fraktury páteře * diagnostické zobrazování   chirurgie   MeSH
• kostní šrouby MeSH
• lidé MeSH
• vnitřní fixace fraktury MeSH
• výsledek terapie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE: Separation of C2 growth plates and dens fractures are the most common types of injuries to the axis (C2) in children. Operative treatment of these injuries with the use of direct osteosynthesis requires a profound knowledge of detailed anatomy and dimensions of the axis. The main issue addressed by the study was the age at which the size of the dens is adequate at all levels to accommodate two screws, and the size of the posterior dens angulation angle (PDAA) in a healthy child in individual age periods. METHODS: Dimensions and angles of the dens and C2 in individual age categories in both boys and girls were measured in a series of 203 CT scans of individuals 0-18 years old and on anatomical specimens (42 samples). In addition, 5 histological series of this region from the fetal period were reviewed. RESULTS: Dimensions of the dens gradually increase with age, with a considerable acceleration during growth spurt periods that are different in boys and girls. PDAA is markedly changing with age; in the fetal period, the dens shows a slight anterior angulation which gradually transforms into posterior angulation, as early as between 4 and 6 years of age. The screw insertion angle changes accordingly. CONCLUSION: During growth, there occur changes in PDAA that should be respected in evaluation of transformation of anterior into posterior angulation, as shown by imaging methods. Dens dimensions theoretically allow insertion of two 3.5 mm screws as early as from the age of 1 year.

• Klíčová slova
• Developmental changes, Pediatric C2 anatomy, Posterior dens angulation angle, Screw insertion angle,
• MeSH
• dens axis * diagnostické zobrazování   zranění   chirurgie   MeSH
• dítě MeSH
• fraktury páteře * diagnostické zobrazování   chirurgie   MeSH
• kojenec MeSH
• kostní šrouby MeSH
• lidé MeSH
• mladiství MeSH
• novorozenec MeSH
• předškolní dítě MeSH
• radiografie MeSH
• vnitřní fixace fraktury MeSH
• Check Tag
• dítě MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

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.

• Klíčová slova
• Bone cement, Finite element, Fracture, Odontoid, Spine,
• MeSH
• dens axis * diagnostické zobrazování   zranění   chirurgie   MeSH
• fraktury páteře * diagnostické zobrazování   chirurgie   MeSH
• kostní cementy terapeutické užití   MeSH
• kostní šrouby MeSH
• lidé MeSH
• senioři MeSH
• vnitřní fixace fraktury MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kostní cementy MeSH

PURPOSE: The most common injuries to the upper cervical spine are fractures of the dens axis. Therefore, the purpose of our study was to answer three questions, namely (1) whether the size of the dens is adequate at all levels to accommodate two screws, (2) what the angle of the posterior tilt of the dens is in a healthy individual and (3) compare the measured variables between the sexes. METHODS: The cohort comprised 50 males and 50 females CT examination of the craniocervical junction. We measured the five diameters of the dens and posterior dens angulation angle (PDAA) and screw insertion angle (SIA). The same dimensions were measured in a control group, consisting of 40 non-pathological second cervical vertebrae specimens. RESULTS: On CT scans, the mean PDAA was 162.7 degrees in males and 160.26 degrees in females; the mean SIA was 62.0 degrees in males and 60.2 degrees in females. On specimens, the mean PDAA was 169.47 degrees in males and 166.95 degrees in females; the mean SIA was 65.42 degrees in males and 64.47 degrees in females. All obtained values were higher in males; regardless of their measuring on either CT scans or specimens, differences between males and females were statistically significant (p < 0.05) in a, c, d and e values. CONCLUSIONS: The values of our measurements correlate with the dimensions identified previously in other studies. Based on our clinical experience and measurements, we presume that two 3.5-mm screws can be inserted into the dens of all adult patients, except for those with pronounced anatomical anomalies. Posterior dens angulation angle is slightly larger than we expected. The dens is significantly larger in males almost in all measurement. These slides can be retrieved under Electronic Supplementary Material.

• Klíčová slova
• C2 anatomy, C2 fracture, Dens fracture, Posterior dens angulation angle, Screw insertion angle,
• MeSH
• dens axis * anatomie a histologie   chirurgie   MeSH
• fraktury páteře * patologie   chirurgie   MeSH
• kohortové studie MeSH
• kostní šrouby MeSH
• krční obratle * anatomie a histologie   chirurgie   MeSH
• lidé MeSH
• počítačová rentgenová tomografie MeSH
• vnitřní fixace fraktury MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

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.

• Klíčová slova
• Anterior screw fixation, Biomechanics, Cadaveric study, Cement augmentation, Implant failure, Odontoid process fracture, Osteoporosis,
• MeSH
• biomechanika MeSH
• dens axis zranění   chirurgie   MeSH
• fraktury páteře chirurgie   MeSH
• kostní cementy škodlivé účinky   MeSH
• kostní šrouby škodlivé účinky   MeSH
• lidé MeSH
• mrtvola MeSH
• polymethylmethakrylát škodlivé účinky   MeSH
• selhání protézy škodlivé účinky   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• vnitřní fixace fraktury škodlivé účinky   metody   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• kostní cementy MeSH
• polymethylmethakrylát MeSH

PURPOSE OF THE STUDY In the management of dens axis fractures in patients older than 65 years of age the posterior approach is preferred due to osteoporosis and the risk of a failure of anterior osteosynthesis. The posterior approach, however, is associated with a higher incidence of complications. A combination of anterior transarticular fixation of C1/2 (ATS) with compression osteosynthesis of dens axis significantly increases the stability of osteosynthesis. MATERIAL AND METHODS In the period from 2009 to 2015 our hospital admitted 13 patients older than 65 years of age with a diagnosed type III dens axis fracture based on AO classification. 8 patients sustained a dens axis fracture combined with a stable atlas fracture. The cohort consisted of 13 women aged 67 to 90 years, with the mean age of 82.3 years. None of the female patients were affected neurologically. The dens axis fracture was treated by anterior approach. Once the screw was inserted in the dens axis, two more screws were added, the entrance points of those screws were medial and lateral to the odontoid screw and direction was divergently via C1/2 joints in order to reinforce stability. The patients were monitored at 6-week, 3-, 6- and 12-month follow-ups. Bone healing was confirmed by CT scan. RESULTS No complications were recorded during the surgery in any of the 13 patients. In one female patient the stabilization failed in the early postoperative period. A reoperation from anterior approach with the use of the same method was necessary. In eleven patients bone healing occurred after 6 to 12 months. In two patients pseudoarthrosis was formed with no clinical symptoms. No neurological deterioration or a patient s death was reported in the monitored period within 12 months after the treatment. DISCUSSION Where dens axis fractures in elderly patients are managed operatively, the posterior approach and transarticular fixation of C1/2 with sublaminar loop are preferred. This procedure is considered more reliable, owing to the fears of a failure of osteosynthesis by anterior approach. The most frequent cause of a failure is the pulling out of the screw through the anterior wall of dens axis base in patients with osteoporosis. Concurrently, the anterior approach is regarded as more considerate. The ATS fixation increases stability compared to isolated compression osteosynthesis, which makes it possible to manage the dens axis fractures by a more considerate anterior approach. CONCLUSIONS The ATS is a method that increases stability of compression osteosynthesis in managing dens axis in elderly patients. Key words: dens axis, upper cervical spine fracture, elderly, triple screw technique, anterior transarticular C1/2 stabilization.

• MeSH
• dens axis zranění   MeSH
• fraktury páteře chirurgie   MeSH
• hojení ran MeSH
• kostní šrouby MeSH
• krční obratle chirurgie   MeSH
• lidé MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• vnitřní fixace fraktury přístrojové vybavení   MeSH
• výsledek terapie MeSH
• Check Tag
• lidé MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE OF THE STUDY The aim of the experiment was to compare the bending stiffness of an intact odontoid process with bending stiffness after its simulated type II fracture was fixed with a single lag screw. The experiment was done with a desire to answer the question of whether a single osteosynthetic screw is sufficient for good fixation of a type II odontoid fracture. MATERIAL AND METHODS The C2 vertebrae of six cadavers were used. With simultaneous measurement of odontoid bending stiffness, the occurrence of a fracture (type IIA, Grauer's modification of the Anderson- D'Alonzo classification) was simulated using action exerted by a tearing machine in the direction perpendicular to the odontoid axis. Each odontoid fracture was subsequently treated by direct osteosynthesis with a single lag screw inserted in the axial direction by a standard surgical procedure in order to provide conditions similar to those achieved by routine surgical management. The treated odontoid process was subsequently subjected to the same tearing machine loading as applied to it at the start of the experiment. The bending stiffness measured was then compared with that found before the fracture occurred. The results were statistically evaluated by the t-test for paired samples at the level of significance α = 0.05. RESULTS The average value of bending stiffness for odontoid processes of intact vertebrae at the moment of fracture occurrence was 318.3 N/mm. After single axial lag screw fixation of the fracture, the average bending stiffness for the odontoid processes treated was 331.3 N/mm. DISCUSSION Higher values of bending stiffness after screw fixation were found in all specimens and, in comparison with the values recorded before simulated fractures, the increase was statistically significant. CONCLUSIONS The results of our measurements suggest that the single lag screw fixation of a type IIA odontoid fracture will provide better stability for the fracture fragment-C2 body complex on antero-posterior perpendicular loading than can be found in intact C2 vertebrae. Key words: odontoid fracture, odontoid fixation, bending stiffness, lag screw.

• MeSH
• biomechanika fyziologie   MeSH
• dens axis zranění   chirurgie   MeSH
• fraktury páteře patofyziologie   chirurgie   MeSH
• kostní šrouby * MeSH
• lidé středního věku MeSH
• lidé MeSH
• mrtvola MeSH
• senioři MeSH
• vnitřní fixace fraktury přístrojové vybavení   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

The authors describe their experience with treatment of two neurologically intact male patients, aged 70 and 74 years, presenting with combined lateral atlanto-axial dislocation and odontoid type II fracture. The mechanism of these two craniovertebral junction injuries had been lateroflexion of the neck. The initial attempt at closed reduction using axial traction failed. The authors succeeded with a closed reduction maneuver under general anaesthesia in the first patient in whom long-term stability was achieved by transarticular C2-C1 fixation, together with interlaminar fusion. In the second patient, closed reduction was unsuccessful due to intra-articular soft tissue interposition. Release and reduction were achieved by instrumentation of C1 lateral masses and transpedicular anchorage of screws into the C2. The subsequent Harms C1-C2 stabilisation proved to be effective both in achieving long-term stability and segmental fusion of lateral masses. Aspects of biomechanics as well as a review of pertinent literature are presented.

• MeSH
• atlantoaxiální kloub zranění   MeSH
• dens axis zranění   MeSH
• dislokace kloubu komplikace   chirurgie   MeSH
• fraktury páteře chirurgie   MeSH
• lidé MeSH
• senioři MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

Odontoid process fractures in patients with ankylosing spondylitis (AS) are rare and their finding together with subaxial cervical spine injury is a great exception. Neither the mechanism of such a combined cervical spine injury nor its surgical treatment has so far been reported in the relevant literature (MEDLINE). The authors present two such cases, one in a 30- and the other in a 74-year-old man. Both AS patients showed a common mechanism of injury sustained in a car accident, which involved hitting a solid barrier at 60 to 70 kilometres per hour, resulting in hyperextension of the cervical spine. In both patients the fractures were stabilised from the anterior approach: the dens fractures with one or two screws by the Magerl-Böhler method and the subaxial fractures with long-plate and screw fixation. At 2 post-operative years complete bone union of the subaxial spine was recorded in both patients; complete healing of the dens fracture was achieved in one patient while in the other partial fibrous union of the dens fracture occurred.

• MeSH
• ankylózující spondylitida komplikace   MeSH
• dens axis zranění   MeSH
• dospělí MeSH
• fraktury páteře komplikace   chirurgie   MeSH
• krční obratle zranění   MeSH
• lidé MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• kazuistiky MeSH

We describe the case of an 80-year-old female patient who had undergone anterior C1-C2 transarticular stabilisation and was subsequently treated by the triple-screw method for failed compression osteosynthesis of a AO type III dens axis fracture. Key words: dens axis, upper cervical spine fracture, eldery, triple screw technique, anterior transarticular C1-C2 stabilisation.

• MeSH
• dens axis zranění   chirurgie   MeSH
• fraktury páteře chirurgie   MeSH
• kostní šrouby MeSH
• krční obratle chirurgie   MeSH
• lidé MeSH
• neúspěšná terapie MeSH
• senioři nad 80 let MeSH
• úrazy pádem MeSH
• vnitřní fixace fraktury * MeSH
• Check Tag
• lidé MeSH
• senioři nad 80 let MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH