Abstract:BackgroundRecently, biplanar fluoroscopy is used to evaluate the cervical kinematics, especially to locate the instant center of rotation (ICR) during in vivo motion. This study aims to ascertain the ICR at each cervical segment in the sagittal plane during dynamic motion and assess the differences from previous studies.MethodsWhile three healthy subjects were performing full flexion-extension, two oblique views aligned horizontally and angled at approximately 55° were obtained by biplanar fluoroscopy. The min… Show more
“…In general, extension TD fractures of the cervical spine are caused by hyperextension based on injury mechanism by Allen's classification 1 , 2 , 3 , 4 , 7 , 8 , 9 and occur more commonly at C 2 or C 3 . Hyperextension injury is the component of force most likely to cause anterior TD fracture of C 2 19 , 20 , 21 .…”
Section: Discussionmentioning
confidence: 99%
“…Tear drop fractures of the C 2 axis differ in several ways from TD fractures in the lower cervical spine. In general, TD fractures of the cervical spine are classified into extension TD fractures caused by hyperextension and flexion TD fractures caused by flexion‐compression force based on injury mechanism by Allen's classification of lower cervical spine injury 1 , 2 , 3 , 4 , 7 , 8 , 9 . Flexion TD fractures commonly occur at the C 4 –C 7 vertebra and extension TD fractures occur more commonly at C 2 or C 3 .…”
Objective:To analyze characteristics of surgically managed tear drop (TD) fractures of the C 2 axis associated with other injuries such as hangman's fracture and C 2-3 discoligamentous injury as well as treatment outcomes.Methods: A total of 14 patients (eight men and six women) with TD fractures of the C 2 , who were surgically treated at four national trauma centers of tertiary university hospitals from January 2000 to December 2017, were included in this retrospective study. The mean age of the patients was 45.5 years (ranging from 19 to 74 years). The characteristics, surgical treatment methods (anterior fusion vs posterior fusion), and results of 14 TD fractures of the C 2 were analyzed retrospectively. And the clinical relevance between C 2 TD fracture and hangman's fracture and C 2-3 discoligamentous injury was investigated through the co-occurrence between injuries. The mean follow-up time after surgery was 22.6 months (ranging from 12 to 60 months).Results: Among 14 patients with TD fracture of the C 2 , four patients (28.6%) had anterior TD fracture and 10 patients (71.4%) had posterior TD fracture. All 10 posterior TD fracture patients had anterior C 2-3 displacement. While two of four anterior TD fracture patients had posterior C 2-3 displacement, the remaining two did not. All 14 patients of TD fracture had at least two or more other associated C 2 injuries as well as C 2-3 discoligamentous injuries. About 92.9% (13/14) of the patients had typical or atypical hangman's fracture; 100% (10/10) of the posterior TD fracture patients had hangman's fracture, but 75% (3/4) of the anterior TD fracture had hangman's fracture. At admission, 13 patients were neurologically intact. However, the remaining patient had spinal cord injury with American Spinal Injury Association (ASIA) impairment scale B with C 2-3 bilateral facet dislocation. All four anterior TD fracture patients underwent posterior C 2-3 fusion. While four of 10 posterior TD fracture patients underwent C 2-3 anterior fusion, the remaining six underwent posterior fusion. At last follow-up, 100% (14/14) of the patients achieved solid fusion, and visual analog scale for neck pain was significantly improved (5.9 vs 2.2, P < 0.001). One patient with ASIA impairment scale B had significantly improved to scale D. No major complications occurred.
Conclusion:Our study showed that surgically managed TD fractures of the C 2 showed a high incidence of other associated spine injuries including hangman's fracture and C 2-3 discoligamentous injury. Therefore, special attention and careful radiologic evaluation are needed to investigate the presence of other associated spine injuries including hangman's fracture and C 2-3 discoligamentous injury, which are likely to require surgery.
“…In general, extension TD fractures of the cervical spine are caused by hyperextension based on injury mechanism by Allen's classification 1 , 2 , 3 , 4 , 7 , 8 , 9 and occur more commonly at C 2 or C 3 . Hyperextension injury is the component of force most likely to cause anterior TD fracture of C 2 19 , 20 , 21 .…”
Section: Discussionmentioning
confidence: 99%
“…Tear drop fractures of the C 2 axis differ in several ways from TD fractures in the lower cervical spine. In general, TD fractures of the cervical spine are classified into extension TD fractures caused by hyperextension and flexion TD fractures caused by flexion‐compression force based on injury mechanism by Allen's classification of lower cervical spine injury 1 , 2 , 3 , 4 , 7 , 8 , 9 . Flexion TD fractures commonly occur at the C 4 –C 7 vertebra and extension TD fractures occur more commonly at C 2 or C 3 .…”
Objective:To analyze characteristics of surgically managed tear drop (TD) fractures of the C 2 axis associated with other injuries such as hangman's fracture and C 2-3 discoligamentous injury as well as treatment outcomes.Methods: A total of 14 patients (eight men and six women) with TD fractures of the C 2 , who were surgically treated at four national trauma centers of tertiary university hospitals from January 2000 to December 2017, were included in this retrospective study. The mean age of the patients was 45.5 years (ranging from 19 to 74 years). The characteristics, surgical treatment methods (anterior fusion vs posterior fusion), and results of 14 TD fractures of the C 2 were analyzed retrospectively. And the clinical relevance between C 2 TD fracture and hangman's fracture and C 2-3 discoligamentous injury was investigated through the co-occurrence between injuries. The mean follow-up time after surgery was 22.6 months (ranging from 12 to 60 months).Results: Among 14 patients with TD fracture of the C 2 , four patients (28.6%) had anterior TD fracture and 10 patients (71.4%) had posterior TD fracture. All 10 posterior TD fracture patients had anterior C 2-3 displacement. While two of four anterior TD fracture patients had posterior C 2-3 displacement, the remaining two did not. All 14 patients of TD fracture had at least two or more other associated C 2 injuries as well as C 2-3 discoligamentous injuries. About 92.9% (13/14) of the patients had typical or atypical hangman's fracture; 100% (10/10) of the posterior TD fracture patients had hangman's fracture, but 75% (3/4) of the anterior TD fracture had hangman's fracture. At admission, 13 patients were neurologically intact. However, the remaining patient had spinal cord injury with American Spinal Injury Association (ASIA) impairment scale B with C 2-3 bilateral facet dislocation. All four anterior TD fracture patients underwent posterior C 2-3 fusion. While four of 10 posterior TD fracture patients underwent C 2-3 anterior fusion, the remaining six underwent posterior fusion. At last follow-up, 100% (14/14) of the patients achieved solid fusion, and visual analog scale for neck pain was significantly improved (5.9 vs 2.2, P < 0.001). One patient with ASIA impairment scale B had significantly improved to scale D. No major complications occurred.
Conclusion:Our study showed that surgically managed TD fractures of the C 2 showed a high incidence of other associated spine injuries including hangman's fracture and C 2-3 discoligamentous injury. Therefore, special attention and careful radiologic evaluation are needed to investigate the presence of other associated spine injuries including hangman's fracture and C 2-3 discoligamentous injury, which are likely to require surgery.
“…2 , 81 Some studies narrow this investigation down to the anteroposterior (AP) direction, 88 while others provide a circular estimate of possible distribution areas of ICR in the sagittal plane at each level in the course of in vivo movements. 42 Figure 5 Center of rotation as observed in studies involving healthy participants and providing data eligible for inclusion in a figure. …”
Section: Healthy Conditionsmentioning
confidence: 99%
“…Studies published before 2012 1 , 15 , 22 , 71 were based on radiographs taken between the initial and final position of the studied movements, while studies published later employed a combination of computed tomography (CT) or magnetic resonance imaging (MRI) with biplanar radiography or (video)fluoroscopy. 2 , 42 , 58 , 81 , 88 The former predominantly report a stationary ICR location at each cervical segment, which derives from the average of measurements collected from static full-flexion and extension radiographs and from radiographs collected during slow sagittal movement. 14 The techniques used by the latter group of studies provide a more accurate account about motion of the ICR during the dynamic flexion–extension cycle and identify bone location and three-dimensional orientation with sub-millimeter accuracy.…”
Section: Healthy Conditionsmentioning
confidence: 99%
“… 1 The COR gradually moved anteriorly from C2–C3 to C6–C7 1 , 22 and superiorly in all subaxial segments apart from C5–C6. 42 The antero-posterior (AP) change decreased per degree of flexion–extension, 2 , 42 , 88 although it appears that the position of the CORs is more posteriorly inclined in left–right-left (LRL) rotation than in flexion – extension. 88 …”
Knowledge of spinal kinematics is essential for the diagnosis and management of spinal diseases. Distinguishing between physiological and pathological motion patterns can help diagnose these diseases, plan surgical interventions and improve relevant tools and software. During the last decades, numerous studies based on diverse methodologies attempted to elucidate spinal mobility in different planes of motion. The authors aimed to summarize and compare the evidence about cervical spine kinematics under healthy and degenerative conditions. This includes an illustrated description of the spectrum of physiological cervical spine kinematics, followed by a comparable presentation of kinematics of the degenerative cervical spine. Data was obtained through a systematic MEDLINE search including studies on angular/translational segmental motion contribution, range of motion, coupling and center of rotation. As far as the degenerative conditions are concerned, kinematic data regarding disc degeneration and spondylolisthesis were available. Although the majority of the studies identified repeating motion patterns for most motion planes, discrepancies associated with limited sample sizes and different imaging techniques and/or spine configurations, were noted. Among healthy/asymptomatic individuals, flexion extension (FE) and lateral bending (LB) are mainly facilitated by the subaxial cervical spine. C4–C5 and C5–C6 were the major FE contributors in the reported studies, exceeding the motion contribution of sub-adjacent segments. Axial rotation (AR) greatly depends on C1–C2. FE range of motion (ROM) is distributed between the atlantoaxial and subaxial segments, while AR ROM stems mainly from the former and LB ROM from the latter. In coupled motion rotation is quantitatively predominant over translation. Motion migrates caudally from C1–C2 and the center of rotation (COR) translocates anteriorly and superiorly for each successive subaxial segment. In degenerative settings, concurrent or subsequent lesions render the association between diseases and mobility alterations challenging. The affected segments seem to maintain translational and angular motion in early and moderate degeneration. However, the progression of degeneration restrains mobility, which seems to be maintained or compensated by adjacent non-affected segments. While the kinematics of the healthy cervical spine have been addressed by multiple studies, the entire nosological and kinematic spectrum of cervical spine degeneration is partially addressed. Large—scale in vivo studies can complement the existing evidence, cover the gaps and pave the way to technological and clinical breakthroughs.
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