Analysis of clinical efficacy and risk factors of relapse in young patients with cervical instability treated by manipulation / 中国骨伤

OBJECTIVE@#To determine the clinical efficacy of different manipulation in the treatment of cervical instability in young people, and to analyze the risk factors of relapse of cervical instability in young people.@*METHODS@#From March 2021 to June 2022, the clinical data of 120 young patients with cervical instability were retrospectively analyzed. According to the different treatment methods, they were divided into rotation group (60 cases, 3 cases of loss) and tendon group (60 cases, 5 cases of loss). There were 25 males and 32 females in rotation-traction manipulation group;age ranged from 22 to 44 years old with a median of 28 years old;course of disease ranged from 0.17 to 120 months with amedian of 22 months. There were 22 males and 33 females in tendon-regulating manipulation group;age ranged from 21 to 42 years old with a median of 27 years old;course of disease ranged from 0.23 to 180 months with a median of 24 months. Both groups were treated for 2 weeks, once every other day for 7 times, and were followed up for 1 year. The clinical efficacy of the two groups was evaluated, and the visual analogue scale (VAS), neck disability index (NDI) were observed before and after treatment. One year after the course of treatment, patients with effective treatment were followed up to make statistics on recurrence. Patients with recurrence were included in the recurrence group, while those without recurrence were included in the non-recurrence group. Factors that may affect symptom recurrence were analyzed, and univariate and multivariate Logistic regression analysis were performed.@*RESULTS@#The 13 patients who failed the treatment (4 cases in the rotation-traction manipulation group and 9 cases in the tendon-regulating manipulation group) were not followed up. All the 99 patients who were effective in treatment were followed up ranged from 303 to 406 days with a median of 359 days. No complications occurred in all patients. There were significant differences in VAS and NDI between the two groups after treatment and before treatment (P<0.05), and there were significant differences in VAS and NDI between the two groups after treatment (P<0.05). Ninety-nine patients achieved follow-up, 56 (56.57%) relapsed and 43 (43.43%) did not. Univariate correlation analysis showed that NDI index, the time spent at the desk every day, the time spent using electronic products every day and angular displacement of anterior flexion before treatment in the relapse group were significantly higher than those in the non-relapse group (P<0.05). Logistic regression analysis showed that the time spent at the desk every day [OR=2.447, 95%CI(1.255, 4.771)], the time spent using electronic products every day [OR=1.892, 95%CI(1.066, 3.358)] and the angular displacement of anterior flexion of the cervical before treatment [OR=1.246, 95%CI(1.045, 1.485) ]were the risk factors for relapse.@*CONCLUSION@#Both rotation-traction manipulation and tendon-regulating manipulation can effectively treat cervical instability in young people, and rotation-traction manipulation has more advantages than tendon-regulating manipulation in improving cervical pain and cervical dysfunction in patients. The time spent at the desk every day, the time spent using electronic products every day, and the increase of cervical flexion angle displacement will increase the risk of relapse in patients.

Imaging analysis of ossification of the nuchal ligament with cervical curvature and segmental stability / 中国组织工程研究

BACKGROUND: In degenerative cervical spondylosis associated with cervical curvature straightening or segmental instability, ossification of the nuchal ligament caused by chronic injury of the nuchal ligament is very common. OBJECTIVE: To investigate the correlation between ossification of the nuchal ligament and cervical curvature and segmental stability of the cervical spine. METHODS: Data of 109 patients with degenerative cervical spondylosis, who were treated in Department of Spinal Surgery of Affiliated Hospital of Xuzhou Medical University from October 1, 2017 to October 31, 2018, were retrospectively analyzed. There were 61 male patients and 48 female patients, who aged 30 to 81 years old at a mean age of (55. 8±11. 1) years. All patients signed the informed consent. This study was approved by the Ethics Committee of Affiliated Hospital of Xuzhou Medical University. The patients underwent the X-ray examinations of cervical spine. The imaging observation included the distribution and degree of ossification of the nuchal ligament and the change of cervical physiological curvature and segment stability. The patients were divided into ossification group and non-ossification group according to whether or not the patients had ossification of the nuchal ligament. Gender, age, cervical curvature and lower cervical stability were compared between the two groups. Pearson correlation analysis was used to compare the relationship between the degree of ossification of the nuchal ligament and cervical curvature and cervical stability. Binary Logistic regression analysis was applied to evaluate the significant risk factors for the development of ossification of the nuchal ligament. RESULTS AND CONCLUSION: (1) Of 109 patients with degenerative cervical spondylosis, 56 patients with ossification of the nuchal ligament and ossification involved 83 cervical segments in ossification of the nuchal ligament patients, most of which were C4-5 (39. 8%) and Cm (42. 2%). (2) There was significant difference in age, C2-C7 Cobb angle, Jackson physiological stress curve, parameter angular displacement and horizontal displacement between the ossification group and non-ossification group (P < 0. 05). The degree of ossification of the nuchal ligament was positively correlated with angular displacement (f=0. 486, P < 0. 05). (3) The incidence of ossification of the nuchal ligament was significantly higher in patients with lower cervical instability (P < 0. 05). Age and lower cervical instability parameter angular displacement were significant risk factors for the development of ossification of the nuchal ligament. (4) Patients with ossification of the nuchal ligament are more likely to have cervical curvature straightening and lower cervical instability, especially in the segment instability. In the diagnosis and treatment of degenerative cervical spondylosis, the existence of ossification of the nuchal ligament causes corresponding attention.

Establishment and evaluation of a cadaveric model of chronic strain-induced upper cervical spine instability based on fascia-bone theory / 中国组织工程研究

BACKGROUND: Studies regarding the instability of upper cervical spine in cadaveric specimens are mostly based on an acute violence model, and there is still no chronic strain-induced upper cervical instability model. OBJECTIVE: To construct and evaluate the cadaveric model of the upper cervical spine instability caused by chronic strain according to the theory of “fascia and bone.” METHODS: Nine fresh cadaveric cervical spine specimens were prepared and the normal vertebral range of motion was detected by Motion Analysis Motion Capture System. The upper cervical spine instability model was constructed by using BOSE dynamic fatigue testing machine with maximum flexion, extension and rotation fatigue loading. Then, the vertebral range of motion was tested again. The anterior flexion, posterior extension, left flexion, right flexion, left and right rotation of the occipitoatlantoaxial joint, the atlantoaxial joint and the whole upper cervical spine were compared before and after modeling. The implementation of the study protocol complied with the relevant ethical requirements of Southern Medical University, and the specimens were voluntarily donated. RESULTS AND CONCLUSION: (1) During anterior flexion, the range of motion of the atlantoaxial joint (C1-2) and the entire upper cervical vertebra (C0-2) of the specimens after modeling was significantly larger than that before modeling (P 0.05). (3) During right rotation, the range of motion of the whole upper cervical spine (C0-2) of the specimens after modeling was significantly increased compared with that before modeling (P < 0.05). During both left and right rotation, the range of motion of the atlantoaxial joint (C1-2) and the whole upper cervical spine (C0-2) of the specimens was significantly larger than that of the specimens before modeling (P < 0.05). Therefore, this model can be used to reflect the state of upper cervical instability caused by chronic strain.

Progress on clinical application of anterior cervical pedicle screw fixation for instable cervical spine disease / 中国骨伤

Instability of the cervical spine disease requires surgery to restore stability. In the past, surgical methods were divided into two kinds of anterior and posterior. But each has its own disadvantages:anterior vertebral screw has a higher failure rate, sometimes need a second operation; and posterior pedicle screw, lateral mass screw and facet joint screw may make greater trauma, lead to longer hospitalization. For general instable cervical spine disease, according to the location of the disease, only with the anterior or posterior approach can achieve a stable effect. However, it often fails to achieve the desired stability with only anterior or posterior approach for the three column injury of single segment, the disease need for multi-segment corpectomy and discectomy. Meanwhile, combined with the anterior and posterior have more obvious disadvantages:such as prolonged operation time, greater surgical injury, increased risk of infection and so on.In recent years, anterior transpedicular screw (ATPS) as a new technique was used for cervical spine fixation. Its laboratory and clinical studies have been conducted about biomechanical properties, morphological feasibility, pull-out strength, radiological features and new technology for inserting screws. Because of its strong stability, perfect mechanical properties and the satisfactory results of patients, which has been recognized by many scholars. Although this technique has been used in clinical practice, Its long-term clinical effect needs to be further clarified. Even so, the innovative proposal will provide a new thread for the majority of doctors and colleagues in treating unstable cervical disease.

The effects of cervical spinous process fracture with posterior ligamentous complex injury on stability of the goat cervical spine / 医用生物力学

Objective To investigate the effect of cervical spinous process fracture with posterior ligamentous complex (PLC) injury on biomechanical stability of the goat cervical spine specimen in vitro, and evaluate the role of posterior structure in maintaining the stability of cervical spine. Methods Twenty-four fresh goat cervical spine C3-6 specimens were randomly and evenly divided into 3 groups: control group (group A), simple cervical spinous process fracture group (group B) and cervical spinous process fracture with PLC injury group (group C). Under loading of 1.5 N·m torque, the range of motion (ROM) in each group was respectively measured under 6 working conditions: flexion, extension, lateral bending and axial rotation, and the ROM differences among 3 groups were compared by using one-way ANOVA analysis. Results Simple cervical spinous process fracture had little effect on the stability of cervical spine and there was no significant difference in ROM between group B and control group (P>0.05) under all working conditions. Compared with control group, the ROM in flexion, extension and axial rotation significantly increased in group C (P0.05). Conclusions Simple cervical spinous process fracture does not affect the overall stability of cervical spine. Cervical spinous process fracture with PLC injury is more likely to cause cervical instability than simple cervical spinous process fracture, and surgical intervention is required in cervical spinous process fracture with PLC injury.

Instrumentación cervical en pacientes menores de 10 años / Cervical instrumentation and fusion in children under 10 years old

Introducción: la instrumentación de la columna cervical pediátrica ha ganado terreno en la última década. Las diferencias anatómicas y biomecánicas entre la columna cervical pediátrica y del adulto hacen que la cirugía requiera de una minuciosa preparación toda vez que se utilizan implantes diseñados para adultos. El objetivo de este estudio fue evaluar los resultados posoperatorios en una serie de niños <10 años sometidos a fusión cervical instrumentada, y describir la técnica quirúrgica y las complicaciones. Materiales y Métodos: Se evaluó a 28 pacientes con patología cervical tratados con fusión instrumentada utilizando las técnicas descritas por Roy-Camille y Magerl para masas laterales, de Goel-Harms para C1-C2, y las fusiones occipitocervicales con placas occipitales o rótulas. Los criterios de inclusión fueron: pacientes <10 años, cirugía primaria y un seguimiento mínimo de 2 años. Resultados: La muestra incluyó 17 niñas y 11 niños, con un seguimiento promedio de 3.8 años (rango 2-10). La edad promedio fue de 6.1 años (rango 1.6-10). La tasa promedio de complicaciones generales fue del 32,1%. Los pacientes que tuvieron más complicaciones sufrían: síndromes genéticos [6 casos (21,4%)] y displasias esqueléticas [3 casos (10,7%)]. Trece tenían <6 años, 7 de ellos presentaron complicaciones (53,8%). Conclusiones: La instrumentación cervical en pacientes <10 años demostró ser un procedimiento factible y seguro. Las displasias vertebrales, las anomalías congénitas y los síndromes genéticos, sumados al factor edad <6 años, son las principales variables asociadas a las complicaciones observadas.

Introduction: pediatric cervical spine implants and construction designs had rapidly evolved in the last decade. Anatomic and biomechanical differences between pediatric and adult cervical spine require a thorough preoperative planning, because these implants were originally designed for adults. The objective of this study was to assess the postoperative results of cervical instrumented fusion in children under 10 years old, and to describe the surgical technique and complications. Methods: Twenty-eight children with different cervical pathology treated with instrumented fusion were evaluated. The following procedures were used: Roy-Camille’s and Magerl’s techniques for lateral masses, Goel-Harms’ technique for C1-C2 fusion, and occipital-cervical fusion with occipital plates or screws. Inclusion criteria were: children under 10 years, no prior spine surgery, and minimum follow-up of 2 years. Results: Sample included 17 girls and 11 boys, with a mean follow-up of 3.8 years (range 2-10). Mean age was 6.1 years (range: 1.6-10). Overall complication rate was 32.1%. The highest complication rates were associated with: genetic syndromes [6 cases (21.4%)], skeletal dysplasias [3 cases (10.7%)]. Thirteen patients were <6 years, 7 of them had complications (53.8%). Conclusions: Cervical instrumented fusion in patients <10 years old proved to be a feasible and safe surgical procedure. Vertebral dysplasias, congenital, syndromic anomalies, and being younger than 6 years old are the main factors associated with high complication rates.

Influence on postoperative axial symptom by unilateral laminoplasty combined with different fixations / 医疗卫生装备

Objective To observe the influence of preoperatively physical curvature abnormality and different fixation systems on postoperative axial symptom (PAS) and union rate of hinge groove after unilateral expansive laminoplasty for the patient with cervical spondylotic myelopathy (CSM).Methods The study reviewed 106 CSM patients who underwent unilateral laminoplasty supplemented by lateral mass or pedicle screw/rod fixation with a minimum of 36 months of follow-up.According to being complicated with physical curvature abnormality or not,the incidence,initial onset,severity,duration of PAS and union rate of hinge groove at postoperative 6 months were respectively compared to analyze the influences of two internal methods on the features of PAS.Results For 50 cases without physical curvature abnormality,fusion rates of hinge groove in pedicle placement group was higher than that in lateral mass fixation group,the P value reached statistical difference (t=142.2,P=0.032).Duration of PAS in pedicle group was shorter than that in lateral mass group,the difference reached statistic significance (t=147.2,P=0.019).For 56 cases of with physical curvature abnormality,incidence of PAS in pedicle group presented was lower than that in lateral mass group,the difference achieved statistic significance (x2=3.89,P=-0.042).Conclusion Whether concomitant with physical curvature abnormality or not,pedicle fixation would be beneficial to promoting bony fusion of hinge groove,shortening duration of PAS and reducing incidence of PAS in contrast to lateral mass fixation to some extent after unilateral laminoplasty for treating CSM patients.

The effects of cervical spinous process fracture with posterior ligamentous complex injury on stability of the goat cervical spine / 医用生物力学

Objective To investigate the effect of cervical spinous process fracture with posterior ligamentous complex (PLC) injury on biomechanical stability of the goat cervical spine specimen in vitro,and evaluate the role of posterior structure in maintaining the stability of cervical spine.Methods Twenty-four fresh goat cervical spine C3-6 specimens were randomly and evenly divided into 3 groups:control group (group A),simple cervical spinous process fracture group (group B) and cervical spinous process fracture with PLC injury group (group C).Under loading of 1.5 N · m torque,the range of motion (ROM) in each group was respectively measured under 6 working conditions:flexion,extension,lateral bending and axial rotation,and the ROM differences among 3 groups were compared by using one-way ANOVA analysis.Results Simple cervical spinous process fracture had little effect on the stability of cervical spine and there was no significant difference in ROM between group B and control group (P ＞ 0.05) under all working conditions.Compared with control group,the ROM in flexion,extension and axial rotation significantly increased in group C (P ＜ 0.05),and no significant ROM difference was found in lateral bending between control group and group C (P ＞ 0.05).Conclusions Simple cervical spinous process fracture does not affect the overall stability of cervical spine.Cervical spinous process fracture with PLC injury is more likely to cause cervical instability than simple cervical spinous process fracture,and surgical intervention is required in cervical spinous process fracture with PLC injury.

New Radiographic Index for Occipito-Cervical Instability

STUDY DESIGN: Retrospective study. PURPOSE: To propose a new radiographic index for occipito-cervical instability. OVERVIEW OF LITERATURE: Symptomatic atlanto-occipital instability requires the fusion of the atlanto-occipital joint. However, measurements of occipito-cervical translation using the Wiesel-Rothman technique, Power's ratio, and basion-axial interval are unreliable because the radiologic landmarks in the occipito-cervical junction lack clarity in radiography. METHODS: One hundred four asymptomatic subjects were evaluated with lateral cervical radiographs in neutral, flexion and extension. They were stratified by age and included 52 young (20-29 years) and 52 middle-aged adults (50-59 years). The four radiographic reference points were posterior edge of hard palate (hard palate), posteroinferior corner of the most posterior upper molar tooth (molar), posteroinferior corner of the C1 anterior ring (posterior C1), and posteroinferior corner of the C2 vertebral body (posterior C2). The distance from posterior C1 and posterior C2 to the above anatomical landmarks was measured to calculate the range of motion (ROM) on dynamic radiographs. To determine the difference between the two age groups, unpaired t-tests were used. The statistical significance level was set at p<0.05. RESULTS: The ROM was 4.8+/-7.3 mm between the hard palate and the posterior C1, 9.9+/-10.2 mm between the hard palate and the posterior C2, 1.7+/-7.2 mm between the molar to the posterior C1, and 10.4+/-12.1 mm between the molar to the posterior C2. There was no statistically significant difference for the ROM between the young- and the middle-aged groups. The intra-observer reliability for new radiographic index was good. The inter-observer reliability for the ROM measured by the hard palate was low, but was better than that by the molar. CONCLUSIONS: ROM measured by the hard palate might be a useful new radiographic index in cases of occipito-cervical instability.

Cervical single open door laminoplasty with lateral mass screw fixation for the treatment of cervical spondylotic myelopathy with cervical instability / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the outcomes of single open door laminoplasty with lateral mass screw fixation in treating cervical spondylotic myelopathy (CSM) with cervical instability.</p><p><b>METHODS</b>From March 2010 to October 2012, 25 patients with spondylotic myelopathy and cervical instability underwent single open door laminoplasty with lateral mass screw fixation. There were 18 males and 7 females, aged from 57 to 68 years with the mean of 57 years. Japanese Orthopaedic Association (JOA) scores were used to evaluate clinical effects before operation and final follow up. Radiographical measures were made in change of Cobb angle by sagittal plane from C₂ to C₇, and cervical range of motion.</p><p><b>RESULTS</b>All the patients were followed up from 18 to 36 months with an average of 25.6 months. Cerebrospinal fluid leakage occurred in 1 case, incision fat necrosis in 1 case, C₅ nerve root palsy in 4 cases. JOA scores was improved from preoperative 5.2±2.1 to 11.3±2.4 final follow up. Cobb angle was changed from preoperative (6.5±3.4)° to (13.2±4.9)° final follow up. Cervical range of motion was changed from preoperative (30.4±9.2)° to (26.5±8.4)° final follow up.</p><p><b>CONCLUSIONS</b>As an effective treatment to CSM with cervical instability, single open door laminoplasty with lateral mass screw fixation has the advantage of extensive application scope, safety and steady, but the incidence rate of complication must be reduced.</p>

Mid-Term Results of Computer-Assisted Cervical Pedicle Screw Fixation

STUDY DESIGN: A retrospective study. PURPOSE: The present study aimed to evaluate mid-term results of cervical pedicle screw (CPS) fixation for cervical instability. OVERVIEW OF LITERATURE: CPS fixation has widely used in the treatment of cervical spinal instability from various causes; however, there are few reports on mid-term surgical results of CPS fixation. METHODS: Record of 19 patients who underwent cervical and/or upper thoracic (C2-T1) pedicle screw fixation for cervical instability was reviewed. The mean observation period was 90.2 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 years after surgery. Postoperative computerized tomography was used to determine the accuracy of screw placement. Visual analog scale (VAS) for neck pain and radiological evidence of adjacent segment degeneration (ASD) at the 5-year follow-up were also evaluated. RESULTS: Mean JOA score was significantly improved from 9.0 points before surgery to 12.8 at 5 years after surgery (p=0.001). The C2-7 lordotic angle of the neutral position improved from 6.4degrees to 7.8degrees at 5 years after surgery, but this was not significant. The major perforation rate was 5.0%. There were no clinically significant complications such as vertebral artery injury, spinal cord injury, or nerve root injury caused by any screw perforation. Mean VAS for neck pain was 49.4 at 5 years after surgery. The rate of ASD was 21.1%. CONCLUSIONS: Our mid-term results showed that CPS fixation was useful for treating cervical instability. Severe complications were prevented with the assistance of a computed tomography-based navigation system.

Proteoglycan and collagen type Ⅱ in the adjacent intervertebral disc of the cervical instability models / 中国组织工程研究

BACKGROUND:Cervical decompression and fusion internal fixation wil accelerate adjacent segment disc degeneration, and it is not clear whether single segment instaibility can increase the adjacent segment disc degeneration. OBJECTIVE:To study the changes of morphology, proteoglycan and col agen type Ⅱ in the adjacent intervertebral disc of the cervical instability models. METHODS:Sixteen New Zealand white rabbits were divided into two groups randomly, with eight rabbits in the control group and eight rabbits in the model group. The animal cervical instability models were made by destroyed partly annulus fibrosus and absorbed C 5/6 nucleus pulposus through anterior cervical puncture. After 12 weeks, the animal models were tested by X-ray film. Al rabbits were sacrificed and 10 mg nucleus pulposus of the intervertebral discs of C 4/5 cut from sagittal plane were harvested and stored under 0 ℃. The content of proteoglycan in nucleus pulposus was tested with phloroglucinol method. Then, the paraffin sections of intervertebral disc tissues were taken for hematoxylin-eosin staining and SABC immunohistochemical staining. RESULTS AND CONCLUSION:The notochord cells of C4/5 intervertebral discs in the experimental group was decreased, and being replaced by fibroblast-like cells. Round chondrocytes could be seen occasional y and intervertebral discs annulus fibrosus became rough and arranged disorderly, the hyaline degeneration and pigmentation were observed as wel as the fibrochondrocytes, and there was a gap between inner and outer annulus fibrosus. The content of proteoglycan was decreased in the nucleus pulposus, and there was significant difference between two groups. The col agen type Ⅱ in the degenerative disc nucleus pulposus and annulus fibrosus of the experimental group was lower than that of the control group. Cervical instability can lead to adjacent intervertebral disc degeneration with the morphological changes and decreased content of proteoglycan and col agen type Ⅱ.

Effect of Cervical Stability Training on Cervical Vertigo / 中国康复理论与实践

@#ObjectiveTo investigate the effects of cervical stability training on cervical vertigo. Methods67 patients were divided into 2 groups. The experiment group was treated with Neurac (neuromuscular activation) for cervical stability training, meanwhile, the control ones with manipulation. They were assessed with clinical assessment and fall index before and 14 d after treatment. ResultsThe scores of clinical assessment and value of fall index were significant improved more in experiment group than in controls （P＜0.05）. ConclusionSpecific cervical stability training is effective on cervical vertigo based on cervical instability and proprioceptive disorder.

Resultado en el tratamiento quirúrgico de la inestabilidad atlantoaxoidea / Results of the surgical treatment of atlantoaxial instability

Introducción: La inestabilidad de la columna cervical es el aumento en la movilidad más allá de los límites fisiológicos de una vértebra sobre otra en alguno de sus ejes, que condiciona síntomas en el paciente. Existen causas traumáticas, degenerativas, metabólicas y neoplásicas. Material y métodos: Se realizó estudio retrospectivo, longitudinal, observacional y descriptivo, de intervención deliberada, en pacientes con cirugía por inestabilidad atlantoaxoidea, de enero de 1993 a mayo de 2002, con un seguimiento mínimo de cinco años. Resultados: Se evaluaron 11 pacientes, con edades de 25 a 75 años, media de 56 años. El sexo predominante fue el femenino. La etiología fue iatrogénica en seis casos, cuatro por artritis reumatoide y uno postraumática. En todos se realizó fijación y artrodesis occipitocervical con resección del arco posterior. El déficit neurológico preoperatorio predominante según la escala de Ranawat fue grado II, y en el posoperatorio fue grado I. Conclusiones: La edad media de nuestra serie fue discretamente menor respecto a la indicada en la literatura; el sexo predominante correspondió a lo informado en la literatura. Existió mejoría en ocho de los 11 pacientes, como en otras series. La mayor incidencia se observó entre los 30 y 64 años. La actividad ocupacional con mayor frecuencia fue la del hogar. El déficit neurológico según la escala de Ranawat mejoró en 72 % de los pacientes.

BACKGROUND: Instability of the cervical spine is defined as an increase in flexibility farther than the physiological limits of one vertebra over another in some of its axes, conditioning symptoms for the patient. Traumatic, degenerative, metabolic and neoplastic causes have all been identified. METHODS: A retrospective, longitudinal, observational and descriptive study was carried out on patients surgically intervened specifically for atlantoaxial instability from January 1993 to May 2002, with a minimum 5-year follow-up. RESULTS: Eleven patients were evaluated. Ages ranged from 25 to 75 years (average age 56 years) with a female predominance. Etiology was iatrogenic in six cases, and there were four cases of rheumatoid arthritis and one case due to trauma. In all cases, fixation was accomplished with occipitocervical arthrodesis with posterior arch resection. Predominant preoperative neurologic deficit according to Ranawat was grade II and postoperatively was grade I. CONCLUSIONS: The average age of patients in our series was discreetly lower in regard to what has been reported in the literature. Female predominance was in accordance with previous publications. Eight of 11 patients showed improvement as in other series. A higher impact was observed in patients between 30 and 64 years of age. The occupational activity with the highest frequency was homemaker, and the neurologic deficit according to Ranawat showed improvement in 72% of the patients.

Biomechanics of Cervical Spine

A through understanding of the biomechanics of the cervical spine is necessary to apply its knowledge to management of cervical disorders intelligently. In this article authors tried to fully review the biomechnics of cervical spine by, first, going over the basic anatomical and physiological characteristics of the cervical spine. Then, with these in mind, related kinemtics are reviewed with discussion of some of important clinical applications related to these facts. Finally, diagnostic points of cervical instability are stressed which can be used some of the guidelines in management of such patients in actual clinical situations.