| Non-combat diseases and injuries are the major causes of modern military attrition.Cervical spondylosis is a common disabling disease among military pilots.With the improvement of aircraft flight speed and performance,the load borne by flight personnel has increased significantly,and the increasing training intensity of flight personnel has led to the increasing incidence of cervical spine diseases year by year.The prevention and care of cervical spine diseases of flight personnel has attracted more and more attention of military medicine.Objective :(1)To investigate the hospitalization of cervical spondylosis among military pilots in active service,and to understand and analyze the hospitalization rate,diagnosis and treatment and medical identification of cervical spondylosis.(2)Finite element method was used to construct the postoperative model of cervical spine,and to explore the biomechanical response of ACDF and CTDR to cervical spine under high load.Methods and Results:Part I: A study on the current situation of hospital admission for cervical spine disease of military pilots.A single-center retrospective study was conducted on active flight personnel hospitalized with cervical spondylosis in our hospital from January 2010 to December2019.After inclusion and exclusion criteria,descriptive statistics and analysis were conducted on the age,gender,aircraft type,flight time,disease classification,diagnosis and treatment,and flight identification results of the included subjects.The results showed that the proportion of cervical spondylosis in orthopedic diseases of flight personnel in 2010-2014(21.36%)was significantly higher than that in the next five years(15.53%),but the number of inpatients with cervical spondylosis(148)was lower than that in 2015-2019(193),with statistical difference(P < 0.01).From January 2010 to December 2019,a total of 166 active military flight personnel with cervical spine diseases were admitted to our hospital after repeated hospitalizations were removed,which accounted for 17.61% of the total diseases in the department of orthopedics,ranking the second place,and was much higher than the number of cervical vertebrae of non-air military personnel hospitalized in the same period,with statistical difference(P< 0.001).The age of onset of cervical spondylosis in flight personnel ranged from 23 to57 years old,with an average age of 37.37±7.37 years old,which was lower than that of non-flight military personnel with an average age of 39.72±8.98 years old,with statistical difference(P < 0.05).Among 166 pilots,4 patients(2.41%)received surgical treatment,which was significantly lower than that of non-aircrew soldiers in the same period(12.09%),with statistical difference(P < 0.05).In the study,a total of 87(52.41%)of the 166 flight personnel passed the flight and returned to work;Fifty-three pilots were temporarily unqualified for flight and 26 were unqualified for flight and could not continue to fly.Part 2: Cervical biomechanical response of ACDF and CTDR internal fixation systems to high loads.The finite element method was used to construct a three-dimensional finite element model of cervical vertebrae bone-ligament-muscle on cadaver specimens that met the requirements,and the finite element model was verified.The ACDF and CTDR models constructed with C4-5 vertebral bodies were used as the experimental group,and the normal cervical model was used as the control group.The above validated model was used to simulate the high acceleration condition in flight training to study the force and kinematics effect of postoperative cervical spine.The results showed that the data constructed on flexion and extension,roll and rotation in this study were basically consistent with the experimental data in the literature,with an error of ±1 standard deviation,which proved that the established finite element model could effectively reflect the kinematics and mechanical response of human head and neck,and could be used in the biomechanical study of postoperative cervical spine under high load.The study showed that the disc stress in the control group increased gradually from top to bottom,and the disc stress in C7-T1 and C6-7 was the largest.In the ACDF group,the range of motion under high load was slightly lower than that of the normal cervical spine,while in the CTDR group,the range of motion at surgical segments was much higher than that of the normal cervical spine due to the separation of the upper and lower parts of the artificial intervertebral disc at the later stage of impact.Under load impact,the stress between adjacent vertebral bodies in the control group fluctuated the least over time,followed by ACDF,and CTDR.According to NIC injury criteria,ACDF and CTDR may not be at risk of spinal cord injury,but the risk of ligament and muscle injury may be increased relative to ACDF due to the late dissociation of the artificial disc in the CTDR group.Conclusion: The cervical vertebra diseases of flight personnel occupy the forefront of the spectrum of orthopedic diseases,and the onset age is younger,the treatment is relatively simple,and the qualified rate of flight after treatment is low.According to the results of this model experiment,ACDF(Zero-P)may be safer than CTDR(Prodisc-C)under the action of high load impact force.It has certain significance for the diagnosis,treatment and prevention of cervical vertebra disease and whether flight personnel can return to flight post after operation. |
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