RESUMO
BACKGROUND:Ankylosing spondylitis is a chronic inflammatory disease with chronic rheumatic immunity.Soft tissue ossification and fusion and spinal stiffness can cause biomechanical changes. OBJECTIVE:To reconstruct the lumbar-sacral intervertebral disc in ankylosing spondylitis patients with lumbar kyphosis by finite element analysis,and to study the range of motion of each segment of T11-S1 and the biomechanical characteristics of annulus fibrosus and nucleus pulposus. METHODS:The imaging data were obtained from an ankylosing spondylitis patient with lumbar kyphosis.The original CT image data of continuously scanned spine were imported into Mimics 21.0 in DICOM format,and T11-S1 was reconstructed respectively.The established model was imported into 3-Matic software in the format of"Stl"to reconstruct the intervertebral disc,and the fibrous intervertebral disc model was obtained.The improved model was further imported into Hypermesh software,and the vertebra,nucleus pulposus,annulus fibrosus and ligament were mesh-divided.After the material properties were given,the model was imported into ABAQUS software to observe the range of motion of each vertebral body in seven different working conditions of T11-S1,and analyze the biomechanical characteristics of each segment of annulus fibrosus and nucleus pulposus. RESULTS AND CONCLUSION:(1)The range of motion of L1 vertebrae was higher than that of other vertebrae under six different working conditions:extension,forward flexion,rotation(left and right),and lateral flexion(left and right).The maximum range of motion was 2.18° during L1 vertebral flexion,and the minimum range of motion was 0.12° during L5 vertebral extension.(2)The annular fiber flexion at L2-L3 segments was greater than the extension(P<0.05),and the annular fiber flexion at L3-L4 and L4-L5 segments was less than the extension(P<0.05).The left rotation of L1-L2 annular fibers was greater than the right rotation(P<0.05).The left flexion of the annulus was greater than the right flexion in L1-L2,L2-L3,L3-L4,L4-L5 and L5-S1 segments(P<0.05).(3)The nucleus pulposus stresses of T11-L12,L1-L2,L2-L3,L3-L4 and L4-L5 segments in forward flexion were greater than in extension(P<0.05).The left rotation of T12-L1 and L3-L4 segments was smaller than the right rotation(P<0.05),and that of T11-T12,L1-L2,and L2-L3 segments was larger than the right rotation(P<0.05).The left flexion was larger than the right flexion in the T11-S1 segment.(4)It is concluded that in ankylosing spondylitis patients with lumbar kyphosis,the minimum range of motion of the vertebral body is located at the L5 vertebral body in extension.To prevent fractures,it is recommended to avoid exercise in the extension position.During the onset of lumbar kyphosis in patients with ankylosing spondylitis,the maximum stress of the annulus fibrosus and nucleus pulposus is located in the L1-L2 segment,which is fixed and will not alter with the change of body position.The late surgical treatment and correction of deformity should focus on releasing the pressure of the annulus fibrosus and nucleus pulposus in this segment to avoid the rupture of the annulus fibrosus and the injury of the nucleus pulposus.
RESUMO
In recent years, robot-assisted surgery (RAS) has developed rapidly and become one of the hot topics in clinical research. Compared with traditional surgery, RAS has advantages in terms of minimal invasiveness, aesthetics, and functional preservation, and has been gradually applied in clinical practice such as neurosurgery, urology, and head and neck surgery. In the treatment of head and neck tumors, RAS can effectively minimize the surgical injury and accelerate postoperative recovery. This article reviews the application of RAS in the resection of primary lesions of head and neck tumors, neck dissection, and reconstruction of tissue defects.
RESUMO
Objective To investigate the approaches and effect of Ilizarov external fixators combined with limited operation in treatment of posttraumatic clubfoot in children.Methods The study involved 40 cases (43 feet) of posttraumatic clubfoot treated with Ilizarov external fixators combined with limited operation including soft-tissue releases (26 cases,28 feet) or osteotomies (14 cases,15 feet)from January 2006 to June 2012.Scoring system of intemational clubfoot study group (ICFSG) including aspects of functional assessment (36 points),morphology (12 points) and radiological assessment (12points) were employed before and after surgery.Results All the cases were available to the follow-up of 0.5-6 years.ICFSG score was excellent in 28 feet,good in 10,fair in four and poor in one foot,with excellent-good rate of 88％.This suggested the good correction of posttraumatic clubfoot,satisfactory weight-bearing exercise and a low relapse rate.Conclusions Conservative open operation brings large trauma and poor results in treatment of posttraumatic clubfeet in children,while Ilizarov invasive distraction technique is probable to offset those weak points.Therefore,Ilizarov external fixators combined with limited operation is an effective treatment.