Design And Development Of Posterior Cervical Lamina Space Distractor

BackgroundAt present,one of the main surgical methods for cervical degenerative diseases,such as multistage cervical spondylosis,cervical spinal stenosis,ossification of the posterior longitudinal ligament(opll),is extended decompression and plasty of the posterior cervical spinal canal,which has a history of more than 50 years and has achieved satisfactory clinical results in the treatment of cervical spondylotic myelopathy.Expanded decompression laminoplasty has different ways of opening the door,such as single-door,double-door and splitting the spinous process.Whether single or double-door,conventional surgical procedures need to be performed at the transition between the lamina and pedicle.Whether it is a high-speed grinding drill or a sharp biting forceps for grooving or opening,careful operation is needed to avoid thermal or blunt injury of spinal cord nerves in the spinal canal.However,due to the developmental morphology of sagittal physiological lordosis of cervical spine,especially in patients with large cervical lordosis angle,or differences in individual development,even if the patient is in the prone position of flexion before operation,the intervertebral space between the laminae in the adjacent stage after fully exposing the posterior column structure of cervical spine is still very small,and even the bilateral laminae of the adjacent segment overlaps partially.The operation space is further narrow,and according to the existence of "bowstring effect",the dural sac in the spinal canal will be close to the posterior wall of the spinal canal,i.e.the inner lamina on both sides,which also requires higher precision of operation.In addition,the occlusion of the lamina makes the operator unable to perform grooving or opening treatment under the direct vision ligamentum flavum or dura.Moreover,because of the relatively heavy operation tools,the operation force is not well grasped.It also increases the risk of spinal cord injury due to surgical procedures.Medical accidents such as dural rupture,cerebrospinal fluid leakage and even spinal cord nerve injury may occur.Although many orthopaedic surgeons solve this problem from the way of operation,they can find different complications in clinic by using different methods of operation.Up to now,there is no easy-to-use and easy-to-operate surgical tool that can be used to open the cervical laminar space in the anterior coronal position of cervical spine surgery.ObjectiveAt present,based on the use of pointed mouth osteotomy forceps,the purpose of seeking direct operation as far as possible is to design and develop a cervical posterior lamina space distractor.The model is applied in practice,and the actual effect is obtained through clinical practice,and the effectiveness of the distractor is compared and analyzed.The intervertebral space splitter can effectively reduce the risk of open and slotting operation of the lamina,and shorten the anesthesia time by saving the operation time,thus reducing the risk of operation and increasing the satisfaction of patients with the effect of operation.MethodDesigning and developing the cervical posterior lamina space distractor,and testing the actual mold and analyzing its effect.The main parts of this study are as follows:(1)Based on reviewing the previous literature and according to the actual clinical problems,a medical device which can effectively solve the problem is designed,and its design principle,characteristics and performance are described.(2)Designing the drawings of cervical posterior lamina space distractor,using the existing clinical imaging data and post-processing software to obtain relevant data,collect and analyze the data,and then complete the production of the model.(3)Specific methods of use: skin incision,muscle dissection,full exposure of the lamina and spinous process structure of cervical vertebra 3 to thoracic vertebra 1,treatment of the spinous process of cervical vertebra 2 and cervical vertebra 3 and the interspinal ligament between cervical vertebra 7 and thoracic vertebra 1.In sagittal position,cervical spinous process 2 is higher than cervical spinous process 3,wide and bifurcated,and there are naturally formed pits at the tail end.And downward tilt angle,here is a good distractor upper cervical spinous process chuck point.The cervical spinous process 2 was inserted between the vertical double C-shaped spinous process clamping grooves at the end of the distractor and fixed with the restriction screw to complete the positioning of the upper cervical spine.At the same time,the length of the adjusting nuts on both sides is rotated to the appropriate length of the stretcher,so that the thoracic spine 1 can enter the vertical double C-shaped spinous chuck at the tail end,which is the stress point at the tail end.Because the spinous process of thoracic 1 vertebral body is relatively straight,local treatment of thoracic 1 vertebral spinous process can be carried out,and a bone cortex is bitten in the middle of the cephalic side of thoracic 1 vertebral spinous process to form a depression,which is conducive to increasing the stability of distractor implantation.Then use restriction screw to fix.When the distractor is firmly fixed,the length of the adjusting nut is rotated in opposite direction,and the distance between the head and the tail C-arm is increased appropriately,so that the intervertebral space between the neck 2 and the thorax 1 is gradually opened.The degree of opening can satisfy the width required for inserting the biting forceps.During the stretching process,we should closely observe the phenomenon of nerve entrapment caused by manual operation,so as to adjust the stretching degree in time.After reaching the appropriate width of the intervertebral space,stabilize the distractor and perform the operation of slotting or opening the lamina.(4)Experiments were carried out on the model to compare the opening height of the intervertebral space before and after the use of the distractor.ResultThe clinical data collected were analyzed by SPSS21.0 software.SPSS21.0 software is used for statistics and analysis of the size data of the original parts in the decomposition state of the spreader and the size data in the use state.The design results are shown in the design drawings.Explain and demonstrate the connection mode and operation method of the spreader in use.Compare the opening height of the intervertebral disc space before and after the opening of the intervertebral disc space.ConclusionPosterior cervical lamina space distractor in orthopaedics is an effective tool for intervertebral space distraction.The cervical spinous process is fixed by the upper and lower spinous process slots.The four symmetrical oblique supporting rods on both sides can not only stabilize the distractor,but also to a certain extent extend the skin margin of the incision.By adjusting the length of the nut,the distance between the upper and lower spinous processes of distractor can be changed.Opening the narrow or overlapping cervical lamina space(coronal position),expanding the operative field of vision,facilitating the operation of lamina massage forceps,reducing the risk of operation caused by blind area of visual field,further increasing the safety and reliability of operation.It can effectively shorten the operation time and then shorten the recovery time of patients,increase the satisfaction of the operation effect,and increase the economic benefits.