Feasibility Analysis And Anatomical Basis Of Lateral Percutaneous Endoscopic Cervical Foraminotomy For Cervical Spondylotic Radiculopathy

?Objective?At present,the main minimally invasive treatment for cervical spondylotic radiculopathy is anterior percutaneous endoscopic cervical discectomy(APECD)or posterior percutaneous endoscopic cervical discectomy(PPECD).APECD can be divided into trans-disc approach and trans-vertebral approach.Trans-disc approach can effectively remove the herniated disc tissue,but there may be more loss of disc height.Due to the limitation of cervical anatomical structure,PPECD mostly decompression of the posterior wall of the intervertebral foramen and enlargement of the intervertebral foramen to alleviate symptoms,so it's indirect decompression.Therefore,we proposed a new surgical approach-the lateral uncovertebral joint approach,to explore the feasibility without damaging intervertebral discs and bone structures while decompressing them directly using cadaveric specimen.?Method?A fresh frozen cadaver infused with arterial latex were selected as prospective subjects.(1)Complete endoscopic surgery was simulated in the neck of the specimen.(2)After the completion of endoscopic surgery,the neck of the specimen was carefully dissected to explore the adjacent relationship of the tissue structure around the surgical segment?Results?(1)It is easier to reach the intervertebral foramen area and expose the corresponding nerve roots by the lateral approach of the uncovertebral joint guided by the endoscopic system.(2)As seen in the endoscopic system,the C7 nerve root originates from the C6-7 intervertebral foramen and travels from the inside top to the outside bottom.During endoscopic surgery,the vertebral artery was not seen in the surgical field,and the vertebral artery intersected with the C7 nerve root in front after lifting the endoscopic sleeve.(3)Gross anatomy: the skin,sternocleidomastoid muscle,carotid artery sheath,scalenus anterior and medial muscles,brachial plexus nerve and vertebral artery were seen from the superficial to the deep level of the neck.Through an endoscopic incision,the skin was further incised to reveal the platysma muscle,which was cut off to peel off to the deep surface and both sides to reveal the sternocleidomastoid muscle.The sternocleidomastoid is formed from the outside to the inside and has two heads: the thoracic bone is tendinous and slightly narrow,arising from the front of the upper margin of the sternum;the clavicle head is muscular and slightly wider,arising from the medial clavicle.Two bundles of muscle fibers terminate at the mastoid process and the superior occipital line.After the sternocleidomastoid muscle was cut off,the structure of the carotid sheath was seen,and the sheath was carefully detached.The whole length of the common carotid artery was located in the sheath together with the internal jugular vein and the vagus nerve.After the vertebral artery sheath was severed,the anterior and middle scalenus muscle and brachial plexus nerve could be seen coming out between them.The scalenus anterior muscle started from the anterior tuberosity of the C3-6 transverse process,and its fibers were slightly downward and outward,ending at the1 st medial costal margin and the scalenus tubercle.The scalenus medius arises from the posterior tuberosity of the transverse process at the C2-6segment and ends behind the subclavian artery sulcus above the first rib.The vertebral artery is seen after the anterior and medial scalenus muscles are separated.The vertebral artery starts from the subclavian artery,moves upward and inward,enters the C6 transverse foramen at the C6 segment,and continues ascending at a relatively fixed position.After the C7 nerve root is sent from the spinal cord,it travels from the inside up to the outside down and intersects with the vertebral artery.The nerve root is located at the deep surface of the vertebral artery.The distance between the c6/7horizontal vertebral artery and the outer edge of the c6/7uncovertebral joint is 6.8mm,which can accommodate the outer working sleeve of the endoscopic system.When the working sleeve extends to the vertebral artery,the included Angle between the working sleeve and the median line is 7 °,and the vertebral artery may move outward with the pushing of the working sleeve.The distance between the c5/6 level vertebral artery and the c5/6 uncovertebral joint is 1.6mm,the vertebral artery has almost no mobility,and the lateral operating sleeve of the endoscopic system cannot be accommodated.?Conclusion?(1)It is feasible to treat C6/7 cervical spondylotic radiculopathy via the lateral approach of uncovertebral joint,especially the cervical spondylotic radiculopathy caused by the proliferation of uncovertebral joint and the narrowing of intervertebral foramina.(2)The operation of nerve root decompression is relatively easy to reach the intervertebral foramen via the lateral of the vertebral body under endoscope.It is proved that endoscopic surgery has a relatively safe operating space from the adjacent relations of the uncovertebral joint,nerve root and vertebral artery.(3)Local anatomy showed that the C7 nerve root walked on the deep surface of the vertebral artery after coming out of the intervertebral foramen,but the vertebral artery was external and had a good mobility.It was not necessary to expose the vertebral artery when the working channel was used to separate to the deep surface.(4)At present,this operation method is not feasible for C3-6 segments.As the vertebral artery enters the transverse foramen of C6,the position is relatively fixed,and the operating space of the endoscopic system is small.(5)This technique can be performed on cadaver specimens,but whether it can be performed in clinical application remains to be confirmed by further studies.