| 1Background and ObjectiveCervical spondylosis is one common disease of orthopaedics, which usually refers to the signs and symptoms of the damage of spinal cord, spinal root, and blood vessels caused by the cervical intervertebral disc degeneration, and its secondary vertebra joint degeneration.Except for the cervical intervertebral disc degeneration,the cause of cervical spondylosis contains the acute and chronic injury and congenital cervical spinal stenosis,which can bring about the the signs and symptoms of cervical spondylosis. In clinical practice, the spinal cord and spinal root is the most common oppressed structure which will cause the signs and symptoms, and morbidity of cervical spondylotic myelopathy and cervical spondylotic radiculopathy is higher than the other two types. At present, there is no effective drugs can remove the oppression. So, the nonoperative treatment invalid cervical spondylosis or repeated ones as well as the cervical spondylotic myelopathy which are gradually aggravated should be performed operation timely. Especially, the patients with cervical spondylotic myelopathy should remove the spinal cord compression early to protect and improve the neural function when be clearly diagnosised, because the damage of spinal cord be compressed too long can lead to irreversible consequences. For posterior surgery can not resect the ossific tissue directly, anterior surgery is the priority, except many segments involved with spinal stenosis or Ossification of posterior longitudinal ligament (OPLL). From the first time the anterior cervical plate was used for the treatment of cervical vertebra trauma, it was immediately used widely because of its obviously effect. Subsequently, the anterior cervical plate was constantly developed and improved, and there appeared a variety of different anterior cervical plate system. The material is qualitative with titanium alloy primarily. Titanium alloy plates were widely used because of its excellent biocompatibility and corrosion resistance as well as not have magnetic. However, with the widely use of titanium alloy plate, complications caused by cervical spine fixation devices attracted more and more attention of the spine surgeon, For example, spinal nerve root injury caused by screw; stabbed esophageal or tracheal and the mediastinum inflammation caused by the screw or plate loose; the acceleration degeneration of adjacent segment caused by the fusion,which will lead to the reoccurring of the cervical spondylosis, etc. These complications once in place, not only increase the patients suffering and hospitalization time, but also greatly affect patients’satisfaction degree of the cervical spine surgery, and at the same time, increase the economic burden of the whole society,as well as consume more medical resources.Magnesium alloy steel plates’have excellent biocompatibility and biological mechanical properties, especially the absorbable properties, provide a new train of thought and method to solve these problems. Animal experiment found that a kind of magnesium alloys (Mg-2wt%Zn) with hydroxyapatite surface modification has the role of bone conduction and bone induction, and can be effectively controled the irrision rate,.It is considered as a kind of potential biodegradable metal material. The biomechanical evaluation report that this kind of magnesium alloys has not been seen now. Based on the analysis of the steel plate, absorbable magnesium alloys and biomechanical technology, we preliminary discussed the differences of the immediate stability between the magnesium alloy steel plate and the traditional anterior titanium alloys steel plate, and layed the foundation for further biomechanical study, so as to found a new type of alloy material to solve the clinical problems caused by the use of the anterior titanium alloy steel plate. 2Material and methods14goat cervical spine specimens were divided randomly into group A (magnesium alloys group) and group B(titanium alloys group).The range of movement and neutral zone of two groups of normal cervical spine specimen were measured under2.5Nm pure moment load.Two groups of cervical spine specimens were depressed by the trephine and fusicned with graft bone, then the magnesium alloys plates and titanium alloys plates were fixed respectively, and the range of movement and neutral zone of two groups were measured again..3Results1. There is no significant difference about the range of movement and neutral zone between the two groups of specimens (with two independent samples t-test, p>0.05), which demonstrates the variation of the two groups is acceptable.2. There is significant difference of the movement range between the magnesium alloy plate as well as titanium alloy plate fixed specimens and the normal station.(with two paired sample t-test, p<0.05), indicating that the range of movement was decrease after plate fixed in both two groups, the stability of the specimen of both groups was increased compared to normal condition.3. After fixed, there is no significant difference about the rang of movement and neutral zone between the two groups (with two independent samples t-test, p>0.05), showing that magnesium alloy plate have similar fixed effect with titanium one,which rebuild the stability of the postoperative cervical spine specimen in flexion, extension,rotation and lateral bending states.4ConclusionThe absorbable magnesium alloys as a kind of very potential biological material, can be made into anterior cervical plate and rebuild the postoperative stability which can meet the requirements of the immediate stability of the cervical vertebrae.Compared to the titanium alloys plate, the magnesium alloys plate can not only meet the requirements of the immediate stability of the cervical vertebrae, but also can be absorbed. So it is a kind of ideal materials for cervical fixation. |
PDF Full Text Request