| Objective: Ever since the basic operation of anterior cervical decompression and bone graft fusion was reported by Robinson and Smith in 1950s, this operation method has been performed widely in clinic and reformed unceasingly. Now it still is the main operation method for treating the cervical spondylotic myelopathy, although the prosthetic replacement technique of cervical disc just starts to develop.For a long time, the autogenous bone transplantation has been used in the anterior cervical decompression and bone graft fusion operation, and the disease of many patients was relieved or cured. But its some shortages were also revealed evidently during the general application in clinic, such as non-fusion of bone grafts, emersion and/or sinking of bone grafts, progressive cervical kyphosis and vertebral arrangement disorder. Moreover after autogenous bone was resected, 10-20% patients would bear some complications including the local pain, paresthesia or hyperesthesia and so on. The application of bone grafts and anterior cervical plates system (ACPS) makes the joint of bone grafts and endplates of cervical vertebra more stable, increases the fusion rate, retains the cervical physiological antecurvature and reduces the complications above-mentioned. The theory of interface fusion proposed in 1980s opens a new era of the cervical fusion cage. The cervical fusion cage not only avoids the complications caused by harvesting autogenous bone, but also gets the stability instantly, and makes a good condition for the bone fusion at last. Following the development of vitodynamics and material science, the interbody fusion cage is invented and made into various shape with different materials. How to select the operation type and the kind of material? How to play their advantage thoroughly and to improve the therapeutic effect? Should only the advanced methods and materials be pursued, but the basic theory is neglected? What is the key point influencing the operative effect? These questions will be answered basically in this study, which was performed through observing the therapeutic effect of some kinds of anterior cervical fusion and internal fixation on the cervical spondylotic myelopathy.Method: The retrospective analysis was completed on the clinical effective of 98 patients with integrated follow-up data, who suffered the cervical spondylotic myelopathy and received the treatment of bone graft fusion by anterior cervical approach in the department of spine, the third hospital of Hebei Medical University from Dec. 2005 to Dec. 2006. The follow-up time was 6-24 months (mean time was 16 months). All clinical data was divided into 4 groups basing on the way of fusion and internal fixation. Group A: single segment decompression, anterior plates and iliac bone graft fusion; Group B: single segment decompression, carbon fibre cage-assisted fusion; Group C: subtotal resection of multi-segment (2 or 3) of cervical vertebral bodies for decompression, anterior plates and iliac bone graft fusion; Group D: subtotal resection of multi-segment (2 or 3) of cervical vertebral bodies for decompression, anterior plates and titanium mesh bone fusion. One vertebral body was subtotally resected in double segments decompression, and two bodies were done in three segments decompression.The operative complications were observed and recorded, including spinal dural fistula, nerve root injury and so on. X-ray detection was performed on cervical vertebra at the 3rd day after operation for observing the location of bone grafts and interbody fusion cages. Meanwhile the stretch symptoms and injury symptoms of nerve root were also observed. Basing on the assessment standard of Japanese Orthopaedie Association (JOA), the JOA score of patients was recorded at the day on admission, the 3rd day after operation and the time of the last follow-up. And then the increase value of score after operation in each group was calculated and compared for evaluating the improvement level of spinal cord function. the increase of JOA score was calculated according to the equation: the increase of JOA score = the JOA score at postoperation–the JOA score at preoperation. All patients received the lateral X-ray photographs in neutral position at preoperation, the 3rd day after operation and the last follow-up. The cervical physiological curvature (D value) and the intervertebral height were measured at preoperation and postoperation basing on the photographs. For comparing the improvement of spinal cord fuction in 4 groups, the increase of D value was calculated according to the equation: the increase of D value = D value in postoperation– D value in preoperation.Meanwhile the bone fusion was also observed in postoperation. All results were expressed as means±SD ( x±s), and the statistical analysis was completed by one-way ANOVA and t-test with SAS6.12 software (α=0.05).Result: There is one patient who suffered the leakage of cerebrospinal fluid after operation due to the injury on dura mate of spinal cord in group D and E, respectively. But the wounds healed at the 14th day after operation through treatment. The X-ray at the 3rd day after operation showed no cacothesis of bone grafts and intervertebra cage, no stretch and injury symptoms of nerve roots could be found in clinic, and all patient got the bone fusion at the last follow-up. The X-ray results indicated that: at the 3rd day after operation and the time of the last follow-up, the increase of D value in group A was 2.3±0.4mm and 2.1±0.6mm respectively; in group B was 2.5±0.3mm and 2.4±0.5mm respectively; in group C was 3.6±1.1mm and 3.6±0.9mm respectively and in group D was 3.7±0.5mm and 3.6±0.9 mm respectively. At the 3rd day after operation and the time of the last follow-up, the increase of intervertebral hight in group A was 2.2±0.6mm and 2.2±1.4mm, respectively; In group B was2.3±0.4 mm and 2.3±1.1mm, respectively; In group C the increase of intervertebral hight of double segments was 2.6±0.8mm and 2.4±0.6mm, respectively. In group C the increase of intervertebral hight of three segments was 2.5±0.3mm and 2.4±0.9mm, respectively. In group D the increase of intervertebral hight of double segments was 2.7±0.8mm and 2.4±0.3mm, In group D the increase of intervertebral hight of three segments was 2.5±1.1mm and 2.4±0.6mm. According to the statistical analysis, the increase of D value and intervertebral hight had no significant difference in each group at the 3rd day after operation and the last follow-up (p>0.05); the increase of D value at the 3rd day after operation and the last follow-up had no significant difference between group A and B, and group C and D (p>0.05); but the increase of D value had statistical difference between group of single segment (group A and B) and group of multi-segment (group C and D) at the 3rd day and the last follow-up (p<0.05). there was no difference in the increase of intervertebral hight between group A and B at the 3rd day and the last follow-up(p>0.05); there was no difference in the increase of D value and intervertebral hight of double segments between group C and D at the 3rd day and the last follow-up(p>0.05); and no significant difference in the increase of D value and intervertebral hight of three segments between group C and D at the 3rd day and the last follow-up(p>0.05).The result of JOA score showed that: the increase of JOA score at the 3rd day after operation had no significant difference with it at the time of the last follow-up in each group (p>0.05), and there was no difference among groups too (p>0.05).Conclusion: To improve the therapeutic effect of anterior cervical approach surgery on the cervical spondylotic myelopathy, the key pionts includes the earlier surgical intervention, strict surgical indications, sufficient decompression and normal intervertebral hight recovery. The influence of internal fixation methods on the therapeutic effect shouldn't be emphasized.
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