Experimental Study And Clinical Application Of The Anterior Cervical Uncinate Decompression And Modified Bone Graft

【Background】Anterior cervical decompression and interbody fusion is a classic treatment method of cervical spondylosis, The factors of decompression and bone fusion are related to the postoperative curative effect , and fusion successfully depends on the graft material and the size of contact area. Autogenous iliac is the gold standard for bone graft in anterior cervical fusion. But the source is limited, and bring about the inevitable complications caused by bone harvest. Many scholars keen to research new bone graft substitute materials, any of them can perfectly replace the autogenous iliac now. Few people attempt to improve the graft technique, the graft interface is far less then the vertebral cross-sectional area when perform the routine anterior corpectomy and fusion (RACF). Does it can improve the fusion rate by increasing the size of contact interfacr? Does the disadvantage of using other repalced material can be neutralized by the advantage of increasing the size of contact interfacr? To answer the question, we modify the traditional surgical procedure, to perform the uncinate decompression and modified bone graft (UDMBG) technique, the specific methodology is the uncinate decompressions and used allo-fibula strut filled with local auto-bone dust and local cancellous chunks of corpectomy bone placed into the decorticated uncinate regions bilaterally. The goats were selected to be the animal model to accept this sugical procedue to observe the bone fusion, and perform it in the paient followed.【Objectives】1. To research the outcome of the modified bone graft method and the final result of allofraft. 2. To find out a method which can contribute to enhance the fusion rate without the bone harvest complications.【Methods】1. As the experimental animal, total 18 goats, were divided into A B C three groups randomly , six in each group. The UDMBG was performed in group A, Single anterior cervical vertebral corpectomy and fibular allograft bone graft followed in group B , RADF was performed in group C . X ray(anterior-posterior, flexion and extension lateral) films was used to evaluate the fusion result in 3 months, 6 months and 12 months postoperatively respectively. If fusion in X ray, CT scan examination followed. Execute the goats in 12 months postoperatively, to observe the fusion situation and final outcome of the allograft through the gross appearance and pathological section. 2. Reviewed the case histories of 137 patients that underwent surgical treatment for 2-level cervical spondylosis from July 2008 to June 2009. These patients were divided into two groups according to the operation methods, Group A included 61 patients, who underwent uncinate decompressions and used allo-fibula strut filled with local auto-bone dust and local cancellous chunks of corpectomy bone placed into the decorticated uncinate regions bilaterally. Group B included 76 patients, who underwent RACF with iliac crest autograft. All patients were fixed with semi-rigid plates. Perioperative parameters (days of hospital stay, bleeding amount, operation time, complication), fuctional parameters (NDI, VAS scores), and radiologic parameters (segmental height, cervical lordosis, arthrodesis rate) were compared.【Results】In animal experiments, 1 cases of goats fusion in group A, 0 cases in group B, 2 cases in group C in 3 months postoperatively; 4 cases of goats fusion in group A, 1 cases in group B , 5 cases in group C in 6 months postoperatively; All goats fusion in groupA and C, while just 4 cases in group B in 12 months postoperatively. The fusion rate of group A and C is similar, higher than in group B obviously. The radiologic results were confirmed by the gross appearance and pathological section in 12 months, the abnormal osteogenesis had not been found and auto-grafting bone pieces without fall off. The allograft was absorbed and reconstructed in 12 months, while bone fusion was established in four corners located in the medial of luschka joints. In clinical application, Operation time (P<0.05), days of hospital stay(P<0.05) and complication rate(P<0.05) were significantly lower in the group A. The bleeding amount was not different, The improvement in NDI was not different, , The segmental height and the Cobb angles were similar. 58 cases(95.1%) fused in group A at 1 yr postop, 1 pts were asymptomatic, 2 pt had slight neck pain. All pts in group B achieved arthrodesis, 10 had hematoma and 1 infection after iliac bone harvest in group B.【Conclusions】1. The area of autogeneous bone graft - autogeneous bone interface which increased in UDMBG will conduce to the high fusion rate, while complications caused by bong harvest in RACF were avoided completely; 2. The cervical spine will be stabilized when the autogeneous bone graft - autogeneous bone interface fusion successfully; 3. UDMBG applied to the cervical spondylosis especically combined the osteophyte of the uncovertebral join and neural foraminotomy stenosis. And decreased operative time and shorter hospital stay significantly, Particularly, It could avoid the morbidities.