| Part one Biomechanical analysis on cervical stability after anterior corpectomy and fusionObjective: It has been well documented about the techniques and outcomes in anterior operation for the ossification of the posterior longitudinal ligament(OPLL) in the cervical spine. The anterior corpectomy and fusion(ACCF) achieves better functional recovery than posterior approach, but with more surgery-related complications. The modified ACCF may be effective in the treatment of OPLL with short-level. However, the biomechanical analysis about modified ACCF has not been well reported. The purpose of this study is to investigate the biomechanical impacts on cervical stability after modified and traditional ACCF and to provide theoretical reference for clinical treatment.Methods : A total of twenty-four adult male goats C2-T1 cervical specimens were randomly divided into four groups:Normal group without any treatment,OPLL model group performed by puncturing with bone cements,One and a half-corpectomy group and Two-corpectomy group. Each group was consisted with six cases.After the preparation of specimens, the strain, axial-rigidity and twist-rigidty were measured using Bose Electro Force 3520-AT biomechanical machine during neutrality, fexion, extension and left/right bending. Differences of cervical stability among the four groups were compared using One-way ANOVA and Student-Newman-Keuls tests.Results:The short-level OPLL model could be prepared with injecting bone cements into the vertebral posterior cortex. ANOVA test showed that there was significant differences in the strain, axial- and twist-rigidity among the four groups(P<0.05).Both the strain and axial-rigidity in one and a half-and two-corpectomy groups were significantly superior than these in normal and OPLL model groups(P<0.05). The strain was smaller in one and a half-corpectomy group than that in two-corpectomy group, but without statistical difference(P>0.05). The axial-rigidity was larger in one and a half-corpectomy group than that in two-corpectomy group, but without statistical difference(P>0.05). There was no statistical difference about strain and axial-rigidity between short-level OPLL model group and normal group. However, the twist-rigidity in one and a half-corpectomy group was significantly superior than that in two-corpectomy group(P<0.05).Conclusion: The one and a half-corpectomy and reconstruction could significantly improve the postoperative strain and axial-rigidity of the cervical spine, and the twist-rigidity was significantly superior than that after two-corpectomy and reconstruction.Part two Anterior decompression techniques in the management of severe ossification of the posterior longitudinal ligament in the cervical spineObjective: The advantages of anterior decompression for severe ossification of the posterior longitudinal ligament(OPLL) in the cervical spine have been reported. However, it is more technically demanding and associated with a high risk of surgery-related complications. The purpose of this study is to evaluate the feasibility of resection unit according to preoperative CT scan and reconstruction, and to assess the security of longitudinal decompression techniques as “tongue flaps” for severe OPLL in the cervical spine.Methods:Between January 2010 and June 2012, twenty-two patients who underwent anterior corpectomy and fusion(ACCF) for severe OPLL were studied retrospectively. The vertebral body was divided into two equal parts, which was called resection unit. The longitudinal decompression was performed to remove the ossified mass. The clinical efficacy, occupying ratio(OR), fused segment height(FSH), and complications were all investigated.Results:There were 16 men and 6 women with average age of 56.5 years old(range of 45-72 years). The mean followed-up for was more than two years. Modified ACCF was performed in 16 patients with three resection units, while traditional ACCF was performed in 6 patients with four resection units. The mean JOA score increased from 8.8 preoperatively to 13.9 at final follow-up(P<0.05) with an improvement rate of 62.2%. Mean OR decreased from 60.2% preoperatively to 8.5% postoperatively(P<0.05). Mean FSH increased 2.2 mm from pre- to postoperatively and decreased 2.7 mm from postoperatively to final follow-up. Transient minor neurological deterioration happened in one case and cerebrospinal fluid leakage(CSFL) developed in five cases. One patient experienced hematoma. No instrument failure was observed, and all patients had successful fusion.Conclusion: Anterior corpectomy and fusion with longitudinal decompression techniques is a relatively effective procedure in the management of severe ossification of the posterior longitudinal ligament in the cervical spine. The neurological improvement was satisfied and more cervical vertebrae were retained. It can be applied to treat closed-base OPLL(defined as no space between the lateral margin of the ossified base and the spinal canal lateral wall), but it is associated with a high risk of cerebrospinal fluid leakage.Part three Midterm outcomes of modified and traditional anterior corpectomy and fusion in the treatment of cervical ossification of the posterior longitudinal ligamentObjective: The clinical and radiologic outcomes were reviewed to compare the efficacy of modified ACCF and traditional ACCF in the treatment of cervical ossification of the posterior longitudinal ligament(OPLL). The purpose of this retrospective study was to make sure the midterm outcomes of anterior decompression for OPLL, and simultaneously to investigate the potential benefits of modified ACCF.Methods:Between Junuary 2008 and June 2012, a total of 45 patients who underwent anterior decompression for cervical OPLL were divided into two groups. Group A(n = 25) underwent modified ACCF and group B(n = 20) traditional ACCF. Preoperative parameters(length of hospital stay, blood loss, operation time), clinical outcomes(JOA and VAS scores), radiological parameters(occupying ratio, fusion rate, segmental height, cervical lordosis)and complications were all reviewed and compared.Results:All patients were followed up for mean five years. Both group A and group B demonstrated significant increases in JOA scores and significant decreases in OR at the final follow-up. Patients who underwent modified ACCF experienced significantly shorter hospital stays(P<0.05), less blood loss(P<0.05), and shorter operation times(P<0.05). There were no significant differences about preoperative VAS, range of motion(ROM) of the cervical spine and cervical lordosis. But patients who underwent traditional ACCF experienced significantly more limit of ROM(P<0.05) and more severe neck pain(P<0.05), There were more loss of FSH and more titanium mesh subsidence in group A, but the surgical outcome and cervical curvature were not influenced. There were no significant differences in the incidence of complications among two groups.Conclusion: Anterior corpectomy and fusion provides satisfactory midterm clinical outcomes for cervical OPLL. Modified ACCF is associated with shorter hospital stays, less blood loss, and more cervical move function. Though the titanium mesh subsidence was occurred, it has no effect on surgical outcome and cervical curvature. When choosing the approach of modified ACCF, surgeon skills and related complications should be taken into consideration. |
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