Corresponding: The 2 nd Affiliated Hospital of Kunming Medical University, Kunming, Yunnan Province, P.R.

Transcription

1 Incidence and Risk Factors for Proximal Junctional Kyphosis(PJK)Following Posterior Vertebral Column Resection(PVCR)for Patients with Severe and Rigid Spinal Deformities-Minimum 2-Year Follow-up The Medical University, Kunming, Yunnan Province, P.R.China Corresponding: 1

2 Disclosures Authors: Jingming Xie Ying Zhang NI Bi Yingsong Wang Tao LI Zhi Zhao Zhiyue Shi 2

3 Background PVCR may be the best choice for the correction of severe and rigid spinal deformity. case1 Pre-o Po-o Po-3m Po-6m Po-12m Po-24m Po-36m Although PJK is a well-recognized postoperative phenomenon in adults and dolescents after scoliosis surgery,but there is less research focus on the incidence,mechanisms and risk factors for PJK in patiants undergoing PVCR. case2 3 Pre-o Po-o Po-6m Po-12m Po-18m Po-48m

4 Methods 86 patiants treated with PVCR with a minimum of 2 years of follow-up in a single institution between OCT,2004 and JULY, 2011 were reviewed retrospectively Some variables related to PJK, including clinical factors, imaging factors and operational factors, were analyzed using univariate analysis Multi-factor unconditional logistic regression analysis was used to identify the risk factors case Pre-o Po-o Po-3m Po-6m 4 Po-15m

5 Results X2: Age Total (N = 86) PJK (N = 11) P values Table 1 Single analysis ( positive result) <0.001 X3 : Etiology Tuberculou s kyphosis X4 : Scoliosis with kyphosis 14 8 <0.001 Yes X5:Locatio n of UIV Middle thoracic segments X6: resected vertabra resected vertabra X7:PJA >30 (Pre-op TK ) >40 (Po-op TK ) X10:UIV srew reservation Total (N = 86) PJK (N = 11) P values < Yes 58 1 <0.001 X11: contouring of the rods at the cranial ends Yes 57 Medical 1 University, <0.001 China

6 Results Table 2 Logistic regression model index for multiple factors Factors B S.E. P OR 95%CI X X X X X X X X constant

7 Results The change trend of PJA,LL, SSVL Pre-o PJA LL Sagittal balance Pre-op 0 Po-op Po-op 6 m Po-op 1 y Final FU 7 Po-o case4 Pre-o 2nd Affiliated Hospital of Kunming Po-o Po-3m

8 Results The mean PJA, LL and SSVL measured in patients with PJK shows a progressed deteriorate from 3 months early post-operative to 2 years follow-up, then indicats a trend towards a better outcome or stagnation in patients with long follow-up period. Case 5 Pre-o Po-o Po-o Po-3m Po-12m Po-24m

9 Discussion Incidence and mechanism for PJK following PVCR The incidence of PJK in this research is 12.7% which is lower than the report before. During the procedure of PVCR, resection of the columns of the vertebrae and spinal columns shortening can be performed.the innerstress which is contained in the abnormal spine can be released. Then the bow string effect on the anterior stucture of the abnormal spine eased and the stress in the junctional region can be reduced. Secondly,the correction,which is always at the cost of translation of the spinal cord, is obtained mainly through the space created by vertebrae columns resection and shortening instead of powerful posterior instrumentation. Thirdly,the good anterior column support and fusion reduce the stress of posterior tension banding structure Fourthly,the average age of this research is lower than the report before. 9

10 Discussion Risk factors for PJK following PVCR Tuberculosis kyphonsis is a independent risk factor of PJK. All the risk factors become more relevant when they coexist together or, when there is a pre-existent malalignment of the spine in the sagittal plane in the form of an already existing kyphosis. when the kyphosis is corrected insufficient,one of the spine sections will expose to PJK. This may occur in differt forms. PJK that appears to be a pathologic mechanism to compensate for surgically induced imbalance caused by overcorrection can be avoided if the postoperative kyphosis is at least 40. The screw on the UIV should be inserted till reserve one or two thread.this and contouring of the rods at the cranial ends between the high normal kyphosis range can avoid the impact between the screw and intervertebral facet joint,which is one of the causes of PJK. 10

11 Conclusions Despite the occurrence of PJK in 12.7% of spinal deformities undergoing PVCR, no significant differences were found in SRS-24 outcome scores in PJK and non-pjk patients. For the feature of PVCR, PJK was more common in young children with vertabra resected located on the thoracolumbar region. Tuberculous kyphosis,scoliosis with hyperkyphosis and pre-op TK 30 were identified as independent risk factors. A surgical strategy to minimize PJK may includ a correction within the high normal kyphosis range of The proximal junctional angles in PJK patients had showed a progressed deteriorate from 3 months early post-operative to 2 years follow-up, the proximal junctional angles then turned to keep unchanged or mostly improvement, and associated with increasing general lumbar curve,as well as the SSLV. 11

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