Indirect Spinal Canal Decompression In Lumbar Vertebrae Burst Fractures Treated

Objective: Posterior reduction and stabilization of lumbar vertebrae burst fractures is known to increase the spinal canal area by realigning the retropulsed bone fragments. Reduction and posterior instrumentation is the most common surgical treatment. Although dependable decompression with only minimal residual encroachment has been obtained in some studies, It have not shown that the efficacy of Indirect Spinal Canal Decompression in lumbar vertebrae Burst Fractures(L1 L2 L3) which Spinal canal encroachment was more one third. No consensus exists as to the consistency and dependablity Spinal canal encroachment areas of such indirect decompression. controversy persists regarding pre-operative and postoperative Spinal canal areas diversity in indirect canal decompression. In this article, Prospective evaluation of spinal canal areas in consecutive burst fractures between L1 and L3 treated by reduction and stabilization with Pedicle Screw Instrumentation. Assessment of the efficacy of"indirect"spinal canal decompression in a large series of lumbarvertebrae Burst, and discuss possible determinants of successful reduction of encroaching fragments. Methods: 1.During a 3-year period (September, 2004 to Jan -uary, 2007), 53 patients with spinal injuries at lumbar vertebrae Burst Fractures(L1 L2 L3) which Spinal canal encroachment was more one third and Frankel E were operated on at our Department.2, The cross-sectional area of the spinal canal Encroachment and vertebrae Deformity was measured on the preoperative axial CT scans and radioactive ray at our Radiology Department .we write down clinical date,fracture type and spinal canal area preoperatively and postoperatively including patient name sex age level denis day of operation frankel grade Anterior and posterior vertebral height (AVH and PVH) the vertebral body angle (VBA) Cobb angle Anterior and posterior vertebral height (AVH and PVH) The cross-sectional area of the spinal canal Encroachment etc. 3 the operations were performed by three surgeons who were experienced in pedicle screw instrumentation in spinal trauma.4 we compute the date including increase value of canal, Cobb angle decrease value, decrease value of VBA, increase value of PVH, increase value AVH and bone fragment reduction rate.5 The Mann-Whitney U-test, Student t test, Spearman's rank correlation test, and multiple regression analysis were used for statistical analysis. P values less than 0.05 were considered significant. All confidence intervals (CI) are 95% intervals. it provided the evidence and set up theoretical base for clinical operation through The degree of encroachment was compared with clinical and radiographic variables for possible correlation.Results: 1.After surgery, the spinal canal area of all patients (N = 53) had increased, with the mean initial encroachment of 58% (range, 30-90%, CI53-62%) decreasing to39% (range, 10-70%, CI 34-43%) after surgery. the mean rate of bone fragment reduction is 32% (range,-9-84.61%, CI27-38%) .2.Postoperatively, mean encroachment was reduced from 56%(range, 33-87%, CI 50-63%)to 34%(range, 10-65%, CI(27 -41%)at L1, from 57%(range, 30.5-88%, CI 50-64%)to40%(range, 12.5-74%, CI 31-48% ) at L2, and from 61%(range,30-90%, CI 48-74%)to45%(range, 27-70%, CI 33-55%)at L3.3.The mean bone fragment reduction rate is 39%(range,0%-84 .61% ,CI,30-49%)at L1, 30%(range,-9%-75% CI20-39% at L2, 26%(range, 7.35%-55.56%,CI14-27%)at L3. 4.the mean rate of bone fragment reduction usually was better in patients Anterior vertebral height restoration than 85% (39%)than in less patients(14%). The difference was significant between the fracture subgroups (P = 0.000).5.difference in fragment reduction was observed between the day of operation longer six days(23%) and the day of operation shorter four days(38%).The difference was significant between the fracture subgroups (P = 0.008).6.Multiple regression analysis of fragment reduction and fracture level, fracture type, timing of surgery, restoration of AVH Cobb angle restoration of PVH showed restoration of AVH(P =0.026,r =0.312) , fracture level (P = 0.034,r =-0.279) and timing of surgery(P = 0.040,r =-0.253) to be significant determinants of outcome. Of all fracture reduction variables studied, restoration of AVH correlated best with the postoperative increase in canal area (r = 0.39, P = 0.03). By contrast to the Type B fractures, in Type A fractures increase in canal area was correlated with other reduction gains.Conclusion: Bone fragment reduction rate averages 32% by Indirect decompression in burst fractures .Bone fragment reduction rate correlated with restoration of AVH ,fracture level, timing of surgery. Results are usually better at L1 L2and than L3 . Additional or secondary decompression is rarely indicated if these fractures are treated early and by experienced surgeons.