title: [Clinical application of short-segment pedicle screw in treating degenerative L4 spondylolisthesis-relation of preliminary rod bending degree to lumbar lordosis angle, slipping angle and slipping percentage].
abstract: OBJECTIVE
  To investigate the short-segment pedicle screw in treating degenerative L4 spondylolisthesis and the relationship of the preliminarily bending degree of the titanium rod with the lumbar lordosis angle, the slipping angle and the slipping percentage and to evaluate the clinical coincidence and curative effects of the preliminarily-bent rod.
  
  
  METHODS
  From September 2005 to March 2007, 31 female patients (age, 40-70 years; average, 58.3 years) were admitted for surgical treatment of their L4 degenerative spondylolisthesis (Meyerding I degree, II degree). Their lumbar lordosis angle (x1), slipping angle (x2), and slipping percentage (x3) were measured in the L(4,5) segment before operation. During the operation, the titanium rod bent beforehand according to the corresponding standards was inserted. The angle of the bent rod (Y) was measured, and then the multiple linear regression equation was established. The regression equation was applied to the surgical treatment of the 30 patients.
  
  
  RESULTS
  According to the criteria in the JOA scoring system, the 31 patients had scores of 8.300 +/- 1.080 and 26.916 +/- 1.859 before operation and after operation, respectively. There was a significant difference between before operation and after operation (P < 0.05). The established multiple linear regression equation was as follows: Y = 0.1390 - 0.327 logx1 + 0.463x2 + 0.288x3(2). The operating time was 51.290 +/- 3.408 min in the 30 patients who underwent an insertion of the preliminarily-bent rod during the operation; however, the operating time was 102.360 +/- 5.004 min in the 31 patients who underwent an insertion of the bent rod that was made based on experience during the previous operations. There was a significant difference in the operating time between the two kinds of the rods (P < 0.05). Estimated according to 90%, 95% and 99% of the areas under the normal curve, the clinical coincidence rates in the preliminarily bending degrees of the titanium rod in the 30 patients were 80.00%, 90.00% and 96.67%, respectively.
  
  
  CONCLUSIONS
  The titanium rod that has been bent into a certain angle before operation according to the established criteria can definitely diminish its strain during operation and efficiently shorten the operating time. This kind of the titanium rod has a good coincidence in clinical application and can be effectively used in clinical practice. It is worth reference during the clinical operation.
authors.affiliation: Department one of Spine Surgery of Traditional Chinese Medical Hospital in Xinjiang uygur Autonomous Region, Urumqi Xinjang, 830000, PR China. xiaochu138@sina.com
authors.forename: Ge
authors.initials: G
authors.lastname: Chu
authors.forename: Jingping
authors.initials: J
authors.lastname: Bai
authors.lastname: Xilin
authors.lastname: Baoleri
mesh_terms: D000328:Adult; D000368:Aged; D001863:Bone Screws; D019299:Decompression, Surgical; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D018583:Pliability; D011300:Preoperative Care; D011859:Radiography; D013123:Spinal Fusion / Q000379:methods; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D014025:Titanium; D016896:Treatment Outcome
chemical_list: D014025:Titanium