title: [An imaging study on effect of total artificial disc replacement on lumbar sagittal alignment].
abstract: OBJECTIVE
  To investigate effect of Activ L total lumbar disc replacement on lumbar sagittal alignment.
  
  
  METHODS
  The imaging data of patients with degenerative disc disease received Activ L total lumbar disc replacement at Department of Orthopedics, Beijing Chao-Yang Hospital, Capital Medical University from March 2009 to March 2013 were retrospectively analyzed. The average age was 45.6 years(range, 35-60 years)and the surgery levels were as follows: L3-4 2 cases, L4-5 15 cases, L5/S1 5 cases, L3-4+ L4-5 3 cases, L4-5+ L5/S1 7 cases. All patients were followed up for 15 to 63 months(average, 32 months). Radiographic parameters such as lumbar lordosis angle(LL), segment lordosis angle(SL) and sacral slope angle(SS) were recorded. All the radiographic parameters were compared using one-way ANOVA at different stage. Lumbar lordosis angle of the two-level was compared with the one of one-level by using independent sample t-test before and after the operation. A partial correction test was carried out to determine the corrections between the parameters preoperatively, one month after the operation and at final follow-up.
  
  
  RESULTS
  One month after the operation, the lumbar lordosis angle decreased by an average of 1.8°, but there was no statistically significant(P>0.05). Compared with one month postoperation, the lumbar lordosis angle increased by an average of 6.8°(P<0.05), which also increased a lot compared with preoperation(P<0.05). The value of segment lordosis angle was rising up from preoperation to the final follow-up(P<0.05), so was the value of sacral slope angle, but there was no statistically significant between different stage(P>0.05). The lumbar lordosis angle showed no significant difference between double-level ones and single-level ones at different stage(P<0.05). The lumbar lordosis angle showed positive correlation with the sacral slope(P<0.001), however, the lumbar lordosis angle showed no corrected with the segment angle all the time(P>0.05).
  
  
  CONCLUSIONS
  The total lumbar disc replacement with Activ L prosthesis had contributed to maintain and improve the lumbar alignment in the short and medium term. Double- or single-level total lumbar disc replacement had no significant effect on the value of lumbar lordosis angle. The lumbar lordosis angle showed positive correlation with the sacral slope all the time with no correlation between lumbar lordosis angle and sacral slope.
authors.affiliation: Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Sun
authors.forename: Shibao
authors.initials: S
authors.lastname: Lu
authors.forename: Yong
authors.initials: Y
authors.lastname: Hai
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Wang
authors.forename: Nan
authors.initials: N
authors.lastname: Kang
authors.forename: Lei
authors.initials: L
authors.lastname: Zang
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Tie
authors.initials: T
authors.lastname: Liu
authors.forename: Dehua
authors.initials: D
authors.lastname: Liang
mesh_terms: D003952:Diagnostic Imaging; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000601:surgery*; D008141:Lordosis / Q000000981:diagnostic imaging; D008159:Lumbar Vertebrae / Q000601:surgery; D008161:Lumbosacral Region / Q000601:surgery; D011184:Postoperative Period; D019736:Prostheses and Implants; D011859:Radiography; D012189:Retrospective Studies; D059145:Total Disc Replacement