title: The effect of risedronate on posterior lateral spinal fusion in a rat model.
abstract: OBJECTIVE
  To evaluate the potential effects of risedronate (RIS) which shows a higher anti-resorptive effect among bisphosphonates, after a posterolateral lumbar intertransverse process spinal fusion using both autograft and allograft in a rat model.
  
  
  METHODS
  A totoal of 28 Sprague-Dawley rats were randomized into 2 study groups. A posterolateral lumbar intertransverse process spinal fusion was peformed using both autograft and allograft in a rat model. Group I (control) received 0.1 mL of steril saline (placebo) and Group II (treatment) received risedronate, equivalent to human dose (10 microg/kg/week) for 10-weeks period.
  
  
  RESULTS
  The fusion rates as determined by manual palpation were 69% in the group I and 46% in the group II (p = 0.251). According to radiographic score, the spinal segment was considered to be fused radiographically in 7 (53%) of the 13 controls and 9 (69%) of the 13 rats treated with RIS (p = 0.851). The mean histological scores were 5.69 +/- 0.13 and 3.84 +/- 0.43 for the control and treatment groups, respectively. There was a significant difference between the both groups (p = 0.001). The mean bone density of the fusion masses was 86.9 +/- 2.34 in the control group and 106.0 +/- 3.54 in the RIS treatment group. There was a statistical difference in mean bone densities of the fusion masses comparing the two groups (p = 0.001).
  
  
  CONCLUSIONS
  In this study, risedronate appears to delay bone fusion in a rat model. This occurs as a result of uncoupling the balanced osteoclastic and osteoblastic activity inherent to bone healing. These findings suggest that a discontinuation of risedronate postoperatively during acute fusion period may be warranted.
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, Abant Izzet Baysal University, Bolu, Turkey.
authors.forename: Ali Riza
authors.initials: AR
authors.lastname: Gezici
authors.forename: Rüçhan
authors.initials: R
authors.lastname: Ergün
authors.forename: Kamil
authors.initials: K
authors.lastname: Gürel
authors.forename: Fahri
authors.initials: F
authors.lastname: Yilmaz
authors.forename: Onder
authors.initials: O
authors.lastname: Okay
authors.forename: Omer
authors.initials: O
authors.lastname: Bozdoğan
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