Simvastatin improves spinal fusion in rats.

OBJECTIVE: Statins stimulate bone formation by inducing the expression of bone morphogenetic proteins (BMP-2). The aim of our study was to investigate the effects of orally administered simvastatin on spinal fusion in rats. METHODS: Twenty rats were randomized into a spinal fusion group (SF) (n=10) or a spinal fusion and oral simvastatin administered group (SFS) (n=10). A spinal fusion was performed between L4-L6 representing two levels. Simvastatin (120 mg/kg/day) was administered orally in the SFS group. The rats were killed at the end of the 12 week study period. RESULTS: Manual palpation revealed two moderate fusions in the SF group. The SFS group did not reveal any signs of pseudoarthrosis. An average three-point bending force causing failure of fusion revealed results of 148.80±39.403 Newtons and 123.80±28.479 Newtons in SFS and SF groups, respectively (p>0.05). Histological examination revealed better fusion grades in the SFS group (mean: 9.30±0.949) than in the SF group (mean: 6.80±2.044) (p=0.003). Radiographic examination revealed Grade C fusion in two levels and Grade A fusion in 18 levels in the SF group. In the SFS group, Grade C fusion was detected in one level and Grade A fusions in 19. CONCLUSION: Our results suggest that simvastatin can promote spinal fusion and can be used as an adjunct to spinal fusion procedures in an elderly population with high cholesterol levels.

The "butterfly" suture technique for meniscal repair.

One of the important factors effecting meniscal healing is the strength of primary fixation obtained by repairing technique. From this perspective, it is important to choose the technique ensuring a higher primary fixation strength for meniscal repairs. We described a new technique for meniscal repair called "butterfly" technique using Viper device and hypothesized that high primary fixation strength can be obtained with this technique. The study was performed on calve knees. Full-thickness longitudinal tears 2 cm in length and 3 mm medial from the periphery were created in corpora of medial menisci of 14 calves. After creating tears, menisci were divided into two equal groups. In Group 1, two vertical loop sutures 1 cm apart were placed using a Viper device. Whereas in Group 2, tears were repaired using "butterfly" sutures. The mean load to failure was 156.3 ± 13.1 and 186 ± 15.8 N in Group 1 and 2, respectively (p = 0.002). The fixation strength in Group 2 was significantly higher than in Group 1. We suggest that, using Viper device and all-inside "butterfly" suturing techniques, meniscal ruptures with appropriate locations can be repaired with higher primary fixation strength.

Biomechanical evaluation of arthroscopic all-inside meniscus repairs.

Viper is a new device for arthroscopically all-inside meniscal repairing. In previous studies about Viper device, procedures were not applied arthroscopically despite this device has been designed for arthroscopic application. In this study, we evaluated primary fixation strength of arthroscopically applied meniscal repair using Viper device to obtain better clinical relevance. Two centimeter in length meniscal tear 2-3 mm far from periferic edge of medial meniscus of 50 calves were created arthroscopically. The menisci were divided into five groups including 10 menisci in each. In group 1, tears were repaired by outside-in vertical loop suture technique with No: 0 PDS. Tears were fixed by all-inside vertical suture by using Viper device with No: 0 PDS in group 2. In meniscal implant groups, RapidLoc, H-Fix, and Clearfix were applied in groups 3,4, and 5, respectively. Primary fixation strength of repairing techniques were evaluated with bio-mechanical testing machine. Fixation strengths determined in groups 1 and 2 were detected as 145 +/- 13 and 136 +/- 33 N, respectively. There was no difference in pull-out strength between groups 1 and 2. Fixation strengths in these two groups were significantly higher compared to groups 3, 4, and 5. There was no significant difference between group 3 (33 +/- 6 N) and 5 (28 +/- 6 N) in terms of fixation strengths whereas fixation strengths of these two groups were significantly higher compared to group 4 (20 +/- 3 N) (P = 0.005, P = 0.018, respectively). All-inside vertical suture technique using Viper device revealed comparable primary fixation strength with outside-in vertical suture technique for meniscal repair. We suggest that the Viper device is safe and reliable for meniscal repair.

[Comparison of the pull-out strengths of three different screws in pedicular screw revisions: a biomechanical study]. / Pediküler vida revizyonlarinda üç farkli tip vidanin siyirma kuvvetlerinin karsilastirilmasi: Biyomekanik çalisma.

OBJECTIVES: We investigated the possible effects of three pedicular screws on axial pull-out strength in pedicular revision surgery. METHODS: Two study groups were formed from calf lumbar vertebrae. Initially, Alici pedicular screws with an outer diameter of 6.5 mm were applied (with or without tapping) to all the pedicles. All the pedicles were subjected to axial pull-out testing to induce pedicular insufficiency. Then, Alici pedicular screws with an outer diameter of 7 mm were applied to the left pedicles. The right pedicles in the two study groups were assigned to receive two different types of pedicular screws with an expandable (enlargeable) end, respectively. Axial pull-out testing was repeated in both groups and the results were compared with the initial pull-out strength values. RESULTS: In the first group, 65% and 64% of the initial pull-out strengths were obtained with 7-mm Alici pedicular screws and with expandable pedicular screws, for the left and right pedicles, respectively. The corresponding pull-out strengths in the other study group were 70% and 68.5% of the initial values, respectively. Tapping of the screw hole entrance resulted in a mean decrease of 13% in the pull-out strength compared to screw applications without tapping. CONCLUSION: Pedicular screw revisions using a 0.5 mm greater screw in diameter did not provide adequate screw-bone inter-face strength and pedicle filling. Similarly, expandable pedicular screws did not contribute to screw stability.