Estimation of pedicle screw fixation strength from probe indentation force and screw insertion torque: A biomechanical study on bone surrogates of various densities

Pedicle screws have been widely used for the treatment of spinal diseases, but improper screw placement is not uncommon and may lead to neurovascular injuries and reduced screw fixation strength. This study aimed to investigate the feasibility of using real-time screw insertion torque monitoring to prevent screw penetration. Commercially available synthetic L4 vertebrae were divided in to seven test groups based on different screw placements. Screw insertion torque and maximal pullout strength were compared among groups. The results indicated that the insertion torque gradually increased when the screw tip was within vertebral cancellous bone without penetration. However, an instantaneous decrease of torque value was observed once the screw tip penetrated the cortex wall. When compared to the control group, higher pullout strength was found for the groups with medial cortex penetration. However, vertebrae with medial cortex penetration may lead to the concern of neurovascular damage. Meanwhile, lower pullout strength was found for the groups with lateral cortex penetration and end-plate penetration, which may lead to the concern of screw loosening. We concluded that pedicle screw penetration can be judged using real-time screw insertion torque monitoring during surgery, which may aid surgeons in avoiding neurovascular injury and reduction of screw fixation strength.

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Pedicle Screw Fixation of the Thoracic Spine: An In Vitro Biomechanical Study on Different Configurations

Spine ◽

10.1097/01.brs.0000186590.45675.ce ◽

2005 ◽

Vol 30 (22) ◽

pp. 2530-2537 ◽

Cited By ~ 29

Author(s):

Vedat Deviren ◽

Emre Acaroglu ◽

Joe Lee ◽

Masaru Fujita ◽

Serena Hu ◽

...

Keyword(s):

Pedicle Screw ◽

Thoracic Spine ◽

Screw Fixation ◽

Pedicle Screw Fixation ◽

Biomechanical Study

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The Correlation between Insertion Torque of Pedicle Screws with Bone Mineral Density Values in Posterior Lumbar Pedicle Screw Fixation

The Spine Journal ◽

10.1016/j.spinee.2011.08.352 ◽

2011 ◽

Vol 11 (10) ◽

pp. S145-S146 ◽

Cited By ~ 2

Author(s):

Jae Hyup Lee ◽

Jae-Woo Park ◽

Ji-Ho Lee ◽

Hye Soo Lee

Keyword(s):

Bone Mineral Density ◽

Pedicle Screw ◽

Bone Mineral ◽

Screw Fixation ◽

Pedicle Screws ◽

Pedicle Screw Fixation ◽

Insertion Torque ◽

Mineral Density ◽

Density Values ◽

Lumbar Pedicle

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Biomechanical study of expandable pedicle screw fixation in severe osteoporotic bone comparing with conventional and cement-augmented pedicle screws

Medical Engineering & Physics ◽

10.1016/j.medengphy.2014.05.003 ◽

2014 ◽

Vol 36 (11) ◽

pp. 1416-1420 ◽

Cited By ~ 27

Author(s):

Yi-Long Chen ◽

Wen-Chuan Chen ◽

Chi-Wei Chou ◽

Jou-Wen Chen ◽

Chia-Ming Chang ◽

...

Keyword(s):

Pedicle Screw ◽

Screw Fixation ◽

Pedicle Screws ◽

Pedicle Screw Fixation ◽

Biomechanical Study ◽

Osteoporotic Bone

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Predictive Ability of Tapping Insertional Torque on Pedicle Screw Fixation Strength and Optimal Screw Size

The Spine Journal ◽

10.1016/j.spinee.2011.08.384 ◽

2011 ◽

Vol 11 (10) ◽

pp. S160-S161

Author(s):

Melvin Helgeson ◽

Ronald Lehman ◽

Anton Dmitriev ◽

Daniel Kang ◽

Scott Luhmann

Keyword(s):

Pedicle Screw ◽

Screw Fixation ◽

Predictive Ability ◽

Pedicle Screw Fixation ◽

Fixation Strength ◽

Insertional Torque

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Short segment pedicle screw fixation of thoracolumbar fracture: a case series of 33 patients

International Journal of Research in Orthopaedics ◽

10.18203/issn.2455-4510.intjresorthop20172550 ◽

2017 ◽

Vol 3 (4) ◽

pp. 681

Author(s):

Naushad Hussain ◽

Nirmal Dhananjay Patil ◽

Hiren Patel ◽

Akash Shakya

Keyword(s):

Pedicle Screw ◽

Screw Fixation ◽

Wedge Angle ◽

Body Height ◽

Pedicle Screw Fixation ◽

Thoracolumbar Fracture ◽

Vertebral Body Height ◽

Short Segment ◽

Screw Insertion

Background: Pedicle screw instrumentation in case of fracture spine provides stable fixation. However in absence of experience and proper technique of pedicle screw insertion, it is associated with many complications. We aim to study the results of patients with thoracolumbar fracture stabilized with short segment pedicle screw instrumentation.Methods: 33 cases of thoracolumbar wedge compression fracture spine presenting to Nair Hospital were included in the study. All patients were operated by the senior author via a posterior approach and short segment pedicle screw fixation. Patients were followed up for one year.Results: 33 patients with a mean age were 37.6 years of which 3 were females and 30 were males in our study. Fall from height (93.93%) was the most common mode of injury followed by road traffic accident (6.07%). D12 and L1 were the most common vertebrae involved. Statistically significant (p=0.01) correction in the vertebral body height occurred in the immediate postop period and there was 4.1% loss of correction at final follow-up. There was statistically significant improvements in the Regional angle (p=0.03) and anterior wedge angle (p=0.03). Residual regional angle at final follow-up was found to be >5° in 3 patients. Neurological improvement was seen in 23 (74.19%) patients (p=0.01). No improvements were seen in 8 (25.81%) patients. None of our patients had postoperative worsening of the neurological status. None of the patients had pedicle wall breach on final follow up CT scan.Conclusions: Short segment fixation in case of wedge fracture can restore the vertebral body height, mean regional angle and mean anterior wedge angle and provide good outcome. There are poor chances of recovery of patient with Frankel grade A. Meticulous dissection and careful technique of pedicle screw insertion, adequate decompression, good contouring of the rod with correction of kyphosis can provide excellent results.

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Effects of different pedicle screw insertion depths on sagittal balance of lumbar degenerative spondylolisthesis, a retrospective comparative study

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04736-1 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Quan Zhou ◽

Jun-xin Zhang ◽

Yi-fei Zheng ◽

Yun Teng ◽

Hui-lin Yang ◽

...

Keyword(s):

Pedicle Screw ◽

Sagittal Balance ◽

Screw Fixation ◽

Degenerative Spondylolisthesis ◽

Leading Edge ◽

Pedicle Screw Fixation ◽

Screw Insertion ◽

Lumbar Degenerative Spondylolisthesis ◽

Screw Group

Abstract Background Few reports to date have evaluated the effects of different pedicle screw insertion depths on sagittal balance and prognosis after posterior lumbar interbody and fusion (PLIF) in patients with lumbar degenerative spondylolisthesis (LDS). Methods A total of 88 patients with single-level PLIF for LDS from January 2018 to December 2019 were enrolled. Long screw group (Group L): 52 patients underwent long pedicle screw fixation (the leading edge of the screw exceeded 80% of the anteroposterior diameter of vertebral body). Short screw group (Group S): 36 patients underwent short pedicle screw fixation (the leading edge of the screw was less than 60% of the anteroposterior diameter of vertebral body). Local deformity parameters of spondylolisthesis including slip degree (SD) and segment lordosis (SL), spino-pelvic sagittal plane parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and lumbar lordosis (LL), Oswestry Disability Index (ODI), and Visual Analog Scale (VAS) for back pain of both groups were compared. Postoperative complications, including vertebral fusion rate and screw loosening rate, were recorded. Results Except that PI in Group S at the final follow-up was not statistically different from the preoperative value (P > 0.05), other parameters were significantly improved compared with preoperative values one month after surgery and at the final follow-up (P < 0.05). There was no significant difference in parameters between Group L and Group S before and one month after surgery (P > 0.05). At the final follow-up, SD, SL, LL, PT and PI-LL differed significantly between the two groups (P < 0.05). Compared with the preoperative results, ODI and VAS in both groups decreased significantly one month after surgery and at the final follow-up (P < 0.05). Significant differences of ODI and VAS were found between the two groups at the final follow-up (P < 0.05). Postoperative complications were not statistically significant between the two groups (P > 0.05). Conclusions PLIF can significantly improve the prognosis of patients with LDS. In terms of outcomes with an average follow-up time of 2 years, the deeper the screw depth is within the safe range, the better the spino-pelvic sagittal balance may be restored and the better the quality of life may be.

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