Biomechanical Fixation Properties of the Cortical Bone Trajectory in the Osteoporotic Lumbar Spine

Li, Huimin; Zhang, Ren‐Jie; Gao, Hai; Jia, Chong-Yu; Xing, Tao; Zhang, Jianxiang; Dong, Fulong; Shen, Cailiang

doi:10.1016/j.wneu.2018.07.253

Cited by 44 publications

(35 citation statements)

References 26 publications

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“…Another study using 37 specimens with a BMD of 0.684±0.197 g/ cm 2 reported a pullout strength of 0.524±0.311 kN [19]. In a study of Li et al [18], the screw sizes were 6.5×45 mm and 4.5×30 mm. In a study of Jacob et al [19], the screw size was 6×40 mm.…”

Section: Discussionmentioning

confidence: 96%

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Identification of Pedicle Screw Pullout Load Paths for Osteoporotic Vertebrae

et al. 2020

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Study Design: A biomechanical study.Purpose: To determine the actual load path and compare pullout strengths as a function of screw size used in revision surgeries using postmortem human subject specimens.Overview of Literature: Pedicle screw fixation has become the standard of care in the surgical management of spinal instability. However, pullout failures are widely observed in osteoporotic spines and treated by revision surgeries using a higher diameter screw, performing cement augmentation, or increasing the levels of fixation. While the peak forces to final pullout are reported, the actual load path to achieve the final force level is not available. Methods: Six osteoporotic lumbar spines (L2–L5) were instrumented with 5.5×40 mm polyaxial screws and loaded along the axis of the screw using a material testing machine according to American Society for Testing of Materials 543-07 test protocol. Tests were again conducted by replacing them with 6.5×40 mm (group A) or 7.5×40 mm (group B) screws. Force-displacement data were grouped and load paths (mean±1 standard deviation) were compared.Results: Pullout strength decreased by 36% when the size of the revision screw was increased by 1 mm, while it increased by 35% when the size of the revision screw was increased by 2 mm compared to the index screw value. While the morphologies of the load paths were similar in all cases, they differ between the two groups: the larger screw responded with generally elevated stiffer path than the smaller screw, suggesting that revision surgery using a larger screw has more purchase along the inserted body-pedicle axis.Conclusions: A larger screw enhances strength and increases biomechanical stability in revision surgeries, although the final surgical decision is made by the clinician, which includes the patient’s anatomy and associated characteristics.

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Section: Discussionmentioning

confidence: 96%

“…The mean pullout strengths of 0.379±0.272 kN from this study are similar to those in the literature. In a study using 21 specimens with a mean BMD of 0.567±0.101 g/cm 2 , the pullout strength was 0.241±0.174 kN [18]. Another study using 37 specimens with a BMD of 0.684±0.197 g/ cm 2 reported a pullout strength of 0.524±0.311 kN [19].…”

Section: Discussionmentioning

confidence: 98%

Identification of Pedicle Screw Pullout Load Paths for Osteoporotic Vertebrae

et al. 2020

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“… [21] Many studies also reported the biomechanical advantages of lumbar arthrodesis of CBT screws especially in osteoporotic bone. [22] However, the S1 loosening problem may occur in CBT screw placement. To date, the large variation in CBT screw-loosening rate ranging from 0% to 62.5% must also be validated because of the limitation in cohort size and different evaluated methods.…”

Section: Discussionmentioning

confidence: 99%

Level-based analysis of screw loosening with cortical bone trajectory screws in patients with lumbar degenerative disease

Chen

Huang³

et al. 2020

Medicine

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This study aimed to verify the relationship between the number of fusion level and the risk of screw loosening by using cortical bone trajectory (CBT) screws in patients with lumbar degenerative disease. We retrospectively reviewed the serial plain radiograph images of lumbar degenerative disease patients who had undergone posterior fixation and fusion surgery with CBT from 2014. All included patients should have been followed-up with computed tomography scan or plain radiograph for at least 6 months after operation. We individually evaluated the prevalence of screw loosening according to each vertebral level. We also determined whether the number of screw fixation affected the prevalence of screw loosening and whether S1 fixation increased the risk of screw loosening. The screw-loosening rates were high at the S1 level. Moreover, although fixation involved to S1, the loosening rates evidently increased (Fisher exact test, P = .002 ∗∗ ). The screw-loosening rate was 6.56% in 2 level fusion. However, it increased with the number of fusion levels (3 level: 25.00%, 4 level: 51.16%, and 5 level: 62.50%). To investigate if the number of fusion level affected the S1 screw loosening, we classified the cohort of patients into either involving S1 (S1+ group) or not (S1– group) according to different fusion levels (Table 3 ). The screw loosening between 2 group in 2 (5.56% vs 6.98%) and 3 fusion level (26.32% vs 22.73%) did not exhibit any significant difference. Interestingly, significantly high screw loosening was found in 4 fusion level (60.00% vs 15.38%), indicating that the higher fusion level (4 level) can directly increase the risk of S1 screw loosening. Our data confirmed that the screw-loosening rate increases rate when long segment CBT fixation involves to S1. Therefore, in case of long-segment fixation by using CBT screw, surgeons should be aware of the fusion level of S1.

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“…Clinical e cacy was observed and showed that by applying this innovative technique, the intensity of xation in the lumbosacral or osteotomy region was improved, the risk of internal xation system breakage and the incidence of pseudarthrosis in the lumbosacral region was decreased [33], and distal muscle dissection and intraoperative bleeding were reduced [34]. This was especially true for patients with osteoporosis, who had better cortical bone screw control and lower orthopaedic loss rates [33][34]. Furthermore, complications associated with the sacral 2 ilium or ilium screw technique were also reduced [35].…”

Section: Discussionmentioning

confidence: 99%

Lumbosacral fusion terminated to S1 for adult degenerative scoliosis: Technical innovation and finite element analysis

Zhao

Guo

et al. 2020

Preprint

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Background: To evaluated the practicability and reliability of CBT+TT in the treatment of ADS by finite element analysis and the comparison of clinical effects.Methods: 18 cases were enrolled from patients who were admitted to the department of Spine Surgery in Affiliated Hospital of Qingdao University with a strict standard which qualify for the surgical indications of L5-S1 long segment fusion. Based on different spinal-pelvic fusion techniques, those cases were divided into three groups including the groups of IS , S2AI and CBT+TT, 3, 4 and 11 cases recpectively. Clinical data of CBT+TT group such as VAS, ODI, coronal Codd angle, C7PL-CSVL and SVA were acquired preoperatively and compared with those measured at the end of follow-up. DICOM data of CT scan (1mm) of all postoperative patients in those 3 groups were used to created 3D models. The models were imported into software for the finite element analysis under different conditions such as flexion, extension, lateral flexion and rotation, to obtain the stress distribution properties of three fusion techniques.Results: In CBT+TT group, the VAS score was 7.00±0.89 preoperatively and 0.91±0.70 at the end of follow-up. The ODI was 51.09±7.83% and 5.45±1.13%. There was a significant difference between the preoperative data and that at the end of follow-up (P<0.001). The Cobb angle was 49.10±11.51° and 12.33±3.96°. C7PL-CSVL was 27.27±17.61 mm and 12.20±8.04 mm. SVA was 25.33±18.21 mm and 8.60±5.31 mm. The results of the finite element analysis of simulated conditions, such as flexion, extension, lateral flexion and rotation, showed that in the IS group, the average extreme pressure value was 366.1 MPa, 183.1 MPa, 398.4 MPa, and 573.6 MPa; in the S2AI group, the values were 518.4 MPa, 259.2 MPa, 608.2 MPa, and 545.7 MPa; and in the CBT+TT group, the values were 390.0 MPa, 195.0 MPa, 353.7 MPa, and 476.8 MPa. Conclusion: This innovative technique (CBT+TT, terminating at S1) has been proven to be reliable and practical in the treatment of degenerative scoliosis.

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Biomechanical Fixation Properties of the Cortical Bone Trajectory in the Osteoporotic Lumbar Spine

Cited by 44 publications

References 26 publications

Identification of Pedicle Screw Pullout Load Paths for Osteoporotic Vertebrae

Identification of Pedicle Screw Pullout Load Paths for Osteoporotic Vertebrae

Level-based analysis of screw loosening with cortical bone trajectory screws in patients with lumbar degenerative disease

Lumbosacral fusion terminated to S1 for adult degenerative scoliosis: Technical innovation and finite element analysis

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