Effect of Physiological Loads on Cortical and Traditional Pedicle Screw Fixation

Baluch, Daniel A.; Patel, Alpesh A.; Lullo, Brett; Havey, Robert M.; Voronov, Leonard I.; Nguyễn, Ngọc Tuấn; Carandang, Gerard; Ghanayem, Alexander J.; Patwardhan, Avinash G.

doi:10.1097/brs.0000000000000553

Cited by 134 publications

(116 citation statements)

References 29 publications

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“…1,8 Some researchers have reported that CBT screw-rod fixation provided about the same stability as traditional PS-rod fixation, regardless of the presence of interbody support. 8 Others have reported that a CBT screw-rod construct has significantly superior resistance to craniocaudal toggling displacement compared with a traditional PS-rod construct.…”

Section: Discussionmentioning

confidence: 99%

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Posterior lumbar interbody fusion with cortical bone trajectory screw fixation versus posterior lumbar interbody fusion using traditional pedicle screw fixation for degenerative lumbar spondylolisthesis: a comparative study

Sakaura

Miwa

Yamashita

et al. 2016

SPI

104

102

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OBJECTIVE Several biomechanical studies have demonstrated the favorable mechanical properties of the cortical bone trajectory (CBT) screw. However, no reports have examined surgical outcomes of posterior lumbar interbody fusion (PLIF) with CBT screw fixation for degenerative spondylolisthesis (DS) compared with those after PLIF using traditional pedicle screw (PS) fixation. The purposes of this study were thus to elucidate surgical outcomes after PLIF with CBT screw fixation for DS and to compare these results with those after PLIF using traditional PS fixation. METHODS Ninety-five consecutive patients underwent PLIF with CBT screw fixation for DS (CBT group; mean followup 35 months). A historical control group consisted of 82 consecutive patients who underwent PLIF with traditional PS fixation (PS group; mean follow-up 40 months). Clinical status was assessed using the Japanese Orthopaedic Association (JOA) scale score. Fusion status was assessed by dynamic plain radiographs and CT. The need for additional surgery and surgery-related complications was also evaluated. RESULTS The mean JOA score improved significantly from 13.7 points before surgery to 23.3 points at the latest follow-up in the CBT group (mean recovery rate 64.4%), compared with 14.4 points preoperatively to 22.7 points at final follow-up in the PS group (mean recovery rate 55.8%; p < 0.05). Solid spinal fusion was achieved in 84 patients from the CBT group (88.4%) and in 79 patients from the PS group (96.3%, p > 0.05). Symptomatic adjacent-segment disease developed in 3 patients from the CBT group (3.2%) compared with 9 patients from the PS group (11.0%, p < 0.05). CONCLUSIONS PLIF with CBT screw fixation for DS provided comparable improvement of clinical symptoms with PLIF using traditional PS fixation. However, the successful fusion rate tended to be lower in the CBT group than in the PS group, although the difference was not statistically significant between the 2 groups.

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Section: Discussionmentioning

confidence: 99%

“…1,8 In addition, screw insertion through a caudomedial starting point enables less invasive posterior lumbar fixation by limiting dissection of the superior facet joints and reducing muscle dissection and retraction. Our cephalad screw trajectory follows a mediolateral-and caudocephalad-directed path according to the original method.…”

mentioning

confidence: 99%

Posterior lumbar interbody fusion with cortical bone trajectory screw fixation versus posterior lumbar interbody fusion using traditional pedicle screw fixation for degenerative lumbar spondylolisthesis: a comparative study

Sakaura

Miwa

Yamashita

et al. 2016

SPI

104

102

View full text Add to dashboard Cite

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“…Several studies have investigated factors influencing pedicle screw stability, such as trajectory (25,26), hole preparation (27), reuse of pilot holes (28) and screw back out (29). The removal of the cortex immediately surrounding the pedicle screw simulates a variation on screw placement known as hubbing.…”

Section: Discussionmentioning

confidence: 99%

“…Screw pull-out studies using human cadaveric tissues report a wide range of values from 102 to 1,741 N (15,26,28,(31)(32)(33)(34). Similarly, screw pull-out with the calf model reports values from 747 to 7,300 N, depending on treatment (30,35).…”

Section: Comparison To Existing Literaturementioning

confidence: 99%

The contribution of the cortical shell to pedicle screw fixation

Pelletier¹,

Bertollo²,

Al-Khawaja³

et al. 2017

J. Spine Surg.

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Background: A pedicle screw insertion technique known as "hubbing" involves the removal of cortical bone around the screw insertion with the aim of improving fixation and decreasing screw loosening.However, the efficacy of this procedure relative to bone density and early loading have not been fully explored. The purpose of this study is to establish the contribution of the cortical layer (hubbing), cancellous density, early loading (toggling) in an idealised model. This is an in vitro laboratory study.Methods: Synthetic bone blocks with cancellous bulk and a simulated cortical shell were implanted with 6.5 mm pedicle screws. Three key variables were evaluated in this study; density of the simulated bone (10-20 lb/ft 3 ), toggling (±0.5 mm for 10,000 cycles), and the presence or absence of the surrounding cortex (hubbing). Pullout testing after toggling was performed to determine maximum load, stiffness and energy.Results were analyzed to assess interaction and main effects.Results: Removal of the cortex decreased the pullout loads by approximately 1,100 N after toggling.Toggling in the presence of the cortical shell had no effect. However, once the cortical shell is removed damage to the weaker cancellous bone accumulates and further compromises the fixation.Conclusions: The addition of a cortical layer in the Sawbone model is significant and provides a more realistic model of load sharing. The cortex plays a considerable role in the protection of underlying cancellous bone as well as contributing to initial pullout strength. The results of this study demonstrate a negative synergistic effect when both toggling and hubbing are applied to the weaker bone.

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“…In their report, CBT screws (average 4.5-mm diameter and 29-mm length) demonstrated a 30% greater uniaxial pullout strength and equivalent strength against toggle loading as compared to TT screws (average 6.5-mm diameter and 51-mm length) ( Table 1). More practically replicating a mechanism of pedicle screw loosening, Baluch et al compared the fixation strength of CBT screws (average 4.5-mm diameter and 32-mm length) with that of TT screws (average 6.5-mm diameter and 45-mm length) under cyclic loads perpendicular to the screw axis, and demonstrated the superior resistance of CBT screws 23) . Another study also evaluated the mechanical behavior of CBT screws in vivo by measuring insertional torque 24) .…”

Section: Fixation Strength Of Cbt Screwmentioning

confidence: 99%

Lumbar pedicle screw fixation with cortical bone trajectory: A review from anatomical and biomechanical standpoints

Matsukawa

Yato

2017

Spine Surg Relat Res

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Abstract:Over the past few decades, many attempts to enhance the integrity of the bone-screw interface have been made to prevent pedicle screw failure and to achieve a better clinical outcome when treating a variety of spinal disorders. Cortical bone trajectory (CBT) has been developed as an alternative to the traditional lumbar pedicle screw trajectory. Contrary to the traditional trajectory, which follows the anatomical axis of the pedicle from a lateral starting point, CBT starts at the lateral part of the pars interarticularis and follows a mediolateral and caudocranial screw path through the pedicle. By markedly altering the screw path, CBT has the advantage of achieving a higher level of thread contact with the cortical bone from the dorsal entry point to the vertebral body. Biomechanical studies demonstrated the superior anchoring ability of CBT over the traditional trajectory, even with a shorter and smaller CBT screw. Furthermore, screw insertion from a more medial and caudal starting point requires less exposure and minimizes the procedure-related morbidity, such as reducing damage to the paraspinal muscles, avoiding iatrogenic injury to the cranial facet joint, and maintaining neurovascular supply to the fused segment. Thus, the features of CBT, which enhance screw fixation with limited surgical exposure, have attracted the interest of surgeons as a new minimally invasive method for spinal fusion.The purpose of this study was: 1) to identify the features of the CBT technique by reviewing previous anatomical and biomechanical literature, and 2) to describe its clinical application with a focus on the indications, limitations, surgical technique, and clinical evidence.

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Effect of Physiological Loads on Cortical and Traditional Pedicle Screw Fixation

Abstract: N/A.

Cited by 134 publications

References 29 publications

Posterior lumbar interbody fusion with cortical bone trajectory screw fixation versus posterior lumbar interbody fusion using traditional pedicle screw fixation for degenerative lumbar spondylolisthesis: a comparative study

Posterior lumbar interbody fusion with cortical bone trajectory screw fixation versus posterior lumbar interbody fusion using traditional pedicle screw fixation for degenerative lumbar spondylolisthesis: a comparative study

The contribution of the cortical shell to pedicle screw fixation

Lumbar pedicle screw fixation with cortical bone trajectory: A review from anatomical and biomechanical standpoints

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