A comparative study on screw loosening in osteoporotic lumbar spine fusion between expandable and conventional pedicle screws

Wu, Zixiang; Gong, Futai; Liu, Li; Ma, Zhen; Zhang, Yang; Xiong, Zhi‐Gang; Yang, Min; Lei, Wei; Sang, Hongxun

doi:10.1007/s00402-011-1439-6

Cited by 148 publications

(114 citation statements)

References 25 publications

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“…In previous clinical series, sacroiliac screw loosening was approximately 10% in mixed populations [31,32]. As known from spine surgery, the risk of screw loosening in patients with osteoporosis can be as much as 25% [30,47]. Thus, the presence of osteoporosis was estimated to double the rate of screw loosening, therefore we set the clinically relevant effect size in this model of osteoporosis as cement resulting in halving of the amount of screw migration.…”

Section: Discussionmentioning

confidence: 99%

“…In patients with osteoporotic bone, however, loosening of the screws frequently is seen [15,30,47]. This is a dynamic process and failure to achieve stable anchorage in sacroiliac screw fixation can result in loosening of the screws, but equally important can be the long-lasting immobilization resulting from pain in patients who are already-frail and deconditioned.…”

Section: Introductionmentioning

confidence: 99%

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Cement Augmentation in Sacroiliac Screw Fixation Offers Modest Biomechanical Advantages in a Cadaver Model

Osterhoff

Dodd

Unno

et al. 2016

Clinical Orthopaedics &Amp; Related Research

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Background Sacroiliac screw fixation in elderly patients with pelvic fractures is prone to failure owing to impaired bone quality. Cement augmentation has been proposed as a possible solution, because in other anatomic areas this has been shown to reduce screw loosening. However, to our knowledge, this has not been evaluated for sacroiliac screws. Questions/purposes We investigated the potential biomechanical benefit of cement augmentation of sacroiliac screw fixation in a cadaver model of osteoporotic bone, specifically with respect to screw loosening, construct survival, and fracture-site motion. Methods Standardized complete sacral ala fractures with intact posterior ligaments in combination with ipsilateral upper and lower pubic rami fractures were created in osteoporotic cadaver pelves and stabilized by three fixation techniques: sacroiliac (n = 5) with sacroiliac screws in S1 and S2, cemented (n = 5) with addition of cement augmentation, and transsacral (n = 5) with a single transsacral screw in S1. A cyclic loading protocol was applied with torque (1.5 Nm) and increasing axial force (250-750 N). Screw loosening, construct survival, and sacral fracture-site motion were measured by optoelectric motion tracking. A sample-size calculation revealed five samples per group to be required to achieve a power of 0.80 to detect 50% reduction in screw loosening. Results Screw motion in relation to the sacrum during loading with 250 N/1.5 Nm was not different among the three groups (sacroiliac: 1.2 mm, range, 0.6-1.9; cemented: 0.7 mm, range, 0.5-1.3; transsacral: 1.1 mm, range, 0.6-2.3) (p = 0.940). Screw subsidence was less in the cemented group (3.0 mm, range, 1.2-3.7) compared with the sacroiliac (5.7 mm, range, 4.7-10

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cement Augmentation in Sacroiliac Screw Fixation Offers Modest Biomechanical Advantages in a Cadaver Model

Osterhoff

Dodd

Unno

et al. 2016

Clinical Orthopaedics &Amp; Related Research

View full text Add to dashboard Cite

show abstract

“…New concepts range from alternative fixations options such as transfacet screws or lamina hooks [10,11] to expandable or modified pedicle screws [12,13] and to bone cements with modified, more physiological mechanical properties [14,15]. For conventional pedicle screws, various augmentation techniques and augmentation materials to prevent screw loosening are available [16].…”

Section: Discussionmentioning

confidence: 99%

Timing of PMMA cement application for pedicle screw augmentation affects screw anchorage

et al. 2017

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Introduction Cement augmentation is an established method to increase the pedicle screw (PS) anchorage in osteoporotic vertebral bodies. The ideal timing for augmentation when a reposition maneuver is necessary is controversial. While augmentation of the PS before reposition maneuver may increase the force applied it on the vertebrae, it bears the risk to impair PS anchorage, whereas augmenting the PS after the maneuver may restore this anchorage and prevent early screw loosening. The purpose of the present study was to evaluate the effect of cement application timing on PS anchorage in the osteoporotic vertebral body. Methods Ten lumbar vertebrae (L1-L5) were used for testing. The left and right pedicles of each vertebra were instrumented with the same PS size and used for pairwise comparison of the two timing points for augmentation. For the reposition maneuver, the left PS was loaded axially under displacement control (2 9 ±2 mm, 3 9 ±6 mm, 3 9 ±10 mm) to simulate a reposition maneuver.Subsequently, both PS were augmented with 2 ml PMMA cement. The same force as measured during the left PS maneuver was applied to the previously augmented right hand side PS [2 9 F (±2 mm), 3 9 F (±6 mm), 3 9 F (±10 mm)]. Both PS were cyclically loaded with initial forces of ?50 and -50 N, while the lower force was increased by 5 N every 100 cycles until total failure of the PS. The PS motion was measured with a 3D motion analysis system. After cyclic loading stress, X-rays were taken to identify the PS loosening mechanism. Results In comparison with PS augmented prior to the reposition maneuver, PS augmented after the reposition maneuver showed a significant higher number of load cycles until failure (5930 ± 1899 vs 3830 ± 1706, p = 0.015). The predominant loosening mechanism for PS augmented after the reposition maneuver was PS toggling with the attached cement cloud within the trabecular bone. While PS augmented prior to the reposition, maneuver showed a motion of the screw within the cement cloud. Conclusion The time of cement application has an effect on PS anchorage in the osteoporotic vertebral body if a reposition maneuver of the instrumented vertebrae is carried out. PS augmented after the reposition maneuver showed a significant higher number of load cycles until screw loosening.

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“…However, it is unknown if an alteration in BMD can predispose bone to toggling damage following hubbing. Screw loosening has been shown to be more common in osteoporotic patients (19). The majority of screw stability is attained through fixation with cortical bone which suggests that hubbing may pose a greater risk to these patients (20).…”

Section: Introductionmentioning

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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A comparative study on screw loosening in osteoporotic lumbar spine fusion between expandable and conventional pedicle screws

Abstract: EPS can decrease the risk of screw loosening and achieve better fixation strength and clinical results in osteoporotic lumbar spine fusion.

Cited by 148 publications

References 25 publications

Cement Augmentation in Sacroiliac Screw Fixation Offers Modest Biomechanical Advantages in a Cadaver Model

Cement Augmentation in Sacroiliac Screw Fixation Offers Modest Biomechanical Advantages in a Cadaver Model

Timing of PMMA cement application for pedicle screw augmentation affects screw anchorage

The contribution of the cortical shell to pedicle screw fixation

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