Instrumentation of the osteoporotic spine: biomechanical and clinical considerations

Ponnusamy, Karthikeyan; Iyer, Sravisht; Gupta, Gaurav; Khanna, Ajai

doi:10.1016/j.spinee.2010.09.024

Cited by 164 publications

(120 citation statements)

References 102 publications

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“…First, it would be beneficial to understand whether BMD assessed by this method can predict screw loosening after spondylodesis, because planning of the procedure depends on bone strength. 15 Second, most of the lumbar spine MDCT scans in patients with spine disease are performed without prior application of IV contrast medium. Therefore, the method should be analyzed without the influence of IV contrast medium.…”

mentioning

confidence: 99%

Bone Mineral Density Values Derived from Routine Lumbar Spine Multidetector Row CT Predict Osteoporotic Vertebral Fractures and Screw Loosening

Schwaiger¹,

Gersing²,

Baum

et al. 2014

American Journal of Neuroradiology

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mentioning

confidence: 99%

Bone Mineral Density Values Derived from Routine Lumbar Spine Multidetector Row CT Predict Osteoporotic Vertebral Fractures and Screw Loosening

Schwaiger¹,

Gersing²,

Baum

et al. 2014

American Journal of Neuroradiology

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“…Osteopenic and osteoporotic bone is often encountered when performing spine surgery, influencing not only fracture risk also hardware fixation (9,21 (24). This study used two densities of simulated bone in a pedicle screw pullout model with and without toggling and hubbing.…”

Section: Discussionmentioning

confidence: 99%

“…This procedure is broadly successful with low rates of screw loosening for standard screws (1-3) and increased rates for dynamic systems (4)(5)(6)(7). Screw loosening is a concern, with radiolucency around screws detrimental to fixation (8) and often warranting revision surgery (9).…”

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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“…Pedicle screw systems are currently the most common technique for the stabilization of the spine, which requires a stable fixation in the bone [4,5]. But a poor bone mineral density in osteoporotic patients can result in a screw loosening [6][7][8][9]. Lamina hook systems have the advantage that they are connected directly to the lamina, which may have the advantage of a minimized injury risk for neural structures.…”

Section: Introductionmentioning

confidence: 99%

A pedicle screw system and a lamina hook system provide similar primary and long-term stability: a biomechanical in vitro study with quasi-static and dynamic loading conditions

et al. 2016

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Purpose For the stabilization of the thoracolumbar spine area, various stabilization techniques have been developed in recent decades. The aim of these techniques is to immobilize the treated segment to repositioning or correct the spine and guaranty long-term stability to achieve a reliable fusion. The aim of this study was to simulate in an in vitro experiment the postoperative long-term situation in elderly osteoporotic patients to compare two different stabilization principles; a pedicle screw system and a lamina hook system. Methods Two comparable groups with respect to age and bone mineral density with each n = 6 fresh-frozen human, bi-segmental thoracolumbar spine specimens (T11-L1) were used. Antero-posterior and lateral radiographs were taken before the test, to assess the spinal status. Then the intact specimens were biomechanically characterized with pure moments in the three anatomical planes in different states in terms of range of motion and neutral zone. After implantation of either, a pedicle screw system or a lamina hook system, the primary stability was determined under the same conditions. Subsequently the specimens were cyclically loaded under complex loading, using a custommade set-up in a dynamic materials testing machine with increasing moments from 3 to 66 Nm until 100,000 cycles or until one of the three defined ''failure'' criteria was reached.(1) A failure of a bony structure. (2) Exceeding of the threefold ROM of the primary stability after implantation in flexion plus extension. (3) Reaching of the ROM based on the intact state before implantation both in flexion plus extension.Results The results showed that the ROM was strongly reduced after instrumentation similar for both implant systems in all motion planes. The highest stabilization was found in flexion/extension. During cyclic loading with increasing moments, the ROM increased continuously for both systems. The number of load cycles until one of the failure criteria was reached varied only slightly between the two groups. In the pedicle screw group 30,000 (median) loading cycles (range 5000-80,000) with a corresponding moment of 24 Nm (range 9-54) could be reached. In the lamina hook group 32,500 load cycles (range 20,000-45,000) could be achieved with a corresponding moment of 25.5 Nm (range 18-33). There was a slight trend that the pedicle screw system is influenced more by bone mineral density. Conclusion Both implant systems provide similar primary stability and similar long-term stability. In the pedicle screw group, there was a stronger correlation between bone mineral density and the reached number of load cycles.

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Instrumentation of the osteoporotic spine: biomechanical and clinical considerations

Cited by 164 publications

References 102 publications

Bone Mineral Density Values Derived from Routine Lumbar Spine Multidetector Row CT Predict Osteoporotic Vertebral Fractures and Screw Loosening

Bone Mineral Density Values Derived from Routine Lumbar Spine Multidetector Row CT Predict Osteoporotic Vertebral Fractures and Screw Loosening

The contribution of the cortical shell to pedicle screw fixation

A pedicle screw system and a lamina hook system provide similar primary and long-term stability: a biomechanical in vitro study with quasi-static and dynamic loading conditions

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