====== Polyetheretherketone rod ======

{{ ::polyetheretherketone_rods.jpg?250|}}

[[Polyetheretherketone]] [[rod]] provides excellent chemical resistance, very low moisture absorption, and high wear resistance, and it is unaffected by continuous exposure to hot water or steam. 
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Polyetheretherketone (PEEK) rods have become available as an alternative to metal rods for use with pedicle screws to perform the [[posterior lumbar fusion]]. PEEK has a modulus of elasticity between that of cortical and cancellous bones, thus mimicking the features of the physiological environment
((Ponnappan RK, Serhan H, Zarda B, Patel R, Albert T, Vaccaro AR. Biomechanical evaluation and comparison of polyetheretherketone rod system to traditional titanium rod fixation. Spine J. 2009;9(3):263–267.))
((Highsmith JM, Tumialan LM, Rodts GE., Jr Flexible rods and the case for dynamic stabilization. Neurosurg Focus. 2007;22(1):E11.))
((Cavagna R, Tournier C, Aunoble S, Bouler JM, Antonietti P, Ronai M, et al. Lumbar decompression and fusion in elderly osteoporotic patients: a prospective study using less rigid titanium rod fixation. J. Spinal Disord Tech. 2008;21(2):86–91.)).
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Furthermore, PEEK is translucent to X-rays, so these rods cause fewer artifacts on computed tomography scans making radiologic follow-up easier
((Sarbello JF, Lipman AJ, Hong J, et al. Patient perception of outcomes following failed spinal instrumentation with polyetheretherketone rods and titanium rods. Spine. 2010 Aug 1;35(17):E843–E848.)).
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Experience with PEEK rod systems has shown satisfactory clinical outcomes. Therefore, these results support the use of PEEK rod systems as supplemental fixation during lumbar fusion procedures.
((Selim A, Mercer S, Tang F. Polyetheretherketone (PEEK) Rods for Lumbar Fusion: A Systematic Review and Meta-Analysis. Int J Spine Surg. 2018 Aug 3;12(2):190-200. doi: 10.14444/5027. PMID: 30276079; PMCID: PMC6159719.))
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Posterior [[stabilization]] with [[PEEK]] rods is less [[invasive]] and was associated with significantly lower [[blood loss]], administration of blood products, and shorter operation time. Moreover, in patients above 80 years of age [[reoperation]]s rates were lower with PEEK rods, as well. Nevertheless, the benefits of PEEK rods for [[foraminal stenosis]] still have to be investigated
((Kamenova M, Li E, Soleman J, Fiebig O, Mehrkens A, Schaeren S. Posterior stabilization with polyetheretherketone (PEEK) rods and transforaminal lumbar interbody fusion (TLIF) with titanium rods for single-level lumbar spine degenerative disease in patients above 70 years of age. Arch Orthop Trauma Surg. 2022 May 5. doi: 10.1007/s00402-022-04448-8. Epub ahead of print. PMID: 35511354.)).
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A multicenter study did not support the hypothesis that PEEK rods are associated with a lower [[adjacent segment disease]] risk. Reasons for [[readmission]] need to be identified to better understand the differences observed here. Further study of patients with [[TLIF]] using Ti and PEEK rods and posterolateral fusion with Ti and PEEK rods is needed
((Hirt D, Prentice HA, Harris JE, Paxton EW, Alexander J, Nagasawa DT, Khosla D, Kurtz SM. Do PEEK Rods for Posterior Instrumented Fusion in the Lumbar Spine Reduce the Risk of Adjacent Segment Disease? Int J Spine Surg. 2021 Apr;15(2):251-258. doi: 10.14444/8034. PMID: 33900982; PMCID: PMC8059379.)).
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The widespread use of [[instrumentation]] in the [[lumbar spine]] has led to high rates of [[fusion]]. This has been accompanied by a marked rise in [[adjacent segment disease]], which is considered to be an increasingly common and significant consequence of lumbar or lumbosacral fusion. Numerous biomechanical studies have demonstrated that segments fused with rigid metallic fixation lead to significant amounts of supraphysiological stress on adjacent [[disc]]s and [[facet]]s. The resultant [[disc degeneration]] and/or [[stenosis]] may require further surgical intervention and extension of the fusion to address symptomatic adjacent-segment disease. [[Dynamic stabilization]] [[implant]]s and disc [[arthroplasty]] have been introduced as an alternative to rigid fixation. The scope of spinal disease that can be treated with this novel technology, however, remains limited, and these treatments may not apply to patients who still require rigid stabilization and [[arthrodesis]]. In the spectrum between rigid metallic fixation and motion-preserving arthroplasty is a semirigid type of stabilization in which a construct is used that more closely mirrors the modulus of elasticity of natural bone. After either interbody or posterolateral arthrodesis is achieved, the fused segments will not generate the same adjacent-level forces believed to be the cause of adjacent-segment disease. Although this form of arthrodesis does not completely prevent adjacent-segment disease, the dynamic component of this stabilization technique may minimize its occurrence. 
Highsmith reported their initial experience with the use of posterior dynamic stabilization in which [[polyetheretherketone]] rods were used for a posterior construct
((Highsmith JM, Tumialán LM, Rodts GE Jr. Flexible rods and the case for dynamic
stabilization. Neurosurg Focus. 2007 Jan 15;22(1):E11. PubMed PMID: 17608332.
)).
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PEEK rods demonstrate a similar fusion and reoperation rate in comparison to other instrumentation modalities in the treatment of degenerative lumbar spine disease
((Ormond DR, Albert L Jr, Das K. Polyetheretherketone (PEEK) Rods in Lumbar
Spine Degenerative Disease: A Case Series. Clin Spine Surg. 2016
Aug;29(7):E371-5. doi: 10.1097/BSD.0b013e318277cb9b. PubMed PMID: 23075859.
)).