|Year : 2019 | Volume
| Issue : 2 | Page : 29-33
Polyetheretherketone cages used in anterior cervical discectomy and fusion surgery: a meta-analysis
Sukrit Sharma1, Shakti Amar Goel2, Sunil Sharma2, Harvinder Singh Chhabra2
1 Amity University, Noida, India
2 Indian Spinal Injuries Centre, Vasant kunj, New Delhi, India
|Date of Submission||03-Feb-2019|
|Date of Acceptance||13-Apr-2019|
|Date of Web Publication||7-Jun-2019|
Harvinder Singh Chhabra
Indian Spinal Injuries Centre, Vasant kunj, New Delhi
Source of Support: None, Conflict of Interest: None
Background and objective: In the current clinical scenario, a wide variety of fusion techniques are being used along with polyetheretherketone (PEEK) cages in anterior cervical discectomy and fusion surgeries. Some of these techniques involve use of autografts, allografts, biomaterials or only PEEK cages. In this study, the existing literatures for anterior cervical discectomy fusion surgeries using PEEK cages and their outcomes have been reviewed to evaluate the results for the best possible alternative.
Materials and methods: A PubMed search for all papers stating “PEEK cages used in cervical spinal fusion,” “PEEK materials used in cervical spinal fusion,” and “artificial materials used in cervical fusion surgery with PEEK cages” was done for all studies before January 2018. A total of 197 studies were found, of which 15 were shortlisted as per the inclusion criteria. The existing literatures on PEEK cages used in spinal surgeries were reviewed and analyzed. Statistical analysis was done using SPSS software version 25.0 and Student’s t-test was used to compare the results.
Results: The total number of patients involved in the existing study was 767 with a mean age of 51.67 ± 9.01 years. 191 patients (24.9%) had cervical radiculopathy or myelopathy; 35 patients (4.5%) had cervical degenerative diseases; 29 patients (3.78%) had cervical spine injury with monosegmental instability; and the rest of the patients suffered from other disorders. The level of surgery for patients was single in 429 patients (55.93%) and multiple in 338 patients (44.06%). PEEK plus bone grafts had a significantly better fusion rate compared with PEEK plus artificial materials (95% confidence interval: 91.075 ± 2.09%; P = 0.0035) for multiple-level anterior cervical discectomy and fusion surgery.
Conclusion: PEEK plus bone grafts showed a significant fusion rate compared with PEEK plus artificial materials. PEEK plus bone grafts is a better filler material as compared to PEEK plus artificial materials in anterior cervical discectomy and fusion surgeries for multiple levels involved.
Keywords: cervical fusion surgeries; polyetheretherketone cage; bone graft; artificial material; anterior cervical discectomy fusion; interbody; spinal implant; meta-analysis
|How to cite this article:|
Sharma S, Goel SA, Sharma S, Chhabra HS. Polyetheretherketone cages used in anterior cervical discectomy and fusion surgery: a meta-analysis. Clin Trials Orthop Disord 2019;4:29-33
|How to cite this URL:|
Sharma S, Goel SA, Sharma S, Chhabra HS. Polyetheretherketone cages used in anterior cervical discectomy and fusion surgery: a meta-analysis. Clin Trials Orthop Disord [serial online] 2019 [cited 2019 Aug 25];4:29-33. Available from: http://www.clinicalto.com/text.asp?2019/4/2/29/259629
| Introduction|| |
Cervical radiculopathy is depicted as torment, or manifestation resulting in nerve aggravation, contributing to neurological disorders. Mechanical compression on the nerve of cervical locale, and release of inflammatory cytokines from damaged intervertebral discs can be a few reasons for the disorders’ induction., Due to degeneration or injury, the neck’s spinal trench may get limited and neurologic deficiencies occur, a condition broadly known as myelopathy. Anterior cervical discectomy and fusion surgeries are usually performed for such an ailment which involves removing damaged disc and relieving cord or nerve root pressure, and hence, alleviating pain, weakness, tingling. The surgery is approached through the front or anterior region of cervical neck or spine, followed by a fusion of the vertebra to stabilize the segment. Fusion may be obtained through bone grafts, implants, metal plates or cages.,,, Literature evidence has shown that various kinds of materials could be used for the structural integrity. Some of them include carbon fibres and titanium. These cage materials have been criticized on the basis of structural failure, instances of subsidence and migration issues. There are instances of more screw and cage related worries when dealing with titanium cages.,
Polyetheretherketone (PEEK) is a thermoplastic material with mechanical properties and chemical resistance. For the sake of improvement of their osteoinductive and antimicrobial capabilities, different types of functionalization of PEEK surfaces and changes in PEEK structure have been proposed., PEEK, hence, is becoming an important group of biomaterials used for bone and cartilage replacement as well as in a large number of diverse medical fields. Some of the properties of PEEK materials include resistance towards organic as well as aqueous environments. PEEK has shown low integration with the tissue of the bone because of its inert surface and low biocompatibility., To increase the fusion rates with PEEK cages, a number of filler materials are used such as autografts or allografts, biomaterials such as β-tricalcium phosphate, demineralised bone matrix or bone morphogenetic proteins. The purpose of this review is to analyze the existing literature on the use of PEEK cages in cervical fusion surgery and their radiological as well as functional outcomes.
| Data and Methods|| |
Search strategy and selection criteria
A PubMed search for papers stating “PEEK cages used in cervical spinal fusion,” “PEEK materials used in cervical spinal fusion,” and “artificial materials used in cervical fusion surgery with PEEK cages” was conducted for all studies before January 2018. This systematic review and meta-analysis was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. A total of 197 studies were found. Literatures on humans with full-text availability were selected for the review paper. Studies only in English were included. There were a few studies regarding “titanium cages vs. PEEK cages,” “subsidence over the use of PEEK,” but no reviews were present compiling the same. A total of 15 studies were shortlisted. Selection of articles was based on keywords such as “polyetheretherketone cage,” “cervical fusion surgeries,” “interbody” [Figure 1].
Data extraction and quality assessment
The authors have independently assessed the quality of each study selected for review. The data have been independently appraised from studies by utilizing a data extraction sheet. If the data were not available, the author would be contacted for information. Only the published parameters were noted in instances of non-contact with the author. Pooling of data was done, only when it was sensible to do so. Homogenous data, including study, levels, fusion rate, follow-up period, disorder, material and additional material, were pooled together. Two independent reviewers performed data extraction and quality assessment, with any disagreement resolved by discussion.
Statistical analysis was done using SPSS software version 25.0 (IBM Corp., Armonk, NY, USA). Student’s t-test was used to compare the results. The Student’s t-test determined statistical significance with a confidence interval of 95% when P ≤ 0.05 and significance level (*) was used as a pre-chosen probability and equaled 0.05.
| Results|| |
Number of patients and disorders
The total number of patients involved in this study was 767 with a mean age of 51.67 ± 9.01 years. 191 patients (24.9%) had cervical radiculopathy or myelopathy; 35 patients (4.5%) had cervical degenerative diseases; 29 patients (3.78%) had cervical spine injury with monosegmental instability; and the rest of the patients suffered from other disorders [Table 1].
Publication bias was ruled out by independent assessment by the authors.
Level of surgery and different filling materials used in patients
The level of surgery for patients was single in 429 patients (55.93%) and multiple in 338 patients (44.06%). PEEK plus bone grafts and PEEK plus artificial materials were used in 47.58% and 52.41% of the patients, respectively.
Fusion rates of PEEK plus bone grafts and PEEK plus artificial materials
PEEK plus bone grafts had a significantly better fusion rate compared with PEEK plus artificial materials (95% confidence interval: 91.075 ± 2.09%; P = 0.0035) for multi-level anterior cervical discectomy and fusion surgery [Table 2].
|Table 2: Filler materials in anterior cervical discectomy and fusion surgery with their fusion rates|
Click here to view
| Discussion|| |
PEEK has been widely used in anterior cervical discectomy fusion surgeries. However, the efficacy of PEEK with or without the filler material is unknown. Its use has been proven to be highly advantageous by virtue of its biochemical properties being similar to bone., PEEK is a semicrystalline, polyaromatic and linear polymer, which provides combination of strength, toughness as well as environmental resistance with properties such as biocompatibility, corrosion-resistance and non-absorbance.,, PEEK cage has also demonstrated absence of cytotoxicity and mutagenicity in an in-vitro setup. Its manufacturing can be stationed as per specifications with optimum interbody space, adequate volume for bone refilling and stability based on mechanical demand.,
Some of the merits of PEEK cage include satisfactory fusion rate, foraminal distraction and ease of radiographic evaluations making examinations easy. Anatomical shapes, allowance of nerve root decompression, and radiolucency are the other advantages.,,
The filling materials used in PEEK cages range from grafts which are autografts or allografts and artificial materials. The use of empty cages has also been reported in anterior cervical discectomy fusion surgeries.
Some researchers,,,,, reported a 100% fusion, whereas Hattou et al. reported a fusion of 86.2% using PEEK plus bone grafts. Lovasik et al. reported a 99% fusion, whereas Kim et al. reported a fusion of 81.3% using PEEK plus artificial materials.
Donor site morbidity, bacterial contamination and viral transmission are some of the disadvantages of using grafts.,, Previous studies conducted have reported 9.4% to 49% of cases with donor site morbidity., However, immediate stabilization was one of the advantages. The ideal grafts must possess no transmission risks for diseases, reasonable costs and osteogenesis capacity.,,,
The filling materials can also be biomaterials, for example β-tricalcium phosphate, demineralised bone matrix, and bone morphogenetic proteins. Biomaterials are criticized mainly because of their high costs. β-Tricalcium phosphate is less expensive when compared to its counterparts such as bone morphogenetic proteins and demineralised bone matrix.,
Empty cages are supported as bony fusion does not occur only within the cage but also around it. Empty cages have advantages, such as short operative time, no requirement of bone harvesting from donor site and no cost for expensive biomaterials.,
Subsidence is usually reported and can be induced by over-curettage of the endplate, over distraction with too tall cage, cage geometry and cage material. In the study conducted by Hattou et al., four patients had no interbody fusion and had secondary displacement with complications, containing spondylolisthesis and bilateral dislocation. Song et al. reported complications of respiratory difficulty in three cases, dysphagia in four cases and hoarseness in one case. Song et al. reported subsidence in three patients with two-level and two patients with one-level. Yson et al. reported subsidence rate of 29% and showed that four cases of PEEK underwent posterior fusion surgery after non-union. Lovasik et al. reported 13.1% of patients with dysphagia post-operation.
Previous studies have reported a consistent rate of 10% to 12% non-fusion for single-level anterior cervical discectomy bone fusion surgery, 20% to 27% for two-level and 30% to 56% for three-level fusion surgery., Age and level of fusion surgery are proven to be vital for success of surgery. The success of surgery also depends upon smoking as nicotine puts the patient at higher risk of failure due to bone growth prevention. Smokers had failure chances of up to 40% of the cases compared with non-smokers at 8%.,
Even though the results are highly significant and favors bone graft as a filler material, more number of case studies and clinical trials are required to further decide the best filler material for different levels of interbody fusion involved. More studies are thus warranted to analyze the radiological and functional outcomes of PEEK plus bone grafts and PEEK plus artificial materials in anterior cervical discectomy and fusion surgery.
PEEK plus bone grafts is a better filler material as compared to PEEK plus artificial materials in anterior cervical discectomy and fusion surgery for multiple levels involved.
Study design, data collection, and manuscript preparation: SS (Sukrit Sharma), SS (Sunil Sharma), and SAG; manuscript preparation and review: SS (Sunil Sharma), SS (Sukrit Sharma), and HSC. All authors read and approved the final manuscript.
Conflicts of interest
The authors received no specific funding for this work.
This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.
The statistical methods of this study were reviewed by researchers and statisticians from Indian Spinal Injuries Centre. Statistical methods in this study are adequately and appropriately implemented. All methods could be replicated and the results could be verified.
Copyright license agreement
The Copyright License Agreement has been signed by all authors before publication.
Data sharing statement
The datasets generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.
Checked twice by iThenticate.
Externally peer reviewed.
Open access statement
This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
C-Editors: Zhao M, Li JY; S-Editor: Li CH; L-Editors: Qiu Y, Wang L; T-Editor: Jia Y
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[Table 1], [Table 2]