Fracture fixation in extremity trauma with carbon fiber-reinforced polyetheretherketone (CFR-PEEK) plates: evidence today

Carbon fibers are fibers of about 5–10 µm the majority of which is composed of carbon atoms. They have unique advantage properties, such as high stiffness, tensile strength, temperature tolerance, chemical resistance, and are lightweight [1, 2]. The widespread use of carbon fiber composites in many fields including aerospace, military, civil engineering, and sporting industries paved the way to expand its use in medicine [2], with numerous applications particularly in orthopaedics including spine, joint arthroplasty and orthopedic trauma [2, 3]. The use of carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implants is an emerging field in orthopaedic surgery because of the numerous advantages this material offers compared to its conventional counterparts (e.g., stainless steel) and these can be summarized as follows: (1) modulus of elasticity close to bone, therefore avoiding stress-shielding and resultant bone resorption (2) radiolucency and therefore enhanced ability to accurately achieve fracture reduction and monitor healing, (3) decreased artefact in Magnetic Resonance Imaging Scans, (4) no metal allergy, and increased osteoinductive properties and biocompatibility with minimal implant-related inflammatory response, (5) absence of cold welding at the plate-screw interface, (4–11). Main disadvantages of these plates include: (1) They cannot be contoured intraoperatively (form memory property) [4, 5]; (2) the increased cost of production, although the commercial price is similar to the conventional metal implants [6]; and (3) radiolucency at the same time may compromise appropriate plate visualization which is crucial to assess position or hardware failure, however radiopaque tantalum markers have been developed as a remedy [7, 8].

However, despite those potential advantages and preliminary reports already dating back to the 1980s [9], and their use steadily increasing recently, limited amount of studies exist in the literature. There have been sporadic reviews on the subject [2, 3, 10], mostly reporting their general orthopedic applications throughout the body using a variety of implants but robust systematic reviews are missing. The purpose of this study therefore was to conduct a focused systematic review to report the outcomes and complications of CFR-PEEK plates used for the fixation of extremity fractures.

For this systematic review, the Cochrane methodology for systematic reviews was followed [11]. The work was conducted with reference to a predefined protocol, which was registered with the PROSPERO database (https://​www.​crd.​york.​ac.​uk/​prospero/​) (CRD42021245114). The strategy for the systematic literature search included: (i) searching of electronic bibliographic databases, and (ii) scrutiny of references of included studies and any identified systematic review. The following electronic bibliographic databases were searched on March 2021 with no publication year limit: MEDLINE—Interface: EBSCOhost; EMBASE—Interface: Ovidsp; CINAHL (1961 to present)—Interface: EBSCOhost; CENTRAL (1988 to present)—Interface: Cochrane Library. There was a language limit because of limited access to translators and resources. Therefore, only studies available in English language were included. Age was not set as a limit to the search because of the difficulty of setting specific search terms, but all titles and abstracts about children (age < 16 years) were excluded whilst screening. The search in all databases was performed with a combination of keywords in multiple searches. Keywords were combined with the Boolean operators OR and AND. The selected keywords and the strategy for combining these keywords in five searches are summarized in Table 1.

There were two RCTs [18, 19] which were assessed for their methodological quality using the Cochrane Risk of Bias Tool [12]. The results of the assessment are shown in Table 3. One RCT had three key domains with unclear risk of bias (sequence generation, allocation concealment, blinding of the participants) [19]. The other study had adequate sequence generated, concealed allocation and blinding of participants without any other source of bias; hence, it can be classified as low risk of bias [18].

The Newcastle–Ottawa scale (NOS) was used to assess the methodological quality of the three prospective cohort studies included in the review [13]. The results are summarised in Table 4 below. All three studies were rated ‘good quality’ (for threshold see legend in Table 4), with two studies scoring the highest score of nine stars [20, 21]; and one study scoring seven stars [22].

The MINORS criteria were used to assess the methodological quality of the four retrospective cohort studies (Table 5) [14]. The lowest score was 18 out of 24 points for two of the studies [23, 26]. The highest score was 20 out of 24 points [25]. All studies clearly stated their aim, had adequate control and contemporary groups, and performed adequate statistical analysis. Three studies also included consecutive patients [24‐26].

The GRADE approach was used to assess the overall quality of evidence in this review and the following ratings are reported [15]. The review included two RCTs but also seven non-randomised studies, so the starting rating of the study was ‘low quality’ evidence. The study had some inconsistency with methodological and clinical heterogeneity, having three different study designs, different anatomic areas for fixation, and differences in some population characteristics, even amongst the same study designs. However, there was no significant variability in the reported results. Overall, there were no concerns for indirectness, publication bias and imprecision. Based on this assessment, evidence is rated as ‘low quality’.

Although CFR-PEEK implants have been around for years and have several advantages [4, 8, 18‐20, 23, 25, 26], they are slowly regaining popularity and have been used in a variety of orthopedic applications including trauma, infection, and tumors [5]. This is the first systematic review providing evidence regarding the use of CFR-PEEK plates in extremity trauma. Overall results indicate very high union rates similar to conventional plates when used for fixation of either upper or lower limb fractures with similarly good clinical outcomes/scores. The rate of complications is low and comparable to that reported in the literature for their conventional counterparts.

For this review only Level I–III evidence studies, both randomised and non-randomised, were included. However, there were enough retrospective case series studies (Level IV) that were excluded from the analysis. During screening of the available evidence, ten relevant retrospective case series studies were identified [4, 6, 8, 28‐34]. Acknowledging the limitations of such study designs, it is worth to summarise and note their findings on the use of CFR-PEEK plates in fracture fixation. The characteristics and the findings of these case series studies are summarised in Table 10.

Our study compared the outcomes and complications of fracture fixation with CFR-PEEK plates versus conventional plates in the proximal humerus, distal radius, distal femur, and ankle. CFR-PEEK plates have major advantages over conventional plates, include a modulus of elasticity comparable to bone, radiolucency, decreased artefact on CT and MRI, higher biocompatibility with absence of allergies and inflammatory reactions and no cold-welding. Our findings show that CFR-PEEK plates have very high union rates in extremity fracture fixation similar to conventional plates with comparable good clinical outcomes and a very low and comparable rate of complications. Future larger scale prospective studies could provide further robust evidence of their benefits. Considering their advantages, which are reflected in favourable not yet statistically significant trends across different anatomical regions, CFR-PEEK plates seem to be a valid alternative to conventional plating.