Table 4.
In vivo animal model studies testing biocompatibility
| Study | Animal | Model | Test material | UHMWPE comparator? |
Outcomes | Relative reactivity |
|---|---|---|---|---|---|---|
| Latif et al. [26] | Rat | Air pouch | CFR-PEEK | Yes* | Test intervals: 1, 3, and 10 days; outcomes: visual scoring system; pouch thickness; localization of macrophages (ED1 antigen staining); vascular proliferation (ICAM1 staining); results: visual scoring system showed PE to cause more inflamed than CFR-PEEK; no differences in pouch thickness for all variables; no difference between polyethylene and CRF-PEEK for ED1 staining or ICAM1 staining | – |
| Kabir et al. [23] | Rabbit | Epidural | PEK | Yes | Test intervals: 3 and 6 months; outcomes: neurobehavioral observations (weekly); inflammation identified via histology; results: no neurological deficits or systemic toxicity; crystalline wear debris identified and surrounded by inflammatory cells; inflammation and angiogenesis limited to periparticle epidural space | – |
| Utzschneider et al. [44]† | Mouse | Knee | CRF-PEEK (pitch) CRF-PEEK (Pan) |
Yes | Test intervals: 1 week; outcomes: synovial microcirculation assessment; fraction of rolling leukocytes; histology (H&E); synovial membrane thickness; results: no difference in functional capillary density, fraction of rolling leukocytes, nor the number of leukocytes adhered to the endothelium between particle groups; no differences in histological scoring for inflammation or synovial membrane thickness were identified between particle groups; the control group had a significant reduction in each of the aforementioned variables compared with the particle groups | – |
| Cunningham et al. [6] | Rabbit | Epidural | PEEK | Yes | Test intervals: 3 and 6 months; outcomes: histology (H&E and HAM-56 staining); cytokine analysis (ABC method; TNF-α, TNF-β, IL-1α, IL-1β, and IL-6); results: PEEK exhibited a reduced cytokine expression relative to UHMWPE | (−) |
| Lorber et al. [29]† | Mouse | Knee | CRF-PEEK (pitch) CRF-PEEK (Pan) |
Yes | Test intervals: 1 week; outcomes: cytokine analysis (ABC method; TNF-α, IL-1β, and IL-6); results: CFR-PEEK (pitch) particles showed significantly increased expression of: TNF-α, IL-1β, and IL-6 in articular cartilage and bone marrow, and TNF-α in the synovial layer when compared with the UHMWPE group; CFR-PEEK (Pan) particles caused increased TNF-α and IL-1β levels in bone marrow compared with UHMWPE particles | (+) |
| Grupp et al. [12] | Rabbit | Epidural | CRF-PEEK | Yes | Test intervals: 3 and 6 months; outcomes: histology (stain not specified); results: wear debris particles surrounded by inflammatory cells were identified in the vertebral canal; inflammation was limited to the epidural space; CFR-PEEK showed a similar histopathological reaction to UHMWPE particles | – |
* Type of polyethylene not specified; †related studies; (+) = increased reactivity; (−) = decreased reactivity; – = similar reactivity; reactivity was judged relative to the within study UHMWPE control; CFR-PEEK = carbon fiber-reinforced polyetheretherketone; ICAM1 = intercellular adhesion molecule 1; H&E = hematoxylin and eosin; TNF = tumor necrosis factor; IL = interleukin.