Femoral Head Penetration of Vitamin E-Infused Highly Cross-Linked Polyethylene Liners: A Randomized Radiostereometric Study of Seventy Hips Followed for Two Years.
BACKGROUND
Highly cross-linked polyethylene infused with vitamin E (E-poly) was developed to increase oxidative resistance without affecting mechanical properties. We evaluated this type of polyethylene in a randomized clinical study that used radiostereometric analysis. Our objective was to compare the early-term femoral head penetration of an E-poly liner with that of a heat-treated polyethylene liner, ArComXL. We hypothesized that the clinical outcome at two years following total hip arthroplasty would be unaffected by the choice of polyethylene.


METHODS
In this prospective study, sixty-one patients (seventy hips) with noninflammatory hip osteoarthritis and a median age of fifty-eight years were randomized to receive either an implant with an E-Poly or a heat-treated highly cross-linked polyethylene liner. The patients were followed for two years and evaluated at three time points (three months, one year, and two years).


RESULTS
The median proximal penetration in the E-poly group increased from 0.04 mm at three months to 0.06 mm at two years of follow-up. Corresponding values for the ArComXL group were 0.03 mm and 0.10 mm. In both groups, significantly increased penetration was observed between three months and two years (E-poly, p = 0.02; ArComXL, p < 0.001), but between one and two years, the increase was significant only in the control group (E-poly, p = 0.23; ArComXL, p = 0.002).


CONCLUSIONS
The femoral head penetration of E-poly was very low at two years. Whether the increase observed between three months and two years was caused by creep, deformation, wear, or a combination of these cannot be determined by our study. There were no significant differences observed in femoral head penetration rates between E-poly and ArComXL. Currently, the theoretical advantages of E-poly remain to be confirmed.
Department of Orthopaedics, Sahlgrenska University Hospital, Göteborgsvägen 31, SE-431 80 Mölndal, Sweden. E-mail address for B. Shareghi: bita.shareghi@vgregion.se. E-mail address for P.-E. Johanson: per-erik.johanson@vgregion.se. E-mail address for J. Kärrholm: johan.karrholm@vgregion.se.
Bita
B
Shareghi
Department of Orthopaedics, Sahlgrenska University Hospital, Göteborgsvägen 31, SE-431 80 Mölndal, Sweden. E-mail address for B. Shareghi: bita.shareghi@vgregion.se. E-mail address for P.-E. Johanson: per-erik.johanson@vgregion.se. E-mail address for J. Kärrholm: johan.karrholm@vgregion.se.
Per-Erik
PE
Johanson
Department of Orthopaedics, Sahlgrenska University Hospital, Göteborgsvägen 31, SE-431 80 Mölndal, Sweden. E-mail address for B. Shareghi: bita.shareghi@vgregion.se. E-mail address for P.-E. Johanson: per-erik.johanson@vgregion.se. E-mail address for J. Kärrholm: johan.karrholm@vgregion.se.
Johan
J
Kärrholm
D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005270:Femur Head / Q000187:drug effects*; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000601:surgery; D010147:Pain Measurement; D011095:Polyethylenes / Q000737:chemistry; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D059869:Radiostereometric Analysis; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D013997:Time Factors; D014810:Vitamin E / Q000494:pharmacology*
D011095:Polyethylenes; D014810:Vitamin E