Five-year Experience with Crossfire?? Highly Cross-linked Polyethylene

Highly cross-linked polyethylene has been associated with low in vitro wear, but also has decreased in vitro ultimate yield strength. We therefore asked whether highly cross-linked polyethylene would result in lower outcome scores, wear, or early failure in a young patient population. Seventy THAs in 64 patients were performed using a highly cross-linked (electron beam-irradiated to 9 Mrads) acetabular liner and a cobalt-chrome femoral head. The average age of the patients at surgery was 41 years (range, 19-50 years). The minimum followup was 2.4 years (average, 4 years; range, 2.4-6.5 years). We recorded demographic and clinical data, including Harris hip score. Polyethylene wear measurements were analyzed with a validated, computer-assisted, edge detection method. The average Harris hip score improved from 53 to 92 at last followup. There was no evidence of acetabular or femoral loss of fixation, subsidence, or loosening. Linear wear was undetectable at this followup interval. No patient experienced catastrophic failure or underwent revision surgery. These data show low polyethylene wear rates and no catastrophic failures at early followup in a young patient cohort.

Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 47%

THA with Highly Cross-linked Polyethylene in Patients 50 Years or Younger

Shia¹,

Clohisy²,

Schinsky³

et al. 2009

“…For annealed and gamma inert sterilized highly crosslinked components, in vivo oxidation occurs preferentially at the rim of the liner, which has the greatest exposure to oxygen-containing body fluids and tissues [17]. Previous studies have reported lower oxidation of the bearing surface for annealed and gamma inert sterilized highly crosslinked liners [7,18] as compared with the rim and may explain the general preservation of wear properties seen in clinical studies [9,18,28]. However, in the case of a malfunctioning hip such as chronic instability with dislocation, rim oxidation may contribute to localized delamination or rim fracture [18].…”

Section: Introductionmentioning

confidence: 99%

Do First-generation Highly Crosslinked Polyethylenes Oxidize In Vivo?

MacDonald

Sakona

Ianuzzi

et al. 2011

Background Highly crosslinked and thermally treated polyethylenes were clinically introduced to reduce wear and osteolysis. Although the crosslinking process improves the wear performance, it also introduces free radicals into the polymer that can subsequently oxidize. Thermal treatments have been implemented to reduce oxidation; however, the efficacy of these methods with regard to reducing in vivo oxidative degradation remains to be seen. Polyethylene oxidation is a concern because it can compromise the ultimate strength and ductility of the material. Questions/purposes We analyzed the oxidation, oxidation potential, and mechanical behavior of thermally treated highly crosslinked polyethylene retrieved acetabular liners. Methods Three hundred seven acetabular liners were collected from consecutive revision surgeries at six institutions over a 10-year period. Twenty-four were sterilized using nonionizing methods, 43 were sterilized in an inert environment, 80 were highly crosslinked and annealed, and 160 were highly crosslinked and remelted. Oxidation and oxidation potential were assessed by Fourier transmission infrared spectroscopy. Mechanical behavior was assessed by the small punch test. Results Oxidation and hydroperoxide (oxidation potential) indices were elevated in the annealed and gamma inert sterilized groups compared with those of the remelted liners and uncrosslinked gas sterilized controls, particularly at the rim. We also detected an increase in oxidation over time at the bearing surface of the remelted group. Ultimate strength of the polyethylene at the bearing surface was negatively correlated with implantation time for the annealed liners. Conclusions Within the first decade of implantation, the clinical outlook for first-generation highly crosslinked polyethylene remains promising. However, ongoing research continues to be warranted for first-generation highly crosslinked polyethylene bearings to monitor the implications of elevated oxidation at the rim of annealed liners as well as to better understand the subtle changes in oxidation at the bearing surface of remelted liners that occur in vivo.

“…However, studies reporting on the midterm (C 5 years average followup) in vivo performance of these PE liners are scant [1,4,7,9,37]. Such studies are of utmost importance because radiographic osteolysis is a phenomenon rarely seen before 5 years of followup.…”

Section: Introductionmentioning

confidence: 99%

Wear is Reduced in THA Performed with Highly Cross-linked Polyethylene

Beksaç

Salas²,

Valle

et al. 2009

Highly cross-linked polyethylene (HCLPE) has been used extensively to decrease osteolysis and related implant failure in THA. We compared the wear rate of HCLPE and noncross-linked conventional PE (CPE) liners and the rate of radiographic calcar resorption and osteolysis in young patients (35-60 years of age) who underwent THA by one surgeon. Thirty-four patients (41 THAs) who received a hybrid THA using a HCLPE liner were matchpaired for age, gender, body mass index, and diagnosis with a group of patients who underwent THA with identical implants but with a CPE liner. The minimum followup was 4 years (average, 5.3; range, 4-8 years). Using the Livermore measurement technique, the averages of total wear of the HCLPE and CPE liners were 0.01 mm (range, -0.23-0.4) and 0.64 mm (range, 0-1.7), respectively. The average annual wear was less for the HCLPE than the noncross-linked PE (0.002 mm, range, -0.05-0.1 versus 0.12 mm, range, 0-0.29, respectively). Four hips in the HCLPE group and 23 in the CPE group had calcar resorption measuring averages of 2.5 mm (range, 2-3) and 7.5 mm (range, 1.8-23.8), respectively. Periprosthetic osteolysis occurred in two and eight hips in the HCLPE and CPE groups, respectively. Longer followup is needed to determine if these findings will result in improved implant survivorship.