Medical Device Daily Associate

Biomet (Warsaw, Indiana) said the FDA has granted marketing clearance for its second-generation, highly crosslinked polyethylene, ArComXL, an engineered polymer that the company said has demonstrated a 47% to 64% volumetric wear rate reduction over the first-generation ArCom Polyethylene.

"ArComXL is a new bearing material based on the already proven ArCom product that delivers superior wear characteristics without the adverse consequences of reduced mechanical integrity or potential for oxidation that defines the currently marketed generation of highly crosslinked polyethylenes," President and CEO Dane Miller, PhD, said in a statement. "ArComXL sets a new performance standard in terms of mechanical strength, oxidation resistance, and wear resistance in polyethylene, which is attributable to our patented processing technique."

Biomet said it is the only orthopedic company to offer a second-generation highly crosslinked polyethylene material.

Derek Edgar, a Biomet product manager who works on the ArCom line, said the first-generation product was developed in the early 1990s. "We were and still are the only company to manufacture our polyethylene in-house through what we call isostatic compression molding," he told Medical Device Daily.

Extensive in vitro testing was conducted internally and in conjunction with independent laboratories to measure metrics such as resistance to abrasive wear, subluxation wear, oxidation, fatigue and crack propagation. The results of comparison testing to ArCom were universally positive and have validated the utility of Biomet's patented process, the company said.

Aside from the enhanced volumetric wear-rated reduction, the company also reported a 30% increase in ultimate tensile strength in longitudinal axis and no measurable oxidation by Fourier Transform Infrared Spectroscopy after accelerated aging (OI less than 0.4) with the ArComXL product

Biomet said that ArComXL will not replace its traditional ArCom material, but will be another bearing option from which surgeons can choose.

According to Edgar, the market will ultimately dictate whether the ArComXL will supplant the use of the original material in the company's hip implants. "I would expect that . . . we're going to see a high proportion of our polyethylene liners be the AroComXL material," he said.

Edgar noted that while the ArCom product also is used in artificial knee bearings, Biomet currently has no plans to utilize the new material for other applications outside of hips. He said that ArCom is a direct-compression molded material that can be made for individual applications, but with ArComXL, "due to the highly crosslinking doping process it's not conducive to knee bearings, because we have to machine them and we don't want to machine tibial bearings."

To simultaneously increase the wear resistance and mechanical strength, Edgar said the company had to elevate the level of gamma radiation from 33 kilograys with ArCom to 50 kilograys with ArComXL. He said that while there was a degradation of mechanical strength that goes along with that increase in radiation, "we counter that with a process that we call solid-state depravation."

He said this process "quenches" some of the free radicals that are generated from the gamma radiation step and also does something that he called longitudinal polymer orientation, a patented process by which the carbon chains of the material are mechanically stretched out along the longitudinal access of the bar.

"Essentially what we've done is added strength to the material by mechanically deforming it," he said.

"ArComXL offers substantial advantages over the first-generation highly crosslinked materials still promoted by our competitors," Miller added in the company statement. "And as the first and only company to market directionally engineered polyethylene, we expect to enjoy a strong technological advantage in the highly crosslinked market for a significant period of time."

Biomet's product portfolio encompasses reconstructive products, including orthopedic joint replacement devices, bone cements and accessories; dental reconstructive implants; fixation products, including electrical bone growth stimulators, internal and external orthopedic fixation devices, craniomaxillofacial implants and bone substitute materials; spinal products, including spinal stimulation devices, spinal hardware and orthobiologics; and other products, such as arthroscopy products and softgoods and bracing products.