Patients with degenerative hip disease who received a highly cross-linked polyethylene liner during total hip replacement experienced significantly reduced wear and had greater implant survival at 10 postoperative years than patients who received ultra-high molecular weight polyethylene liners, according to study results.
Peter A. Devane
Peter A. Devane, MBChB, MSc, FRACS, and his colleagues randomly assigned 122 patients undergoing total hip arthroplasty for degenerative hip disease to receive either a Enduron conventional ultra-high molecular weight polyethylene liner (UHMWPE) (DePuy) or a Marathon highly cross-linked polyethylene liner (XLPE) (DePuy). Researchers collected Oxford Hip Scores and SF-12 Healthy Survey scores in 91 patients who were available for follow-up at 10-years postoperatively. They also used validated software to analyze radiographs for osteolysis and for 2-dimensional, 3-D and volumetric wear.
Results showed a mean wear rate of 0.03 mm per year and of 0.27 mm per year for patients in the highly XLPE liner group and UHMWPE group, respectively. There was a significantly lower prevalence of osteolysis in the highly XLPE liner group at 10-years postoperatively. Despite that finding, Devane said in an interview with Orthopedics Today it was surprising osteolysis could still occur when highly cross-linked polyethylene was used.
“We believe the osteolysis seen with the highly [cross-linked polyethylene liner] XLPE in our study came from premature loosening of a less than optimal cemented femoral stem,” Devane told Orthopedics Today.
Similarly, patients in the highly XLPE group had a significantly lower revision rate, according to results, with 10 of 12 revisions being in the UHMWPE liner group. However, researchers found no significant differences between the groups based on the Oxford Hip Scores or SF-12 mental or physical well-being scores.
The study is limited as it is a single center study with polyethylene liners analyzed from a single manufacturer that were analyzed, and it has the potential for underreporting of osteolysis with anteroposterior and lateral radiographs used instead of CT or MRI, Devane noted.
But he said surgeons can be confident in their use of highly XLPE in THR.
“Surgeons are able to offer total hip replacement with this bearing surface to patients with confidence that their prosthesis will last substantially longer than previous conventional polyethylene, which has been quoted at 15 years,” Devane said. “This allows total hip to be performed in much younger patients than previously thought, with the knowledge it may be their only operation,” he said. – by Casey Tingle
Devane PA, et al. J Bone Joint Surg Am. 2017;doi:10.2106/JBJS.16.00878.
Peter A. Devane, MBChB, MSc, FRACS, can be reached at Wellington Hospital, Riddiford St., Newtown, Wellington 6021, New Zealand; email: firstname.lastname@example.org.
Disclosure: Devane reports he received grants from DePuy and has a patent US 8,659,591 B2 issued to Peter Devane.