All-polyethylene tibial implants are associated with reduced osteolysis, good survivorship
ORLANDO — A presenter at the Current Concepts in Joint Replacement Winter Meeting made a case for using cemented all-polyethylene tibial components in total knee arthroplasty, saying the components are appropriate for most patients regardless of age or BMI.
“I suspect I’m in the minority in this room in the sense that I use monoblock all-poly tibias in the majority of my knee arthroplasty patients. I’ll try to give you some data to support that position,” Robert T. Trousdale, MD, of the Mayo Clinic, said.
He reviewed some of the advantages of using that particular implant design.
For example, with a monoblock all-polyethylene tibial component, the surgeon can resect less tibial bone and yet implant a component of the same thickness as a modular tibial component, Trousdale said.
“Results of not all, but many modular fixed-bearing designs have been relatively disastrous and one that we spend a lot of time talking about is osteolysis,” he said, showing what he called the “summary slide” listing all the pros of monoblock implants.
“There are data in which there is less osteolysis with some designs,” Trousdale said. “There are data to suggest there is better long-term survivorship than some modular designs. You load the proximal tibia, I think, a little bit better in the long term, and they are cheaper than modular designs.”
A published study conducted at Mayo Clinic that Trousdale discussed, in which results of monoblock all-polyethylene and metal-backed tibial components were compared, showed monoblock designs performed better in some key categories.
“So, across every age group, except the very elderly — so that goes against conventional thought a little bit — the all-polys had a better survivorship compared to metal-backed tibias,” Trousdale said.
Regardless of BMI, “across all groups, except the large patients, all-polys had better survivorship compared with metal-backs,” he said, noting the results also showed a lower infection rate among patients with all-polyethylene tibial implants.
The one negative of cemented all-polyethylene tibial components Trousdale mentioned is the inability to do a late polyethylene exchange.
“Modularity is occasionally needed. You need it in all your revisions, of course, and you need it in your complex primary cases with deformities,” he said. – by Susan M. Rapp
Trousdale RT. Paper 86. Presented at: Current Concepts in Joint Replacement Winter Meeting; Dec. 11-14, 2019; Orlando.
Disclosure: Trousdale reports he receives royalties from DePuy Synthes.