Speaker: Consider costs, functional outcomes when selecting articulating spacers for PJI
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Orthopedic surgeons should be familiar with functional outcomes, reported complications and effectiveness of different antibiotics used with articulating spacers implanted to help eradicate joint infection in patients, a presenter said.
At the Musculoskeletal Infection Society Annual Meeting, Curtis W. Hartman, MD, FAAOS, said that compared with static spacers, articulating spacers benefit patients through the ability to flex the knee and to maintain symmetric limb lengths when used in the hip.
Hartman, an associate professor in the department of orthopedic surgery at the University of Nebraska Medical Center in Omaha, Nebraska, discussed the designs and properties of hip and knee articulating spacers, which include self-constructed, prefabricated off-the-shelf, molded and definitive metal and polyethylene designs.
“Importantly, we ought to think about functional outcomes of these spacers,” Hartman said.
“I think, routinely in all of the literature that I’ve surveyed, patients do achieve better range of motion [and] total arc of motion. They do achieve better deep flexion,” compared with
static spacers.
Hartman discussed some pros and cons of self-constructed articulating spacers.
“The most basic form is the so-called self-constructed spacer, where basically you just take antibiotic-loaded cement and mold that into a shape that looks something like a joint and you place that and hope you get some sort of articulation,” he said. In addition, antibiotic-loaded cement may be placed over a metal core to provide added strength and to facilitate earlier weight-bearing, according to Hartman.
In today’s environment of health care cost-containment, the downside is that these spacers are assembled in the OR, which takes extra time to do, he said. “They are fairly time intensive and, as you know, time in the OR is expensive. So, when you compare total costs of the procedure, it may have an impact because of the lost time while creating these spacers.”
He continued, “Another benefit of this is that you can use whichever antibiotic you want in your cement. You can use whatever dose you think is appropriate.”
Molds are available to create an articulating spacer in a “standardized shape” vs. using a free-form hand-molded spacer, according to Hartman.
Antibiotic elution is relatively unknown with prefabricated articulating spacers, Hartman said, noting these spacers are typically made with either gentamycin or gram-positive vancomycin.
Another option he discussed is a definitive metal and a polyethylene implant. “It does appear that these articulating spacers result in better range of motion, better functional outcomes compared [with] static spacers, and they also result in shorter hospital stays,” Hartman said.
As is the case with a native or prosthetic joint, dislocation of the hip or knee is a complication that can occur with an articulating spacer. In the hip, complications also may include femoral fracture, whereas complications with knee articulating spacers include fracture and instability, he said.
Based on his survey of the literature, Hartman said articulating spacers were often associated with better Knee Society Scores.
“I think one of the more important findings in several of the studies were shorter hospital stays. As length of stay in the hospital becomes an important metric that we look at for cost, I think anything that we can do, especially if infection eradication is equal, anything that we can do to shorten those hospital stays is warranted,” he said.
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Hartman CW. Updates in the use of articulating spacers. Presented at: Musculoskeletal Infection Society Annual Meeting; Aug. 6-7, 2021; Fort Lauderdale, Florida (hybrid meeting) .
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