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Better fit, rotational alignment seen with customized TKA implants vs off-the-shelf implants
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Compared with off-the-shelf implants, customized implants for total knee arthroplasty provided better rotational alignment and tibial fit without tibial tray overhang, according to recently published results.
Gregory M. Martin, MD, from Preferred Orthopedics of the Palm Beaches, and colleagues compared the component fit in four tibial zones of a customized implant with three different off-the-shelf TKA designs in 44 knees. Investigators used a CT-based computer-aided design model analysis to evaluate the rotational alignment of the tibia.
Results showed there were more customized implants with optimal fit compared with the off-the-shelf implants. The customized implants also had significantly better component fit compared with the off-the-shelf TKAs. As the customized implant was designed along the tibial rotational axis, no deviation was seen.
When the medial one-third of the tibial tubercle was used as a rotational landmark, 95% of the off-the-shelf trays and 73% of the customized implant tibial trays demonstrated a rotational deviation of more than 5°. There was a rotational deviation of more than 10° in 73% of the off-the-shelf trays and in 27% of the customized implant tibial trays.
“This data is interesting since approximately 20% of patients are not satisfied after off-the-shelf total knee arthroplasty and at least 15% of patients have residual pain,” Martin told Healio.com/Orthopedics. “We know from prior studies that tibial component overhang and tibial malrotation significantly increase the chance of a poor result. Our study demonstrated that 18 % of the time the-off-the shelf implants had clinically significant overhang vs. 0% of customized implants, and 45% of the time off-the-shelf knees had rotational errors when sized appropriately vs. 0% of customized knees.”
He added, “Customized knees need to be taken seriously as a way of improving clinical outcomes after total knee arthroplasty by eliminating the compromise between tibial fit and rotation.” – by Monica Jaramillo
Disclosure: Martin reports he received intellectual property royalties from and is a paid consultant for, is paid presenter or speaker for, receives research support from and has stock or stock options in ConforMIS; has stock or stock options in System4Health; and receives publishing royalties and financial or material support from UpToDate.
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