Poor tibial component fit can lead to issues including pain, loosening and subsidence. Morphometric data, from 30 patients undergoing UKA were utilized; comparing size, match and fit between patient-specific and off-the-shelf implants. CT images were prospectively obtained and implants modeled in CAD, utilizing sizing templates with off-the-shelf and CAD designs with patient-specific implants. Virtual surgery was performed, maximizing tibial plateau coverage while minimizing implant overhang. Each implant evaluated to examine tibial fit. Patient-specific implants provided significantly greater cortical rim surface area coverage versus off-the-shelf implants: 77% v. 43% medially and 60% v. 37% laterally. Significantly less cortical rim overhang and undercoverage were observed with patient-specific implants. Patient-specific implants provide superior cortical bone coverage and fit while minimizing overhang and undercoverage seen in off-the-shelf implants.
Keywords: CT-based imaging; ConforMIS; overhang; patient specific implants; tibial component; unicompartmental knee arthroplasty.
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