Custom-made 3D-printed cup-cage implants for complex acetabular revisions

evaluation of pre-planned versus achieved positioning and 1-year migration data in 10 patients

Abstract

Background and purpose — The use of custom-made
3D-printed titanium implants for the reconstruction of large
acetabular defects has been successively introduced in the
last decade. In an observational cohort study we evaluated
the agreement between preoperatively planned and actually
achieved cup-cage position as well as 1-year follow-up
migration of the cup-cage component.

Patients and methods — 10 patients with Paprosky
III defects underwent revision surgery using a custom-made
3D-printed cup-cage. The position of the implant on postoperative
CT scan was compared with the preoperative plan
and the postoperative CT scan was compared with the 1-year
follow-up CT scan.

Results — There was a median deviation in postoperative
position versus planned in inclination of 3.6° (IQR 1.0–5.4),
in anteversion of –2.8° (IQR –7.5 to 1.2), and in rotation of
–1.2° (IQR –3.3 to 0.0). The median deviation in position
of the center of rotation (COR) was –0.5 mm (IQR 2.9 to
0.7) in the anteroposterior (AP) plane, –0.6 mm (IQR –1.8
to –0.1) in the mediolateral (ML) plane, and 1.1 mm (IQR
–1.6 to 2.8) in the superoinferior (SI) plane. The migration
between postoperative and 1-year follow-up caused a mean
change in inclination of 0.04° (IQR –0.06 to 0.09), in anteversion
of –0.13° (IQR –0.23 to –0.06), and in rotation of
0.05° (IQR –0.46 to 1.4). The migration of COR was –0.08
mm (IQR –0.18 to –0.04) in the AP plane, 0.14 mm (IQR
–0.08 to 0.22) in the ML plane, and 0.06 mm (IQR –0.02 to
0.35) in the SI plane. There was no re-revision.

Interpretation — The early results show good agreement
between planned and achieved cup-cage position and small
measured migration values of the cup-cage component at the
1-year follow-up.