How accurate can a custom-made implant be positioned in large

acetabular defects?

Marieke BaauwGijs van Hellemondt

Bart SwierstraMiranda van Hooff

Maarten Spruit

Disclosure

• Two authors (GH and MS) are paid faculty for Mobelife, Leuven, Belgium.

Defect analysis and classification

Defect analysis and classification

Defect analysis and classification

Pre-op planning & implant design– Custom porous augment and custom plate: monoblock or

modular– Inclination, anteversion angle and center of rotation

Surgery

AP radiographs pre- and post-op

Methods

• 16 cases with Paprosky type 3 defects• Pre- and post operative CT-scans• Comparison of INCL, AV, ROT and COR

Results

• 9 implants perfectly positioned• 7 implants were malpositioned in one or more

parameters – 1 with respect to INCL (> 10°)– 3 with respect to AV (> 10°)– 4 with respect to rotation (> 10°)– 5 with respect to the COR (> 5mm )

• One intra-operative complication: anterior wall acetabular fracture.

Discussion

• No literature to directly compare with• Free hand cup positioning is inaccurate even

in pimary hip surgery• With Patient specific implants in primary hips

slightly better• Compared to existing literature on acetabular

component placement in less challenging defects our results are at least comparable.

Discussion

• Clinical results:–26 patients– FU 3-36 months–1 dislocation–No infection–No implant removal