Advertisement for orthosearch.org.uk
Orthopaedic Proceedings Logo

Receive monthly Table of Contents alerts from Orthopaedic Proceedings

Comprehensive article alerts can be set up and managed through your account settings

View my account settings

Visit Orthopaedic Proceedings at:

Loading...

Loading...

Full Access

General Orthopaedics

Debonding of the Porous Coating of the Acetabular Component: A Late Failure Mode of Hip Resurfacing Arthroplasty

International Society for Technology in Arthroplasty (ISTA)



Abstract

Introduction:

Uncemented acetabular component fixation has been considered the most reliable fixation method in contemporary metal-on-metal hip resurfacing arthroplasty (HRA). During prospective long-term follow-up of a HRA device, we have encountered a surprisingly high incidence of this complication and wish to alert surgeons and manufacturers of this problem.

Methods:

The study group was comprised of all 373 HRAs performed by a single surgeon using this hybrid hip resurfacing implant from May 2001 to March 2005. The acetabular component features a dual-coated bone ingrowth surface of plasma-sprayed titanium plus hydroxylappatite. There were a total of 34 revisions identified at the time of this study.

Results:

There were 5 other cases (1.3%) of late acetabular loosening all occurring greater than 8 years postoperatively at an average of 9 ± 1 years after the primary surgery. All of theses patients were functioning well with radiographically stable implants for at least 8 years. Intraoperative findings included debonding of large portions of the porous coating which remained adhered to the underlying bone. We concluded that these cases represented primary mechanical implant failures. There was a moderate amount of wear debris, presumably from the backside. There was no bone loss evident. There were no soft tissue masses. There were also 2 cases of adverse wear failure with pain and soft tissue masses diagnosed preoperatively with well-fixed implants. One of these patients also suffered component debonding prior to revision. Two (2/5; 40%) cases had an acetabular inclination angle ≥50°. Implant Debonding accounted for 5/8 (63%) of all acetabular failures and 14.7% (5/34) of all failures, while failure of ingrowth caused only 1/34 (3%) and adverse wear failures accounted for only 6% (2/34) of all failures.

Conclusion:

We recommend that manufacturers re-evaluate the fixation strength of their own particular methods of bonding titanium plasma spray to a cobalt-chrome substrate, particularly in regards to fatigue failure and that they make improvements to ensure a longer duration of bone-implant fixation.


*Email: