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Incomplete Seating of a Metal-backed Alumina
Liner in Ceramic-on-Ceramic Total Hip Arthroplasty
Read Complete Medical Study
http://www.orthosupersite.com/view.asp?rid=59371
By Jaime A. Carvajal Alba, MD; Eric D. Schiffman, MD; Sean P. Scully, MD, PhD;
Hari K. Parvataneni, MD
ORTHOPEDICS 2010; 33:15
Metal-backed modular ceramic bearing systems using a
recessed alumina liner in a titanium sleeve were developed to decrease ceramic
chipping or fracture due to femoral neck impingement after total hip
arthroplasty (THA). However, malseating of the metal-backed ceramic liner has
recently been described. The goal of this study was to assess the prevalence,
etiology, and clinical relevance of this event.
Between 2005 and 2008, 51 consecutive patients (61 hips) underwent THA with a
metal-backed alumina liner housed in a titanium shell. The metal-backed ceramic
liner was aligned, seated, and impacted into the shell, and satisfaction in
terms of liner stability and seating was confirmed intraoperatively.
Postoperative assessment of seating was assessed with standard radiographs.
Liner seating was classified as well seated, suspicious, or malseated.
Seven liners (11.5%) were found to be malseated and 4 (6.5%) were considered
suspicious. Radiographically, there was a gap between the liner and the shell
located inferomedially in 4 patients and superolaterally in 3 patients. Two
liners subsequently seated at 1 and 3 months postoperatively, respectively. No
dislodgement, failures, or adverse events were identified. There were no
revision surgeries. The significant percentage of malseated liners were
potentially attributed to poor exposure, bony/soft tissue interposition, and
surgeon learning curve...
...All liners that were considered unseated were
implanted during the surgeon’s first year of experience using this system, which
may suggest that there is a learning curve with the insertion of this device
that may have an impact on the incidence of this event.
...Patient age plays an important role in THA.
Different studies have reported on the improved performance of alternative
bearing surfaces, especially ceramic materials, when used in younger patients
with higher physical demands. Better longevity of these implants is expected due
to the lower wear rates associated with lower incidence of osteolysis and
aseptic loosening.5-7 Average patient age in our study was 44 years, reflecting
the trend to use alternate bearing surfaces in patients younger than 50 years.
...Squeaking and ceramic fracture are causes of
concern when considering ceramic-on-ceramic couples in THA. Squeaking appears to
be related to implant design, femoral neck impingement, and a sliding motion of
the ceramic head against the liner during specific movements of the operated
hip...
...According to previous reports, the incidence of
ceramic liner malseating ranges from 7.2% to 16.8%.15,16 Miller et al16 reported
an incidence of 7.2% liner malseating in a series of 694 patients who underwent
ceramic-on-ceramic THA. Langdown et al15 reported 19 malseated liners (16.8%)
among 117 THAs using this device...
...Malseated liners may become spontaneously seated
postoperatively. Among the malseated liners identified in our study, 2 liners
showed consequent seating at 1 and 2 months postoperatively, respectively. This
event was also noted by Langdown et al,15 who reported that 2 of 19 malseated
liners in their series became spontaneously seated during the early
postoperative period...
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