DOS BULLETIN - Dansk Ortopædisk Selskab

2010-378_DOS nr. 3 2010 29/09/10 10:08 Side 138
Preheating of cemented femoral component in THA.
Prospective randomized study using RSA, DXA and
clinical scores
Juozas Petruskevicius, Mogens Berg Laursen,
Mogens Brouw Jørgensen, Kjeld Søballe, Poul Torben Nielsen
Department of Orthopedic Surgery, Orthopedic Division, Northern
Denmark Region, Aalborg Hospital, University of Aarhus;
Department of Orthopaedics, University Hospital of Aarhus
Background: Recently published biomechanical studies showed that preheating
of femoral component reduces the cement porosity on prosthesis-cement
interface and enhances the interfacial shear strength. This might increase the
stable fixation of stem in-vivo.
Purpose: The aim of the study was to compare the migration rates, measured
by radiostereometry when cementing matt- surfaced Ti femoral component preheated
to 40° C with the same stem of room temperature. Secondly, we aimed
to compare the periprosthetic bone changes and clinical outcomes of stems during
the 2 years follow-up period.
Methods: We designed a prospective randomized double-blinded study to compare
the migration rates of a preheated (40°C) and non-preheated stem, using
radiostereometry (RSA). The periprosthetic bone density and clinical outcomes
were also registered. Eighty patients undergoing hybrid hip arthroplasty with
cemented matt- surfaced Ti stem (Bi-Metric®, Biomet) were randomized to two
treatment groups with 40 in each. The patients were examined using RSA,
DXA, VAS and Harris Hip Score (HHS) during 2 years follow-up. Migration of
femoral head centre, prosthesis tip and cement mantle’s translations were compared
at 3, 12 and 24 months.
Findings: Migration rates of both femoral head centre and tip was reduced for
preheated stems compared with non- preheated at prosthesis-cement interface.
The median femoral head subsidence for the preheated group was -0.06mm vs.
-0.1mm the control group (p=0.01) at 3 months. This difference remained at the
following examinations and was statistically significant at 24 months too (-
0.17mm vs. -0.24mm; p=0.04). Subsidence occurred mainly at prosthesiscement
interface, while the cement mantle migrated proximally i.e. opposite to
stem. We observed a correlation between male sex, increasing BMI and
increased femoral head migration. DXA scans, HHS and VAS scores revealed
no significant differences between the groups at any follow-up occasion.
Conclusion: We concluded that stem preheating enhances in-vivo stability of
cemented matt-surfaced Ti femoral component.
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