Introduction. Modular tantalum augments have been introduced to manage severe bone defects in hip and knee revision surgery. The porous surfaces of tantalum augments are intended to enhance osseointegration and a number of studies have documented their excellent biocompatibility. However, the characteristics of tantalum augment osseointegration on human ex vivo specimens from re-revision procedures have not been reported so far. Methods. Out of a total number of 324 hip and knee revisions with a tantalum augment performed in our institution between 2007 and 2010 four patients had to be re-revised at a mean followup time of 15 months. The causes for re-revision were a periprosthetic acetabular fracture in one, a loosening of a tibial component in one and periprosthetic hip infections in two cases. To characterize osseointegration of the tantalum augments, they were removed during revision surgery and subjected to undecalcified processing. All specimens were analysed by contact radiography, histology (toluidine blue, von Kossa) and quantitative histomorphometry. Results. In all specimens trabecular ingrowth was apparent along the former bone-augment-interface. The depth of bone ingrowth into the porous microarchitecture of the augments reached up to 2000 μm. Thin-section analysis revealed scattered and partially mineralized bone forming units within the interior of the augments. Conclusions. To the best of our knowledge this is the first histomorphometric analysis on the osseointegration of tantalum augments in human ex vivo specimens. In the presented series
Early total hip replacement (THR) for acetabular
fractures offers accelerated rehabilitation, but a high risk of heterotopic
ossification (HO) has been reported. The purpose of this study was
to evaluate the incidence of HO, its associated risk factors and
functional impact. A total of 40 patients with acetabular fractures
treated with a THR weres retrospectively reviewed. The incidence
and severity of HO were evaluated using the modified Brooker classification,
and the functional outcome assessed. The overall incidence of HO
was 38%
(n = 15), with nine severe grade III cases. Patients who underwent
surgery early after injury had a fourfold increased chance of developing
HO. The mean blood loss and operating time were more than twice
that of those whose surgery was delayed (p = 0.002 and p <
0.001,
respectively). In those undergoing early THR, the incidence of grade
III HO was eight times higher than in those in whom THR was delayed
(p = 0.01). Only three of the seven patients with severe HO showed
good or excellent Harris hip scores compared with eight of nine
with class 0, I or II HO (p = 0.049). Associated musculoskeletal
injuries, high-energy trauma and head injuries were associated with
the development of grade III HO. The incidence of HO was significantly higher in patients with
a displaced acetabular fracture undergoing THR early compared with
those undergoing THR later and this had an adverse effect on the
functional outcome. Cite this article:
