In Vitro Testing of Femoral Impaction Grafting With Porous Titanium Particles: A Pilot Study

Abstract

The disadvantages of allografts to restore femoral bone defects during revision hip surgery have led to the search for alternative materials. We investigated the feasibility of using porous titanium particles and posed the following questions: (1) Is it possible to create a highquality femoral graft of porous titanium particles in terms of graft thickness, cement thickness, and cement penetration? (2) Does this titanium particle graft layer provide initial stability when a femoral cemented stem is implanted in it? (3) What sizes of particles are released from the porous titanium particles during impaction and subsequent cyclic loading of the reconstruction? We simulated cemented revision reconstructions with titanium particles in seven composite femurs loaded for 300,000 cycles and measured stem subsidence. Particle release from the titanium particle grafts was analyzed during impaction and loading. Impacted titanium particles formed a highly interlocked graft layer. We observed limited cement penetration into the titanium particle graft. A total mean subsidence of 1.04 mm was observed after 300,000 cycles. Most particles released during impaction were in the phagocytable range (\ 10 lm). There was no detectable particle release during loading. Based on the data, we believe titanium particles are a promising alternative for allografts. However, animal testing is warranted to investigate the biologic effect of small-particle release.

Better primary stability with porous titanium particles than with bone particles in cemented impaction grafting: Anin vitrostudy in synthetic acetabula

“…Correspondingly, smaller particle diameter (TiP) resulted in less cement penetration than large particles (BoP). When compared to a previous study of impaction grafting with TiP in synthetic femora (mean penetration 0.49 mm) the cement penetration in the acetabular graft layers was rather deep . The timing of cement introduction and pressurizing in the femoral study and this acetabular study were similar.…”

“…Fourth, 1800 loading cycles represent a restricted loading protocol compared to in vivo loading. However, the largest amount of displacement seems to occur within the first thousand loading cycles . Finally, this study focused solely on biomechanical issues, without considerations of involved biological issues.…”

“…Titanium particles (TiP) deform during impaction like bone grafts and create a heavily entangled and macro‐porous graft layer with good resistance to compressive loading . TiP showed good handling characteristics and only limited cement penetration and particle generation in femoral impaction grafting . To achieve osteo‐conductive capabilities comparable to BoP and CeP, TiP should be covered with a bioceramic coating and particles should have a diameter of at least 2.8–4.0 mm .…”

Impactability and time‐dependent mechanical properties of porous titanium particles for application in impaction grafting

“…Reconstructions were made with commercially available femoral revision impaction tools and an Exeter™ hip prosthesis (Size 1; Stryker Orthopaedics) cemented in Sawbones femurs. The impaction debris amounted to 55 ± 18 mg (0.13 wt %) and prolonged loading did not seem to produce additional titanium microparticles 63. In a spinal fusion pseudarthrosis study in rabbits as much as 190 mg phagocytable titanium debris had to applied in order to reduce the fusion rate by 20 % 60.…”

Morsellised sawbones is an acceptable experimental substitute for the in vitro elastic and viscoelastic mechanical characterisation of morsellised cancellous bone undergoing impaction grafting

“…Unfortunately, direct comparison of findings across different experimental studies is problematic due to the lack of standardisation in (i) the test configuration (e.g. Butler et al [40] , Lunde et al ( [41]), Putzer et al [33], Aquarius et al [42], Bolland et al [43]; (ii) the magnitude and frequency of loading (Bavadekar et al [19], Fosse et al [23], Grimm [18], Voor et al [22]; (iv) the origin and treatment of the bone chips (Cornu et al [20], Datta et al [13], Lunde et al ( [44]). One approach that potentially alleviates the difficulties of comparison across studies is to use experimental protocols which enable the bone graft material to be characterised using consolidation models from soil mechanics, such as the Drucker-Prager and Mohr-Coulomb yield criteria.…”