Tricalcium-Phosphate/Hydroxyapatite Bone Graft Extender for Use in Impaction Grafting Revision Surgery – an In Vitro Study in Human Femora

Haaren, E. H. van; Smit, T.H.; Phipps, K.; Wuisman, P.; Blunn, GW; Insley, Gerard; Heyligers, Ide C.

doi:10.4028/www.scientific.net/kem.254-256.667

Cited by 22 publications

(38 citation statements)

References 19 publications

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“…Tricalcium phosphate and HA composite granules or HA granules are mixed with bone particles. Mechanical tests suggest tricalcium phosphate/HA granules (size, 2-4 mm) with a 50% mixture to allograft provided higher initial mechanical stability in axial compression testing [2,22] and impaction grafting using HA granules (size, 0.3-4 mm) with a 50% mixture provided greater rotational stability [8]. Our data suggest the effectiveness for the initial stability of the stem fixed by impaction grafting with HA granules was more obvious with the torsional test.…”

Section: Discussionmentioning

confidence: 77%

Factors Influencing the Stability of Stems Fixed with Impaction Graft in Vitro

Ohashi

Matsuura

Ebara

et al. 2009

Clinical Orthopaedics &Amp; Related Research

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Mechanical stability of the stem is believed to be an important factor in successful impaction grafting in revision THA. We asked whether particle size, femoral bone deficiencies, stem design, graft composition, and impaction technique influenced the initial stability of the stem in vitro using model femora and human bone particles. Bone particles made with a reciprocating blade-type bone mill contained larger particles with a broader size distribution than those made by a rotating drum-type bone mill and had higher stiffness on compression testing. The stiffness on torsional testing decreased as the degree of proximal-medial segmental deficiencies increased. The stiffness and maximum torque in a stem with a rectangular cross section and wide anteroposterior surface were higher in torsional tests. Adding hydroxyapatite granules to the bone particles increased the torsional stability. To facilitate compact bone particles, we developed a spacer between the guidewire and modified femoral packers. This spacer facilitated compacting bone particles from the middle up to the proximal and the technique increased the amount of impacted bone particles at the middle of the stem and also improved the initial stability of the stem. Stem design and degree of deficiencies influenced stiffness in the torsional test and the addition of hydroxyapatite granules enhanced torsional stiffness.

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Section: Discussionmentioning

confidence: 77%

Factors Influencing the Stability of Stems Fixed with Impaction Graft in Vitro

Ohashi

Matsuura

Ebara

et al. 2009

Clinical Orthopaedics &Amp; Related Research

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“…Another study used a cemented model to look at a mixed tricalcium phosphate/HA substitute (BoneSave, Stryker Howmedica Osteonics). 31 It also found less subsidence with 50% graft substitute than with pure allograft (0.99 mm and 2.31 mm, respectively). This experiment did not look at higher mix ratios, and subsidence at the individual prosthesis-cement and cementfemur interfaces was not determined.…”

Section: Discussionmentioning

confidence: 91%

“…11 A study using a more realistic cemented femoral model also suggested that a tricalcium phosphate/ hydroxyapatite (HA) graft substitute decreased subsidence. 31 It is not known whether other graft substitutes have similar effects, or if the effects depend on the proportion of allograft to substitute. The mechanism by which graft substitutes reduce subsidence is also unknown.…”

mentioning

confidence: 99%

A Hydroxyapatite Graft Substitute Reduces Subsidence in a Femoral Impaction Grafting Model

Munro

Downing²,

Meakin³

et al. 2007

Clinical Orthopaedics and Related Research

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Synthetic bone graft substitutes have been developed for impaction grafting revision hip surgery in response to concerns about the availability and potential infection risk of allograft. We performed an in vitro experiment to determine whether a synthetic porous hydroxyapatite material might improve resistance to cumulative subsidence and cyclic (elastic) movement on loading. We impacted different ratios of hydroxyapatite and allograft (0%, 50%, 70%, and 90% hydroxyapatite) into composite femoral models (eight per group) and implanted tapered, polished stems with cement. Models were loaded for 18,000 cycles on a servohydraulic materials testing machine. Migration of the femoral prostheses and the distal cement was determined using radiostereometric analysis, and cyclic movement was measured mechanically by the testing machine. Hydroxyapatite decreased overall subsidence and subsidence at the prosthesis-cement interface, but there was no difference at the cement-femur interface. This decrease may have occurred because the hydroxyapatite-containing graft was more rigid, or because it resulted in a thicker cement mantle. Cyclic prosthesis movement also was lower with hydroxyapatite. While the biologic response to porous hydroxyapatite remains to be determined, its mechanical properties appear promising.

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“…van Haaren et al 13 also reported that the mean impact forces were 12000-13000 N in the cadaver study. The measured impact forces in their studies were about five times higher than the impact force at the final rasping in our study.…”

Section: Discussionmentioning

confidence: 92%