Impaction allografting—The effect of impaction force and alternative compaction methods on the mechanical characteristics of the graft

Abstract

Revision total hip replacement with impaction allografting has an attractive potential for restoring bone stock, however, fractures and implant migration remain problematic. Postoperative graft deformation is believed to contribute to migration. Under compressive loading, the fluid in the graft takes up the load initially through fluid pressure that dissipates over time. Given the short duration of an impaction, we proposed two novel graft compaction techniques that allow more time for fluid flow: holding a compression force constant for 90 s (creep technique), and cycles of compressing the graft to a given force and then holding the displacement constant (cyclic relaxation technique). This study examined the effect of the impaction force on the density and mechanical characteristics of the graft, and explored the potential benefit of the proposed alternative compaction techniques. Increasing the impaction force from "low" to "high" increased graft density by 41%, and this translated to stiffness and shear strength increases of 93 and 164%, respectively. The creep technique improved the stiffness and shear strength by 14 and 16%, respectively, when compared with impaction, while the cyclic relaxation technique did not improve the mechanical properties. Although the creep technique could potentially provide a lower risk of intraoperative fracture over the use of larger impaction forces, any clinical benefit of the creep technique warrants further investigation. Our results point to the importance of maximizing impaction forces in impaction allografting surgery.

Effect of synthetic bone replacement material of different size on shear stress resistance within impacted native and thermodisinfected cancellous bone: an in vitro femoral impaction bone grafting model

“…Heterogeneity of the cancellous bone and differences of the impaction technique have to be considered regarding mechanic properties of impacted bone graft (Albert et al 2008 ; Fosse et al 2006b , 2006c ; Frei et al 2004 ; Phillips et al 2006b ) since the number of impaction procedures seemed to be related to the quality of bone (Ahmed et al 2018 ; Bavadekar et al 2001 ; Fölsch et al 2018 ; Oakley and Kuiper 2006 ). The necessary number of impaction impulses for thermodisinfected bone appeared less compared with native bone and fluid needed to be removed from the top of the native specimens following impaction (Table 1 ).…”

“…Reduced movement within the impacted bone graft distal (Table 2 ) might be related to different distribution of energy during femoral impaction grafting (Fosse et al 2006a ; Frei et al 2005a , 2005b ). For particles being more prone to viscoplastic behavior than native bone like processed thermodisinfected bone the impaction force seems more important for the impaction than the particle size (Albert et al 2008 ). Native and thermodisinfected bone particles of different size achieved comparable distribution of bone graft assuming different mechanical properties (Cornu et al 2009 ; Fölsch et al 2018 ).…”

“…A different effect on the impaction behavior of native and thermodisinfected cancellous bone should be considered since less change of mechanic properties of impacted bone due to smaller particles was shown according to clinical studies (Cornu et al 2003 ; Gehrke et al 2013 ). In the early phase of impaction fluid is part of transfer of load followed by viscoelastic and viscoplastic deformation of bone (Albert et al 2008 ). This might be relevant regarding different content of water within impacted bone graft and the removal of fluid from native specimens (Fölsch et al 2018 ).…”

Revision Total Hip Arthroplasty with Femoral Impaction Bone Grafting

“…Initial stem subsidence is associated with inadequate cement pressurisation. 13 Early subsidence of polished, double-tapered, collarless stems varies from 2 to 10 mm, and clinical signs of failure were mostly absent. 4,9,14 In a series of 226 revision THAs with IBG, 15 massive subsidence was associated with higher preoperative Endo-Klinik grade bone loss.…”

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

“…This then offers the possibility of employing computer based stress analysis techniques to help inform experimental and clinical observations (e.g. Phillips et al [45], Lunde & Skallerud [25], Albert et al [46])…”