Biological and mechanical changes of the bone graft–cement interface after impaction allografting

Abstract

In impaction allografting, the host bone interface may consist of morsellized allograft alone or as a composite with bone cement. The objective of this study was to investigate the temporal changes in the interface for these two materials in a rat bone chamber model. To simulate the impaired endosteal circulation after impaction allografting, bone chambers were tightened bilaterally to the endosteal surfaces of proximal tibiae of mature rats and filled with pure allograft or cement/allograft composite. The cement/allograft composite-host bone interface strength was significantly higher at 3 weeks and was higher than the allograft construdt failure strength. Limited allograft, but extensive periosteal remodeling, was observed at 3 weeks which resulted in a significantly increased cortical porosity and cortical thickness. The allograft porosity decreased significantly at 6 weeks indicating extensive remodeling of the allograft bone. Little or no remodeling of the allograft particles in the cement was found. At 6 weeks a new medullary canal was formed, and the endosteal cortex was partially absorbed. Endosteal absorption resulting in medullary canal widening in revision THR may be responsible for clinically unstable stems after impaction allografting.

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

“…Other mechanisms such as cement fatigue, 5 graft incorporation/fibrous invasion, 31,32 and cancellization of the femoral canal 33 are also suspected to play a role in implant stability, while previous studies also point to the importance of cement contact with the endosteum. 34,35 Nonetheless, clinical studies have shown that a substantial amount of subsidence develops in the early postoperative days: more than 1 mm subsidence was often observed within the first 3 months after surgery 36,37 and more than half of the subsidence observed at 6 weeks was seen typically within the first 2 weeks.…”

Use of mesenchymal stem cells to enhance bone formation around revision hip replacements

“…16 However, Piert et al 17 used Dynamic [18F] fluoride ion positron emission tomography (PET) to investigate the metabolic activity of allograft and concluded that the metabolic level was increased initially after surgery but decreased over time indicating allograft resorption. An animal study by Frei et al 18 also showed significant allograft resorption at 6 weeks, resulting in medullary canal widening and an unstable implant.…”

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

“…8 ). 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 ).…”

“…Cement intrusion in the distal two thirds of impacted bone graft seemed mainly determined by graft permeability and appeared reduced distal in thermodisinfected compared with native cancellous bone (Fölsch et al 2018 ; Frei et al 2004 , 2006 ) which might reflect reduced porosity of impacted thermodisinfected cancellous bone in the distal region (Fig. 8 ) (Frei et al 2005b ) since increased air in the proximal region of thermodisinfected cancellous bone was shown (Fölsch et al 2018 ). This could be related to differences of micromovement at the proximal and distal point of measurement in the thermodisinfected bone specimens compared with native bone (Ohashi et al 2009 ) (Table 2 ).…”

“…Less micromovement at the distal point of measurement was a consistent behavior of impacted native and thermodisinfected cancellous bone also being supplemented with small and large granules (Table 2 ). The cement penetration into the bone allograft and the cement volume resulting in an increased surface were found higher for native than for thermodisinfected cancellous bone (Fölsch et al 2018 ; Frei et al 2005b ). The influence of increased density on primary stability of impacted bone and the penetration of cement into the bone graft have to be considered.…”