gms | German Medical Science

Objectives: This research details an innovative concept for the incremental extraction of intramedullary (IM) bone grafts using an intuitive aspiration prototype device. Initially, bone marrow is harvested using an aspirator (first method), and this is followed by a process termed the reaming-aspiration method (R-A method) involving repetitive reaming using standard intramedullary reamers while simultaneously aspirating the fragmented endosteal bone chips. Both methods together are forming the aspirator+reaming-aspiration concept (ARA, introduced in [1]). In a recent study ([2]), both the Reamer-Irrigator-Aspirator (RIA) 2 system (gold standard for IM bone graft harvesting, RIA2 group) and the ARA concept were associated with only minor fat intravasation, coagulopathic reactions and pulmonary fat embolism. However, perioperative blood and systemic inflammation have not yet been studied in comparison and based on the preliminary studies we hypothesize no difference between the groups. The aim of the study is therefore to assess whether RIA 2 system is comparable to the ARA concept in terms of blood loss and systemic inflammatory response.

Methods: Intramedullary bone graft was harvested from intact femora of 16 Merino sheep (age: 1–2 years). Perioperatively blood loss (drop in hemoglobin, HB) and systemic inflammatory response (interleukins (IL)-1ß, 6, 8 and 10) were monitored by taking blood samples at different time points up to 4 hours post-surgery. Ethical approval was obtained from the Queensland University of Technology (QUT) Animal Ethics Committee (UAEC, approval number 2000000593). A linear mixed model (LMM) with restricted maximum likelihood estimation (REML) was used (R programming software, version 4.0.2) for statistical analysis and a significance level of p = 0.05 was chosen.

Results and conclusion: Eight sheep were assigned to each of the RIA 2 and ARA groups, with an averageisthmus diameter of 12.21 ± 0.37 mm and12.29 ± 0.41 mm respectively (p = 0.68). In the RIA 2 group, a total of 73 reaming steps were carried out, averaging 9.13 ± 0.84 per sheep. Similarly, in the ARA group, 74 reaming steps were performed, averaging 9.25 ± 0.71 per sheep (p = 0.75). Only minor blood loss occurred and there was no significant difference in blood loss volume between groups (p = 0.55). Furthermore, there was no difference in inflammatory response assessing IL-2, IL-6, IL-8 and IL-10 comparing the ARA with the RIA2 group (all p > 0.05). In conclusion, comprehensive testing of the novel IM ARA bone graft harvesting concept showed that the harvesting concept was equivalent to the gold standard RIA 2 system in terms of blood loss and systemic inflammatory response. This work paves the way for further development of a promising innovative alternative technology for the harvesting of IM bone marrow and bone chips, which has the potential to transform the approach to harvesting graft material.