Quantitative analysis of growth factors from a second filter using the Reamer-Irrigator-Aspirator system: description of a novel technique

An in vivo study to investigate an original intramedullary bone graft harvesting technology

BACKGROUND

Harvesting bone graft (BG) from the intramedullary canal to treat bone defects is largely conducted using the Reamer-Irrigator-Aspirator (RIA) system. The RIA system uses irrigation fluid during harvesting, which may result in washout of osteoinductive factors. Here, we propose a new harvesting technology dedicated to improving BG collection without the potential washout effect of osteoinductive factors associated with irrigation fluid. This novel technology involves the conceptual approach of first aspirating the bone marrow (BM) with a novel aspirator prototype, followed by reaming with standard reamers and collecting the bone chips with the aspirator (reaming-aspiration method, R-A method). The aim of this study was to assess the harvesting efficacy and osteoinductive profile of the BG harvested with RIA 2 system (RIA 2 group) compared to the novel harvesting concept (aspirator + R-A method, ARA group).

METHODS

Pre-planning computed tomography (CT) imaging was conducted on 16 sheep to determine the femoral isthmus canal diameter. In this non-recovery study, sheep were divided into two groups: RIA 2 group (n = 8) and ARA group (n = 8). We measured BG weight collected from left femur and determined femoral cortical bone volume reduction in postoperative CT imaging. Growth factor and inflammatory cytokine amounts of the BGs were quantified using enzyme-linked immunosorbent assay (ELISA) methods.

RESULTS

The use of the stand-alone novel aspirator in BM collection, and in harvesting BG when the aspirator is used in conjunction with sequential reaming (R-A method) was proven feasible. ELISA results showed that the collected BG contained relevant amounts of growth factors and inflammatory cytokines in both the RIA 2 and the ARA group.

CONCLUSIONS

Here, we present the first results of an innovative concept for harvesting intramedullary BG. It is a prototype of a novel aspirator technology that enables the stepwise harvesting of first BM and subsequent bone chips from the intramedullary canal of long bones. Both the BG collected with the RIA 2 system and the aspirator prototype had the capacity to preserve the BG's osteoinductive microenvironment. Future in vivo studies are required to confirm the bone regenerative capacity of BG harvested with the innovative harvesting technology.

Quantitative Analysis of Growth Factors From Cancellous Bone Graft Collected With a Reamer-Irrigator-Aspirator System From Native Long Bones Versus Previously Reamed Long Bones

OBJECTIVE

Collection of bone graft with the Reamer-Irrigator-Aspirator (RIA) system has become common practice across the field of orthopaedic surgery. While RIA bone graft is typically obtained from native long bones, grafting material can likewise be harvested from long bones that have previously undergone the placement and removal of an intramedullary nail, a process termed re-reamed RIA (RRR). The purpose of this study was to evaluate the total protein and growth factor concentrations present in native-RIA (NR) compared with RRR samples.

METHODS

NR and RRR bone grafts were collected intraoperatively with the RIA system and processed to evaluate both the aqueous and the hard tissue components. Total protein concentration and specific growth factors were analyzed using standard bicinchoninic acid and multiplex assays, respectively. Analyte levels were then normalized to the total amount of protein detected.

RESULTS

Total protein levels were comparable between NR and RRR samples for both the aqueous filtrate and the hard tissue samples. When normalized, while levels of bone morphogenic protein-2 and vascular endothelial growth factor were comparable in the hard tissue component, the aqueous filtrate from the RRR sample was found to have elevated levels of growth factors, with bone morphogenic protein-2 reaching statistical significance.

CONCLUSIONS

This study demonstrates that ample protein is found within both NR and RRR samples, with comparable or elevated levels of osteogenic growth factors found within RRR samples. Future, larger, prospective studies will be required to evaluate the osteogenic potential and clinical efficacy of NR and RRR cancellous bone grafts to validate their equivalency.

Basic Science and Clinical Application of Reamed Sources for Autogenous Bone Graft Harvest

Autologous bone graft remains the only clinically available source of graft material with osteogenic, osteoinductive, and osteoconductive properties. Although iliac crest autologous bone graft has long served as the benchmark, reamed autogenous bone graft offers several advantages. Reamed autograft has a biochemical and cellular profile that is at least equivalent, and perhaps superior, to that of iliac crest autograft. In addition, larger volumes of reamed autograft can be obtained via less-invasive techniques, giving surgeons an accessible source of mesenchymal stem cells that can be reliably and repeatedly harvested. Early clinical experience involving reamed autogenous bone graft in the management of nonunion, bone defects, and arthrodesis has been encouraging and has demonstrated the necessary properties to warrant regular consideration of reamed graft for these applications.

Assessment of Reamer Irrigator Aspirator System (RIA) filtrate for its osteoinductive potential in a validated animal model

PURPOSE

Previous studies indicate that Reamer Irrigator Aspirator (RIA) filtrate contains proteins that have the potential to stimulate bone healing. This study aimed to determine the osteoinductive capabilities of RIA filtrate in a validated in vivo model.

METHODS

With Institutional Review Board approval, RIA filtrates from 9 patients were collected. The filtrate was processed to remove cells and inorganic particles. A portion of each sample was set aside for protein analysis while the remainder was lyophilized and prepared for implantation. With Animal Care and Use Committee approval, athymic mice (n = 16; 32 hind limbs) were randomly assigned to 1 of 4 groups (n = 8 limbs per group) for percutaneous gastrocnemius muscle injection of demineralized bone matrix (DBM) (10 mg), lyophilized RIA powder (10 mg), RIA liquid (10 mg of lyophilized RIA powder in 100ul phosphate buffered saline (PBS)), or DBM (10 mg) + RIA liquid (10 mg in 100ul PBS). Radiographs were obtained 2, 4, and 8 weeks after injection. At 8 weeks, mice were sacrificed and the entire gastrocnemius muscle from each hind limb was collected and processed for histologic examination. Histological sections and radiographs were assessed for ossification/calcification. Data were compared for statistically significant (p < 0.05) differences among groups and strong (R > 0.7) correlations between outcome measures.

RESULTS

The protein composition of RIA filtrates was consistent among patients and matched previous data. For all groups, radiographic scores were significantly (p < 0.014) higher (more calcification/ossification) at 8 weeks compared to 2 weeks. Radiographic scores for the DBM and DBM + RIA liquid groups were significantly higher than RIA liquid and RIA powder at 4 weeks and 8 weeks (p < 0.019 and p < 0.049, respectively). Histologic scores were significantly (p = 0.004) higher in the DBM + RIA liquid group compared to the RIA liquid group at 8 weeks. Histologic scores showed strong correlations (r > 0.77) to radiographic scores for all groups.

CONCLUSION

RIA filtrate liquid and powder were osteoinductive in vivo with new bone formation being most abundant using a combination of DBM and RIA filtrate in this validated animal model. RIA filtrate has potential for clinical use in augmenting bone healing treatments.

More adverse events than expected in the outcome after use of the reamer-irrigator-aspirator

PURPOSE

The reamer-irrigator-aspirator (RIA) system is described as having high success rates and only few complications. The RIA was originally designed to ream the intramedullary canal in a single step prior to the placement of an intramedullary nail for femur fixation. Its purpose was to collect and evacuate marrow contents during reaming to prevent embolism into the systemic circulation. Marrow evacuation is also used to stimulate healing in nonunion fractures, segmental bone defects, and osteomyelitis. Despite the described success rates, we experienced severe adverse events. Our aim was to describe these events and point out possible complications.

METHODS

A retrospective study of all consecutive patients treated for nonunion fractures, bone defects, or osteomyelitis from October 2007 to March 2010. All patients were treated with the RIA system. We analyzed demographic characteristics, consolidation on X-rays, time from injury to healing, complications, and postoperative pain caused by the reaming procedure.

RESULTS

We included 32 patients (21 males) with an average follow-up of 277 days. Successful healing was achieved in 66 % of all patients, and 18 % suffered from postoperative pain. A complication due to the use of the RIA system was registered in 31 % of the patients. Recorded complications were bone defects, signs of lung embolism, a myocardial infarction, and fissure fractures.

CONCLUSIONS

The RIA system has benefits in the treatment of nonunion and osteomyelitis defect, but is not without risk. Meticulous surgical technique is mandatory and peroperative constant monitoring of patients and the assembled device is mandatory.

Outcomes and complication rates of different bone grafting modalities in long bone fracture nonunions: a retrospective cohort study in 182 patients

BACKGROUND

Novel bone substitutes have challenged the notion of autologous bone grafting as the 'gold standard' for the surgical treatment of fracture nonunions. The present study was designed to test the hypothesis that autologous bone grafting is equivalent to other bone grafting modalities in the management of fracture nonunions of the long bones.

METHODS

A retrospective review of patients with fracture nonunions included in two prospective databases was performed at two US level 1 trauma centers from January 1, 1998 (center 1) or January 1, 2004 (center 2), respectively, until December 31, 2010 (n = 574). Of these, 182 patients required adjunctive bone grafting and were stratified into the following cohorts: autograft (n = 105), allograft (n = 38), allograft and autograft combined (n = 16), and recombinant human bone morphogenetic protein-2 (rhBMP-2) with or without adjunctive bone grafting (n = 23). The primary outcome parameter was time to union. Secondary outcome parameters consisted of complication rates and the rate of revision procedures and revision bone grafting.

RESULTS

The autograft cohort had a statistically significant shorter time to union (198 ± 172-225 days) compared to allograft (416 ± 290-543 days) and exhibited a trend towards earlier union when compared to allograft/autograft combined (389 ± 159-619 days) or rhBMP-2 (217 ± 158-277 days). Furthermore, the autograft cohort had the lowest rate of surgical revisions (17%) and revision bone grafting (9%), compared to allograft (47% and 32%), allograft/autograft combined (25% and 31%), or rhBMP-2 (27% and 17%). The overall new-onset postoperative infection rate was significantly lower in the autograft group (12.4%), compared to the allograft cohort (26.3%) (P < 0.05).

CONCLUSION

Autologous bone grafting appears to represent the bone grafting modality of choice with regard to safety and efficiency in the surgical management of long bone fracture nonunions.

The use of Reamer Irrigator Aspirator (RIA) autograft harvest in the treatment of critical-sized iliac wing defects in sheep: investigation of dexamethasone and beta-tricalcium phosphate augmentation

Bone grafts are commonly used for the treatment of segmental bone defects and fracture non-unions. Recently, osseous particles obtained during intermedullary canal reaming (using a Reamer-Irrigator-Aspirator (RIA) device) have been evaluated as graft material during in vitro and clinical studies. The aim of this study was to evaluate and quantify new bone formation after implantation of bone graft material obtained after reaming of the tibia in a bilateral critical-sized iliac wing defect in sheep and to investigate the effect of the augmentation of this graft. A reamer bone graft alone, or after short term incubation in a dexamethasone enriched solution, and a reamer graft collected using beta-tricalcium phosphate (β-TCP) granules in the filter of the RIA collection device were compared to autologous iliac wing graft. In addition, reamer graft was combined with the cellular fraction collected from the irrigation fluid with and without short-term incubation in a dexamethasone enriched solution. It was hypothesized that the amount of physical bone in the reamer bone graft groups would be higher than the amount in the autologous iliac wing graft group and that augmentation of a reamer bone graft would increase bone formation. Three months after implantation, the amount of new bone formation (as percentage of the total defect volume) in the defects was evaluated ex-vivo by means of micro-CT and histomorphometry. The mean amount of bone in the autologous iliac wing graft group was 17.7% and 16.8% for micro-CT and histomorphometry, respectively. The mean amount of bone in all reamer graft groups ranged between 20.4-29.2% (micro-CT) and 17.0-25.4% (histomorphometry). Reamer graft collected using β-TCP granules (29.2±1.7%) in the filter produced a significantly higher amount of bone in comparison to an autologous iliac wing graft evaluated by micro-CT. RIA bone grafts added a small increase in bone volume to the 3month graft volume in this preclinical sheep model. The current model does not support the use of short-term high concentration dexamethasone for augmentation of a graft volume. If avoidance of an iliac wing graft is desirable, or a reaming procedure is required, then a RIA graft or RIA graft plus β-TCP granules are as good as the current gold standard for this model.

Complications following autologous bone graft harvesting from the iliac crest and using the RIA: a systematic review

Bone grafting is a commonly performed surgical procedure to augment bone regeneration in a variety of cases in orthopaedic and maxillofacial surgery. Autologous bone graft remains to be the 'gold standard' and the iliac crest to be the most common harvesting site. The intramedullary canal of long bones represents another potential site for large volume of autologous bone graft harvesting and is recently being used as an alternative donor site. However, harvesting of autologous bone graft is associated with morbidity and a number of complications. The aim of this systematic review was to collect and summarise the existing data on reported complications after harvesting autologous bone from the iliac crest (anterior and posterior) and the long bone intramedullary canal using the RIA device. We searched the PubMed Medline and Ovid Medline databases, from January 1990 to October 2010, to retrieve all relevant articles. A total of 92 articles (6682 patients) were included in the analysis. Overall, the complication rate following RIA was 6% (14 complications in 233 patients) and 19.37% after iliac crest bone graft harvesting (1249 complications in 6449 patients). The rate of each of the reported complications was assessed and, when the donor site was properly documented, comparison within the anterior and posterior iliac crest donor sites was performed. Although the difference of the overall morbidity rates between the two harvesting sites was not statistically significant (p=0.71); the rates of certain complications were found to significantly differ when anterior or posterior iliac crest was used. The rates of infection (p=0.016), haematoma formation (p=0.002), fracture (p=0.017), and hyperthrophic scar (p=0.017) were significantly higher when the donor site was the anterior iliac crest compared to the posterior iliac crest; whereas the rates of chronic donor site pain (p=0.004) and sensory disturbances (p=0.003) were significantly lower. The incidence of bone graft harvesting related complications can be reduced further if certain principles are followed depending on the performed harvesting methods; but overall the use of RIA device as harvesting method seems a promising alternative with a low complication rate.

RIA use in a community orthopedic trauma practice: applying technology, respecting biology

The RIA (Reamer Irrigator Aspirator) device is an incredibly powerful tool. It can be used to obtain biologically active tissue for healing at local or distant sites. Additionally, it can be used to lower the negative bioburden of disease and even to assist in diagnosis. As with any powerful tool, it should be used with detailed pre-planning and great respect. Once properly understood and implemented, the device can be used in many ways: