Hiang Boon Tan

The systemic inflammatory response following femoral canal reaming using the reamer-irrigator-aspirator (RIA) device

We evaluated the peripheral release of inflammatory mediators after femoral fracture and subsequent intramedullary reaming using the RIA reamers. IL-6 was elevated after trauma, and reaming with RIA induced a measurable second hit response. However, despite a higher ISS, the levels of IL-6 in the RIA group were similar to the levels measured in a group of patients where reaming of the femoral canal was performed using conventional reamers. There was one death related to fat embolism syndrome in the conventional reamers group. However, the overall incidence of complications was low and similar between the 2 groups of studied patients. In polytrauma patients, large scale studies are desirable to evaluate further the immuno-inflammatory response using the RIA reamers prior to the instrumentation of the femoral canal.

Examining the Feasibility of Clinical Grade CD271+ Enrichment of Mesenchymal Stromal Cells for Bone Regeneration

Introduction Current clinical trials utilize mesenchymal stromal cells (MSCs) expanded in culture, however these interventions carry considerable costs and concerns pertaining to culture-induced losses of potency. This study assessed the feasibility of new clinical-grade technology to obtain uncultured MSC isolates from three human intra-osseous tissue sources based on immunomagnetic selection for CD271-positive cells. Materials and Methods MSCs were isolated from bone marrow (BM) aspirates or surgical waste materials; enzymatically digested femoral heads (FHs) and reamer irrigator aspirator (RIA) waste fluids. Flow cytometry for the CD45−/lowCD73+CD271+ phenotype was used to evaluate uncultured MSCs before and after selection, and to measure MSC enrichment in parallel to colony forming-unit fibroblast assay. Trilineage differentiation assays and quantitative polymerase chain-reaction for key transcripts involved in bone regeneration was used to assess the functional utility of isolated cells for bone repair. Results Uncultured CD45−/lowCD271+ MSCs uniformly expressed CD73, CD90 and CD105 but showed variable expression of MSCA-1 and SUSD2 (BM>RIA>FH). MSCs were enriched over 150-fold from BM aspirates and RIA fluids, whereas the highest MSC purities were obtained from FH digests. Enriched fractions expressed increased levels of BMP-2, COL1A2, VEGFC, SPARC and CXCL12 transcripts (BM>RIA>FH), with the highest up-regulation detected for CXCL12 in BM (>1300-fold). Following culture expansion, CD271-selected MSCS were tri-potential and phenotypically identical to plastic adherence-selected MSCs. Discussion A CD271-based GMP-compliant immunomagnetic selection resulted in a substantial increase in MSC purity and elevated expression of transcripts involved in bone formation, vascularisation and chemo-attraction. Although this technology, particularly from RIA fluids, can be immediately applied by orthopaedic surgeons as autologous therapy, further improvements in MSC purities and pre-clinical testing of product safety would be required to develop this process for allogeneic applications.

MRI appearances of the femur following bone graft harvesting using the Reamer-Irrigator-Aspirator.

The reamer-irrigator-aspirator is increasingly being used to harvest autologous bone graft from the femur. The purpose of this study was to investigate the extent of neo-vascularisation and new bone formation that occurs within the medulla following the procedure, and determine if new bone formation would potentially allow a repeat bone harvest in those individuals subsequently requiring further bone graft. Eleven patients who had undergone femoral bone harvest were examined with MRI. The nature of the tissue within the medulla and the extent of neo-vascularisation were assessed. MRI was performed between 3 months and 28 months following bone graft harvest, mean 14 months. Intense vascularisation of the endostial cortical surface and neo-vascularisation of the haematoma within the canal occurred as soon as 3 months following bone harvest. From as early as 14 months the tissue was replaced by normal intramedullary bone. The formation of new bone within the medullary canal gives the potential for a repeat reaming, should further bone graft be required at a later date.

The Timing of Drug Administration for Thromboprophylaxis Following Orthopaedic Surgery: Evidence and Controversies Related to Treatment Initiation and Duration

Patients undergoing major orthopaedic surgery of the lower extremities or spine are at increased risk of venous thromboembolism (VTE). Although consensus exists as to the need for routine thromboprophylaxis in high risk patients, some aspects of this approach, such as the timing of the first dose and overall duration of the anticoagulation regimen, are subject to debate. Reviewing the available literature, there appears to be little evidence to support initiation of thromboprophylaxis more than 12 hours before surgery. Perioperative thromboprophylaxis (2 hours pre to 6 hours post -op) has been associated with an increased risk of bleeding complications whilst initiating prophylaxis more than 12 hours after surgery appears to increase the incidence of subsequent thromboembolic complications. Overall evidence would appear to support initiation of thromboprophylaxis 6 to 9 hours postoperatively, though further confirmatory studies investigating this variable in isolation would be useful to guide clinical decision making. Although evidence exists supporting extended duration thromboprophylaxis after major orthopaedic procedures, further evidence is required, using clinically important end points, prior to adoption of such an approach in all patients. Stratification of prophylaxis duration, based on risk factors for thromboembolic or bleeding complications, would seem a more rational approach than strict adherence to guidelines.

Simple elbow dislocations: Management, direct medical cost and clinical outcome

Objectives To evaluate management, direct-medical-costs and clinical outcome profile of a large trauma unit with respect to simple elbow dislocations. Methods All simple elbow dislocations that were defined as not requiring acute surgical intervention, post-reduction, were considered between Jan-2008 and Dec-2010. Inclusion criteria consisted of age greater than 13; absence of major associated fractures, successful closed reduction, and follow-up as an outpatient. The management of these patients was classified in terms of immobilisation time into: short ( 3weeks). Direct-medical-costs were calculated based on current tariff rates associated with radiology, admission, theatre time (for reductions and recovery) and outpatient attendances. Clinical outcome was evaluated with respect to complications, secondary procedures, and time before discharge from clinic. Results Of 81 patients in total, 6% required reduction in theatre, 17% admission, 9% were referred to a specialist or had a complication and 42% DNA their final appointment. The mean length-of-immobilisation was 2.25weeks (range 0–6weeks). The median direct-medical-cost was £893 per patient (range £418-£2,693). The median duration of patients9 engagement with hospital services was 57days (range 3–831). There was no statistically significant relationship between length-of-immobilisation and time-before-discharge (p=0.42), or associated direct-medical-cost (p=0.586). In terms of clinical outcome the prolonged immobilisation group had a statistically significant worse outcome in comparison to the short (p=0.30) and the standard (p=0.01). The comparison between standard immobilisation and short resulted in a marginally (p=0.08) significant advantage of the first. Conclusion Prolonged elbow immobilisation is generally associated with increased stiffness and a higher rate of complications. For simple elbow dislocations time-to-mobilisation was variable, as well as the mode of follow-up. The use of standardised protocols of treatment is essential in these type of injuries that are usually managed in an outpatient basis, to minimise the variability between clinical teams, improve outcome, and minimise costs