Aims

Platelet-rich plasma (PRP) intra-articular injections may provide a simple and minimally invasive treatment for early-stage knee osteoarthritis (OA). This has led to an increase in its adoption as a treatment for knee OA, although there is uncertainty about its efficacy and benefit. We hypothesized that patients with early-stage symptomatic knee OA who receive multiple PRP injections will have better clinical outcomes than those receiving single PRP or placebo injections.

Hematopoietic stem cells (HSCs) reside within a specialised niche area in the bone marrow (BM). They have tremendous clinical relevance, although HSC expansion and culture ex vivo is not currently possible, reducing BM transplant success. This project expands a novel 3D MSC niche model developed in our lab to include HSCs.

MSCs were loaded with green fluorescent magnetic iron oxide (FeO₃) nanoparticles (200 nm diameter) at a concentration of 0.1 mg ml⁻¹, and incubated for 30 min over a magnet to enhance cellular uptake. The cells were washed, detached and resuspended, then transferred to a plate with magnets above. Spheroids formed within hours and were implanted into 2 mg ml⁻¹ collagen gel. HSCs were loaded with nanoparticles via incubation with suspension, and then introduced to the gel containing the spheroid. Immunostaining, BrdU and Calcein/ ethidium homodimer viability assays were performed to characterise the cells.

Cells in both monolayers and spheroids remain viable up to 7 days in culture. MSCs in monolayers and spheroids were stained with antibodies for: STRO-1, an MSC marker; SDF-1 (CXCL-12), a secreted HSC homing factor; and nestin, a marker for HSC-supportive MSCs in vitro. MSCs in spheroids retain a higher level of expression of all three for 7 days compared to MSCs in monolayers. BrdU assay results show that the MSCs are more quiescent in spheroids compared to monolayers.

Proof of principle studies are promising for the success of the proposed niche model. MSCs express a higher level of MSC markers and retain quiescence when they are in spheroids as compared to monolayers. They also express a higher level of HSC niche factor SDF-1α, which facilitates HSC migration and retention.

Despite the publication of numerous studies, controversy regarding the non- operative treatment of type II dens fractures remains. The halo-thoracic vest (HTV) and cervical collar are the most commonly used devices. We sought to compare the outcomes of patients managed with these devices in terms of non-union risk factors and associated complication rates.

This study was a retrospective review of adult patients with type II dens fractures treated non-operatively at a level one trauma centre between 2001 and 2007. The patients were identified using a hospital trauma database. Each patient included in the study had a minimum follow up of six months. Patient medical records and imaging studies were reviewed. Union was defined as stable fibrous union or bony union, measured at three months. A p-value of < 0.05 was considered statistically significant.

Sixty-seven patients were included. Thirty-five patients were treated using a HTV and 32 with a collar. Non-union was found to be associated with increased time in HTV or collar (p = 0.011) and with a mechanism of injury involving a low fall (p = 0.008). In addition, the proportion of patients with stable union at three months was 60% for the HVT group versus 35% for the cervical collar group (p = 0.10). There were trends to support an increased risk of non-union with a patient age of greater than or equal to 65 years at the time of presentation (p = 0.13) as well as with a fracture displacement of greater than or equal to 2 mm at time of presentation (p = 0.17). Clinically significant complications of the HTV were of greater prevalence than those experienced by collar patients. Sixty percent of HTV patients suffered one or more complications compared with 6% of collar patients.

We were unable to demonstrate any clear advantage or disadvantage of either device. Further investigation of mortality would be beneficial, particularly in the patient group injured with a mechanism involving a low fall (which tends to include more elderly patients).