Autologous bone graft has been used in the treatment of complex bone defects for more than a century. Morbidity associated with the harvest of this bone graft has led orthopaedic surgeons to seek alternative therapies in the treatment of long bone non-unions. The aim of this study was to determine whether the use of demineralised bone matrix as a bone healing adjunct improves clinical outcomes in adult patients with long bone non-union. A systematic search was carried out of the peer-reviewed English language literature to identify all relevant studies. The search strategy returned a total of 47 studies. Five of these studies were relevant to the research question. The studies were critically assessed and where appropriate combined in a meta-analysis. 4 non-comparative studies and one comparative study were reviewed. An overall estimate of the rate of union for the five studies was 86% (95%CI: 71–94%). The one comparative study demonstrated the relative risk (RR) of healing was not significantly better than in patients treated with autologous bone graft; RR=1.03 (95%CI 0.96–1.12). There are limited data to support the use of demineralised bone matrix in the treatment of long bone non-union. Demineralised bone matrix is likely to be similarly effective to other treatments in the management of non-union. This study confirms the clinical and ethical requirements to proceed with a randomised controlled trial to test the effectiveness of this intervention

The purpose of this study was to understand the effects of terminal sterilisation and residual calcium on human demineralised bone matrix (DBM) in ectopic bone formation in nude rat.

The intramuscular implantation of human DBM prepared by the Queensland Bone Bank (QBB) from four donors into eight male athymic rats was used to assess osteoinductivity. The DBM contained different levels of residual calcium and treated with or without gamma-irradiation at 11kGy. At 6 weeks post-implantation, calcium deposition was assessed by manual palpitation and radiological imaging. Tissue morphology and cellular interactions was analysed using various histological staining methods whilst protein expression of anabolic and catabolic biomarkers were examined through immunohistochemistry. All results were then analysed in qualitative, semi-quantitative and quantitative manners and tested for statistical significance.

Bone formation was observed in all specimens at the gross level. This was confirmed by histology which revealed bony capsules surrounded by soft tissue in the muscle pockets and differences in tissue components. On a cellular level, variations in osteoclast expression were found between the two groups as well as amongst individual donors through statistical analysis which resulted in an imbalance of the expression of anabolic and catabolic markers. Furthermore, a positive relationship between residual calcium and new bone formation in gamma irradiated DBM samples was found. To date, no studies have compared the effect of calcium in gamma irradiated DBM.

Our results suggest that gamma irradiation even at low doses and residual calcium may affect new bone formation. Taken together, this study stresses the importance of selecting ideal conditions for graft processing and the need to identify an optimal level of irradiation and remaining calcium levels that confers a balance between osteoinductivity and sterility.

Introduction. Demineralised Bone Matrix (DBM) is widely used in Orthopaedics and dentistry as a bone graft substitute and may be used to augment bone formation in load bearing applications. In this study we examine the effect of gamma irradiation and freeze drying on the tensile strength of Demineralised Cortical Bone (DCB). Methods. Tibias were harvested from mature ewes and cut into bony strips. Demineralisation was done using 0.6M HCL and confirmed by X-ray. Specimens were washed until a pH of 7.0 +/_ 0.2 was achieved in the washing solutions. Specimens were allocated into 4 groups; group (A) non freeze dried non gamma irradiated, group (B) freeze dried non gamma irradiated, group (C) non freeze dried gamma irradiated mention the level of gamma irradiation and group (D) freeze dried and gamma irradiated. The maximum tensile force and stress were measured. Statistical analysis using the Mann-Whitney U test was carried out. Results. The Median of maximum tensile force for group (A) was 218N, group (B) was 306N, group (C) was 263N and for group (D) was 676N. Group (D) results were statistically higher (p=< 0.05) compared to group (A) and (C), while there was no statistical significance compared to group (B). Conclusion. Previously published studies suggested the possibility of using DCB as ACL graft substitute. We examined the effect of gamma radiation as the most common sterilisation technique in medical field and the freeze drying as a possible technique for long term storage on the tensile strength of the DCB. Freeze drying significantly increases the tensile strength of the DCB while gamma irradiation has no significant effect. Our results indicate that freeze dried gamma irradiated DCB can be used as a ligament substitute

Aim. To compare a variety of commercially available bone graft substitutes (BGS) in terms of promoting adherence, proliferation and differentiation of osteoprogenitor cells. Materials and methods. A fixed number of porcine mononuclear cells obtained from cancellous bone of the proximal femur was mixed with a standard volume of BGS and then cultured for one week in media followed by two weeks in osteogenic media. BGS included commercially available β-Tricalcium Phosphate (□-TCP), highly porous β-TCP, Hydroxyapatite/Tricalcium phosphate composite, calcium sulphate (CS), Hydroxyapatite (HA), Demineralised bone matrix (DBM), polygraft, and polymers (PGA, PLGA). Staining for live/dead cells as well as scanning electron microscopy (SEM) were carried out on all samples to determine viability and cellular binding. Further outcome measures included alkaline phosphatase assays with normalisation for DNA content to quantify osteogenic potential. Negative (BGS without cells) and positive (culture expanded osteoprogenitors) control experiments were carried out in parallel to validate the results. Results. Live/dead and SEM imaging showed higher cellular viability and attachment with β-TCP than with other BGS. In the experimental setup the average alkaline phosphatase activity in nmol/ml (normalised value for DNA content in nmol/μg DNA) per sample was 657.58 (132.03) for β-TCP, 36.22 (unable to normalise) for calcium sulphate, 19.93 (11.39) for the HA/ TCP composite, 14.79 (18.53) for polygraft, 13.98 (8.15) for the highly porous β-TCP, 5.56 (10.0) for PLGA, 3.82 (3.8) and for HA. It was not possible to analyse data for either DBM or PGA. Conclusion. Under theses experimental conditions, β-TCP has apparent favourable characteristics in terms of maintaining viability of osteoprogenitor cells and allowing proliferation and differentiation. Further work will be carried out to characterise the effect that BGS have on osteoprogenitor cells