Infections after bone allograft surgery: a prospective study by a hospital bone bank using frozen femoral heads from living donors

Evaluation of the efficacy of using dental pulp graft in the healing of the alveolar bone after impacted canine extraction: a prospective cohort study

Summary

The purpose of this study was to evaluate the radiographic density of the alveolar bone of the maxilla after extraction of the impacted canines and using the pulp tissue as an autogenous graft.

Materials and methods

This prospective cohort study recruited 14 patients (8 females and 6 males) between 2021 and 2023, with an average age of 35 years. All participants had palatally impacted maxillary canines. The impacted teeth were extracted surgically. The extracted teeth were then used for autogenous grafting. The pulp tissue was removed, cut into small pieces, and placed on an absorbable gelatin sponge before being inserted into the extraction socket. The wound was subsequently closed meticulously. After 4 months, the bone density was assessed radiographically using the Hounsfield Scale on cone beam computed tomography scans.

Results

After 4 months, the mean radiographic bone density value in the extraction area was (652.77 ± 56.13 HU), while the average density of the original bone was (659.7 ± 39.6 HU).

Conclusions

Within the limits of this study, dental pulp tissue can be used to restore bony defects of the alveolar bone in the maxilla. However, further research is needed to confirm these findings.

Clinical and Biological Validation of an Allogeneous Cancellous Bone Block for Alveolar Maxillary Ridge Reconstruction: A Case Series

This exploratory case series clinically and histologically investigated the performance of allogeneic cancellous freeze-dried bone allograft (FDBA) bone blocks (Maxgraft®) for the lateral augmentation of local alveolar defects in the posterior maxilla as part of two-staged implant therapy. Five patients receiving eight implants 5 months after block augmentation with a follow-up period of up to 3 years were documented and analyzed. Horizontal alveolar dimensions before and 5 months after block augmentation were quantified using CBCT. Radiographic marginal bone level changes were quantified at implant placement, loading, and 1 year post-placement. Graft integration and resorption were histologically qualitatively evaluated from core biopsies retrieved at implant placement. Block augmentations resulted in a pronounced horizontal median bone gain of 7.0 (5.5 to 7.8) mm. Marginal implant bone levels in block-augmented bone remained constant over the 1 year follow-up period. Block grafts appeared histologically well integrated. Histologic analysis also revealed signs of progressive resorption and new bone formation at the lateral aspects of the grafts. The results of this case series support using Maxgraft® cancellous FDBA blocks as suitable materials for the lateral augmentation of local alveolar defects.

Exploring the Role of Intraoperative Positive Culture of Allograft Bone in Subsequent Postoperative Infections among Donors and Recipients in Bone Bank Processing

BACKGROUND

Allografts have been frequently used in orthopedic procedures. The purposes of this study were to evaluate the discard rates and bacterial contamination of a bone bank, and to assess the clinical outcomes of recipients with bacterial culture-positive donor allografts.

METHODS

We retrospectively reviewed 1764 allografts which were harvested from living donors and stored in a bone bank from 2018 to 2022. The donors whose allografts displayed bacterial contamination at retrieval of the primary hip or knee arthroplasty were followed for microbiology and subsequent prosthetic joint infection analysis. The infected pathogens, antibiotic treatment and subsequent infection were reviewed for the intraoperative positive culture group.

RESULTS

The discard rate was 17%, and the bacterial contamination rate of bone retrieval was 2.15%. Thirty-eight allografts at retrieval displayed confirmed bacterial growth, and 37 patients did not reveal infective signs at 6 months follow-up. A total of 1464 allografts were stored and implanted, among which 28 allografts (1.91%) were confirmed to be positive for bacterial growth and 13 cases (0.89%) were confirmed as surgical site infections.

CONCLUSIONS

Our results validate the suggestion that our bone bank system performs good quality monitoring to eliminate the risk of dissemination of viral and bacterial diseases and to decrease surgical site infection after allograft implantation. By ensuring aseptic conditions and contamination-reducing strategies during harvesting and thawing, the allografts can be safely stored and implanted while limiting bacterial contamination. Our findings confirm that the intraoperative positive cultures of allografts did not contribute to subsequent postoperative surgical site infection in donors and recipients.

Twenty-four-month interim results from a prospective, single-arm clinical trial evaluating the performance and safety of cellular bone allograft in patients undergoing lumbar spinal fusion

BACKGROUND

Autologous bone grafts are the gold standard for spinal fusion; however, harvesting autologous bone can result in donor site infection, hematomas, increased operative time, and prolonged pain. Cellular bone allografts (CBAs) are a viable alternative that avoids the need for bone harvesting and may increase fusion success alone or when used as an adjunct material. The present study examined the efficacy and safety of CBA when used as an adjunct graft material to lumbar arthrodesis.

METHODS

A prospective, single-arm, multicenter clinical trial (NCT02969616) was conducted in adult subjects (> 18 years of age) undergoing lumbar spinal fusion with CBA graft (CBA used as primary (≥ 50% by volume), with augmentation up to 50%). Radiographic fusion status was assessed by an independent review of dynamic radiographs and CT scans. Clinical outcomes were assessed with the Oswestry Disability Index (ODI), and Visual Analog Scales (VAS) score for back and leg pain. Adverse events were assessed through the 24-month follow-up period. The presented data represents an analysis of available subjects (n = 86) who completed 24 months of postoperative follow-up at the time the data was locked for analysis.

RESULTS

Postoperative 24-month fusion success was achieved in 95.3% of subjects (n = 82/86) undergoing lumbar spinal surgery. Clinical outcomes showed statistically significant improvements in ODI (46.3% improvement), VAS-Back pain (75.5% improvement), and VAS-Leg pain (85.5% improvement) (p < 0.01) scores at Month 24. No subject characteristics or surgical factors were associated with pseudoarthrosis. A favorable safety profile with a limited number of adverse events was observed.

CONCLUSIONS

The use of CBA as an adjunct graft material showed high rates of successful lumbar arthrodesis and significant improvements in pain and disability scores. CBA provides an alternative to autograft with comparable fusion success rates and clinical benefits.

TRIAL REGISTRATION

NCT02969616.

Transition from Secondary Blood Test to Nucleic Acid Amplification for Safe Allograft Transplantation

Background

Given the incubation period of viral diseases, a secondary blood test should be performed at least 3–6 months after the first test to ensure the safety of allogenic bone grafts obtained from living donors in some tissue banks. The allograft is discarded if a secondary blood test was unavailable. The secondary blood test can be replaced with a nucleic acid amplification test (NAT) to reduce the discarded allograft. The purpose of this study was to analyze the comparative efficiency of secondary blood test and NAT to determine the donor suitability of allogenic bone grafts.

Methods

Allogenic bones were retrieved from 452 living donors between January 2013 and December 2019. A secondary blood test was conducted in 182 patients and NAT was performed in 270 patients. The average age of donors was 69 years (range, 33–87 years). They included 86 men and 366 women. The initial blood tests including hepatitis B, hepatitis C, AIDS, and syphilis were conducted before retrieving grafts. The results were analyzed after the secondary blood test was performed at least 3 to 6 months after the first test because of the incubation period of the viral diseases. NAT was performed within 2 months after the first blood test.

Results

Sixty-seven of the 452 cases (14.8%) were discarded. In the secondary blood test group, 50 out of 182 cases (27.4%), and in the NAT group, 17 out of 270 cases (6.3%) were discarded. None of the 132 donors tested positive in the secondary blood test after testing negative in the first test.

Conclusions

It is extremely rare that the secondary blood test yields positive results in donors who tested negative in the initial test. However, quite a few grafts are discarded only because the secondary blood test is not available. In terms of economics and ethics, the secondary blood test may not be necessary or if required, a single test such as NAT for infectious diseases may be performed to determine donor suitability of allogenic bone.

Infection and utilization rates of bone allografts in a hospital-based musculoskeletal tissue bank in north India

BACKGROUND

The bone bank unit of interest in this article was established in January 2018, in a tertiary care teaching institute of north India. Aim of this article is to describe the sources of allografts obtained, discard rates of allografts and infection rates in the recipients after use.

MATERIAL AND METHODS

All the relevant details of donors and recipients were maintained, and donors were screened for standard inclusion and exclusion criteria before obtaining the grafts. Aerobic culture was performed before storage and just prior to use. Samples with incomplete documentation, incomplete donor screening or positive cultures were discarded. Data on surgical site infection in recipients was collected from hospital records retrospectively. Initially ELISA based serological tests were used for screening. Donor has to undergo these tests again after 6 months to account for the window period of proliferation of viruses. Nucleic acid amplification tests (NAAT) for these viral agents were introduced in the hospital in May 2018.

RESULTS

Allografts from a total of 196 donors were obtained in the bone bank over 2 years. Major source of bone was femoral heads harvested during total hip arthroplasty or hemi-arthroplasty. 44(22.4%) grafts had to be discarded. 95 allografts were used in 88 patients during this time. Most common indication for use was surgery for bone tumors (40%), followed by complex primary or revision arthroplasty (30.5%). Three (3.4%) recipients developed deep infection postoperatively.

CONCLUSION

Frozen allograft bone from hospital based bone banks is a reliable source of allografts. When meticulous precautions for sterility are followed, risk of infection is low. Monitoring of such bone banks should fall within a framework of the local legislature. Incomplete documentation is the major reason for wastage of the samples obtained. NAAT may be useful in screening of donors, as it reduces the wastage and the holding time of the allografts.

The quality assessment of the University hospital bone bank in Central Serbia: the second audit after fourteen years

We analyzed the prevalence and predisposing factors for the overall rejection rate after retrieval of 267 fresh femoral head allografts over the past 7 years. The present study aimed to assess the quality system of institutional bone banking that can provide high-standard allografts with a low infection rate. Retrospective analysis of bone banking from June 2013 to December 2019 was conducted on 267 donors and 153 recipients. Of the 267 donated femoral heads, 74 were rejected, giving an overall rejection rate of 27.71%. The leading cause of allograft rejection was the inability to perform serology tests due to donor death; the absence of serological tests itself, and the donor refusal to perform the serology 6-month retest in 42 donors (15.72%). At retrieval, 12 allografts were positive, giving an overall contamination rate of 4.49%. Seven (2.62%) of the 267 allografts failed the blood screening tests. Thirteen allografts (4.86%) were discarded because of suspected damage to the packaging or disuse during surgery. An infection rate of 1.30% was found following transplantation. Over the past 7 years of bone banking, our results show that the overall rejection rate and the allograft-related infection rate correlate with international standards. The leading cause of allograft rejection was the inability to perform serology tests due to donor death and their refusal to perform the serology retests. Besides stringent aseptic allograft handling, donor motivation to participate in bone banking is extremely important for its efficient functioning.

[A clinical radiological score for femoral head grafts : Establishment of the Tabea FK score to ensure the quality of human femoral head grafts]

INTRODUCTION

Transplantation of cancellous tissue from human femoral heads (FK) is an established method in the reconstruction of bony defects in orthopedic and trauma surgery. Standardized rating systems with respect to the morphological quality of this tissue are not available.

MATERIALS AND METHODS

In 91/105 patients who had been a regular, clinically-indicated surgery (arthroplasty of the hip joint) the respective femoral head (FK) was taken under standardized conditions. Using a checklist defined clinical and radiological criteria of FK are judged in terms of their quality (cysts, necrosis, calcification, deformities, osteoporosis) and divided by the Tabea FK score into three classes (best/middle/poor quality). This was followed by a blinded repeated scoring, now as macroscopic assessment of three sawed layers from the same femoral head. The femoral heads are examined by peripheral quantitative computed tomography (pQCT) and a standardized histological examination of the bony tissue. We evaluated the accordance of the Tabea FK score with complementary assessments by calculation of sensitivity and specificity.

RESULTS

Femoral heads from 91/105 patients (ages: 68.4 ± 9.9 , n = 60 women, n = 31 men) were explanted and included in the study. The correlation between the primary radiologic clinical score (Tabea FK score) and the macroscopic second review of the sawn FK with respect to middle/best and poor/middle quality was classified as good (sensitivity 77% and 81%, respectively; specificity 76% and 84%, respectively). The correlation of histology and macroscopic second review was worse and in relation to discrimination of middle/best and poor/middle quality had a sensitivity of 85% and 54%, respectively, and a specificity of 66% and 97%, respectively. The pQCT showed a sensitivity of 82% only in discrimination of middle/best, while sensitivity in discrimination of poor/middle and poor/middle + best, respectively, was <10%.

DISCUSSION

The corresponding correlation between the primary and the second clinical score was evaluated as good. This emphasizes the long-standing skills of operationally active orthopedic surgeons to classify the quality of cancellous bone correctly already on the basis of X‑ray images and intraoperative findings. In this respect, the introduction of the Tabea FK score as a quality assurance tool in the routines of bone banks can be recommended.

The choice between allograft or demineralized bone matrix is not unambiguous in trauma surgery

In fracture surgery, large bone defects and non-unions often require bone transplantation, and alternatives to autograft bone substitutes in the form of allografts from bone banks and the derivate demineralised bone matrix (DBM) are widely used. With a focus on efficacy, clinical evidence, safety, cost, and patient acceptance, this review evaluated the difference between allogeneic allograft or DBM as a bone substitute in trauma surgery. The efficacy in supporting bone healing from allograft and DBM is highly influenced by donor characteristics and graft processing. Mechanical stability is achieved from a structural graft. Based on the existing literature it is difficult to identify where DBM is useful in trauma surgery, and the level of evidence for the relevant use of allograft bone in trauma is low. The risk of transmitting diseases is negligible, and the lowest risk is from DBM due to the extensive processing procedures. A cost comparison showed that DBM is significantly more expensive. The experiences of dental patients have shown that many patients do not want to receive allografts as a bone substitute. It is not possible to definitively conclude whether it makes a difference if allograft or DBM is used in trauma surgery. It is ultimately the surgeon's individual choice, but this article may be useful in providing considerations before a decision is made.

Role of embryonic origin on osteogenic potential and bone repair capacity of rat calvarial osteoblasts

INTRODUCTION

The aim of this study was to evaluate the in vitro osteogenic potential of osteoblasts from neural crest-derived frontal bone (OB-NC) and mesoderm-derived parietal bone (OB-MS) and the bone formation induced by them when injected into calvarial defects.

MATERIALS AND METHODS

Calvarial bones were collected from newborn Wistar rats (3-day old) and characterized as frontal and parietal prior to OB-NC and OB-MS harvesting. The cells were cultured, and several parameters of osteoblast differentiation were evaluated. These cells, or PBS without cells (control), were locally injected into 5-mm rat calvarial defects (5 × 10⁶ cells/defect) and after 4 weeks bone formation was evaluated by morphometric and histological analyses.

RESULTS

The characterization of frontal and parietal bones assured the different embryonic origin of both cell populations, OB-NC and OB-MS. The OB-NC presented higher proliferation while the OB-MS presented higher alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of runt-related transcription factor 2, Alp, bone sialoprotein and osteocalcin revealing their high osteogenic potential. µCT analysis indicated that there was higher amount of bone formation in defects injected with both OB-NC and OB-MS compared to the control. Moreover, the bone tissue formed by both cells displayed the same histological characteristics.

CONCLUSIONS

Despite the distinct in vitro osteogenic potential, OB-NC and OB-MS induced similar bone repair in a rat calvarial defect model. Thus, osteoblasts, irrespective of their in vitro osteogenic potential linked to embryonic origins, seem to be suitable for cell-based therapies aiming to repair bone defects.

Analysis of the order-implantation relationship for musculoskeletal tissue transplantation

OBJECTIVE

To analyze orders requested from a musculoskeletal tissue bank and to evaluate the percentage of tissue implantation.

MATERIAL AND METHODS

Two hundred and sixty-five orders for musculoskeletal tissue were analyzed over the course of a year.

EXCLUSIONS

5 duplications and 5 orders for which there was no availability to cover the need. We analyzed the number of surgeries in which the graft was finally used.

RESULTS

Of a total of 255 orders, the graft was used in 178 (70%), and the graft was not used in 77 (30%). Of the 178 used, there was a partial refund in 23 (10%). Of the 77 orders not used, surgery was performed in 32 (13%) without the use of bank tissue, while surgery was discontinued in the remaining 45 (17%).

DISCUSSION

A non-utilization rate of 30% was identified, of which 17% was from surgery that was not performed and 13% from surgery that was performed, but the tissue was returned to the tissue bank, because it was not required. In a further 10% there was partial return of the tissue. Based on this analysis, we consider that it is important to have direct confirmation of the surgery to avoid sending tissue for discontinued surgeries, since in addition to the economic impact, the bank must ensure adequate temperature maintenance during transportation and storage in the transplantation centre, to avoid discarding said tissue if it is returned.

Partial Resurfacing for Humeral Head Defects Associated With Recurrent Shoulder Instability

Recurrent traumatic shoulder instability is a complex clinical entity that commonly affects young, active patients. Humeral head defects are frequently associated with this condition, but specific treatment to stabilize the shoulder is rarely needed. Management options for defects of the humeral head that do necessitate treatment carry various risks and disadvantages, including the need for bone or soft tissue healing, complications related to hardware, and loss of motion. Partial prosthetic resurfacing has been reported as a treatment option. The current study retrospectively reviewed a cohort of patients with recurrent or locked anterior and posterior instability who underwent partial prosthetic humeral head resurfacing for significant Hill-Sachs and reverse Hill-Sachs lesions. At an average of 36.4 months after the index procedure, 16 patients were contacted by mail and telephone. Of the study group, 13 patients underwent partial resurfacing for anterior instability and 3 patients underwent partial re-surfacing for posterior instability. No patient had a repeat dislocation. In addition, 77% of patients in the anterior instability cohort and all of the patients in the posterior instability cohort returned to their full preinjury activity level. For the anterior instability cohort, significant improvements from preoperatively to final follow-up occurred for mean Musculoskeletal Review of System score (4.54, P<.0001) and Short Form-12 physical component score (9.52, P=.002). For the combined cohort, the Penn Shoulder Score improved by 36.4 points (P=.059). This study showed the effectiveness of partial humeral head resurfacing for preventing redislocation for patients with significant Hill-Sachs and reverse Hill-Sachs lesions. [Orthopedics. 2017; 40(6):e996-e1003.].

Intraoperative culture positive allograft bone and subsequent postoperative infections: a retrospective review

BACKGROUND

Obtaining intraoperative cultures of allograft bone just before use in orthopedic procedures is standard practice in many centres; however, the association between positive cultures and subsequent surgical infections is unknown. Our study had 3 goals: to determine the prevalence of positive intraoperative allograft culture and subsequent infection; to determine if, in cases of subsequent infection, organisms isolated at reoperation were the same as those cultured from the allograft at the time of the index procedure; and to assess the costs associated with performing intraoperative allograft cultures.

METHODS

In this retrospective case series, we obtained data on patients receiving allograft bone between 2009 and 2012. Patients receiving allograft with positive cultures were reviewed to identify cases of significant infection. Organisms isolated at reoperation were compared with the allograft culture taken at the time of implantation, and we performed a cost assessment.

RESULTS

Of the 996 allograft bone grafts used, 43 (4.3%) had positive intraoperative cultures and significant postoperative infections developed in 2, requiring reoperation. Antibiotics based on culture results were prescribed in 24% of cases. Organisms cultured at the time of reoperation differed from those isolated initially. The cost of performing 996 allograft cultures was $169 320.

CONCLUSION

This series suggests that rates of positive intraoperative bone allograft culture are low, and subsequent infection is rare. In cases of postoperative infection, primary allograft culture and secondary tissue cultures isolated different organisms. Costs associated with performing cultures are high. Eliminating initial culture testing could save $42 500 per year in our health region.

Treatment of critically sized femoral defects with recombinant BMP-2 delivered by a modified mPEG-PLGA biodegradable thermosensitive hydrogel

Background

Reconstruction of a segmental fracture with massive bone loss is still a challenge for orthopaedic surgeons. The aim of our study was to develop a suitable biodegradable thermosensitive hydrogel system as a carrier for bone morphogenetic protein (BMP)-2 delivery in the treatment of critical-sized femoral defects.

Methods

A block copolymer composed of monomethoxypoly(ethylene glycol) (mPEG), poly(lactic-co-glycolic acid) (PLGA) and 2, 2’-Bis (2-oxazolin) (Box) was synthesized by ring opening polymerization. The synthesized block copolymer was characterized by ¹H-NMR spectroscopy and gel permeation chromatography (GPC). Different biophysical and biochemical properties of the synthesized copolymer, including temperature-induced structure changes, degradation rate, pH changes during hydrolytic degradation, cell toxicity, and the release profile of BMP-2, were also evaluated and/or were compared with those of a well-characterized mPEG-PLGA copolymer. In animal testing, rabbits (n = 36) that received critically sized (10 mm) femoral defects were divided into 6 groups. These experimental groups included an untreated group, autograft, and groups treated with the synthesized copolymer carrying different concentrations of BMP-2 (0, 5, 10, and 20 μg/ml). Bone repair was evaluated using X-ray radiography, histological staining, micro-computed tomography (μCT), biomarker examination and biomechanical testing in a 12-week treatment period.

Results

A new thermosensitive mPEG-PLGA/Box/mPEG-PLGA block copolymer, or named as BOX copolymer, was successfully prepared. Compared to the reported mPEG-PLGA in vitro, the prepared BOX copolymer at the same weight percent concentrations exhibited wider temperature ranges of gelation, slower degradation rates, higher the pH values, as well as less cytotoxicity. Furthermore, the BMP-2 release from BOX hydrogel exhibited a near-linear release profile in vitro. In animal experiments, treatment of critical-sized bony defects with 25 wt% BOX hydrogel carrying BMP-2 effectively promoted fracture healing during the 12-week trial period and higher concentrations of BMP-2 treatment correlated with better bone quality. Most importantly, clinical outcome and bone healing in the BOX-hydrogel group with 20 μg/ml BMP-2 were nearly equivalent to those in the autograft group in a 12-week treatment course.

Conclusion

These data support that the use of BOX hydrogel (25 wt%) as a drug delivery system is a promising method in the treatment of large bone defects.

An audit of consent for allograft use in elective orthopaedic surgery

Introduction Patients receiving musculoskeletal allografts may be at risk of postoperative infection. The General Medical Council guidelines on consent highlight the importance of providing patients with the information they want or need on any proposed investigation or treatment, including any potential adverse outcomes. With the increased cost of defending medicolegal claims, it is paramount that adequate, clear informed patient consent be documented. Methods We retrospectively examined the patterns of informed consent for allograft bone use during elective orthopaedic procedures in a large unit with an onsite bone bank. The initial audit included patients operated over the course of 1 year. Following a feedback session, a re-audit was performed to identify improvements in practice. Results The case mix of both studies was very similar. Revision hip arthroplasty surgery constituted the major subgroup requiring allograft (48%), followed by foot and ankle surgery (16.3%) and revision knee arthroplasty surgery (11.4%) .On the initial audit, 17/45 cases (38%) had either adequate preoperative documentation of the outpatient discussion or an appropriately completed consent form on the planned use of allograft. On the re-audit, 44/78 cases (56%) had adequate pre-operative documentation. There was little correlation between how frequently a surgeon used allograft and the adequacy of consent (Correlation coefficient -0.12). Conclusions Although the risk of disease transmission with allograft may be variable, informed consent for allograft should be a routine part of preoperative discussions in elective orthopaedic surgery. Regular audit and feedback sessions may further improve consent documentation, alongside the targeting of high volume/low compliance surgeons.

Post-operative infection with fresh frozen allograft: reported outcomes of a hospital-based bone bank over 14 years

Femoral head bone allografts have traditionally been used to provide mechanical stability to areas of bony deficiency, or for its osteoinductive and osteoconductive properties. Concerns have been raised over increased infection rates following the use of fresh-frozen graft tissue. This retrospective study aims to investigate the outcomes of fresh frozen femoral heads kept in a regulated, non-commercial bone bank at a university teaching hospital.The local bone bank database was used to identify released femoral heads during a 14 year study period (September 1999-December 2013) whereby a retrospective review of patient records was undertaken to determine clinical outcome. During the observed study period, 427 femoral heads were released from cold storage. Of these, 270 femoral heads had a mean follow-up of 347 days. 157 femoral heads were excluded due to insufficient follow-up data (n = 132) or discarded due to breaks in the cold chain prior to use (n = 25). Of the 270 included femoral heads, 231 (85.6 %) had no reported complications with good graft incorporation. In the remaining 39 with reported complications, only 5 (2.6 %) developed a postoperative infection. Our findings suggest that the use of fresh frozen allograft does not materially increase the risk of post-operative bacterial infection. Our reported post-operative infection rates are comparable with infection rates of other similar studies on fresh frozen allograft use.

A positive bacterial culture from allograft bone at implantation does not correlate with subsequent surgical site infection

Fresh-frozen allograft bone is frequently used in orthopaedic surgery. We investigated the incidence of allograft-related infection and analysed the outcomes of recipients of bacterial culture-positive allografts from our single-institute bone bank during bone transplantation. The fresh-frozen allografts were harvested in a strict sterile environment during total joint arthroplasty surgery and immediately stored in a freezer at -78º to -68º C after packing. Between January 2007 and December 2012, 2024 patients received 2083 allografts with a minimum of 12 months of follow-up. The overall allograft-associated infection rate was 1.2% (24/2024). Swab cultures of 2083 allografts taken before implantation revealed 21 (1.0%) positive findings. The 21 recipients were given various antibiotics at the individual orthopaedic surgeon’s discretion. At the latest follow-up, none of these 21 recipients displayed clinical signs of infection following treatment. Based on these findings, we conclude that an incidental positive culture finding for allografts does not correlate with subsequent surgical site infection. Additional prolonged post-operative antibiotic therapy may not be necessary for recipients of fresh-frozen bone allograft with positive culture findings.

Cite this article: Bone Joint J 2015;97-B:427–31.

Staphylococcal biofilm formation on the surface of three different calcium phosphate bone grafts: a qualitative and quantitative in vivo analysis

Differences in physico-chemical characteristics of bone grafts to fill bone defects have been demonstrated to influence in vitro bacterial biofilm formation. Aim of the study was to investigate in vivo staphylococcal biofilm formation on different calcium phosphate bone substitutes. A foreign-body guinea-pig infection model was used. Teflon cages prefilled with β-tricalcium phosphate, calcium-deficient hydroxyapatite, or dicalcium phosphate (DCP) scaffold were implanted subcutaneously. Scaffolds were infected with 2 × 10(3) colony-forming unit of Staphylococcus aureus (two strains) or S. epidermidis and explanted after 3, 24 or 72 h of biofilm formation. Quantitative and qualitative biofilm analysis was performed by sonication followed by viable counts, and microcalorimetry, respectively. Independently of the material, S. aureus formed increasing amounts of biofilm on the surface of all scaffolds over time as determined by both methods. For S. epidermidis, the biofilm amount decreased over time, and no biofilm was detected by microcalorimetry on the DCP scaffolds after 72 h of infection. However, when using a higher S. epidermidis inoculum, increasing amounts of biofilm were formed on all scaffolds as determined by microcalorimetry. No significant variation in staphylococcal in vivo biofilm formation was observed between the different materials tested. This study highlights the importance of in vivo studies, in addition to in vitro studies, when investigating biofilm formation of bone grafts.

Simple signaling molecules for inductive bone regenerative engineering

With greater than 500,000 orthopaedic procedures performed in the United States each year requiring a bone graft, the development of novel graft materials is necessary. We report that some porous polymer/ceramic composite scaffolds possess intrinsic osteoinductivity as shown through their capacity to induce in vivo host osteoid mineralization and in vitro stem cell osteogenesis making them attractive synthetic bone graft substitutes. It was discovered that certain low crystallinity ceramics partially dissociate into simple signaling molecules (i.e., calcium and phosphate ions) that induce stem cells to endogenously produce their own osteoinductive proteins. Review of the literature has uncovered a variety of simple signaling molecules (i.e., gases, ions, and redox reagents) capable of inducing other desirable stem cell differentiation through endogenous growth factor production. Inductive simple signaling molecules, which we have termed inducerons, represent a paradigm shift in the field of regenerative engineering where they can be utilized in place of recombinant protein growth factors.

Prevalence of microbiological markers in bone tissue from live and cadaver donors in the musculoskeletal tissue bank of Passo Fundo

Objective

To conduct an epidemiological analysis on the main microbiological markers in bone tissue that was processed at the musculoskeletal tissue bank of Hospital São Vicente de Paulo, in Passo Fundo, between August 2007 and October 2011.

Methods

Between August 2007 and October 2011, 202 musculoskeletal tissue samples were collected for the tissue bank. Among these, 159 samples were from living donor patients and 43 were from cadaver donors. The following serological tests were requested: hepatitis B, hepatitis C, syphilis, cytomegalovirus, Chagas disease, toxoplasmosis, HIV and HTLV.

Results

Among the 159 living donors, 103 (64.75%) were men and 56 (35.25%) were women. The patients’ mean age was 59.35 ± 8.87 years. Out of this total, 76 tissue samples (47.8%) from donors were rejected. There was no difference in the number of rejections in relation to sex (p = 0.135) or age (p = 0.523). The main cause of rejection was serologically positive findings for the hepatitis B virus, which was responsible for 48 rejections (63.15%). Among the 43 cadaver donors, the mean age was 37.84 ± 10.32 years. Of these, 27 (62.8%) were men and 16 (37.2%) were women. Six of the samples collected from cadaver donors were rejected (13.9%), and the main cause of rejection was serologically positive findings for the hepatitis C virus, which was responsible for three cases (50%). There was no significant difference in the number of rejections in relation to sex (p = 0.21) or age (p = 0.252).

Conclusion

There were a greater number of rejections of tissues from living donors (47.8%) than from cadaver donors (13.9%). Among the living donors, the main cause of rejection was the presence of serologically positive findings of the hepatitis B virus, while among the cadaver donors, it was due to the hepatitis C virus.

Comparison of four different allogeneic bone grafts for alveolar ridge reconstruction: a preliminary histologic and biochemical analysis

OBJECTIVES

Allograft material for alveolar ridge reconstruction is quite promising and appears to be as equally successful as bone autograft material. The aim of the present study was to compare four different allogeneic bone grafts in terms of their histologic structure and DNA content before grafting.

STUDY DESIGN

Four allograft specimens from different suppliers were analyzed histologically, and the DNA content was analyzed before clinical use of the allografts.

RESULTS

Organic tissue remnants were detected in all of the evaluated samples. In the present samples adipocytes, fibroblasts, osteocytes, and chondrocytes were identified and DNA isolation and purification was possible.

CONCLUSION

Demineralized freeze-dried allogeneic bone transplants can stimulate new bone formation and are a viable alternative to bone autograft material. However, the well-tolerated use of allograft material in regard to our findings should be further investigated.

Recommendations and considerations for the use of biologics in orthopedic surgery

Reconstruction of extensive bone defects remains technically challenging and has considerable medical and financial impact on our society. Surgical procedures often require a bone/substitute graft to enhance and accelerate bone repair. Bone autografts are associated with morbidity related to bone harvesting and are limited in quantity. Alternatively, bone allografts expose the patient to the risk of transmission of infectious disease. Synthetic bone graft substitutes, such as calcium sulfates, hydroxyapatite, tricalcium phosphate, and combinations, circumvent some of the disadvantages of auto- and allografts, but have limited indications. Biomedical research has made possible the stimulation of the body's own healing mechanisms, either by delivering exogenous growth factors locally, or by stimulating their local production by gene transfer. Among all known factors having osteoinductive properties, only two bone morphogenetic proteins (for specific indications) and demineralized bone matrix have been approved for clinical use. In addition, ongoing research is exploring the efficacy of cell therapy and tissue engineering. The present report examines the composition, biological properties, indications, clinical experience and regulations of several of the biotherapeutics employed for bone reconstruction.

Bone graft substitutes: What are the options?

Currently, a number of bone grafting materials are available in the clinical setting to enhance bone regeneration, varying from autologous bone to several bone graft substitutes. Although autologous bone remains the "gold standard" for stimulating bone repair and regeneration, the morbidity from its harvesting and its restricted availability generated the need for the development of other materials or strategies either to substitute autologous bone graft or expand its limited supply. Bone graft substitutes can possess one or more components: an osteoconductive matrix, acting as a scaffold; osteoinductive proteins and other growth factors to induce differentiation and proliferation of bone-forming cells; and osteogenic cells for bone formation. Based on their distinct properties, all these bone grafting alternatives have specific indications, and can be used either alone or in combination. In this review, we summarise the available bone grafting materials, focussing mainly on the various bone substitutes and their characteristics, in an effort to specify the indications for their use.

Fungal culture of musculoskeletal tissue: what's the point?

There have not been any studies that review the prevalence of fungal isolates using selective media from samples of banked musculoskeletal tissue retrieved from living and cadaveric donors. A total of 2,036 swab and 2,621 biopsy samples of musculoskeletal tissue from tissue banks were received from the 1st August 2008 till 31st December 2010. Routine culture for fungi using selective media with a prolonged incubation period failed to demonstrate a greater prevalence of fungal isolates than by using non-selective culture media alone. Using selective culture fungi were recovered from only two Sabouraud agar plates (0.1%) but not from non-selective media. During the same period fungi were isolated from three graft samples cultured in non-selective broth media only (0.1%). There was no correlation of fungal isolates from selective or non-selective media inoculated at the same time nor from multiple graft samples collected from the same donor supporting the possibility of an exogenous source for fungal isolates rather than an endogenous source.

Skeletal tissue regeneration: current approaches, challenges, and novel reconstructive strategies for an aging population

Loss of skeletal tissue as a consequence of trauma, injury, or disease is a significant cause of morbidity with often wide-ranging socioeconomic impacts. Current approaches to replace or restore significant quantities of lost bone come with substantial limitations and inherent disadvantages that may in themselves cause further disability. In addition, the spontaneous repair capacity of articular cartilage is limited; thus, investigation into new cartilage replacement and regeneration techniques are warranted. Along with the challenges of an increasingly aging demographic, changing clinical scenarios and rising functional expectations provide the imperative for new, more reliable skeletal regeneration strategies. The science of tissue engineering has expanded dramatically in recent years, notably in orthopedic applications, and it is clear that new approaches for de novo skeletal tissue formation offer exciting opportunities to improve the quality of life for many, particularly in the face of increasing patient expectations. However, significant scientific, financial, industrial, and regulatory challenges should be overcome before the successful development of an emergent tissue engineering strategy can be realized. We outline current practice for replacement of lost skeletal tissue and the innovative approaches in tissue regeneration that have so far been translated to clinical use, along with a discussion of the significant hurdles that are presented in the process of translating research strategies to the clinic.

Novel approaches to bone grafting: porosity, bone morphogenetic proteins, stem cells, and the periosteum

The disadvantages involving the use of a patient's own bone as graft material have led surgeons to search for alternative materials. In this review, several characteristics of a successful bone graft material are discussed. In addition, novel synthetic materials and natural bone graft materials are being considered. Various factors can determine the success of a bone graft substitute. For example, design considerations such as porosity, pore shape, and interconnection play significant roles in determining graft performance. The effective delivery of bone morphogenetic proteins and the ability to restore vascularization also play significant roles in determining the success of a bone graft material. Among current approaches, shorter bone morphogenetic protein sequences, more efficient delivery methods, and periosteal graft supplements have shown significant promise for use in autograft substitutes or autograft extenders.