Successful reconstruction of bone defects requires an adequate filling material that supports regeneration and formation of new bone within the treated defect in an optimal fashion. Currently available synthetic bone graft substitutes cannot fulfill all requirements of the highly complex biological processes involved in physiological bone healing. Due their unphysiologically asynchronous biodegradation properties, their specific foreign material-mediated side effects and complications and their relatively modest overall osteogenic potential, their overall clinical performance typically lags behind conventional bone grafts of human origin. However, defect- and pathology specific combination of synthetic bone graft substitutes exhibiting appropriate carrier properties with therapeutic agents and/or conventional bone graft materials allows creation of biologically enhanced composite constructs that can surpass the biological and therapeutic limits even of autologous bone grafts. This presentation introduces a bone defect reconstruction concept based on biological enhancement of optimal therapeutic agent-carrier composites and provides a rationale for an individual, requirement-specific adaptation of a truly patient-specific reconstruction of bone defects. It represents the pinnacle of the bone defect reconstruction pyramid, founded on the basic principles and prerequisites of complete elimination of the underlying pathology, preservation, augmentation or restoration of mechanical stability of the treated bone segment and creation of a biodegradable scaffold with adequate mechanical integrity. It summarises the current body of relevant experimental and clinical research, presents clinical case examples illustrating the various aspects of the proposed concept as well as early clinical results. The author hopes that the theoretical and conceptual framework provided, will help guide future research as well as clinical decision making with respect to this particular field.
In certain clinical situations, complex local anatomy and limitations of surgical exposure can make adequate and bone tumor ablation, resection and reconstruction very challenging. We wished to review our clinical experience and accuracy achieved with entirely virtually planned single stage tumor ablation/resection and reconstructions. We report 6 cases of bone tumors in which tumor removal (by radio-frequency (RF) ablation and/or resection) and subsequent reconstruction were based entirely on pre-operative virtual analysis and planning. All interventions were accomplished with specifically designed and pre-operatively manufactured 3D-printed drill & resection guides. Immediate subsequent defect reconstruction was either performed with a precisely matching allograft (n=1) or composite metal implant (n=5) consisting of a defect specific titanium scaffold and multiple integrated fixation features to provide optimal immediate stability as well as subsequent opportunity for osseointegration. We reviewed the sequence of all procedural steps as well as the accuracy of each saw blade or drill trajectory by direct intra-operative measurement, post-operative margin status and virtual comparison of pre- and post-operative CT scans.Background
Methods
A gentamicin-eluting biocomposite consisting of hydroxyapatite (HA) and calcium sulphate (CaS)*1 can provide effective dead space management and bone formation in chronic osteomyelitis. However, radiographic follow-up after implantation of this biomaterial has shown imaging features previously not described with other comparable bone graft substitutes. Last year we presented preliminary results with a follow-up of 6 months. Now we present the radiographic, µCT and histological one-year follow-up of the critical-size bone defect model in sheep. The aim of this study was to simulate the clinical situation in a large animal model to correlate different imaging techniques used in the clinic (Radiography, CT and MRI scans) with histological finding. Standardised bone defects were created in ten Merino-wool sheep (age two to four years). Large drill holes (diameter 2.5cm, depth 2cm, volume approx. 10ml) were placed in the medial femoral condyles of both hind legs and filled with gentamicin-eluting biocomposite. Initially surgery was carried out on the right hind leg. Three months later, an identical intervention was performed on the contralateral side. Animals were sacrificed at three and six weeks and 4.5, six and twelve months. Radiographs and MRI scans were taken immediately after sacrifice. Filled bone voids were harvested en-block and analysed using µCT, and histology.Aim
Methods
As tumours of bone and soft tissue are rare, multicentre prospective collaboration is essential for meaningful research and evidence-based advances in patient care. The aim of this study was to identify barriers and facilitators encountered in large-scale collaborative research by orthopaedic oncological surgeons involved or interested in prospective multicentre collaboration. All surgeons who were involved, or had expressed an interest, in the ongoing Prophylactic Antibiotic Regimens in Tumour Surgery (PARITY) trial were invited to participate in a focus group to discuss their experiences with collaborative research in this area. The discussion was digitally recorded, transcribed and anonymised. The transcript was analysed qualitatively, using an analytic approach which aims to organise the data in the language of the participants with little theoretical interpretation.Objectives
Methods
A gentamicin-eluting biocomposite consisting of hydroxyapatite and calcium sulfate1 can provide effective dead space management in chronic osteomyelitis. However, radiographic follow-up after implantation of this novel material has consistently shown evidence of several unique imaging features previously not described with other comparable bone graft substitutes. Conclusive interpretation of these newly described imaging features is difficult as long term follow-up and histological correlation is not yet available. The aim of this study was to establish a large animal model, closely simulating the clinical situation in order to permit further analysis of imaging features in correlation with histological progression of bone remodelling. Standardised bone defects were created in ten Merino-wool sheep (age: two to four years). Large drill holes (diameter 2.5cm, depth 2cm, volume approx. 10ml) were placed in the medial femoral condyles of both hind legs and filled with a gentamicin antibiotic eluting bone graft substituteAim
Method
The demand for a synthetic bone substitute that can build bone and at the same time kill bacteria is high. The aim of this study was to compare the elution of gentamicin from a new synthetic bone substitute Gentamicin release was measured from a synthetic bone graft substitute, comparing elution in Ringers solution. The bone graft substitute contained 175mg gentamicin per 10mL. The material was introduced either as paste or as pre-set beads with a high or low surface areas, >100cm2 and 24cm2 respectively. The gentamycin release was measured by daily collection of samples. elution in patients treated for trochanteric hip fractures(n=6) or uncemented hip revisions(n=5) 7,3±1,1mL of substitute was implanted and drainage was collected at 6h,12h,24h,30h,36h post-op. Blood serum was collected every hour for the first 6h and thereafter every 6h until 4 days post-op, urine – daily for the first 7 days post-op. elution in patients treated after bone tumor resection(n=8), 12,1±5,5mL of substitute was implanted and both drainage and blood serum were collected daily until 2 days post-op. Gentamicin concentrations were analyzed using antibody technique.Aim
Method
We have observed clinical cases where bone is formed in the overlaying muscle covering surgically created bone defects treated with a hydroxyapatite/calcium sulphate biomaterial. Our objective was to investigate the osteoinductive potential of the biomaterial and to determine if growth factors secreted from local bone cells induce osteoblastic differentiation of muscle cells. We seeded mouse skeletal muscle cells C2C12 on the hydroxyapatite/calcium sulphate biomaterial and the phenotype of the cells was analysed. To mimic surgical conditions with leakage of extra cellular matrix (ECM) proteins and growth factors, we cultured rat bone cells ROS 17/2.8 in a bioreactor and harvested the secreted proteins. The secretome was added to rat muscle cells L6. The phenotype of the muscle cells after treatment with the media was assessed using immunostaining and light microscopy.Objectives
Materials and Methods
Deep bone and joint infections (DBJI) are directly intertwined with health, demographic change towards an elderly population, and wellbeing. The elderly human population is more prone to acquire infections, and the consequences such as pain, reduced quality of life, morbidity, absence from work and premature retirement due to disability place significant burdens on already strained healthcare systems and societal budgets. DBJIs are less responsive to systemic antibiotics because of poor vascular perfusion in necrotic bone, large bone defects and persistent biofilm-based infection. Emerging bacterial resistance poses a major threat and new innovative treatment modalities are urgently needed to curb its current trajectory. We present a new biphasic ceramic bone substitute consisting of hydroxyapatite and calcium sulphate for local antibiotic delivery in combination with bone regeneration. Gentamicin release was measured in four setups: 1) Objectives
Materials and Methods
To demonstrate the role of an antibiotic containing bone substitute, native bone active proteins and muscle transforming into bone.
Recurrent osteomyelitis was eradicated and filled with a gentamycin eluting bone substitute (Cerament™l G) consisting of sulphate and apatite phases and covered by a muscle flap. C2C12 muscle cells were seeded on the bone substitute in-vitro and their phenotype was studied. Another muscle cell line L6 was seeded with osteoblast conditioned medium containing bone active proteins and specific markers were studied for bone differentiation.
A chronic, longstanding, fistulating osteomyelitis was operated with radical eradication and filling of the cavity with gentamycin eluting bone substitute. At one year, the patient had no leg pain and a healed wound. Significant bone was also seen in the overlaying muscle, at one month post-op disappearing after 6-months. Local delivery of gentamycin had a protective effect on bone formation. C2C12 cells seeded on the gentamycin eluting bone substitute depicted no difference in proliferation when compared to plain bone substitute and expressed 4 folds higher Alkaline phosphatase (ALP) compared to controls. C2C12 cells expressed proteins and genes coding for collagen type 1 (Col 1), osteocalcin (OCN), osteopontin (OPN) and bonesialoprotein (BSP). L6 cells cultured with osteoblast conditioned medium remained uninucleated and expressed osteoblastic proteins like Col 1, OCN, OPN and BSP.
Bone substitute with gentamycin leads to differentiation of mesenchymal cells into bone in-vitro. Native bone active proteins from an osteoblast culture can induce differentiation of muscle cells in-vitro. Clinical observations with rapid bone formed in the bone substitute and in some cases in the muscle are a consequence of both leakage of bone active proteins and also from osteoprogenitor cells coming from the overlaying muscle interacting with the osteoinductive bone substitute.
To report our experience with the use of local antibiotic co-delivery with a synthetic bone graft substitute during a second stage re-implantation of an infected proximal humeral replacement. A 72 year old man was admitted to our department with a pathological fracture through an osteolytic lesion in the left proximal humerus, due to IgG Myelomatosis. He was initially treated with a cemented proximal humerus replacement hemiarthroplasty. Peri-prosthetic joint infection (PJI) with significant joint distention was evident three weeks post operatively. Revision surgery confirmed presence of a large collection of pus and revealed disruption of the soft tissue reattachment tube, as well as complete retraction of rotator cuff and residual capsule. All modular components were removed and an antibiotic-laden cement spacer (1.8g of Clindamycin and Gentamycin, respectively) was implanted onto the well-fixed cemented humeral stem. Initial treatment with i.v. Amoxicillin/Clavulanic acid was changed to Rifampicin and Fusidic Acid during a further 8 weeks after cultures revealed growth of S. epidermidis. During second stage revision, a hybrid inverse prosthesis with silver coating was implanted, with a total of 20 ml Cerament ™G (injected into the glenoid cavity prior to insertion of the base plate and around the humeral implant-bone interface) and again stabilized with a Trevira tube. Unfortunately, this prosthesis remained unstable, ultimately requiring re-revision to a completely new constrained reverse prosthesis with a custom glenoid shell and silver-coated proximal humeral component. 18 months postoperatively, the patient's shoulder remains pain free and stable, without signs of persistent or reinfection since the initial second stage revision. The function however, unfortunately remains poor. This case report illustrates the application of an antibiotic-eluting bone graft substitute in a specific clinical situation, where co-delivery of an antibiotic together with a bone remodeling agent may be beneficial to simultaneously address PJI as well as poor residual bone quality.
To document early in-vivo concentrations of gentamicin in plasma and drain fluid after bone defect reconstruction using a gentamicin-eluting bone graft substitute. Introduction Reconstruction of bone defects after surgical bone tumor resection is associated with an increased risk of infection and some surgeons therefore prefer extended antibiotic prophylaxis in these patients. A gentamicin-eluting bone graft substitute consisting of sulphate and apatite has been shown to be effective for treatment of osteomyelitis(1) and may be a valuable addition to the therapeutic and/or prophylactic antibiotic regime for this and many other indications. We performed a prospective pilot study from December 2014 to February 2015 in 7 patients (M/F: 4/3, mean age 51 (37–79) years) who underwent bone defect reconstruction with a gentamicin-eluting bone graft substitute (CERAMENT™|G – BONESUPPORT AB) containing 175 mg gentamicin per 10 mL. Indications for surgery were metastatic bone disease (n=3, proximal humerus), giant cell tumor (n=2, distal femur), aseptic prosthetic loosening (n=1, knee) and chondroid tumor (n=1, distal femur). Additional endoprosthetic reconstruction with a tumor prosthesis was performed in 3 patients (2 proximal humerus and 1 distal femur). Drain fluid and plasma was collected immediately postoperatively and each postoperative day until the drain was removed. In 2 cases we were unable to collect drain fluid directly postoperatively due to minimal fluid production. Gentamicin concentrations were analyzed using an antibody technique (Indiko™ – Thermo Scientific). A mean of 14 (10–20) mL gentamicin-eluting bone graft substitute was used, either alone or in combination with cancellous allograft and/or a bone graft substitute not containing gentamicin (CERAMENT™|BVF – BONESUPPORT AB). Mean drain fluid concentrations of gentamicin were 1200 (723–2100) mg/L immediately postoperative (0–2 hours), 1054 (300–1999) mg/L on day 1 (17–23 hours) and 509 (38–1000) mg/L on day 2 (39–45 hours). Mean plasma concentrations of gentamicin were 1.26 (1.08–1.42) mg/L immediately postoperative, 0.95 (0.25–2.06) mg/L on day 1 and 0.56 (0.20–0.88) mg/L on day 2. Discussion. As gentamicin induces a concentration-dependent bacterial killing effect, the obviously high local peak concentrations of gentamicin found in this study would be expected to deliver a substantial prophylactic effect after long operations with an increased risk of intraoperative bacterial contamination. Local implantation of a gentamicin-eluting bone graft substitute for bone defect reconstruction results in high concentrations of gentamicin in the drain fluid in the first postoperative days and low plasma concentrations.
Endoprosthetic reconstruction for pathologic acetabular fractures is associated with a high risk of periprosthetic joint infection. In this setting, bone defect reconstruction utilising co-delivery of a synthetic bone substitute with an antibiotic, is an attractive treatment option from both, therapeutic and prophylactic perspective. We wished to address some concerns that remain regarding the possible presence of potentially wear inducing particles in the periprosthetic joint space subsequent to this procedure. We analysed a drain fluid sample from an endoprosthetic reconstruction of a pathologic acetabular fracture with implantation of a gentamicin eluting, biphasic bone graft substitute, consisting of 40% hydroxyapatite (HA) and 60% calcium sulphate (CERAMENT G), into the residual peri-acetabular bone defect. This sample was divided into two 1.5ml subsamples, to one of which 100mg HA particles were added as control before burning off all organic substance at very high temperature. These heat treated samples were then examined with scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDAX) and compared to a reference sample consisting of HA particles only. On SEM, hydroxyapatite particles were readily recognisable in the control and reference samples, whereas only very few particles over 2μm were apparent in the ”pure” drain sample. EDAX revealed that very large amounts of salts were present in both drainage samples. The pure drainage sample however, contained markedly lower amounts of calcium and phosphate compared to reference and control samples. No HA particles as such, were seen in the pure sample, however their presence cannot be excluded with absolute certainty, as some particles might have been hidden within the large salt conglomerates. We could not find clear evidence that the drain fluid really contained HA particles. More thorough investigations are needed and future analyses with prior removal of the high salt content would likely yield more conclusive results.
