Invasive intraneural electrodes implanted in peripheral nerves are neural prosthetic devices that are exploied to control advanced neural-interfaced prostheses in human amputees. One of the main issues to be faced in chronic implants is represented by the gradual loss of functionality of such intraneural interfaces due to an electrical impedance increase caused by the progressive formation of a fibrotic capsule around the electrodes, which is originally due to a nonspecific inflammatory response called foreign body reaction (FBR). In this in vitro work, we tested the biocompatibility and ultra-low fouling features of the synthetic coating - poly(ethylene glycol) (PEG) - compared to the organic polymer - zwitterionic sulfated poly(sulfobetaine methacrylate) (SBMA) hydrogel - to prevent or reduce the first steps of the FBR: plasma protein adsorption and cell adhesion to the interface. Synthesis and characterization of the SBMA hydrogel was done. Preliminary biocompatibility analysis of the zwitterionic hydrogel, using hydrogel-conditioned medium, showed no cytotoxicity at all vs. control. We seeded GFP-labelled human myofibroblasts on PEG- and SBMA hydrogel-coated polyimide surfaces and evaluated their adhesion and cell viability at different time-points. Because of the high hydration, low stiffness reflecting the one of neural tissue, and ultra-low fouling characteristics of the SBMA hydrogel, this polymer showed lower myofibroblast adhesion and different cell morphology compared to adhesion controls, thereby representing a better coating than PEG for potentially mitigating the FBR. We conclude that soft SBMA hydrogels could outperform PEG coatings in vitro as more suitable dressings of intraneural electrodes. Furthermore, such SBMA-based antifouling materials can be envisioned as long-term diffusion-based delivery systems for controlled release of anti-inflammatory and anti-fibrotic drugs in vivo

Aim of the study: The aim of this study was to explore whether adverse reactions would occur during the material’s degradation period even at a later time point after fracture healing had been completed, in metacarpal fractures treated with third generation bioabsorbable implants. Materials and Methods: 12 unstable, displaced metacarpal fractures in 10 consecutive patients (7 males, 3 females; mean age 36.4 y, range 18–75 y) were treated with third generation absorbable plates and screws (Inion. ®. OTPSTM Biodegradable Mini Plating System), where resorption is supposed to occur within 2 to 4 years. 9 patients (10 fractures) were available for follow-up (mean 25.6 months, range 14 to 44 m) and were examined both clinically and radiologically. For patients without appearance of foreign body reaction the minimum follow-up time was 24 months. Results: Fracture healing was uneventful in all cases. A foreign body reaction was observed more than a year postoperatively in 4 patients, who were subjected to surgical debridement and implant remnants removal. Histological examination confirmed the diagnosis of aseptic inflammation and foreign body reaction. 2 further patients reported a self subsiding transient local swelling. Conclusion: Our results indicate that modern absorbable implants with longer degradation period have not eliminated the problem of foreign body reaction, but simply postponed it at a later time postoperatively. Patients treated with bioabsorbable implants should be advised of this possible late complication and should be followed for at least two years, possibly longer

The aim of this study was to explore whether adverse reactions would occur during the material’s degradation period even at a later time point after surgery and whether these phenomena were clinically significant and would influence the final outcome. 12 unstable, displaced metacarpal fractures in 10 patients (7 males, 3 females; mean age 36.4 y, range 18–75 y) were treated with the Inion. ®. OTPSTM Biodegradable Mini Plating System. 9 patients (10 fractures) were available for follow-up (mean 25.6 months, range 14 to 44 m). For patients without appearance of foreign body reaction the minimum follow-up time was 24 months. Patients were examined both radiologically to evaluate fracture healing, and clinically by completing the DASH-score and a visual analogue scale for pain assessment. Grip strength, finger strength and range of motion of metacarpo-phalangeal and interphalangeal joints were measured. Fracture healing occurred uneventfully in all patients within six weeks. The most important complication was a foreign body reaction observed in 4 of our patients more than a year postoperatively. All were re-operated and had the materials removed. Histological examination confirmed the diagnosis of aseptic inflammation and foreign body reaction. Although internal fixation of metacarpal fractures by using bioabsorbable implants is a satisfactory alternative fixation method, patients should be advised of this possible late complication and should be followed postoperatively for at least one and a half year, possibly longer

A patient in his thirties developed synovitis with grade 4 chondrolysis and a stiff knee with a fixed flexion deformity between three and six years following PLC and PCL reconstruction using LARS (Ligament Augmentation and Reconstruction System, Corin). There was histologic evidence of foreign body reaction, the knee was painful, swollen and stiff. We did not use any further LARS ligaments for soft tissue reconstructions of the kneein our practice. We commenced a recall programme for all 83 patients patients who underwent a soft tissue knee reconstruction using LARS. Of those contacted, 41 replied (49%) and 16 patients had symptoms (19%) and were investigated further with XRay, MRI and arthroscopy as indicated. We discovered a total of five patients had histologically proven synovitis with foreign body reactions (6%), three of whom had life-changing symptomatic pain, swelling and stiffness with degenerate changes (3.6%). These patients had undergone various reconstructions, including a) PLC only, b) ACL and PCL, c) PCL and PLC and d) ACL, PCL and PLC. A further single case of massive bone cyst formation was noted, following PCL reconstruction using LARS (1.2%)

Intraneural electrodes can be harnessed to control neural prosthetic devices in human amputees. However, in chronic implants we witness a gradual loss of device functionality and electrode isolation due to a nonspecific inflammatory response to the implanted material, called foreign body reaction (FBR). FBR may eventually lead to a fibrous encapsulation of the electrode surface. Poly(ethylene glycol) (PEG) is one of the most common low-fouling materials used to coat and protect electrode surfaces. Yet, PEG can easily undergo encapsulation and oxidative damage in long-term in vivo applications. Poly(sulfobetaine methacrylate) - poly(SBMA) - zwitterionic hydrogels may represent more promising alternatives to minimize the FBR due to their ultra-low fouling features. Here, we tested and compared the poly(SBMA) zwitterionic hydrogel coating with the PEG coating in reducing adhesion and activation of pro-inflammatory and pro-fibrotic cells to polyimide surfaces, which are early hallmarks of FBR. We aimed to coat polyimide surfaces with a hydrogel thin film and analysed the release of a model drug from the hydrogel. We performed hydrogel synthesis, mechanical characterization and biocompatibility analysis. Cell adhesion, viability and morphology of human myofibroblasts cultured on PEG- and hydrogel-coated surfaces were evaluated through confocal microscopy-based high-content analysis (HCA). Reduced activation of pro-inflammatory human macrophages cultured on hydrogels was assessed as well as the hydrogel drug release profile. Because of its high hydration, biocompatibility, low stiffness and ultra-low fouling characteristics the hydrogel enabled lower adhesion and activation of pro-inflammatory and pro-fibrotic cells vs. polystyrene controls, and showed a long-term release of the anti-fibrotic drug Everolimus. Furthermore, a polyimide surface was successfully coated with a hydrogel thin film. Our soft zwitterionic hydrogel could outperform PEG as more suitable coating material of neural electrodes for mitigating the FBR. Such poly(SBMA)-based biomaterial could also be envisioned as long-term delivery system for a sustained release of anti-inflammatory and anti-fibrotic drugs in vivo

Our aim was to compare polylevolactic acid screws with titanium screws when used for fixation of the distal tibiofibular syndesmosis at mid-term follow-up. A total of 168 patients, with a mean age of 38.5 years (18 to 72) who were randomly allocated to receive either polylevolactic acid (n = 86) or metallic (n = 82) screws were included. The Baird scoring system was used to assess the overall satisfaction and functional recovery post-operatively. The demographic details and characteristics of the injury were similar in the two groups. The mean follow-up was 55.8 months (48 to 66). The Baird scores were similar in the two groups at the final follow-up. Patients in the polylevolactic acid group had a greater mean dorsiflexion (p = 0.011) and plantar-flexion of the injured ankles (p < 0.001). In the same group, 18 patients had a mild and eight patients had a moderate foreign body reaction. In the metallic groups eight had mild and none had a moderate foreign body reaction (p <  0.001). In total, three patients in the polylevolactic acid group and none in the metallic group had heterotopic ossification (p = 0.246). We conclude that both screws provide adequate fixation and functional recovery, but polylevolactic acid screws are associated with a higher incidence of foreign body reactions. Cite this article: Bone Joint J 2014;96-B:548–54

The Masquelet technique is a variable method for treating critical-sized bone defects, but there is a need to develop a technique for promoting bone regeneration. In recent studies of bone fracture healing promotion, macrophage-mesenchymal stem cell (MSC) cross-talk has drawn attention. This study aimed to investigate macrophage expression in the induced membrane (IM) of the Masquelet technique using a mouse critical-sized bone defect model. The study involved a 3-mm bone defect created in the femur of mice and fixed with a mouse locking plate. The Masquelet (M) group, in which a spacer was inserted, and the Control (C) group, in which the defect was left intact, were established. Additionally, a spacer was inserted under the fascia of the back (B group) to form a membrane due to the foreign body reaction. Tissues were collected at 1, 2, and 4 weeks after surgery (n=5 in each group), and immunostaining (CD68, CD163: M1, M2 macrophage markers) and RT-qPCR were performed to investigate macrophage localization and expression in the tissues. The study found that CD68-positive cells were present in the IM of the M group at all weeks, and RT-qPCR showed the highest CD68 expression at 1 week. In addition, there was similar localization and expression of CD163. The C group showed lower expression of CD68 and CD163 than the M group at all weeks. The B group exhibited CD68-positive cells in the fibrous capsule and CD163-positive cells in the connective tissue outside the capsule, with lower expression of both markers compared to the M group at all weeks. Macrophage expression in IM in M group had different characteristics compared to C group and B group. These results suggest that the IM differs from the fibrous capsules due to the foreign body reaction, and the macrophage-MSC cross-talk may be involved in Masquelet technique

Question: Is the histopathological response of the peri-prosthetic tissue to metal-on-metal bearings comparable to the well studied reactions to polyethylene debris or do specific reactions exist and are theses reactions depending on the implant design?. Methods: Periprosthetic tissue samples from 19 THR and Hip Resurfacings (11 Birmingham Hip Resurfacings, 2 (historical)McMinn Hybrid Hip Resurfacings, 5 MetaSUL THR) with a variety of failure mechanisms were examined histopathologically and immunohistochemically. Results: Only the samples of the (historical) McMinn Hybrid resurfacings showed a stronger histiocytic foreign body reaction and a higher grade metallosis. In all other cases only a mild if any histiocytic foreign body reaction was found. Additionally a chronic lymphoplasmacellular tissue reaction was present in all cases. 3 cases showed a higher grade chronic lymphoplasmacellular inflammatory tissue response comparable to a specific immune reaction. Discussion: We found two different response mechanisms of the periprosthetic tissues to metal-on-metal bearings. In addition to the classic histiocytic foreign body reaction which was usual mild and only stronger in cases with a greater amount of metallic debris a lymphoplasmacellular inflammatory reaction usually was present but did not reach the level of inflammatory alterations associated with potential osteolysis and was not related to the implant or amount of wear. In 3 of our 19 cases the lymphoplasmacellular infiltration was stronger and comparable to a specific immune reaction. The significance of the specific immune reaction could not be further explained because a correlation to the failure mechanisms was not detectable

Recent researches indicate that both M1 and M2 macrophages play vital roles in tissue repair and foreign body reaction processes. In this study, we investigated the dynamics of M1 macrophages in the induced membrane using a mouse femur critical-sized bone defect model. The Masquelet method (M) and control (C) groups were established using C57BL/6J male mice (n=24). A 3mm-bone defect was created in the right femoral diaphysis followed by a Kirschner wire fixation, and a cement spacer was inserted into the defect in group M. In group C, the bone defect was left uninserted. Tissues around the defect were harvested at 1, 2, 4, and 6 weeks after surgery (n=3 in each group at each time point). Following Hematoxylin and eosin (HE) staining, immunohistochemical staining (IHC) was used to evaluate the CD68 expression as a marker of M1 macrophage. Iron staining was performed additionally to distinguish them from hemosiderin-phagocytosed macrophages. In group M, HE staining revealed a hematoma-like structure, and CD68-positive cells were observed between the spacer and fibroblast layer at 1 week. The number of CD68-positive cells decreased at 2 weeks, while they were observed around the new bone at 4 and 6 weeks. In group C, fibroblast infiltration and fewer CD68-positive cells were observed in the bone defect without hematoma-like structure until 2 weeks, and no CD68-positive cells were observed at 4 and 6 weeks. Iron staining showed hemosiderin deposition in the surrounding area of the new bone in both groups at 4 and 6 weeks. The location of hemosiderin deposition was different from that of macrophage aggregation. This study suggests that M1 macrophage aggregation is involved in the formation of induced membranes and osteogenesis and may be facilitated by the presence of spacers

Reducing wear of endoprosthetic implants is still an important goal in order to increase the life time of the implant. Endoprosthesis failure can be caused by many different mechanisms, such as abrasive wear, corrosion, fretting or foreign body reactions due to wear accumulation. Especially, modular junctions exhibit high wear rates and corrosion due to micromotions at the connection of the individual components. The wear generation of cobalt-chromium-molybdenum alloys (CoCrMo) is strongly influenced by the microstructure. Therefore, the aim of this work is to investigate the subsurface phase transformation by deep rolling manufacturing processes in combination with a “sub-zero” cooling strategy. We analyzed the influence on the phase structure and the mechanical properties of wrought CoCr28Mo6 alloy (ISO 5832-12) by a deep rolling manufacturing process at various temperatures (+25°C,-10°C,-35°C) and different normal forces (700N and 1400N). Surface (S. a. ,S. z. ) and subsurface characteristics (residual stress) as well as biological behavior were investigated for a potential implant application. We showed that the microstructure of CoCr28Mo6 wrought alloy changes depending on applied force and temperature. The face centered cubic (fcc) phase could be transformed to a harder hexagonal-close-packed (hcp) phase structure in the subsurface. The surface could be smoothed (up to S. a. = 0.387 µm±0.185 µm) and hardened (≥ 700 HV 0.1) at the same time. The residual stress was increased by more than 600% (n=3). As a readout for metabolic activity of MonoMac (MM6) and osteosarcoma (SaOS-2) cells a WST assay (n=3) was used. The cells showed no significant negative effect of the sub-zero manufacturing process. We showed that deep rolling in combination with an innovative cooling strategy for the manufacturing process has a great potential to improve the mechanical properties of CoCr28Mo6 wrought alloy, by subsurface hardening and phase transformation for implant applications

For chondral damage in younger patients, surgical best practice is microfracture, which involves drilling into the bone to liberate the bone marrow. This leads to a mechanically inferior fibrocartilage formed over the defect as opposed to the desired hyaline cartilage that properly withstands joint loading. While some devices have been developed to aid microfracture and enable its use in larger defects, fibrocartilage is still produced and there is no clear clinical improvement over microfracture alone in the long term. Our goal is to develop 3D printed devices, which surgeons can implant with a minimally invasive technique. The scaffolds should match the functional properties of cartilage and expose endogenous marrow cells to suitable mechanobiological stimuli in-situ, in order to promote healing of articular cartilage lesions before they progress to osteoarthritis, and rapidly restore joint health and mobility. Importantly, scaffolds should direct a physiological host reaction, instead of a foreign body reaction, associated with chronic inflammation and fibrous capsule formation, negatively influencing the regenerative outcome. Our novel silica/polytetrahydrofuran/polycaprolactone hybrids were prepared by sol-gel synthesis and scaffolds were 3D printed by direct ink writing. 3D printed hybrid scaffolds with pore channels of ~250 µm mimic the compressive behaviour of cartilage. Our results show that these scaffolds support human bone marrow stem/stromal cell (hMSC) differentiation towards chondrogenesis in vitro under hypoxic conditions to produce markers integral to articular cartilage-like matrix evaluated by immunostaining and gene expression analysis. Macroscopic and microscopic evaluation of subcutaneously implanted scaffolds in mice showed that scaffolds caused a minimal resolving inflammatory response. Our findings show that 3D printed hybrid scaffolds have the potential to support cartilage regeneration. Acknowledgements: Authors acknowledge funding provided by EPSRC grant EP/N025059/1

Screw fixation is an established method for anterior cruciate ligament (ACL) reconstruction, although with a high rate of implant-related complications. An allograft system for implant fixation in ACL reconstruction, the Shark Screw ACL (surgebright GmbH) could overcome some of the shortcomings of bioabsorbable screws, such as foreign body reaction, need for implant removal and imaging artefacts. However, it needs to provide sufficient mechanical stability. Therefore, the aim of this study was to investigate the biomechanical stability, especially graft slippage, of the novel allograft system versus a conventional bioabsorbable interference screw (BioComposite Interference Screw; Arthrex Inc.) for tibial implant fixation in ACL reconstruction. Twenty-four paired human proximal tibiae (3 female, 9 male, 72.7 ± 5.6 years) underwent ACL reconstruction. The quadrupled semitendinosus and gracilis tendon graft were fixed in one specimen of each pair using the allograft fixation system Shak Screw ACL and the contralateral one using an interference screw. All specimens were cyclically loaded at 1 Hz with peak load levels monotonically increased from 50 N at a rate of 0.1 N/cycle until catastrophic failure. Relative movements of the graft versus the tibia were captured with a stereographic optical motion tracking system (Aramis SRX; GOM GmbH). The two fixation methods did not demonstrate any statistical difference in ultimate load at graft slippage (p = 0.24) or estimated survival at slippage (p = 0.06). Both, the ultimate load and estimated survival until failure were higher in the interference screw (p = 0.04, and p = 0.018, respectively). Graft displacement at ultimate load reached values of up to 7.2 mm (interference screw) and 11.3 mm (Shark Screw ACL). The allograft screw for implant fixation in ACL reconstruction showed similar behavior in terms of graft slippage compared to the conventional metal interference screw but underperformed in terms of ultimate load. However, the ultimate load may not be considered a direct indicator of clinical failure

Menisci are crucial structures for knee homeostasis: they provide increase of congruence between the articular surfaces of the distal femur and tibial plateau, bear loading, shock absorption, lubrication, and proprioception. After a meniscal lesion, the golden rule, now, is to save as much meniscus as possible: only the meniscus tissue which is identified as unrepairable should be excised and meniscal sutures find more and more indications. Several different methods have been proposed to improve meniscal healing. They include very basic techniques, such as needling, abrasion, trephination and gluing, or more complex methods, such as synovial flaps, meniscal wrapping, or the application of fibrin clots. Basic research of meniscal substitutes has also become very active in the last decades. The features needed for a meniscal scaffold are: promotion of cell migration, it should be biomimetic and biocompatible, it should resist forces applied and transmitted by the knee, it should slowly biodegrade and should be easy to handle and implant. Several materials have been tested, that can be divided into synthetic and biological. The first have the advantage to be manufactured with the desired shapes and sizes and with precise porosity dimension and biomechanical characteristics. To date, the most common polymers are polylactic acid (PGA); poly-(L)-lactic acid (PLLA); poly- (lactic-co-glycolic acid) (PLGA); polyurethane (PU); polyester carbon and polycaprolactone (PCL). The possible complications, more common in synthetic than natural polymers are poor cell adhesion and the possibility of developing a foreign body reaction or aseptic inflammation, leading to alter the joint architecture and consequently to worsen the functional outcomes. The biological materials that have been used over time are the periosteal tissue, the perichondrium, the small intestine submucosa (SIS), acellular porcine meniscal tissue, bacterial cellulose. Although these have a very high biocompatibility, some components are not suitable for tissue engineering as their conformation and mechanical properties cannot be modified. Collagen or proteoglycans are excellent candidates for meniscal engineering, as they maintain a high biocompatibility, they allow for the modification of the porosity texture and size and the adaptation to the patient meniscus shape. On the other hand, they have poor biomechanical characteristics and a more rapid degradation rate, compared to others, which could interfere with the complete replacement by the host tissue. An interesting alternative is represented by hydrogel scaffolds. Their semi-liquid nature allows for the generation of scaffolds with very precise geometries obtained from diagnostic images (i.e. MRI). Promising results have been reported with alginate and polyvinyl alcohol (PVA). Furthermore, hydrogel scaffolds can be enriched with growth factors, platelet-rich plasma (PRP) and Bone Marrow Aspirate Concentrate (BMAC). In recent years, several researchers have developed meniscal scaffolds combining different biomaterials, to optimize the mechanical and biological characteristics of each polymer. For example, biological polymers such as chitosan, collagen and gelatin allow for excellent cellular interactions, on the contrary synthetic polymers guarantee better biomechanical properties and greater reliability in the degradation time. Three-dimensional (3D) printing is a very interesting method for meniscus repair because it allows for a patient-specific customization of the scaffolds. The optimal scaffold should be characterized by many biophysical and biochemical properties as well as bioactivity to ensure an ECM-like microenvironment for cell survival and differentiation and restoration of the anatomical and mechanical properties of the native meniscus. The new technological advances in recent years, such as 3D bioprinting and mesenchymal stem cells management will probably lead to an acceleration in the design, development, and validation of new and effective meniscal substitutes

Millions of medical devices made of synthetic or modified natural materials all trigger a similar reaction—the foreign body reaction. Biocompatibility, for materials that pass routine cytoxicity assays, is largely associated with a mild foreign body reaction. I.e. a thin, avacular, collagenous, non-adherent foreign body capsule. The implant is incorporated into a dead-zone of acellular scar. The contemporary tissue engineering paradigm would suggest that synthetic polymers and scaffolds lacking cellular, biomolecule or biomimetic elements will give this same fibrotic, avascular healing reaction. In this talk, a synthetic biomaterial will be described that readily integrates into tissue and may stimulate spontaneous reconstruction of tissue. The material is fabricated by a process called sphere-templating and it can be made from many synthetic polymers including hydrogels, silicones and polyurethanes. All pores are identical in size and interconnected. Studies from our group have shown optimal healing (as suggested by extensive vascularity and minimal fibrosis) for spherical pores of 30–40 m size. The integrative healing noted is independent of biomaterial. Similar results are observed with sphere-templated silicone rubber and pHEMA hydrogel. In addition, surface chemical modification of the hydrogel with carbonyl diimidazole, or immobilisation on the hydrogel of collagen I or laminin did not change the healing response. Also, good healing results have been seen upon implantation in skin (subcutaneous, percutaneous), heart muscle, sclera, skeletal muscle, bone and vaginal wall. We consistently find the pore spaces heavily populated by monocytic cells that stain for macrophage cell surface markers. However, at long implantation times (16 or more weeks), the ability to stain for macrophage surface markers decreases. It could be possible that these cells populating the implants are differentiating into other tissues. Thus, such materials may represent a path to cell-free tissue engineering. Others have seen similar healing results, via completely different materials strategies, generally involving biological molecules. The in vivo results from our group and related results from other groups suggest we are on the cusp of a revolution in healing, biomaterials integration and tissue reconstruction. Also, the boundaries between biomaterials and tissue engineering continue to blur

Aims: Fracture repair with biodegradable implants (BDI) avoids implant removal, associated with improved patientñs beneþt and reduced health cost. However, foreign body reactions around the implants have been reported. Furthermore, data on in-vivo degradation of BDI remain limited on animal trials or human case reports. Therefore, the purposes of this prospective study were 1) to evaluate clinical and radiological results and side effects of biodegradable rods used to treat radial head fractures and 2) to assess the role of magnetic resonance imaging (MRI) to visualise BDI and their degradation. Methods: 31 displaced radial head fractures in 31 patients (median age of 30 (20–59) years) were þxed with PDLLA-rods. Clinical and radiological results were evaluated after a median follow-up of 18 (3–41) months (Broberg-Morrey score). MRI (1.5 Tesla) was applied in 14 patients. Results: The average Broberg-Morrey score was 90.5; 97% of the cases were classiþed as excellent or good, 3% as fair. Patientñs satisfaction was rated as excellent or good in 93%, as fair in 7%. No foreign body reaction was observed. In all 14 MRI cases localization, size and type of BDI were sufþciently depictable. Signiþcantly changed signal intensity, potentially representing material degradation, was not observed throughout a maximal follow-up interval of three years. Conclusions: More than 93% excellent or good subjective and objective results conþrm the advantageous use of PDLLA-rods for þxation of radial head fractures. MRI proved to be an appropriate non-invasive method to visualise type and size of BDI, whereas signs of implant degradation have not been seen after a median F/U of 18 months

Introduction Rotator cuff degeneration is considered to be a major factor in the pathogenesis of rotator cuff tendon tear. Degenerative weakening of the rotator cuff can result in irreversible complete cuff-tear arthropathy syndrome. Recently a porcine small intestinal submucosa (SIS) has been approved by TGA as biological implant for the repair of rotator cuff tendon tear. The aims of this study are to evaluate the safety and efficacy of SIS. Methods A commercial brand of SIS was examined by histology and PCR technique. The material was implanted into mice and rabbits for the evaluation of biological reaction and inflammatory response. Next, we have used SIS to replace the rotator cuff tendon in rabbit (N=10) and compared to control (N=10). Histological examination was conducted at four and eight weeks after implantation. To further confirm if cells present in SIS material were of porcine origin, nested PCR for the amplification of DAP12 gene was used. Results Fresh SIS membrane before implantation contain multiple layers of spindle-shaped cells mixed with a small population of round-shaped cells. Chloroacetate esterase staining showed that the round-shaped cells are positive, indicating that they are mast cells. The tissue architecture of SIS mimics tendon structure as evidenced by H & E staining. The SIS membrane contained porcine DNA materials. Subcutaneous implant of SIS in mice (by six) for up to seven days showed no obvious inflammatory response or foreign body reaction. The result demonstrated that SIS has remained in the region and mixed with regenerative fibrous tissue after eight weeks. In some cases there was a massive recruitment of lymphocytes along the surface of membrane. However, no foreign body reactive giant cells were observed. Conclusions The result of this study indicated that SIS contains porcine cells and nucleic acid, which contradicts current views that SIS is a cell free biomaterial. Although no foreign body reaction of SIS was observed, SIS implant may cause chronic inflammation. Further studies should be conducted to confirm the clinical efficacy of SIS implant for rotator cuff tendon tear

[Introduction]. In 1995, Muller reported on the improvement of metal-on-metal (MOM) bearing over the existing metal-on-polyethylene (MOP) articulations which demonstrated more rapid wear together with granulomatous foreign body reactions, damage of periarticular bony and soft tissues and associated expansile psoas bursal masses. He suggested that adequate lubrication together with improved material properties and manufacturing technologies would bring to the market a superior device with greater longevity. We wish to present our experience with a modern version of a MOM bearing. [Material and Methods]. Between April 2008 and February 2012, we implanted 160 MOM THA with head diameters of 38–50 mm in 139 patients (21 males and 118 females). Their ages were 40–86 years (avg. 63.6 yrs). Follow up was 9 to 53 months post implantation (avg. 28 months). All implants were manufactured by one company (Wright Medical Technology, Arlington, TN, USA). The stems were of a standard titanium-aluminum alloy, either 45 ANCA-FIT or 115 PROFEMUR Z non-cemented stems. Acetabular components were all CONSERVE PLUS cobalt-chromium monoblock shells. Heads were also fabricated out of cobalt-chromium alloy, with modular junctions. Patients with complaints of groin pain and/or swelling or hip instability underwent MRI examination in order to detect the presence of fluid collections or soft tissue masses (Fig. 1 and 2). The statistical correlation between abnormal findings on MRI and age, gender, head diameter, component position and duration post-surgery was performed. [Results]. 27 hips in 23 patients (16.9%) were found to have either a fluid collection or “pseudotumor”. These were in 2 males and 21 female patients. There were 19 males and 97 females without complaints who did not undergo MRI examination. There was no difference in age between these two groups of patients (63.1 vs. 63.7 yrs). There was no difference in duration from the time of implantation, but there was an early presentation of symptomatic pseudotumor. There appeared to be a significant difference between the mean head diameter of the two groups, 41.8 mm and 44.2 mm respectively. There was no statistical difference between the two groups with regard to implant orientation: cup inclination 18–70 degrees (40.4 vs. 43.8 degrees); cup anteversion −13−49 degrees (14.0 vs. 15.0 degrees); stem anteversion 2–48 degrees (20.2 vs. 23.1 degrees); and stem offset 17.5–56.2 mm (38.2 vs. 37.8 mm). [Discussion]. In this study, it is important to emphasize that the appearance of symptoms and development of a pseudotumor occurred early after a MOM THA in some patients. It may represent a hypersensitivity to materials implanted. However, the possibility that this may represent a foreign body reaction to particulate debris produced by articulating surfaces much like that seen with alternative material such as MOP, reflective of wear, insufficient lubrication or other causes. In this regard, our study suffers from the limitation that serum levels of chromium and cobalt were not obtained from symptomatic patients. Nor were these patients skin tested for hypersensitivity to these materials. Also it will be important to subject all patients to MRI examination to evaluate the possibility of “silent” fluid collections and pseudotumors

Introduction: Hip simulator tests, analyses of retrieved components as well as radiostereometric measurements revealed that cups made of highly linked polyethylene show a much better wear performance than cups of conventional polyethylene. However, to the best of our knowledge, histomorphological studies of tissues from the surrounding of highly cross – linked polyethylene components have not been reported yet. The aim of this study was to examine such tissues for particles, released from highly cross – linked polyethylene cups and to compare the findings with those of conventional polyethylene. Material and methods: So far, periprosthetic tissues retrieved at revisions of 11 total hip endoprostheses with highly cross – linked polyethylene cups could be analysed. The revisions became necessary 3 to 50 months after implantation because of cup loosening (4), stem loosening (1), infection (3), periprosthetic fracture of the femur (1), multiple dislocations (1) and periarticular ossification (1). The findings were compared with those of 5 artificial joints (2 ABG, 2 Müller Cup older design, 1 Metalback pressfit) with conventional polyethylene cups and 54 to 231 months of function. 5 μm sections were made from the tissues and conventionally stained with HE and van Gieson. Morphometric measurements were done using objectives 10 and 40 of an Olympus microscope and the ‘Analysis’ program of Soft Ware Imaging GmbH. In the Durasul TM – cases, the total amount and the total area of particles were ascertained while in the cases used for comparison only random CX 40 samples could be measured because of the much higher content of particles. Results: The DurasulTM cases showed in contrast to the cases with conventional polyethylene cups, no distinct foreign body reaction. In four of the DurasulTM cases no particles could be detected at all and in the remaining seven particles could be found only in a few areas. Their number per section was between 6 and 1208, their total area per mm. 2. section ranged between 0,03 and 6,99 × 10 5.mm. 2. In the conventional polyethylene cases the number of particles per section was between 2832 and 71447, their total area per mm. 2. section ranged between 1,06 and 25,91 × 10 3mm. 2. ! The average size of the DurasulTM particles was clearly bigger than the size of the conventional Polyethylene. Discussion: The measurements in tissues of early revisions show that DurasulTM releases much less particles into the surrounding than PE and cause rather no foreign body reaction. Accordingly, the burden of the tissue with polyethylene debris is much lower while the particle size is bigger with DurasulTM than with PE

Introduction: It is well known that the fate of biomaterials is determined by the distribution of proteins attached to the surface from the initial contact with blood or serum. This profile determines wether a material is inert, creates a foreign body response or is bioactive. Bioinert materials, such as polyethylene completely denature surface proteins, whilst materials inducing inflammatory responses are predisposed to complement protein attachment. Bioactive materials such autologous tissue grafts adsorb, but do not denature serum proteins such as fibronectin and Von Willebrand’s factor. This does not interfere with the healing cascade. This aim of this study is to prepare a synthetic bone graft substitute that activates the body’s autologous healing cascade by activating platelets, without activating a complement response through the controlled adsorption of serum proteins. Methods: Polymers composed of varied concentration of acrylic acid (AA) and comonomers (methyl, ethyl and butyl methacrylates (MMA, EMA, BMA)) were prepared in glass vials by free radical polymerisation. Fresh blood was collected from a healthy donor and pipetted immediately into each chamber. Glass was used as a control. The chambers were incubated at 37o C for 2 hours. The surface morphology was examined using Scanning Electron Microscopy (SEM). Concentration of complement protein C5a and prothrombin fragments 1 and 2 were determined using commercial ELISA kits. Foreign body reaction (FBR) initiated by the biomaterial was estimated by counting leukocytes on clot sections using immunofluorescence. Results: Extent of coagulation was correlated with plasma concentrations of Prothrombin fragments 1 and 2. These measurements show blood incubated with various polymers composed of different comonomers all promoted the formation of blood clots. It was found that the leukocyte population towards the interface of clot and polymer (AA:MMA) decreased with increasing surface acid concentration (65%AA:MMA 30 leukocytes/0.25mm2, glass 70 leukocytes/0.25mm2 (p< 0.05)). FBR is induced by the activation of complement system. The percentage of C5a concentration detected in blood incubated with various polymers composed of different comonomers relative to normal serum level of C5a (35ng/mL). No significant elevations of C5a were measured from polymer 65% AA:MMA and 65% AA:EMA. Glass induced vigorous complement response as expected. The synergistic combination of surface acid concentration and comonomers had a significant effect on extent of FBR. Increased acid concentration resulted in decreased C5a level with MMA and ET but increased level with BMA. Discussion: The functional groups exposed on the surface of a material influence whether leukocyte or platelet activation is responsible for the subsequent physiological response. By modifying the combinations of surface acid concentrations and comonomers, we show that a biomaterial with an appropriate surface chemistry promotes the platelet plug formation and coagulation but down regulated foreign body reaction. This study shows that that a biomaterial with the appropriate surface chemistry to evoke the same coagulation response as damaged tissue, mediated through platelet activation and intrinsic and extrinsic coagulation, initiates the initial pathways of the bone healing cascade. This material is a realistic candidate for biomaterial induced bone regeneration

Ceramic-on-ceramic bearing is an attractive alternative to metal-on-polyethylene bearing due to the unique tri-bological advantages of alumina. However, despite the long-term satisfactory results obtained so far in the vast majority of patients, failure may occur in a few cases. Clinical, radiographic, laboratory and microbiological data of 30 consecutive subjects with failed alumina-on-alumina total hip arthroplasties (THA) were analyzed to define if foreign body reaction to wear debris may be responsible for periprosthetic bone resorption, as in conventional metal-to-polyethylene bearings. In all cases, clinical and radiographical material was reviewed, retrieved implants were examined, and histology of periprosthetic tissues was analyzed. Massive osteolysis was never observed. Apart from 5 five patients for which revision surgery was necessary due to the occurrence of late infection, in all other cases failure had occurred due to secondary implant instability (as in the case of screwed sockets, 19 cases) or to malpositioning of the implant (5 cases). One patient suffered from chronic dislocation. In the vast majority of cases, ceramic wear debris was absent or scarce, and did not induce any tissue reaction. In a few cases with severe wear, debris was evident in clusters of perivascular macrophages, notably in the absence of foreign body multinucleated cells, confirming the excellent biocompatibility of ceramics. These findings indicate that wear debris and peri-prostetic bone resorption were the effect rather than the cause of failure, differently from revised metal-on-polyethylene bearings, in which foreign body cell reaction is the main pathogenetic mechanism of failure. On the contrary, mechanical problems, due to incorrect surgical technique or to inadequate prosthetic design, may cause instability of the implant, in turn resulting in wear debris production and moderate if any biological reaction

The retear of the rotator cuff (RC) repair is a significant problem. Usually it is the effect of poor quality of the tendon. The aim was to evaluate histologically two types of RC reconstruction with scaffold. We have chosen commercially available scaffold polycaprolactone based poly(urethane urea). Rat model of supraspinatus tendon injury was chosen. There were four study groups: RC tear (no repair) (n=10), RC repair (n=10), RC repair augmented with scaffold (n=10) and RC reconstruction with scaffold interposition between tendon and bone (n=10). The repairs were investigated histologically at 6 and 16 weeks. The results in two groups in which scaffold was used had significantly better scores at 6 weeks comparing to non-scaffold groups (16,4±3, 17,3± 2,8 vs. 12,5±4,4, 13,8±1,4 respectively) and 16 weeks (23±1,9, 22,8±1,6 vs. 13,8±3,3, 14,9± 3,8 respectively). Results in two scaffold groups improved between 6 and 16 weeks. Signs of foreign body reaction against scaffold were not observed. Application of scaffold to strengthen the repair site and bridging of the tendon defect improved healing of the RC repair in animal model at 6 and 16 weeks. The quality of reconstructed tendon improved over time. No such effect was observed in groups without repairs and isolated repairs were performed

Tissue engineering is a promising approach to regenerate damaged skeletal tissues. In particular, the use of injectable hydrogels alleviates common issues of poor cell viability and engraftment. However, uncontrolled cell fate, resulting from unphysiological environments and degradation rates, still remain a hurdle and impedes tissue healing. We thus aim at developing a new platform of injectable hyaluronic acid (HA) hydrogels with a large panel of properties (stiffness, degradation…) matching those of skeletal tissues. Hence, HA with different molecular weights were functionalized with silylated moieties. Upon injection, these hydrogels formed through a sol-gel chemistry within 5 to 20 minutes in physiological conditions, as demonstrated by rheological characterization. By varying the crosslinking density and concentration, we obtained hydrogels spanning a large range of elastic moduli (E = 0.1–20 kPa), similar to those of native ECMs, with tunable biodegradation rates (from 24 hours to > 50 days) and swelling ratios (500 to 5000% (w/w)). Cell viability was confirmed by Live/Dead assays and will be completed by in vivo subcutaneous implantations in mice to study the foreign body reaction and degradation rate. We further developed hybrid HA/biphasic calcium phosphate granules hydrogels and demonstrated a strong mechanical reinforcement (E = 0.1 MPa) and a faster relaxation behaviour (τ. 1/2. < 400s), with similar degradation rates. Ongoing in vitro differentiation assays and in vivo implantations in a rabbit femur model will further assess their ability to drive bone regeneration. Collectively, these results suggest that this hydrogel platform offers promising outcomes for improved strategies in skeletal tissue engineering

Recent studies about hip stability after total hip arthroplasties (THA) concerned differences regarding bearings: ceramic on ceramic (CoC) presenting less dislocations on the long term compared to metal or ceramic on polyethylene. The hypothesis is a difference in the healing process of periarticular tissues, with a stronger fibrous tissue for the first one, and more foreign body reaction, joint effusion with the others. NMR Imaging of the pelvis showing both hips using novel MR MAVRIC program for metal artefacts suppression, were performed in 10 patients, 15 THA and 2 non-pathological contralateral hips. Eight hips had CoC bearings, 3 of which were impacted cementless bulky ceramic implant, and 5 had a metal back. 7 hips had CoP bearings, 4 of which were cemented. Native capsules showed a mean thickness of 6.6mm. For CoC bearings, capsule thickness ranged from 7mm to 9.6 mm with a mean thickness of 8mm. For CoP bearings, capsule thickness ranged from 3mm to 8.4mm, with a mean thickness of 6.1mm. Neocapsule appeared clearly in all COC bearings observed, while for CoP, sometimes it was less dense with fatty aspect, 3 hips out of 7 having a very thin capsule under 4mm. It is possible to observe and quantify new capsule after THR and measure differences although not significant regarding bearings on limited number of samples. More patients might be included, but the tendencies observed here might explain better long term stability in vivo observed with Coc

Adverse reaction to metal debris (ARMD) is well recognised as a complication of large head metal on metal total hip replacement (THR) leading to pain, bone and tissue loss and the need for revision surgery. An emerging problem of trunnionosis in metal on polyethylene total hip replacements leading to ARMD has been reported in a few cases. Increased metal ion levels have been reported in THR's with a titanium stem and a cobalt chrome head such as the Accolade-Trident THR (Stryker). We present 3 cases of ARMD with Accloade-Trident THR's with 36mm cobalt chrome head and a polyethylene liner. Metal ion levels were elevated in all three patients (cobalt 10.3 – 161nmol/l). Intraoperative tissue samples were negative for infection and inflammatory markers were normal. Abnormal fluid collections were seen in all three cases and bone loss was severe in one patient leading to a proximal femoral replacement. Histology demonstrated either a non-specific inflammatory reaction in a case which presented early or a granulomatous reaction in a more advanced case suggesting a local foreign body reaction. All patients had improved symptoms post-operatively. 1 patient who had staged bilateral Accolade-Trident THR's required revision of both THR's. ARMD in metal on polyethylene THR's with a titanium stem represents a potential emerging problem. Further studies are required to assess whether these occurrences are rare or represent the tip of an iceberg

Total joint arthroplasty is the most significant advance in the treatment of end-stage arthritic disease of major joints. Despite the clinical success of this surgical procedure, however, some total joint prostheses fail, and although a failed prosthesis can be replaced, the results of revision arthroplasty are not as good as the first time. Studying the failed prosthesis and the associated bone and soft tissues provides insight into the causes of failure. Most prosthetic failures are the result of structural limitations of the implant components. Although material failure may be sudden, a much more common cause is gradual aseptic loosening of the prostheses. Aseptic loosening is caused by both mechanical (gradual loss of material by wear) and biological (osteoclastic resorption of adjacent bone) factors. Wear particles induce a foreign body reaction characterized by a pseudomembrane composed of granulomatous tissues including macrophages, fibroblasts, giant cells, and osteoclasts in addition to debris particles. The extent of this response is driven by the number, size, composition, surface area, and types of particles present. Although there are differences in the relative local toxicity of each of these particles, the end result is the same. These mechanical and biological factors are unavoidable, and the success of a total joint prosthesis depends on the rate with which they occur. Polyethylene wear particles (1–200 ?) are the primary cause of loosening. They are strongly birefringent under polarized light microscopy. Smaller particles are phagocytized by histiocytes, whereas larger particles are surrounded by foreign body giant cells. Fragmentation of PMMA may also cause particulate debris. The presence of these particles (30–100 ?) may be deduced by empty spaces into the soft tissues, often bordered by foreign body giant cells, since PMMA is dissolved by xylene during routine histological techniques. Metal oxides form on the surface of chrome-cobalt or titanium alloys due to an electrolytic process, and stresses on the surface of the metal shear the oxides into the surrounding tissues, causing a black pigmentation of the tissues. Histologically, the black deposits of oxidized metals are seen extracellularly as well as in the cytoplasm of histiocytes. In addition to oxidation, metal undergoes corrosion and, as a result, metal ions enter the soft tissues and the bloodstream. A ceramic-on-ceramic coupling generates a significantly lower amount of debris as compared to the conventional metal-on polyethylene solution. When present, ceramic debris cause a mild histiocytic reaction without giant cells and virtually no osteoclastic bone resorption. There are various secretory proteins at the interfacial membrane that can affect bone turnover, including the cytokines IL-1, IL-6, Il-10, and TNF-a. Other factors involved with bone resorption include the enzymes responsible for catabolism of the organic component of bone, such as MMPs. Prostaglandins, in particular PGE2, are also known to be important intercellular messengers in the osteolytic cascade. More recently, several mediators known to be involved in stimulation or inhibition of osteoclast differentiation and maturation, such as RANKL and osteoprotegerin, have been suggested as key factors in the development and progression of osteolysis. Infection around a prosthesis also causes loosening in approximately 1–5% of cases. Total joint prostheses become infected by two mechanisms, wound contamination at the time of surgery by Staph. aureus or Staph.epidermidis, and late hematogenous spread of organisms (Staphylo- and Streptococci, E. Coli, Pseudomonas, and anaerobes). The following factors facilitate bacterial growth. First, reaming and sawing, as well as PMMA polymerization, cause necrosis of necrotize bone adjacent to the implant, and such nonvascularized area permits bacteria to grow, safe from circulating host defenses. Second, a highly hydrated matrix of extracellular polymeric substances (biofilm) is formed that defends bacteria from antibiotics and phagocytosis. Third, some metals, such as nickel or cobalt, may depress macrophage function. The distinguishing histologic features of an infected prosthesis is an acute inflammatory reaction: a finding of > 5 PMN or of > 50 lymphocytes/hp field are presumptive for infection. Because some low-grade infections fail to stimulate an acute inflammatory reaction, they go undiagnosed until postoperative period when microbacterial culture results are available. To date, no single routinely used clinical or laboratory test has been shown to achieve ideal sensitivity and specificity for the diagnosis of prosthetic joint infection, and in most cases the diagnosis depends on a combination of clinical features, radiographic findings, and laboratory results. Intra-operative tissue cultures may be falsely negative because of prior antimicrobial exposure, a low number of organisms, inappropriate culture media, or atypical organisms. Conversely, cultures may be falsely positive because of contamination in the operating room, during transport, or in the laboratory. If the implant is removed, the entire prosthesis can be cultured. Moreover, because prosthetic joint infection is a biofilm-mediated infection, techniques that sample bacteria in biofilm, such as sonication or enzymatic treatment, may improve the diagnosis of prosthetic joint infection. More recently, molecular techniques are being used to detect nucleic acid in samples from infected patients even when conventional techniques are negative because of unusual microbial growth requirements or failure to grow after antimicrobial exposure or due to unfavourable environmental conditions. A disadvantage of such approach is its extreme sensitivity, leading to the possibility of false positive results. The clinical presentation of prosthetic joint infection may be indistinguishable from that of aseptic implant failure. In many cases, culture of granulomatous tissue around failed prostheses, preoperatively diagnosed as aseptically loosened, reveals the presence of bacteria that may per se significantly contribute to the recruitment, maturation and activation of osteoclasts and that superimpose to the foreign body reaction to wear debris. The presence of a smouldering infection in case of “aseptic” failure observed in revision arthroplasties. A systematic investigation on all retrieved implants is mandatory to define the precise role of each potential factor contributing to the pathogenesis of failure, in order to further improve the quality of care of patients having total joint arthroplasty

Background. Aseptic loosening of cemented femoral stems results from migration of wear particles along the bone-cement interface, producing a foreign body reaction. After cement insertion, blood back pressure can disrupt the bone-cement interface, enabling this spread of wear particles. Our study investigates whether altering timing and speed of stem insertion can reduce this risk. Methods. We inserted mock “C-Stem” femoral components (De Puy-Synthes), using Smartset HV cement (De Puy-Synthes) into artificial femora, fitted with proximal and distal pressure transducers. Cement insertion began two, three or four minutes after mixing. Cement pressures were then allowed to settle for one minute and the stems were then inserted over durations of 25, 60 or 90 seconds. Results. Quicker insertion led to high peak pressures; however insertion over 90 seconds at 4 and 5 minutes achieved more sustained pressures above blood back pressure. Slower insertion particularly improved proximal pressurisation. Furthermore when the stem was inserted over 90 seconds at 5 minutes then the cement pressures remained high after full insertion of the stem. Conclusions. Commonly, femoral stems are inserted rapidly. Our study demonstrates that by inserting the femoral stem more slowly, cement pressure can be maintained above blood back pressure for longer. We believe that after slower stem insertion, the higher cement viscosity enables the surgeon to maintain cement pressure, via the stem, sufficient to resist blood back pressure without inadvertently over inserting the stem. This safe and simple modification of cementing technique generates higher and more sustained cement pressures. Level of evidence. 3. Disclosures. Depuy-Synthes kindly provided the equipment used in the study. None of the authors received any payment or other benefits

Innominate Osteotomy first described by Salter is one of the commonest procedures performed for treatment of Developmental Dysplasia of the Hip (DDH) in children. We recently described a less invasive technique for Innominate Osteotomy, which significantly reduces the operation time without compromising outcome (J Pediatr Orthop B. 2010 Jul;19(4):318–22). As part of the evolution of this procedure we now routinely use bioabsorbable pins (INION OTPS PIN, made from co-polymers of L-lactic acid, D-lactic acid and trimethylene carbonate) instead of K-wires to secure the graft. We prospectively followed-up 120 consecutive cases done using bioabsorbale pins over a 2 year period. The surgical technique was as described in our less invasive innominate osteotomy paper. Average age at surgery was 24 months (18–52) with mean follow-up period of 15 months (6–24 months). The mean preoperative acetabular index was 36.2. o. Our results show a mean acetabular index of 18.7. o. (P< 0.0001) at latest follow-up with no loss of correction. We recorded three superficial wound infections (one MRSA), all resolved uneventfully. There was no foreign body reaction. The use of bioabsorbable pins eliminates the need for a second anaesthetic to remove the pins with significant cost benefit without compromising outcome

The pathologies of the hip (epiphisiolysis, Perthes, congenital dysplasia) cause invalidating outcomes in young patients. In the years many authors searched for the golden standard if total hip arthroplasty is necessary. From Smith-Petersen to McKee, to Amstutz the saving of the femoral neck has been the main objective, with the longevity of the system. Therefore the combination metal-metal has been used for articular components, because the friction of metallic components creates sub-micron metallic particles causing only minimal foreign body reactions andvery low wear rates. Our study group (Arthro Surgery Group) has implanted, from April 2003, 28 cementless resurfacing hip prosthesis with metal-metal articular components. The average follow-up has been of 6 months (from 3 months to 1 year). In all cases, the Harris Hip Score has been good or excellent (from 77 to 100), and radiographic exams didn’t show signs of radiolucence or resorption. This type of prosthesis allows moreover an minimum-invasive approach to the hip and a second line of defense in case of revision

We reviewed the results of 545 consecutive total hip replacements using a cementless non-coated high-density polyethylene acetabular component combined with a cemented Muller stem at five to 10 years. In all, 421 patients (445 hips) were available for review, 118 by questionnaire and 303 by examination and radiography. Of these, 86% had a good or excellent result. We found a high rate of radiological loosening of the cup after the sixth year, and a high rate of clinical loosening after the eighth year. Loosening was commoner in women, in younger patients and where a smaller size of acetabulum had been used. Calcar resorption was significantly related to loosening of the acetabulum. Loosening appeared to be mainly due to polyethylene debris produced by micro-movement of the acetabulum against the bone, which had resulted in a giant cell foreign body reaction and subsequent bone erosion. We have abandoned the use of this prosthesis and suggest that direct contact between bone and polyethylene should be prevented by a coating of metal or some other material

Aims: Aware of good results recently obtained with synthetic biodegradable polymers, in order to avoid problems seen with the use of metal implants, we adopted an intramedullary absorbable poly-l-lactic acid pins þxation in displaced metatarsal fractures. This paper reports on the results we have obtained. Methods: Eleven patients underwent open reduction and internal þxation of the fracture fragments using biodegradable pins of the following sizes: diameter 3,2 millimetre x length 5.0–6.0–7.0 millimetre. Clinical examination and X-ray controls were done three, six, twelve weeks and one year after surgery. In addition all patients were followed up with magnetic resonance imaging (MRI). Results: All patients operated healed in about 2 months without cast immobilization or prolonged rest. Serial radiographs showed good alignment of the bone and solid union at the fracture site. No inßammatory foreign body reactions or local infections were observed. Conclusions: SR-PLLA pins can provide a good stable metatarsal fracture þxation during bone healing but our study needs a longer-term follow- up to demonstrate their biologic value

Objectives: A stable shoulder is essential for proper elbow and hand function after oncologic resection of the shoulder girdle. We describe a surgical technique for replacing the shoulder joint capsule using synthetic mesh after resections of the shoulder girdle that resulted in gross intraoperative instability of the shoulder joint. Methods: 68 patients who underwent shoulder girdle resection between 1989 and 2006 were identified in our prospective database. This report focuses on nine patients whose shoulder joint was reconstructed with synthetic mesh. All patients were followed on a 3 monthly basis. Shoulder joint instability was determined from clinical records, database and radiographs. Results: Nine patients underwent shoulder joint reconstruction with synthetic mesh. One patient underwent a shoulder disarticulation within 30 days of the index surgery and was excluded from this rapport. No dislocations were noted during follow-up (range 3–48 months). Radiographs revealed an average vertical displacement of the humeral head compared to its original position of 0.7 cm (range 0–1.7 cm). There were two surgical complications. In one patient the humeral prosthesis migrated proximally and eroded through the skin requiring additional surgery. In another case erosion of the distal clavicle was noted. This was biopsied and foreign body reaction identified. Conclusions: Joint instability following major resections of the shoulder girdle is a source of morbidity and affects the function of the salvaged limb. Synthetic capsular reconstruction using Marlex mesh is a useful adjunct in patients where insufficient shoulder musculature and joint capsule remains after resection to allow for stable suspension of the upper limb

Fusion remains the standard of care and is associated with a high satisfaction rate. But.… fusion generally requires 6 weeks of restricted weight bearing or immobilization. Potential problems include 1) nonunion, 2) malunion, 3) sesamoid pain (from DJD), 4) late onset IP1 DJD. Complete joint replacement has been performed with a number of different designs since the early 1970's. The metal and poly designed implants are associated with a high failure rate, presumably from high shear loads, eccentric axial loads, poor fixation and bone stock problems. Resurfacing of both sides of the joint with a one piece silicone based crosslinked rubber {“silastic”} in rheumatoid patients appears to function better with use of metal grommets to reduce generation of particle debris and foreign body reaction. These silastic implants are still used by surgeons in select low-demand rheumatoid patients. Salvage after failure of any of these total joint replacements can be challenging because of loss of bone stock. 3 other methods are used to resurface the joint in severe OA: 1) resurfacing the proximal phalangeal side only, 2) resurfacing the metatarsal head only and 3) resurfacing the joint with and interposition arthroplasty. 1) advantage of the proximal phalangeal side resurfacing is simplicity of geometry; the disadvantage is disruption of the FHB attachment and the relative scarcity of severe cartilage damage at that side of the joint. 2) Advantage of the metatarsal head side for resurfacing is that is the typical location of the arthritic change; the disadvantage is potential interference with the sesamoid complex and bulkiness of fixation could lead to a more difficult salvage. 3) The advantage of interposition arthroplasty is the maintenance of bone stock; disadvantages include inconsistent local tissue and somewhat less predictable outcomes. In this talk I will focus primarily on the technique and results of a proximal phalangeal resurfacing approach for OA of the MTP1 joint

Introduction and Aims: Treatment of rotator cuff tendon tear presents a significant therapeutic challenge to surgeons. Porcine small intestinal submucosa (SIS) is a biomaterial approved by TGA and FDA for the repair of rotator cuff tendon tear. The aims of this study are to evaluate the safety and efficacy of SIS. Method: SIS purchased from DePuy Johnson & Johnson was examined by histology and PCR technique. The material was also implanted into mice and rabbits for the evaluation of biological reaction and inflammatory response. Porcine immunoreceptor DAP12 gene was used to examine if the material contained porcine DNA. Results: Fresh SIS membrane before implantation contains multiple layers of spindle-shaped cells mixed with a small population of round-shaped cells. Chloro-acetate esterase staining showed that the round-shaped cells are positive, indicating that they are mast cells. The tissue architecture of SIS mimics to tendon structure as evidenced by H& E staining. To further confirm if cells present in SIS material were porcine origin, nested PCR for the amplification of DAP12 gene was used. The result demonstrated that SIS membrane contain porcine DNA materials. Conclusion: SIS contains porcine cells and nuclei acid, which contradicts with current views that SIS is a cell-free biomaterial. Although no foreign body reaction of SIS was observed, SIS implant may cause chronic inflammation. Further studies should be conducted to confirm the clinical efficacy of SIS implant

1 . Implants of heterogenous cartilage are known to excite a foreign body reaction in host tissues. In these experiments the way such implants hinder the spread of ossification across a fracture gap was studied. A segment of bone and periosteum was excised from both fibulae in twelve young grivet monkeys, and epiphysial cartilage from a four-day- old rat was implanted in the gap on the left side. The repair processes were investigated at intervals up to twenty-eight weeks. 2. On both sides the gaps were filled by fibrous tissue growing in from the adjacent muscle, and four weeks elapsed before callus started to form. Thereafter ossification across the gap was active on the right side, with bony union in seven or eight weeks. 3. On the left side the implant was slowly resorbed by macrophages and giant cells. Ossification made little headway in the gap after the seventh week. Remains of the implant were found up to the end of the period covered by the experiment. The ends of the fragments were united by fibrous tissue. 4. The fifth to the eighth week seemed to be a critical period, during which the implant and its surrounding inflammatory cells hindered chondrification and ossification and prevented fusion of the masses of callus at the ends of the fragments. 5. It is concluded that anything that impedes callus formation across the fracture line during this critical period may lead to non-union

Although it is generally accepted that surgical treatment is the treatment of choice in chronic TA ruptures, therapeutic options are difficult. Traditional options include grafts (natural, allografts and synthetic grafts) and end to end repair. Natural grafts described include fascia lata and plantaris tendon. Synthetic materials such as Dacrongrafts, Marlex mesh and carbon fibers have been used. There are significant complications from graft and end to end repair. These include wound necrosis, delayed union, infection, foreign body reaction and devastating tissue loss. Also functional results are suboptimal after delayed reconstruction. Tendon transfer is another method that has been described for the treatment of these injuries. The tendons used were the flexor hallucis lomgus, flexor digitorum longus and the peronei . The FHL tendon transfer is considered advantageous to other tendon transfers because it is stronger, its axis of force is close to that of the TA and harvesting the tendon is easy and unlikely to cause any complications. We report excellent results following four operations in three patients treated with flexor hallucis longus tendon transfer for chronic Achilles tendon ruptures. All patients were on long term steroid treatment and an end to end repair would have been associated with a high complication rate. We believe that FHL transfer to replace the TA is a low morbidity alternative which gives good to excellent results in individuals with low to moderate demand

Aims: To investigate if coralline hydroxyapatite conduct bone formation in human spine. Methods: During revision surgery specimens were taken from the fusion mass from 13 patients, who received spinal instrumentation (Titanium alloy) and fusion with coralline hydroxyapatite. The age of patients at the time of revision surgery was 46±20 years. The time lapsed from the implantation of coralline hydroxyapatite (ProOsteon) was 11±11 months. The indication for revision was infection, pseudarthrosis, technical error, and pain related to hardware. The diagnosis for primary fusion was degenerative disease, spinal trauma and scoliosis. Coralline hydroxyapatite was applied on the posterior decorticated elements of the instrumented spine without any mixture with bone graft. Material from ten different places from the fusion mass was intraoperatively taken and the histological evaluation was made using the Hematoxylin-eosin histological stain. Results: There was a concentration of foreign-body like giant cells & development inflammatory granulomatous tissue around hydroxyapatite granules, which was gradually replaced by dense connective collagen tissue. Both inflammatory granulomatous and collagen tissue showed areas with foreign body reaction. In the cases, where bone has developed, the most initial finding was the presence of osteoblasts & apposition of osteoid in contact to hydroxyapatite granules. In a later phase, cancellous and lamellar bone has developed as a result of secondary ossification. Bone formation was observed in 11/15 cases. Conclusion: Coralline hydroxy-apatite conducts bone and osteoid formation around the implanted coralline hydroxyapatite granules in different areas of the human spine operated for different disorders

On hundred and ninety unselected patients, mean age 62(SD12.8) were operated upon by one surgeon, using same approach. HSS improved from 33 to 75 post-operatively, the low figures reflecting a high percentage of Charnley C patients (71%). There was a 5% mortality rate from unrelated causes. Early complications included a 2.97% femoral fracture rate within 4–8 weeks of surgery (analysis showed no relation between implant position, BMI, age or Charnley classification, but there was correlation between high level of satisfaction and early weight bearing). There was one infection and one dislocation. Late complications included 3 periprosthetic fractures, 3 dislocations and 2 aseptic cup failures. However, 30% of patients developed groin pain, increasing stiffness and clunking at 1–2 years following surgery. These patients were investigated with an ultrasound scan. 28 patients (14%) had an effusion and were aspirated. Chrome and cobalt levels in synovial fluid, blood and urine were very high. 13 patients have been revised. 1 showed infection, 10 showed metal allergy and 2 a mixed picture of allergy and foreign body reaction. In our MOM database (762 hips including the current study) a total of 35 patients were revised for similar problems. Two distinct histological finding were observed. Metal allergy occurred independently of cup angle. The implants were well fixed; there was tissue necrosis and histological evidence of ALVAL. There was no infection or metalosis. FB reaction occurred more frequently when the cup was open. The Implants were loose; there was naked eye evidence of metalosis and metallic particles seen on light microscopy. We concluded that Birmingham/Freeman Hybrid had high complication rate without significant functional superiority, and other MoM devises shared similar complication. Both Metal allergy and FB reaction can occur in MOM THR. Ultra sound is a good screening tool in symptomatic patients

Introduction: Non union of the humerus in the ostoeportic bone is a great challenge for the orthopedic surgeon. The non weight bearing nature of this bone together with extreme osteoporosis seen in the elderly had rendered a high degree of failure in different modes of internal fixation of established humeral non union. Tantalum is a trabecullar metal with biomechanical properties similar to bone with a high modulus of elasticity and low rigidity. It is proved both in vitro and in vivo to induce excellent bone and vascular in growth and have been used successfully treating other application in orthopedics. We have introduced the tantalum rod for the treatment of humeral non union in the elderly. Patients and Methods: Six patients with humeral non-union were selected for tantalum rod implantations. All were above 60 years old. All patients had established non and 4 had failures after previous osteosynthesis. The surgical technique was exploration of the fracture site via a posterior or an anterolateral approach, debridement of the fracture site and intramedullary insertion of a 100 mm x 10 mm tantalum rod. No bone grafting was used. Ancillary fixation included a 4.5 broad DCP plate with screws drilled into both bone and rod or screws alone drilled into the bone and tantalum construct. Follow up period was up to one year. Results: All fractures united clinically and radiographicaly up to 3 months. All patients achieved satisfactory shoulder and elbow range of motion and regained functional activity. No infection or foreign body reaction was noted. Conclusion: Intramedullary tantalum rodding is a viable treatment option for the cases in both primary and secondary non union of the humeral shaft in osteoporotic bone

Surgibone (Unilab R) is a dry bone graft substitute prepared from Canadian bovine bone. It contains hydroxyapatite and 20–29% protein. The manufacturer claims that it is biocompatible; does not lead to foreign body reaction and does not produce pyrogenic effects. We have used Surgibone routinely in revision joint replacement surgery over a 6-year period, to augment autograft in filling osseous defects in the acetabulum and proximal femur. 27 patients who received Surgibone have been reviewed to assess the degree of graft incorporation, any evidence of graft rejection or immunogenic reaction. One patient died and 2 were excluded from the study for early fixation failure. The remaining 24 were studied 6 months to 5 years post surgery. In 17 patients (71%) there was radiological appearance of complete incorporation of the bone graft within 6 months. In 3 of these patients the graft incorporated as early as 3 months. There were 7 failures (29%). 3 patients have no radiological evidence of graft incorporation up to 3 years post surgery, although 2 have a satisfactory clinical result. Another 3 patients appeared to have graft rejection, and at revision were found to have sterile pus around the graft. These patients had negative responses to skin patch test for allergy to Surgibone. The seventh patient suffered an MRSA deep infection of the prosthesis that resulted in removal of the implants 4 weeks post operatively. We conclude that the use of xenograft Surgibone in revision hip surgery leads to unacceptable incidence of failure. Although in the majority of cases good incorporation of the graft was observed, there has been a substantial incidence of graft rejection

Methods: Sixty pseudo-capsular tissues from loose shoulder, hip and knee (20 each) arthroplasties and 30 capsular tissues from primary total joint arthroplasty (TJA) patients (10 each; 12 rheumatoid arthritis [RA], 18 osteo-arthrosis [OA]) were investigated for mRNA and protein expressions of IL-1ß (interleukin-1 b, IL-1Ra (interleukin-1 receptor antagonist), MMP 1 (matrix matalloproteinase-1)-, TIMP 2 (tissue inhibitor of MMPs-2) using in situ hybridisation and immunohistochemistry. Polyethylene and metal debris in the same sections were semi-quantified simultaneously. Results: IL-1ß mRNA and proteins were expressed in most RA primary and revision tissues and were less expressed in OA primary tissues. In contrast, IL-1Ra mRNA was found in most primary OA tissues and less in RA primary and the revision tissues. The ratio of staining intensities of IL-1ß/IL-1Ra mRNA was higher in revision and primary RA tissues compared with the primary OA tissues. MMP-1 protein expression was correlated with the IL-1ß/IL-1Ra ratio. Polyethylene (PE) debris was found in 56 out of 60 of the revision tissues. Their sizes were different in the hip (mainly small, < 30 mm in diameter), the knee (mainly large, > 300 mm) and the shoulder (all sizes). The expressions of the detected factors were highly correlated with the concentration of the PE debris but with not their sizes. Conclusions: The high ratio of IL-1ß/IL-1Ra in primary RA and revision tissues and its correlation with MMP-1 expression and PE debris concentration indicated that an over-expression of IL-1ß and/or regulation downwards of IL-1Ra is an important event in inflammatory disorders and the foreign body reaction in TJA. A therapeutic strategy with IL-1Ra, that has been considered in RA treatment may thus contribute to the longevity of prosthesis of a TJA

Among the wide variety of bone substitutes presently available, pure β-tricalcium phosphate ceramics have become available (Biosorb®; Aesculap, Tuttlingen). During the first 12 months of a prospective clinical trial, Biosorb® products were implanted in 21 patients. The ceramics were used in a variety of clinical settings, ranging from pelvic osteotomies in children (n=9), to filling of bone cysts or osseous defects (n=4), to dorsal spondylodesis (n=6), as well as for the grafting of pseudarthroses (n=2). Average follow-up period was 13 (6–18) months. The β-TCP granules, when used as part of a composite graft in combination with autologous bone, were completely resorbed after an average period of 14 weeks, while the cubes required 12 to 15 months. The more massive wedges have shown only a decrease in size and radio density. Due to the ability of the cubes and wedges to bear loads of up to 30 MPa, they were successfully implanted during pelvic osteotomies to augment or completely replace the bicortical grafts. Complications or foreign body reactions were not noted. The osseointegration was found to be favorable for all forms. In light of the problems associated with autologous and allogeneic grafts, the use of synthetic bone substitutes will continue to increase. The combination of complete resorption, lack of risk of infection, and load sharing ability make the β-tricalcium phosphate implants a valuable addition to the spectrum of bone replacement products presently available. Their use in pediatric orthopedics could help avoid donor site morbidity including contour changes or growth disturbances, while providing a more stable graft. During the first phase of a prospective clinical trial, we have come to the conclusion, that the β-tricalcium phosphate ceramics represent a real alternative to other bone substitutes

Summary Statement. To evaluate carbon-fiber-reinforced PEEK as alternative biomaterial for total disc arthroplasty a closed loop between biotribology (in vitro), application of sterile particle suspensions in the epidural space of rabbits and biological response in vivo was established. Introduction. To prevent adjacent level degeneration in the cervical spine, total disc arthroplasty (TDA-C) remains an interesting surgical procedure for degenerative disc disease. Short- or midterm complications are migration, impaired post-operative neurological assessment due to artefacts in x-ray and MRI diagnosis and substantial rates of heterotopic ossification. The idea was to create a TDA-C design based on a polymer-on-polymer articulation to overcome these limitations of the clinically established metal-on-polyethylene designs. The objective of our study was to characterise the biotribological behaviour of an experimental cervical disc replacement made out of carbon-fiber-reinforced (CFR) PEEK and evaluate the biological response of particulate wear debris in the epidural space in vivo. Materials & Methods. In vitro wear simulation acc. to ISO 18192-1 was performed for 10 million cycles on a clinically established TDA-C device (Aesculap, Tuttlingen) made of cobalt-chromium-on-polyethylene in a direct comparison to an experimental disc prototype made of CFR-PEEK. An estimation of particle size and morphology was done acc. to Affatato et al. [5] and sterile suspensions of comparable particles (size 90% < 1 µm) in phospate buffered saline (PBS) were produced [6] for the application in the epidural space of 36 white new zealand rabbits. The particle concentration was 1 mg/ml with a volume of 0.2 ml injected percutaneously using fluoroscopic guidance and the inflammatory response was assessed 3 and 6 months post-operatively in a direct comparison between the groups PBS (control), UHMWPE and CFR-PEEK. Results. The gravimetric wear rate was for the cobalt-chromium-on-polyethylene TDA-C device as a clinical reference 1.0 ± 0.1 mg/ million cycles, compared to 0.02 ± 0.02 mg/ million cycles for the experimental CFR-PEEK articulation (p < 0.001), whereas the cumulative amount of wear of the CFR-PEEK TDA-C prototypes (0.5 ± 0.23 mg/ million cycles) was decreased by an order of a magnitude compared to cobalt-chromium-on-polyethylene (12.1 ± 1.46 mg/ million cycles) (p < 0.001). For CFR-PEEK and UHMWPE most of the particles were observed in a submicron size range and the morphology was comparable. Histopathological examination demonstrated wear debris in the vertebral canal of injection sites surrounded by inflammatory cells. The inflammation was limited to the epidural space around the particles and polymer particles were associated by a low grade foreign body reaction comprising macrophages and multi-nucleated giant cells. CFR-PEEK particulate wear debris showed at least similar histopathological reactions than UHMWPE in the cervical epidural space. Conclusion. A closed loop between biotribology (in vitro), application of sterile particle suspensions in the epidural space of rabbits and biological response in vivo was established to evaluate carbon-fiber-reinforced PEEK as alternative biomaterial for total disc arthroplasty

Introduction and Objectives: The coating of implants with biomaterials seems to be a step further toward the ideal biological integration of an inert implant in live recipient bone where it will be subjected to load and movement. The goal of this study is to present results from 70 hip prostheses with implantation of a bioglass-coated stem. Materials and Methods: The “Grupo para el Estudio del Biovidrio” [Group for the Study of Bioglass] and the Stazione del Vetro de Murano experimented with a biocompatible, osteoconductive bioglass in 1992, creating the Biovetro patent as the first bioglass used for the coating of the CRM total hip prosthesis (Seipi-Bio-implant). In 1992, implantation of this prosthesis was begun in Italy and Spain. In 1994 and 1995, we implanted 70 TiAlva CRM stem total hip prostheses with the proximal two-thirds coated with an 80-micron thick layer of Biovetro. A Ceraver-Osteal impacted cup covered with a titanium mesh was used in all cases. Results: Of the 70 CRM prostheses implanted, adequate clinical and radiographic examination was possible in 62 cases, with an 8-year follow-up time. Clinical evaluation was done using the Merle D’Aubigne Postel criteria: pain, mobility, and gait. In 77% of patients, results were excellent or good, while 23% had fair or poor results. Radiographic evaluation according to Engh’s criteria for cementless stems showed 56 (90%) stable stems, 1 (1.6%) unstable stem, and 5 (8%) stem revisions, in one case due to infection. Survival rate for this stem at 8 years was 91.4%. Discussion and Conclusions: Based on these results, we believe Biovetro coating produces worse osteointegration than HA due to: 1) Appearance of a fibrous interface with a macrophage foreign body reaction. 2) Less new bone formation activity and a significant delay in maturation. 3) Insufficient mineralization of newly-formed bone

INTRODUCTION. The advantages of large diameter metal on metal total hip arthroplasty (MoM THA) and hip resurfacing arthroplasty are decreased wear rate, preservation of bone stock, anatomical restoration and enhanced stability. Large amounts of metal wear particles and metal ions are released which may induce adverse reactions including local soft tissue toxicity, hypersensitivity reactions, bone loss and risk of carcinogenesis. Aseptic loosening can be the result of a peri-prosthetic osteolysis generated as a result of a biological response to particulate wear debris. No reports in the literature exist as to whether circulating levels of Chromium (Cr) and Cobalt (Co) decrease upon removal of a symptomatic large diameter MoM implant or whether levels remain high due to the effect of metal ions debris left behind in the soft tissues after revision surgery. PATIENTS AND METHODS. Between June 2006 and June 2009 we undertook 44 revision surgeries of both large head MoM THAs (femoral head diameter 38mm) and metal-on-metal hip resurfacings for suspected metallosis. Mean time from original implant to revision was 4 years, 8 months (1yr 4mo–7yr 9mo). The mean follow up evaluation was 2 years and 2 months (1yr 2mo–4 years). Blood samples were taken for whole blood Cr and serum Co according to a recognised protocol and compared with reference levels indicated by the Medicines and Healthcare Regulatory Agency recommendation of less than 7ppb for Cr (130nM/L) and Co (119nM/L). RESULTS. 42 patients were found to have histological evidence of either metal allergy, metal toxicity or foreign body reaction. 2 patients had evidence of infection with no features of metal reaction. 3 patients suffered early dislocation requiring closed reduction. 1 patient had infective complications necessitating Girdlestones. 11 patients were lost to follow up, 8 patients were diagnosed pre operatively on Co and Cr levels in urine or synovial fluid aspirate alone. 23 patients had pre revision blood or serum metal ion level results available for direct comparison. Median serum Co level pre revision was 176.6nM/L, falling post revision to 5.1nM/L (p=<0.001∗). The median whole blood Cr level pre revision was 117nM/L and 19nm/L post revision (p=<0.001∗). Mean Oxford Hip Score was 23.7. DISCUSSION. This study demonstrates that at greater than one year post removal of a large diameter MoM hip implant for the indication of symptomatic metallosis or metal hypersensitivity, metal ion levels fall to almost normal levels and that outcome of revision surgery in terms of patient satisfaction is not adversely affected

Trabecular materials show great promise for soft-tissue attachment to prosthetic implants. Results with Tantalum have been very encouraging, however, it remains unclear if this in-growth is secondary to the specific metal or its generic structure,. If structure, is there a specific tolerance with respect to porosity and pore size? In a canine model, bulk blocks of porous alumina ceramic were shown to be completely ingrown by four weeks. The type material was not a factor, and effect of pore size revealed that there is a wide tolerance in facilitating in-growth with the larger pores having the greatest attachment strength (p=0.004). This study examines the in-vivo soft tissue in-growth potential of porous alumina ceramic and the effect of three distinct pore size ranges on this process. Alumina ceramic implants of fixed porosity (~ 85%) were designed in three pore size ranges (100–200, 250–400 and 600–800 μM). Using an established canine model, six implants (two of each type) were implanted in the dorsal subcutaneous tissues of tweleve mature canines and examined histologically and mechanically at four, eight and sixteen weeks with respect to type, amount and strength of soft tissue in-growth. Soft tissue in-growth was grossly evident in all implants at each time interval, and in each pore size. Microscopic examination revealed neo-vascularized in-growth throughout the implant, without evidence of inflammation or foreign body reaction. Numerous blood vessels were visible at the implant interface and within the porous alumina ceramic structure. With peel testing, the weakest attachment strength was with the small pore size with no differences between the medium and large pore sizes. An increase of attachment strength in each pore size was observed over time. This study suggests that architecture of porous structures in general, and not the type of material used, confers the biologic activity and that there is a wide tolerance for pore size in facilitating this process in soft tissue in-growth. Further study of other inert foam structures will be useful in further defining the assets and limitations of this genre of trabecular materials as a whole. Funding: Stryker Orthopaedics, Mahwah, NJ. Please contact author for figures, graphs, and/or diagrams

Aim: The purpose of this paper was to describe the biological reaction imposed by a prosthetic ligament. Materials-Methods: Polyester-carbon synthetic matrices were implanted into 29 rabbits. The implants were transected centrally and reconstructed with resorbable suture material. At regular intervals from 4th day to 29 weeks, tissue samples from the ingrown implants were obtained for histology and mechanical testing. Light microscopy, DNA cytometry, immunohistochemical analysis of the collagen types, transmission and scanning electron microscopy were carried out. Ultimate tensile strength (UTL), elongation to failure (EF) and structural stiffness (SS) were determined at intervals of 8, 16 and 29 weeks. Results: The ingrowth of tissue into the scaffold provided a significant increase in tensile strength, which improved with time. The UTL significantly increased from 18.86 N ±14.69 at 8 weeks to 51.4 N ±14.64 at 29 weeks. Light microscopy showed no infl ammation or foreign body reaction. At 4th day the first fibroblast cells settled on the matrix. The DNA cytometry showed an increase of the number of the fibroblast cell mitoses up to 16 days. After 2 weeks a mesh of connective tissue was formed around the scaffold, but the number of fibroblast cells remained constant. At 4 weeks the connective tissue started to infiltrate in between the artificial fibres. Type I, III and V collagens were identified. Electron microscopically the collagen weave was irregular with a mean fibril diameter of 28.4 ± 5.2 nm of a monophasic distribution. Collagen type I accumulated progressively and more and more dense collagenous fascicles appeared in the mesh in the proximity of the artificial fibres. Conclusion: The subcutaneous tissue may act as a bio-reactor and the skin fibroblast seeding of a synthetic matrix appears to be transformed a dense connective tissue during the first 4 weeks, providing tensile strength improvement to the tissue envelope with time

PURPOSE: Trapezial excision with ligament reconstruction combined with tendon interposition has proven to be a highly effective technique for the treatment of OA of the CMC joint. We believe the same procedure is possible with use of modern orthobiologics. Methods: 35 patients underwent surgical treatment for CMC arthritis with a new technique using Graft Jacket (Wright Med.) instead of FCR. Graft Jacket is an acellular human collagen (dermis) allograft. It is rapidly revascularized, repopulated with host cells and has high tensile strength. Technique: The Graft Jacket was rehydrated and cut to create a 15cm strip. It was then placed around or sutured to the FCR (the anchor) and passed into the intramedullary cavity of the metacarpal as in the standard LRTI procedure. The remaining Graft Jacket is sutured together as an anchovy to fill the former trapezium gap, so that both suspension and interposition occurred. The mean age of the patients was 56 years and the median follow-up period was 1 year. All patients had marked pain and radiographic evidence of severe arthritis before surgery. Pain, grip and pinch (tip and key) strength, stability and range of motion were measured pre- and post-operatively. Pain was assessed on a VAS (Visual Analog Scale). The ability to perform ADLs (Activities of Daily Living) requiring use of the thumb and to return to work were analyzed as well. Following surgery all thumbs were immobilized in a static splint for 10 days and then were placed into a removable orthoplast splint for 4–6 weeks. Radiographic examination was performed in all patients at the 10th post-op day, and also at 2 and 6 months after surgery. Results: Significants improvements were seen with grip strength (average 25lb) and tip (average 3.5lb) and key (average 4.5lb) pinch strength as well as palmar and radial abduction (average 25o). Pain was significantly reduced with an average of 6.0 on the VAS. There were no foreign body reactions or other infections in our series. Conclusions: This study showed that excellent results can be achieved in strength, pain reduction, range of motion and ADLs with this new technique in which Graft Jacket was utilized instead of FCR in ligament reconstruction and interposition arthroplasty of the CMC joint. Our results indicate less morbidity than with use of FCR (swelling, ecchymosis or weakness) with excellent final outcomes

In the Bunge repair strategy, a tube containing a Schwann cell cable bridges the cord lesion. Regenerating axons penetrate the proximal cord-graft interface and grow through the Schwann cell cable but the axons do not grow across distal cord-graft interface and into distal cord stump. Regeneration of axons can be promoted by applying neurotrophic factors in graft. Adding a matrix containing genes encoding for neurotrophic factors in the SC bridge between the proximal and distal cord-graft interfaces may promote axonal regeneration into the graft and the distal cord stump. Methods: There were 22 female fisher rats. One segment of 5-mm spinal cord was removed at T9 level. 6 of them (group1) received Schwann cell grafts positioned between transected stumps to test their efficacy to serve as bridges for axonal regeneration. 16 of them (group 2) received gene-treated Schwann cell grafts. All animals survived 4 weeks. Functional result was assessed by BBB behavior test everyweek after surgery. Fast-Blue injection into SC cable one week before perfusion. Immunocytochemistry to detect labeled neurons in cord, brain stem, and cortex. Toluidine blue stain for myelinated axons. Results: A bridge between the severed stumps had been formed in all animals, as determined by the gross and histological appearance and the ingrowth of propriospinal axons from both stumps. In group 1, near the bridge midpoint there was a mean of 1800 myelinated axons and eight times as many nonmyelinated, ensheathed axons. In group 2, more fibrous tissue surrounding grafted cords were noted. Myelinated axons can hardly find in group 2 animals excepted some unmyelinated axons. Histological examination shows vigorous inflammatory reaction with Macrophage dominant in the bridges. Conclusions: This study demonstrates that Schwann cell grafts serve as bridges that support regrowth of both ascending and descending axons across a gap in the adult rat spinal cord. The ground substance of gene-treated graft induced foreign body reaction that inhibits axon regeneration. Additional intervention will be required to eliminate this adverse reaction of the ground substance of gene-treated SC graft

Introduction Reported clinical results suggest that vertebroplasty is a safe and effective technique for providing pain relief. However, information about the long-term effect of PMMA on the adjacent intervertebral discs and the augmented bone is lacking. Adjacent intervertebral discs may be at higher risk of degeneration due to nutritional constraints. Bone loss in augmented vertebrae may occur due to mechanical stress-shielding or toxicological effects. The aim of the present study was therefore to investigate the effect of PMMA augmentation on intervertebral disc and bone tissue after 6 and 12 months, using an animal model. Methods In 12 skeletally mature sheep, 2.0ml PMMA (Simplex P) was injected into three lumbar vertebrae (approved by Animal Ethics Committee). Two injection holes were drilled into the middle of three vertebrae at a distance of 5.0mm from the cranial and caudal endplate and 1.0ml PMMA was injected into each hole. Four weeks before euthanasia, animals received an injection of tetracycline for bone labeling. Postmortem, T1- and T2-weighted sagittal and axial MR images were taken prior to fixation in 80% ethanol. Spines were cut into specimens containing one intervertebral disc and half of the two adjacent vertebrae. The discs which were two levels above the first augmented vertebra served as controls. Microsections were stained with H& E, Goldner, Alcian blue-PAS and Safranin O. MRI signal intensity and morphology of discs were evaluated qualitatively. Histomorphological analysis of discs and endplates was conducted using published criteria [. 1. ]. Presence of bone remodeling, fibrous tissue and foreign body reaction in the vertebrae was also recorded. Results There was no distinguishable loss of MRI signal intensity in the discs in between augmented vertebrae. Cement injection resulted in blocking 50–75% of the endplate lengths. Most discs that were in between augmented vertebrae showed signs of degeneration (chondrocyte proliferation, necrosis) after 6 (80%) and 12 months (88%). Inflammatory reaction to PMMA was observed in some specimens (approximately 25%). Cement had been covered with fibrous tissue in all augmented vertebrae, but tetracycline labeling revealed new bone formation in the vicinity of PMMA. Discussion Augmentation of three adjacent vertebrae initiated degenerative changes of intervertebral discs in between two augmented vertebrae. This is in contrast to previous animal studies [. 2. ] where no degenerative changes after cementing endplates were observed. Current investigations were performed with the specific aim to block the endplates. Clinically, endplates may not get blocked as effectively. On the other hand, discs in older patients are nutritionally constrained due to end-plate calcification and even partial blockage may lead to degenerative changes as documented presently. The risk of degenerative changes of intervertebral discs should be considered in patients undergoing vertebroplasty