by G. H. | Jun 24, 2019 | Hüfte + Endoprothetik, Knie + Endoprothetik, News
Correlation between low corrosion resistance and osteosarcoma
Sprecher CM, Boudrieau RJ, Suter T, Keating JH, McCarthy RJ, Gueorguiev B, Richards G, Milz S
Objective: Peri-implant osteosarcoma (OSA) occurrence was found in dogs treated with the Slocum cast stainless steel tibial plateau leveling osteotomy (TPLO) plate. Recently, it was assumed that the metallurgical inhomogeneity of the plate surface, or the reduced corrosion resistance of the cast stainless steel material, were related to OSA occurrence. Therefore, the aim of the current study was to investigate the corrosion behavior of TPLO plate surfaces from animals with and without OSA.
Method: Eighteen retrieved 316L cast stainless steel Slocum TPLO plates, 9 from dogs with (CwOS) and 9 from dogs without peri-implant osteosarcoma (CnOS) were investigated. Three retrieved forged stainless steel TPLO plates (Synthes) from dogs without osteosarcoma (FnOS) represented a different manufacturing process. On all plates, visual inspections with a stereomicroscope and local micro electrochemical corrosion measurements were performed on plastic deformed surface areas in 1M NaCl on various spots (d=0.1mm) and corrosion resistance factors (CRF) were calculated. To assess the metallurgical inhomogeneity, nine randomly positioned corrosion measurements were performed on one plate of each group. The Mann-Whitney U Test was used for statistical analysis.
Results and conclusion: The time in-situ was comparable for both cast implant groups (CwOS 59±19 months vs. CnOS 52±14 months) and was shorter for FnOS (35±5 months). Microscopic inspections on the cast groups showed rough surfaces, residues and signs of local corrosion attacks. Furthermore, local notches and more severe tool marks were found next to the contoured regions of the plate. On the forged plates only few marks, but no residues or microscopic signs of corrosion could be detected. The CRF values determined on different surface spots showed a wide variation for the cast plates and a small bandwidth in forged plates; the differences between groups were significant (p<0.001). Repeated measurements on one plate of each group showed a significantly higher ion production for CwOS than for CnOS (p=0.008) or FnOS (p<0.001).
The local micro electrochemical corrosion measurements showed no clear difference between local corrosion behaviors of the two groups of cast plates due to a large standard deviation. The ion measurements clearly show a significant increase of ion release for the OSA group, which resembles the metallurgical inhomogeneity of the plate surface. Both corrosion and metal ion release result in chronic inflammation in the tissues with oncogenic effects; furthermore, direct toxic effects of these ions may also contribute to a foreign-body carcinogenesis. Despite our findings and their implications, there remains no clear evidence for a direct causal connection between the surface properties of cast plates, the local CRF and the occurrence of peri-implant OSA. Nevertheless, our results add to the speculation that OSA development might be related to local surface corrosion and the influence of that condition on neighboring bone cells.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocGR21-757
doi: 10.3205/14dkou556, urn:nbn:de:0183-14dkou5565
Published: October 13, 2014
© 2014 Sprecher et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
by R-Dorotka | Apr 3, 2019 | Chirurgische Orthopädie, Konservative Orthopädie, News
Intracellular proliferation of S. aureus in osteoblasts and effects of rifampicin and gentamicin on S. aureus intracellular proliferation and survival
Mohamed W, Sommer U, Domann E, Schnettler R, Alt V
Objective: Staphylococcus aureus is the most frequent causal agent for bone infection. When S. aureus infection affects a total joint arthroplasty, removal and replacement of joint is mostly required. Moreover, it was recently discovered that S. aureus is able to invade osteoblasts thus escaping the extracellular host antibacterial defense and even antibiotics. This plays a significant role in persistence and recurrence of infection. The aim of this study was to investigate whether (1) S. aureus is able to not only invade but also proliferate within osteoblasts, (2) the mechanism of invasion and (3) to clarify whether rifampicin or gentamicin can inhibit intracellular proliferation and survival of S. aureus.
Method: SAOS-2 osteoblast-like cell line were grown in Minimum Essential Medium and subsequently infected with S. aureus EDCC5055 and S. aureus Rosenbach 1884 (ATCC 12598). In order to test the mode of bacterial internalization, SAOS-2 cells were treated 2h prior to infection with cytochalasin D which is the major actin depolymerization agent disrupting actin microfilaments. Immunofluorescence and transmission electromicroscopic (TEM) imaging were performed to detect potential intracellular and proliferating bacteria. For antibiotic experiments, SAOS-2 osteoblasts infected with S. aureus were treated with 7.5 microgram/ml of rifampicin or 30 microgram/ml, 100 microgram/ml, or 200 microgram/ml of gentamicin for 4h and 24h.
Results and conclusion: Both S. aureus strains were able to efficiently invade and to proliferate within human osteoblasts shown by typical bacterial growth curves. Immunofluorescence microscopy showed intracellular invasion of S. aureus and TEM images could demonstrate bacterial division as well as disruption of lysosomal membranes as a sign of successful intracellular proliferation and survival. Cytochalasin D was able to significantly reduce S. aureus invasion ability suggesting that invasion was enabled by promoting actin rearrangement at the cell surface. 7.5 microgram/ml of rifampicin was able to inhibit bacterial survival in human osteoblasts with almost complete elimination of bacteria after 4 h. Effects of gentamicin were dose-dependent but even high doses with 200 microgram/ml of gentamicin were associated with a statistically significant higher number of survived bacteria compared to rifampicin. In conclusion, S. aureus is not only able to invade but also to proliferate in osteoblasts. Invasion seems to be associated with actin rearrangement at the cell surface. Rifampicin is effective in intracellular eradication of S. aureus whereas gentamicin seems to have a much weaker intracellular effect. Based on these data, doses of rifampicin and gentamicin could be optimized for local use to coat end prostheses and be able to reach the intracellular compartments thus killing the probable intracellular persisting S. aureus without causing undesirable systemic side effects.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocGR17-1222
doi: 10.3205/14dkou524, urn:nbn:de:0183-14dkou5245
Published: October 13, 2014
© 2014 Mohamed et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
by G. H. | Nov 26, 2018 | Arthrosetherapie, News
ROBUST-Regeneration of osteoporotic bone using stem cell transplantation
Saxer F, Studer P, Miot S, Todorov A, Schaefer D, Martin I, Scherberich A, Jakob M
Fragestellung: Ist die Nutzung nicht-expandierter undifferenzierter Zellen der stromal vaskulären Fraktion (SVF) des menschlichen Fettgewebes als zelluläre Komponente eines Composite-Grafts zur biologisch aktiven Augmentation von Knochendefekten und Frakturen im Tiermodell bzw. der Klinik möglich?
Methodik: SVF Zellen wurden aus dem Fett menschlicher Spender nach Enzymverdau anhand des Dichtegradienten isoliert. Sie wurden mittels Fibrin Gel auf Hydroxyapatit-Träger (Actifuse, Baxter, USA) aufgebracht und in Femurdefekte kritischer Grösse athymer Ratten (Crl:NIH-Foxn1mu, Charles River, Deutschland) implantiert, die mittels RatFix System (RISystem AG, Schweiz) stabilisiert wurde. Nach 8 Wochen in vivo wurden die Femora entnommen und histologisch, sowie biomechanisch untersucht. Im Rahmen einer Sicherheits- und Machbarkeitsstudie erfolgte die Translation des Ansatzes. Patienten mit Indikation zur offenen Reposition und Osteosynthese einer osteoporotischen proximalen Humerusfraktur wurden bei entsprechender Einwilligung und Eignung ca. 300 ml Fett per Liposuction entnommen. Aus dem Aspirat wurde im Cellution800/CRS (Cytori, USA) die SVF isoliert und nach o.g. Prinzip zur Zellularisierung eines Grafts genutzt, mit dem die Fraktur augmentiert wurde. Protokolldeviationen und Komplikationen wurden dokumentiert. Im Fall einer Implantatentfernung wurde eine Biopsie entnommen. Die implantierten Zellen wurden im Tiermodell und der klinischen Studie anhand ihrer Oberflächenmarker und Klonogenität charakterisiert.
Ergebnisse und Schlussfolgerung: Im Tiermodell konnte in 2/3 der Behandlungsgruppe das Auftreten von Knochen und Gefässen humanen Ursprungs nachgewiesen werden. In 1/3 der Fälle wurde eine Torsionsstabilität ähnlich der physiologischer Rattenfemora nachgewiesen. Nach Implantation zellfreier Grafts traten instabile Pseudarthrosen ohne histologischen Knochennachweis auf. 6 Patienten wurden bisher in die klinische Studie eingeschlossen. Grobe Protokoll-Deviationen oder prozesstechnische Schwierigkeiten gab es nicht. Die Patienten tolerierten den Zusatzeingriff gut. Durchschnittlich wurden 137 Mio Zellen (32-220 Mio) implantiert. Bei 3 Patienten kam es zu relevanten Komplikationen, die nicht auf die Implantation des Grafts zurückzuführen waren. In zwei bereits entnommenen Biopsien nach 6 bzw. 32 Wochen fand sich Osteoid bzw. Knochen im Graft. Die isolierten Zellen zeigten eine durchschnittliche Klonogenität um 10% mit osteogenem Potenzial in 1/3. 60% exprimierten mesenchymale Marker, 10% endotheliale, deren Proportionen jedoch ohne erkennbaren Einfluss auf das klinische Ergebnis waren.
Dieser einzeitige Ansatz zur Herstellung eines osteo- und vaskulogen aktiven Grafts ist in der klinischen Anwendung sicher und machbar. Er umgeht die Morbidität eines autologen Knochengrafts, sowie bei Osteoporose die Dysfunktionalität der darin enthaltenen Stammzellen. Zudem fördert er die Vaskularisierung des Gewebes. Insgesamt handelt es sich insofern um eine vielversprechende Technik, deren Effektivität zu beweisen wäre.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocGR13-481
doi: 10.3205/14dkou482, urn:nbn:de:0183-14dkou4821
Published: October 13, 2014
© 2014 Saxer et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
by G. H. | Sep 3, 2018 | Knie + Endoprothetik, News
Finite element simulation of locking compression plates for femur fracture treatment under different boundary conditions
Jalali J, König B, Wittkowske C, Nolte A, Eder M, Raith S, Volf A, Kovacs L
Objective: The incidence of femoral shaft fractures is reported as being 1 per 10,000 people. This rate increases to 3 per 10,000 people in male individuals younger than 25 years and elderly patients, above the age of 65 years. The locking compression plate (LCP) is a common tool in the treatment of femoral shaft fractures. In osteoporotic patients, stable fixation of the plate can be a challenge since the bone often lacks the desired stability. This may lead to a high complication rate due to the loosening of screws or breakage of the implant.
Method: Finite element simulation is a powerful method to predict the effects of varying parameters which cannot be easily varied in a laboratory environment. In this project, which is funded by BMWi, an automated workflow was developed to support surgeons in their decision of the appropriate implant dimensions and where to place the screws in order to achieve an optimal fracture healing and to prevent implant failure after a femoral shaft fracture. This workflow has been used for the simulation of a non-osteoporotic 22-year old female and a 68-year old male with osteoporotic bone. A virtual transverse femoral shaft fracture with a gap of 3 mm was created using the software Blender (Blender Foundation). The exact geometry of a distal femur LCP was provided by Synthes (Synthes GmbH) as triangulated surface data.
CT data were imported into the software Mimics (Materialise) and used for patient specific modeling of the inhomogeneous material properties of bone. Hounsfield Units (HU) were exported and assigned to elements of a finite element mesh. HU of bone were correlated with mechanical properties such as the Young’s modulus. A linear finite element analysis was performed with ANSYS Classic (Ansys Inc.).
Results and conclusion: The boundary conditions are one of the most important parameters influencing the outcome a of finite element simulation. Three different loading situations which all model the physiological loading following surgery were compared.
- Force application from distal
- Force application from proximal
- Forces derived from a muscoskeletal model using the software AnyBody (AnyBody Technology A/S)
With this workflow monocortical and bicortical screw fixations were compared in variable positions to determine biomechanical effects. The optimal screws position in terms of interfragmentary movement was validated among different variations.
This workflow has also the potential to be used in other anatomical regions.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocWI60-1328
doi: 10.3205/14dkou441 , urn:nbn:de:0183-14dkou4411
Published: October 13, 2014
© 2014 Jalali et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
by G. H. | Sep 4, 2017 | Knie + Endoprothetik, News
Effect of medial opening wedge high tibial osteotomy on intraarticular knee and ankle contact surface pressures
Suero EM, Hawi N, Sabbagh Y, Westphal R, Wahl FM, Krettek C, Citak M, Liodakis E
Objective: High tibial osteotomy (HTO) is a commonly used surgical technique for treating moderate osteoarthritis (OA) of the medial compartment of the knee by shifting the center of force towards the lateral compartment. Previous studies have documented the effects of HTO on the biomechanics of the knee. However, the effects of the procedure on the contact pressures within the ankle joint have not been well described.
Methods: A medial, L-shaped opening wedge high tibial osteotomy was performed on eight cadaveric lower leg specimens. A previously developed stainless-steel device with integrated load cell was used to axially load the leg. Pressure-sensitive sensors were used to measure intraarticular contact pressures. Intraoperative changes in alignment were monitored in real time using computer navigation. Baseline measurements were taken for each leg in its native alignment. An axial loading force was applied to the leg in the caudal-craneal direction and gradually ramped up from 0 to 550 N. Intraarticular contact pressure (kg) and contact area (mm2) data were collected.
Multiple linear regression models were constructed to estimate changes in contact pressure and contact surface area in the medial and lateral compartments of the knee and in the ankle, in response to 5º, 10º and 15º changes in mechanical alignment.
Results and conclusion: Small changes in mechanical alignment (5º) resulted in a nonsignificant 11.7% increase in lateral compartment contact pressures compared to the intact leg (P>0.05). However, larger changes in alignment correction resulted in a 76.4% increase in contact pressures at 10º and a 152.9% increase at 15º (P<0.05). In the medial compartment, a 27.1% increase in pressure at 5º was followed by a 21.3% decrease at 10º and a 49.4% decrease at 15º. These changes were not statistically significant (P >0.05).
The intraarticular surface contact area did not significantly change in the lateral compartment (P>0.05). In the medial compartment, a 5º change in alignment resulted in a 9.4% increase in contact area (P<0.05). A change in alignment of 10º resulted in a 6.2% decrease in contact area (P>0.05), while a 15º change in alignment resulted in a significant 28.1% decrease in contact area (P<0.05). A 5º change in mechanical alignment did not significantly alter intraarticular ankle pressures (P>0.05). However, larger corrections decreased contact pressures by 27.0% at 10º (P<0.05) and by 23.6% at 15º (P>0.05).
Significant reductions in contact area were observed after each step of alignment correction: 12.3% at 5º (P<0.05); 21.6% at 10º (P<0.05); and 26.5% at 15º (P<0.05).
We conclude that small valgus realignment of the proximal tibia does not significantly alter the biomechanics of the ankle. However, moderate-to-large changes in proximal tibial alignment result in significantly decreased tibiotalar contact surface area and in changes in intraarticular ankle pressures.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocWI43-625
doi: 10.3205/14dkou288, urn:nbn:de:0183-14dkou2889
Published: October 13, 2014
© 2014 Suero et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
