Florian Amerstorfer

Long-term in vivo degradation behavior and near-implant distribution of resorbed elements for magnesium alloys WZ21 and ZX50

UNLABELLED We report on the long-term effects of degrading magnesium implants on bone tissue in a growing rat skeleton using continuous in vivo micro-Computed Tomography, histological staining and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Two different magnesium alloys-one rapidly degrading (ZX50) and one slowly degrading (WZ21)-were used to evaluate the bone response and distribution of released Mg and Y ions in the femur of male Sprague-Dawley rats. Regardless of whether the alloy degrades rapidly or slowly, we found that bone recovers restitutio ad integrum after complete degradation of the magnesium implant. The degradation of the Mg alloys generates a significant increase in Mg concentration in the cortical bone near the remaining implant parts, but the Mg accumulation disappears after the implant degrades completely. The degradation of the Y-containing alloy WZ21 leads to Y enrichment in adjacent bone tissues and in newly formed bone inside the medullary space. Locally high Y concentrations suggest migration not only of Y ions but also of Y-containing intermetallic particles. However, after the full degradation of the implant the Y-enrichment disappears almost completely. Hydrogen gas formation and ion release during implant degradation did not harm bone regeneration in our samples. STATEMENT OF SIGNIFICANCE Magnesium is generally considered to be one of the most attractive base materials for biodegradable implants, and many magnesium alloys have been optimized to adjust implant degradation. Delayed degradation, however, generates prolonged presence in the organism with the risk of foreign body reactions. While most studies so far have only ranged from several weeks up to 12months, the present study provides data for complete implant degradation and bone regeneration until 24months, for two magnesium alloys (ZX50, WZ21) with different degradation characteristics. μCT monitoring, histological staining and LA-ICP-MS illustrate the distribution of the elements in the neighboring bony tissues during implant degradation, and reveal in particular high concentrations of the rare-earth element Yttrium.

Elastic Stable Intramedullary Nailing (ESIN) of forearm fractures

ZusammenfassungOperationszielStabilisierung und Schienung von Unterarmfrakturen mittels intramedullär eingebrachter elastisch-stabiler Mark nägel (ESIN) und physiologischer Aufspannung des interossären Raums.IndikationenDiaphysäre Achsabweichungen > 10°.Frakturen mit Einengung des interossären Raums, da diese im Wachstum nicht ausgeglichen werden.KontraindikationenDistale metaphysäre Frakturen.Undislozierte instabile Frakturen, die keiner Reposition bedürfen.Offene Frakturen III. Grades.Stabile Grünholzfrakturen unterhalb des 5. Lebensjahrs.OperationstechnikAm Radius wird 2 cm proximal der distalen Epiphysenfuge radialseits inzidiert, und der Nagel wird vorsichtig aszendierend in das proximale Fragment eingebracht. Die Ulna wird deszendierend aufgefädelt. Zu diesem Zweck wird der Zugang unter Schonung der Olekranonapophyse etwa 2 cm distal der Apophysenfuge gewählt. Bei einer Grünholzfraktur am diaphysären Unterarm sollte die nicht durchgebrochene Kortikalis gebrochen werden. Zusätzlich werden die Marknägel für 6–8 Monate nach dem Trauma belassen, um die Refrakturrate zu verringern.WeiterbehandlungNach der Operation bedarf es keiner weiteren zusätzlichen Schienung, der Arm kann sofort entsprechend schmerzadaptiert belastet werden.Ergebnisse77 Kinder wurden operiert. Die durchschnittliche Operationsdauer betrug 44 min (10–140 min). Im Mittel blieben die Marknägel 7 Monate (1–13 Monate) in situ. Bei 74 Patienten (96%) wurden die postoperativen Komplikationen analysiert. Bei drei Patienten (4%) trat eine Wundinfektion an der Eintrittsstelle der Marknägel auf, und in einem Fall kam es zu einer Verbiegung der Marknägel nach erneutem Sturz auf den Unterarm. Ein Patient stürzte erneut auf den Arm und brach sich den distalen Radius mit den in situ befindlichen Marknägeln. Eine abschließende Untersuchung bei 70 Patienten zeigte lediglich in zwei Fällen (3%) ein minimales Funktionsdefizit.AbstractObjectiveFracture stabilization and restoration of bony anatomy with elastic stable intramedullary nailing (ESIN).IndicationsDiaphyseal forearm fractures with displacements > 10°.In cases of narrowing of the marrow cavity functional deficits can be encountered even in displacements < 10°.ContraindicationsDistal metaphyseal fractures.Undislocated unstable fractures with no need for repositioning.Grade III open fractures.Greenstick fractures in patients < 5 years.Surgical TechniqueAfter skin incision 2 cm proximal to the distal radial epiphysis, the cortical bone is transfixed diagonally toward proximal (ascending). The ulnar bone is transfixed from proximal to distal (descending). For that, a small incision 2 cm distal to the olecranon apophysis is made. To reduce the risk of refractures in case of greenstick fractures at the forearm, bones should be broken completely after introduction of the wires. Furthermore, implant removal is recommended approximately 6–8 months postoperatively.Postoperative ManagementNo additional fixation is required, allowing immediate functional treatment with early return to school.ResultsOperative treatment of forearm shaft fractures with ESIN was analyzed in 77 children. Average duration of surgery was 44 min (10–140 min). After an average of 7 months (1–13 months), the nails were removed. Postoperative complications were analyzed in 74 patients (96%). In three patients (4%), a superficial pin site infection emerged. One child (1%) fell on his arm again and broke his distal radius during ESIN treatment, and one patient (1%) showed deflected nails after a refall on the arm 1 week after surgery. Assessment of functional outcome in 70 patients revealed only two cases (3%) with minimal functional deficit.

Elastisch-stabile intramedulläre Marknagelung (ESIN) von Unterarmfrakturen

ZusammenfassungOperationszielStabilisierung und Schienung von Unterarmfrakturen mittels intramedullär eingebrachter elastisch-stabiler Mark nägel (ESIN) und physiologischer Aufspannung des interossären Raums.IndikationenDiaphysäre Achsabweichungen > 10°.Frakturen mit Einengung des interossären Raums, da diese im Wachstum nicht ausgeglichen werden.KontraindikationenDistale metaphysäre Frakturen.Undislozierte instabile Frakturen, die keiner Reposition bedürfen.Offene Frakturen III. Grades.Stabile Grünholzfrakturen unterhalb des 5. Lebensjahrs.OperationstechnikAm Radius wird 2 cm proximal der distalen Epiphysenfuge radialseits inzidiert, und der Nagel wird vorsichtig aszendierend in das proximale Fragment eingebracht. Die Ulna wird deszendierend aufgefädelt. Zu diesem Zweck wird der Zugang unter Schonung der Olekranonapophyse etwa 2 cm distal der Apophysenfuge gewählt. Bei einer Grünholzfraktur am diaphysären Unterarm sollte die nicht durchgebrochene Kortikalis gebrochen werden. Zusätzlich werden die Marknägel für 6–8 Monate nach dem Trauma belassen, um die Refrakturrate zu verringern.WeiterbehandlungNach der Operation bedarf es keiner weiteren zusätzlichen Schienung, der Arm kann sofort entsprechend schmerzadaptiert belastet werden.Ergebnisse77 Kinder wurden operiert. Die durchschnittliche Operationsdauer betrug 44 min (10–140 min). Im Mittel blieben die Marknägel 7 Monate (1–13 Monate) in situ. Bei 74 Patienten (96%) wurden die postoperativen Komplikationen analysiert. Bei drei Patienten (4%) trat eine Wundinfektion an der Eintrittsstelle der Marknägel auf, und in einem Fall kam es zu einer Verbiegung der Marknägel nach erneutem Sturz auf den Unterarm. Ein Patient stürzte erneut auf den Arm und brach sich den distalen Radius mit den in situ befindlichen Marknägeln. Eine abschließende Untersuchung bei 70 Patienten zeigte lediglich in zwei Fällen (3%) ein minimales Funktionsdefizit.AbstractObjectiveFracture stabilization and restoration of bony anatomy with elastic stable intramedullary nailing (ESIN).IndicationsDiaphyseal forearm fractures with displacements > 10°.In cases of narrowing of the marrow cavity functional deficits can be encountered even in displacements < 10°.ContraindicationsDistal metaphyseal fractures.Undislocated unstable fractures with no need for repositioning.Grade III open fractures.Greenstick fractures in patients < 5 years.Surgical TechniqueAfter skin incision 2 cm proximal to the distal radial epiphysis, the cortical bone is transfixed diagonally toward proximal (ascending). The ulnar bone is transfixed from proximal to distal (descending). For that, a small incision 2 cm distal to the olecranon apophysis is made. To reduce the risk of refractures in case of greenstick fractures at the forearm, bones should be broken completely after introduction of the wires. Furthermore, implant removal is recommended approximately 6–8 months postoperatively.Postoperative ManagementNo additional fixation is required, allowing immediate functional treatment with early return to school.ResultsOperative treatment of forearm shaft fractures with ESIN was analyzed in 77 children. Average duration of surgery was 44 min (10–140 min). After an average of 7 months (1–13 months), the nails were removed. Postoperative complications were analyzed in 74 patients (96%). In three patients (4%), a superficial pin site infection emerged. One child (1%) fell on his arm again and broke his distal radius during ESIN treatment, and one patient (1%) showed deflected nails after a refall on the arm 1 week after surgery. Assessment of functional outcome in 70 patients revealed only two cases (3%) with minimal functional deficit.

Superficial Vancomycin Coating of Bone Cement in Orthopedic Revision Surgery: A Safe Technique to Enhance Local Antibiotic Concentrations

BACKGROUND The use of antibiotic-loaded cement has become a well-accepted method to develop high local antibiotic concentrations in revision surgery of infected arthroplasty. A new surgical technique has been established to further increase the local antibiotic concentration and thereby minimizes the risk of reinfection. Our study aim was to investigate the safety of additional superficial vancomycin coating (SVC) by analyzing postoperative joint and serum vancomycin concentrations, as well as the creatinine levels of patients with orthopedic revision surgery. METHODS A longitudinal case series was performed by reviewing collected data of patients who were treated by SVC during revision surgery (1- or 2-stage exchange) because of prosthetic joint infections. Vancomycin levels were obtained, local from drains and systemic from blood samples, on postoperative days 1 to 5. Furthermore, preoperative and postoperative serum creatinine levels were analyzed. RESULTS Highest median local vancomycin levels were documented on postoperative day 1 with 546.8 μg/mL (range, 44.4-1485 μg/mL) in the reimplantation group and 408.7 μg/mL (range, 24.7-1650 μg/mL) in the spacer group. Median serum vancomycin level was 4.4 μg/mL (range, <2.0-11.7 μg/mL) on the first postoperative day in the reimplantation group and <2.0 μg/mL (range, <2.0-3.9 μg/mL) in the spacer group, and lower than 2.0 μg/mL (range, <2.0-7.5 μg/mL) from postoperative day 2 to 5 in both groups. Neither an anaphylactic reaction nor other side effects to SVC were observed. CONCLUSION Our data showed that SVC of bone cement is an effective technique to enhance local concentrations of vancomycin without leading to systemic side effects.

Pedicle screw loosening is correlated to chronic subclinical deep implant infection: a retrospective database analysis

PurposeSpinal fusion is used for treatment of spinal deformities, degeneration, infection, malignancy, and trauma. Reduction of motion enables osseous fusion and permanent stabilization of segments, compromised by loosening of the pedicle screws (PS). Deep implant infection, biomechanical, and chemical mechanisms are suspected reasons for loosening of PS. Study objective was to investigate the frequency and impact of deep implant infection on PS loosening.MethodsIntraoperative infection screening from wound and explanted material sonication was performed during revision surgeries following dorsal stabilization. Case history events and factors, which might promote implant infections, were included in this retrospective survey.Results110 cases of spinal metal explantation were included. In 29.1% of revision cases, infection screening identified a germ, most commonly Staphylococcus (53.1%) and Propionibacterium (40.6%) genus. Patients screened positive had a significant higher number of previous spinal operations and radiologic loosening of screws. Patients revised for adjacent segment failure had a significantly lower rate of positive infection screening than patients revised for directly implant associated reasons. Removal of implants that revealed positive screening effected significant pain relief.ConclusionsChronic implant infection seems to play a role in PS loosening and ongoing pain, causing revision surgery after spinal fusion. Screw loosening and multiple prior spinal operations should be suspicious for implant infection after spinal fusion when it comes to revision surgery.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.

Median Nerve Palsy following Elastic Stable Intramedullary Nailing of a Monteggia Fracture: An Unusual Case and Review of the Literature

Monteggia fractures are rare in children, and subtle radial head dislocations, with minor plastic deformation of the ulna, may be missed in up to a third of cases. Complications of Monteggia fractures-dislocations include persistent radial head dislocation, forearm deformity, elbow stiffness, and nerve palsies at the time of presentation. An unusual case of median nerve palsy following elastic stable intramedullary nailing of a type I Monteggia lesion in a 6-year-old girl is presented, and we highlight that, although most nerve palsies associated with a Monteggia fracture-dislocations are treated expectantly in children, early intervention here probably provided the best outcome.

Fibrinogen – A Practical and Cost Efficient Biomarker for Detecting Periprosthetic Joint Infection

The early and accurate diagnosis of periprosthetic joint infection (PJI) can be challenging. Fibrinogen plays an important role in mediating inflammation of bacterial infections and therefore could be a valuable biomarker for PJI. The purpose of this study was to investigate the sensitivity and specificity of serum levels of fibrinogen in detecting PJI, and to compare the results with the established PJI biomarkers C-reactive protein (CRP) and leukocyte count. Eighty-four patients (124 surgeries) were prospectively included. The preoperatively analyzed parameters were fibrinogen, CRP and leukocyte count. The sensitivity and specificity of the biomarkers were calculated and compared. Fibrinogen (p < 0.001), CRP (p < 0.001) and leukocyte count (p < 0.001) had a statistically significant correlation with the criteria defining the presence of PJI. For fibrinogen, the value of 519 mg/dl had a sensitivity of 0.90 and a specificity of 0.34. The CRP cut-off point of 11.00 mg/dl had a sensitivity of 0.90 and a specificity of 0.74. The leukocyte count of 5.68 G/l had a sensitivity of 0.90 and a specificity of 0.39. Our results indicated that fibrinogen is a significant biomarker for detecting a bacterial PJI. It has shown to be a cost-efficient diagnostic support with high sensitivity and specificity.

Septic Revision Total Knee Arthroplasty: Treatment of Metaphyseal Bone Defects Using Metaphyseal Sleeves

BACKGROUND Bone loss is a severe problem in septic revision total knee arthroplasty (RTKA). The use of porous coated metaphyseal sleeves is a promising treatment option for metaphyseal bone defects. The currently published midterm results remain limited and no study has been focused exclusively on septic cases. Our aim was to determine the implant survivorship (with special focus on osseointegration) and the clinical and radiological midterm outcome of metaphyseal sleeve fixation in septic RTKA surgery (minimum follow-up of 2 years). METHODS We performed a clinical and radiographic examination of 56 patients with a history of prosthetic joint infection who underwent 2-stage RTKA with the use of porous coated metaphyseal sleeves. These examinations included evaluation of the American Knee Society Score, the Western Ontario and McMaster Universities Osteoarthritis Index, the Short Form (SF-36) Health survey as well as radiographic measurement to determine whether successful osseointegration had been achieved. RESULTS Nine patients (16%) had to be re-revised at the time of follow-up (mean, 5.3 years; range, 2-11.2), all due to reinfection. We did not encounter any cases of aseptic loosening. The mean range of motion (92°, SD ± 21°), subjective satisfaction score (7, SD ± 2), American Knee Society Score (76, SD ± 19), Western Ontario and McMaster Universities Osteoarthritis Index (70, SD ± 20), SF-36 mental component summary (55, SD ± 14), and SF-36 physical component summary (35, SD ± 9) have shown satisfying results. CONCLUSION Metaphyseal sleeves have shown very promising midterm results regarding clinical scores, osseointegration, and aseptic loosening. Our results are the first analyzing exclusively septic indications and indicate that they are a reliable fixation option in all bone defect types in septic RTKA patients.

Einfluss chronischer Implantat Infektion auf Pedikelschrauben-Lockerung nach Spondylodese

Fragestellung: Spondylodese der Wirbelsaule ist eine chirurgische Technik, welche zur Behandlung von spinalen Deformitaten, Degenerationen, Infektionen, Tumoren und Traumata angewandt wird. Die dadurch erreichte Bewegungseinschrankung fuhrt zur permanenten ossaren Fusion der[zum vollstandigen Text gelangen Sie uber die oben angegebene URL]

Elastisch-stabile intramedulläre Marknagelung (ESIN) von Unterarmfrakturen@@@Elastic Stable Intramedullary Nailing (ESIN) of Forearm Fractures

ZusammenfassungOperationszielStabilisierung und Schienung von Unterarmfrakturen mittels intramedullär eingebrachter elastisch-stabiler Mark nägel (ESIN) und physiologischer Aufspannung des interossären Raums.IndikationenDiaphysäre Achsabweichungen > 10°.Frakturen mit Einengung des interossären Raums, da diese im Wachstum nicht ausgeglichen werden.KontraindikationenDistale metaphysäre Frakturen.Undislozierte instabile Frakturen, die keiner Reposition bedürfen.Offene Frakturen III. Grades.Stabile Grünholzfrakturen unterhalb des 5. Lebensjahrs.OperationstechnikAm Radius wird 2 cm proximal der distalen Epiphysenfuge radialseits inzidiert, und der Nagel wird vorsichtig aszendierend in das proximale Fragment eingebracht. Die Ulna wird deszendierend aufgefädelt. Zu diesem Zweck wird der Zugang unter Schonung der Olekranonapophyse etwa 2 cm distal der Apophysenfuge gewählt. Bei einer Grünholzfraktur am diaphysären Unterarm sollte die nicht durchgebrochene Kortikalis gebrochen werden. Zusätzlich werden die Marknägel für 6–8 Monate nach dem Trauma belassen, um die Refrakturrate zu verringern.WeiterbehandlungNach der Operation bedarf es keiner weiteren zusätzlichen Schienung, der Arm kann sofort entsprechend schmerzadaptiert belastet werden.Ergebnisse77 Kinder wurden operiert. Die durchschnittliche Operationsdauer betrug 44 min (10–140 min). Im Mittel blieben die Marknägel 7 Monate (1–13 Monate) in situ. Bei 74 Patienten (96%) wurden die postoperativen Komplikationen analysiert. Bei drei Patienten (4%) trat eine Wundinfektion an der Eintrittsstelle der Marknägel auf, und in einem Fall kam es zu einer Verbiegung der Marknägel nach erneutem Sturz auf den Unterarm. Ein Patient stürzte erneut auf den Arm und brach sich den distalen Radius mit den in situ befindlichen Marknägeln. Eine abschließende Untersuchung bei 70 Patienten zeigte lediglich in zwei Fällen (3%) ein minimales Funktionsdefizit.AbstractObjectiveFracture stabilization and restoration of bony anatomy with elastic stable intramedullary nailing (ESIN).IndicationsDiaphyseal forearm fractures with displacements > 10°.In cases of narrowing of the marrow cavity functional deficits can be encountered even in displacements < 10°.ContraindicationsDistal metaphyseal fractures.Undislocated unstable fractures with no need for repositioning.Grade III open fractures.Greenstick fractures in patients < 5 years.Surgical TechniqueAfter skin incision 2 cm proximal to the distal radial epiphysis, the cortical bone is transfixed diagonally toward proximal (ascending). The ulnar bone is transfixed from proximal to distal (descending). For that, a small incision 2 cm distal to the olecranon apophysis is made. To reduce the risk of refractures in case of greenstick fractures at the forearm, bones should be broken completely after introduction of the wires. Furthermore, implant removal is recommended approximately 6–8 months postoperatively.Postoperative ManagementNo additional fixation is required, allowing immediate functional treatment with early return to school.ResultsOperative treatment of forearm shaft fractures with ESIN was analyzed in 77 children. Average duration of surgery was 44 min (10–140 min). After an average of 7 months (1–13 months), the nails were removed. Postoperative complications were analyzed in 74 patients (96%). In three patients (4%), a superficial pin site infection emerged. One child (1%) fell on his arm again and broke his distal radius during ESIN treatment, and one patient (1%) showed deflected nails after a refall on the arm 1 week after surgery. Assessment of functional outcome in 70 patients revealed only two cases (3%) with minimal functional deficit.