IL-7 receptor signaling drives human B-cell progenitor differentiation and expansion

Although absence of interleukin-7 (IL-7) signaling completely abrogates T and B lymphopoiesis in mice, patients with severe combined immunodeficiency caused by mutations in the IL-7 receptor α chain (IL-7Rα) still generate peripheral blood B cells. Consequently, human B lymphopoiesis has been thought to be independent of IL-7 signaling. Using flow cytometric analysis and single-cell RNA sequencing of bone marrow samples from healthy controls and patients who are IL-7Rα deficient, in combination with in vitro modeling of human B-cell differentiation, we demonstrate that IL-7R signaling plays a crucial role in human B lymphopoiesis. IL-7 drives proliferation and expansion of early B-cell progenitors but not of pre-BII large cells and has a limited role in the prevention of cell death. Furthermore, IL-7 guides cell fate decisions by enhancing the expression of BACH2, EBF1, and PAX5, which jointly orchestrate the specification and commitment of early B-cell progenitors. In line with this observation, early B-cell progenitors of patients with IL-7Rα deficiency still expressed myeloid-specific genes. Collectively, our results unveil a previously unknown role for IL-7 signaling in promoting the B-lymphoid fate and expanding early human B-cell progenitors while defining important differences between mice and humans. Our results have implications for hematopoietic stem cell transplantation strategies in patients with T- B+ severe combined immunodeficiency and provide insights into the role of IL-7R signaling in leukemogenesis.

POS0400 MODULATION OF HUMAN EARLY B CELL DEVELOPMENT THROUGH TARGETED DEGRADATION OF IKAROS AND AIOLOS WITH IBERDOMIDE

Background

B differentiation in the bone marrow (BM) is impaired in patients carrying mutation in the IKFZ1 gene, coding for Ikaros a zinc-finger transcription factor. High Ikaros expression is on the contrary associated with systemic lupus erythematosus[1] and multiple myeloma[2]. Targeted treatment with iberdomide, a cereblon modulator which enhances degradation of Ikaros and Aiolos, is under clinical investigation in multiple myeloma patients and systemic lupus erythematosus. However, consequences of the treatment on human early B cell development remain elusive. Immature B cells develop in the BM from hematopoietic stem cells. An intricate network of transcription factors regulates the maturation process. Ikaros and Aiolos regulate gene expression during B cell development. As reported in mice, Ikaros is essential for the commitment to the lymphoid lineage and later, together with Aiolos, ensures the transition from pre-BII large to pre-BII small cells.

Objectives

Investigate the effect of iberdomide (CC-220) on human early B cell development simulated in vitro.

Methods

We tested the impact of iberdomide on short term culture of BM-derived lymphocytes and in a unique in vitro modeling of early B cell development starting from cord blood (CB)- CD34+ progenitors [3, 4]. We used multi-dimensional spectra flow cytometry (17-color pan-el) to dissect early B cell subpopulations.

Results

Iberdomide treatment led to enhanced degradation of Ikaros and Aiolos in both BM- and CB-derived cultures. Addition of iberdomide early (day 7) to the CB-derived culture impaired the specification to the lymphoid lineage and later also the commitment to the B cell lineage. These observations were confirmed by reduced E2A and PAX5 gene expression, respectively. Treatment with iberdomide on B cell precursors (pro- and pre-B cells, day 28 of culture) on one side it enhanced the proliferation of early progenitors resulting in increased amount of CD10+CD38+ lymphoid-committed cells. On the other side, it resulted in a accumulation of pre-B cells and inefficient development of immature B cells.

Conclusion

Iberdomide impairs the commitment to the lymphoid lineage by enhancing Ikaros’ degrada-tion. When targeting already committed B cells, iberdomide treatment undermines the transition of pre-BII large to pre-BII small cells due to increased Aiolos’ degradation, conse-quently impairing the development of immature B cells. Our data can instruct immunologi-cal monitoring of patients treated with iberdomide, and provide insights in the mechanisms of therapeutic efficacy.

References

[1]Rivellese, F., et al., Effects of targeting the transcription factors Ikaros and Aiolos on B cell activation and differentiation in systemic lupus erythematosus. Lupus Sci Med, 2021. 8(1).

[2]Thakurta, A., et al., Developing next generation immunomodulatory drugs and their combinations in multiple myeloma. Oncotarget, 2021. 12(15): p. 1555-1563.

[3]Kraus, H., et al., A Feeder-Free Differentiation System Identifies Autonomously Proliferating B Cell Precursors in Human Bone Marrow. The Journal of Immunology, 2014. 192(3): p. 1044-1054.

[4]Troilo, A., et al., Nonpermissive bone marrow environment impairs early B-cell development in common variable immunodeficiency. Blood, 2020. 135(17): p. 1452-1457.

Disclosure of Interests

Iga Janowska: None declared, Jakov Korzhenevich: None declared, Julian Staniek: None declared, Raquel Lorenzetti: None declared, Lukas Konstantinidis: None declared, Miriam Erlacher: None declared, Peter Schafer Employee of: BMS, Reinhard Voll: None declared, Jens Thiel Grant/research support from: BMS (former Cellgene), Nils Venhoff: None declared, Marta Rizzi Grant/research support from: BMS (former Cellgene)

10-year follow-up of the Columbus knee prostheses system in a prospective multicenter study

INTRODUCTION

As endpoint of a prospective multicenter 10-year documentation using the Columbus system, this evaluation carried out results of clinical scores (Knee Society Score and Oxford Knee Score), an evaluation of radiological imaging, survival rates and a collection of complication statistics.

MATERIALS AND METHODS

There was a multicenter prospective recruitment of consecutive patients with the indication for total knee replacement (TKR). Preoperatively and 10 years after implantation, clinical scores, range of motion and radiological imaging was performed. During this period, a detailed documentation of complications was made.

RESULTS

A total of 210 patients were recruited in 5 centers. 140 patients were available for endpoint examination 10 years after surgery. A survival rate of 96.6% (CI 95%) for the implanted Columbus prostheses after 10 years was demonstrated. Cumulative KSS showed an improvement of 75.3 (± 38.1) points and was highly significant (p < 0.0001, t test). The average functional improvement in the Oxford score was 20.6 (± 9.5) points and was also highly significant (p < 0.0001). The ROM improved from 106.5° (± 20.5) preoperatively to 116.0° (± 11.5) (p < 0.0001, t test). There were no implant-related complications as well as no new complication documented between 5- and 10-year follow-up.

CONCLUSIONS

The endpoint analysis after an observation period of 10 years provided good clinical and radiographic results. In particular, an excellent survival rate of 96.6% after 10 years was demonstrated. The data published in this study are the first to be available in a prospective multicenter study on this system, which leads to a high level of clinical significance.

Characteristics of patients with complete visual acuity recovery after vitrectomy for macula-off retinal detachment

PURPOSE

The purpose of this study is to investigate potential factors predicting complete recovery of visual acuity following surgery for macula off retinal detachment (RD).

PATIENTS AND METHODS

Retrospective review of patients operated for macula-off RD at Jules-Gonin Eye Hospital between January 2015 and December 2016. The study included patients with visual acuity recovery of 0 LogMAR. A control group of 83 patients with comparable baseline characteristics but partial recovery of visual acuity after vitrectomy for macula-off RD was used for statistical comparison analysis.

RESULTS

Seventy-four patients, 46 males (62%) and 28 females (38%), were included. Mean age was 65 years (standard deviation: 12). Median follow-up was 6 months (interquartile range: 3). Fifty patients (68%) were pseudophakic. Median pre-op best-corrected visual acuity (BCVA) was 2 LogMAR (interquartile range: 1.22). Forty-three of the patients (58%) had preoperative BCVA equivalent of count fingers or less. The majority of the patients (91%) had up to 3-day duration of macular detachment (MD) before surgery. In comparison only 18% of the group of patients with partial recovery of visual acuity after vitrectomy for macula-off RD had been operated within 3 days of MD (p < 0.0001). In 63% of the 40 cases in whom an optical coherence tomography (OCT) of the fovea could be interpreted, OCT image showed a retained foveal depression of the detached retina, whereas only 35% of the 46 control eyes with adequate OCT imaging showed a retained foveal depression (p = 0.01).

CONCLUSIONS

In our study, patients had significantly better chances of complete visual acuity recovery when operated within 3 days of MD in comparison to more delayed surgery. Additionally, preservation of the foveal depression of the detached retina appeared to be a common characteristic among patients demonstrating complete visual recovery.

Inhibition of the anti-apoptotic protein MCL-1 severely suppresses human hematopoiesis

BH3-mimetics inhibiting anti-apoptotic BCL-2 proteins represent a novel and promising class of antitumor drugs. While the BCL-2 inhibitor venetoclax is already approved by the Food and Drug Administration, BCL-XL and MCL-1 inhibitors are currently in early clinical trials. To predict side effects of therapeutic MCL-1 inhibition on the human hematopoietic system, we used RNA interference and the small molecule inhibitor S63845 on cord blood-derived CD34⁺ cells. Both approaches resulted in almost complete depletion of human hematopoietic stem and progenitor cells. As a consequence, maturation into the different hematopoietic lineages was severely restricted and CD34⁺ cells expressing MCL-1 shRNA showed a very limited engraftment potential upon xenotransplantation. In contrast, mature blood cells survived normally in the absence of MCL-1. Combined inhibition of MCL-1 and BCL-XL resulted in synergistic effects with relevant loss of colony-forming hematopoietic stem and progenitor cells already at inhibitor concentrations of 0.1 mM each, indicating “synthetic lethality” of the two BH3- mimetics in the hematopoietic system.

Biomechanical dynamic comparison of biodegradable pins and titanium screws for operative stabilization of displaced radial head fractures

For radial head osteosynthesis, biodegradable implants are gaining in importance to minimize cartilage destruction and implant impingement and to supersede implant removal. Since loss of reduction and pseudarthrosis remain challenging complications, new implants should at least provide comparable biomechanical properties as commonly used metal implants. The objective of this study was to compare the treatment by polylactide pins to titanium screws and to quantify the produced cartilage defects. Eight pairs of human cadaver radii with a standardized Mason type II fracture were stabilized either by two 2.0-mm polylactide pins or titanium screws. The produced cartilage defects were quantified using an image analyzing software. Quasi-static loading was performed axially and transversally for 10 cycles each between 10 and 50 N. Afterward, implant loosening was tested by axial loading up to 10,000 cycles, followed by load to failure testing. Polylactide pins showed less construct stiffness under axial (p = 0.017) and transversal (p = 0.012) loading, and one polylactide pins construct failed after two cycles of transversal loading. At axial loading, a high correlation between bone mineral density and construct stiffness was observed among polylactide pins (R = 0.667; p = 0.071), which was not seen among titanium screws (R = 0.262; p = 0.531). No difference in implant loosening was recorded after 10,000 cycles (p = 0.237); however, one polylactide pins construct failed after 30 cycles and failure loads were higher for titanium screws (p=0.017). Polylactide pin produced smaller cartilage defects (p=0.012). In conclusion, simple radial head fractures treated by polylactide pins show less biomechanical stability than treated by titanium screws, particularly in osteoporotic bone which might lead to secondary loss of reduction. Due to smaller cartilage defects and equal properties under continuous loading, polylactide pins might represent a gentle alternative in patients with good bone quality making subsequent implant removal redundant.

Diagnose Arthrose

Die Arthrose ist eine multifaktorielle Erkrankung, die pathoanatomisch durch den vollständigen Verlust des Gelenkknorpels gekennzeichnet ist.

Epidemiologie und Prognose Die Erkrankung weist einen klaren Altersbezug auf, und betrifft 20% der Bevölkerung über 60 Jahre. Am häufigsten sind die Gelenke der Hand betroffen, danach folgen die großen Körpergelenke der unteren Extremität. Über einen 10 Jahreszeitraum kommt es bei einem Drittel bis zu der Hälfte der Patienten zur Progression der Erkrankung.

Einflußfaktoren Biomechanik, Sport und Körpergewicht Anlagestörungen wie Achsabweichungen der Beine oder auch mechanische Engpassyndrome des Hüftgelenkes sind biomechanische Risikofaktoren. Ein erhöhtes Körpergewicht stellt den größten Risikofaktor für die Entwicklung einer Gonarthrose dar. Sport auf internationalem Wettkampfniveau oder körperliche Arbeit dem regelmäßigen Tragen schwerer körperlicher Lasten sind weitere Risikofaktoren für die Entwicklung einer Arthrose.

Klinische Diagnose und Bildgebung und Lebensqualität Die Patienten weisen Ruhe- und Belastungsschmerzen, sowie Bewegungseinschränkungen auf. Der klinische Goldstandard ist die belastete Röntgenaufnahme in 2 Ebenen. Für die Frühdiagnose der Arthrose werden MRT Untersuchungen benötigt. Arthrosepatienten weisen eine verminderte Lebensqualität mit Beeinträchtigung der mentalen Gesundheit auf.

Pathophysiologie Anteil an der Arthroseentstehung und deren Progression haben zunächst der Gelenkknorpel und der subchondrale Knochen, die Synovia und die das Gelenk umgebende Muskulatur. Die biologischen Prozesse im Knorpel führen zu einer enzymatisch vermittelten Degradation von Typ II Kollagen und den Proteoglycanen. Über die Synovialis werden proinflammatorische Zytokine in das Gelenk und den Organismus sezerniert, worunter die Chondrozyten eine Hypertrophie und Apoptose entwickeln. Eine Verminderung der gelenkführendem Muskulatur steht am Beginn und nicht am Ende der Arthroseentwicklung. Die benannten Risikofaktoren (Achse und Gelenkmechanik, sowie sportliche oder arbeitstägliche Belastung) bewirken bei Überschreiten der Gelenkhomöostase den Beginn der Arthroseentwicklung. Ein metabolisches Syndrom wirkt sich über das erhöhte Körpergewicht, zusätzlich durch eine systemische Entzündungskonstellation verstärkend auf die Arthroseentwicklung aus. Das vermehrt vorhandene Fettgewebe wirkt bei den Patienten mit metabolischem Syndrom als endokrines Organ und sezerniert Zytokine, die als Adipokine bezeichnet werden.

Genetik und Epigenetik Mittels Genom-weiter Assoziationsstudien werden Zusammenhänge zwischen der individuellen genetischen Ausstattung und der Arthroseentwicklung hergestellt. Aus der Zwillingsforschung ist die unterschiedliche Erkrankungswahrscheinlichkeit für Hüft- und Kniegelenk bei gleicher genetischer Ausstattung gezeigt worden. Die Epigenetik beschäftigt sich mit dem Zusammenspiel zwischen der genetischen Information und den molekularen Mechanismen, die zu einer unterschiedlichen Ausprägung führen. Einfluss darauf haben das Erbgut selbst, Umwelteinflüsse und stochastische Zufälle. Der wichtigste bisher beschriebene Mechanismus ist die DNA-Methylierung. Mit bevölkerungsbasierten Kollektiven sind anhand von einfachen Merkmalen Kellgren-Lawrence Score des Gelenkes, der Quadricepskraft, des Körpergewichtes und der Depressivität unterschiedliche Phänotypen der Arthrose beschrieben worden. Künftig wird eine stärker individualisierte Therapie in Hinblick auf den Phänotyp erwartet.

[5-year follow-up of 210 Columbus knee prostheses : A prospective multicentre study]

INTRODUCTION

As part of 10-year documentation using the Columbus system, the interim evaluation was carried out 5 years after implantation with a collection of clinical scores, evaluation of radiological imaging and collection of statistics concerning complications.

METHODS

There was a multicentre prospective recruitment of consecutive patients with the indication of implantation of a surface replacement prosthesis (Columbus CR, Deep Dish fixed inlay). Preoperatively, clinical scores were recorded (KSS and Oxford score). Five years postoperatively a new evaluation of clinical scores, the range of motion (ROM) and a radiological check-up including full leg imaging under load was performed. During this period, detailed complication documentation was made.

RESULTS

A total of 210 patients were recruited in five centres. 187 patients were available for examination 5 years after surgery. Cumulative KSS increased from 87.5 (±26.6) preoperatively to 170 (±29.1) 5 years postoperatively. The cumulative KSS improvement was 81.5 (±35.2) points and was highly significant (p < 0.0001; t‑test). The average functional improvement in the Oxford score between the preoperative and 5‑year follow-up was 21.7 (±8.8) points and was also highly significant (p < 0.0001). The ROM improved from 106.3° (±20.2) preoperatively to 114.0° (±12.1) 5 years postoperatively (p < 0.0001; t test). Five years after implantation, the average mechanical leg axis was 178.0° (±2.1). There was no clinically apparent or native radiologic visible aseptic loosening of the femoral or tibial joint component. There were 33 complications, but no implant-related complications such as inlay dislocation, material fracture or aseptic loosening. In total, 6 revision surgeries were performed during the follow-up period, which corresponds to a survival rate of 97.1% (CI 95%) for the implanted Columbus knee in the present patient collective for 5 years.

CONCLUSION

The interim analysis at 5 years of long-term observation of the Columbus system provided good clinical and radiographic results.

Identifying Disparities in the Management of Hip Fractures Within Europe: A Comparison of 3 Health-Care Systems

Introduction:

This study investigates the management of hip fractures in a German maximum care hospital and compares these data to evidence-based standard and practice in 180 hospitals participating in the UK National Hip Fracture Database (NHFD) and 16 hospitals participating in the Irish Hip Fracture Database (IHFD). This is the first study directly comparing the management of hip fractures between 3 separate health-care systems within Europe.

Methods:

Electronic medical data were collected retrospectively describing the care pathway of elderly patients with a hip fracture admitted to a large trauma unit in the south of Germany “University Hospital Freiburg” (UHF). The audit evaluated demographics, postoperative outcome, and the adherence to the 6 “Blue Book” standards of care. These data were directly compared with the data from the UK NHFD and the IHFD acquired from 180 and 16 hospitals, respectively.

Results:

At 36 hours, 95.8% of patients had received surgery in UHF, compared to 71.5% in the NHFD and 58% of patients in the IHFD. The rate of in-hospital mortality was 4.7% compared to 7.1% in the NHFD and 5% in the IHFD. The mean average acute length of stay was 13.4 days compared to 16.4 days in the NHFD and 20 days in the IHFD. Reoperation rates are 3.3% compared to 1% in the NHFD and 1.1% in the IHFD; 50.5% of patients were discharged on bone protection medication, compared to 47% in the IHFD and 79.3% in the UK NHFD.

Discussion:

Despite uniformly acknowledged evidence-based treatment guidelines, the management of hip fractures remains heterogeneous within Europe.

Conclusion:

These data show that different areas of the hip fracture care pathway in Germany, England, and Ireland, respectively, show room for improvement in light of the growing socioeconomic burden these countries are expected to face.

Biomechanical in vitro evaluation of a ready-to-use calcium phosphate cement implanted to augment intramedullary nail fixation of a three-part humeral head fracture model

The aim of this study was the dynamic biomechanical evaluation of a ready-to-use oil-based calcium phosphate cement paste implanted to augment intramedullary nail fixation of a three-part humeral head fracture model. Fractures in the osteoporotic bone are often fractures of the proximal humerus. Secondary fracture displacements due to cut-out in osteoporotic bone have been observed in up to 13% of cases. Procedures have been developed to augment fracture fixation with polymethylmethacrylate to increase stability, but there are still unsolved challenges relating to its material-specific properties. Calcium phosphate cement could be a biological alternative in the augmentation of osteoporotic fractures because of its more favourable material properties. Fracture fixation was performed on eight pairs of human cadaveric bones to stabilize a standardized three-part humeral head fracture model by implantation of the Targon^® PH (Braun-Aesculap AG, Tuttlingen, Germany) intramedullary nail and insertion of three head screws and two bicortical shaft screws. The procedure was randomized, and one bone of each pair received calcium phosphate cement augmentation. Custom-made cannulated screws with an open lateral slot facilitated augmentation, making it possible to cement the threaded portion of the screw (1-mL calcium phosphate cement/screw). After the calcium phosphate cement had hardened, the humeri were subjected to dynamic axial loading. Load was progressively increased, monitored by ultrasound-based motion analysis, and total deformation was recorded. Load testing continued until implant failure. The augmented group withstood significantly more cycles before implant failure. The average initial stiffness showed a significant difference between the two study groups. Ultrasonic sensor technology was used to measure angular displacement during testing and a significant difference was found. Calcium phosphate cement offers a potential alternative to implant augmentation in the treatment of osteoporotic humeral head fractures. Future studies are required to confirm these observations clinically in vivo.

Histopathological effects of modern topical sealants on the liver surface after hepatectomy: an experimental swine study

The present study aimed to determine the impact of different sealant materials on histopathological changes to the liver surface after liver resection. Thirty-six landrace pigs underwent left anatomical hemihepatectomy and were assigned to a histopathological control group (HPC, n = 9) with no bleeding control, a clinically simulated control group (CSC, n = 9) with no sealant but bipolar cauterization and oversewing of the liver surface, and two treatment groups (n = 9 each) with a collagen-based sealant (CBS) or a fibrinogen-based sealant (FBS) on resection surface. After postoperative day 6, tissue samples were histologically examined. There were no significant differences in preoperative parameters between the groups. Fibrin production was higher in sealant groups compared with the HPC and CSC groups (both p < 0.001). Hepatocellular regeneration in sealant groups was higher than in both control groups. A significantly higher regeneration was seen in the FBS group. Use of sealants increased the degree of fibrin exudation at the resection plane. Increased hepatocellular necrosis was seen in the CBS group compared with the FBS group. The posthepatectomy hepatocellular regeneration rate was higher in the FBS group compared with the CBS group. Randomized studies are needed to assess the impact of sealants on posthepatectomy liver regeneration in the clinical setting.

In vitro modeling of human B cell development can identify distinct physiopathological patterns in primary antibody deficiency (PAD)

Bone marrow (BM) analysis show that 20% of PAD patients harbor a block at an early stage of B cell development. The aim of this work is to study the mechanisms of this developmental block. We set up a feeder free cultivation system that in healthy donors leads to the development of lymphocyte progenitors until the stage of Immature B cells.

BM derived CD34+ cells are expanded in cytokine cocktail for 2 weeks. From day 14 to day 49 cells are cultivated in cytokine-free medium and analyzed once a week by flow cytometry and RNA is collected for PCR assays.

BM derived CD34+ cells from 15 PAD patients and 2 Btk-deficient patients were tested in vitro for their capability to develop into IgM+ Immature B cells. CD34+ cells from patients showing a normal B cell development in vivo (6/17) developed in vitro until the stage of Immature B cells. Among PAD patients presenting a block at early B cell stage, 5/11, including the Btk-deficient patients, could not reach the Immature B cell stage, while 6/11 could develop in vitro until the stage of IgM+ B cells. Among this last group, reaching Immature B cell stage in vitro but not in vivo, 2/6 patients showed a rapid in vitro development of Immature B cells at day 14, but presented a progressive exhaustion of the common lymphoid progenitors (CLP) compartment. In patients with a block in B cell development (in vivo and in vitro), PCR analysis revealed adelayed expression of transcription factors E2A, CD79a and PAX5, reflecting an impaired lineage commitment.

Combining BM phenotyping and in vitro modeling we identified four patients’ groups characterized by (1) an intrinsic B cell defect, (2) a defect in the BM microenvironment impairing early stages of B cell development, (3) a defect in repopulation of CLP and (4) normal B cell development.

Evaluation of hemodynamic goal-directed therapy to reduce the incidence of bone cement implantation syndrome in patients undergoing cemented hip arthroplasty - a randomized parallel-arm trial

BACKGROUND

The bone cement implantation syndrome (BCIS) is a frequent and potentially disastrous intraoperative complication in patients undergoing cemented hip arthroplasty. Several risk factors have been identified, however randomized controlled trials to reduce the incidence of BCIS are still pending. We hypothesized that goal-directed hemodynamic therapy guided by esophageal Doppler monitoring (EDM) may reduce the incidence of BCIS in a randomized, controlled parallel-arm trial.

METHODS

After approval of the local ethics committee, 90 patients scheduled for cemented hip arthroplasty at the Medical Center - University of Freiburg were randomly assigned to either standard hemodynamic management or goal-directed therapy (GDT) guided by an esophageal Doppler monitoring-based algorithm. The primary endpoint was the incidence of overall BCIS including grade 1-3 after cementation of the femoral stem. Secondary endpoints included cardiac function, length of hospital stay and postoperative complications.

RESULTS

Ninety patients were finally analyzed. With regards to the primary endpoint, the overall incidence of BCIS showed no difference between the GDT and control group. Compared to the control group, patients of the GDT group showed a higher cardiac index before and after bone cement implantation (2.7 vs. 2.2 [l●min^- 1●m^- 2]; 2.8 vs. 2.4 [l●min^- 1●m^- 2]; P = 0.003, P = 0.042), whereas intraoperative amount of fluids and mean arterial pressure did not differ.

CONCLUSIONS

The implementation of a specific hemodynamic goal-directed therapy did not reduce the overall incidence of BCIS in patients undergoing cemented hip arthroplasty.

TRIAL REGISTRATION

This randomized clinical two-arm parallel study was approved by the local Ethics Committee, Freiburg, Germany [EK 160/15, PI: U. Goebel] and registered in the German Clinical Trials Register ( DRKS No. 00008778 , 16th of June, 2015).

Analysis of the hemostatic potential of modern topical sealants on arterial and venous anastomoses: an experimental porcine study

One of the widely accepted adjunctive agents in the variety of surgical modalities are sealants. Our study aim was to compare four commonly used modern sealants in a standardized experimental setting to assess their feasibility, and hemostatic efficacy in vascular anastomosis. Forty landrace pigs (weight: 24.7 ± 3.8 kg) were randomized into the control (n = 8) and four sealant groups; TachoSil® (n = 8), Tissucol Duo® (n = 8), Coseal® (n = 8), and FloSeal® (n = 8). After doing a portal vein end-to-end anastomosis as well as stitches of aortic incision, the sealants were applied on anastomotic site. The control group was left intact. In portal vein anastomosis, the sealants led to a complete hemostasis significantly better than control group. The mean of blood loss was also significantly reduced. In successful subgroups, there was a difference in the mean-time to reach complete hemostasis ranging from 15 s in Coseal® to 76 s in FloSeal® group (p  < 0.05). In aortotomy experiments, except Tissucol Due®, which had insufficient hemostasis, other sealants led to a complete hemostasis. The mean blood loss was significantly reduced in sealants groups as well. The four sealants are effective in reducing the suture-hole bleeding in portal vein anastomosis. However, the hemostatic potential is heterogeneous among sealants. This means that "one-size-fits-all" approach is not appropriate for application of sealants in diversity of vascular surgery and it should be based on the type and the severity of injury and the structure of tissue. Comparison of hemostasis efficacy of four modern sealants (TachoSil®, Tissucol Duo®, Coseal®, and FloSeal®) in vascular anastomosis in porcine model. The figures below show the total blood loss (g) in the control and sealant groups after aortotomy (left) and portal vein anastomosis (right). The mean of blood loss decreased significantly by the usage of sealants in both experiment groups as compared to control group (*: p < 0.05; sealant groups vs. control group). 1. The right column shows the mean of blood loss (g) in all experiments in each group. 2. The middle column presents the subgroup with unsuccessful hemostasis at the end of observation time (Tmax = 20 sec. for aortotmy and 300 sec. for portal vein anastomosis). 3. The left column shows mean of total blood loss in subgroups with successful hemostasis during observation time (20 sec for aortotomy and 300 sec for portal vein).

Patellar tendinopathy in young elite soccer- clinical and sonographical analysis of a German elite soccer academy

Background

The prevalence of patellar tendinopathy is elevated in elite soccer compared to less explosive sports. While the burden of training hours and load is comparably high in youth elite players (age < 23 years), little is known about the prevalence of patellar tendinopathy at this age. There is only little data available on the influence of age, the amount of training, the position on the field, as well as muscular strength, range of motion, or sonographical findings in this age group. The purpose of the present study was to examine the above-mentioned parameters in all age groups of a German youth elite soccer academy.

Methods

One hundred nineteen male youth soccer players (age 15,97 ± 2,24 years, height 174, 60 ± 10,16 cm, BMI 21, 24 ± 2,65) of the U-13 to U-23 teams were part of the study. Data acquisition included sport specific parameters such as footwear, amount of training hours, leg dominance, history of tendon pathologies, and clinical examination for palpatory pain, indurations, muscular circumference, and range of motion.

Subjective complaints were measured with the Victorian Institute of Sport Assessment Patellar (VISA-P) Score. Furthermore, sonographical examinations (Aplio SSA-770A/80; Toshiba, Tokyo, Japan) with 12-MHz multifrequency linear transducers (8–14 MHz) of both patellar tendons were performed with special emphasis on hyper- and hypo echogenic areas, diameter and neovascularization.

Results

The prevalence of patellar tendinopathies was 13.4%. Seventy-five percent of the players complained of pain of their dominant leg with onset of pain at training in 87.5%. The injured players showed a medium amount of 10.34 ± 3.85 training hours and a medium duration of symptoms of 11.94 ± 18.75 weeks. Two thirds of players with patellar tendinopathy were at the age of 15–17 (Odds ratio 1.89) while no differences between players of the national or regional league were observed.

In case of patellar tendinopathy, VISA-P was significantly lower in comparison to healthy players (mean ± SD 76.80 ± 28.56 points vs. 95.85 ± 10.37). The clinical examination revealed local pain at the distal patella, pain at stretching, and thickening of the patellar tendon (p = 0.02).

The mean tendon diameter measured 2 cm distally to the patella was 4.10 ± 0.68 mm with a significantly increased diameter of 0.15 mm in case of an underlying tendinopathy (p = 0.00). The incidence of hypo-echogenic areas and neovascularizations was significantly elevated in players with patellar tendon syndrome (PTS) (p = 0.05).

Conclusion

The prevalence of patellar tendinopathy in youth elite soccer is relatively high in comparison to available data of adult players. Especially players at the age of 15 to 17 are at considerable risk. Tendon thickening, hypo-echogenic areas, and neovascularization are more common in tendons affected by PTS.

[Prosthetic Joint Infection after Total Hip Arthroplasty: Results of an Online Questionnaire about Current Diagnostic and Therapeutic Procedures in 107 German Hospitals]

Background Prosthetic hip joint infection is a common severe complication with a high socio-economic impact. The inconsistency of the available data and the absence of binding guidelines lead to a variety of diagnostic and therapeutic strategies. The aim of this study is to present the current diagnostic and therapeutic approach to treating infections after total hip arthroplasties in German hospitals, link it with current evidence, and evaluate the willingness of these hospitals to participate in prospective multicentre trials. Material and Methods An online questionnaire for digital processing was sent to hospitals performing joint replacement procedures. These institutions included district hospitals, private hospitals, non-university maximum care facilities, statutory accident insurance hospitals, and university hospitals. Results A total of 107 hospitals took part in the survey, corresponding to a response rate of 27.6%. These hospitals perform approximately 2,951 revisions of infected total hip arthroplasties per year. Two-stage revision arthroplasty is the preferred procedure after prosthetic hip infections. The algorithm proposed by Zimmerli et al. is widely recognised. There is a lack of uniformity in the key features for revision of prosthetic joint infections - long vs. short interval in case of two-stage revision, duration of intravenous and oral administration of antibiotics, cemented vs. cement-free implant procedures, and follow-up intervals after revision surgery. The willingness to participate in clinical trials is high. Conclusion The controversial data leads to multiple treatment approaches. The high willingness to participate in adequately funded clinical trials offers a potential for multicentre trials to be conducted. There is an urgent need for funding to make this research possible.

Analysis of the biliostatic potential of two sealants in a standardized porcine model of liver resection

BACKGROUND

Improved resection techniques has decreased mortality rate following liver resections(LRx). Sealants are known as effective adjuncts for haemostasis after LRx. We compared biliostatic effectiveness of two sealants in a standardized porcine model of LRx.

MATERIAL AND METHODS

We accomplished left hemihepatectomy on 27 pigs. The animals were randomized in control group(n = 9) with no sealant and treatment groups (each n = 9), in which resection surfaces were covered with TachoSil^® and TissuFleece^®/Tissucol Duo^®. After 5 days the volume of ascites(ml), bilioma and/or bile leakages and degree of intra-abdominal adhesions were analysed.

RESULTS

Proportion of ascites was lower in TissuFleece/Tissucol Duo^® group. The ascites volume was lower in TachoSil^® group. In sealant groups, increased adhesion specially in the TachoSil^® group was seen. A reduction of the "bilioma rate" was seen in sealant groups, which was significantly lower in TissuFleece^®/Tissucol Duo^® group.

CONCLUSION

In a standardized condition sealants have a good biliostatic effect but with heterogeneous potentials. This property in combination with the cost-benefit analysis should be the focus of future prospective studies.

The effect of sclerotherapy and prolotherapy on chronic painful Achilles tendinopathy-a systematic review including meta-analysis

Chronic painful Achilles tendinopathy (AT) is a common disorder among athletes. Sclerotherapy (ST) and prolotherapy (PT) are two promising options among the numerous other conservative therapies. As their efficacy and potential adverse effects (AE) are still unclear, we systematically searched, analyzed, and synthesized the available literature on ST and PT for treating AT. Electronic databases, Google Scholar and articles' reference lists were searched according to PRISMA guidelines. Eligibility criteria were set up according to the PICOS-scheme including human and animal studies. Three authors independently reviewed the results and evaluated methodological quality (Coleman Methodology Score and Cochrane Risk of Bias Assessment). The initial search yielded 1104 entries. After screening, 18 articles were available for qualitative synthesis, six of which were subjected to meta-analysis. The mean Coleman Score of the 13 human studies was 50. Four RCTs were ranked as having a low risk of selection bias. Three of those reported a statistically significant drop in the visual analog scale (VAS) score, one a significant increase in the VISA-A Score. 12 of 13 human studies reported positive results in achieving pain relief and patient satisfaction, whereas only one study's finding differed. Meta-analysis revealed an unambiguous result in favor of the intervention (weighted mean difference D=-4.67 cm, 95% CI -5.56 to -3.76 cm [P<.001]). Only one serious AE and two minor AEs were reported in the entire literature. This systematic review suggests that ST and PT may be effective treatment options for AT and that they can be considered safe. Long-term studies and RCTs are still needed to support their recommendation.

Quadriceps Strength in Patients With Isolated Cartilage Defects of the Knee: Results of Isokinetic Strength Measurements and Their Correlation With Clinical and Functional Results

Background:

Recent studies have found a significant deficit of maximum quadriceps strength after autologous chondrocyte implantation (ACI) of the knee. However, it is unclear whether muscular strength deficits in patients with cartilage damage exist prior to operative treatment.

Purpose:

To isokinetically test maximum quadriceps muscle strength and quantify the impact of possible strength deficits on functional and clinical test results.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

To identify clinically relevant muscular strength deficits, 24 patients (5 females, 19 males; mean age, 34.5 years; body mass index, 25.9 kg/m²) with isolated cartilage defects (mean onset, 5.05 years; SD, 7.8 years) in the knee joint underwent isokinetic strength measurements. Maximal quadriceps strength was recorded in 3 different testing modes: pure concentric contraction (flexors and extensors alternating work; con1), concentric-eccentric (only the extensors work concentrically and eccentrically; con2), and eccentric contraction in the alternating mode (ecc). Results were compared for functional performance (single-leg hop test), pain scales (visual analog scale [VAS], numeric rating scale [NRS]), self-reported questionnaires (International Knee Documentation Committee [IKDC], Knee Injury and Osteoarthritis Outcome Scale [KOOS]), and defect size (cm²).

Results:

Compared with the uninjured leg, significantly lower quadriceps strength was detected in the injured leg in all isokinetic working modes (con1 difference, 27.76 N·m [SD 17.47; P = .003]; con2 difference, 21.45 N·m [SD, 18.45; P =.025]; ecc difference, 29.48 N·m [SD, 21.51; P = .001]), with the largest deficits found for eccentric muscle performance. Moderate negative correlations were observed for the subjective pain scales NRS and VAS. The results of the IKDC and KOOS questionnaires showed low, nonsignificant correlations with findings in the isokinetic measurement. Moreover, defect sizes (mean, 3.13 cm²) were of no importance regarding the prediction of the strength deficit. The quadriceps strength deficit between the injured and the uninjured leg was best predicted by the results of the single-leg hop test.

Conclusion:

Patients with isolated cartilage defects of the knee joint have significant deficits in quadriceps muscle strength of the injured leg compared with the uninjured leg. The single-leg hop test may be used to predict quadriceps strength deficits. Future research should address whether preoperative strength training in patients with cartilage defects of the knee could be effective and should be taken into consideration in addition to surgical treatment.

Operative versus conservative treatment of apophyseal avulsion fractures of the pelvis in the adolescents: a systematical review with meta-analysis of clinical outcome and return to sports

Background

Avulsion fractures of the pelvic apophyses typically occur in adolescent athletes due to a sudden strong muscle contraction while growth plates are still open. The main goals of this systematic review with meta-analysis were to summarize the evidence on clinical outcome and determine the rate of return to sports after conservative versus operative treatment of avulsion fractures of the pelvis.

Methods

A systematic search of the Ovid database was performed in December 2016 to identify all published articles reporting outcome and return to preinjury sport-level after conservative or operative treatment of avulsion fractures of the pelvis in adolescent patients. Included studies were abstracted regarding study characteristics, patient demographics and outcome measures. The methodological quality of the studies was assessed with the Coleman Methodology Score (CMS).

Results

Fourteen studies with a total of 596 patients met the inclusion criteria. The mean patient age was 14.3 ± 0.6 years and 75.5% of patients were male. Affected were the anterior inferior iliac spine (33.2%), ischial tuberosity (29.7%), anterior superior iliac spine (27.9%), iliac crest (6.7%) lesser trochanter (1.8%) and superior corner of the pubic symphysis (1.2%). Mean follow-up was 12.4 ± 11.7 months and most of the patients underwent a conservative treatment (89.6%). The overall success rate was higher in the patients receiving surgery (88%) compared to the patients receiving conservative treatment (79%) (p = 0,09). The rate of return to sports was 80% in conservative and 92% in operative treated patients (p = 0,03). Overall, the methodological quality of the included studies was low, with a mean CMS of 41.2.

Conclusion

On the basis of the present meta-analysis, the overall success and return to sports rate was higher in the patients receiving surgery. Especially in patients with fragment displacement greater 15 mm and high functional demands, surgical treatment should be considered.

Plate fixation of periprosthetic femur fractures: What happens to the cement mantle?

Osteosynthesis of periprosthetic femur fractures by screw fixation around the implanted prosthetic stem is currently regarded as the biomechanically superior option compared with cerclage. The aim of this biomechanical study was damage analysis of the cement mantle after revision screw insertion. A prosthetic stem (Bicontact) was implanted in 20 cadaveric femora in cemented technique. A locking compression plate (Synthes) was then applied to the lateral femur at the level of the prosthetic stem. The method of plate fixation to the femur was assigned randomly to three groups: bicortical non-locking screws, monocortical locking screws, and bicortical locking screws. This was followed by applying a fluctuating axial load (2100 N, 0.5 Hz) for 20,000 cycles. After testing, macroscopic and microscopic evaluations of the cement mantle were conducted. Cracks formed in the cement mantle in 14% of the 80 screw holes. The type of screw (bicortical or monocortical; locking or non-locking) had no significant effect on the number of cracks (p = 0.52). The relationship between manifestation of crack damage and cement mantle thickness was not significant (p = 0.36), whereas the relationship between crack formation and screw position was significant (p = 0.019). Those screws whose circumference was only partially within the cement mantle yielded a significantly lower number of cracks compared with screws positioned completely within the cement mantle or even touching the prosthetic stem. In order to reduce the incidence of crack formation in the cement mantle during plate osteosynthesis of periprosthetic femur fractures, the screws should not be either placed within the cement mantle or make direct contact with the stem.

Upcoming Paralympic summer games in Rio: what did the German medical team learn from the London Games?

BACKGROUND

Musculoskeletal complaints are frequently diagnosed in Paralympic athletes. Despite the increased professionalism in Paralympic Sports, the documentation of injuries and other health complaints during high-level competition is sparse. With respect to the upcoming Paralympic Summer Games in Rio de Janeiro, the aim of this study was the analysis of all musculoskeletal complaints within the German Paralympic Athletes during the London 2012 Paralympic Games.

METHODS

All musculoskeletal complaints (MSC) of the 150 German athletes seeking medical attention, hereby defined as "injury", were recorded during the in-competition period of the London Paralympics Games (22 days), regardless of their severity and consequences. Standardized documentation included the onset of symptoms, the medical diagnoses, the therapeutic measures taken as well as consecutive restrictions in training and competition. Incidence rates and localizations were analyzed by sports discipline.

RESULTS

A total of 201 musculoskeletal complaints were recorded for 140 athletes (93.3%), corresponding to 1.4 musculoskeletal complaints per "injured" athlete. The incidence of musculoskeletal complaints in German athletes was 62.9±15.4/1000 athlete-days. High incidence rates (IR) were observed in wheelchair basketball (IR 72/1000 athlete-days, 1.6 injuries per athlete) and equestrian events (IR 72.7, 1.6). Musculoskeletal complaints were mainly located in the upper extremities (37.6%) and the spine (37.6%). The most frequent diagnoses were myalgia (N.=105, 52%).

CONCLUSIONS

We noted a high rate of musculoskeletal complaints among German Paralympic athletes across sports and body parts, highlighting the need for prevention programs that focus on the upper extremities and spine.

When is the stability of a fracture fixation limited by osteoporotic bone?

This article is concerned with the search for threshold values for bone quality beyond which the risk of fixation failure increased. For trochanteric fractures we recognized a BMD lower than 250mg/cm(3) as an additional risk for cut out. For medial femoral neck fractures since joint replacement surgery is available and produces excellent functional results, we see no indication for further differentiation or analysis of bone quality in relation to fracture fixation. In the area of osteoporotic vertebral body fractures, there are many experimental studies that try to identify BMD limits of screw fixation in the cancellous bone on the basis of QCT analysis. However, these values have not yet been introduced for application in clinical practice. In case of indication for surgical fixation, we favor minimally invasive, bisegmental, fourfold dorsal instrumentation with screw-augmentation for a T-value less than -2.0 SD (DXA analysis, total hip or total lumbar spine). For proximal humerus fractures, BMD value of 95mg/cm(3) could be seen as a threshold value below which the risk of failure rises markedly. In relation to osteoporotic distal radius fractures, based on our clinical experience and scientific analyses there are virtually no restrictions as far as bone quality is concerned on the application of palmar locking implants in the surgical management of distal radius fractures. Optimization of preoperative diagnostics might help to revise the treatment algorithm to take bone density into account, thus reducing the risk of failure and, at the same time, acquiring additional data for future reference.

Long-Term Functional and Anatomical Outcome of Radial Optic Neurotomy for Central Retinal Vein Occlusion

BACKGROUND

Without treatment, the natural history of central retinal vein occlusion (CRVO) can result in severe loss of vision.

MATERIAL AND METHODS

This was a retrospective study of 10 eyes with CRVO treated with pars plana vitrectomy (PPV), combined with radial optic neurotomy. The patients completed a minimum of 5 years follow-up.

RESULTS

Median age at the time of surgery was 67 ± 14 years. Median follow-up was 79 ± 9 months. Ischaemic changes were present in 4 patients pre-operatively. Baseline median logMAR BCVA was 2.00 ± 0.76 and improved significantly to a median of 0.35 ± 0.54 (p < 0.0001, two tailed t test) at 5 years follow-up. The baseline median central macular thickness (CMT) was 645 ± 108 µm and improved significantly, to a median of 203 ± 72 µm (p < 0.0001, two tailed t test). One of the patients developed neovascular complications during the follow-up period.

CONCLUSIONS

Our results compare very favorably with the natural history of CRVO. All patients demonstrated a trend to improved visual acuity, while only one of the patients developed neovascular complications. These results provide information on the potential long-term effect of PPV in patients with CRVO and may help to reassess the place of the surgical management of CRVO in patients who do not respond to medical treatment.

Biomechanical comparison of different external fixator configurations for stabilization of supracondylar humerus fractures in children

BACKGROUND

Currently, closed reduction and percutaneous pinning are considered the treatment of choice for displaced supracondylar humerus fractures. However, indications exist for the use of external fixation with Schanz screws. In this in vitro study, we evaluate the biomechanical properties of a new variation for external fixation and compare them to an established construct.

METHODS

Twenty distal cadaver humeri (10 pairs) were allocated to 2 groups. The humeri of the first group were fixed by an external fixator consisting of Schanz screws and an oblique K-wire inserted from the distal radial cortex of the humerus, those of the second group were fixed by a new variation with the oblique K-wire inserted from the distal ulnar cortex of the humerus. Displacement and stiffness in static loading in internal and external rotation, as well as in extension and flexion were evaluated and compared.

FINDINGS

The variation of the external fixator of the second group proved to be statistically significantly superior to the variation of the first group in internal rotation loading (p>0.05). In sagittal loading conditions and external rotation loading, the variations were equally stable (p>0.05). There was no significant effect of the samples' bone density on displacement and stiffness values in any direction of loading.

INTERPRETATION

In cases of pediatric supracondylar humerus fractures when an external fixator is used for osteosynthesis, the insertion of an additional ulnarly inserted anti-rotation K-wire should be preferred to a radially inserted one as it reduces secondary displacement of the distal fragment.

Minimally invasive stabilization of distal humerus fractures: a pilot study with biomechanical evaluation

BACKGROUND

Fracture of the distal humerus is a fairly rare injury and makes high demands on the treating surgeon. Prerequisites for a good outcome are anatomical reconstruction and osteosynthesis stable enough for exercises. A method permitting early restoration of function is especially important for patients with osteoporosis. The extensive surgical approach necessary for open reduction is associated with a high number of wound healing disorders and infections with a frequency of 11% being reported in the literature. Although open reduction and internal fixation in double-plating technique is unavoidable for complex intraarticular fractures, an alternative, minimally invasive and, consequently, tissue-preserving procedure is desirable for simpler fractures.

OBJECTVE

To investigate this issue further an angular stable nail system developed for the distal radius was implanted as a stabilizer and the construct tested biomechanically as part of a feasibility study.

METHODS

Distal humerus fractures were stabilized by insertion of a distal radius nail, namely, the Targon DR (Aesculap, Tuttlingen) and a K-wire. To test the hypothesis six cadaveric bones fixed in formalin were tested biomechanically for displacement, implant failure, and stiffness. Displacement was determined by means of an ultrasound-based system.

RESULTS

An average displacement of 1.6 mm ± 0.7 was recorded at a maximum compression force of 100 N in extension and an average displacement of 1.4 mm ± 0.9 in flexion. Implant failure was not observed for any of the constructs.

CONCLUSIONS

The study presented here permits the conclusion that a minimally invasive procedure is possible at the distal humerus and does ensure adequate stability. Although the nail was not specifically designed for the humerus, current findings form the basis for a promising approach that will be pursued further after modification of the nail design.

Comparison of Multidetector Computed Tomography and Flat-Panel Computed Tomography Regarding Visualization of Cortical Fractures, Cortical Defects, and Orthopedic Screws: A Phantom Study

To compare the visualization of cortical fractures, cortical defects, and orthopedic screws in a dedicated extremity flat-panel computed tomography (FPCT) scanner and a multidetector computed tomography (MDCT) scanner.We used feet of European roe deer as phantoms for cortical fractures, cortical defects, and implanted orthopedic screws. FPCT and MDCT scans were performed with equivalent dose settings. Six observers rated the scans according to number of fragments, size of defects, size of defects opposite orthopedic screws, and the length of different screws. The image quality regarding depiction of the cortical bone was assessed. The gold standard (real number of fragments) was evaluated by autopsy.The correlation of reader assessment of fragments, cortical defects, and screws with the gold standard was similar for FPCT and MDCT. Three readers rated the subjective image quality of the MDCT to be higher, whereas the others showed no preferences.Although the image quality was rated higher in the MDCT than in the FPCT by 3 out of 6 observers, both modalities proved to be comparable regarding the visualization of cortical fractures, cortical defects, and orthopedic screws and of use to musculoskeletal radiology regarding fracture detection and postsurgical evaluation in our experimental setting.

[Lateral hinge fractures in open wedge high tibial osteotomy]

BACKGROUND

Open wedge high tibial osteotomy (HTO) is an increasingly more common surgical method. A typical problem of this procedure is fracture of the lateral hinge.

OBJECTIVES

The aims of this article are to present the special issue of fractures of the lateral hinge after HTO and to discuss surgical hints on how to prevent and treat this problem.

METHODS

The results of recently published clinical studies are summarized and tips from own clinical experiences are given.

RESULTS

Type II fractures of the lateral hinge are unstable and can create a major problem. Using short spacer plates results in a problem of stability for all types of fractures.

CONCLUSION

The classification into Takeuchi grades I-III has been proven to be suitable for fractures of the lateral hinge. The TomoFix plate is a safe implant to stabilize the osteotomy in type I and III fractures with which healing can be achieved with no problems. Type II fractures can be stabilized with the TomoFix plate; however, an autologous bone graft has to be taken into consideration. For fractures of the lateral hinge short spacer plates are not recommended due to stability issues.

Relationship between autologous bone graft osteointegration and correction loss after antero-posterior spondylodesis of traumatic vertebral body fracture

BACKGROUND

A common method to restore the sagittal alignment and stabilize the spinal column is a dorso-ventral spondylodesis. It is assumed that correction loss after posttraumatic spondylodesis results from inadequate incorporation of the autologous iliac crest graft.

MATERIALS AND METHODS

Retrospective documentation of patients with unstable vertebral body fractures of the thoracic or lumbar spine with concomitant rupture of at least one adjacent intervertebral disk who received surgical treatment at our institution from 2000 to 2006. Followed by analysis of the computer tomography documentation of a total of 142 patients with unstable vertebral body fracture stabilized by posterior internal fixator and anterior iliac crest spondylodesis.

RESULTS

The following mean angle changes were derived from the second series of CT scans performed on average 283 days after anterior spondylodesis: vertebral wedge angle (VWA): 2.1°; segmental kyphotic angle: 4.9°; adjusted-SKA: 4.8°; sagittal index (SI): -0.04; segmental-scoliotic-angle (SSA): 0°; adjusted-SSA: 0°. Changes in VWA, both SKAs and SI postoperatively and prior to ME, were statistically significant (P<0.05). The McAfee fusion assessment of the graft showed: full fusion: cranial 64%, caudal 47%; partial fusion: cranial 20.5%, caudal 29%; lysis: cranial 8.5%, caudal 17%; graft resorption: 7%. No correlation was found between the above-mentioned angle changes and fusions grade.

DISCUSSION

The importance of radiological evidence of fusion deficiency is questionable, because the extent of fusion only has a minimal effect on correction loss.

LEVEL OF EVIDENCE

Level IV.

Biomechanical evaluation of two innovative locking implants for comminuted olecranon fractures under high-cycle loading conditions

INTRODUCTION

The relatively high complication rate after fixation of olecranon fractures has led to an increasing application of anatomically pre-contoured locking plate systems. The purpose of the present study was to conduct a biomechanical comparison of olecranon osteosyntheses by applying the Olecranon VA-LCP and the 3.5mm LCP Hook Plate (LCP, locking compression plate) to an unstable fracture model under high-cycle loading conditions.

METHODS

After creating an unstable fracture (Schatzker type B), osteosynthesis was performed on eight pairs of fresh-frozen cadaveric ulnae by application of either the Olecranon VA-LCP (Synthes, Solothurn, Switzerland) or the 3.5mm LCP Hook Plate (Synthes, Solothurn, Switzerland). Loading (50,000 alternating loads, cyclic and sinusoidal 10-300 N) was conducted by application of tensile load with the elbow in 90° flexion to simulate the tensile strength of the triceps brachii. For statistical analysis, angular displacement in the region of the humeral trochlea was taken as a measure of olecranon dislocation.

RESULTS

In Group 1 (Olecranon VA-LCP), a median angular displacement of 0.36° (minimum 0.10°; maximum 0.80°) was observed after 500 alternating loads. In Group 2 (3.5-mm LCP Hook Plate), the medial displacement was 0.80° (minimum 0.13°; maximum 2.72°). The difference was nonsignificant (p = 0.128). The mean value for angular displacement in Group 1 after 50,000 cycles was 0.80° (minimum 0.31°; maximum 1.99°), whereas in Group 2 a mean angular displacement of 2.02° (minimum 0.71°; maximum 6.40°) was recorded. The difference was statistically significant (p = 0.017). In Group 2, implant failure in the form of proximal plate pullout occurred in one construct after 756 cycles.

CONCLUSION

A significantly higher biomechanical stability can be achieved in the fixation of unstable olecranon fractures by application of the Olecranon VA-LCP rather than the 3.5mm LCP Hook Plate.

Smoking and unstable hinge fractures cause delayed gap filling irrespective of early weight bearing after open wedge osteotomy

PURPOSE

The purpose of this study was to examine the osteotomy gap filling rate with new bone after open wedge high tibial osteotomy (HTO) without bone graft and the effects of smoking, lateral hinge fracture, and early full weight bearing.

METHODS

A prospective series (N = 70) of open wedge HTOs with the TomoFix plate (DePuy Synthes, Umkirch, Germany) was performed. Radiologic follow-up examinations took place postoperatively, after 6 and 12 weeks, and after 6, 12, and 18 months to measure osteotomy gap filling at each follow-up. Bone healing was compared in smokers versus nonsmokers who underwent open wedge HTOs with intact lateral hinges. Fractured lateral hinges were classified according to the Takeuchi classification and separately analyzed regarding bone healing. Patients were randomly assigned to undergo early (11 days) or standard (6 weeks) full-weight-bearing rehabilitation.

RESULTS

A delay in the osteotomy gap filling rate between smokers and nonsmokers could be observed at all follow-up periods, but differences were not significant. A fracture of the lateral hinge was found in 39% of the patients. A type I fracture was observed in 14% of patients, a type II fracture was observed in 13%, and a type III fracture was found in 6%. The highest increase in the osteotomy gap filling rate was observed between 12 weeks and 6 months after surgery in patients with intact lateral hinges. For patients with unstable type II fractures, the highest increase in the gap filling rate was delayed until 6 to 12 months. Early full weight bearing had no effect on the gap filling rate in any of the patient groups evaluated.

CONCLUSIONS

This study shows that osteotomy gap filling after open wedge HTO is delayed in smokers and in patients in whom opening of the gap resulted in unstable lateral hinge fractures. Early full weight bearing did not have a significant effect on the gap filling rate.

LEVEL OF EVIDENCE

Level III, prognostic study.

Sliding of the load carrier in third-generation intramedullary nails for proximal femur fractures: an in vitro mechanical comparison study

Dynamic osteosynthesis of proximal femur fractures facilitates compression at the fracture site through distal glide of the femoral head load carrier in the intramedullary nail. Modern implants are currently designed according to diverse gliding principles. The aim of this study was to compare the sliding mechanisms of different types of nails. As in other similar mechanical studies the load patterns occurring around the femoral head load carrier and the intramedullary nail under full load were simulated for three different types of intramedullary nail - PFNA, Targon PFT and Trigen Intertan. The load necessary to trigger distal displacement of the femoral head implant in the nail was determined. The lengths of the load carriers were varied. For the three lengths of load carrier, mechanical testing showed that the Targon PFT started to slide at a significantly lower load compared to the other two implants. Comparison of the PFNA and Trigen Intertan in terms of load to dynamization for 77 mm carriers revealed a significantly lower load for the PFNA. Slide efficacy for the PFNA and the Trigen Intertan was found to improve as the length of the blade/screw was shortened. The dynamization properties of the Targon PFT with its cylindrical sliding mechanism, similar to the DHS, were far better compared to the PFNA and the Trigen Intertan that have more complex sliding actions. Since theoretical considerations indicate that a less efficient gliding action leads to a higher complication rate, implants of the next generation should be optimized in this regard.

Biomechanical testing of an innovative fixation procedure to stabilize olecranon osteotomy

For the treatment of distal humerus an approach involving olecranon osteotomy is frequently preferred as it offers a clearer view, especially in cases of complex intraarticular fractures. It is however associated with the high risk of osteotomy-related complications such as nonunion, delayed healing, implant failure and migration of wires. The aim of the present study was to evaluate the stability of different new procedures that stabilize olecranon osteotomy compared with conventional tension band wiring. We hypothesize that the new implants provide equivalent stability as the conventional tension band wiring. To test the hypothesis 27 biomechanically evaluated synthetic ulnae were osteotomized and stabilized with either the application of tension band wiring, the Olecranon Hook LCP (Synthes, Switzerland), or the Olecranon Osteotomy nail (Synthes, Switzerland). Loading was performed providing a tensile load to simulate the tensile force applied by the triceps muscle. Cyclic force-controlled loading was performed at 300 alternating forces between 10N and 500N at a speed of 200N/sec. An ultrasound-based system measured displacement to an accuracy of 0.1 mm. Statistical analysis showed significantly less displacement in the Olecranon Hook LCP and Olecranon Osteotomy nail groups compared with tension banding. Comparison of plate and nail yielded no differences in stability. Biomechanical testing did however show significantly higher stability for newer fixation methods for olecranon osteotomies compared with the frequently applied technique of tension band wiring. Whether the use of these implants will also lower complication rates remains to be evaluated in future clinical studies.

Level of evidence: Basic Science Study, Biomechanical Study.

Digital templating in total knee and hip replacement: an analysis of planning accuracy

PURPOSE

The aim of this study was to determine how well pre-operative size selection for total knee and hip arthroplasties based on the digital imaging with and without additional referencing correlated with the size actually implanted.

METHODS

Size selection planning of total knee arthroplasty by digital templating was documented in 46 cases with reference ball (group A) and in 48 cases without ball (group B). In addition, prospective analysis of pre-operative planning was conducted for 52 acetabular components with reference ball (group C) and 69 without ball (group D) as well as stem planning in 38 cases with ball (group E) and 54 cases without ball (group F). The data were analysed and compared with the size of the final component selected during surgery.

RESULTS

The correlation between planned and implanted size for total knee arthroplasty in group A resulted in femoral anteroposterior (AP) r = 0.8622 and lateral r = 0.8333 and in group B AP r = 0.4552 and lateral r = 0.6950. Tibial in group A was AP r = 0.9030 and lateral r = 0.9074 and in group B AP r = 0.7000 and lateral r = 0.6376. For the acetabular components, the results in group C were r = 0.5998 and group D r = 0.6923. For stems, group E was r = 0.5306 and group F r = 0.5786. No correlation between BMI and the difference between planned and implanted size was found in any of the groups.

CONCLUSION

In the case of total hip arthroplasty there was a relatively low correlation between planned and implanted sizes with or without reference ball. For total knee arthroplasties the already high precision of size planning was further improved by the additional referencing with a reference ball.

Failure after osteosynthesis of trochanteric fractures. Where is the limit of osteoporosis?

SUMMARY

The aim of this study is to identify osteoporosis values, beyond which there is a high risk of osteosynthesis failure. Bone mineral density (BMD) of 30 cadaveric femora with a pertrochanteric fracture osteotomy was correlated to the risk of cut out after osteosynthesis on a biomechanical testing approach. For a BMD less than 250 mg/cm(3), there is a high risk of fixation failure after surgical treatment of pertrochanteric fractures. This value can be regarded as a reference value for future experimental and clinical studies.

INTRODUCTION

Despite continuous modification of intramedullary load carriers for the surgical stabilization of trochanteric fractures, cut out remains the most frequent complication. The aim of this experimental study was to identify threshold osteoporosis values, beyond which there is a high risk of osteosynthesis failure.

METHODS

Bone mineral density (BMD) of 30 cadaveric femora was recorded for the femoral head by QCT measurement. Subsequently, a standardized osteotomy mimicking an unstable trochanteric type fracture was stabilized by intramedullary nailing. The constructs were loaded axially at a force of 2,100 N up to 20,000 cycles. Cut out at the femoral head was documented by radiograph. Statistical evaluation of the cohort group was performed by calculation of relative risk in relation to the BMD values.

RESULTS

In total, there were six cases of cut out after 10,000 cycles. The incidence of cut out for BMD less than 250 mg/cm(3) was 0.55 (5 of 9) and for BMD greater than 250 mg/cm(3), it was 0.05 (1 of 21). Therefore, the relative risk of cut out for BMD <250 mg/cm(3) is 11× greater than for a BMD >250 mg/cm(3). After 20,000 cycles, an additional test caused one cut out (relative risk of cut out for a BMD <250 mg/cm(3) 5.8).

CONCLUSIONS

For a BMD less than 250 mg/cm(3), there is a high risk of fixation failure after surgical treatment of pertrochanteric fractures. Although this value is based on an experimental in vitro study design with all its associated limitations, it can be regarded as a reference value for future experimental and clinical studies.

Intramedullary nailing of trochanteric fractures: central or caudal positioning of the load carrier? A biomechanical comparative study on cadaver bones

BACKGROUND

Current recommendations with regard to central or caudal positioning of the femur head carrier in the management of trochanteric fractures are contradictory.

METHODS

A standardised pertrochanteric osteotomy was stabilised in 15 pairs of cadaver femurs by means of intramedullary osteosynthesis (5xPFN-A-Synthes, 5xIntertan-Smith&Nephew, 5xTargon-PF-Aesculap). For each pair randomised central (group A) or caudal (group B) implantation of the femoral neck component was performed. Subsequently, the constructs were axially loaded to 2100N. In the absence of cut out after 20,000 cycles, load was increased to a maximum force of 3100N. Angular displacement was recorded based on ultrasound. Migration of the load carrier in the femoral head was monitored radiologically.

FINDINGS DISPLACEMENT

No significant difference between groups (p>0.15) was found for the first 50 load cycles. A significantly greater degree of varus deformity was observed in group A (p=0.049) after 2000 load cycles and became more apparent as the number of load cycles increased (after 6000 cycles p=0.039, after 20,000 cycles p=0.034, after 22,000 cycles p=0.016). Angular displacement in the other two planes did not differ significantly across groups. CUT OUT: Migration of the load carrier in the femoral head was not significantly different for the two groups. Overall cut out occurred in 9 constructs, 3 in group A and 6 in group B. The difference in cut-out rate was not significant (p=0.213, chi-squared test).

CONCLUSION

Biomechanical superiority can be shown for caudal positioning of the femoral neck load carrier in terms of reduced varus deformity. The incidence of cut out is however unaffected by the position of the load carrier.

Tibial cleaning method for cemented total knee arthroplasty: An experimental study

BACKGROUND

The survival rate of cemented knee prosthesis depends among other factors on optimal cement-bone contact, nevertheless no standard exists for cementing technique of tibial components. The aim of this study was to determine which tibial surface preparation technique leads to the best bone-cement contact.

MATERIALS AND METHODS

HUMAN TIBIAL PLATEAU SPECIMENS WERE CLEANED IN FOUR DIFFERENT WAYS BEFORE CEMENTING: a) no cleaning, b) manual syringe irrigation, c) fracture brush cleaning, and d) pulsatile jet-lavage. The specimens were cut into transverse sections and the bone cement contact distance was calculated for every 10 mm and the cement penetration depth was measured. Both values were statistically analyzed (ANOVA).

RESULTS

The longest bone-cement contact (62 mm) was seen after PJL, the shortest (10.6 mm) after no cleaning at all. The deepest cement penetration (4.1 mm) again was seen after PJL, the least (0.7 mm) after no cleaning. Statistically, PJL yielded the longest bone-cement contact and deepest cement penetration.

CONCLUSION

The results supports the use of pulsatile jet-lavage before cementing tibial components in knee arthroplasty.

Modular sleeves with ceramic heads in isolated acetabular cup revision in younger patients-laboratory and experimental analysis of suitability and clinical outcomes

PURPOSE

One possibility in hip arthroplasty revisions is to combine a modular ceramic head with an adapter or sleeve in isolated acetabular cup replacement. This study consisted of an experimental part to analyse the reliability of taper damage predictions, and a clinical part to analyse the outcomes of modular ceramic head implantation in a case series of isolated cup replacements.

METHODS

Analysis of scratch size on 11 explanted hip stems were examined macroscopically and by stereomicroscopy to classify damage to the conical taper. The second part consisted of a prospective analysis of isolated cup revisions using a modular ceramic head, performed in two orthopedic centres.

RESULTS

Analysis of scratch size on the taper yielded inter-observer correlations of 0.545-0.909; comparison with stereomicroscopic data recordings yielded a moderate correlation, with values between 0.545 and 0.090. The clinical study included 47 isolated acetabular cup revisions involving modular ceramic heads. Ceramic head failure did not occur during the average clinical and radiological observation period of 26 months. Mean Harris Hip Score (HHS) at follow-up was 70 points.

CONCLUSION

From these results, it can be concluded that damage to the implanted stem taper cannot be reliably predicted intraoperatively. Nevertheless, the clinical outcomes did show that there were no problems with the ceramic heads over the short observation period. The application of modular ceramic heads in younger patients requiring isolated cup replacement requires proper risk-benefit analysis, but is possible and appears to be a safe procedure.

Effects of radiotherapy on uveal melanomas and adjacent tissues

Most uveal melanomas are treated with radiotherapy. An adequate understanding of the effects of radiation on the tumour and the healthy ocular tissues is necessary. Ionizing radiation damages cell membranes, organelles, and DNA. Irradiated cells are lysed or undergo apoptosis, necrosis, and senescence. These effects occur in tumour cells and vascular endothelial cells, resulting in tumour shrinkage, ischaemia, infarction, exudation, and fibrosis, which can cause exudative maculopathy, serous retinal detachment, rubeosis, and neovascular glaucoma (ie, 'toxic tumour syndrome'). Such abnormalities must be distinguished from collateral damage to healthy ocular tissues that receive high doses of radiation, and these include radiation-induced retinopathy, optic neuropathy, choroidopathy, cataract, and scleral necrosis. Radiation retinopathy can be treated effectively with photodynamic therapy, anti-angiogenic agents, and intravitreal steroid injections. In some patients, optic neuropathy may improve with intravitreal steroids or anti-angiogenic agents. Neovascular glaucoma resolves with intra-cameral bevacizumab. Exudative retinal detachment can regress with intra-vitreal steroid injections. Cataract is treated in the usual manner. Scleral necrosis, if severe, may require grafting, possibly using a lamellar flap from the same eye. Depending on the bulk of the residual toxic tumour, treatment can consist of intra-vitreal steroids and/or anti-angiogenic agents, transpupillary thermotherapy or photodynamic therapy to the tumour, or surgical removal of the tumour by endo- or exo-resection. Measures aimed at preventing collateral damage include eccentric placement of ruthenium plaques or iodine seeds and delivery of a notched proton beam. The decision to treat a uveal melanoma with radiotherapy requires the ability to manage iatrogenic side effects and complications.

Prognostic value of Achilles tendon Doppler sonography in asymptomatic runners

INTRODUCTION

Midportion Achilles tendinopathy (MPT) is a common problem in running athletes. Nevertheless, its etiology is not fully understood, and no valid prognostic criterion to predict the development of MPT could be identified to date. The purpose of the present study, therefore, was to evaluate whether power Doppler ultrasonography (PDU) is a suitable method to identify a predisposition to MPT in yet asymptomatic runners.

METHODS

At 23 major running events, 634 asymptomatic long-distance runners were tested for Achilles tendon thickness, vascularization, and structural abnormalities using a high-resolution PDU device (Toshiba Aplio SSA-770A/80, 12 MHz). In addition, their medical history and anthropometric data were documented. All subjects were contacted 6 and 12 months later and asked about any new symptoms. The collected anamnestic, anthropometric, and ultrasonographic data were subjected to regression analysis to determine their predictive value concerning the manifestation of midportion Achilles tendon complaints (P < 0.05).

RESULTS

The highest odds ratio (OR) for manifestation of MPT within 1 yr was found for intratendinous blood flow ("neovascularization," OR = 6.9, P < 0.001). An increased risk was also identified for subjects with a positive history of Achilles tendon complaints (OR = 3.8, P < 0.001). A third relevant parameter, just above the level of significance, was a spindle-shaped thickening of the tendon on PDU (Wald χ2 = 3.42).

CONCLUSIONS

PDU detection of intratendinous microvessels in the Achilles tendons of healthy runners seems to be a prognostically relevant factor concerning the manifestation of symptomatic MPT. This finding lays the foundation for an early identification of a predisposition to MPT as well as prophylactic intervention in as yet asymptomatic runners.

Effects of muscle-equivalent forces on the biomechanical behavior of proximal femur fracture models: a pilot study on artificial bones

Introduction:

There has been extensive analysis of the influence of muscle forces and their effects on the biomechanical behavior of the proximal femur. Nevertheless, these forces have only been taken into account in a handful of biomechanical studies in the field of traumatology. The aim of this study was to analyze the biomechanical behavior of two typical fracture models of the proximal femur based on muscle-equivalent forces.

Method:

Plate osteosynthesis was performed on two groups of artificial femora to stabilize either a trochanteric osteotomy ( n = 5) or a femur shaft osteotomy ( n = 5). After fixation axial loading was applied to the constructs first without muscle-equivalent forces and then with the addition of these forces (abductor groups and vastus lateralis). Displacement at the osteotomy site and the stiffness of the whole construct were measured during loading.

Results:

Comparison of the two loading modes revealed no significant differences for displacement or stiffness for the trochanteric fractures. For the femur shaft fractures, a significant difference was found for displacement ( p = 0.023) and stiffness ( p = 0.003) with or without muscle-equivalent forces.

Conclusion:

The loading protocol for implant testing on femur shaft fractures should include muscle-equivalent forces. For trochanteric fractures, consideration of muscle forces is not entirely necessary since they will have little effect on the results, for example, when comparing implants.

Internal fixation of dorsally comminuted fractures of the distal part of the radius: a biomechanical analysis of volar plate and intramedullary nail fracture stability

INTRODUCTION

The purpose of the present study was to carry out biomechanical testing of "new generation" volar plates and an intramedullary nail.

METHODS

Four volar locking plates (Column Plate, VariAx distal radius, 2.4 mm-LCP and 3.5 mm-LCP) and the intramedullary nail, Targon-DR, were implanted in biomechanically validated artificial bones after simulation of a wedge osteotomy with total transection of the volar cortex to mimic a type 23 A3-fracture according to the AO-classification. Axial load (250 Newton [N]) and volar and dorsal bending loads (both 50 N) were applied. Axial load was increased to fixation failure. Gap motion was measured three-dimensionally directly at the fracture gap. The 3.5 mm-LCP was used for comparison as it currently represents an established locking implant that has been well tested biomechanically.

RESULTS

In this experimental setting, the 2.4 mm-LCP showed the lowest resistance under all three loading modi and, consequently, the highest level of motion at the osteotomy gap in comparison to all other implants (p < 0.05). Under axial loading, there were no significant differences between the other four implants. Under dorsal bending, the Targon-DR-nail and the VariAx-plate showed less gap displacement in comparison to the 3.5 mm-LCP (p < 0.05). Under volar bending, only the Targon-nail showed greater resistance than the 3.5 mm-LCP (p < 0.05) with no other significant differences between the Column Plate, the VariAx and the 3.5 mm-LCP.

CONCLUSION

In this experimental setting, all "new generation" implants for distal radius fractures with the exception of the 2.4 mm-LCP showed identical or higher stability compared to the 3.5 mm-LCP. The 2.4 mm-LCP showed the lowest resistance and this must be taken into consideration when planning postoperative functional therapy.