Environmental drivers of increased ecosystem respiration in a warming tundra

Arctic and alpine tundra ecosystems are large reservoirs of organic carbon1,2. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere3,4. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain5-7. This hampers the accuracy of global land carbon-climate feedback projections7,8. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9-2.0 °C] in air and 0.4 °C [CI 0.2-0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22-38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.

Differential locomotor activity responses to day-time light intensity in juvenile and adult solitary Cape mole-rats, Georychus capensis (Rodentia: Bathyergidae)

The Cape mole-rat (Georychus capensis) is a solitary, strictly subterranean rodent that is responsive to light and entrains to photic cues despite having a reduced visual system. Circadian entrainment is maintained throughout life, but age can alter the amplitude of the response and re-entrainment time. Mole-rats are long-lived for their size which raises questions regarding the robustness of their circadian rhythms and how impacts their locomotor activity rhythms. The locomotor activity rhythms of juvenile and adult Cape mole-rats were investigated. They were exposed to pre-experimental and post-experimental control cycles under fluorescent lights, six 12 h light:12 h dark cycles of decreasing intensities and a constant dark cycle (DD). All animals exhibited more activity during the dark phases of all light regimes. Juveniles were more active than adults and displayed more variable activity during both the light and dark phases. Adults exhibited relatively stable levels of activity under all experimental conditions, whereas juvenile activity decreased as the light intensity was reduced. The amplitude of Cape mole-rat rhythms was consistently low, but similar across light regimes and between adults and juveniles. Cape mole-rats have functional circadian systems, are primarily nocturnal and respond differentially to light intensity depending on their age. Light intensity does not affect the locomotor activity responses of Cape mole-rats in a predictable manner, and could indicate more complex interactions with light wavelengths. The circadian systems of juveniles appear to be more sensitive than those of adults, although the mechanism of the light response remains unclear.

Thawing Yedoma permafrost is a neglected nitrous oxide source

In contrast to the well-recognized permafrost carbon (C) feedback to climate change, the fate of permafrost nitrogen (N) after thaw is poorly understood. According to mounting evidence, part of the N liberated from permafrost may be released to the atmosphere as the strong greenhouse gas (GHG) nitrous oxide (N₂O). Here, we report post-thaw N₂O release from late Pleistocene permafrost deposits called Yedoma, which store a substantial part of permafrost C and N and are highly vulnerable to thaw. While freshly thawed, unvegetated Yedoma in disturbed areas emit little N₂O, emissions increase within few years after stabilization, drying and revegetation with grasses to high rates (548 (133–6286) μg N m⁻² day⁻¹; median with (range)), exceeding by 1–2 orders of magnitude the typical rates from permafrost-affected soils. Using targeted metagenomics of key N cycling genes, we link the increase in in situ N₂O emissions with structural changes of the microbial community responsible for N cycling. Our results highlight the importance of extra N availability from thawing Yedoma permafrost, causing a positive climate feedback from the Arctic in the form of N₂O emissions.

During permafrost thaw, nitrogen can be released as the greenhouse gas nitrous oxide, but the magnitude of this flux is unknown. Nitrous oxide emissions from ice-rich permafrost deposits are reported here, showing that emissions increase after thawing and stabilization and could represent an unappreciated positive climate feedback in the Arctic.

Augmenting the Immune Response against a Stabilized HIV-1 Clade C Envelope Trimer by Silica Nanoparticle Delivery

The delivery of HIV-1 envelope (Env) trimer-based immunogens on the surface of nanoparticles holds promise to promote immunogenicity with the aim of inducing a potent, durable and broad neutralizing antibody (bnAb) response. Towards that goal, we examined the covalent conjugation of Env to 100 nm and 200 nm silica nanoparticles (SiNPs) to optimize conjugation density and attachment stability. Env was redesigned to enable site-specific cysteine-mediated covalent conjugation while maintaining its structural integrity and antigenicity. Env was anchored to different sized SiNPs with a calculated spacing of 15 nm between adjacent trimers. Both particle sizes exhibited high in vitro stability over a seven-day period. After attachment, 100 nm particles showed better colloidal stability compared to 200 nm particles. Importantly, the antigenic profile of Env was not impaired by surface attachment, indicating that the quaternary structure was maintained. In vitro Env uptake by dendritic cells was significantly enhanced when Env was delivered on the surface of nanoparticles compared to soluble Env. Furthermore, multivalent Env displayed efficiently activated B cells even at Env concentrations in the low nanomolar range. In mice, antibody responses to nanoparticle-coupled Env were stronger compared to the free protein and had equivalent effects at lower doses and without adjuvant.

Aviation Contrail Cirrus and Radiative Forcing Over Europe During 6 Months of COVID-19

The COVID-19 pandemic led to a 72% reduction of air traffic over Europe in March-August 2020 compared to 2019. Modeled contrail cover declined similarly, and computed mean instantaneous radiative contrail forcing dropped regionally by up to 0.7 W m-2. Here, model predictions of cirrus optical thickness and the top-of-atmosphere outgoing longwave and reflected shortwave irradiances are tested by comparison to Meteosat-SEVIRI-derived data. The agreement between observations and modeled data is slightly better when modeled contrail cirrus contributions are included. The spatial distributions and diurnal cycles of the differences in these data between 2019 and 2020 are partially caused by differences in atmospheric and surface conditions, particularly for solar radiation in the spring of 2020. Aviation signals become discernible in the observed differences of these data between 2019 and 2020 when subtracting numerical weather prediction model results that approximate the atmosphere and surface conditions without contrails.

Author Correction: The evolution of 17O-excess in surface water of the arid environment during recharge and evaporation

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Reproductive status-dependent kisspeptin and RFamide-related peptide (Rfrp) gene expression in female Damaraland mole-rats

Damaraland mole rats (Fukomys damarensis) are cooperatively breeding, subterranean mammals that exhibit a high reproductive skew. Reproduction is monopolised by the dominant female of the group, whereas subordinates are physiologically suppressed to the extent that they are anovulatory. In these latter animals, it is assumed that normal gonadotropin-releasing hormone secretion from the hypothalamus is disrupted. The RFamide peptides kisspeptin (Kiss1) and RFamide-related peptide-3 (RFRP-3) are considered as potent regulators of gonadotropin release. To assess whether these neuropeptides are involved in the mechanism of reproductive suppression, we investigated the distribution and gene expression of Kiss1 and Rfrp by means of in situ hybridisation in wild-caught female Damaraland mole-rats with different reproductive status. In both reproductive phenotypes, substantial Kiss1 expression was found in the arcuate nucleus and only few Kiss1-expressing cells were detected in the anteroventral periventricular nucleus (AVPV), potentially as a result of low circulating oestradiol concentrations in breeding and nonbreeding females. Rfrp gene expression occurred in the dorsomedial nucleus, the paraventricular nucleus and the periventricular nucleus. While in female breeders and nonbreeders, plasma oestradiol levels were low and not significantly different, quantification of the hybridisation signal for both genes revealed significant differences in relation to reproductive status. Reproductively active females had more Kiss1-expressing cells and a higher number of silver grains per cell in the arcuate nucleus compared to nonreproductive females. This difference was most pronounced in the caudal part of the nucleus. No such differences were found in the AVPV. Furthermore, breeding status was associated with a reduced number of Rfrp-expressing cells in the anterior hypothalamus. This reproductive status-dependent expression pattern of Kiss1 and Rfrp suggests that both neuropeptides play a role in the regulation of reproduction in Damaraland mole-rats. Enhanced long-term negative feedback effects of oestradiol could be responsible for the lower Kiss1 expression in the arcuate nucleus of reproductively suppressed females.

Cement augmentation of humeral head screws reduces early implant-related complications after locked plating of proximal humeral fractures

Background

Cement augmentation (CA) of humeral head screws in locked plating of proximal humeral fractures (PHF) was found to be biomechanically beneficial. However, clinical outcomes of this treatment have not been well evaluated to date.

Objectives

To assess outcomes of locked plating of PHF with additional CA and to compare them with outcomes of conventional locked plating without CA.

Methods

24 patients (mean age, 74.2 ± 10.1 years; 22 female) with displaced PHF were prospectively enrolled and treated with locked plating and additional CA. The Constant score (CS), the Simple Shoulder Test (SST), and the Simple Shoulder Value (SSV) were assessed 3 and 12 months postoperatively. Fracture healing and potential complications were evaluated on postoperative radiographs. The CS and complications were compared with the outcomes of a matched group of 24 patients (mean age, 73.9 ± 9.4 years; 22 female) with locked plating of displaced PHF without CA.

Results

At the 3‑month follow-up, the mean CS was 59.9 ± 15.6 points, the mean SST was 7.5 ± 2.7 points, and the mean SSV was 63.9 ± 21.7%. All scores significantly improved by the 12-month follow-up (p < 0.05; CS, 72.9 ± 17.7; SST, 9.2 ± 3.2; SSV, 77.2 ± 17.3%). There were two cases (8%) of biological complications (n = 1 varus malunion and n = 1 humeral head necrosis). Compared with locked plating without CA, no significant differences were observed between the CS at the 3‑ (57.8 ± 13.4 points; p = 0.62) and 12-month (73.0 ± 12.8 points; p = 0.99) follow-up. However, patients without CA had a significantly increased risk of early loss of reduction and articular screw perforation (p = 0.037).

Conclusion

Locked plating of proximal humeral fractures with trauma cement augmentation of humeral head screws could be translated from the ex-vivo lab setting into the clinical situation without additional complications. Locked plating of displaced PHF with additional cement augmentation showed similar clinical outcomes but reduced the rate of early implant-related complications compared to locked plating without additional CA.

[Injuries of the acromioclavicular joint: Hook plate versus arthroscopy]

Acute acromioclavicular (AC) joint injuries are common in clinical practice. The hook plate is a well-established conventional operative treatment option for high grade instability; however, arthroscopically-assisted flexible double button techniques are increasingly being used. Both procedures lead to good or excellent results. The advantages of the hook plate are the simple surgical technique and the possibility of an early functional aftercare. The minimally invasive one-step procedure with the possibility of identification and treatment of frequently concomitant glenohumeral pathologies is advantageous for the arthroscopic technique but mobilization is more restrictive. Available comparative studies have shown no significant clinical differences but a tendency towards better results with a higher degree of acceptance among patients for the arthroscopic and minimally invasive non-rigid double button procedures.

Population pharmacokinetics of a new long-acting recombinant coagulation factor IX albumin fusion protein for patients with severe hemophilia B

Essentials The new recombinant factor IX (FIX) albumin fusion protein (rIX-FP) has a prolonged half-life. A population pharmacokinetic (PK) model was based on FIX activity levels of hemophilia B patients. The model was used to simulate different dosing scenarios of rIX-FP to help guide dosing. The population PK model supported prolonged dosing of rIX-FP with intervals of up to 2 weeks. Click to hear Prof.Makris's presentation on new treatments in hemophilia SUMMARY: Background The recombinant fusion protein linking recombinant coagulation factor IX with recombinant albumin (rIX-FP; Idelvion® ) exhibits a longer half-life than plasma-derived factor IX (FIX) and the commercially available recombinant FIX products. Objectives (i) Characterize the population pharmacokinetics (PK) of rIX-FP in hemophilia B patients, (ii) identify covariates that are potential determinants of rIX-FP PK variability and (iii) simulate different dosing scenarios of rIX-FP following single and steady-state dosing. Patients/Methods A population PK model was developed based on FIX activity levels of 104 patients who had received treatment with rIX-FP. Patients were aged 1-65 years with FIX activity ≤ 2 IU dL-1 . PK sampling was performed for up to 14 days (336 h). Results Simulation of a single intravenous infusion of rIX-FP (25-75 IU kg-1 ) predicted that the median trough exogenous FIX activity levels would remain > 5 IU dL-1 for up to 16 days in adolescents/adults aged ≥ 12 years, up to 12 days in children aged 6 to < 12 years, and up to 9.5 days in children aged < 6 years. For steady-state dosing, the median trough exogenous FIX activity levels were maintained at > 5 IU dL-1 for the duration of the dosing interval for the 25, 35 and 40 IU kg-1 weekly regimens and for 75 IU kg-1 every 14 days in adolescents/adults, and for the 35 and 40 IU kg-1 weekly regimens in children. Conclusion The population PK model developed here correlates well with observed clinical data and supports prolonged dosing of rIX-FP with intervals of up to 2 weeks.

[Prehospital analgesia by paramedics in Rhineland-Palatinate : Feasability, analgesic effectiveness and safety of intravenous paracetamol]

BACKGROUND

In contrast to the widespread practice in life-threatening emergencies, delegation of medical pain therapy to paramedics by the medical director  of Emergency Medical Services, EMS, are still the exception in Germany. This is due to the fact that in non-life-threatening situations, the expected benefit and potential side effects of drug therapy have to be carefully weighed. In addition, in Germany federal law generally restricts the administration of opiates to physicians.

METHODS

In 2011 the medical directors of EMS in the German state of Rhineland- Palatinate (4 million inhabitants) developed and implemented a standard operating procedure (SOP) for paramedics related to the prehospital parenteral administration of paracetamol for patients with isolated limb trauma. After a 2 h training session and examination, paramedics were authorized to administer 1 g of paracetamol to patients with a pain score > 5 points on an 11-point numerical rating scale (NRS). For purposes of quality management, every administration of paracetamol had to be prospectively documented on a specific electronic mission form.

RESULTS

A total of 416 mission forms could be analyzed. After administration of paracetamol the median NRS score decreased from 8 points (interquartile range: 6; 8) to 4 points (interquartile range: 3; 7). In 51.2 % of the patients the pain intensity was reduced by at least 3 NRS points and in 50.5 % of the patients the NRS was less than 5 points after treatment. The extent of pain reduction was positively correlated with the initial NRS value (r = 0.31, p < 0.0001). No serious side effects were noted. The percentage of patients with an initial heart rate > 100/min declined from 14.6 % to 5.2 % after the administration of paracetamol (p < 0.0001), 18.7 % of the patients received paracetamol for trauma not related to the extremities and 7 % of the patients for nontraumatic pain. An emergency physician was involved in 50 % of the EMS missions and 98.6 % of the patients were transported to a hospital for further diagnostics and treatment.

CONCLUSION

The prehospital intravenous administration of paracetamol by paramedics to patients with limb trauma is simple, safe and in 50 % of the patients effective in achieving a NRS value < 5; however, further improvements in prehospital pain therapy initiated by paramedics are desirable, especially in patients with an initial NRS value > 7.

Is there any advantage in placing an additional calcar screw in locked nailing of proximal humeral fractures?

BACKGROUND

The objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck.

HYPOTHESIS

The additional calcar screw improves stiffness and failure load.

METHODS

Fourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc(®)-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05).

RESULTS

No significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases.

DISCUSSION

The use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck.

Results of a phase I/II open-label, safety and efficacy trial of coagulation factor IX (recombinant), albumin fusion protein in haemophilia B patients

Introduction

rIX-FP is a coagulation factor IX (recombinant), albumin fusion protein with more than fivefold half-life prolongation over other standard factor IX (FIX) products available on the market.

Aim

This prospective phase II, open-label study evaluated the safety and efficacy of rIX-FP for the prevention of bleeding episodes during weekly prophylaxis and assessed the haemostatic efficacy for on-demand treatment of bleeding episodes in previously treated patients with haemophilia B.

Methods

The study consisted of a 10–14 day evaluation of rIX-FP pharmacokinetics (PK), and an 11 month safety and efficacy evaluation period with subjects receiving weekly prophylaxis treatment. Safety was evaluated by the occurrence of related adverse events, and immunogenic events, including development of inhibitors. Efficacy was evaluated by annualized spontaneous bleeding rate (AsBR), and the number of injections to achieve haemostasis.

Results

Seventeen subjects participated in the study, 13 received weekly prophylaxis and 4 received episodic treatment only. No inhibitors were detected in any subject. The mean and median AsBR were 1.25, and 1.13 respectively in the weekly prophylaxis arm. All bleeding episodes were treated with 1 or 2 injections of rIX-FP. Three prophylaxis subjects who were treated on demand prior to study entry had >85% reduction in AsBR compared to the bleeding rate prior to study entry.

Conclusion

This study demonstrated the efficacy for weekly routine prophylaxis of rIX-FP to prevent spontaneous bleeding episodes and for the treatment of bleeding episodes. In addition no safety issues were detected during the study and an improved PK profile was demonstrated.

[Suprapectoral mini-open biceps tenodesis - functional and sonographic results]

BACKGROUND

Aim of this study was to evaluate the effectiveness of a suprapectoral mini-open tenodesis of the long head of the biceps (LHB) tendon with ultrasound assessment. Secondary aim was to compare the results of an extraosseous fixation (group I) to those of an intraosseous fixation technique (group II).

PATIENTS AND METHODS

25 patients (10 female, 15 male) aged 54 ± 8 (36 to 68) years were followed-up 21 ± 4.7 (13 to 32) months postoperatively. Tenodesis fixation was extraosseous in 12 (group I) and intraosseous in 13 patients (group II). Preoperative shoulder function and intraoperative findings were recorded. At the time of follow-up the fixation of the biceps tendon was evaluated by ultrasound examination. Furthermore, the shoulder function, the simple shoulder test (SST), the Constant-Murley score (CMS) and the "long head of the biceps (LHB) score" were assessed.

RESULTS

Failure of tenodesis fixation was observed in 3/12 cases (25 %) of group I and 1/13 cases (8 %) of group II. Shoulder flexion (p < 0.001), abduction (p < 0.001), external rotation (p < 0.001) and the pain level (p < 0.001) improved significantly compared to the preoperative status. At time of follow-up the CMS averaged 79.4 ± 13 points, the age and gender related CMS averaged 95.7 ± 16.4 %. Mean SST was 10.6 ± 2.1 points. No significant difference (p = 0.064) could be observed between the LHB of the affected (88.1 ± 9.7) versus the non-affected shoulder (92.7 ± 13.6 points). Age and gender related CMS (p = 0.96), LHB score (p = 0.16) and SST (p = 0.94) of both groups revealed no significant differences.

CONCLUSION

The intraosseous fixation technique seems favourable with less fixation failure compared to the extraosseous suspension technique. The suprapectoral mini-open tenodesis of the LHB is a valuable alternative tenodesis technique with good to excellent clinical results.

[Corrective osteosynthesis of proximal humeral fractures. Technique and prospective results]

BACKGROUND

Fracture sequelae of proximal humeral fractures arise following nonoperative and operative forms of treatment. Due to a painful restricted range of motion, in most cases shoulder prostheses are implanted. There is a need for joint-preserving alternatives especially for younger patients.

OBJECTIVES

The aim of this study was to evaluate the surgical techniques and prospective results of fracture sequelae of proximal humeral fractures following corrective osteosynthesis.

MATERIAL AND METHODS

A total of 11 patients (4 female) with an average age of 53 years (range 29-71 years) and a mean follow-up of 19.5 months were included prospectively. The preoperative and postoperative ranges of motion of the affected shoulder were compared by statistical means. At the time of follow-up the constant score (CS), the simple shoulder test (SST) and the simple shoulder value (SSV) were assessed.

RESULTS

Fracture sequelae were classified as type II in four patients, as type III in two and as type IV in five patients using the Boileau classification. Shoulder flexion (p = 0.006), abduction (p = 0.003) and external rotation (p = 0.02) improved significantly in the postoperative course. The mean age and gender-adapted CS was 74.8 ± 19.9 % at the time of follow-up, 10.1 out of 12 points were reached in the SST and the mean SSV was 77 %.

CONCLUSION

Corrective osteosynthesis of fracture sequelae (Boileau types II-IV) of proximal humeral fractures appears to be a good alternative to implantation of shoulder prostheses, especially in younger patients (< 60 years of age).

[Unicentre Results in Surgery of Primary Hyperparathyroidism with Postoperative Long-Term Follow-Up and Value of Intraoperative Quick Parathormone Test]

BACKGROUND

The increasing use of focussed parathyroidectomy is attributed to introduction of intraoperative parathyroid hormone measurement (ioPTH) and novel preoperative imaging techniques. This study assesses the early postoperative and long-term outcomes of surgery and the value of standardised ioPTH in patients undergoing surgery for primary hyperparathyroidism (pHPT).

METHODS

From 01/01/1996 to 09/30/2011, all consecutive patients undergoing surgery for pHPT were documented. Data of this observational study were retrospectively evaluated. Patients were subdivided into 2 groups: A.) use of Quick Intraoperative Intact PTH Assay (n = 142; "ioPTH group") vs. B.) control group ("CG", n = 44). For clinical long-term follow-up, also pre- and postoperative signs, symptoms and findings of the initial 43 patients obtained during the first 4 years of the study were semiquantitatively compared.

RESULTS

186 consecutive operations for pHPT were performed - in particular, 73 sole parathyroidectomies; 113 combined thyroid and parathyroid resections. Mean operation time was 87 (SD ± 48) min for parathyroidectomy and 120 (SD ± 49) min for combined resections. A persisting hypercalcaemia was found in 16 patients (8.6%) while postoperative elevation of serum calcium and parathormone occurred in 7 patients (3.8%). Postoperative hypocalcaemia was present in 35 patients (18.8%). Differences between both groups regarding hypocalcaemia (p = 1.0), hypercalcaemia (p = 0.67), hyperparathyrinaemia (p = 0.12) and rate of reintervention (p = 0.055) were not significant. Thirty nine of the initial 43 patients reported one or more signs of pHPT (90.7%). Most frequent symptoms were nephrolithiasis (41.9%), back pain (51.2%), discomfort in the upper abdomen (41.9%), fatigue (41.9%) and general weakness (61.1%). Follow-up investigations (mean, 4.7 [range, 3.2-6.5] years) revealed that 65 % of patients reported improvement of general condition, 27% had no change and 8% reported deterioration.

CONCLUSIONS

IoPTH is now standard in parathyroid surgery. Value of ioPTH correlates directly with selected centre-specific intraoperative criteria. The stricter the criteria the more reliable is the exclusion of multiglandular disease. Surgery for pHPT was performed with a very low complication rate. Through the long-term follow-up, nearly two thirds of patients benefited from the operation.

[Applications of numerical simulation in musculoskeletal research and its impact on orthopedic surgery]

Finite element analyses (FEA) as well as multibody system dynamics (MSD) are the main tools used for numerical simulation in the field of musculoskeletal research. While FEA is utilized for field problems, such as calculation of stress and strain distribution, MSD is applied for solving kinematic analyses, such as calculation of muscle and joint forces. Depending on the focus of investigation, modelling of biological tissue may vary from simple homogeneous behavior to modelling biochemical processes on the microscale and nanoscale. An important milestone in biomechanical research was the analysis of stress shielding, which led to further research on bone remodelling. Various models of implant-bone fixation used for the prediction of micromotion have been published. New possibilities for biomechanical analyses are achieved by consideration of complex muscle forces which are generated by MSD simulation and imported into FEA models as limiting conditions. A numerical model always requires experimental validation. If the results are confirmed experimentally, various advantages of numerical simulation apply and problems can be analysed isolated from many influencing factors. Therefore, straightforward parameter variation is possible, enabling studies which would be impossible in an experimental or clinical setup.

Influence of rupture patterns of the medial patellofemoral ligament (MPFL) on the outcome after operative treatment of traumatic patellar dislocation

PURPOSE

Patellar dislocation usually occurs to the lateral side, leading to ruptures of the medial patellofemoral ligament (MPFL) in about 90 % of all cases. Reliable prognostic factors for the stability of the patellofemoral joint after MPFL surgery and satisfaction of the patient have not been established as yet.

METHODS

This multicentric study retrospectively included 40 patients with a mean age of 22.4 ± 8.1 years (range 9-48) from 5 German Trauma Departments with first-time traumatic patellar dislocation and operative treatment. Surgery was limited to soft tissue repairs, and a preoperative magnetic resonance imaging (MRI) was performed in all cases. Evaluation of the MRI included sulcus angle, dysplasia of the trochlea, depth and facet asymmetry of the trochlea, Insall-Salvati index, Tibial tuberosity to trochlear groove (TTTG) distance, and rupture patterns of the MPFL. Patients were interrogated after 2 years about recurrent dislocation, satisfaction, and the Kujala score.

RESULTS

Trochlea facet asymmetry was significantly lower in patients with redislocation (23.5 ± 18.8) than in patients without redislocation (43.1 ± 16.5, p = 0.03). Patients with a patellar-based rupture were significantly younger (19.5 ± 7.2 years) than patients without patellar-based rupture (25.4 ± 8.1 years, p < 0.02). Patients with femoral-based ruptures were significantly older (25.7 ± 9.2 years) than patients without femoral-based rupture (19.7 ± 6.1 years, p < 0.02), and had a significantly higher TTTG distance (10.2 ± 6.9 vs. 4.5 ± 5.5, p < 0.02). Patients with incomplete ruptures of the MPFL had a significantly lower Insall-Salvati index (1.2 ± 0.2 vs. 1.4 ± 0.2, p = 0.05). The Kujala score in patients with redislocations was significantly lower (81.0 ± 10.5 points) than in patients without redislocation (91.9 ± 9.2 points, p < 0.02).

CONCLUSION

Younger patients more often sustain patellar-based ruptures following first-time traumatic patella dislocation, while older patients more often sustain femoral-based ruptures of the MPFL. Incomplete MPFL ruptures are correlated with lower Insall-Salvati indices. Low trochlear facet asymmetry is correlated with higher rates of redislocation. These results may be of relevance for the operative and postoperative treatment in the future.

LEVEL OF EVIDENCE

Prognostic study, Level IV.

Operative vs conservative treatment of traumatic patellar dislocation: results of a prospective randomized controlled clinical trial

INTRODUCTION

Patellar dislocation is a common knee injury with mainly lateral dislocations, leading to ruptures of the medial patellofemoral ligament in most of the cases. Even though several prognostic factors for patellofemoral instability have been identified so far, the appropriate therapy for patients with patellar dislocation remains a controversial issue. The purpose of this study was to compare the outcome after conservative or operative treatment in patients after first-time patellar dislocation.

PATIENTS AND METHODS

This randomized controlled clinical trial was designed multicentric including patients from six German orthopaedic and trauma departments. Twenty patients with a mean age of 24.6 years with first-time traumatic patella dislocation were included and randomized into either a conservative arm or an operative arm. Plain X-ray images of the knee joint (a.p. and lateral view and tangential view of both patellae) were performed in all cases prior to therapy to exclude osteochondral fragments requiring refixation. An MRI was recommended, but not compulsory. Patients were consulted after 6, 12, and 24 months with a questionnaire including the criteria of the Kujala score, recurrent dislocation, and satisfaction.

RESULTS

The mean Kujala score of the conservative vs operative treatment group was 78.6 vs 80.3 after 6 months (p = 0.842), 79.9 vs 88.9 after 12 months (p = 0.165), and 81.3 vs 87.5 after 24 months (p = 0.339). Redislocation rate after 24 months was 37.5 % in the conservative group and 16.7 % in the operative group (p = 0.347). Due to the small number of patients that could be included, no significant difference between the groups could be detected. We see a tendency towards better results after operative treatment.

CONCLUSION

Our multicentric prospective randomized controlled trial revealed no significant difference between conservative and operative treatment for patients after first-time traumatic patellar dislocation. However, a tendency towards a better Kujala score and lower redislocation rates for patients with operative treatment was observed. The small number of patients is a limiting factor of the study, leading to results without statistical significance. A meta-analysis including other study's level I data is desirable for the future.

[Shoulder stiffness]

Primary shoulder stiffness is idiopathic. Due to coincidence with other diseases, a systemic genesis with hormonal influence is discussed. The result of chronic inflammation with fibroblastic proliferation is a fibrotic capsule, atrophy of ligaments, and muscular dysbalance. The main symptom is painful restricted passive and active shoulder motion. There is a high rate of unsatisfactory courses. Therapy depends on the phase and duration of shoulder stiffness. Primary treatment of choice is oral steroid therapy, followed by physical and physiotherapy. Steroids can be applied intraarticular, as an alternative. If conservative treatment fails after a period of 6 months, arthroscopic arthrolysis is indicated. Secondary shoulder stiffness often results from traumatization or operation of the shoulder. Primary treatment is also conservative, but operative intervention should be performed early after unsuccessful therapy. Intensive, passive mobilization is necessary after arthrolysis.

[Subscapularis tendon lesions. Anatomy, diagnosis and importance of arthroscopic treatment]

The subscapularis tendon is involved in up to 43% of arthroscopically treated rotator cuff lesions. Due to the close anatomic relationship, participation of the long head of the biceps and supraspinatus tendon is common. Subscapularis tendon lesions are often not primary diagnosed correctly. Using specific clinical tests and modern sectional imaging, the percentage of correct diagnoses can be increased. Convincing clinical results, advantages of minimally invasive surgery, and superior visualization compared to the open approach argue for arthroscopic treatment of subscapularis lesions. Awareness of the footprint allows anatomic reconstruction. In case of planned open treatment, arthroscopy should precede as particularly articular-sided lesions might be missed otherwise.

[Comparison of results after primary and secondary shoulder arthroplasty for proximal humeral fractures]

BACKGROUND

The purpose of this retrospective cohort study was to evaluate, compare and discuss the results and complications after primary and secondary shoulder arthoplasty in proximal humeral fractures.

PATIENTS AND METHODS

Thirteen consecutive patients (mean 76 years [range, 65-85] years) were at a mean of 29 (8-37) months after primary humeral head replacement (group 1), and 15 patients (mean 74 years [range, 43-80] years) at a mean of 18 (7-36) months after secondary shoulder arthoplasty (n = 8 anatomic prostheses, n = 7 reversed prostheses) due to complications/fracture sequelae (group 2) examined clinically and radiologically according to a standardised follow-up protocol. Patient satisfaction, the simple shoulder test (SST), the American shoulder elbow score (ASES) as well as the Constant score (CS) were assessed, and radiological parameters as well as complications analysed.

RESULTS

85 % of patients in group 1 and 73 % in group 2 were satisfied with the results. The SST did not show a significant difference between both groups. The adjusted ASES did not differ significantly with 70 (27-95)% in group 1 and 73 (28-100)% in group 2, as well as the adjusted CS with a mean of 53 (27-83)% in group 1 and of 49 (27-87)% in group 2. Radiological analysis resulted in a correctly centred prosthesis in 6/13 patients, and healed tuberosities in 7/13 of group 1. In group 2 4/8 anatomic prostheses were centered and 7/8 showed healed tuberosities. In the subgroup of the reversed prostheses 6/7 were centered, 3/7 patients had an inferior "notching". The rate of complications and revisions were 2/13 (15 %) in group 1 and 1/15 (7 %) in group 2.

CONCLUSION

In summary, the functional results did not differ significantly between primary and secondary shoulder arthroplasty after proximal humeral fractures. The relatively low expectation of elderly patients is reflected in a high rate of patient satisfaction in spite of moderate functional results. The primary humeral head replacement showed higher rates of complications and revisions compared to secondary arthroplasty.

[How to become a trauma surgeon: analysis of the current situation and concepts for career development in the new common field of orthopaedics and trauma surgery--part I]

The lack of clinical residents especially in the surgical domains, including orthopaedics and trauma surgery, is not only omnipresent but also a topic of lively discussions. This lack originates from sociopolitical and healthcare policy issues as well as from a loss of attractiveness of all surgical disciplines. The loss is caused by the high workload and disadvantageous working hours especially in those disciplines with a high rate of emergencies, e.g. trauma surgery. Moreover, it is caused by the poorly structured and unpredictable period of residency. In order to anticipate the bottleneck in supply due to the lack of trainees, a number of structural and contextual measures have to be taken to improve both undergraduate und postgraduate surgical training. Due to the numerous facets of the topic the first part of this analysis refers to the period until the trainee decides on the field of training.A basic insight into the field of orthopaedics and trauma surgery can already be offered far before the period of medical studies itself. During undergraduate medical education the existing structures should be modified, the characteristics of the discipline should be emphasized and the charm of combining theory and practical skills should be highlighted in order to enhance student's perception of the discipline. This might begin during preclinical training and should be continued throughout clinical training and elective courses (basic wound care, TEAM approach, AO course for students and seminars for M.D. candidates). Contextual and structural improvements of the practical year are indispensable to arouse students' interest in our discipline. These options conjoined with the actual offers for students provided by our scientific society, such as guided tours during the annual congress, travelling grants and the recently inaugurated summer school, might provide the basis for clearly structured information and offer a distinct stimulus to apply for residency in our field.

[Early functional treatment and full weight-bearing of surgically treated isolated ankle fractures in the elderly]

QUESTION

Fractures of the ankle joint belong to the most often occurring injuries. The aftercare in plaster lasts several weeks and is problematic especially in elderly patients.

METHODS

In a retrospective study patients over the age of 50 years who underwent surgical treatment of ankle fractures and early functional mobilization were examined in a follow-up. The range of motion, the circumferential measurements and the radiological course were examined by comparing preoperative and postoperative X-ray images after 13-24 months. The subjective results were collected using the Olerud-Molander score (OMS).

RESULTS

A total of 30 out of 42 patients who qualified for the follow-up were included in the study. The distribution of the gender was equal as was the right/left distribution and the mean age was 68 years. The magnitude of movement and comparison between the two sides showed no significant differences. The average score for subjective satisfaction was 90 in the OMS. The radiological results showed few changes and no deviations from the axis. No redislocations or implant fractures could be observed. Early functional full weight-bearing showed satisfactory preliminary results.

CONCLUSION

This treatment concept can be recommended because patient comfort is increased and the risk of immobilization is excluded.

[Proximal humeral fracture]

Fractures of the proximal humerus are very common in elderly people with an increasing incidence. Complex fracture-patterns are observed. For radiological examination x-rays in 2 planes are mandatory. Often an additive CT-scan can be useful for a better understanding of the whole fracture-character. Limits of accepted fracture displacement decrease and reconstructive surgery is induced more frequently. Advantageous are the functional after-treatment and the early reintegration to the activities of daily living after osteosyntheses. Locking nail- and platesystems are competing standard-implants, whereas plate osteosynthesis is preferred in higher-part-fractures. Non-reconstructable fractures should be treated with a primary head replacement, in the form of a reverse prosthesis in patients older than 75 years.

Open reduction and internal fixation of proximal humeral fractures with use of the locking proximal humerus plate. Surgical technique

BACKGROUND

The treatment of unstable displaced proximal humeral fractures, especially in the elderly, remains controversial. The objective of the present prospective, multicenter, observational study was to evaluate the functional outcome and the complication rate after open reduction and internal fixation of proximal humeral fractures with use of a locking proximal humeral plate.

METHODS

One hundred and eighty-seven patients (mean age, 62.9 +/- 15.7 years) with an acute proximal humeral fracture were managed with open reduction and internal fixation with a locking proximal humeral plate. At the three-month, six month,and one-year follow-up examinations, 165 (88%), 158 (84%), and 155 (83%) of the 187 patients were assessed with regard to pain, shoulder mobility, and strength. The Constant score was determined at each interval, and the Disabilities of the Arm, Shoulder and Hand (DASH) score was determined for the injured and contralateral extremities at the time of the one-year follow-up.

RESULTS

Between three months and one year, the mean range of motion and the mean Constant score for the injured shoulders improved substantially. Twelve months after surgery, the mean Constant score for the injured side was 70.6 +/- 13.7 points, corresponding to 85.1% +/- 14.0% of the score for the contralateral side. The mean DASH score at the time of the one-year follow-up was 15.2 +/- 16.8 points. Sixty-two complications were encountered in fifty-two (34%) of 155 patients at the time of the one-year follow-up. Twenty-five complications (40%) were related to incorrect surgical technique and were present at the end of the operative procedure. The most common complication, noted in twenty-one (14%) of 155 patients, was intraoperative screw perforation of the humeral head. Twenty-nine patients (19%) had an unplanned second operation within twelve months after the fracture.

CONCLUSIONS

Surgical treatment of displaced proximal humeral fractures with use of the locking proximal humeral plate that was evaluated in the present study can lead to a good functional outcome provided that the correct surgical technique is used. Because many of the complications were related to incorrect surgical technique, it behooves the treating surgeon to perform the operation correctly to avoid iatrogenic errors.

Hook plate for medial clavicle fracture

Medial clavicle fractures are the least common type of clavicular fractures. Although rare, such injuries deserve rapid diagnosis and effective treatment to avoid future complications. An optimal, standardized operative treatment has not been yet established. We report a case of medial clavicle fracture, where primary operative treatment was indicated due to gross dislocation. An open reduction and osteosynthesis with a modified hook plate was performed, leading to an excellent postoperative outcome after a sixteen-month follow-up. The hook plate seems to be a promising approach for the operative treatment of medial clavicle fractures.

Arthroscopic treatment of multidirectional glenohumeral instability in young overhead athletes

Purpose:

This prospective case series evaluates the outcome, and the return to sports of young overhead athletes with a persistent, symptomatic multidirectional instability (MDI) with hyperlaxity type Gerber B5 treated with an arthroscopic anteroposteroinferior capsular plication and rotator interval closure.

Methods:

9 young overhead athletes (10 shoulders) with the rare diagnosis of MDI (Gerber B5) and an indication for operative treatment, after a failed physiotherapy program were physically examined 3, 6 and 12 months postoperatively by a physical examination, and got a final phone interview after median 39 months.

Results:

At the final follow-up all patients were satisfied; Rowe Score showed 7 “excellent” and “good” results; Constant Score was “excellent” and “good” in 6, and “fair” in 1 patient. 7/9 returned to their previous sports, 3/9 at a reduced level.

Conclusion:

Symptomatic MDI requires an individual indication for surgical treatment after a primary conservative treatment. The described arthroscopic technique stabilizes glenohumeral joint. A return to overhead sports is possible but often at a reduced level; returning to high-performance sports cannot be recommended because of the high risk of reinstability.

[Single bundle anterior cruciate ligament reconstruction using quadriceps tendon autografts]

AIM

The purpose of this study was to evaluate postoperative outcome and functional scores after single bundle anterior cruciate ligament (ACL) reconstruction with the use of quadriceps tendon autografts after a 16 (12-24) month follow-up.

METHOD

54 patients (9 women, 45 men, body mass index [BMI] 25.3 [18.1-36.3 kg/m (2)]) were included in this prospective series, treated between January 2004 and December 2005. Ligament stability was assessed with the Lachmann and pivot-shift tests and a KT 1000 arthrometer. Tegner index, Lysholm-Gilquist score and the International Knee Documentation Committee (IKDC) were employed to evaluate the functional outcomes. In addition, the single leg hop test was performed.

RESULTS

Ligament arthrometry using the KT 1000 arthrometer demonstrated a mean side-to-side difference of 1.53 mm (0.2-4.1 mm). Regarding the Lachmann test, 17 patients (32%) showed 1+ laxity and no patient had an abnormal pivot-shift. The mean Tegner activity score was 4.22 (1-10), the mean Lysholm score was 80.8 (20-100) and the mean IKDC score 68.1 (29-87). Results of the single leg hop test revealed a mean decline of the treated leg to 87.7% (70-100%) of the contralateral side. The mean extension was reduced by 1.7 degrees (0-10 degrees) on the treated knee and the flexion by 2.1 degrees (0-10 degrees), compared to the contralateral knee.

CONCLUSION

Single bundle anterior cruciate ligament reconstruction using quadriceps tendon demonstrates highly satisfactory results. Due to a moderate donor site morbidity and preservation of the medial stabilizing structures of the knee a wider use in primary cruciate ligament reconstruction may arise in the future.