Implications of navigation in thoracolumbar pedicle screw placement on screw accuracy and screw diameter/pedicle width ratio

Introduction

There is ample evidence that higher accuracy can be achieved in thoracolumbar pedicle screw placement by using spinal navigation. Still, to date, the evidence regarding the influence of the use of navigation on the screw diameter to pedicle width ratio remains limited.

Research question

The aim of this study was to investigate the implications of navigation in thoracolumbar pedicle screw placement not only on screw accuracy, but on the screw diameter to pedicle width ratio as well.

Material and methods

In this single-center single-surgeon study, 45 Patients undergoing navigated thoracolumbar pedicle screw placement were prospectively included. The results were compared with a matched comparison group of patients in which screw placement was performed under fluoroscopic guidance. The screw accuracy and the screw diameter to pedicle width ratio of every screw were compared between the groups.

Results

Screw accuracy was significantly higher in the navigation group compared to the fluoroscopic guidance group, alongside with a significant increase of the screw diameter to pedicle width ratio by approximately 10%. In addition, both the intraoperative radiation dose and the operating time tended to be lower in the study group.

Conclusion

This study was able to show that navigated thoracolumbar pedicle screw placement not only increases the accuracy of screw placement but also facilitates the selection of the adequate screw sizes, which according to the literature has positive effects on fixation strength. Meanwhile, the use of navigation did not negatively affect the time needed for surgery or the patient's intraoperative exposure to radiation.

Revision lateralization osteotomy of the tibial tubercle has excellent outcomes in patients suffering from previous medial tibial tubercle overcorrection

INTRODUCTION

Tibial tubercle osteotomy (TTO) is a common procedure used to treat patients with patellofemoral instability (PFI) and osteoarthritis (PFOA). Medial patellar maltracking due to previous excessive medialization of the tibial tubercle has rarely been reported. Therefore, the goal of this study was to assess patient-reported outcome measures (PROMs) after revision osteotomy with lateralization of the tibial tubercle (RL-TTO) to correct medial patellofemoral maltracking.

MATERIALS AND METHODS

Between 2017 and 2021, a series of 11 patients (male/female 1/10; age 35.8 ± 10.5 years) were treated by RL-TTO, of whom 8 patients could be retrospectively evaluated after a mean of 32.4 ± 15.1 months (range 18-61 months) postoperatively. The Kujala anterior knee pain scale, the patellofemoral subscale of the Knee Osteoarthritis and Outcome Score (KOOS-PF), and a numeric analog scale (NAS; 0-10) regarding anterior knee pain (AKP) at rest and during activity were assessed from pre- to postoperatively.

RESULTS

The preoperative mean tibial tubercle-trochlear groove (TT-TG) and tibial tubercle-posterior cruciate ligament (TT-PCL) distances were - 6.5 ± 6.5 mm and 0.7 ± 4.6 mm, respectively. The intraoperatively determined amount of tibial tubercle lateralization averaged 10.7 ± 3.6 mm. The Kujala score and KOOS-PF improved significantly from 33.6 ± 10.1 (23-51) points to 94.4 ± 6.2 points (82-100) (p < 0.001) and from 20.6 ± 13.2 points (0-43.3) to 87.3 ± 9.9 points (72.8-100) (p < 0.001) from pre- to postoperatively, respectively. Pain at rest decreased from 5.8 ± 1.9 to 0.8 ± 0.9 (p < 0.001), and pain during activity decreased from 8.6 ± 1.3 to 1.6 ± 1.5 (p < 0.001).

CONCLUSION

RL-TTO significantly improved subjective knee function and AKP in patients suffering from medial patellar maltracking due to previous excessive tibial tubercle medialization osteotomy at short-term follow-up.

Patients older than 55 years regain sporting and recreational activities after arthroscopic anterior cruciate ligament reconstruction

PURPOSE

(1) To compare sporting and recreational activity levels before and at a minimum 6 year follow-up, and (2) to assess the clinical and functional outcomes after anterior cruciate ligament (ACL) reconstruction in patients older than 55 years.

METHODS

A retrospective evaluation of prospectively collected data of 150 patients with a mean age of 64 ± 4.5 (57-74) years was evaluated 8.6 ± 1.4 (6-11) years after primary ACL reconstruction using hamstring autograft. All patients were assessed using the International Knee Documentation Committee scoring system (IKDC), Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner activity level, and visual analog scale (VAS) for pain. The level of recreational activities was assessed using a sport-specific questionnaire. All patients were categorized according to Isolated and Combined ACL injury groups.

RESULTS

The data of 125 patients were analyzed at the last follow-up. While 25 patients were lost to follow-up, 117 of 125 patients were active before their injury in at least one sports discipline compared to 121 of 125 patients after ACL reconstruction. One hundred and two (82%) patients had returned to their recreational activities at the final follow-up. The mean IKDC subjective score increased from 49.5 ± 23.2 (11.5-100) to 76.2 ± 14.8 (33.3-100) (p < 0.0001). The mean KOOS sport increased significantly from 36 ± 36.2 (0-100) to 74.1 ± 25.5 (0-100) (p < 0.0001). The mean VAS score improved from 6.0 ± 2.6 (0-10) to 1.0 ± 1.4 (0-6) (p < 0.0001). There was no significant difference in the median Tegner activity level (preoperative 5 (2-8) vs. follow-up 5 (2-8) (n.s). There was no significant difference in the number of sports disciplines and duration when comparing pre-injury and mid-term follow-up activity after ACL reconstruction. High-impact activities experienced a significant decline, while a significant increase in participation in low-impact activities was recorded.

CONCLUSION

The majority of patients with symptomatic instability regained their pre-injury recreational activity level with excellent clinical and functional outcomes after arthroscopic ACL reconstruction. Nevertheless, a change from high-to low-impact activities has been observed.

LEVEL OF EVIDENCE

Level IV.

When Should Bony Correction Be Considered in Addition to Medial Patellofemoral Ligament Reconstruction? Results of a Clinically Derived 2-Group Classification of Lateral Patellar Instability Based on 122 Patients at 2- to 5-Year Follow-up

Background

The need for concomitant bony procedures to realign pathoanatomic risk factors in addition to medial patellofemoral ligament reconstruction (MPFL-R) remains unclear.

Purpose

To evaluate a clinically derived 2-part classification of lateral patellar instability aimed at identifying patients indicated for a concomitant bony procedure.

Study Design

Cohort study; Level of evidence, 3.

Methods

The study included 122 patients (42 male, 80 female; mean ± SD age, 22 ± 6 years) who were assigned to a mild instability group (mIG) and a complex instability group (cIG) based on the reversed dynamic patellar apprehension test (ReDPAT) and J-sign. The mIG had a positive ReDPAT result <40° to 50° of knee flexion and an absent or low-grade J-sign (grade 1), and the cIG had a positive ReDPAT result >40° of knee flexion and/or a high-grade J-sign (grade 2 or 3). The mIG underwent isolated MPFL-R, and the cIG underwent MPFL-R and concomitant bony procedures depending on the established risk factor assessment. For evaluation, the BANFF Patellar Instability Instrument 2.0 (BPII 2.0) and numeric analog scale (0-10) for patellofemoral pain and subjective knee function were used. The minimal clinically important difference for the BPII 2.0 was ascertained by calculating half the standard deviation of baseline scores.

Results

Radiographic analysis confirmed a significantly more pronounced pathoanatomic risk factor constellation in the cIG regarding severity of trochlear dysplasia, distal malalignment, and patellar height (all P < .05). At final follow-up, no patellar redislocation occurred in either group; 2 patients in the cIG reported patellar subluxation. Within both groups, all outcome scores improved significantly pre- to postoperatively (all P < .0001); no between-group difference was found regarding BPII 2.0 score and numeric analog scale for function. The minimal clinically important difference for the BPII 2.0 was met by 84% (32/38) of the mIG and 90% (76/84) of the cIG (P = .36), but the cIG experienced more patellofemoral pain than the mIG (1.3 ± 1.6 vs 2.1 ± 2.1; P = .036).

Conclusion

Patients with a high-grade J-sign and/or a positive ReDPAT finding beyond 40° to 50° of knee flexion exhibited a significantly more pronounced pathoanatomic risk factor constellation; however, the correction of modifiable risk factors led to similarly good outcomes to patients who underwent isolated MPFL-R. A slightly higher level of patellofemoral pain after bony procedures was evident in these patients.

[Computer-assisted procedures in orthopedics and trauma surgery-Where do we stand?]

Computer-assisted procedures are becoming increasingly more relevant in orthopedics and trauma surgery. The data situation on these systems has improved in recent years but still has a low level of evidence. In particular, data on short-term or medium-term results on the use of these procedures are currently available. These could show that improved precision and reproducibility of the surgical procedures can be achieved by the use of computer-assisted procedures. Nevertheless, there is still no recommendation in the current guidelines for routine use.

Medial patellofemoral ligament reconstruction using nonresorbable sutures yields comparable outcomes to reconstruction with a pedicled quadriceps tendon autograft when performed in addition to bony risk factor correction

PURPOSE

To evaluate the results for reconstruction of the medial patellofemoral ligament using synthetic nonresorbable sutures (S-MPFL-R) in comparison to MPFL-R using quadriceps tendon autograft (QT-MPFL-R) in patients undergoing simultaneous correction of anatomic risk factors for lateral patellar instability (LPI) at a minimum of 2 years of follow-up.

METHODS

Between November 2018 and June 2019, 19 patients (male/female 8/11; mean age 26 ± 7 years) underwent S-MPFL-R (FiberTape^®) in combination with the correction of predisposing risk factors for LPI. The control group of 38 patients (male/female 16/22, mean age 26 ± 6 years) who underwent QT-MPFL-R was matched 1:2 by sex, age, anatomic risk factors, and concomitant surgical correction of bony risk factors. The Banff Patella Instability Instrument 2.0 (BPII 2.0) and a numerical analog scale (NAS 0-10) for patellofemoral pain and subjective knee joint function were used to assess patients' reported quality of life before and after surgery.

RESULTS

The BPII 2.0 score increased from 35.0 ± 21.7 points to 79.7 ± 13.3 points (p < 0.0001) in the S-MPRL-R group and from 44.3 ± 19.6 points to 80.9 ± 15 points (p < 0.0001) in the QT-MPFL-R group from preoperatively to postoperatively, respectively, without any significant difference between the groups. In the S-MPFL-R group and QT-MPFL-R group, 95% (18/19) and 92% (35/38) of patients, respectively, crossed the minimally clinically important difference reported for the BPII 2.0. NAS values for pain and subjective knee joint function improved significantly in both groups (p < 0.0001, p < 0.0001) without any significant difference between the groups at the final follow-up.

CONCLUSIONS

This study demonstrates that nonresorbable sutures can serve as a viable option for MPFL-R, yielding comparable outcomes compared to quadriceps tendon autograft reconstruction when performed concomitantly with the correction of anatomic risk factors for LPI. This option reduces the need for autologous tendon harvesting or the use of allografts for MPFL-R.

LEVEL OF EVIDENCE

Level III.

Is the postoperative pedicle screw position after dorsal instrumentation with or without intraoperative cone beam CT imaging worse in patients with obesity than in normal-weight patients?

Background

Intraoperative cone beam CT (CBCT) imaging in dorsal instrumentation facilitates pedicle screw positioning. However, in patients with obesity, the benefit may be reduced due to artifacts that affect image quality. The purpose of this study was to evaluate whether intraoperative CBCT leads to an improved postoperative screw position compared to conventional fluoroscopy independent of body weight.

Methods

A total of 71 patients (18 patients with a BMI > 30 kg/m², 53 patients with a BMI < 30 kg/m²) who underwent dorsal instrumentation with intraoperative CBCT imaging were included in study groups one (SG1) and two (SG2). Two control groups (CG1 and CG2) were randomly sampled to include 22 patients with a BMI > 30 kg/m² and 60 patients with a BMI < 30 kg/m² who underwent dorsal instrumentation without intraoperative CBCT imaging. The pedicle screw position in postoperative computed tomography was assessed using the Gertzbein–Robbins classification.

Results

In SG1 (BMI > 30 kg/m²), a total of 107 (83.6%) pedicle screws showed no relevant perforation (type A + B), and 21 (16.4%) pedicle screws showed relevant perforation (type C − E). In SG2 (BMI < 30 kg/m²), 328 (90.9%) screws were classified as type A + B, and 33 (9.1%) screws were classified as type C − E. In CG1 (BMI > 30 kg/m²), 102 (76.1%) pedicle screws showed no relevant perforation (type A + B), and 32 (23.9%) pedicle screws showed relevant perforation (type C − E). In CG2 (BMI < 30 kg/m²), 279 (76.9%) screws were classified as type A + B, and 84 (23.1%) screws were classified as type C − E. There were significant differences between the values of SG1 and SG2 (p = 0.03) and between the values of SG2 and CG2 (p < 0.0001).

Conclusion

CBCT imaging in dorsal instrumentation can lead to an improved pedicle screw position among both patients with obesity and normal-weight patients. However, patients with obesity showed significantly worse pedicle screw positions postoperatively after dorsal instrumentation with intraoperative CBCT imaging than normal-weight patients.

Combined distal femoral osteotomy and tibial tuberosity distalization is effective in patients presenting with patellar instability and patellofemoral pain due to patella alta and femoral malalignment

INTRODUCTION

Patellar malalignment has been considered one of the major pathomechanical causes of patellofemoral instability and pain. The results have been reported after femoral varization/torsional osteotomy and tibial tuberosity distalization osteotomy (TTD-O). However, the combination of a femoral deformity (genu valgum/increased femur antetorsion) and patella alta remains underreported. Therefore, the aim of this study was to investigate the clinical outcomes of patients simultaneously treated by distal femoral osteotomy and TTD-O. The hypothesis was that restoration of patellofemoral (PF) alignment via the abovementioned osteotomies would achieve good patient-reported outcome measures.

MATERIALS AND METHODS

Between 2016 and 2019, a series of 25 knees in 20 patients were treated by a distal femoral osteotomy combined with a TTD-O aiming to correct patellofemoral malalignment consisting of genu valgum and/or increased femur antetorsion and patella alta. Six patients were lost to follow-up, and one patient refused to participate. Thus, 17 knees in 13 patients (male/female 1/12; age 27.4 ± 5.4 years) were included and comprised the study group for this investigation. Patients were evaluated after a mean of 3.1 ± 0.9 years postoperatively. The Kujala anterior knee pain scale and the PF-subscale of the Knee Osteoarthritis and Outcome score (KOOS-PF) were used to assess patients' reported outcome measures from pre- to postoperatively.

RESULTS

The mean amount of torsional correction, valgus correction, and tibial tuberosity distalization averaged 14° (10°-18°), 5.2° (3.8°-8°), and 9 mm (6°-15 mm), respectively. The Kujala score increased by an average of 24.18 points from a mean of 66.6 ± 18.3 points (34-93 points) preoperatively to 90.8 ± 14.2 points (44-100 points) postoperatively (95% CI - 33.0 to - 15.3; p < 0.0001). The KOOS-PF score increased by an average of 33.7 points from a mean of 49.5 ± 24.5 points (9.1-88.6 points) preoperatively to 83.2 ± 21.6 points (15.9 -100 points) postoperatively (95% CI - 47.5 to - 19.9; p < 0.0001).

CONCLUSION

The findings of this study indicate that the combination of a distal femoral osteotomy and a tibial tuberosity distalization osteotomy is effective in patients presenting with patellar instability and patellofemoral pain due to patella alta and femoral malalignment.

Mental and physical health-related quality of life in patients with recurrent patellar dislocations-a generic and disease-specific quality of life questionnaire assessment

Purpose

There is a paucity of quality of life (QoL) assessments in studies evaluating patients treated for recurrent lateral patellar dislocation (LPD). The primary aim of this study was to investigate whether mental well-being is impaired in patients with chronic (recurrent) LPD and, if so, to assess whether the mental health-related QoL dimension improves equivalently to the physical-related QoL dimension after successful surgical treatment.

Methods

Thirty-eight patients with recurrent LPD over a mean course of the disease of 4.7 ± 3.9 years (1—18 years) prior to surgery were included. Generic health-related QoL (HRQoL) (Short Form 36; SF-36) and disease-specific QoL (Banff Patella Instability Instrument 2.0; BPII 2.0) were assessed preoperatively and after a mean follow-up of 3.5 ± 0.8 years (2 – 5 years) postoperatively.

Results

Untreated LPD significantly impacted the physical dimension of patients’ generic HRQoL and their disease-specific QoL. When compared to age-equivalent normative data sets, the mental HRQoL dimension was not reduced prior to operative treatment but increased during the follow-up period. Surgical treatment normalized the physical dimension of patients’ generic HRQoL and significantly improved their disease-specific QoL. However, BPII 2.0 values remained reduced, albeit patellae were successfully stabilized.

Conclusion

The results of this study indicate that patients with recurrent LPD are generally in good mental health, although physical impairment is striking. Notwithstanding that surgery prevented further dislocations and normalized the generic HRQoL, the disease-specific QoL remained reduced as far as this can be interpreted without population-based data.

Level of evidence

Level IV; Retrospective case series.

Revision surgery for failed medial patellofemoral ligament reconstruction results in better disease-specific outcome scores when performed for recurrent instability than for patellofemoral pain or limited range of motion

PURPOSE

Medial patellofemoral ligament reconstruction (MPFL-R) is an important treatment for recurrent patellar instability. Although complications such as redislocation, patellofemoral pain (PFP) and restricted knee range of motion have been reported, few studies have investigated the results of revision surgery for failed MPFL-R. Thus, the aim of this study was to determine the results of the tailored revision surgery after considering the cause of the reconstruction failure.

MATERIALS AND METHODS

Between 2015 and 2019, 28 patients (male/female 9/19; age 26.2 ± 6.4 years) underwent revision surgery for failed MPFL-R. The patients were grouped into the "recurrent instability" (SG1) group and "PFP" and/or "restricted range of motion" (SG2) group. Preoperatively, the clinical data, anatomical risk factor profile, and position of the femoral MPFL tunnel were determined for each patient. The Banff Patella Instability Instrument 2.0 (BPII 2.0) and numerical analogue scale (NAS 0-10) were administered preoperatively and at the final follow-up for the subjective assessment of the PFP and knee joint function.

RESULTS

Overall, the BPII 2.0 score improved from 28.8 ± 16.6 points preoperatively to 68.0 ± 22.7 points (p < 0.0001) postoperatively. SG1 exhibited an increase in the BPII 2.0 score from 28.9 ± 20.2 points to 75.7 ± 23 points (p < 0.0001). PFP decreased from 6.8 ± 2.4 to 1.6 ± 1.9 (p < 0.0001), while the knee joint function increased from 4.3 ± 2.5 to 8.8 ± 1.6 (p < 0.0001). In SG2, the BPII 2.0 score increased from 28.7 ± 12.6 points preoperatively to 57.7 ± 19.7 points (p = 0.0002) postoperatively and was thus significantly lower than that in SG1 (p = 0.038). The intensity of PFP decreased from 6.6 ± 3.0 preoperatively to 2.1 ± 1.9 postoperatively (p = 0.0006), while the subjective knee joint function improved from 3.2 ± 1.4 preoperatively to 7.6 ± 2.3 postoperatively (p < 0.0001). The differences between the groups were not significant.

CONCLUSION

Tailored revision surgery for failed MPFL-R significantly improves the patient-reported disease-specific quality of life. The study results indicate that patients undergoing revision surgery as a consequence of patellar redislocation appear to benefit more from revision surgery than those patients undergoing revision due to postoperative PFP and/or a limited knee joint range of motion.

LEVEL OF EVIDENCE

Level IV.

The J-sign and the body mass index determine the disease-specific quality of life in patients with lateral patellar instability

PURPOSE

To determine which risk factors for patellar instability contribute most relevantly to patients' subjective disease-specific quality of life, aiming to provide implications on the overall treatment decision-making process.

METHODS

A total of 182 consecutive patients (male/female 70/112; mean age 23.6 ± 7.3 years) with a history of patellar instability were prospectively enrolled in this study. Patient age, body mass index (BMI), number of dislocations, reversed dynamic patellar apprehension test (ReDPAT), J-sign severity, and pathoanatomic risk factors of patellar instability were assessed. The statistical analysis evaluated the relationships among those variables and determined their ability to predict the Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) as a disease-specific quality of life measure. Using Spearman correlation, ANOVA and Fisher's exact test, all variables with ANOVA p ≤ 0.1 or Spearman's abs (rho) > 0.1 were entered into a multivariate linear model using backward-stepwise selection.

RESULTS

Analysis of the individual variables' ability to predict BPII 2.0 score values revealed 'age', 'BMI', 'ReDPAT', 'high grade of trochlear dysplasia', and 'high-grade J-Sign' as possible relevant factors. Backward-stepwise multivariate regression analysis yielded a final parsimonious model that included the factors 'BMI' and 'J-Sign (Grade II and III)' as the most relevant parameters influencing BPII 2.0 score values (adjusted R² = 0.418; p < 0.001), with a cutoff value for BMI found at 28 kg/m² (p = 0.01).

CONCLUSION

The results of this study indicate that in patients with lateral patellar instability, a high-grade J-sign and an increased BMI significantly impact subjective disease-specific quality of life.

LEVEL OF EVIDENCE

Level IV.

Return to Sports and Patients' Rehabilitation Continuum After Deepening Trochleoplasty and Concomitant Patellar-Stabilizing Procedures: A Case Series of 111 Patients at 2 to 4 Years of Follow-up

BACKGROUND

There are few reports on the return to sports after complex patellar-stabilizing surgery.

PURPOSES

To evaluate patients' ability to return to sports and to investigate the extent to which the preoperative level of sports participation influences sports activity after deepening trochleoplasty (TP) and concomitant patellar-stabilizing procedures.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between April 2015 and April 2019, 144 patellar-stabilizing procedures, including deepening TP and medial patellofemoral ligament reconstruction or medial reefing with and without concomitant realignment procedures, were carried out in 142 patients. The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) and the Tegner activity score were used to assess patients' quality of life and sports activity level. In addition, a numerical analog scale was used to evaluate patellofemoral pain intensity during rest and activity and subjective knee joint function.

RESULTS

Outcomes were available for 111 patients (112 knees) (male/female, 77/34; mean age, 23.4 ± 7.8 years), yielding a 77.7% follow-up rate at a mean of 39.2 ± 9.9 months (range, 24-48 months). Two-thirds of the patients returned to their preoperative level of activity or higher, but their Tegner scores did not change significantly (4.5 ± 2.4 vs 4.7 ± 1.6; P = .365). Low-level athletes (preoperative Tegner score 0-4) participated at a higher level of sports activity (2.7 ± 1.4 to 4.1 ± 1.2; P < .0001), whereas higher-level athletes (preoperative Tegner score 5-10) participated at a lower level (6.8 ± 1.3 to 5.5 ± 1.7; P < .0001). The likelihood of returning to the preoperative activity level (Tegner score) was significantly higher in the low-level activity group than in the high-level activity group (P = .0001; 95% CI, 4.055-27.05; odds ratio, 10.47). All of the patient-reported outcome measures improved postoperatively, independent of the patients' age, sex, and body mass index.

CONCLUSION

Patients undergoing deepening TP and medial soft tissue stabilization with or without concomitant realignment surgery for complex patellar instability can expect good clinical results and a high rate of return to sports participation, with two-thirds of patients returning to their preoperative Tegner-level of activity or higher. However, higher-level athletes should be informed that their likelihood of returning to sports at the preoperative level or full participation at a competitive level is reduced.

Intraoperative 3D imaging with cone-beam computed tomography leads to revision of pedicle screws in dorsal instrumentation: a retrospective analysis

Background

Correct positioning of pedicle screws can be challenging. Intraoperative imaging may be helpful. The purpose of this study was to evaluate the use of intraoperative 3D imaging with a cone-beam CT. The hypotheses were that intraoperative 3D imaging (1) will lead to an intraoperative revision of pedicle screws and (2) may diminish the rate of perforated screws on postoperative imaging.

Methods

Totally, 351 patients (age 60.9 ± 20.3 a (15–96); m/f 203/148) underwent dorsal instrumentation with intraoperative 3D imaging with 2215 pedicle screws at a trauma center level one. This study first evaluates intraoperative imaging. After this, 501 screws in 73 patients (age 62.5 ± 19.7 a; m/f 47/26) of this collective were included in the study group (SG) and their postoperative computed tomography was evaluated with regard to screw position. Then, 500 screws in 82 patients (age 64.8 ± 14.4 a; m/f 51/31) as control group (CG), who received the screws with conventional 2D fluoroscopy but without 3D imaging, were evaluated with regard to screw position.

Results

During the placement of the 2215 pedicle screws, 158 (7.0%) intraoperative revisions occurred as a result of 3D imaging. Postoperative computed tomography of the SG showed 445 (88.8%) screws without relevant perforation (type A + B), of which 410 (81.8%) could be classified as type A and 35 (7.0%) could be classified as type B. Fifty-six (11.2%) screws in SG showed relevant perforation (type C–E). In contrast, 384 (76.8%) screws in the CG were without relevant perforation (type A + B), of which 282 (56.4%) could be classified as type A and 102 (20.4%) as type B. One hundred and sixteen (23.2%) screws in the CG showed relevant perforation (type C–E).

Conclusion

This study shows that correct placement of pedicle screws in spine surgery with conventional 2D fluoroscopy is challenging. Misplacement of screws cannot always be prevented. Intraoperative 3D imaging with a CBCT can be helpful to detect and revise misplaced pedicle screws intraoperatively. The use of intraoperative 3D imaging will probably minimize the number of revision procedures due to perforating pedicle screws.

Outcomes After Deepening Trochleoplasty and Concomitant Realignment in Patients With Severe Trochlear Dysplasia With Chronic Patellofemoral Pain: Results at 2-Year Follow-up

Background

Abnormal patellofemoral joint stress appears to have major relevance in a subgroup of patients with patellofemoral pain (PFP).

Purpose

To evaluate whether patients with chronic PFP and trochlear dysplasia-induced patellofemoral joint malalignment benefit from a deepening trochleoplasty procedure with the aim of improving patellotrochlear congruence.

Study Design

Case series; Level of evidence, 4.

Methods

Included were 15 patients (male/female, 1/14; mean age, 30.3 years [range, 19-51 years]) with 8.8 years (range, 1-20 years) of chronic PFP and severe trochlear dysplasia. All patients underwent correction of patellotrochlear malalignment with deepening trochleoplasty and concomitant realignment procedures. The Kujala score and a numerical analog scale (0-10) for intensity of pain were used to assess symptoms preoperatively and at 12 and 24 months postoperatively. Pre- and postoperative magnetic resonance imaging (MRI) scans from the patients were compared with the MRI scans of age- and sex-matched controls regarding the patellotrochlear contact area and contact ratio, patellar tilt, patellotrochlear index, and lateral trochlear inclination (LTI) angle.

Results

The Kujala score increased from a mean of 55 (range, 15-81) preoperatively to 82.5 (range, 53-98) after 12 months (95% CI, -42.56 to -12.37; P < .001) and to 84.2 (range, 59-99) after 24 months (95% CI, -44.29 to -14.11; P < .001). The intensity of PFP decreased from 5.7 (range, 3-10) preoperatively to 1.4 (range, 0-4) after 12 months (95% CI, 2.57 to 5.96; P < .001) and had a mean of 1.6 (range, 0-6) after 24 months (95% CI, 2.44 to 5.75; P < .001). Preoperatively, parameters in the study group indicated significant patellotrochlear malalignment, which improved and normalized (except for the LTI angle) postoperatively compared with the values of the control group (P > .05).

Conclusion

In a subgroup of patients with chronic PFP due to severe trochlear dysplasia, deepening trochleoplasty and concomitant realignment procedures significantly reduced pain and improved knee joint function while normalizing patellotrochlear congruence.

Quality assurance of radiotherapy in the ongoing EORTC 1420 "Best of" trial for early stage oropharyngeal, supraglottic and hypopharyngeal carcinoma: results of the benchmark case procedure

INTRODUCTION

The current phase III EORTC 1420 Best-of trial (NCT02984410) compares the swallowing function after transoral surgery versus intensity modulated radiotherapy (RT) in patients with early-stage carcinoma of the oropharynx, supraglottis and hypopharynx. We report the analysis of the Benchmark Case (BC) procedures before patient recruitment with special attention to dysphagia/aspiration related structures (DARS).

MATERIALS AND METHODS

Submitted RT volumes and plans from participating centers were analyzed and compared against the gold-standard expert delineations and dose distributions. Descriptive analysis of protocol deviations was conducted. Mean Sorensen-Dice similarity index (mDSI) and Hausdorff distance (mHD) were applied to evaluate the inter-observer variability (IOV).

RESULTS

65% (23/35) of the institutions needed more than one submission to achieve Quality assurance (RTQA) clearance. OAR volume delineations were the cause for rejection in 53% (40/76) of cases. IOV could be improved in 5 out of 12 OARs by more than 10 mm after resubmission (mHD). Despite this, final IOV for critical OARs in delineation remained significant among DARS by choosing an aleatory threshold of 0.7 (mDSI) and 15 mm (mHD).

CONCLUSIONS

This is to our knowledge the largest BC analysis among Head and neck RTQA programs performed in the framework of a prospective trial. Benchmarking identified non-common OARs and target delineations errors as the main source of deviations and IOV could be reduced in a significant number of cases after this process. Due to the substantial resources involved with benchmarking, future benchmark analyses should assess fully the impact on patients' clinical outcome.

Patient-Reported Outcomes After Revision Surgery for Failed Medial Patellofemoral Ligament Reconstruction: A Matched-Pair Analysis Including Correction of Predisposing Factors

BACKGROUND

Complications and the need for revision surgery after medial patellofemoral ligament reconstruction (MPFLR) are evident in the current literature. However, there is a shortage of clinical data evaluating the results of revision surgery in individual patients after failed MPFLR.

PURPOSE

To investigate the results of tailored revision surgery for failed MPFLR, including the correction of predisposing factors.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Between August 2015 and March 2019, 25 patients (male:female, n = 9:16; mean ± SD age, 25.9 ± 6.5 years) underwent revision surgery for failed MPFLR (study group). The Banff Patella Instability Instrument 2.0 (BPII 2.0) and a numerical analog scale (0-10) for patellofemoral pain and subjective knee joint function were used to assess patient-reported quality of life before and after revision surgery. The control group of 50 patients (male:female, n = 18:32; age, 22.8 ± 4.3 years) who underwent identical patellar-stabilizing procedures was matched 1:2 by the surgical procedure, predisposing factors, sex, age, and follow-up time.

RESULTS

Evaluation was performed postoperatively at a mean 27.8 ± 14.0 months (range, 12-54 months) in the study group and 26.1 ± 11.2 months (range, 12-56 months) in the control group (P = .55). The BPII 2.0 score increased from 28.6 ± 17.9 points to 68.7 ± 22.3 points (P < .0001) in the study group and from 43.8 ± 22.5 points to 75.5 ± 21.4 points (P < .0001) in the control group from preoperatively to postoperatively, respectively. Before revision surgery, the BPII 2.0 scores in the study group were significantly inferior to those in the control group (P = .0026). At the final follow-up, the BPII 2.0 score in the study group was not significantly lower (P = .174), and a similar number of patients in the study group and the control group achieved the minimally clinically important difference (P = .49). Patellofemoral pain and subjective knee joint function improved significantly in both groups (P < .0001, P < .0001), without any significant difference between them at the final follow-up (P = .85, P = .86).

CONCLUSION

Revision surgery for MPFLR failure, including the correction of major anatomic risk factors, yielded a significant improvement in patient-reported quality-of-life outcome measures. Patients with failed MPFLR, however, were significantly more restricted before revision surgery than patients without previous interventions when evaluated with the BPII 2.0.

Impact of the gut microbiome on the atorvastatin-dependent modulation of the serum lipidome

Background and aims

The modulation of serum lipids, in particular of the low-density lipoprotein cholesterol (LDL-C), by statins varies between individuals. The mechanisms regulating this interindividual variation are only poorly understood. Here, we investigated the relation between the gut microbiome and the regulatory properties of atorvastatin on the serum lipidome using mice with depleted gut microbiome.

Methods

Over a period of 6 weeks, mice (C57BL/6) with either an intact (conventional mice, CONV, n=24) or antibiotic-based depleted gut microbiome (antibiotic treated mice, ABS, n=16) were put on standard chow diet (SCD) or high fat diet (HFD), respectively. During the last 4 weeks of treatment atorvastatin (Ator, 10mg/kg body weight/day) or control vehicle was administered via daily oral gavage. Blood lipids (total cholesterol, VLDL, LDL-C, HDL-C) and serum sphingolipids were compared among the groups. The expressions of hepatic and intestinal genes involved in cholesterol metabolism were analyzed by qRT-PCR. Alterations in the gut microbiota profile of mice with intact gut microbiome were examined using 16S RNA qRT-PCR.

Results

In CONV mice, HFD led to significantly increased blood LDL-C levels as compared with SCD (HFD: 36.8±1.4 mg/dl vs. SCD: 22.0±1.8 mg/dl; P&lt;0.01). In CONV mice atorvastatin treatment significantly reduced blood LDL-C levels after HFD, whereas in ABS mice the LDL-C lowering effect of atorvastatin was markedly attenuated (CONV+HFD+Ator: 31.0±1.8 mg/dl vs. ABS+HFD+Ator: 46.4±3 mg/dl; P&lt;0.01). A significant reduction in the abundance of several plasma lipids, in particular sphingolipids and glycerophospholipids upon atorvastatin treatment was observed in CONV mice, but not in ABS mice. The expressions of distinct hepatic and intestinal cholesterol-regulating genes (ldlr, srebp2, pcsk9 and npc1l1) upon atorvastatin treatment were significantly altered in gut microbiota depleted mice. In response to HFD a decrease in the relative abundance of the bacterial phyla Bacteroides and an increase in the relative abundance of Firmicutes was observed. The altered ratio between Bacteroides and Firmicutes in HFD fed mice was partly reversed upon atorvastatin treatment.

Conclusions

Our findings indicate a crucial role of the gut microbiome for the regulatory properties of atorvastatin on the serum lipidome and, in turn, support a critical impact of atorvastatin on the gut microbial composition. The results provide novel insights into potential microbiota related mechanisms underlying interindividual variation in modulation of the serum lipidome by statins, given interindividual differences in microbiome composition and function.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): German Heart Research Foundation

54Role of the gut microbiome for the cholesterol lowering effect of atorvastatin

Background and aims

Statins show interindividual differences in the extent of low-density lipoprotein cholesterol (LDL-C) reduction. The mechanisms of this interindividual variation are not fully understood. Here, we examined the potential role of the gut microbiome for the LDL-C lowering property of atorvastatin.

Methods

Mice (C57BL/6) with either intact (conventional mice, CONV, n=24) or with antiobiotic depleted gut microbiome (gnotobiotic, n=16), were put on standard chow diet (SCD) (n=11) or high fat diet (HFD) (n=29) for 6 weeks. During the last 4 weeks atorvastatin (Ator, 10mg/kg body weight/day) or control vehicle was orally applied via gavage. Blood levels of LDL-C and glucose and body weight after 6 weeks of treatment were compared between the groups. Expression of genes involved in hepatic and intestinal cholesterol-metabolism were examined. Faeces of CONV mice were analyzed for alteration of the gut microbiota profile upon atorvastatin treatment using 16S rRNA qPCR.

Results

HFD fed mice with intact gut microbiome showed significantly increased blood LDL-C levels as compared to SCD (HFD: 36.8±1.4 mg/dl vs. SCD: 22.0±1.8 mg/dl; P<0.01). Bodyweight gain or blood glucose levels after HFD were not significantly different between CONV and gnotobiotic mice. While in CONV mice atorvastatin significantly reduced LDL-C levels after HFD, in gnotobiotic mice the LDL-C lowering effect of atorvastatin was attenuated (CONV+HFD+Ator: 31.0±1.8 mg/dl vs. gnotobiotic mice+HFD+Ator: 46.4±3 mg/dl; P<0.01). The expression of genes involved in hepatic cholesterol synthesis was not significantly altered in gnotobiotic mice as compared to CONV mice. In CONV mice HFD decreased the relative abundance of the bacterial phyla Bacteroidetes and increased the abundance of Firmicutes as compared to SCD. The ratio between Firmicutes to Bacteroidetes was shifted towards control conditions upon atorvastatin treatment.

Conclusions

The results of this study suggest a regulatory impact of atorvastatin on the gut-microbial profile and, in turn, a crucial role of the gut-microbiome for the LDL-C lowering effect of atorvastatin independent of its regulation of hepatic cholesterol synthesis. Our findings provide novel insight into potential microbiota-related mechanisms causing interindividual variation in LDL-C lowering effects of statins.

Acknowledgement/Funding

German Heart Research Foundation

Comparison of the antibacterial efficacy of sonic- and two ultrasonic-activated irrigation techniques in reducing intracanal Enterococcus faecalis populations

OBJECTIVE

This in-vitro study evaluated the antibacterial efficacy of sonic and ultrasonic irrigation with either intermittent or continuous flush in root canals infected with Enterococcus faecalis.

METHOD AND MATERIALS

Seventy single-rooted, extracted teeth with straight root canals were prepared with FlexMaster NiTi-instruments, sterilized, inoculated with E faecalis and incubated for 72 hours. Sixty roots were randomly divided into four experimental groups as well as into infection and sterile controls (n = 10 each). The remaining teeth were used for SEM analysis of smear layer removal (n = 5) and infection with E faecalis (n = 5). Irrigation in the experimental groups was performed with 1% NaOCl and syringe irrigation, sonic activation of the irrigant with EndoActivator, ultrasonic activation with intermittent flush, or ultrasonic activation with continuous flush. Microbial sampling was performed by collecting dentin shavings from the root canal walls. Colony-forming units were counted and statistical analysis was performed using nonparametric rank-based ANOVA-type tests for longitudinal data (P < .05).

RESULTS

A significant reduction of E faecalis of 3 log10 steps compared to the infection control was achieved by all irrigation techniques (P < .0001). There were no significant differences in antibacterial efficacy between syringe irrigation, sonically, or ultrasonically activated irrigation (P > .45).

CONCLUSION

Activation of 1% NaOCl with either sonic or ultrasonic devices did not increase the antimicrobial efficacy against E faecalis compared to conventional syringe irrigation in straight root canals.

Deepening trochleoplasty and medial patellofemoral ligament reconstruction normalize patellotrochlear congruence in severe trochlear dysplasia

AIMS

The aim of this study was to evaluate cartilaginous patellotrochlear congruence and patellofemoral alignment parameters after deepening trochleoplasty in severe trochlear dysplasia.

PATIENTS AND METHODS

The study group comprised 20 patients (two male, 18 female; mean age 24 years (16 to 39)) who underwent deepening trochleoplasty and medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent lateral patellar dislocation due to severe trochlear dysplasia (Dejour type B to D). Pre- and postoperative MRI investigations of the study group were compared with MRI data of 20 age- and gender-matched control patients (two male, 18 female; mean age 27 years (18 to 44)) regarding the patellotrochlear contact ratio, patellotrochlear contact area, posterior patellar edge-trochlear groove ratio, and patellar tilt.

RESULTS

Preoperatively, all parameters in the study group indicated significant patellar malalignment, including a reduced patellotrochlear contact ratio (mean 0.38 (0.13 to 0.59) vs mean 0.67 (0.48 to 0.88); p < 0.001), reduced contact area (mean 128 mm² (87 to 190) vs mean 183 mm² (155 to 227); p < 0.001), increased patellar lateralization (mean 0.82 (0.55 to 1.0) vs mean 0.99 (0.93 to 1.1); p < 0.001) and increased patellar tilt (mean 25.8° (8.1° to 43.0°) vs mean 9.1° (0.5° to 16.8°); p < 0.001). Postoperatively, all parameters in the study group improved significantly and reached normal values compared with the control group. The patellotrochlear contact ratio increased to a mean of 0.63 (0.38 to 0.85) (p < 0.001), the contact area increased to a mean of 187 mm² (101 to 255) (p < 0.001), the posterior patellar edge-trochlear groove ratio improved to a mean of 0.96 (0.83 to 0.91) (p < 0.001), and the patellar tilt decreased to a mean of 13.9° (8.1° to 22.1°) (p < 0.001) postoperatively.

CONCLUSION

Deepening trochleoplasty and MPFL reconstruction normalized the patellotrochlear congruence and patellofemoral alignment parameters. Modifying the dysplastic trochlea involves approximating the trochlear morphology to the shape of the patella rather than inducing a patella and trochlea mismatch. Cite this article: Bone Joint J 2019;101-B:325-330.

[Performance control after arthroscopic arthrolysis with capsulectomy in fresh-frozen elbow joints]

BACKGROUND AND OBJECTIVE

Posttraumatic or postoperative movement restrictions in elbow joints can often occur (including capsular contracture) and can generate everyday limitations. In persistent elbow stiffness, arthroscopic arthrolysis with removal of the dorsal and ventral capsule portions can be carried out. The purpose of this study was to assess the efficacy of arthroscopic capsulectomy by means of an in vitro anatomical study.

METHODS

A standardized elbow arthroscopy with ventral and dorsal capsulectomy was performed and image-documented in five fresh-frozen elbow specimens. Subsequently, open dissection of the elbow joint was performed to analyze the amount of residual capsule by means of photodocumentation of the specimens.

RESULTS

Regardless of the surgeon and surgical experience, anterior and posterior remnants of the capsule remained in all specimens. Dorsal capsule strands around the standard arthroscopy portals were noticed particularly more often in the area of the high dorsolateral camera portal. An incomplete capsulectomy was seen on the ulnar side at the level of the posterior medial ligament (PML) in the immediate vicinity of the ulnar nerve. Ventrally, a capsulectomy was performed from the radial side and also the ulnar side until the brachialis muscle and additionally a complete capsulectomy as far as the anterior medial ligament (AML) and radial collateral ligament (RCL) was achieved. The capsule was completely resected in a proximal direction. Distally, irrelevant capsular remnants were found in the region of the annular ligament and distal of the tip of the coronoid process.

CONCLUSION

Arthroscopic arthrolysis can be performed with a high degree of radicality. The radicality must be self-critically taken into account in one's own action. The radicality of the portal change may even be higher ventrally than with an isolated column procedure. On the other hand, it must be critically considered that posteriorly, the PML cannot be adequately addressed by means of arthroscopy due to the risk of ulnar nerve injury. Portal changes might help to enable a more complete visualization of the joint capsule and may avoid leaving possibly relevant remnants of the capsule. If a release of the PML is required, this may have to be carried out in combination with an ulnar nerve release in a mini-open technique.

Coherent Beam-Beam Instability in Collisions with a Large Crossing Angle

In recent years the "crab-waist collision" scheme [P. Raimondi, Proceedings of 2nd SuperB Workshop, Frascati, 2006.; M. Zobov et al., Phys. Rev. Lett. 104, 174801 (2010)PRLTAO0031-900710.1103/PhysRevLett.104.174801] has become popular for circular e^{+} e^{-} colliders. The designs of several future colliders are based on this scheme. So far the beam-beam effects for collisions under a large crossing angle with or without crab waist were mostly studied using weak-strong simulations. We present here strong-strong simulations showing a novel strong coherent head-tail instability, which can limit the performance of proposed future colliders. We explain the underlying instability mechanism starting from the "cross-wake force" induced by the beam-beam interaction. Using this beam-beam wake, the beam-beam head tail modes are studied by an eigenmode analysis. The instability may affect all collider designs based on the crab-waist scheme. We suggest an experimental verification at SuperKEKB during its commissioning phase II.

Biocompatibility and degradation of LAE442-based magnesium alloys after implantation of up to 3.5years in a rabbit model

Magnesium as basic implant material has long been the center of orthopedic research. Latest progress is achieved with a European certification and clinical use of a magnesium based compression screw. However, long term studies with implantation duration that exceed one year considerably do not exist. The present examinations analyzed the degradation progress from nine months to 3.5year after implantation of cylindrical pins into the medullary cavity of New Zealand White rabbits. Evaluation included clinical assessment, in vivo μ-computed tomography, analysis of the implants by three-point-bending and examination of the adjacent tissue by means of histology and of inner organs by mass- and optical emission spectrometry using inductively coupled plasma. Clinical acceptance was without objections in all animals. Immoderate reaction of the surrounding bone could be found in neither of the applied techniques. While in vivo μ-computed tomography showed a very slow degradation rate up to 72weeks, three-point-bending revealed a percentage loss of F(max) of 41.1% for implants after 9months implantation and 88.47% for the implant after 3.5years implantation. Although the total amounts of RE detected in the inner organs were very low, the organs of rabbits with LAE442 cylinders showed 10-20-fold increased concentrations of the alloying elements lanthanum, cerium, neodymium and praseodymium compared to animals without any implanted material.

STATEMENT OF SIGNIFICANCE

This is the first animal study investigating the degradation process of a magnesium alloy in vivo for up to 3.5years. Currently available data from different other in vivo studies cover only implantation durations up to one year. Therefore, the analysis of these long-time effects in the present study is highly significant and of great interest. Comprehensive outcome achieved by different techniques was assessed. The degradation process was slow and homogenous. Maximum applied force (F(max)) reduced by 41.1% for implants after 9months and by 88.47% for the implant after 3.5years implantation. Total amounts of RE detected in the inner organs were very low; the organs of rabbits with LAE442 cylinders showed 10-20-fold increased concentrations.

Registration procedure for spatial correlation of physical energy deposition of particle irradiation and cellular response utilizing cell-fluorescent ion track hybrid detectors

The hybrid technology cell-fluorescent ion track hybrid detector (Cell-Fit-HD) enables the investigation of radiation-related cellular events along single ion tracks on the subcellular scale in clinical ion beams. The Cell-Fit-HD comprises a fluorescent nuclear track detector (FNTD, the physical compartment), a device for individual particle detection and a substrate for viable cell-coating, i.e. the biological compartment. To date both compartments have been imaged sequentially in situ by confocal laser scanning microscopy (CLSM). This is yet in conflict with a functional read-out of the Cell-Fit-HD utilizing a fast live-cell imaging of the biological compartment with low phototoxicity on greater time scales. The read-out of the biological from the physical compartment was uncoupled. A read-out procedure was developed to image the cell layer by conventional widefield microscopy whereas the FNTD was imaged by CLSM. Point mapping registration of the confocal and widefield imaging data was performed. Non-fluorescent crystal defects (spinels) visible in both read-outs were used as control point pairs. The accuracy achieved was on the sub-µm scale. The read-out procedure by widefield microscopy does not impair the unique ability of spatial correlation by the Cell-Fit-HD. The uncoupling will enlarge the application potential of the hybrid technology significantly. The registration allows for an ultimate correlation of microscopic physical beam parameters and cell kinetics on greater time scales. The method reported herein will be instrumental for the introduction of a novel generation of compact detectors facilitating biodosimetric research towards high-throughput analysis.

Femtosecond laser written nanostructures in Ge-doped glasses

We report on nanostructures induced by femtosecond laser pulses in the bulk of Germanium-doped silica glasses. For studying structural properties of the nanostructure constituents small-angle x-ray scattering and SEM served to map pore size, filling factor and periodicity. Our results show that with increasing the Ge doping concentration, the aspect ratio (transverse to inscribing laser) of nanometric pores rises while they arrange in a smaller period in contrast to nanogratings in pristine fused silica. Consequently, higher optical retardance can be obtained demonstrating the pronounced glass decomposition due to the changing network structure.

On the rewriting of ultrashort pulse-induced nanogratings

In this study, we report on the erasure and rewriting of nanogratings by femtosecond laser pulses in the bulk of fused silica. To map the structural processes during rewriting, a combination of optical retardance measurement, small angle X-ray scattering, and scanning electron microscopy was used. The results reveal that already few pulses lead to erasure and formation of anisotropic structures. Repetitive rewriting favors the formation of nanoscopic pores, which increases the optical retardance of nanogratings for large pulse numbers.

Aggressive Breast Cancer during Pregnancy with a Rare Form of Metastasis in the Maternal Placenta

Breast cancer is the second most common cancer diagnosed during pregnancy. Here we describe a 29-year-old patient with a recurrence of breast cancer with simultaneous brain, pulmonary and placenta metastasis. An overview of the literature on placenta metastases is provided together with a report on the interdisciplinary medical management.

Experimental validation of a novel compact focusing scheme for future energy-frontier linear lepton colliders

A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.

Prediction of residential radon exposure of the whole Swiss population: comparison of model-based predictions with measurement-based predictions

Radon plays an important role for human exposure to natural sources of ionizing radiation. The aim of this article is to compare two approaches to estimate mean radon exposure in the Swiss population: model-based predictions at individual level and measurement-based predictions based on measurements aggregated at municipality level. A nationwide model was used to predict radon levels in each household and for each individual based on the corresponding tectonic unit, building age, building type, soil texture, degree of urbanization, and floor. Measurement-based predictions were carried out within a health impact assessment on residential radon and lung cancer. Mean measured radon levels were corrected for the average floor distribution and weighted with population size of each municipality. Model-based predictions yielded a mean radon exposure of the Swiss population of 84.1 Bq/m(3) . Measurement-based predictions yielded an average exposure of 78 Bq/m(3) . This study demonstrates that the model- and the measurement-based predictions provided similar results. The advantage of the measurement-based approach is its simplicity, which is sufficient for assessing exposure distribution in a population. The model-based approach allows predicting radon levels at specific sites, which is needed in an epidemiological study, and the results do not depend on how the measurement sites have been selected.

Formation of periodic disruptions induced by heat accumulation of femtosecond laser pulses

The absorption and heat accumulation of successive ultrashort laser pulses in fused silica leads to melting of the material. We analyze the structure and formation of disruptions that occur within the trace of the molten material. We employed focused ion beam (FIB) milling to reveal the inner structure of these disruptions. The disruptions consist of several small voids which form a large cavity with a diameter of several tens of micrometer. Based on the observations, we suggest a model explaining the formation of these disruptions as a results of a fast quenching process of the molten material after the laser irradiation has stopped. In addition, we analyzed the periodic and non-periodic formation of disruptions. The processing parameters strongly influence the formation of disruptions.

Clinical, molecular- and cytogenetic analysis of a case of severe radio-sensitivity

In radiotherapy the normal tissue reaction is often a limiting factor for radiation treatment. Still there is no screening method, which predicts normal tissue reaction on radiotherapy, especially in comparison to tumor tissue, and therefore allows tailoring of the radiation dose to each patient. Here, we present a case of severe radiation-related side effects. We applied classical cytogenetic techniques (Giemsa-banding and staining of centromeric regions), the comet assay as well as multicolor fluorescence in situ hybridization on peripheral blood lymphocytes of this patient in order to determine the radio-sensitivity on the DNA level and to correlate these findings with the clinical outcome. Our investigations revealed abnormalities on chromosome 9, deficiencies in the DNA-repair capacity after radiation exposure and a high number of radiation induced chromosomal aberrations. A detected high amount of residual damage two or three hours after radiation exposure and repair as well as the high number of chromosomal aberrations (ChAs) suggests a correlation between repair capacity and radiation induced ChAs. We concluded that the detected abnormalities might serve as a genetic basis for the radio-sensitive phenotype of this patient. Taken together this report strengthens the idea that intensive DNA genomic analysis of individual patients can serve as the basis for more favourable treatment of cancer patients.

Ultrastable bonding of glass with femtosecond laser bursts

We report on the welding of fused silica with bursts of ultrashort laser pulses. By optimizing the burst frequency and repetition rate, we were able to achieve a breaking resistance of up to 96% of the bulk material, which is significantly higher than conventional high repetition rate laser bonding. The main reason for this stability increase is the reduced stress in the surroundings of the laser induced weld seams, which is proven by measurements of the stress-induced birefringence. A detailed analysis of the shape of the molten structures shows elongated structures in the burst regime. This can be attributed to stronger heating, which is supported by our thermodynamic simulations of the laser melting and bonding process.

New approach to resonance crossing

Time-varying nonlinear oscillatory systems produce phenomena of resonance crossing and trapping of particles in resonance islands. Traditionally, such processes have been analyzed in terms of adiabatic conditions. Considering, as an example, a simplified one-dimensional model describing the "electron-cloud pinch" during a bunch passage in a particle accelerator, here we present an approach to resonance trapping which does not require any adiabatic condition. Instead we introduce the concept of the attraction point and investigate invariance and scaling properties of motion close to the attraction point, considering a single resonance crossing.

First estimation of Eurasian lynx (Lynx lynx) abundance and density using digital cameras and capture–recapture techniques in a German national park

Eurasian lynx are individually identifiable by their unique coat markings, making them ideal candidates for capture–recapture (CMR) surveys. We evaluated the use of digital photography to estimate Eurasian lynx population abundance and density within the Bavarian Forest National Park. From November 2008 to January 2009 we placed 24 camera trap sites, each with two cameras facing each other on well–used walking tracks). The units were placed based on a systematic grid of 2.7 km. We captured five independent and three juvenile lynx and calculated abundance estimates using Program Mark. We also compared density estimates based on the MMDM method (Mean Maximum Distance Moved) from telemetry data (½MMDMGPS) and from camera trapping data (½MMDMCAM). We estimated that in an effectively sampled area of 664 km2 the Eurasian lynx density was 0.9 individuals/100 km2 with ½MMDMCAM. The Eurasian lynx density calculated with ½MMDMGPS was 0.4 individuals/100 km2 in an effectively sampled area of 1,381 km2. Our results suggest that long–term photographic CMR sampling on a large scale may be a useful tool to monitor population trends of Eurasian lynx in accordance with the Fauna–Flora–Habitat Directive of the European Union.

[Modern radiotherapeutic concept - stereotactic, adjuvant, palliative]

Radiotherapy is an important and well integrated part in modern treatment concepts for cancer of the lung and pleura. Thanks to technical progress in the last years radiotherapy has managed to prove its role in all stages of lung cancers and has opened a spectrum of new treatment options. Stereotactic radiotherapy of the early NSCLC has become the standard treatment for radically inoperable patients. It provides better local control rates than traditional conventionally fractionated radiotherapy. In stage III NSCLC, simultaneous radiochemotherapy is an effective option with equal results compared to surgery. The standard treatment for limited disease SCLC is primary simultaneous radiochemotherapy. All patients with good response after primary treatment profit from prophylactic cranial irradiation. Adjuvant radiotherapy is a component of the trimodal treatment for curative approaches in patients with pleura mesothelioma. Palliative radiotherapy is the standard treatment for brain metastases, bone metastases and compression or obstruction from thoracal tumour mass.