Does the cement stiffness affect fatigue fracture strength of vertebrae after cement augmentation in osteoporotic patients?

Purpose

Normal progression of osteoporosis or the rigid reinforcement of the fractured vertebral body with polymethyl methacrylate (PMMA) cement is being discussed as a cause for adjacent-level fractures after vertebroplasty. The purpose of this study was to investigate whether augmentation with low stiffness cement can decrease the risk of adjacent-level fractures in low-quality bone.

Methods

Eighteen female osteoporotic lumbar specimens (L1–L5) were harvested and divided into three groups according to bone mineral density: (I) native; (II) PMMA; (III) modified PMMA (lower stiffness). For the PMMA and modified PMMA groups, a compression fracture was first mechanically induced in L3, and then the fracture received vertebroplasty treatment. The cement stiffness reduction of the modified PMMA group was achieved via an addition of 8 mL of serum to the typical PMMA base. All specimens were exposed to cyclic loading (4 Hz) and a stepwise increasing applied peak force. Cement stiffness was tested according to ISO 5833.

Results

A 51 % decrease in cement stiffness was achieved in the modified PMMA group (954 ± 141 vs. 1,937 ± 478 MPa, p < 0.001). Fatigue fracture force (the force level during cyclic loading at which the deformation experienced a sudden increase; FFF) was significantly affected by bone quality (r ² = 0.39, p = 0.006) and by the initial fracture force (the force necessary to create the initial fracture in L3 prior to augmentation; r ² = 0.82, p < 0.001). Using initial fracture force as a covariate, the FFF of the modified PMMA group (1,764 ± 49 N) was significantly higher than in the PMMA group (1,544 ± 55 N; p = 0.03).

Conclusions

A possible method to reduce adjacent-level fractures after vertebroplasty in patients with reduced bone quality could be the use of a lower modulus cement. Therefore, mixing cement with biocompatible fluids could prove useful to tailor cement properties in the operating theater.     

Comparison of total body irradiation versus non-total body irradiation containing regimens for de novo acute myeloid leukemia in children

With limited data comparing hematopoietic cell transplant outcomes between myeloablative total body irradiation (TBI) containing and non-TBI regimens in children with de novo acute myeloid leukemia, the aim of this study was to compare transplant-outcomes between these regimens. Cox regression models were used to compare transplant-outcomes after TBI and non-TBI regimens in 624 children transplanted between 2008 and 2016. Thirty two percent (n=199) received TBI regimens whereas 68% (n=425) received non-TBI regimens. Five-year non-relapse mortality was higher with TBI regimens (22% vs. 11%, P<0.0001) but relapse was lower (23% vs. 37%, P<0.0001) compared to non-TBI regimens. Consequently, overall (62% vs. 60%, P=1.00) and leukemia-free survival (55% vs. 52%, P=0.42) did not differ between treatment groups. Grade 2-3 acute graft versus host disease was higher with TBI regimens (56% vs. 27%, P<0.0001) but not chronic graft versus host disease. The 3-year incidence of gonadal or growth hormone deficiency was higher with TBI regimens (24% vs. 8%, P<0.001) but there were no differences in late pulmonary, cardiac or renal impairment. In the absence of a survival advantage, the choice of TBI or non-TBI regimen merits careful consideration with the data favoring non-TBI regimens to limit the burden of morbidity associated with endocrine dysfunction.     

Navigation system for minimally invasive esophagectomy: experimental study in a porcine model

Background

Navigation systems potentially facilitate minimally invasive esophagectomy and improve patient outcome by improving intraoperative orientation, position estimation of instruments, and identification of lymph nodes and resection margins. The authors’ self-developed navigation system is highly accurate in static environments. This study aimed to test the overall accuracy of the navigation system in a realistic operating room scenario and to identify the different sources of error altering accuracy.

Methods

To simulate a realistic environment, a porcine model (n = 5) was used with endoscopic clips in the esophagus as navigation targets. Computed tomography imaging was followed by image segmentation and target definition with the medical imaging interaction toolkit software. Optical tracking was used for registration and localization of animals and navigation instruments. Intraoperatively, the instrument was displayed relative to segmented organs in real time. The target registration error (TRE) of the navigation system was defined as the distance between the target and the navigation instrument tip. The TRE was measured on skin targets with the animal in the 0° supine and 25° anti-Trendelenburg position and on the esophagus during laparoscopic transhiatal preparation.

Results

On skin targets, the TRE was significantly higher in the 25° position, at 14.6 ± 2.7 mm, compared with the 0° position, at 3.2 ± 1.3 mm. The TRE on the esophagus was 11.2 ± 2.4 mm. The main source of error was soft tissue deformation caused by intraoperative positioning, pneumoperitoneum, surgical manipulation, and tissue dissection.

Conclusion

The navigation system obtained acceptable accuracy with a minimally invasive transhiatal approach to the esophagus in a realistic experimental model. Thus the system has the potential to improve intraoperative orientation, identification of lymph nodes and adequate resection margins, and visualization of risk structures. Compensation methods for soft tissue deformation may lead to an even more accurate navigation system in the future.     

Calcium homeostasis influences radiological fracture healing in postmenopausal women

Introduction

Recent studies suggest that calcium and 25-[OH]-cholecalciferol represent substantial co-factors in fracture healing. However, there still seems to be no sustainable consensus regarding the influence on fracture healing patterns. In this study, the influence of calcium and vitamin D levels on fracture callus formation was prospectively analysed using pQCT scan.

Methods

94 postmenopausal females with distal radius fractures and consecutive surgery were included. Calcium, 25-[OH]-cholecalciferol, parathyroid hormone and bone-specific alkaline phosphatase levels were obtained prior surgical treatment and after 6 weeks. A pQCT scan was performed on both sites. Bone mineral density and fracture callus area were determined after detecting the outer border contour at a threshold of 280 mg/ccm. Patients received daily supplements of 1000 mg calcium and 880 IU 25-[OH]-cholecalciferol.

Results

Mean 25-[OH]-cholecalciferol level was 19.61 ± 21.87 ng/ml, mean parathyroid hormone level was 52.6 ± 58.9 ng/l and mean Ca level was 2.23 ± 0.35 mmol/l. After 6 weeks of supplementation a significant increase of calcium (p < 0.001) and 25-[OH]-cholecalciferol (p < 0.001), and a significant decrease of parathyroid hormone (p < 0.001) levels were observed. Sixth week follow-up fracture callus area correlated significantly with postoperative normal range calcium levels on the fractured site (p = 0.006). Bone mineral density correlated with age (p < 0.001), but not with calcium and 25-[OH]-cholecalciferol levels after 6 weeks. All fractures presented timely adequate callus formation.

Conclusion

Calcium and parathyroid hormone serum levels influence fracture callus area interpreted as fracture callus formation patterns. Calcium levels within physiological range accounted for highest fracture callus area. Therefore, a balanced calcium homeostasis is required for appropriate callus formation.     

Does prenatal nicotine exposure alter the brain's response to nicotine in adolescence? A neuroanatomical analysis

This study examined changes in dendritic morphology and spine density in multiple brain regions [Zilles' areas: (i) the Cg3 region of the anterior cingulate cortex or the medial prefrontal cortex, layer III (Cg3); (ii) the dorsal agranular insular cortex, layer III (AID); (iii) the PAR I region of the parietal cortex, layer III (Par1) and (iv) the nucleus accumbens (NAc)]of Long–Evans rats following exposure to nicotine prenatally, in late adolescence, or both prenatally and in adolescence. Prenatal nicotine exposure induced enduring changes in neuroanatomical organisation that varied between male and female offspring, with males exhibiting increased dendritic complexity of neurons in AID and NAc whereas females experienced increased dendritic complexity in Par1 but decreased dendritic complexity of neurons in NAc. Similarly, nicotine given in late adolescence dramatically reorganised neural circuitry of both male and female offspring, with males exhibiting decreased dendritic complexity of neurons in Par1 and Cg3 but increased dendritic complexity in AID, and females exhibiting decreased dendritic complexity in Cg3 and NAc but increased complexity in AID. Exposure to nicotine both prenatally and in adolescence produced few neuroanatomical parameters that demonstrated a prenatal experience × adolescent drug administration interaction. Females showed additive effects in Par1, Cg3 and NAc whereas males demonstrated additive effects only in AID. Thus, the timing of nicotine exposure produced differential effects on cerebral organisation in a regionally specific manner.     

Chronic inhibition of cyclooxygenase-2 induces dendritic hypertrophy and limited functional improvement following motor cortex stroke

The cyclooxygenase-2 (COX-2) enzyme is part of the inflammatory pathway and is induced within the brain by a variety of pathological events, including ischemia. Pharmacological agents that inhibit COX-2 have been found to be neuroprotective in a number of injury models, and long-term administration of these drugs has been shown to induce plastic changes in the brain. In the current experiment, we investigated the effectiveness of stimulating cortical plasticity following stroke injury through the administration of the COX-2 inhibitor drug NS398. Furthermore, we determined whether the induced plastic changes improved functional outcome following motor cortex stroke. Chronic drug administration was found to induce dendritic hypertrophy in cells in the parietal cortex, and this anatomical change was associated with the animals making significantly more reach attempts, as well as successful reaches during a skilled reaching task. Additional motor tests however revealed that the treatment did not affect the level of motor recovery, as the animals showed chronic impairments in the Schallert cylinder, and the forepaw inhibition tasks. Short-term administration of the drug, immediately following the stroke did not induce any dendritic changes, nor was it found to improve behavioral performance on any of the motor tasks. Based on these results we conclude that the plastic changes that are induced by long-term COX-2 inhibitor administration provide some benefit to functional outcome following ischemic cortical injury.     

Facial deformation following treatment for pediatric head and neck rhabdomyosarcoma; the difference between treatment modalities. Results of a trans-Atlantic,multicenter cross-sectional cohort study

Background

The four different local therapy strategies used for head and neck rhabdomyosarcoma (HNRMS) include proton therapy (PT), photon therapy (RT), surgery with radiotherapy (Paris-method), and surgery with brachytherapy (AMORE). Local control and survival is comparable; however, the impact of these different treatments on facial deformation is still poorly understood. This study aims to quantify facial deformation and investigates the differences in facial deformation between treatment modalities.

Methods

Across four European and North American institutions, HNRMS survivors treated between 1990 and 2017, more than 2 years post treatment, had a 3D photograph taken. Using dense surface modeling, we computed facial signatures for each survivor to show facial deformation relative to 35 age–sex–ethnicity-matched controls. Additionally, we computed individual facial asymmetry.

Findings

A total of 173 HNRMS survivors were included, survivors showed significantly reduced facial growth (p < .001) compared to healthy controls. Partitioned by tumor site, there was reduced facial growth in survivors with nonparameningeal primaries (p = .002), and parameningeal primaries (p ≤.001), but not for orbital primaries (p = .080) All patients were significantly more asymmetric than healthy controls, independent of treatment modality (p ≤ .001). There was significantly more facial deformation in orbital patients when comparing RT to AMORE (p = .046). In survivors with a parameningeal tumor, there was significantly less facial deformation in PT when compared to RT (p = .009) and Paris-method (p = .007).

Interpretation

When selecting optimal treatment, musculoskeletal facial outcomes are an expected difference between treatment options. These anticipated differences are currently based on clinicians’ bias, expertise, and experience. These data supplement clinician judgment with an objective analysis highlighting the impact of patient age and tumor site between existing treatment options.     

Der Weg zum Kompetenzzentrum für Adipositas und metabolische Chirurgie – Erfahrungen aus 2 verschiedenen Kliniken

Die Chirurgie - Bei hoher Prävalenz, stetig steigender Inzidenz der Adipositas und nachgewiesener Wirksamkeit adipositaschirurgischer Operationen (Ops) nehmen die Anzahl dieser OPs und die...     

Surgical therapy of breast cancer: to operate radically or to preserve the breast?

Surgical treatment, i.e. partial resection (R) versus modified radical mastectomy (M) in lymph node negative T1/2 patients and M versus the classical Halsted procedure (RM) in lymph node positive cases, as well as adjuvant treatment forms, namely chemotherapy (B) and chemoimmunotherapy (C) versus a control group treated by surgery only (A) have been evaluated in 241 patients with breast cancer follow up over a median observation time of 48 months. Whereas M showed significantly better results than R, no difference was detected between M and RM. The incidence of recurrence in the R group did not appear to be markedly reduced by cytotoxic treatment. In the same way, the data from a retrospective study on non-randomized patients treated by breast resection, showed a relatively high local recurrence rate (23.6%) at a median observation level of 10 years. Considering the various forms of surgical treatment for operable breast cancer by analysing the data from retrospective studies and prospective randomized trials from the literature as well as our own results, the only recommendation for the standard treatment of patients with primary operable breast cancer should be nothing less than modified radical mastectomy. Breast-conserving treatment forms should be tested only within the framework of controlled clinical trials.