Fixation strength of swelling copolymeric anchors in artificial bone

Fixation with suture anchors and metallic hardware for osteosynthesis is common in orthopedic surgeries. Most metallic commercial bone anchors achieve their fixation to bone through shear of the bone located between the threads. They have several deficiencies, including stress-shielding due to mechanical properties mismatch, generation of acidic by-products, poor osteointegration, low mechanical strength and catastrophic failure often associated with large bone defects that may be difficult to repair. To overcome these deficiencies, a swelling porous copolymeric material, to be used as bone anchors with osteointegration potential, was introduced. The purpose of this study was to investigate the fixation strength of these porous, swelling copolymeric bone anchors in artificial bone of various densities. The pull-out and subsidence studies indicate an effective fixation mechanism based on friction including re-fixation capabilities, and minimization of damage following complete failure. The study suggests that this swelling porous structure may provide an effective alternative to conventional bone anchors, particularly in low-density bone.

Overcoming the inhibitory effects of urea to improve the kinetics of microbial-induced calcium carbonate precipitation (MICCP) by Lysinibacillus sphaericus strain MB284

Among different microbial-induced calcium carbonate precipitation (MICCP) mechanisms utilized for biomineralization, ureolysis leads to the greatest yields of calcium carbonate. Unfortunately, it is reported that urea-induced growth inhibition can delay urea hydrolysis but it is not clear how this affects MICCP kinetics. This study investigated the impact of urea addition on the MICCP performance of Lysinibacillus sphaericus MB284 not previously grown on urea (thereafter named bio-agents), compared with those previously cultured in urea-rich media (20 g/L) (hereafter named bio-agents+ or bio-agents-plus). While it was discovered that initial urea concentrations exceeding 3 g/L temporarily hindered cell growth and MICCP reactions for bio-agents, employing bio-agents+ accelerated the initiation of bacterial growth by 33% and led to a 1.46-fold increase in the initial yield of calcium carbonate in media containing 20 g/L of urea. The improved tolerance of bio-agents+ to urea is attributed to the presence of pre-produced endogenous urease, which serves to reduce the initial urea concentration, alleviate growth inhibition, and expedite biomineralization. Notably, elevating the initial concentration of bio-agents+ from OD600 of 0.01 to 1, housing a higher content of endogenous urease, accelerated the initiation of MICCP reactions and boosted the ultimate yield of biomineralization by 2.6 times while the media was supplemented with 20 g/L of urea. These results elucidate the advantages of employing bio-agents+ with higher initial cell concentrations to successfully mitigate the temporary inhibitory effects of urea on biomineralization kinetics, offering a promising strategy for accelerating the production of calcium carbonate for applications like bio self-healing of concrete.

Numerical analysis of the mechanical response of novel swelling bone implants in polyurethane foams

In this study, a numerical framework was developed in order to analyze the swelling properties, mechanical response and fixation strength of swelling bone anchors. Using this framework, fully porous and solid implants, along with a novel hybrid design (consisting of a solid core and a porous sleeve), were modeled and studied. Free swelling experiments were conducted to investigate their swelling characteristics. The finite element model of swelling was validated using the conducted free swelling. Compared with the experimental data, results obtained from the finite element analysis proved the reliability of this frame-work. Afterwards, the swelling bone anchors were studied embedded in artificial bones with different densities with two different interface properties: considering frictional interface between the bone anchors and artificial bones (simulating the stages prior to osteointegration, when the bone and implant are not fully bonded and the surface of the implant can slide along the interface), and perfectly bonded (simulating the stages subsequent to osteointegration, when the bone and implant are fully bonded). It was observed that the swelling considerably decreases while the average radial stress on the lateral surface of the swelling bone anchor surges in the denser artificial bones. Ultimately, the pull-out experiments and simulations of the swelling bone anchors from the artificial bones were conducted to look into the fixation strength of the swelling bone anchors. It was found that the hybrid swelling bone anchor exhibits mechanical and swelling properties close to those of solid bone anchors, while also bone in-growth is expected to happen, which is an integral factor to these bone anchors.

454 Sinus of Valsalva Rupture

Background

Sinus of Valsalva (SVA) rupture is a rare cardiac pathology which is important to recognise and diagnose early.

Case Summary

This case report details a 30-year-old gentleman who presented with a 3-day history of dyspnoea and palpitations on a background of previous congenital heart disease. The patient's examination highlighted a continuous harsh pan-systolic murmur as well as an ECG finding of sinus tachycardia. Transthoracic echocardiography identified a ruptured Sinus of Valsalva. The patient was transferred to a cardiothoracic surgery centre and definitively treated with an aortic root and ventricular septal defect repair.

Discussion

This case highlights the clinical findings of a patient with an acute left to right shunt and the importance of early diagnosis and urgent surgery. This case emphasises the factors required to decide which surgical approach is appropriate such as the presence of aortic valvular pathology size, size of Sinus of Valsalva aneurysm, any simultaneous cardiac anomaly and the cardiac chamber involved.

Learning Points

Ovarian hyperstimulation syndrome on the acute medical unit: a problem-based review

Ovarian Hyperstimulation Syndrome (OHSS) is a spectrum of clinical features typically resulting from assisted conception techniques. With 2.35% of all live births in the UK resulting from in-vitro fertilisation (IVF), OHSS is on the rise. Moreover, there has been an increase in the presentation of its complications to GP surgeries and unscheduled acute care services nationwide. This review will discuss signs and symptoms of the increasingly common and potentially fatal complications of OHSS, namely pleural effusion, ascites and thromboembolic events. With such propensity toward critical, life-threatening events it is not only prudent to recognise the population at risk, but also to be aware of the signs, symptoms and complications to expedite treatment and ensure optimum outcome.

Outcomes of percutaneous pinning in treatment of distal radius fractures

Distal radius fractures are among the most common bone fractures all over the world. Close reduction and fixation by percutaneous pinning is a less invasive method comparing with other open surgeries. This study aims at evaluating the functional outcome of this treatment in distal radius fractures. In this prospective study, 50 patients with distal radius fractures underwent percutaneous pinning during a 16 month period in Tabriz Shohada Hospital. Follow-up for 3 months was possible in 48 (96%) patients. Possible complications (such as infection, nonunion, pin loosening and pain), functional outcomes (including range of motion, grip and pinch strengths) and radiological outcome were documented in intervals during follow-up. Forty eight patient, 22 males and 27 females with a mean age of 47.1 +/- 13.7 (19-80) years were enrolled. Local pain, infection and pin loosening were documented in 14.6, 16.7 and 2.1% of cases, respectively. Based on radiological reports, unacceptable palmar tilt, articular step, radial inclination and radial shortening were present in 6.3, 0, 2.1 and 6.3% of cases, respectively three months post-operation. The clinical outcomes according to Cooney's modification of the Green and O'Brien scheme were as excellent, good, fair and poor in 52.1, 31.3, 10.4 and 6.3% of cases, respectively. According to these results, closed reduction and percutaneous pinning of distal radius fractures is a rather successful method with minor complications.

High-sensitivity C-reactive protein (hs-CRP) and tumor necrotizing factor-alpha (TNF-alpha) after on- and off- pump coronary artery bypass grafting

INTRODUCTION

Coronary artery bypass grafting (CABG) is one of the most frequently performed operations around the world. The aim of this study is to evaluate high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-alpha (TNF-alpha) differences between on-pump and off-pump coronary surgery.

METHODS

In this prospective study, 90 patients with coronary artery disease referred for CABG were enrolled from July 2006-November 2007. Levels of hs-CRP and TNF-alpha were measured by ELISA using commercial kits

RESULTS

hs-CRP levels significantly (p<0.001) increase after CABG. But no difference between off-pump and on-pump groups was noted for hs-CRP and TNF-alpha levels (p=0.4, p=0.8).

CONCLUSIONS

There was no difference in high-sensitivity C-reactive protein (hs-CRP) and TNF-alpha between on-pump and off-pump CABG surgery.

Primary lumbar hernia repair: the open approach

BACKGROUND

Lumbar hernias arise through posterolateral abdominal wall defects, named inferior triangle (Petit) and superior triangle (Grynfelt). Most of the lumbar hernias are secondary to trauma or previous surgery, while primary lumbar hernias are rare. There are two possible surgical approaches: the anterior approach with lumbar incision and the laparoscopic (transabdominal or totally extraperitoneal) approach.

METHODS

We present a series of nine surgical procedures for primary lumbar hernia in 7 adult patients (2 affected by bilateral hernias). Seven were Grynfelt hernias, and two were Petit hernias. All surgical repairs were performed using synthetic mesh placed in the extraperitoneal space, below the muscular layers, using a tension-free technique.

RESULTS

There was no surgical complication, except for 1 case with a subcutaneous haematoma. The mean hospital stay was 2.3 days. All patients returned to normal daily activities within 15 days after surgery. After a median follow-up period of 25 months, there was no case of recurrence or postsurgical sequelae, such as pain or muscular weakness.

CONCLUSIONS

Primary lumbar hernias are rare congenital defects of the abdominal wall. Repair of these rare hernias can be successfully performed via the anterior approach with the use of synthetic mesh - this method of repair is easy, safe, and effective.

[Much ado about nothing]

The professional routine often allows us to forget over time not only the name, but often also the pathology for which a patient has recovered from and treated for with much "love and dedication". However some cases contribute to the baggage of a good doctor's experience and become nearly "proverbial" in nature. A 50 year old woman, affected by chronic cholecystitis and under suspicion of neoplasia of the cholecyst, came studied and subordinated to cholecystectomy approximately a year ago. As per William Shakespeare's comedy "Much Ado About Nothing", also in this case numerous resources have been inefficiently used and precious diagnostic tools, instead of clearing our doubts and confirming the diagnosis, perhaps due to the lack of experience and also for the fear of the medical-legal reactions, they assumed otherwise. Now, thinking about this case, makes us smile. We shouldn't forget that, in accordance with what we remember from our Masters, often the most probable pathology is also that most frequent one.

[The surgical treatment of gastric carcinoma. Evolution in surgical technique and staging in a series of 194 patients]

AIM

Surgery is, at present, the only potentially curative treatment for gastric carcinoma. The curability depends upon the extension and localization of the tumor and, particularly, the lymphatic involvement and the presence of distant metastases. The aim of this paper is to describe the personal experience during the last 2 decades and analyze the results of the surgical approach which has changed over the time.

METHODS

One-hundred and ninety-four consecutive patients have been reported (127 male and 67 female, with a median age of 65.8 years), affected by gastric carcinoma and subjected to surgical procedures from 1987 to 2000. Because of the wide period of time which it refers to, this study is overlapped by a radical change in the staging rules of gastric carcinoma, according to the publication, in 1997, of the 5th edition of the TNM. This has made necessary to divide the series into 2 different groups. The 1st group is composed of 123 patients (63.4%), staged according to TNM-1987; the 2(nd) group is composed of 71 patients (36.6%) staged according to the TNM-1997. A D1 lymphadenectomy was used as treatment protocol until 1995. Subsequently, a D2 lymphadenectomy was performed in the most part of potentially curable patients. The reconstruction after total gastrectomy was carried out in all cases with Roux technique. In distal gastrectomies a Billroth 2 technique was performed in 89.3% of the cases and a Billroth 1 technique in 10.7% of the cases.

RESULTS

The operative mortality observed on the total of patients was 1.5% (3 cases). With a median follow-up of 83 months (minimal 24, maximum 180 months), 134 patients were died, 50 are alive and 10 have been lost. The total median survival, in the 2 groups, was 24 months. We have observed a trend to improvement of survival for patients with carcinoma in stage II and III operated after 1997.

CONCLUSION

The treatment of unresectable gastric cancer, i.e. palliative surgery, is the best choice when possible in comparison to other surgical procedures (gastroenteronastomosis, jejunostomy), endoscopic procedures (dilatation, endoprosthesis, laser, percutaneous endoscopic gastrostomy) and medical therapies. In order to choose the best palliative treatment, a careful evaluation of the non-curability signs is necessary to avoid high risk surgical interventions in patients with a low expectation of life.

[Pica and intestinal occlusion: a clinical case]

Accidental or voluntary foreign bodies ingestion is a frequent reported event in emergency departments. Complication, foreign body shape related are not often observed and, once occurred, just few a cases need an open surgery approach, about 1%. The Authors report the case of a young woman with pica admitted to their Department in an emergency setting for acute intestinal obstruction due to the ingestion of not specified amount of elastics, which required an open surgery operation.

[Middle lobectomy for bronchiectasis: clinical case and review of the literature]

Over the past few years bronchiectasis, among the chronic lung diseases, has been the second most important after tuberculosis in terms of frequency and mortality. Although the incidence of the disease has been decreasing in recent years, the illness is currently of great surgical interest because of an upsurge of cases among people considered to be below the bread line. The authors present the clinical case and surgical treatment of a young adult with middle lobe bronchiectasis, with a 10-year primary IgG deficiency and severe bronchopneumonia requiring hospitalisation. Medical treatment, long regarded as the treatment of choice in this condition, has reduced the short-term morbidity of patients suffering from the disease, without affecting its ultimate mortality which is still very high today. The policy in the past to reserve surgery only for the most complicated cases or for patients not responding to medical treatment can now be considered obsolete, due to the reduced surgical risks (less than 1%) and to faster patient recovery. Further surgical indications are mono- or bilaterally located forms of the disease and failure to respond to medical treatment for more than 2 years. A review of the literature enables the authors to affirm that in the absence of randomised trials on the effectiveness of surgical vs medical treatment, it seems clear that surgical therapy is the best option, being curative and safe, with a high percentage of complete remission of disease and very low operative risks and mortality. It can therefore guarantee good quality of life, radically changing the prognosis which otherwise is fatal in 1/3 of patients suffering from this orphan disease.

[The surgery of laparoceles. The postoperative complications]

The use of prosthetic meshes in incisional hernias repairs is now very attractive, particularly for wide fascial defects; nevertheless the presence of a foreign body and placement technique may be responsible for complications sometimes leading to failure. To evaluate technical problems and complications in incisional hernia surgery the authors reviewed their 5 year experience in 70 patients; 39 mesh repairs and 31 direct sutures of the abdominal wall were performed. Local complications (fistulas, wound hematoma or infections) were more frequent in the former group; PTFE meshes showed a lower resistance to infections, particularly in diabetics, and in three patients partial or total removal was mandatory. Prosthetic meshes showed a marked reduction of recurrences in incisional hernia surgery, but their use leads to more local complications than direct repair; the authors believe that mesh placement must be evaluated for every single patient and not used as a routine procedure.

[Ambulatory phlebectomy. Literature review and personal experience]

Outpatient varicose veins surgery, "Phlébectomie Ambulatoire" (FA) introduced by R. Muller in 1966, is now a widespread technique; modified by many authors with personal tips, FA enables most lower limb varicosities to be treated on an outpatient basis and under local anaesthesia. To achieve good functional results, an accurate preoperative diagnostic examination is mandatory; the authors present a review of the indications of FA and their personal experience. Precision in performing micro-incisions, accurate dissection of the varicosities in the subcutaneous tissue and an adequate postoperative elastic bandage guarantee good aesthetic results. At present the treatment of Saphena magna with FA is debated, but some authors have already reported encouraging results.

[Abdominal carcinoid: various locations and clinical course]

Carcinoid tumours are rare neoplasms and their behaviour seems to change with the localization; in fact, appendiceal and rectal carcinoids show a better long-term survival than the more aggressive ileal and colonic analogues. The Authors report their experience in the surgical treatment of 13 G.I. carcinoid neoplasms, in which the clinical course was sometimes unpredictable suggesting there is much to discover about the behaviour of these particular tumours.

Transgastric drainage of pancreatic fluid collections

Eight pancreatic fluid collections in seven patients were successfully drained percutaneously through a transgastric approach. The drainage catheters were left in place for 3-6 weeks to promote the formation of a fistulous tract between the stomach and the pancreatic collection. Computed tomography (CT) was used for diagnosis and for planning of the access route. Combined sonography and fluoroscopy were used for guidance. Radiologic follow-up examinations (CT and sinograms) have shown no recurrences (3-12 months). No complications were encountered.

Resolution and reconstitution of Rhodospirillum rubrum pyridine dinucleotide transhydrogenase. Proteolytic and thermal inactivation of the membrane component

Pyridine dinucleotide transhydrogenase of the Rhodospirillum rubrum chromatophore membrane was readily resolved by a washing procedure into two inactive components, a soluble transhydrogenase factor protein and an insoluble membrane-bound factor. Transhydrogenation was reconstituted on reassociation of these components. The capacity of the membrane factor to reconstitute enzymatic activity was lost after proteolysis of soluble transhydrogenase factor-depleted membranes with trypsin. NADP+ or NADPH, but neither NAD+ nor NADH, stimulated by several fold the rate of trypsin-dependent inactivation of the membrane factor. Substantial protection of the membrane factor from proteolytic inactivation was observed in the presence of Mg2+ ions, an inhibitor of transhydrogenation, or when the soluble transhydrogenase factor was bound to the membrane. Coincident with the loss of enzymatic reconstitutive capacity of the membrane factor was a loss in the ability of the membranes to bind the soluble transhydrogenase factor in a stable complex. The membrane component was inactivated by preincubating soluble transhydrogenase factor-depleted membranes at temperatures above 45 degrees. NADP+, NADPH, or Mg2+ ions, but neither NAD+ nor NADH, protected against inactivation. These studies indicate that (a) the binding of NADP+ or NADPH to the membrane factor promotes a conformational alteration in the protein such that its themostability and susceptibility to proteolysis are increased, and (b) the inhibitory Mg2+ ion-binding site resides in the membrane component.