11 kGy gamma irradiated demineralized bone matrix enhances osteoclast activity

Background

Demineralized bone matrix (DBM) allografts are widely used in orthopaedic clinics. However, the biological impact on its osteoinductivity after its sterilization process by gamma irradiation is not well studied. Furthermore, little is known about the relationship between residual calcium levels on osteoinductivity.

Hypothesis

We hypothesize that low-dose gamma irradiation retains the osteoinducitivity properties of DBM and causes ectopic bone formation.

Materials and methods

A randomised animal trial was performed to compare tissue and molecular responses of low-dose (11 kGy) gamma irradiated and non-irradiated human DBM at 6 weeks post-intramuscular implantation using an athymic rat model. In addition, we correlated residual calcium levels and bone formation in gamma irradiated DBM.

Results

A modified haematoxylin and eosin stain identified ectopic bony capsules at all implanted sites with no significant difference on the amount of new bone formed between the groups. Statistically significantly lower ratio of alkaline phosphatase expression over tartrate-resistant acid phosphatase and/or cathepsin K expressions was found between the groups.

Discussion

This study found that low-dose gamma irradiated DBM, which provides a sterility assurance level of 10^?6 for bone allografts, retained osteoinductivity but exhibited significantly enhanced osteoclastic activity. Furthermore, this is the first study to find a positive correlation between residual calcium levels and bone formation in gamma irradiated DBM.     

Benefits of resection for metachronous lung cancer

OBJECTIVES: The benefits of resection for metachronous lung cancer are not well described. The objective of this study was to evaluate the safety and efficacy of surgical resection for metachronous lung cancers. METHODS: We reviewed the charts of all patients who underwent a second resection for a metachronous lung cancer from July 1, 1988, to December 31, 2002. Type of resection, operative morbidity, mortality, and survival by stage were analyzed. Survival was determined by using the Kaplan-Meier survival method. All patients were pathologically staged by using the 1997 American Joint Committee on Cancer standards. RESULTS: Pulmonary resections were performed in 69 patients who had undergone a previous resection. The mean interval between the first and second resection was 2.4 +/- 2.5 years. Seventy-three percent of patients presented with stage I cancers, 9% with stage II cancers, and 17% with stage III cancers. Lobectomy and wedge resection were performed with equal frequency (42% each) for the metachronous cancers. Operative mortality for the second resection was 5.8%. The mean follow-up after the second resection was 37 months. Overall 5-year actuarial survival for the entire group after the second resection was 33.4%. CONCLUSIONS: Operations for metachronous cancers provided survival that approximated the expected survival for lung cancer. Surgical intervention should be considered as a safe and effective treatment for resectable metachronous lung cancer in patients with adequate physiologic pulmonary reserve.     

Analysis of factors affecting the spontaneous closure of a gastrocutaneous fistula

Background/purpose

Few reports have documented the rate of persistence of a gastrocutaneous fistula (GCF) after gastrostomy removal or the reason for the persistence of a GCF. The purpose of this report was to analyze a large group of pediatric patients with a persistent GCF to determine the rate of persistence and any factors that correlate with the persistence of a GCF.

Methods

This was a retrospective review of 1,042 children from The Children’s Hospital, Denver, Colorado who had a gastrostomy constructed between 1992 and 2002. The charts of all children with a persistent GCF after gastrostomy catheter removal were analyzed for correlation between 13 clinical parameters and the persistence of a GCF.

Results

There were 150 children with a persistent GCF for an incidence of 34%. Time elapsed between the creation of the GCF and removal of the gastrostomy appliance (≤8 months versus >8 months) was the only parameter that showed any correlation with persistence of a GCF (P < .05). None of the other parameters studied showed any conclusive correlation with persistence of a GCF.

Conclusions

Time was the only factor that determined whether a surgically created GCF would persist after removal of a gastrostomy appliance.     

Gastrostomy revision: incidence and indications

Background/purpose

Although quite reliable, gastrostomy may require revision. However, there are no reports in the literature specifically delineating identifiable risk factors or circumstances that lead to gastrostomy revision in children with gastrostomy. The purpose of this report was to determine the rate of revision and correlate any factors that may lead to revision.

Methods

A retrospective chart review was performed on 1,042 children who underwent gastrostomy at The Children’s Hospital, Denver, Colorado, between 1992 and 2002. Charts of children who underwent gastrostomy were reviewed for pertinent clinical factors and compared with those who required gastrostomy revision.

Results

Of the 1,042 children, who had gastrostomies, 67 revisions were required in 61 children (6%). Of the many possible factors that could have had an influence on the revision rate, only fundoplication, percutaneous endoscopic gastrostomy (PEG), migration of the gastrostomy site, and time correlated with the need for gastrostomy revision.

Conclusions

Parents should be made aware that there is a 6% chance that their child’s gastrostomy may need revision and that the need for revision may increase with PEG, initial construction before 18 months of age, and the advancing age of the gastrostomy. Surgeons should avoid placing the gastrostomy near the costal margin, making a large gastrostomy exit tract through the abdominal wall and inserting a gastrostomy into the nutritionally depleted pulmonary stressed neurologically challenged child without first attempting to improve the child’s nutritional status.     

Does Functional Mitral Regurgitation Improve with Isolated Aortic Valve Replacement?

BACKGROUND: The surgical treatment of mitral valve regurgitation (MR) at the time of aortic valve replacement (AVR) remains controversial. The purpose of this study was to evaluate the change in severity of MR following isolated AVR, and to determine survival benefit. METHODS: Between 1991 and 2001, 250 patients underwent isolated AVR; 196 patients had concomitant functional MR. Follow-up transthoracic echocardiography (TTE) was available on 107 patients, with a median of 818 +/- 752 days. Aortic valve was stenotic in 77 and regurgitant in 30 patients. RESULTS: Mean age was 67 +/- 15 years and 57 (53%) were male. Preoperative MR was trivial (1+) in 27 (25%), mild (2+) in 44 (41%), moderate (3+) in 29 (27%), and severe (4+) in 7 (7%). At follow-up TTE, MR improved by 1 or 2 grades in 48 patients (45%). Of patients with preoperative 2+ MR, 19 (43%) improved, 16 (36%) remained unchanged, and 9 (21%) worsened. Although some patients with preoperative 3+ MR exhibited improvement, 11 (38%) remained with moderate-to-severe MR. Of those with a preoperative MR of 4+, 3 (71%) improved, and 4 remained with 3-4+ MR. For patients with preoperative 1 to 2+ MR, survival at 3 years was 98% compared to 78% for those with 3 to 4+ MR (p = 0.038). CONCLUSION: Functional MR does not always improve after isolated AVR. Survival is lower for patients with preoperative 3 to 4+ MR. Moderate-to-severe MR should be repaired at the time of aortic valve surgery.     

Australian emergency doctors' and nurses' acceptance and knowledge regarding brain death: a national survey

Healthcare staff's acceptance of brain death (BD) being a valid determination of death is essential for optimized organ and tissue donation (OTD) rates. Recently, resources to increase Australian OTD rates have been aimed at emergency departments (ED) as a significant missed donor potential was discovered. A cross-sectional survey was conducted to assess Australian ED clinicians' acceptance and knowledge regarding BD. Most (86%) of the 599 medical and 212 nursing staff accepted BD, but only 60% passed a 5-item-validated BD knowledge tool. BD knowledge was related to the acceptance of BD. Accepting BD influenced attitudes toward OTD, including willingness to donate. BD acceptance and knowledge were related to education/training regarding OTD, years of experience in EDs, experience with OTD-related tasks, and increased perceived competence and comfort with OTD-related tasks. Of concern, more than half of respondents who did not pass the BD test reported feeling competent and comfortable explaining BD to next of kin; of respondents who had recent experience with this, more than a third failed the BD test. Despite being generally positive toward OTD, Australian ED clinicians do not have a sound knowledge of BD. This may be hampering efforts to increase donation rates from the ED.     

Chylotamponade: an unusual presentation of Gorham's syndrome

Gorham's Syndrome, also known as massive osteolysis or "vanishing bone disease" results from lymphangiomatosis with adjacent bone resorption. Chylothorax is a common complication in cases of mediastinal involvement. We report a case of Gorham's Syndrome presenting as chylotamponade successfully treated with pericardial drainage, early parenteral nutritional support, bilateral pleurodesis for chylous effusions, and adjuvant external beam radiation.     

Classification of proximal tibial fractures in children

Purpose  To develop a classification system for all proximal tibial fractures in children that accounts for force of injury and fracture patterns. Methods  At our institution, 135 pediatric proximal tibia fractures were treated from 1997 to 2005. Fractures were classified into four groups according to the direction of force of injury: valgus, varus, extension, and flexion–avulsion. Each group was subdivided into metaphyseal and physeal type by fracture location and Salter–Harris classification. Also included were tibial tuberosity and tibial spine fractures. Results  Of the 135 fractures, 30 (22.2%) were classified as flexion group, 60 (44.4%) extension group, 28 (20.8%) valgus group, and 17 (12.6%) varus group. The most common type was extension-epiphyseal-intra-articular-tibial spine in 52 fractures (38.5%). This study shows that proximal tibial fractures are age-dependent in relation to: mechanism, location, and Salter–Harris type. In prepubescent children (ages 4–9 years), varus and valgus forces were the predominate mechanism of fracture creation. During the years nearing adolescence (around ages 10–12 years), a fracture mechanism involving extension forces predominated. With pubescence (after age 13 years), the flexion–avulsion pattern is most commonly seen. Furthermore, metaphyseal fractures predominated in the youngest population (ages 3–6 years), with tibial spine fractures occurring at age 10, Salter–Harris type I and II fractures at age 12, and Salter–Harris type III and IV physeal injuries occurring around age 14 years. Conclusion  We propose a new classification scheme that reflects both the direction of force and fracture pattern that appears to be age-dependent. A better understanding of injury patterns based on the age of the child, in conjunction with appropriate pre-operative imaging studies, such as computer-aided tomography, will facilitate the operative treatment of these often complex fractures.     

Safety and Efficacy of Reteplase for the Treatment of Acute Arterial Occlusion: Complexity of Underlying Lesion Predicts Outcome

We evaluated both the safety and efficacy of reteplase for treatment of acute arterial occlusion as well as outcomes based on treatment of the underlying lesion. From November 2000 to February 2004, reteplase was used to treat arterial occlusions in 81 patients. Catheter-directed intrathrombus thrombolysis was performed with reteplase (0.5 units/hr) continuous infusion. Percutaneous mechanical thrombectomy (Angiojet) was performed in 61% (n = 50) of patients prior to thrombolysis. Unmasking of significant lesions resulted in endovascular intervention (39.5%), open surgical repair (24.6%), or both endovascular and surgical repair (9.8%) of the lesion. No lesion was found in 25.9% of patients. Major and minor complication rates as well as restoration of patency, limb salvage, and amputation-free survival were evaluated. Eighty-one patients received reteplase therapy (median = 10.3 +/- 5.3 units, 19.5 +/- 7.4 hr) followed by next-day arteriogram to assess thrombus removal. Technical success was achieved in 96.2% (n = 78) of cases. Kaplan-Meier life table analysis revealed overall primary patency rates of 76.3%, 60.1%, and 51.6%, at 1, 6, and 12 months, respectively. Overall amputation-free survival rates were 86.4%, 76.4%, and 69.7% at 1, 6, and 12 months, respectively. When subdivided into postlysis intervention, the lysis-only group achieved increased patency (p = 0.0143) and increased limb salvage (p = 0.0219) at 1 year compared to the lysis and endovascular intervention and the lysis and surgical groups. The 30-day complication rate was 17.3% (n = 14), with a major complication rate of 4.9% (n = 4) and a minor complication rate of 12.3% (n = 10). There were no intracranial hemorrhagic complications. Intra-arterial catheter-directed infusion of reteplase for acute lower extremity ischemia is safe and efficacious, as shown by the low risk of bleeding complications, high limb salvage rates, and low mortality rates in this study. The complexity of the lesion that is unmasked through thrombolytic therapy is a predictor of patency and limb salvage.