How have alternative bearings (such as metal-on-metal, highly cross-linked polyethylene, and ceramic-on-ceramic) affected the prevention and treatment of osteolysis?

Osteolysis is a multifactorial process dependent on surgical technique, implant design, patient factors, and material composition. Alternative bearing surfaces, such as highly cross-linked polyethylene, ceramic-on-ceramic, and metal-on-metal articular surfaces, have been introduced in an attempt to reduce wear and osteolysis following total hip arthroplasty. Intermediate-term follow-up data available suggest that the prevalence and severity of osteolysis may be reduced with these materials compared with conventional metal-on-polyethylene bearing surface couples. However, long-term data are presently unavailable; the future performance of these bearings awaits clinical validation.     

Modulation of allograft incorporation by continuous infusion of growth factors over a prolonged duration in vivo

Morselized cancellous allograft bone is frequently used in the reconstruction of bone defects in cases of revision total joint replacement, trauma, spine fusion and treated infection. However, the initial lack of viable bone cells in morselized allograft bone significantly slows the process of graft incorporation compared to autograft bone. This study examined the effects of prolonged local infusion of the growth factors bone morphogenic protein-7 (BMP-7 or OP-1) and fibroblast growth factor-2 (FGF-2 or basic FGF) in the process of allograft incorporation using a rabbit tibial chamber model. New bone formation was evaluated by two indices, the activity of alkaline phosphatase and the level of birefringence. The markers of osteoclast-like cells were also measured. Without the infusion of the growth factors, lower levels of new bone formation were observed in the allograft group, compared to the autograft group. Infusion of growth factors FGF-2 and OP-1, singly or in combination, for 4 weeks, diminished this difference. The numbers of osteoclast-like cells were much higher in the allograft group before the growth factors were delivered. The infusion of FGF, singly, diminished this difference. However, the infusion of OP-1 or the combination of FGF and OP-1 did not decrease the number of osteoclast-like cells to a level comparable to autograft only. Local infusion of growth factors appears to be a useful adjunct to promote the incorporation of allograft bone in vivo.     

磁性明胶微球体内分布实验研究

对磁性明胶微球进行了同位素标记。用γ-闪烁照相技术观察了磁性明胶微球在兔体内的分布。结果表明:靶部位的放射活性加磁场是未加磁场的15倍,而且施加磁场时间长和磁场强度大有利于磁性明胶微球定位于靶区。文中也介绍了自行设计的外加磁场装置。     

Pediatric lung transplantation for pulmonary hypertension and congenital heart disease.

Five children underwent lung transplantation for end-stage pulmonary hypertension and respiratory insufficiency associated with congenital heart disease. One (17 mo) had pulmonary hypertension with a patent ductus arteriosus and required two periods of preoperative extracorporeal membrane oxygenation before successful bilateral sequential lung transplantation. One (21 mo) required bilateral lung transplantation for pulmonary hypertension and bronchopulmonary dysplasia associated with iatrogenic injury to the left pulmonary artery. This child also had patent ductus arteriosus ligation and preoperative catheter closure of an atrial septal defect. Extracorporeal membrane oxygenation was required for early postoperative pulmonary support. One child underwent right single-lung transplantation and closure of an atrial septal defect for pulmonary hypertension. Two patients had single-lung transplantation for Eisenmenger's syndrome: 1 with muscular inlet ventricular septal defect closure, atrial septal defect closure, and right single-lung transplantation; 1 with ventricular septal defect closure, patent ductus arteriosus ligation, right ventricular outflow tract patch repair, and single-lung transplantation. All patients survived operation, with one late death (lymphoproliferative disease). The 4 survivors are all ambulatory without oxygen and have evidence of normal pulmonary artery pressure 9 to 12 months after transplantation.     

Trabecular bone architecture in female renal allograft recipients-- assessed by computed tomography

BACKGROUND: Osteopenia with decreased bone mineral density (BMD) is a frequent finding in renal allograft recipients. Data concerning the bone architecture in these patients do not exist, however. METHODS: We compared the bone architecture of 33 randomly assigned women (age 49 +/- 12 years), who had received renal allografts 5.6 +/- 5.3 years before the investigation, with 74 women (age 50 +/- 14 years) who were admitted for osteodensitometry. All patients underwent single-energy computed tomography (SEQCT) and a midvertebral high-resolution tomography with computer-assisted analysis of the trabecular vertebral body architecture. RESULTS: Progressive alteration of bone architecture was associated with increasing vertebral height loss of the vertebral body. Height reduction of a vertebral body of more than 15% was associated with a significantly lower BMD (-2.3 +/- 0.8 versus -1.1 +/- 1.1 standard deviations below normal BMD), a lower trabecular bone area (13 +/- 8% versus 42 +/- 22%) and a lower trabecular diameter (1.4 +/- 0.5 mm versus 2.2 +/- 0.8 mm) compared to recipients without height reduction. In comparison to a matched group of patients with similarly reduced BMD (1.1 +/- 1.2 versus 1.2 +/- 1.1 SD below normal BMD), renal allograft recipients showed a lower number of trabecular plates (5.6 +/- 3.1 versus 7.0 +/- 3.7) and a smaller intertrabecular surface (54 +/- 116 mm versus 75 +/- 138 mm). CONCLUSIONS: Alterations of bone architecture in renal allograft recipients were associated with progressive vertebral height loss. Despite similar bone mineral density, differences of bone architecture could be observed between renal allograft recipients and patients with osteoporosis.      

Lung transplantation in children following treatment for malignancy.

BACKGROUND: End-stage lung disease is a rare complication of treatment for hematologic and solid tumors in children. When present, it is generally progressive, resulting in the patient being cured of cancer only to die of respiratory failure. Lung transplantation is believed by some to be of overly high risk in this population because of the pre-existing malignancy as well as the presumed compromised immune status. METHODS: Six children (Group 1), aged 5 to 17 years (mean 12.4 years), underwent lung transplantation at our institution because of either pulmonary fibrosis or bronchiolitis obliterans following treatment for acute leukemia (n = 5) or medulloblastoma (n = 1). All patients received chemotherapy, radiation and bone marrow transplantation in the course of treatment for their malignancies. The average forced expiratory volume in 1 second (FEV(1)) was 16% of the predicted value and forced vital capacity (FVC) was 28% of predicted. These results were compared with a similar group of 13 patients undergoing lung transplantation at our institution during the same time interval (Group 2). RESULTS: There were 2 deaths in Group 1, 1 early and 1 late, for an overall survival of 67% at a mean follow-up of 4.02 years. There were no early and 7 late deaths in Group 2 for an overall survival of 46% at a mean follow-up of 4.8 years. The acute rejection rate in the first post-transplant year was 0.2 episode/patient in Group 1 and 1.8 episode/patient in Group 2 (p <0.01). No patient in Group 1 has developed post-transplant lymphoproliferative disease or a relapse of their primary malignancy. Two patients in Group 1 developed unusual infections-Aspergillus and Mycobacterium chelonae. No such infections occurred in Group 2. CONCLUSIONS: Although this represents a small series, we believe that patients with respiratory failure following treatment of a prior malignancy are suitable candidates for lung transplantation. Although they may have some relative protection from acute rejection episodes by virtue of an already compromised immunologic status while receiving standard immunosuppression, an increased propensity for opportunistic infection may exist.     

Central thrombi in pulmonary arterial hypertension detected by MR imaging

Differentiation of thrombi from slow flow in the pulmonary arteries, sometimes observed in the presence of pulmonary arterial hypertension, can be equivocal. Magnetic resonance (MR) imaging was performed in a patient with chronic pulmonary thromboembolism and pulmonary arterial hypertension using an electrocardiographically gated technique that allowed visualization of the pulmonary arteries at the end of diastole and multiple times during systole. These images were compared with those of a patient with primary pulmonary hypertension and those of healthy subjects. Thrombi were discrete structures, seen throughout the cardiac cycle on both the first and second spin-echo images, and decreased in signal intensity on the second image. Slow flow increased in signal intensity and changed in structure during the cardiac cycle and was seen best on the second image. MR may play an important role in excluding large central thrombi as the cause of pulmonary arterial hypertension. It is a noninvasive method for defining pulmonary arterial wall thickness and for direct visualization of chronic pulmonary thrombus.     

Effect of sterilization on the strength and cutting efficiency of twist drills

Retentive-pin twist drills were subjected to four methods of sterilization and then examined to determine possible effects on resistance to fracture, cutting efficiency, and surface condition. Sterilization methods included steam autoclave, chemical vapor autoclave, dry heat, and immersion in glutaraldehyde. Although the steam and chemical vapor groups had lower mean fracture strengths after sterilization, there was no statistically significant difference among the groups. Only the steam autoclave group showed a statistically significant loss of cutting efficiency. Scanning electron microscopic evaluation revealed that only drills sterilized by steam autoclave showed changes in the surface condition or cutting edges.     

Axial spine injuries in the current conflicts in Iraq and Afghanistan

The burden of injury to the axial skeleton has been substantial relative to the conflicts in Iraq and Afghanistan.A coordinated treatment algorithm is required that begins with the first encounter on the battlefield and continues through treatment at a facility in the continental United States. Translation of these spinal trauma classification systems to the battlefield requires that issues of expediency,operational limitations and restrictions, and personnel be addressed.Current staffing of far-forward echelons in theater may not include a spine-trained orthopaedic surgeon, neurosurgeon, or musculoskeletal specialist.The classification systems and treatment algorithms being used today were formed in the context of a civilian trauma setting. The ready availability of advanced medical imaging, sterile operating room theaters, and specialty-specific intensive care units in these civilian hospitals may make modern spinal trauma classification systems less applicable to a far-forward battlefield setting. However, efforts must be made to adapt current knowledge in the pursuit of a theater-specific, relevant pathway or philosophy of care for the spine-injured warrior, with implementation as far forward as feasible to ensure the best possible clinical outcome.