Effect of experimental variables on the inertization of galvanic sludges in clay-based ceramics.

The incorporation of several industrial wastes in ceramic matrixes had been attempted as an effective low expense technique for the fixation of metallic species in usable products or simply to reduce the residue volume for further disposal. However, the dominant mechanism of the inertization process and the relevant influent parameters are still unknown, mostly due to the complexity of the systems. This work reports the effect of several processing parameters such as the mixing time, the calcination temperature and duration, the relative amount of sludge, and the physical aspect of the sample (powdered or pressed pellets) on the fixing level of relevant species (SiO2), SO4(2)-, Zn, Ni, Ca, Cu, Cr) by leaching in different media (aqueous, acetate, and citrate). Statistical tools were used to define the relevance of each experimental variable on the inertization process of the used galvanic sludge. The relative amount of sludge in the mixture, the calcination temperature and the agglomeration state of the sample were found to be the most influent parameters of the inertization process. The incipient reaction between sludge and ceramic matrix components points out for the dominance of a macro-encapsulation mechanism.

Role of the mixing conditions and composition of galvanic sludges on the inertization process in clay-based ceramics.

Hydroxide-metal sludges from electroplating industry are a potential source of environmental contamination due to their high content of heavy metals. The incorporation of these residues in a ceramic matrix can be a promising way to suppress the harmful effect of metals normally present in those sludges. This work reports the role of the mixing time between the waste and ceramic materials and of the calcination step on the fixing level of several metal-containing species (Al, Zn, Ni, Fe, Ca, Cu, Cr) after sequential leaching in different media (aqueous, acetate and citrate). A strong and/or long mixing process will promote the deagglomeration of the coarser agglomerates and then will increase the reactivity of remaining grains towards the ceramic material during the calcination. As a consequence, inertization is improved for fired samples. With non-calcined samples leaching increases as a result of increasing dispersability/availability of species.

Anterior/posterior lumbar fusion versus transforaminal lumbar interbody fusion: analysis of complications and predictive factors.

No previous study has compared the complications between anterior/posterior and transforaminal interbody fusions. We performed a retrospective analysis of 164 patients to compare the complications and associated predictive factors of the two techniques of circumferential lumbar fusion. Fifty-three had same-day anterior/posterior fusion (group 1), and 111 had transforaminal interbody fusion (group 2). Mean operating time (p < 0.0001) and hospital stay (p < 0.0001) was significantly longer for group 1 patients. Average blood loss was greater for group 1 patients (p < 0.01). Higher complication rates were found in group 1 patients (p < 0.004). Wound infection occurred more frequently in patients with adjunctive treatment (p < 0.04). Hospital stay was an independent predictor of complications in both groups. In group 1, body mass index was independently associated with complications. In group 2, both hospital stay and adjunctive treatment were predictive of complications. Transforaminal lumbar interbody fusion is the preferred technique because it is associated with shorter operating time, less blood loss, shorter hospital stay, and lower incidence of complications.

Epidemiological perspective on prophylactic pinning in patients with unilateral slipped capital femoral epiphysis.

The purpose of this review was to determine whether the literature supports in situ prophylactic pinning of the hip contralateral to a hip with a slipped capital femoral epiphysis (SCFE). Three hundred twenty-five articles on SCFE between 1931 and 1998 were reviewed. Two hundred six studies were used to establish normative data. Patients with a unilateral SCFE were 2,335 times more likely to develop a SCFE in the contralateral hip when compared to children in the general population experiencing an initial SCFE. Because a majority of these sequential SCFEs were detected and treated early, we concluded that close follow-up and not prophylactic pinning was most supported by the literature.

Anterior fusion for idiopathic scoliosis.

STUDY DESIGN: A review of the charts and radiographs of 22 patients with idiopathic lumbar, thoracolumbar, and thoracic scoliosis who underwent single-stage anterior fusion with rigid third-generation instrumentation and titanium surgical mesh implants. OBJECTIVES: To validate a new technique for scoliosis correction by assessing the initial correction of deformity, trunk shift, and rotation. Perioperative statistics as well as complications were reviewed. The maintenance of sagittal balance and rate of fusion were also determined after a minimum of 2 years' follow-up. SUMMARY OF BACKGROUND DATA: Posterior correction of scoliosis has been the preferred method of treatment since the introduction of Harrington rods. Recent advances in instrumentation and surgical techniques have allowed surgeons to approach scoliosis correction through the chest and abdomen. These new techniques must be validated before they become accepted alternatives to the standard of care. METHODS: One male and 21 female patients, aged 11-18 years, were observed for an average of 44 months. Matched-pairs t tests were used to compare pre- and postoperative curve measurements. RESULTS: Statistically significant curve improvements were seen when postoperative radiographs were compared with preoperative ones. The instrumented coronal plane curve was corrected 82%. A 65% spontaneous correction of the uninstrumented coronal plane curve was observed. Sagittal kyphosis improved 7 degrees, and apical rotation and tilt angles improved 71% and 80%, respectively. A mean loss of 4 degrees of correction was seen on final follow-up radiographs. Lumbar lordosis did not change significantly, and postoperative hyperlordosis was not detected. Ninety-six percent of all instrumented levels fused within 6 months. Although the perioperative complication rate was low, five patients (23%) had asymptomatic idiopathic retrolisthesis develop at the caudal end of the fused vertebrae. CONCLUSIONS: Accepted correction of idiopathic scoliosis can be achieved with anterior instrumented fusion alone.

Core decompression and conservative treatment for avascular necrosis of the femoral head: a meta-analysis.

Core decompression for avascular necrosis (AVN) of the femoral head continues to be a controversial procedure. Meta-analysis techniques were employed to identify 22 studies with a single surgical core decompression technique. A similar procedure identified eight studies that treated patients conservatively. The success rates for core decompression were 84%, 63%, and 29% for Steinberg stages I, II, and III, respectively. Conservatively treated patients with stage 0, I, III, and III AVN demonstrated success rates of 86%, 61%, 59%, and 25%, respectively. Chi-square analysis showed the success rate of core decompression to be statistically higher than conservative treatment for stage I hips only. Large multicenter prospective double-blinded studies with patients randomized to either core decompression or conservative treatment, then stratified by stage, cause, and bilaterality, are needed to determine the best treatment for early-stage AVN.

A cost analysis of two anterior cervical fusion procedures.

Multilevel anterior cervical discectomy and fusion (ACDF) remains a difficult problem. A recently described surgical technique for multilevel ACDF has eliminated the morbid complications associated with harvesting iliac crest bone graft (ICBG) while maintaining the advantages of using autologous bone graft. A matched-pairs t test was used to compare the estimated costs of 27 ACDFs using titanium surgical mesh, local autologous bone graft, and anterior plate instrumentation with 27 ACDFs using ICBG and plate fixation. The three variables considered were cage cost, operating time (cost), and hospitalization cost. The estimated costs for the two surgical procedures were not significantly different. Thus, the time saved by not harvesting an ICBG was comparable to the cost of the cage. Harvesting ICBG also increased the morbidity rate by 22%.

Aortic thrombosis after lumbar spine surgery.

A case of distal aortic occlusion after circumferential lumbar spine surgery is presented. The paradoxical clinical findings are discussed.

Differences in age, laterality, and Steinberg stage at initial presentation in patients with steroid-induced, alcohol-induced, and idiopathic femoral head osteonecrosis.

Comparisons between treatments and studies with regard to femoral head osteonecrosis (ON) are difficult because the demographic characteristics of the patients composing the samples vary greatly. The purpose of this investigation was to determine whether ON initiation and progression were specific for a causative agent. A group of 172 patients (245 hips) was subdivided by causative agent. Patients with alcohol-induced ON were significantly older (average age, 49 years; P = .0001), were men (97%), and presented with collapsed femoral heads (90%). Patients with steroid-induced ON averaged 39 years of age, 49% had bilateral disease, and 62% presented with a collapsed femoral head. Patients with idiopathic ON averaged 40 years of age, 35% had bilateral disease, and 55% presented with a collapsed femoral head. Given the different distributions of ON risk factors at initial presentation, it is likely that successful or unsuccessful outcomes may depend most on the sample receiving the intervention. We therefore recommend stratification of patients by causative agent, Steinberg stage at initial presentation, and presence of unilateral or bilateral disease to help clarify the effects of the various treatments for ON of the femoral head.

Fever following total knee arthroplasty.

This study investigated the incidence and clinical significance of postoperative fever in 118 consecutive patients undergoing 141 total knee arthroplasties (TKAs). A postoperative fever was recorded in 63 (66%) of 95 unilateral and 17 (74%) of 23 bilateral TKA patients. Nine of the unilateral and five bilateral TKA patients developed positive clinical or laboratory findings to explain the pyrexia. Unilateral TKA patients who experienced postoperative fever were statistically more likely to have a complication in the immediate postoperative period. None of the surgical variables examined had any predictive value on the incidence of postoperative fever. Aggressive pulmonary toilet, repeated physical examinations, and urine analysis are recommended when evaluating TKA patients with postoperative fever. Fever following TKA was common and was not necessarily a contraindication to discharge.

Degenerative conditions of the lumbar spine treated with intervertebral titanium cages and posterior instrumentation for circumferential fusion.

Thirty-five consecutive patients were evaluated at an average follow-up time of 20 months after circumferential lumbar spinal fusion. All patients had degenerative conditions of the lumbar spine and same-day anterior spinal fusion by using titanium cages packed with autograft bone and posterior instrumentation combined with a posterolateral autogenous bone graft. The purpose of this study was to determine whether anterior titanium cage placement and posterior instrumentation with autologous bone graft was a safe and efficacious procedure in patients with degenerative disease of the lumbar spine. Fusion rates, complications, pain relief, medication use, and work status were specifically analyzed. Although previous reports documented the use of this technique for trauma and tumor cases, few studies assessed clinical and radiographic results in patients with degenerative conditions of the lumbar spine. Plain radiographs were used to determine spinal fusion at each spinal level. All patients were administered preoperative and postoperative questionnaires regarding three specific clinical-outcome parameters. These consisted of pain level, medication use, and work status. Intraoperative and postoperative complications were also documented. Radiographic results showed that 61 (97%) of 63 lumbar levels undergoing an arthrodesis procedure fused either anteriorly, posteriorly, or both. Of the 35 patients in this series, 33 (94%) fused at all levels, and two did not. Substantial pain relief was reported in 46% of all patients. Thirteen (37%) patients had one or more surgical complications. Circumferential spinal fusion in patients with degenerative etiologies yields excellent radiographic fusion rates and good pain relief. The procedure is technically demanding and is associated with a high rate of complications.

An analysis of Food and Drug Administration medical device reports relating to total joint components.

A total of 1,717 total hip and 2,769 total knee medical device reports submitted to the U.S. Food and Drug Administration (FDA) from 1984 through 1993 were reviewed. A large percentage of total hip complications could be attributed to some aspect of component modularity. Cementless modular acetabular components were the single largest source of device-related complications. Fifty-six percent of total knee medical device reports (MDRs) were associated with accelerated polyethylene wear. By location, MDRs identified patellar (46%), tibial (33%), and femoral (5%) component complications. It was estimated that less than 5% of device-related complications were reported to the FDA. Based on the reports received, it was apparent that mechanical failure of components was a common and increasing cause of total joint revision.

Stingers, the Torg ratio, and the cervical spine.

We prospectively determined the risk of initial stinger experience in a group of college football players while considering the presence of cervical canal stenosis and each player's position, playing time, and body type. Prospective analysis revealed a 7.7% incidence of initial stinger experience. The average Torg ratio for all players was 0.924 +/- 0.122, with the seventh cervical level being the narrowest. Initial stinger experience depended on position played and body type. The Torg ratio did not influence initial stinger occurrence. Players who experienced multiple stingers, however, had significantly smaller Torg ratios than players experiencing only one stinger (0.75 versus 0.87). A Torg ratio of 0.70 may be a more statistically and clinically appropriate threshold for determining significant cervical stenosis and advising collegiate athletes of their risk of experiencing recurrent stingers.