Chemical Cross-Linking of Anatase Nanoparticle Thin Films for Enhanced Mechanical Properties.

Titania nanoparticle-based thin films are highly attractive for a vast range of commercial applications. Although their application on polymer-based substrates is particularly appealing, the requirement of low process temperatures results in low mechanical stability. Highly crystalline anatase nanoparticles were used as the building blocks for coatings through a two-stage process. The main benefits of this method, over the more common sol-gel ones, are the relatively low temperature required for the production of metal oxide coatings, allowing the use of polymer-based substrates, and the defined crystallinity of the resulting thin films. Although in several cases moderate temperatures can be utilized for drying the films, the mechanical stability of the respective coatings remains a critical issue. In this contribution, we present a strategy to achieve network formation between TiO2 nanoparticles in a preformed thin film on the basis of the cross-linking of the functionalized nanoparticles. In the first stage, the nanoparticles were functionalized by dicarboxylic acids, concurrently leading to a stable colloidal dispersion that could be utilized for dip-coating to obtain TiO2 thin films with high homogeneity and optical transparence. During the second stage, the films were immersed in a solution of a diamine as the linker molecule, to achieve cross-linking between the nanoparticles within the film. It is demonstrated that indeed covalent bonding was realized and functional coatings with significantly enhanced mechanical properties were obtained by our strategy.

Evaluation of lumbar spine fusion. Plain radiographs versus direct surgical exploration and observation.

STUDY DESIGN: In a retrospective study, the incidence of false positive and false negative interpretation of x-rays for solid spinal arthrodesis with spinal instrumentation was evaluated in 75 patients. OBJECTIVE: To evaluate the accuracy of the interpretation of x-rays for diagnosing solid spinal arthrodesis in patients with spinal instrumentation. SUMMARY OF BACKGROUND DATA: This retrospective study compared spinal fusion, as determined by direct observation and radiographic evaluation, in 75 patients with instrumented lumbar fusions using multiple devices. The fusions included posterolateral fusions or posterolateral with interbody fusions. Autograft, allograft, and a combination of these also were used. METHODS: A single blinded examiner reviewed all x-rays immediately before the spinal hardware was removed and the fusion mass was explored by the surgeon. RESULTS: There was a positive correlation between x-rays and the observations at the time of surgery in only 68% of the patients. CONCLUSION: This study indicates that the accuracy of x-ray interpretation for spinal arthrodesis is only 68%. The L4-L5 level was the most difficult level to fuse and the most difficult to interpret using x-rays. Patients with persistent back pain, when nonmechanical causes have been ruled out, should be considered for surgical exploration of the fusion mass even if x-rays appear to indicate a solid fusion.

[MR-track pointer. A reusable device for localization during interventions]. / Der MR-Track-Pointer. Ein wiederverwendbares Instrument zur Lokalisation bei Interventionen.

PURPOSE: Development of an helpful instrument for a better planning and orientation during MR guided interventions. MATERIAL AND METHODS: We developed a reusable, sterilizable instrument that can be filled both with a solution of Gd-DTPA (1%) and with a sodium chloride solution (0.9%). The pointer has a diameter of 3 and 5 mm resp. and its length is 100-150 mm. The instrument can be combined with an interactive stereotactic tracking device. RESULTS: The MR-Track-Pointer can be fixed to the two handpieces of the integrated interactive tracking system without problems. The pointer can be seen both on T1w and T2w sequences inside and outside of the tissue. This new instrument can be interactively used for reliable planning the biopsy trajectory, planning craniotomies and identifying structures which are only visible on MR images. CONCLUSIONS: The MR-Track-Pointer is an ideal supplement for the integrated virtual tracking system. It permits a minimal invasive orientation and facilitates the exact localisation of suspect lesions in sensible regions during MR guided interventions, e.g. diagnostic biopsies and tumour resections.

Quality and outcome determination in health care and orthopaedics: evolution and current structure.

Quality health care has many definitions. Among those definitions is "care that consistently contributes to the improvement or maintenance of the quality and/or duration of life." The current evolution in health care has been fueled by three necessities frequently demanded by payers and employers: improvement in access, lowering of cost, and definition and quantification of the quality of care. This evolution has been facilitated by the so-called industrialization of medicine. This concept includes the adoption of industrial economic principles and techniques that facilitate the measurement of processes and outcomes. Quality health care is currently recognized as health care that is characterized by three elements: the use of practice guidelines or standards, the implementation of continuous quality improvement techniques, and the use of outcome determination and management. Practice guidelines demand the adoption of evidence-based principles in evaluation and care, as well as minimization of variations in evaluation and care. Continuous quality improvement seeks to determine why variations in processes of care occur and then to minimize those variations. Outcomes may be measured in terms of both very objective and very subjective variables and also on the basis of cost-efficiency. Most tools currently used to quantify outcomes, especially in orthopaedics, involve measurements of general health and of specific body part or organ system function. This evolution in health care is producing significant alterations in methods of traditional health-care delivery. The accumulating evidence indicates that these changes, although frequently unpopular, are improving the quality of health care.

Musculoskeletal applications of three-dimensional surface reconstructions.

We have applied computer programs originally developed for craniofacial surgical planning and evaluation to complex musculoskeletal problems. These computer programs reformat ordinary CT scans into black and white images of the three-dimensional osseous surfaces found in the scanned volume. These reformatted three-dimensional CT scan images increase the utility of CT scan examinations of complex osseous structures, such as the wrist, spine, hip, knee, and shoulder. The software, which operates on an unmodified commercially available CT scanner, can produce high-quality surface reconstructions from CT scan slices without operator intervention. No special knowledge of the principles used in the reconstruction methods is needed to successfully use the programs.

Regional alterations in long bone 85Sr clearance produced by internal fixation devices. Part II. Histomorphometry.

The effects of each of the surgical stages involved in compression plating on the development of cortical thinning and porosity were assessed in the intact midshaft, stress-shielded femoral segments of adult mongrel dogs 6 months postoperatively. The data were evaluated in terms of a postsurgical tetracycline-based measure of remodeling and terminal 85Sr clearance (SrC) values for the plated segments of bone. Drilling had no effect on any parameter. Screw application was associated with minimal cortical thinning (p less than 0.05), while plate fixation clearly promoted thinning (p less than 0.01) and porosity (p less than 0.05). The percentage of labeled osteons, a measure of remodeling activity, increased only after plate fixation (p less than 0.05), and the labeling patterns suggested that most osteons had formed during the first 4 postsurgical months. That none of these changes were correlated with the 6-month SrC values suggests that the development of plate-induced osteopenia involves disparate histomorphometric time constants, rather than lack of any association.

Heterotopic ossification and other perioperative complications of acetabular fractures.

Thirty-eight operatively treated fractures of the acetabulum were evaluated retrospectively for perioperative complications. Functionally significant heterotopic ossification (Brooker class III or IV) developed in 23% of those patients who did not receive adequate prophylactic irradiation or indomethacin. Irradiation and indomethacin were effective in the prevention of severe heterotopic ossification. The development of severe heterotopic ossification (class III or IV) was associated with increased time from injury to operation. We conclude that prophylaxis against heterotopic ossification is warranted to decrease the incidence of this potentially preventable complication in patients who incur significant time delays prior to surgery. Other significant complications included avascular necrosis (26%), infection (13%), and neural injury (16%). Avascular necrosis developed in one patient who did not have a documented dislocation.

Comparison of cortical and cancellous screw pull-out strengths about the posterior column and sacroiliac joint.

This study addresses the comparative pull-out strengths of cortical (4.5 mm) and fully threaded cancellous (6.5 mm) bone screws from sites about the pelvis commonly used in the fixation of posterior column acetabular fractures and sacroiliac (SI) disruptions. These sites include one from lateral to medial through the posterior column, two from posterolateral to anteromedial across the SI joint, one vertically through the sacral ala, and one vertically through the iliopubic column. Statistical analysis showed no significant difference in the force required for pull-out failure of the cortical versus the cancellous screws at any of the sites tested.

Regional alterations in long bone produced by internal fixation devices. Part I. 85Sr clearance.

We examined the effect of rigid plate application on the radiostrontium clearance of the intact canine femur at 6 months. We examined each of the component surgical steps. We calculated the clearance both for the whole bone and for each of the five transverse sections of the whole bone. Screw application, but not drilling, increased the clearance in the segment about the screw holes. Plate application produced an increase in the segment beneath the plate as well as around the screws and in the whole bone. These changes are accomplished not only by an absolute increase in clearance to the middle three segments, but by a relative diminution in clearance by the most proximal and distal segments. The histomorphometric changes in long bones following rigid plating may be accompanied by regional increases in bone blood flow.

Pull-out strengths of bone screws at various sites about the pelvis--a preliminary study.

The pull-out strength of both cortical and cancellous screws from bone at various sites about cadaveric pelves was examined. No significant differences were seen between cortical or cancellous screws at similar sites with the possible exception of the sacroiliac joint. Pull-out strengths were best correlated to the depth of bone at a particular screw hole. For practical purposes, the strongest sites are in the thick buttress of bone along the iliopubic column.

The sacroiliac joint: an underappreciated pain generator.

The sacroiliac joint itself and the specific diagnosis of sacroiliac dysfunction are both underappreciated causes of pain in the low back, the pelvis, and the proximal lower extremities. An anatomically atypical synovial joint, its extensive innervation accounts for multiple modes of pain presentation. The joint and its associated ligament complex are subjected to rather constant and significant stresses. These combined factors contribute to the body of patients who present with low-back, buttock, proximal-thigh, and groin pain. Physical examination usually is an attempt to assess for presumed abnormal motion of the sacroiliac or to provoke discomfort by stressing that joint. Nonoperative treatment is usually physical therapy, and both diagnostic and therapeutic injection of the sacroiliac joint may be employed. Surgery is a treatment of last resort. There is a lack of long-term studies that address the natural history of this problem and its treatment.

In-hospital charges associated with the treatment of adult femoral neck fractures.

A retrospective analysis of 41 adult patients treated for a femoral neck fracture was performed to determine the variables that best predict total hospital charges. The patients were treated for an isolated femoral neck fracture at our hospital from January 1993 through December 1994. There were 13 men and 28 women. The average age at the time of injury was 63 years. The average length of stay was 12.1 days, and the average total hospital charges per patient were $16,072. No physician fees were included in our analysis. Detailed multivariate regression analysis of 10 variables was performed for each patient. Stepwise linear regression analysis, which controlled for all variable (such as age at injury, number of medical illnesses, gender, and others), revealed that the strongest predictors of total hospital charges were the number of medical illnesses (P < 0.0001), age at injury (P = 0.023), length of stay (P < 0.0001), and number of complications (P = 0.0007).

Orthopedic medical malpractice: an attorney's perspective.

Orthopedic surgeons are trained to manage problems involving the musculoskeletal system. It would be helpful to identify certain procedures, anatomic areas, or issues related to the physician-patient relationship that could potentially lead to a malpractice lawsuit. Once the problems are identified, steps toward continuing education and physician awareness could be initiated. In this study, we performed a randomized nationwide survey of medical malpractice attorneys to evoke their opinion on these issues. We found that the lumbar spine was the most common anatomic area involved in orthopedic medical malpractice cases, and a physician appearing rushed and uninterested is most likely to be the subject of a lawsuit where a poor physician-patient relationship was a contributing factor. Educational and professional programs are needed to increase the awareness and knowledge of orthopedic malpractice risks, and also to identify potentially preventable problems leading to malpractice litigation.

Experience with a sliding screw in intertrochanteric fractures.

A retrospective study of our first year's experience with a sliding screw in intertrochanteric fractures was conducted. Forty-five patients with intertrochanteric fractures were admitted to St. Louis City Hospital in the year considered. All those who came to surgery were treated with a sliding screw. We were impressed by the ability of the sliding screw plate to adapt to the forces which, under other circumstances, cause the unstable I-T fractures to collapse or displace. The characteristics of unstable hip fractures are discussed.

Comparison of general and epidural anesthesia in patients undergoing primary unilateral THR.

One hundred ninety-five consecutive patients underwent 195 primary unilateral total hip arthroplasties between January 1988 and December 1993. Patients were divided into three groups based on the type of anesthesia utilized for their procedure. Group I consisted of 108 patients (59 women and 49 men; average age 56 years) who had general endotracheal anesthesia alone. Group II consisted of 70 patients (41 women and 29 men, average age 58 years) who had general endotracheal anesthesia with epidural augmentation intraoperatively and postoperatively. Group III consisted of 17 patients (6 women and 11 men, average age 62 years) who had epidural anesthesia only. Data were analyzed by anesthesia group to compare a variety of clinically relevant factors. No statistically significant differences among groups were noted regarding average age at surgery, the underlying diagnoses leading to joint replacement, the number of preexisting medical conditions, length of hospitalization, nonsurgical operating room time, intraoperative blood transfusions, intraoperative femur fractures, deep venous thrombosis, deep infections, death, or the prevalence of postoperative urinary tract infections. Postoperative urinary tract infections correlated with duration of Foley catheterization, but not the duration of epidural catheterization. Significant differences among anesthesia groups were observed for two factors: 1) estimated intraoperative blood loss was highest for Group I (P < .05) and was primarily a function of surgical time (P < .0001), and 2) postoperative Hemovac output (over the first and second postoperative 24-hour periods) was greatest for Group II (P < .05). Epidural anesthesia appears to be a safe modality in patients undergoing primary unilateral total hip replacement.