Effects of postfire salvage logging on deadwood-associated beetles.

In Canada and the United States pressure to recoup financial costs of wildfire by harvesting burned timber is increasing, despite insufficient understanding of the ecological consequences of postfire salvage logging. We compared the species richness and composition of deadwood-associated beetle assemblages among undisturbed, recently burned, logged, and salvage-logged, boreal, mixed-wood stands. Species richness was lowest in salvage-logged stands, largely due to a negative effect of harvesting on the occurrence of wood- and bark-boring species. In comparison with undisturbed stands, the combination of wildfire and logging in salvage-logged stands had a greater effect on species composition than either disturbance alone. Strong differences in species composition among stand treatments were linked to differences in quantity and quality (e.g., decay stage) of coarse woody debris. We found that the effects of wildfire and logging on deadwood-associated beetles were synergistic, such that the effects of postfire salvage logging could not be predicted reliably on the basis of data on either disturbance alone. Thus, increases in salvage logging of burned forests may have serious negative consequences for deadwood-associated beetles and their ecological functions in early postfire successional forests.

COVID-19: Initial experience of an international group of hand surgeons.

The emergence of the COVID-19 pandemic has severely affected medical treatment protocols throughout the world. While the pandemic does not affect hand surgeons at first glance, they have a role to play. The purpose of this study was to describe the different measures that have been put in place in response to the COVID-19 pandemic by hand surgeons throughout the world. The survey comprised 47 surgeons working in 34 countries who responded to an online questionnaire. We found that the protocols varied in terms of visitors, health professionals in the operating room, patient waiting areas, wards and emergency rooms. Based on these preliminary findings, an international consensus on hand surgery practices for the current viral pandemic, and future ones, needs to be built rapidly.

ADSA Foundation Scholar Award: Implementing waste solutions for dairy and livestock farms.

Water quality in the United States is threatened by contamination with nutrients, primarily nitrogen (N) and phosphorus (P). Animal manure can be a valuable resource for farmers, providing nutrients, improving soil structure, and increasing vegetative cover to reduce erosion potential. At the same time, application of manure nutrients in excess of crop requirements can result in environmental contamination. Concentrated animal agriculture has been identified as a significant source of nutrient contamination of surface water, nitrogen contamination of groundwater, and ammonia emission. Areas facing the dilemma of an economically important livestock industry concentrated in an environmentally sensitive area have few options. If agricultural practices continue as they have in the past, despite the significant changes in agricultural intensity and changing environmental conditions, continued damage to water resources and a loss of fishing and recreational activity are inevitable. If agricultural productivity is reduced, however, the maintenance of a stable farm economy, a viable rural economy, and a reliable domestic food supply are seriously threatened. The identification and implementation of solutions to the generation of excess manure in confined animal feeding operations are necessary to enable such agricultural operations to thrive in environmentally sensitive areas such as the Chesapeake Bay Watershed. This paper will review an innovative collaborative approach to the development of a manure and litter solutions strategy by a diverse array of potential problem-solvers.

Total elbow arthroplasty as primary treatment for distal humeral fractures in elderly patients.

We retrospectively reviewed the results of primary total elbow arthroplasty for the treatment of an acute fracture of the distal aspect of the humerus in twenty consecutive patients (twenty-one elbows) who had a mean age of seventy-two years (range, forty-eight to ninety-two years) at the time of the injury. The patients were managed between November 1982 and October 1992. The presence of rheumatoid arthritis in nine patients (ten elbows) influenced the choice of treatment. The mean interval between the injury and the total elbow arthroplasty was seven days (range, one to twenty-five days). The mean duration of postoperative hospitalization was seven days (range, four to thirteen days). The mean duration of follow-up was 3.3 years (range, three months to 10.5 years). All patients were followed for a minimum of two years or until the time of death; the duration of follow-up was less than two years for three patients who died. None of the patients were lost to follow-up. Twenty implants were intact at the latest follow-up examination. One patient had a revision total elbow arthroplasty twenty months after the index procedure because of a fracture of the ulnar component sustained in a fall on the outstretched arm. On the basis of the Mayo elbow performance score, fifteen elbows had an excellent result and five had a good result; there were inadequate data for one elbow. There were no fair or poor results. The mean arc of flexion was 25 to 130 degrees. There was no evidence of loosening on the radiographs. Postoperative complications included fracture of the ulnar component in one patient, ulnar neurapraxia in three, and reflex sympathetic dystrophy in one. The results suggest that total elbow arthroplasty can be an alternative form of treatment of a severely comminuted fracture of the distal aspect of the humerus in older patients even in the presence of rheumatoid arthritis. This procedure is not an alternative to osteosynthesis in younger patients.

Effect of the elevated-rim acetabular liner on loosening after total hip arthroplasty.

Elevated-rim acetabular liners recently were shown to be associated with improved stability of total hip prostheses in a large clinical series. However, the effect of this design on loosening remains unknown. To address this question, we reviewed the results of 5167 primary and revision total hip arthroplasties that had been performed at our institution from September 1, 1985, through December 31, 1991; 2469 of the acetabular components had an elevated-rim liner (10 degrees of elevation), and 2698 had a standard liner. Five-year follow-up data were available for 1237 hips (174 that had an elevated-rim acetabular liner and 1063 that had a standard acetabular liner). The cumulative probability of revision because of loosening of the implant was estimated as a function of time since the operation with use of the Kaplan-Meier survivorship method. The five-year probability of survival of the acetabular component was 98.8 per cent (95 per cent confidence interval, 97.9 to 99.6 per cent) for the prostheses that had an elevated-rim liner and 98.3 per cent (95 per cent confidence interval, 97.7 to 99.0 per cent) for those that had a standard liner (p = 0.87). The effect of the elevated-rim acetabular liner on the probability of revision because of loosening of the acetabular or the femoral component was analyzed for several subgroups: components inserted with cement, components inserted without cement, primary total hip arthroplasties, revision total hip arthroplasties, male patients, and female patients. With the numbers available, no significant differences were found in the probability of survival of the acetabular or the femoral component in any of the subgroups. Theoretical considerations suggest that the geometric design of the elevated-rim acetabular liner may have biomechanical characteristics that predispose the implant to early loosening. However, our initial review of the results of total hip arthroplasties after a mean follow-up period of five years (range, 0.25 to ten years) failed to demonstrate any difference in the cumulative probability of revision because of loosening of the implant. Continued surveillance is warranted and ongoing.

The elevated-rim acetabular liner in total hip arthroplasty: relationship to postoperative dislocation.

Although an acetabular component with an elevated rim is thought to improve the postoperative stability of a total hip prosthesis, the actual clinical value has not yet been demonstrated. To address this question, we reviewed the results of 5167 total hip arthroplasties that had been performed at our institution from April 1, 1985, through December 31, 1991. The prostheses included 2469 acetabular components with an elevated-rim liner (10 degrees of elevation) and 2698 with a standard liner. The cumulative probability of dislocation was estimated as a function of time since the operation with use of the Kaplan-Meier survivorship method. Forty-eight of the 2469 hips that had the elevated-rim acetabular liner dislocated within two years, compared with 101 of the 2698 hips that had the standard acetabular liner. The two-year probability of dislocation was 2.19 per cent for the hips with the elevated-rim liner and 3.85 per cent for those with the standard liner (p = 0.001). A similar trend was seen at five years; however, because of a smaller sample the difference was not significant. Increased stability at two years was also demonstrated for the hips with the elevated-rim liner when the hips were analyzed according to the operative approach, the mode of fixation, the sex of the patient, and the type of total hip arthroplasty (primary or revision). Although these data demonstrate improved stability after total hip arthroplasty when an elevated liner is used, particularly in hips that are at greater risk for dislocation of the prosthesis, the long-term effect of this elevated liner on wear and loosening remains unknown but is of considerable concern. The elevated liner deserves additional study to clarify its effect on wear and loosening.

Late correction of malunited intercondylar humeral fractures. Intra-articular osteotomy and tricortical bone grafting.

We treated three patients with malunion after comminuted intercondylar fractures of the humerus by intra-articular derotational opening-wedge osteotomy and the insertion of a tricortical iliac bone graft. Two patients required additional operations, including interposition arthroplasty and hardware removal. A mean arc of increased motion of 65 degrees was achieved in flexion and extension in two patients and a more functional arc in the third. Although this is viewed as a salvage procedure in patients who are thought to be too young for elbow arthroplasty, none of the three patients has significant pain and none has required total elbow arthroplasty after an average follow-up of 7.6 years.

Significance of incomplete release of the distal portion of the flexor retinaculum. Implications for endoscopic carpal tunnel surgery.

Endoscopic carpal tunnel release has been shown in recent studies to result in a significant number of incomplete releases of the distal aspect of the flexor retinaculum. The significance of this complication is unknown. To address this question, we measured the amount of carpal arch widening after incomplete and complete release. The mean amount of change in carpal arch width in five cadaveric hands after partial release (all but the distal 4 mm) was 0.74 mm, which was statistically significant. The mean additional change after release of the remaining 4 mm of the flexor retinaculum was 0.12 mm, which was not significant. Incomplete release of the distal 4 mm of the distal aspect of the flexor retinaculum allows carpal arch widening that is no different from that of complete sectioning of the flexor retinaculum in the cadaver limb.

The ulnar neurovascular bundle at the wrist. A technical note on endoscopic carpal tunnel release.

The boundaries of Guyon's canal have recently been redefined by a series of anatomical dissections. These showed that the confines of this space do not extend from the pisiform to the hook of the hamate, as currently accepted. The fascial roof extends radial to the hook of the hamate, which allows the ulnar neurovascular bundle to course radial to the hamate hook. The position of the ulnar nerve and artery is of particular significance for endoscopic carpal tunnel release. Most endoscopic devices are designed to divide the flexor retinaculum just to the radial aspect of the hamate hook. Utilizing cross-sectional analysis of nine cadaver specimens, we found the ulnar artery to course radial to the hamate hook in five and palmar to it in four. Therefore, the ulnar artery may be at greater risk of injury during endoscopic procedures than previously recognized.

Lumbrical muscle incursion into the carpal tunnel during finger flexion.

Carpal tunnel syndrome is one of the many so-called cumulative trauma disorders thought by some to be related to the performance of repetitive tasks in the work-place. The cause of this disorder is unknown. We have observed lumbrical muscle incursion into the carpal tunnel during finger flexion. This study was conducted to determine the amount of this incursion in normal wrists. Five cadaver upper limbs were analyzed radiographically with radiopaque markers on the flexor retinaculum and the lumbrical muscle origins in four finger positions: full extension, 50% flexion, 75% flexion, and 100% finger flexion. The lumbrical muscle origins were an average of 7.8 mm distal to the carpal tunnel in full finger extension. They moved an average of 14 mm into the carpal tunnel with 50% finger flexion, 25.5 mm with 75% flexion, and 30 mm with 100% flexion. Abnormal lumbrical muscles have been cited as a possible cause of carpal tunnel syndrome. These findings suggest that lumbrical muscle incursion during finger flexion is a normal occurrence and is a possible cause of work-related carpal tunnel syndrome.

Cigarette smoking and nonunion after ankle arthrodesis.

The relative risk of nonunion in smokers versus nonsmokers after ankle arthrodesis was determined in a case control study. Twenty-two patients were matched to 22 controls by age, sex, surgeon, surgical technique, and preoperative diagnosis. Information on duration, amount, and past history of smoking was obtained for these 44 patients. Ten of the patients were actively smoking at the time of surgery compared with four of the controls. Six of the patients had no history of smoking and six had stopped smoking before surgery. Eleven of the controls had no history of cigarette smoking and 7 had stopped smoking before surgery. The relative risk of nonunion was increased 3.75 times for active smokers. When patients did not have any known risk factors for nonunion, the risk of nonunion for smokers was 16 times the risk of nonunion for nonsmokers.

Reoperation for carpal tunnel syndrome.

Although primary carpal tunnel release is usually successful, reoperation is needed in up to 3% of patients. Common indications of reoperation are previous incomplete surgery and postoperative fibrosis. Although most patients improve after reoperation, persistent systems are likely and failure is more frequent than after primary carpal tunnel surgery. Risk factors for failure following reoperation include the presence of an active Worker's Compensation claim, pain in the ulnar nerve distribution, and the absence of abnormality on preoperative EMG.

Beamline I11 at Diamond: a new instrument for high resolution powder diffraction.

The performance characteristics of a new synchrotron x-ray powder diffraction beamline (I11) at the Diamond Light Source are presented. Using an in-vacuum undulator for photon production and deploying simple x-ray optics centered around a double-crystal monochromator and a pair of harmonic rejection mirrors, a high brightness and low bandpass x-ray beam is delivered at the sample. To provide fast data collection, 45 Si(111) analyzing crystals and detectors are installed onto a large and high precision diffractometer. High resolution powder diffraction data from standard reference materials of Si, alpha-quartz, and LaB6 are used to characterize instrumental performance.

Effects of dietary stearic acid on plasma cholesterol levels.

Dietary advice based on saturated versus unsaturated fatty acids for the purpose of controlling the plasma cholesterol level has for many years plagued the American public with unpalatable diets that are difficult to adhere to. Stearic acid, an 18-carbon saturated fatty acid, does not share the hypercholesterolemic effect of other saturated fatty acids and may be the key to more palatable diets for the cholesterol-conscious dieter in the future.

Acute pancreatitis associated with ketoprofen.

An 80-year-old man had acute pancreatitis during the fourth week of antibiotic therapy for enterococcal endocarditis and 12 days after initiation of ketoprofen therapy for osteoarthritis of the hip. Pancreatitis resolved after discontinuance of ketoprofen therapy and while continuing antibiotic therapy for endocarditis. Common causes of pancreatitis were excluded by laboratory testing. Ketoprofen may have been the cause of pancreatitis in this case; we have suggested two possible mechanisms related to prostaglandin inhibition.