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.

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.

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.

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.

Functional outcome of excision of heterotopic ossification after total hip arthroplasty.

Fifty-three cases of symptomatic heterotopic ossification were evaluated after total hip arthroplasty for the specific purpose of determining the value of surgical excision without revision or other concurrent procedures. The mean followup was 3.5 years for range of motion and 7.8 years for radiographic evaluation. A statistically significant increase in range of motion was obtained for the group at final followup. The mean increase in flexion arc was 34 degrees, abduction and adduction arc was 22 degrees, and rotation arc was 21 degrees. Of the patients who underwent surgical excision of heterotopic bone solely because of pain, none had complete alleviation of symptoms. It is concluded that surgical excision of heterotopic bone results in significant improvement in functional outcome, but it cannot be expected to predictably alleviate pain. Finally, the ultimate arc of motion was better than that suggested radiographically by the Brooker classification system.

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.

Assessment of the ratio of carpal contents to carpal tunnel volume in patients with carpal tunnel syndrome: a preliminary report.

An anatomic basis for carpal tunnel syndrome (CTS) has been proposed but not confirmed; both volumetric and area studies have been used to address this issue. The authors have demonstrated that the ratio of the carpal tunnel contents (CTC) to carpal tunnel volume (CTV) provides information regarding the relative free space in the carpal tunnel as compared with canal volume alone. This study was undertaken to determine whether the CTC/CTV ratio was higher for patients with CTS than for normal subjects. Seven asymptomatic volunteers and 7 patients with symptoms of CTS underwent magnetic resonance imaging (MRI) so that the CTC/CTV ratios could be determined. Standard radiographs were analyzed to identify plain radiographic variables that differed between patients with CTS and control subjects, and no differences were found. On MRIs, however, CTC/CTV ratios were noted to be higher for patients with CTS than for matched control subjects.

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.

Biaxial total-wrist arthroplasty.

Sixty-four consecutive biaxial total wrist arthroplasties performed in 52 patients between March 1983 and June 1988 were reviewed. Fifty-seven cases involving 45 patients were followed for a minimum of 5 years or until failure. Of the remaining 7 patients, 6 had died and 1 was lost to follow-up study. For the 46 intact implants in living patients, the mean follow-up period was 6.5 years (range, 5-9.9 years). The mean patient age at operation was 58 years. The underlying diagnosis was rheumatoid arthritis in 63 cases and juvenile rheumatoid arthritis in 1 case. At follow-up evaluation, pain was reported as none in 75%, mild in 19%, moderate in 3%, and severe in 3%. Patients rated their improvement as much better in 62%, better in 30%, some improvement in 4%, and worse in 4%. Range of motion at last follow-up averaged 36 degree extension, 29 degree flexion, 10 degree radial deviation, and 20 degree ulnar deviation. Grip strength improved from 4.1 kg preoperatively to 5.9 kg at last follow-up evaluation. Pain was likewise significantly improved at 1 year and 5 years. Failures occurred in 11 cases. The causes of failure were loosening of the distal implant in 8 cases and infection, dislocation, and progressive soft tissue imbalance in 1 case each. An abnormal resting stance and distal implant subsidence (> or = to 3 mm) at 1 year were associated with implant failure at final follow-up evaluation. The Kaplan-Meier probability of survival free of revision was 83% at last follow-up evaluation

Biaxial long-stemmed multipronged distal components for revision/bone deficit total-wrist arthroplasty.

Revision total-wrist arthroplasty has a high incidence of complications. Loosening is a significant problem for the distal implant. Because of the high failure rate of single-pronged distal implants after revision total-wrist arthroplasty, a custom multipronged distal component (biaxial total-wrist implant) was designed for use in patients with deficient bone stock who undergo revision operation. Ten cases of total-wrist arthroplasty with a custom long-stemmed multipronged distal component are presented. The preoperative diagnosis was failed total-wrist arthroplasty in 9 cases. Mean time from previous total-wrist arthroplasty to revision procedure was 5.6 years. At follow-up evaluation (mean, 3.8 years; range, 3.0-4.8 years), 2 patients had undergone arthrodesis: 1 patient at an outside institution 1 year after surgery for periprosthetic fracture of the radius, and 1 patient at our institution for distal implant loosening. The 8 other patients had functional total-wrist arthroplasties. At follow-up evaluation, all patients reported they were satisfied. Six patients reported no pain and 2 reported mild pain. Mean range of motion at follow-up evaluation was within the previously defined limits that allow patients to function in activities of daily living: 78 degrees for supination, 77 degrees for pronation, 39 degrees for extension, 17 degrees for flexion, 12 degrees for radial deviation, and 18 degrees for ulnar deviation. Revision total-wrist arthroplasty with custom long-stemmed, multipronged distal components offers an alternative to those patients with deficient bone stock who refuse arthrodesis. Early results demonstrate greater longevity compared with single-pronged components for revision total-wrist arthroplasty.

Guyon's canal revisited: an anatomic study of the carpal ulnar neurovascular space.

The boundaries of the space through which the ulnar neurovascular bundle crosses the wrist have been reinvestigated. Using gross dissections, transverse and sagittal sections, and histologic study, we determined that the roof of Guyon's canal, the "carpal ulnar neurovascular space," does not directly connect to the hamate bone, as is currently accepted. The roof of this space extends radially to the hook of hamate and attaches to the flexor retinaculum. This anatomic arrangement allows the ulnar artery and sensory component of the ulnar nerve to course radially to the hook of hamate, where they lie on the flexor retinaculum (transverse carpal ligament). The roof and radial border have three segments: (1) a proximal segment that begins near the pisiform and extends distally to the level of the hook of hamate but does not attach directly to it, (2) a central segment that contains only adipose tissue, and (3) a distal fascial layer that includes the palmaris brevis muscle. The floor of the space consists of the muscles of the hypothenar eminence, their fibers of origin, and the flexor retinaculum (transverse carpal ligament). Guyon accurately described the proximal portion of the carpal ulnar neurovascular space, but his description has been misinterpreted; the hook of hamate does not serve as the radial boundary of Guyon's canal. The anatomic relationships of the "carpal ulnar neurovascular space" need to be appreciated to avoid complications during carpal tunnel surgery.

Outcome of reoperation for carpal tunnel syndrome.

One hundred thirty-one patients with reoperation for carpal tunnel syndrome were followed for a mean of 11 years. Reoperation failed in 15 patients, necessitating a third operation. Satisfaction, symptom severity, and functional status scores were assessed with a standardized questionnaire in the other 116 patients. Patients with normal findings on preoperative nerve conduction studies, those who filed for compensation, and those who had pain in the distribution of the ulnar nerve had significantly worse results. Those with abnormal findings on nerve conduction studies who had not filed for compensation had the best symptom and function scores and satisfaction at latest follow-up examination; those with normal findings on nerve conduction studies who had filed for compensation had the poorest outcome. Although most patients were satisfied with the overall outcome, many reported residual symptoms; in addition to the 15 patients who required a third operation, 22 patients were dissatisfied with the final result.

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.

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.

Aetiology of work-related carpal tunnel syndrome: the role of lumbrical muscles and tool size on carpal tunnel pressures.

A cadaveric study was undertaken to investigate the effect of tool size and lumbrical muscle incursion on carpal tunnel pressure during active grip. Active grip was simulated by securing the specimens on an apparatus and loading each of the eight finger flexor tendons with 1 kg each. Carpal tunnel pressures were measured with and without 1- and 2-in. tubing in the hand and before and after removing the lumbrical muscles. Both variables, tool size and lumbrical muscles, were found to have a statistically significant effect on carpal tunnel pressure. Higher pressure changes were found for the 2-in. tubing, compared with 1-in. tubing, but this difference was not statistically significant.

The use of topographical landmarks to improve the outcome of Agee endoscopic carpal tunnel release.

A modified approach to endoscopic carpal tunnel release has been developed and tested in 60 cadaveric specimens by three surgeons using the Agee endoscopic carpal tunnel release system. The modified approach, which includes specific localization of the hook of the hamate, flexor retinaculum, and the superficial palmar arch utilizing topographical landmarks, avoids entry into Guyon's canal and injury to the ulnar artery and nerve, median nerve, and common digital nerves. Use of the anatomic approach resulted in significantly superior results. There were fewer incomplete releases, and fewer surgical passes were required, for the inexperienced surgeons. When these anatomic considerations were not included, the learning curve was much steeper. For surgeons planning endoscopic surgical release of the transverse carpal ligament, the described topographical approach improves the technical competence with the procedure and reduces the number of complications and learning curve associated with new procedures. We recommend the use of topographical landmarks and other anatomic considerations during endoscopic carpal tunnel release.

Externally applied forces to the palm increase carpal tunnel pressure.

Change in carpal tunnel pressures that result from externally applied forces to the palm of the hand were assessed in five cadaveric specimens. MIKRO-TIP transducers were percutaneously placed into the carpal tunnel at the level of the hook of the hamate. A 1 kg force was applied to the palm of the hand in 16 separate locations. Significant elevations in carpal tunnel pressure were observed for external forces applied over the flexor retinaculum (103 mm Hg) and also for the hypothenar (37 mm Hg) and thenar (75 mm Hg) areas adjacent to the distal aspect of the carpal tunnel. These data demonstrate that the application of external forces on the palm of cadaver hands increases carpal tunnel pressure and the magnitude of the pressure change in the carpal tunnel depends on the location of the applied force.

Effect of lumbrical muscle incursion within the carpal tunnel on carpal tunnel pressure: a cadaveric study.

Lumbrical muscle incursion within the carpal tunnel has been implicated as a possible cause of carpal tunnel syndrome. During finger flexion, surgeons have observed the presence of lumbrical muscles in the carpal tunnel. However, the significance of this incursion has not been evaluated. To evaluate the effect of lumbrical muscle incursion within the carpal tunnel as a cause of carpal tunnel syndrome, carpal canal pressures were measured in cadaver hands at the level of the hamate hook for four finger positions: (1) 100% finger flexion; (2) 75% finger flexion; (3) 50% finger flexion; and (4) full extension. After measuring carpal tunnel pressures for each position, the lumbrical muscles were excised and the pressures were again recorded. A progressive increase in carpal tunnel pressure was noted for each degree of finger flexion in the group with intact lumbricals. This is in sharp contrast to a relatively stable carpal tunnel pressure during finger flexion for the group without lumbrical muscles. Two-way repeated measures analysis of variance revealed a significant difference in carpal tunnel pressure for both variables, lumbrical muscles and finger position. One-way repeated measures analysis of variance for carpal tunnel pressures demonstrated that the effect of finger position was significant for the group with intact lumbricals but not for the group with lumbricals removed. We conclude that lumbrical muscle incursion into the carpal tunnel can result in elevation of carpal tunnel pressure in cadaver hands and could be a variable in the cause of work-related carpal tunnel syndrome.

Pressure dynamics of the carpal tunnel and flexor compartment of the forearm.

Although carpal tunnel pressures have been observed to increase as a result of repetitive flexion and extension of the wrist, and forearm compartment pressures have been shown to rise during and after muscle activity, the relationship between those two observations has not been studied. The flexor compartments of five cadavers were perfused with saline to determine whether elevated pressure in the flexor compartment of the forearm is transmitted to the carpal tunnel. The pressure in the carpal tunnel after the infusion was significantly different from the pressure in the flexor compartment of the forearm. Furthermore, pressures recorded in the carpal tunnel at the conclusion of the study were not statistically different from the preinfusion pressures. While the carpal tunnel may appear to be an open compartment anatomically, it functions as a relatively closed compartment with respect to transfer of pressure from the flexor compartment of the forearm under conditions that mimic elevated tissue pressure.