Trace mineral supplies for populations of little and large herbivores.

Copper (Cu), iron (Fe), and zinc (Zn) are essential trace minerals for the reproduction, growth, and immunity of mammalian herbivore populations. We examined the relationships between Cu, Fe, and Zn in soils, common plants, and hepatic stores of two wild herbivores to assess the effects of weather, sex, and population density on the transfer of trace minerals from soils to mammals during the growing season. Soils, grasses, woody browse, hispid cotton rats (Sigmodon hispidus), and white-tailed deer (Odocoileus virginianus) were sampled across 19 sites. Concentrations of Cu, Fe, and Zn in grasses and browse species were not correlated with concentrations of those minerals in soils sampled from the same areas. Leaves of woody browse were higher in Cu, lower in Fe, and similar in Zn when compared with grasses. Available concentrations of soils were positively related to liver Cu and Zn in hispid cotton rats, which was consistent with the short lives and high productivity of these small mammals that rely on grass seed heads. Interactions between soil concentrations and weather also affected liver Cu and Fe in deer, which reflected the greater complexity of trophic transfers in large, long-lived, browsing herbivores. Population density was correlated with liver concentrations of Cu, Fe, and Zn in hispid cotton rats, and concentrations of Cu and Fe in deer. Liver Cu was < 5 mg/kg wet weight in at least 5% of animals at two of eight sites for hispid cotton rats and < 3.8 mg/kg wet weight in at least 5% of animals at three of 12 sites for deer, which could indicate regional limitation of Cu for populations of mammalian herbivores. Our data indicate that supplies of trace minerals may contribute to density dependence of herbivore populations. Local population density may therefore influence the prevalence of deficiency states and disease outbreak that exacerbate population cycles in wild mammals.

Detecting 2009 pandemic influenza A (H1N1) virus infection: availability of diagnostic testing led to rapid pandemic response.

Diagnostic tests for detecting emerging influenza virus strains with pandemic potential are critical for directing global influenza prevention and control activities. In 2008, the Centers for Disease Control and Prevention received US Food and Drug Administration approval for a highly sensitive influenza polymerase chain reaction (PCR) assay. Devices were deployed to public health laboratories in the United States and globally. Within 2 weeks of the first recognition of 2009 pandemic influenza H1N1, the Centers for Disease Control and Prevention developed and began distributing a new approved pandemic influenza H1N1 PCR assay, which used the previously deployed device platform to meet a >8-fold increase in specimen submissions. Rapid antigen tests were widely used by clinicians at the point of care; however, test sensitivity was low (40%-69%). Many clinical laboratories developed their own pandemic influenza H1N1 PCR assays to meet clinician demand. Future planning efforts should identify ways to improve availability of reliable testing to manage patient care and approaches for optimal use of molecular testing for detecting and controlling emerging influenza virus strains.

Refracture of proximal fifth metatarsal (Jones) fracture after intramedullary screw fixation in athletes.

This study details six instances of refracture of clinically and radiographically healed fractures of the base of the fifth metatarsal after intramedullary screw fixation. Four professional football players, one college basketball player, and one recreational athlete underwent intramedullary screw fixation of fifth metatarsal fractures. The athletes were released to full activities an average of 8.5 weeks (range, 5.5 to 12) after fixation, when healing was clinically and radiographically documented. Three football players developed refracture within 1 day of return to full activity. The other three athletes refractured at 2.5, 4, and 4.5 months after return to activity. Two football players underwent repeat fixation with larger screws and returned to play in the same season. The college basketball player underwent bone grafting and returned to play in subsequent seasons. The other three athletes underwent nonoperative management and healed uneventfully over 6 to 8 weeks. On the basis of this series, we recommend that 1) screw fixation using a large-diameter screw should be given careful consideration for patients with large body mass for whom early return to activity is important; 2) functional bracing, shoe modification, or an orthosis should be considered for return to play; 3) if refracture occurs, exchange to a larger screw may allow return to play in the same season; and 4) alternative imaging should be considered to help document complete healing.

Magnetic resonance imaging as a tool to predict meniscal reparability.

One hundred six patients who underwent high field strength magnetic resonance imaging and subsequent arthroscopy of the knee were evaluated to determine the accuracy of magnetic resonance imaging in predicting meniscal tear reparability. Each scan was independently read by three examiners with varying degrees of expertise: a musculoskeletal radiologist, a senior orthopaedic surgeon, and a general radiologist. Each suspected tear was characterized by its morphologic type, maximum length, and minimum distance from the meniscosynovial junction. A prediction was then made of whether the tear was reparable. There were 115 meniscal tears noted in the 106 patients studied. The examiners' ability to correctly estimate tear type was only fair, with correct estimates made only 14% to 67% of the time. The overall correlation of the three examiners to correctly predict the method of treatment was fair. The average accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of magnetic resonance imaging in predicting meniscal reparability were 74%, 29%, 89%, 50%, and 80%, respectively; for predicting meniscectomy, these values were 69%, 68%, 75%, 90%, and 43%, respectively. There were no significant differences between the three examiners in the accuracy of their treatment predictions. The results of this study suggest that magnetic resonance imaging is only moderately reliable for the prediction of meniscus reparability. In addition, the training of the reader does not appear to significantly influence the results.

Septic arthritis of the knee following anterior cruciate ligament reconstruction: results of a survey of sports medicine fellowship directors.

To determine the incidence of joint sepsis following anterior cruciate ligament (ACL) reconstruction and the prevailing attitudes toward its treatment, we surveyed the directors of Sports Medicine Fellowship programs about their practices in treating and preventing this complication. Of the 74 surgeons surveyed, 61 (82%) responded. These 61 surgeons performed an average of 98 ACL reconstructions yearly; 31 (51 %) routinely used a drain after ACL surgery, 18 (30%) had treated an ACL infection within the past 2 years, and 26 (43%) had treated an infection within the past 5 years. There was no significant difference in the number of infections and the surgeons' case load, graft choice, or method of reconstruction. Fifty-two surgeons (85%) selected culture-specific intravenous (IV) antibiotics and surgical irrigation of the joint with graft retention as initial treatment for the infected patellar tendon autograft, and 39 (64%) chose this regimen to treat the infected allograft. For the resistant infection unresponsive to initial treatment, IV antibiotics with surgical irrigation and graft retention were also selected as the most common treatment combination for 25 (39%) of the 61 respondents. After graft removal, the earliest a revision procedure would be considered was 6 to 9 months. The results of this survey confirm the widely held belief that septic arthritis of the knee is a relatively rare complication following ACL reconstruction. Once an infection is encountered, culture-specific IV antibiotics and surgical joint irrigation with graft retention are recommended as initial treatment. Graft excision and hardware removal is considered only for those infections resistant to initial treatment and for the infected allograft.

Geometrical relationships between bone plug configuration and patellar tendon graft width.

There is a lack of information in the orthopedic literature regarding the optimal shape of the patellar and tibial bone plugs when using the central one third of the patellar tendon graft for reconstruction of the anterior cruciate ligament. Clinically, we have observed that the final bone plug and patellar tendon graft width are narrower than the intended width of the graft secondary to contouring the bone plugs to accommodate the bone tunnel. This study mathematically evaluates the relationship between the bone plug cross-sectional configuration and its influence on osseous area and patellar tendon graft width. This mathematical study was divided into three parts using accepted trigonometric and geometric methods. The first part compares the maximum cross-sectional area of four commonly used bone plug shapes: a triangle, rectangle, trapezoid, and square for 8-, 9-, 10-, and 11-mm wide bone-patellar tendon-bone grafts. Area values were calculated as a function of the radius of a circle (bone tunnel) and were compared to determine which configuration provided maximum fill of the tunnel. In the second part, the minimum tunnel diameter needed to accommodate a graft of a given width (8 to 11 mm) for each of the four bone plug shapes was calculated. In Part 3, the maximum bone plug width that would fit in a tunnel of a given diameter (8 to 11 mm) was calculated for each of the four bone plug shapes. Results from Part 1 showed a 47% increase in the area of each shape from 8- to 11-mm wide grafts. Regardless of the bone plug size or tunnel diameter, a square plug filled 64% of the area of a circle; a trapezoid, 59%; a rectangle, 51%; and a triangle, 41%. In Part 2, the minimum tunnel diameter required to accommodate a square was 4 mm greater than the desired graft width for 8- and 9-mm wide grafts, and 5 mm greater for 10- and 11-mm wide grafts. The minimum tunnel diameter needed to accommodate a trapezoidal, rectangular, or triangular-shaped bone plug was only 2 mm greater than the desired graft width. In Part 3, the maximum graft width of the trapezoid, rectangle, and triangle was 0.8 to 1.5 mm smaller (10% to 14% less) than the corresponding tunnel diameters of 8 to 11 mm. Yet, the maximum width of the square was 2.3 to 3.2 mm smaller (29% less) than the corresponding tunnel diameters of 8 to 11 mm. These results confirm our clinical observation that the actual bone plug that would fit the bone tunnel is much narrower than the intended graft width. It is recommended that a trapezoidal or rectangular bone plug be harvested as these two shapes would provide a satisfactory amount of bone (cross-sectional area) compared with a square or triangle, with less tunnel-bone plug size difference.

Effects of ketorolac and bupivacaine on recovery after outpatient arthroscopy.

The effects of intraarticular bupivacaine, systemic ketorolac, and a combination of both treatments on postoperative pain and mobilization were evaluated in 60 healthy outpatients undergoing arthroscopic knee surgery under general anesthesia. After induction of anesthesia, patients received 2 mL of either ketorolac (60 mg) or saline solution (1 mL IV and 1 mL IM). On completion of surgery, the patient's knee joint was injected with 30 mL of either 0.5% bupivacaine or saline solution, according to a randomized, double-blind protocol. Only one patient (6%) receiving both medications complained of pain on awakening, compared with seven patients receiving either bupivacaine (37%) or ketorolac (41%) alone. Postoperative fentanyl was required by significantly fewer patients receiving combined therapy (n = 4, 21%) than either bupivacaine (n = 13, 62%) or ketorolac (n = 12, 60%) alone; however, there were no significant differences among the three treatment groups in terms of perioperative pain, nausea, or sedation visual analogue scale scores. Similarly, there were no differences in the times to ambulation or discharge or in analgesic requirements at home. In conclusion, a combination of systemic ketorolac and intraarticular bupivacaine decreased analgesic requirements and pain on awakening after arthroscopic surgery. However, the use of ketorolac alone or in combination with bupivacaine offered no advantage over bupivacaine alone with respect to recovery times after outpatient arthroscopy.

Phage pattern-specific oxacillin-resistant and borderline oxacillin-resistant Staphylococcus aureus in U.S. hospitals: epidemiological significance.

For a 13-year period (1978 through 1990), oxacillin-resistant (MIC, greater than 4 micrograms/ml) Staphylococcus aureus (ORSA) strains were collected from Clinical Center (National Institutes of Health) patients and patients from five other U.S. hospitals. From Clinical Center patients, 251 of 253 isolates (99%) were bacteriophage typed as phage group III. Five other hospitals contributed 203 ORSA strains, of which 188 (93%) were group III. The group III ORSA strains predominantly included a characteristic core pattern of phages, 7/47/53/54/75/77. For the low-level (borderline) oxacillin-resistant strains (MIC, 2 to 4 micrograms/ml), amoxicillin-clavulanic acid combination (Augmentin) testing disclosed 62 hyper-beta-lactamase producers, of which 59 (95%) were of a separate, distinct S. aureus strain, with the phage pattern 92/94/96/292/D-11 (group V). Thus, ORSA and hyper-beta-lactamase producing S. aureus are distinct epidemic strains.

Effects of local anesthesia on recovery after outpatient arthroscopy.

The effects of intraarticular bupivacaine administration on postoperative pain and mobilization were evaluated in 97 healthy outpatients undergoing knee arthroscopy under general anesthesia. After completion of the operation, which was performed using a standardized general anesthetic technique, the patient's knee was injected with 30 mL of either 0.5% bupivacaine or saline solution (control), according to a randomized, double-blind protocol. Although there were no statistically significant differences in the patient's assessment of postoperative pain, patients receiving bupivacaine required significantly less opioid analgesic medication in the postoperative period. More importantly, ambulation occurred more rapidly in those patients treated with bupivacaine (versus saline solution), permitting them to be discharged earlier than the control patients (145 +/- 51 min vs 173 +/- 50 min). No adverse effects were noted after the 150-mg intraarticular dose of bupivacaine. On the day after operation, no differences in physical activity or analgesic requirements were detected between the two treatment groups. In conclusion, bupivacaine reduced the opioid requirements and facilitated earlier mobilization after knee arthroscopy without altering the patients' perception of postoperative pain.

Stimulation of craniofacial and intramedullary bone formation by negatively charged beads.

To test for their osteogenic stimulating capacity, charged beads were implanted into cranial or mandibular defects, used as an onlay on the nasal bone surface, or injected into femoral medullary cavities of young adult rats. One month later, negatively charged beads were found to have stimulated extensive bone formation resulting in closure of craniofacial defects, a new layer of bone on the nasal bone surface, and a bead-bone lattice within marrow cavities of long bones. Positively charged beads were nonosteogenic, but elicited a pronounced fibroblastic response in the craniofacial skeleton. Positively charged beads were found associated with multinucleated giant cells at all implantation sites. Uncharged beads failed to elicit formation of new bone and were associated with connective tissue that was less cellular and less organized than was seen with positively charged beads. It was concluded that beads that have ben chemically treated to confer either a negative or positive surface charge, when placed in contact with bone, evoke osteogenesis or formation of dense connective tissue, the response depending on the surface charge of the bead. The mechanism(s) by which the charged beads foster the osteogenic or fibroblastic response is not clear. The use, however, of alloplastic materials with charged surfaces in repair and augmentation of bone, and in wound repair, warrants further investigation.

A nonparallel, nonisometric synthetic graft augmentation of a patellar tendon anterior cruciate ligament reconstruction. A model for assessment of stress shielding.

The potential for a rigidly fixed synthetic graft placed in the over-the-top position to be stress shielding/stress sharing with the patellar tendon autograft was assessed in a primate model. A patellar tendon autograft was placed anatomically and tensioned at 2 pounds for all of the groups. In the augmented animals, a 30 strand braided graft 10 cm in length of expanded polytetrafluoroethylene was tightened with the knee in full extension. After 6 months of unrestricted cage activity the animals were sacrificed and biomechanical testing performed. The augmented patellar tendon autografts demonstrated less laxity in extension as compared to the autografts alone. A minimal decrease in the load and stiffness to failure for the augmented groups as compared to the nonaugmented knees was noted. However, both the reconstruction groups had a significant decrease in the load to failure at 6 months (50% of the normal ACL). In summary, this study demonstrated that a synthetic graft augmentation can be performed in the over-the-top position and minimize knee laxity, especially during terminal extension. With this technique, the laxity was minimized while the incorporation and strengthening of the biologic autograft occurred at a rate similar to the unaugmented reconstruction.

Quantification of the perfusion of the anterior cruciate ligament and the effects of stress and injury to supporting structures.

The perfusion of the normal ACL was quantitated using the hydrogen washout technique in a canine model. This was compared to the perfusion of the synovium in the suprapatellar pouch. Changes in the ACL perfusion were quantitated after the application of anterior stress, division of the infrapatellar fat pad, and dissection of the synovium enveloping the ACL. The ACL is relatively hypovascular, with one-half the blood flow of the synovium of the suprapatellar pouch. Application of an anterior stress diminishes the blood flow to the ACL to one-fifth of the baseline value, an effect which is reversible. Division of the infrapatellar fat pad causes a two-fold decrease in perfusion to the ACL, whereas dissection of the enveloping synovium results in a complete cessation of blood flow.

Measuring moment-to-moment pilot workload using synchronous presentations of secondary tasks in a motion-based trainer.

A simulation was conducted to determine whether the sensitivity of secondary task measures of pilot workload could be improved by synchronizing their presentation to the occurrence of specific events or pilot actions. This synchronous method of presentation was compared to the more typical asynchronous method, where secondary task presentations are independent of pilot's flight-related activities. Twelve pilots flew low- and high-difficulty scenarios in a motion-base trainer with and without concurrent secondary tasks (e.g., choice reaction time, time production). The difficulty of each scenario was manipulated by the addition of 21 flight-related tasks superimposed on a standard approach and landing sequence. Secondary task performance did reflect workload differences between scenarios and among flight segments within scenarios, replicating the results of an earlier study in which the secondary tasks were presented asynchronously. In addition, the choice reaction time secondary task was also sensitive to the workload of specific activities within flight segments. Workload ratings were virtually identical between this and the earlier study.

Electrical stimulation versus voluntary exercise in strengthening thigh musculature after anterior cruciate ligament surgery.

Twenty patients who had undergone anterior cruciate ligament reconstructive surgery were placed randomly and independently in an Electrical Stimulation Group (n = 10) or Voluntary Exercise Group (n = 10) to compare the effectiveness of these two muscle-strengthening protocols. Patients in both groups used simultaneous contraction of quadriceps femoris and hamstring muscles during a training regimen that consisted of either voluntary exercise or electrical stimulation trials five days a week for a three-week period within the first six postoperative weeks. After patients completed the training regimen, bilateral maximal isometric measurements of gravity-corrected knee extension and flexion torque were obtained for both groups and percentages were calculated. Results showed that patients in the Electrical Stimulation Group finished the three-week training regimen with higher percentages of both extension and flexion torque when compared with patients in the Voluntary Exercise Group (extension: t = 4.35, p less than .05; flexion; t = 6.64, p less than .05). These results indicate that patients in an electrical stimulation regimen can achieve higher individual thigh musculature strength gains than patients in a voluntary exercise regimen when simultaneous contraction of thigh muscles is prescribed during an early phase of postoperative rehabilitation.

An in vivo analysis of the effect of transcutaneous electrical stimulation of the quadriceps and hamstrings on anterior cruciate ligament deformation.

Transcutaneous electrical muscle stimulation (TEMS) has been advocated as a method to rehabilitate the postoperative ACL repaired/reconstructed lower extremity. Isolated quadriceps contraction can potentially disrupt the ACL repair/reconstruction; to minimize this risk simultaneous quadriceps and hamstring stimulation has been used. This study measured the in vivo deformation of the ACL during TEMS of the quadriceps and hamstrings. Six legs in four Rhesus monkeys were immobilized in 0 degrees, 45 degrees, and 90 degrees of flexion in neutral rotation using a Hoffman frame and pins placed through the proximal femur and distal tibia. The hamstrings and quadriceps muscles were stimulated with a dual channel electrical stimulator individually and simultaneously at each point of flexion, and ACL deformation was measured using a Hall effect device placed on the anterior medial fibers of the ACL. The following conclusions were made: 1) Isolated quadriceps contraction produces ACL elongation at 0 degrees and 45 degrees of knee flexion and produces ACL shortening at 90 degrees of knee flexion. 2) Isolated hamstrings contraction produces ACL shortening at 45 degrees and 90 degrees of knee flexion and negligible effects at full knee extension. 3) It is not possible to simultaneously contract the quadriceps and hamstrings using separate stimulator pads for each muscle group. 4) At 45 degrees of knee flexion when the quadriceps muscles are stimulated before the hamstring muscles and simultaneous contraction of both is then sustained, ACL lengthening occurs. 5) When the hamstring muscles are fired before the quadriceps muscles and simultaneous contraction of both is sustained, ACL shortening occurs.

Electrically elicited co-contraction of thigh musculature after anterior cruciate ligament surgery. A description and single-case experiment.

The purpose of this article is to describe a method for strengthening the quadriceps femoris muscle in a patient after anterior cruciate ligament (ACL) surgery. The method incorporates electrically elicited co-contraction of the quadriceps femoris and hamstring muscles. A single-case experimental design based on a split-middle (ABAB) technique was used to assess the effects of the systematic administration and withdrawal of electrical stimulation with respect to changes in knee isometric extension and flexion torque and circumferential measurements of the thigh in a patient six weeks after ACL reconstruction. Results show increases in extension and flexion torque and thigh circumferential measurements that are associated with both stimulation (treatment) phases in addition to a maintenance effect demonstrated during the withdrawal phase. In this patient, the technique appears to be effective in increasing muscle strength and circumferential measurements, particularly quadriceps femoris muscle torque. Implications and suggestions for future research are included.

Dupuytren's disease in blacks.

Dupuytren's disease in blacks is believed to be rare. Our recent experience with the disease at the John Cochran Veterans Administration Hospital in St Louis is described, including 2 black patients suffering from the condition. The literature is reviewed and some aspects of pathogenesis are discussed. It is our belief that Dupuytren's disease is more common in blacks than previously reported.

Radiostrontium clearance and bone formation in response to simulated internal screw fixation.

Changes in radiostrontium clearance (SrC) and bone formation (tetracycline labeling) were observed in the femurs of skeletally mature dogs following the various operative steps involved in bone screw fixation. Drilling, but not periosteal stripping, produced a small but statistically significant increase in SrC and endosteal bone formation in the distal third of the bone. Strontium clearance values equivalent to those produced by drilling alone were recorded after screw fixation at low or high torque (5 versus 20 inch pounds), as well as by the insertion of loosely fitting stainless steel implants. Bone formation (equals the percentage tetracycline-labeled trabecular bone surfaces) was increased by 30% when SrC values exceeded 3.5 ml/100 g bone/min, and the relationship was linear when SrC values ranged between 1.0 and 7.0 ml/100 g bone/min. The changes in SrC and bone formation one-week after bone screw application are primarily those associated with a response to local trauma caused by drilling.

Effects of standard surgical procedures on the patellar blood flow in monkeys.

The effects of various surgical dissections on the patellar blood flow were studied in ten monkeys by the use of the hydrogen washout technique. The patellar blood flow was decreased to an average of 65% of the control value after an extensive medial parapatellar arthrotomy. When the infrapatellar fat pad was completely removed following extensive medial arthrotomy, the blood flow further decreased to an average of 49% of the control. When a lateral retinacular release with sacrifice of the lateral superior genicular artery was performed following the medial arthrotomy, the blood flow decreased to an average of 53% of the control. When a lateral release was combined with removal of the fat pad following the main medial arthrotomy, the patellar blood flow showed marked decrease to an average of only 17% of the control. The vascular anatomic study demonstrated that many vessels penetrate from the fat pad into the inferior pole of the patella. It is suggested that the lateral superior genicular artery and/or the fat pad should be carefully preserved to avoid ischemia of the patella during extensive procedures such as total knee arthroplasty.

Temporoparietal craniopagus. Case report and review of the literature.

A case of craniopagus twins joined in the temporoparietal area is presented, along with a review of the literature on craniopagus. A large area of brain was shared between the neurologically normal infants, with defects in the scalp, skull, and dura. The twins were separated in a three-step procedure. First, areas of shared brain were divided and separated with silicone sheets. The second procedure consisted of the insertion of scalp expanders to allow primary skin closure. In the third procedure complete separation was performed which was complicated by severe hypotension in one infant that was due to dural sinus hemorrhage. Cerebrospinal fluid leak was the most difficult problem encountered in the postoperative period; this was treated with lumboperitoneal and ventriculoperitoneal shunts. After 2 years, one twin is neurologically normal; the other is severely developmentally delayed, possibly related to the severe hypotension experienced during the third procedure. A review of the literature on craniopagus is presented. Analysis of data in the literature suggests that the area involved in the craniopagus as well as the venous connections are closely related to survival following separation of craniopagus twins.