High-Precision Half-Life Measurements for the Superallowed ß

Precision measurements of superallowed Fermi ß-decay transitions, particularly for the lightest superallowed emitters ^{10}C and ^{14}O, set stringent limits on possible scalar current contributions to the weak interaction. In the present work, a discrepancy between recent measurements of the ^{10}C half-life is addressed through two high-precision half-life measurements, via γ-ray photopeak and ß counting, that yield consistent results for the ^{10}C half-life of T_{1/2}=19.2969±0.0074 s and T_{1/2}=19.3009±0.0017 s, respectively. The latter is the most precise superallowed ß-decay half-life measurement reported to date and the first to achieve a relative precision below 10^{-4}. A fit to the world superallowed ß-decay data including the ^{10}C half-life measurements reported here yields b_{F}=-0.0018±0.0021 (68% C.L.) for the Fierz interference term and C_{S}/C_{V}=+0.0009±0.0011 for the ratio of the weak scalar to vector couplings assuming left-handed neutrinos.

Production cross-sections of 181-186Re isotopes from proton bombardment of natural tungsten.

Cross-sections for the production of (181)Re, (182m)Re, (182g)Re, (183)Re, (184)Re, and (186)Re from proton bombardment of natural tungsten have been measured using the stacked foil technique for proton energies up to 17.6 MeV. Results are compared with the theoretical excitation functions as calculated by the EMPIRE II code (version 2.19) and experimental literature values. Results are in strong agreement with some of the previously reported literature as well at theoretical calculations for multiple reactions providing for more reliable estimates for the (186)W(p,n)(186)Re reaction.

Percutaneous management of unstable pelvic ring disruptions.

Percutaneous pelvic fixation stabilizes pelvic ring disruptions without extensive pelvic dissection. For this reason, these anterior and posterior percutaneous pelvic fixation techniques allow acute and definitive treatment. Successful percutaneous pelvic fixation techniques depend on accurate closed reduction, excellent intraoperative fluoroscopic imaging, and detailed preoperative planning. Early pelvic stability diminishes haemorrhage, provides patient comfort, and allows early patient mobilization from recumbency.

Plantar-flexion tarsometatarsal joint injuries in children.

We are reporting a series of eight patients ranging in age from 3 to 10 years who sustained plantar-flexion injuries of the foot, resulting in injuries to the tarsometatarsal (TMT) interval. All injuries were identified within 3 days and treated with molded short leg immobilization. We evaluated all patients an average of 32 months after injury with physical examination and the Midfoot Functional Rating (MFR) score. Seven patients had no limitations in their activities of daily living or athletic endeavors. These seven patients had MFR scores of 100. One patient had complaints of midfoot pain with running for >5 min and radiographic evidence of degenerative changes across the TMT interval at 3-year follow-up. These results suggest that although indirect pediatric TMT injuries have a generally favorable prognosis, early degenerative changes can occur and may be responsible for chronic pain and activity limitation. Degenerative changes in this weight-bearing region in a young patient can have lifelong implications. Patients and parents may benefit from discussion of the potential for future midfoot compromise following this injury.

Results of anterior cruciate ligament reconstruction in the adolescent female.

This study evaluated the functional results and complications of anterior cruciate ligament (ACL) surgery in adolescent females. We studied 22 consecutive female patients younger than 20 years who underwent arthroscopic ACL reconstruction. Average follow-up was 31 months. One hundred percent of the patients were satisfied. Seven patients returned to intercollegiate or high school sports. The mean Lysholm score was 94, and the International Knee Documentation Committee score was 40% normal, 60% nearly normal. KT-1000 arthrometer side-to-side differences were

Dislocation of the knee with lateral dislocation of the patella. A report of four cases.

In a group of 25 patients with traumatic dislocation of the knee, four, all of whom had similar ligament and medial soft-tissue injuries, also had associated lateral patellar dislocation. In all four reconstruction was delayed because of their other serious injuries. Having encountered the combination of knee dislocation and lateral patellar dislocation in 16% of our patients, we believe that it may be less rare than is commonly believed. We think that it is important to maintain a high index of suspicion of possible patellar dislocation when medial structures have been severely damaged. Early recognition and immobilisation in extension can prevent fixed lateral dislocation of the patella.

Percutaneous fixation of pelvic ring disruptions.

Percutaneous pelvic fixation is possible because intraoperative fluoroscopic imaging and other technologies have been refined. Anterior and posterior unstable pelvic ring disruptions are amenable to percutaneous fixation after closed manipulation or open reduction. Stable and safe fixation is achieved only after an accurate reduction. Anterior pelvic external fixation remains the most common form of percutaneous pelvic fixation; however, percutaneously inserted medullary pubic ramus, transiliac, and iliosacral screws stabilize pelvic disruptions directly while diminishing operative blood loss and operative time. These percutaneous techniques do not decompress the pelvic hematoma allowing early definitive fixation without the risk of additional hemorrhage. Complications associated with open posterior pelvic surgical procedures are similarly avoided by using percutaneous techniques. A thorough knowledge of pelvic osseous anatomy, injury patterns, deformities, and their fluoroscopic correlations are mandatory for percutaneous pelvic fixation to be effective.

Somatosensory evoked potential monitoring during closed humeral nailing: a preliminary report.

OBJECTIVES: To assess the role of intraoperative somatosensory evoked potential (SSEP) monitoring of the radial and median nerves in preventing iatrogenic nerve injury during closed, locked intramedullary (IM) nailing of the humerus. DESIGN: Prospective clinical study. SETTING: Pacific Northwest Level One trauma center and Southern California military medical center. PATIENTS: Thirteen patients with indications for surgical stabilization of fractures of the humeral diaphysis and either unknown neurologic status of the affected limb or anticipated difficult reduction maneuvers due to fracture complexity or displacement. INTERVENTION: Closed, antegrade or retrograde locked IM nailing of the humerus was attempted while intraoperative monitoring of the radial and median nerves with SSEP was performed. MAIN OUTCOME MEASUREMENTS: Intraoperative radial and median nerve SSEP changes during closed fracture manipulation, guide rod insertion, reaming, and humeral nail placement. RESULTS: Baseline recordings were obtained in twelve of thirteen patients for both the radial and median nerves. An absence of radial nerve signal in one patient with a closed head injury prompted an open procedure, revealing entrapment of the radial nerve in the fracture. Intraoperative SSEP changes were observed in two of the twelve remaining patients during fracture manipulation and distal interlocking. The signal amplitude returned after discontinuation of manipulation and traction, and alteration of the interlocking maneuver. No neurologic deficits were noted in these two patients. CONCLUSIONS: Intraoperative radial nerve SSEP monitoring appears to reliably reflect the status of the radial nerve in those patients with a humerus fracture. In three of eleven patients, intraoperative signal changes prompted a change in surgical plan. In no patient did there appear to be evidence of iatrogenic nerve injury.

Levels of high energy phosphate in the dorsal skin of the foot in normal and diabetic adults: the role of 31P magnetic resonance spectroscopy and direct quantification with high pressure liquid chromatography.

Determining viability of tissues and wound-healing potential in diabetic patients remains a significant challenge. Current methods for preoperative assessment of wound-healing potential (pressures in the ankle, temperature of tissues, transcutaneous measurements of oxygen, and systemic nutritional status) are indirect, in that they characterize the delivery of oxygen or other nutrients to the cells. A noninvasive means to measure adenosine triphosphate (ATP) and phosphocreatine (PCr), the fundamental high energy phosphate substrates of oxidative energy-metabolism in the skin, has been devised by using magnetic resonance spectroscopy (MRS). The signal-to-noise ratio of bioenergetic metabolites in the skin was 86% lower in five patients with diabetes who had ischemia of the lower extremity compared with five control subjects (P < 0.0001), suggesting that the concentration of high energy metabolites in diabetic patients was reduced. The ratio of ATP/phosphocreatine (PCr) in patients with diabetes was also significantly lower than in controls (P < 0.01). Chewing a single piece of nicotine gum reduced the measured concentrations of ATP and PCr in control subjects by an average of 18% and by an average of 75% in subjects with diabetes. To verify these results in a second experiment, skin was harvested from the surgical wound sites in eight patients with diabetes undergoing elective amputation, eight patients with diabetes undergoing elective foot surgery, and ten age-matched control (nondiabetic) patients undergoing elective foot surgery. Analysis of ATP and PCr using high pressure liquid chromatography corroborated MRS findings, showing a significant reduction in ATP and PCr in diabetic skin. Depression of metabolites was more severe in the patients with diabetes undergoing amputation than in the ones undergoing elective surgery. Results demonstrate depression of metabolites in the skin of patients with diabetes and suggest that MRS with 31p may be useful in characterizing metabolites in the skin.

Abduction stress and AP weightbearing radiography of purely ligamentous injury in the tarsometatarsal joint.

Twenty volunteers (40 feet) with no prior foot injury underwent standardized abduction stress and standing AP radiographs. Subsequently, the Lisfranc and dorsal tarsometatarsal ligaments in nine feet from cadavers were sectioned in a varying sequential manner, and interval standardized radiographs of abduction stress and AP simulated weightbearing were obtained. On abduction stress radiographs in 39 of 40 feet of volunteers and nine of nine feet of cadavers before sectioning, a line tangential to the medial aspect of the navicular and medial cuneiform (medial column line) intersected the base of the first metatarsal. Combining the sectioning of the Lisfranc and dorsal tarsometatarsal ligaments produced a disruption of the medial column line in all feet from cadavers. Disruption of this medial column line may be a simple and valuable diagnostic tool for determining significant ligamentous injury to the tarsometatarsal interval.

Iliosacral screw fixation: early complications of the percutaneous technique.

OBJECTIVE: To report on the early complications related to the percutaneous placement of iliosacral screws for the operative treatment of displaced posterior pelvic ring disruptions. STUDY DESIGN: Prospective, consecutive. SETTING: Level-one trauma center. PATIENTS: One hundred seventy-seven consecutive patients with unstable pelvic ring fractures. One hundred two male and seventy-five female patients ranging in age from eleven to seventy-eight years (mean, thirty-two years). INTERVENTIONS: Operative procedures were performed urgently according to the patient's clinical condition. Anterior pelvic reductions and fixations were performed by using internal and external fixation techniques. Accurate closed or open reductions of the posterior pelvic ring disruptions were accomplished by using a variety of surgical techniques dependent on the specific pattern of pelvic ring disruption. Closed manipulative reductions of the posterior pelvic ring were attempted for all patients. Open reductions were necessary in those patients with unacceptable closed manipulative reductions as assessed fluoroscopically at the time of operation (more than one centimeter in any field of fluoroscopic imaging). MAIN OUTCOME MEASURES: Plain inlet and outlet radiographs were obtained postoperatively at six weeks, three months, and twelve months. A pelvic computed tomography scan was performed postoperatively to assess fracture or dislocation reduction and the implant safety. Annual follow-up pelvic radiographs were obtained. Residual pelvic deformities were quantified based on these imaging modalities. RESULTS: There were no posterior pelvic infections. Minimal blood loss was associated with this technique. Complications occurred due to inadequate imaging, surgeon error, and fixation failure. Fluoroscopic imaging was inadequate due to obesity or abdominal contrast in eighteen patients. Five screws were misplaced due to surgeon error. One misplaced screw produced a transient L5 neuropraxia. Fixation failures related to either crandiocerebral trauma, delayed union, noncomplicance, and a deep anterior pelvic polymicrobial infection secondary to a urethral tear occurred in seven patients. There were two sacral nonunions that required debridement, bone grafting, and repeat fixation prior to healing. CONCLUSIONS: Iliosacral screw fixation of the posterior pelvis is difficult. The surgeon must understand the variability of sacral anatomy. Quality triplanar fluoroscopic imaging of the accurately reduced posterior pelvic ring should allow for safe iliosacral screw insertions. Anticipated noncompliant patients or those with craniocerebral trauma may need supplementary posterior pelvic fixation. Low rates of infection, blood loss, and nonunion can be expected.

Orthopaedic manifestations of invasive group A streptococcal infections complicating primary varicella.

The incidence of invasive group A streptococcal (GAS) infections in primary varicella appears to be increasing. GAS infections complicating varicella range from cellulitis, abscess, and septic arthritis to life-threatening necrotizing fasciitis and pyomyositis in association with GAS toxic shock syndrome (TSS). Four patients admitted in 1 year to the Children's Hospital and Medical Center in Seattle, whose care included evaluation and treatment by the Orthopaedic service, are presented to illustrate this spectrum. Three had a delay in diagnosis, including discharge from previous emergency department visits. One patient with polyarticular septic arthritis was treated with diagnostic aspiration and intravenous antibiotics. The remainder required urgent surgical debridement for treatment of deep infection. Patients with necrotizing fasciitis or pyomyositis had life-threatening complications of TSS, including hypotension, adult respiratory distress syndrome (ARDS), coagulopathy, and acute renal failure. These patients required aggressive fluid resuscitation and prolonged intensive care unit support. Diagnostic imaging studies were obtained in one patient with necrotizing pyomyositis but may have served only to delay definitive treatment. Recognition of the potential for secondary GAS infections and a high index of suspicion for the presence of necrotizing soft-tissue infection are essential in the evaluation of any child with fever and localized extremity pain with varicella.

Fatal group A streptococcal infection with toxic shock syndrome: complicating minor orthopedic trauma.

Since 1987, reports have appeared of a streptococcal toxic shock syndrome in various clinical settings. None have appeared in the orthopaedic literature. Between 1989 and 1991 at our institution three patients with relatively minor orthopaedic injuries or procedures died of group A streptococcal infections complicated by toxic shock syndrome. The manifestations of this syndrome included rapid progression of systemic sepsis, necrotizing soft-tissue infections, acute renal failure, adult respiratory distress syndrome, and coagulopathy. All three patients died despite aggressive resuscitative measures and surgical debridement. Optimal treatment of this life-threatening process requires early recognition, aggressive surgical debridement, appropriate antibiotic management, and intensive care unit support.

Lateral approach to the humeral shaft: an alternative approach for fracture treatment.

Indications for operative treatment of fractures of the shaft of the humerus have been well described. Anterolateral and posterior surgical approaches are generally preferred for fractures of the proximal/middle thirds and distal third of the humerus, respectively. Each approach has its advantages and disadvantages. We present an alternative, "lateral" approach to the humeral shaft. This approach allows supine positioning of the multiply injured patient and visualization of the radial nerve throughout the extent of the incision, and requires no muscle splitting.

Effects of the Iditarod Sled Dog Race on serum thyroid hormones and body composition.

Cold exposure, activity and energy deficit have been associated with changes in body composition and/or changes in serum thyroid hormones. Because these conditions are present during the Iditarod Sled Dog Race, 10 volunteer participants were studied before and after the race. Body composition, total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3), and free triiodothyronine (FT) levels were determined. There was a significant decrease in body weight (p < 0.05) and a decrease in body fat (p < 0.01). There were no significant changes in TT4, FT4, TT3 or FT3. On the basis of this study, it can be concluded that the strenuous activity of the Iditarod mitigates against the classic perturbation in thyroid axis brought on by the hypocaloric state.