Reactions of the hydrated electron with divalent aqueous transition-metal ions, Cd(2+), Zn(2+), Ni(2+), Cu(2+), Co(2+), Fe(2+), and Mn(2+), were studied using a pulse radiolysis technique. The kinetics study was carried out at a constant pressure of 120 bar with temperatures up to 300 °C. The rate constants at room temperature agree with those reported in the literature. The reaction of Cd(2+) is approximately diffusion-limited, but none of the first-row transition-metal ion reactions are diffusion-controlled at any temperature studied. The activation energies obtained from the Arrhenius plots are in the range 14.5-40.6 kJ/mol. Pre-exponential factors are quite large, between 1 × 10(13) and 7 × 10(15) M(-1) s(-1). There appears to be a large degree of entropy-enthalpy compensation in the activation of Zn(2+), Ni(2+), Co(2+), and Cu(2+), as the larger pre-exponential factors strongly correlate with higher activation energy. Saturation of the ionic strength effect suggests that these reactions could be long-range nonadiabatic electron "jumps", but Marcus theory is incompatible with direct formation of ground state (M(+))aq ions. A self-consistent explanation is that electron transfer occurs to excited states derived from the metal 4s orbitals. The ionic strength effect in the Mn(2+) and Fe(2+) reactions suggests that these proceed by short-range adiabatic electron attachment involving breakdown of the water coordination shell.

Impending and complete pathologic fractures often necessitate surgical fixation. Traditional orthopedic implants are commonly used, achieving clinically acceptable outcomes, but their metallic composition can impair radiographic evaluation and affect radiation treatments. Recognition of these concerns led to the development of radiolucent implants such as the minimally invasive Photodynamic Bone Stabilization System (PBSS; IlluminOss Medical Inc), featuring a light cured polymer contained within an inflatable balloon catheter. Two participating hospitals in one health care system reviewed cases using the PBSS implant. Twenty-five patients with 29 impending or pathologic fractures in the proximal radius or humerus from metastatic carcinoma, myeloma, lymphoma, and melanoma were identified. Clinical charts and imaging were reviewed to determine the status of the implant at final follow-up as well as complications. For analysis, a chi-square test was used for nominal variables and a t test was used for continuous variables. Eleven of the 25 patients were alive with disease at the time of analysis. Eight of 29 (27.5%) implants failed. Five of 25 (20%) patients required repeat surgery due to complications, including 3 revision open reduction and internal fixations, 1 open reduction and internal fixation for a periprosthetic fracture, and 1 screw removal. Five of the 9 cases (56%) ( P =.03) with lesions in the distal humeral shaft had breakage of the implant by final follow-up, compared with 3 of 20 cases (15%) ( P =.03) elsewhere in the humerus; no failures were seen in the radius. One of 4 patients (25%) also had failure in the surgical neck, although this did not reach significance. Five patients were noted to have progression of disease on follow-up radiographs, with 4 failures in patients with progression. The PBSS implants potentially allow improved surveillance of fracture healing and tumor recurrence along with decreased scattering of radiation during treatment. Unfortunately, there may be a higher rate of mechanical failures, particularly for lesions involving the distal humerus. This may be due to decreased cross-sectional area of the implant in this region as compared with the metaphyseal and proximal regions. Caution should be exercised when treating distal humeral pathologic fractures with large lytic lesions where the underlying disease process is not well controlled. [ Orthopedics . 2021;44(3):154–159.]

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BACKGROUND Spine surgery has been transformed by the growth of minimally invasive surgery (MIS) procedures. Previous studies agree that MIS has shorter hospitalization and faster recovery time when compared to conventional open surgery. However, the reoperation and readmission rates between the 2 techniques have yet to be well characterized. OBJECTIVE To evaluate the rate of subsequent revision between MIS and open techniques for degenerative lumbar pathology. METHODS A total of 1435 adult patients who underwent lumbar spine surgery between 2013 and 2016 were included in this retrospective analysis. The rates of need for subsequent reoperation, 30- and 90-d readmission, and discharge to rehabilitation were recorded for both MIS and traditional open techniques. Groups were divided into decompression alone and decompression with fusion. RESULTS The rates of subsequent reoperation following MIS and open surgery were 10.4% and 12.2%, respectively (P = .32), which were maintained when subdivided into decompression and decompression with fusion. MIS and open 30-d readmission rates were 7.9% and 7.2% (P = .67), while 90-d readmission rates were 4.3% and 3.6% (P = .57), respectively. Discharge to rehabilitation was significantly lower for patients under 60 yr of age undergoing MIS (1.64% vs 5.63%, P = .04). CONCLUSION The use of minimally invasive techniques for the treatment of lumbar spine pathology does not result in increased reoperation or 30- and 90-d readmission rates when compared to open approaches. Patients under the age of 60 yr undergoing MIS procedures were less likely to be discharged to rehab.

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