Ridgeway is a high-grade gold-copper porphyry deposit (54 Mt at 2.5 g/t Au and 0.77% Cu), related to an alkalic intrusive complex of monzonitic composition. The deposit occurs within the Cadia district of New South Wales, Australia, which consists of a cluster of four Late Ordovician gold-copper porphyry deposits and two iron-copper-gold skarn deposits with a combined gold resource in excess of 574 metric tonnes (t). The deposits lie on a 7-km-long, northwest-oriented corridor of alteration and mineralization, transverse to the axis of the postulated volcanic arc.Alteration and mineralization at Ridgeway are zoned around a vertically attenuated intrusive complex of monzodioritic to quartz monzonitic composition. Distinct styles of veining and alteration are related to different intrusive phases of the monzonite complex, with the intensity of alteration and grade of mineralization decreasing from early-to late-mineral intrusions. Early-mineral intrusions are associated with intense actinolite-magnetite-biotite (calc-potassic) alteration and up to four stages of high-grade quartz-magnetite-sulfide veining. Bornite is the most abundant sulfide formed during early-stage alteration and correlates well with gold. Moderate-to weak-intensity orthoclase-biotite ± magnetite (potassic) alteration accompanies the inter-and late-mineral intrusions, this alteration being associated with chalcopyrite-and pyrite-rich quartz-orthoclase veins. Propylitic and sodic (albite-pyrite) alteration assemblages are peripheral to, and locally overprint, the potassic alteration. Phyllic alteration is restricted to the margins of late-stage faults.The fluid inclusion assemblage comprises one and two salt-bearing brine inclusions, in addition to aqueous liquid-vapor inclusions of low to moderate salinity. No low-density, vapor-rich inclusions are present, indicating that the fluids from which the quartz veins precipitated did not enter the liquid-vapor field of the H 2 O-NaCl system. The brine inclusions undergo final homogenization to liquid via halite dissolution. This phenomenon, in addition to the absence of low-density vapor inclusions, suggests that the mineralizing fluids at Ridgeway were nonboiling hypersaline brines that exsolved directly from the crystallizing magma. The presence of mineralized aplitic vein dikes and comb quartz layering are interpreted to indicate that the early and transitional stages of mineralization at Ridgeway formed at the transition between magmatic and hydrothermal conditions.

As a result of reading this article, physicians should be able to :1. Understand the rationale behind using uncemented fixation in total knee arthroplasty.2.Discuss the current literature comparing cemented and uncemented total knee arthroplasty3. Describe the value of radiostereographic analysis in assessing implant stability.4. Appreciate the limitations in the available literature advocating 1 mode of fixation in total knee arthroplasty. Total knee arthroplasty performed worldwide uses either cemented, cementless, or hybrid (cementless femur with a cemented tibia) fixation of the components. No recent literature review concerning the outcomes of cemented vs noncemented components has been performed. Noncemented components offer the potential advantage of a biologic interface between the bone and implants, which could demonstrate the greatest advantage in long-term durable fixation in the follow-up of young patients undergoing arthroplasty. Several advances have been made in the backing of the tibial components that have not been available long enough to yield long-term comparative follow-up studies. Short-term radiostereographic analysis studies have yielded differing results. Although long-term, high-quality studies are still needed, material advances in biologic fixation surfaces, such as trabecular metal and hydroxyapatite, may offer promising results for young and active patients undergoing total knee arthroplasty when compared with traditional cemented options.

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OverviewIntroductionWe describe the correct technique for measuring compartment pressure with a handheld device to diagnose compartment syndrome.Step 1: Device PreparationProper preparation of the handheld pressure monitoring device (Stryker Surgical, Kalamazoo, Michigan) is critical to ensure that the device performs appropriately.Step 2: Identification of the Compartment of InterestThe needle must be placed in the proper location to appropriately measure a compartment’s pressure.Step 3: InjectionInject saline solution from the pressure monitoring device to clear any soft tissue from the side port on the needle that could result in inaccurate pressure measurements.Step 4: Stabilization and Pressure ReadingThe pressure must reach a stable state before it is recorded; different pressure thresholds for decompression have been recommended in the literature.Step 5: Repeat MeasurementsAs mistakes can be made with any single measurement, accuracy may be improved by repeating steps 1 through 4 and averaging the results.Step 6: Additional CompartmentsAfter the reading is obtained, move on to any additional compartment(s) that need to be evaluated, repeating the steps listed above.ResultsThe handheld intracompartmental monitoring device with a side-ported needle has been shown to be extremely accurate in the laboratory.IndicationsContraindicationsPitfalls & Challenges

Cotrel/Metha casting for infantile scoliosis can be accomplished without a specialized table using commonly available equipment.