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Ring Characteristics



- Discussion:
    - available in sizes from 80 mm to 240 mm (most adults require 150 to 160 mm rings for the tibia);
    - rings should be large enough to allow at least 2-3 cm of space between the ring and skin (inorder to avoid pressure ulcerations);
           - most often the ring and skin will come into contact posteriorly;
    - rings that are too large will not support transfixing wires adequately, and osteogenesis will be impaired;
    - two rings are used on large fragments, & ring and drop post used for smaller fragments;
    - most proximal ring in tibial mounting can be an open section ring in tibial mounting can be an open section ring attached to a complete ring, allowing maximum flexion & providing two levels of fixation;

- Ring Components:
    - composite half rings
    - half rings
    - half rings with curved extremities
    - 5/8 half rings
    - foot rings;

- Ring Components:
    - threaded and telescopic rods;
    - rancho cubes:
         - allow attachment of 4.0, 5.0, or 6.0 mm half pins to the ring;
         - require use of centering sleeves between cubes and half pins;
         - hexagonal set screws fit thru threaded extremity holes to lock centering sleeves;
         - rancho drill guide and trocar are used to direct drill bits through cubes;
    - connection plate:
         - allows rings of different diameters to be connected;
         - special buckles are available to better secure a plate to a ring (rather that using standard bolts)
    - posts:
         - are used for attaching "drop wires" to the ring;
         - are used for insertion of oblique half pins;
    - paired conical washers:
         - these help compensate for a connecting rod's obliquity to the frame