Use of hinged circular fixator constructs for the correction of crural deformities in three dogs

Abstract

These cases illustrate the value of using hinged circular fixator constructs for correction of crural angular deformities, particularly when length discrepancies of the tibia are present.

Mechanics of Supplemental Drop Wire and Half‐Pin Fixation Elements in Single Ring Circular External Fixator Constructs

“…Further, addition of supplemental fixation elements is mainly relevant to a single ring fixator for stabilizing an isolated bone segment . Stabilization of short juxta‐articular fracture or osteotomy segments may only allow placement of a single ring when applying a circular construct . and most hybrid constructs typically use only a single ring …”

“…Clinical circumstances influence appropriate implant selection of supplemental fixation elements when applying a circular or hybrid construct . Placement of a drop wire, rather than a supplemental half‐pin, would theoretically afford more optimal motion at the fracture or osteotomy gap when axial elasticity of the secured bone segments is considered beneficial to promote osseous union.…”

“…Larger diameter half or full splintage pins can also be used as fixation elements on ring components . The combined use of pins and wires as fixation elements securing the same bone segment in a circular or hybrid construct presents some theoretical concerns .…”

“…Pin loosening was a problem noted in an early clinical report where single half‐pins were used to supplement fixation wires in circular fixators in dogs . More recent reports describe effective combined use of fixation wires and half‐pins . A retrospective study evaluating circular constructs to stabilize antebrachial fractures in dogs weighing ≤5 kg found fractures stabilized with a supplemental half‐pin had significantly shorter times to union [mean (SD) of 54 (23) days] and were less likely to have ulnar resorption (1/9 fractures) than fractures in which a supplemental fixation wire was used [mean (SD) of 79 (29) days; 6/11 fractures]…”

“…The application of circular and hybrid external skeletal fixation to address traumatic, developmental, and neoplastic musculoskeletal abnormalities in dogs and cats has gained increasing acceptance over the past 2 decades. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Traditional circular and hybrid constructs utilize small diameter wires as ring component fixation elements, and the fixation wires are generally tensioned when using larger diameter rings to improve construct stiffness. 1,5,6,10,14,[18][19][20][21][22][23] Typically, 2 wires are attached to each ring, with 1 wire directly secured to each flat surface of the ring.…”