Small SK™ Linear Distraction / Compression Body
Part Number 407.999

Over the years, IMEX™ has produced a number of prototype distraction/compression units. Typical requests were for either distraction osteogenesis or acute fracture reduction. The most common application was inclusion in type II fixators for repair of radial growth deformities with need for lengthening in addition to angular deformity correction. Early models were based around the then popular KE device. With the inherent weakness of KE rods, these devices frequently did not have enough strength to provide adequate stability. Use of larger rods solved many stability issues but required custom clamps since KE clamps were incompatible with the newer rods. With the availability of the SK™ ESF System by IMEX™, stronger rods are now a standard as are SK™ clamps that function with these rods. Larger rods have supported a renewed interest in a linear distraction/compression device. Our most recent version is now offered as a standard item in two sizes. It functions in the same fashion as a turnbuckle system and is designed as a modular component of the SK™ external fixator.

The body of the distraction unit is the main component and accepts partially threaded rods into each end. One end has standard, right-hand threads that accept small SK™ hybrid rods. The other end has left-hand threads that accept a special, left-handed rod. The body end with the left-hand threads is etched with an “L” to remind the surgeon that a left-handed rod is required. Left-handed rods are also etched with an “L” to avoid any confusion with standard hybrid rods, which are used in many other applications. Standard hybrid rods are available in 50mm, 75mm, 100mm, 150mm, 200mm and 250mm lengths. Left-handed rods are available in 50mm, 100mm and 150mm lengths. Both right and left-hand rod threads have a thread pitch of 1.0mm. By selecting the appropriate rod lengths for the patient anatomy and distractor body location, a custom fit assembly is produced.

In using the assembly as a distraction device, both rods are started near the middle of the body. If compression is the desired use, both rod ends are started closer to their respective body end. Distraction or compression can be achieved by turning the body with an 8mm wrench after fixator clamps and pins have been applied,. The body is clearly etched to indicate the turn direction for either compression or distraction (“close” or “open”.) Since each rod has a 1.0mm thread pitch, a complete turn of the body results in 2.0mm of distraction or compression. Smaller increments of distraction are obviously utilized on a case involving daily distractions. Do not allow the rods to be distracted too near the end of the body or be pushed out of the body when utilizing for distraction. Small windows in the body allow visualization of rod positions.

PART NO.	description
407.999	Small SK™ Linear Distraction / Compression Body
407.050L	6.3mm x 50mm Titanium Left-Handed Rod, 6mm Thread
407.100L	6.3mm x 100mm Titanium Left-Handed Rod, 6mm Thread
407.150L	6.3mm x 150mm Titanium Left-Handed Rod, 6mm Thread

Threaded portions of the rods are not locked into the holes; therefore, potential for rotational instability exists when used as a unilateral frame. In cases to date, unilateral frame lengthening applications have incorporated an IM rod. Torsional instability does not seem to be an issue with bilateral frames. Uses to date include: femoral and humeral lengthening over nail, radial lengthening with type II or type I-b ESF frame, acute fracture distraction and creative incorporation into circular ESF frames. This device does not provide the control and flexibility of a circular ESF frame but may be useful in less demanding situations.

Potential complications include all linear ESF frame complications plus potential instability, breakage of hybrid rods at threads and all complications typically associated with distraction osteogenesis.