It did not take long for surgeons around the world to realize that the Ilizarov apparatus (consisting of circular rings and tensioned transosseous wires) was not absolutely essential to the biology of distraction osteogenesis. New bone could form in a widening distraction gap in an appropriate biomechanical environment regardless of the method used to establish stability. The first change, therefore, was to substitute threaded half-pins for the tensioned transcutaneous wires, utilizing a standard Ilizarov apparatus [1, 2]. This measure reduced muscle impalement, particularly for the tibia and ulna, because these bones have subcutaneous surfaces ideally suited for half-pin transosseous fixation (Fig. 3.1).

Once surgeons became familiar with the Ilizarov apparatus, they sought ways to simplify the mounting configuration required for complex deformity correction. The hexapod concept, borrowed from flight simulators and other industrial applications, proved popular in this respect because it allowed repositioning of bone fragments in a three-dimensional space by adjusting the lengths of six struts. (With the classic Ilizarov assembly, surgeons had to create separate mechanisms to correct angulation, translation, and rotation deformities.) By applying the hexapod frame, surgeons could correct all planes of deformity with a general frame configuration and computer-generated correction formulation, based on initial mounting and deformity parameters.

Charles Taylor, an orthopedic surgeon in Memphis, Tennessee, created a particularly popular and easy to use device, the Taylor Spatial Frame^® . This fixator combined the hexapod system with an attractive computer interface that, once mastered, greatly simplified limb lengthening and deformity correction [3, 4] (Fig. 3.2).

Some surgeons eliminated the circular fixator altogether and used monolateral external devices to secure the bone fragments. DeBastiani (Verona, Italy), for example, used his Orthofix^® fracture reduction and stabilization device for limb lengthening after learning about distraction osteogenesis from Italian colleagues who travelled to Siberia, USSR, to learn Ilizarov’s methods [5]. As with half-pin mounting strategies, new bone formed in the widening distraction gap. However, some surgeons recognized that the quality and speed of maturation of the regenerate did not quite match what was routinely created with a classic Ilizarov mounting (Fig. 3.3).