Impact of the Ilizarov apparatus on external fixation: Current modifications of the 75-year-old orthopedic tool

The Ilizarov apparatus was designed by its author 75 years ago and addresses a wide range of orthopedic conditions. Its classical assemblies are still self-sufficient and versatile. However, certain clinical scenarios require a more specialized approach, and some groups of patients may benefit from customized Ilizarov constructs. Engineering science has designed various external fixators for orthopedic purposes, and some of those have become the gold standard for specific clinical tasks. We aimed to determine the current state and novel modifications of specialized external fixators for specific clinical situations which are based on the principles of the Ilizarov method. They are half-pin-based fixators for temporal fracture fixation, ring or hybrid devices for gradual deformity correction, and compression-distraction devices tailored for definite limb segments. Gradual correction of deformities can be achieved with external hexapods incorporating universal reduction units. Alternatively, external fixators with special connection mechanisms are able to provide independent movement of the rings in six degrees of freedom. Deformity correction can be performed with combined or sequential use of external and internal fixators. Special devices were developed for moving the split fragment for revascularization of the tibia. The units of external frames on the foot were modified to consider its complex anatomy and the clinical needs ranging from correction of multi-plane deformities, joint arthrodesis to distraction arthroplasty. Mini-fixators are compact external fixators for small bones of the hand and foot. The varieties of external fixators based on the Ilizarov principles have been designed to fulfill an ultimate goal of improving treatment outcomes.