EXTERNAL FIXATION - OPERATIVE TECHNIQUE, PINLESS FIXATION, CHANGING PROCEDURES

External Fixation-Technique: The advantages of external over internal fixation are as follows: a) endosteal and periosteal blood supply is u ndisturbed, b) ''low-tech'' equipment may be used, c) secondary adjust ments are possible and d) easy implant removal. These benefits however are outweighed by the main disadvantages of long term external fixati on i.e. pin complications and delayed union of fractures. Better under standing of postoperative management and careful application of screws of improved design will lead to better results. Today's standard appl ications of external fixation for tibial fractures is a unilateral fix ator, using Schanz screws. The pin-bone interface is the most critical site of all external fixation. By avoiding heat necrosis (low tempera ture drilling) and preventing micro motion at the pin-bone interface ( by applying bending - or more recently radial - preload), pin complica tions such as infection and loosening can be reduced. Two Schanz screw s are inserted into each main fragment and are connected with one shor t tube per fragment. The fracture is then reduced by using these tubes as handles. After reduction a third tube connects the first two by me ans of two tube-to-tube clamps. This type of fixation will easily allo w for three dimensional secondary corrections of alignment. Approximat ely three weeks following the injury some motion at the fracture site will stimulate callus formation. This can be achieved by destabilisati on, dynamisation or ''active stimulation'' of the fracture site [2]. P inless fixator: The pinless external fixator holds the fragements firm ly with pointed clamps that penetrate about one millimeter into cortic al bone without entering and contaminating the medullary canal. Theref ore this is an ideal primary stabiliser for fractures which will need secondary intramedullary nailing. The pinless fixator may also be empl oyed for skeletal traction or to interlock non-reamed intramedullary n ails. Secondary internal fixation: There are four principal approaches following initial external fixation (Fig. 1). Today most frequently i t will be a change from external fixation to reamed or unreamed intram edullary nailing, often with interlocking. The optimal time lag betwee n temporary external and definitive internal fixation seems to be with in six to ten days after injury. If Schanz screws are left in situ for more than three to four weeks, it is advisible to remove the screws f irst to permit healing at the pin sites before proceeding with interna l fixation.