The pinless external fixator--relevance of experimental results in clinical applications

The pinless external fixator was intended as a stable, temporary, minimally invasive fixator for severe tibial fractures ensuring safer conversion to an intramedullary nail. An in vitro study showed that the pinless fixator was mechanically not as stiff as the conventional AO tubular device, the main problem being low axial stiffness. This study involving initial clinical trials with the pinless fixator on tibial fractures in St. Gall is based on the experimental work and previous clinical experience of the main author. From June 1992 to June 1994 10 tibial fractures (eight II degrees and III degrees open, one closed with compartment syndrome, one infected non-union) were temporarily stabilized with a pinless fixator. In another patient a calcaneal traction device was applied. The pinless fixator was applied immediately in eight cases and three times as a secondary measure. All patients were scheduled for a secondary change of treatment. The tibiae were stabilized with four clamps and one anterior rod. The clamps were inserted via transverse stab incisions. Intraoperatively the pinless fixator was easy to handle and complications did not occur. Seven different surgeons needed an average of 20 minutes for insertion. Postoperative care was the same as for conventional fixators. Six patients were treated secondarily with an i.m. nail, three with an external fixator on average after 12 days. One patient died on day 1. The pinless fixator failed twice in one patient (incorrect insertion, fall). Reversible pain in the tendons of the foot extensor muscles was noticed. One superficial clamp track infection was seen. All clamps were reused more than three times. The pinless fixator is stable enough for temporary fracture fixation of the tibia in a four clamp one bar construction. A prerequisite for stability is the proper application technique ("grab test", rocking movements). Weight-bearing should be limited to a minimum and needs a compliant patient. The application technique is easy to learn suggesting that the pinless fixator could be an ideal tool for emergency stabilization. The primary application of this fixator leaves all further treatment modalities open (repeated debridements, evaluation of the open fracture). It may also be of particular value to many clinicians working with reamed nails as their only secondary treatment option for open tibial fractures.