Purpose: The Less Invasive Stabilisation System (LISS) for fixation of the proximal femur is an automatic preformed fixator with three sizes. The self-perforating self-threading screws are locked into the plate fixator providing angular stability. Unlike conventional implants, the LISS plate is not applied directly to the bone, avoiding friction forces and periosteal damage. Precise adaptation of the implant to the form of the bone is not necessary. The system can also be easily and rapidly used as a “gliding” plate. After reduction via a proximal incision, the plate-fixator is inserted between the anterior tibial muscle and the periosteum and fixed with monocortical screws inserted percutaneously.
Material and methods: Between January 1999 and August 2000, we treated 18 multiple trauma patients with fractures of the proximal femur in 17 patients (nine men and eight women) using the LISS in a prospective multicentric study. Mean age was 50 years (20–89), median, 43 years). The AO classification of the fractures was four type A, four type B, and 13 type C. There were 14 open fractures. We used the LISS in one patient to stabilise a valgus osteotomy. One patient had a 41-C2.3 (Schatzker type VI) fracture with a compartment syndrome. Bone allographs were used in two cases. Clinical and radiographic follow-up data was collected at 6, 12, 24 and 48 weeks.
Results: Two foreign subjects with 41-A3 and 41-B1 fractures were lost to follow-up. For the other patients, bone healing was achieved between six and twelve weeks. Mean follow-up was ten months (three to twenty months). We had one complication, the compartment syndrome mentioned above, which healed without sequelae after fasciotomy and secondary thin skin graft. Joint motion was symmetrical and pain free in all patients three months after surgery. There were no nerve or vessel lesions secondary to epiperiosteal displacement of the fixator, and no case of infection or loosening. We did however observe secondary loss of reduction with development of minimal varus in three patients with complex fractures.
Conclusions: These preliminary results with the LISS demonstrate its usefulness as an alternative to conventional fixation systems. It is undoubtedly a most useful method for intra-articular and metaphyseal fractures with diaphyseal fracture lines and for fractures with two levels. Complications appear to depend on the type of fracture and the quality of the reduction, as with other types of fixators.
