Introduction

The most common treatment options for fixation of osteoporotic distal femur fractures are retrograde nails and locking plates. There are proponents of more elastic titanium plates as well as more rigid steel plates; No clear superiority of one over the other has been established. We aimed to evaluate the mechanical differences between stainless steel and titanium locking plates in the fixation of distal femur fractures in osteoporotic bone. We hypothesized that due to its higher elasticity titanium locking plates can absorb more energy and are therefore less likely to “cut” into the bone compared to stainless steel locking plates resulting in improved metaphyseal osteoporotic fracture fixation.

Aims: Loss of distal þxation occurs with this the blade plate, especially in the setting of a very distal femur fracture and/or in osteoporotic bone. The LISS (Less Invasive Stabilization System) provides a þxation construct for supracondylar/intracondylar distal femoral fractures, with features including submuscular þxation and percutaneous placement of self-drilling unicortical þxed angled screws. The purpose of this study was to evaluate the biomechanical characteristics of the LISS versus the angled blade plate in an osteoporotic human cadaveric femoral model. Methods: Twenty-four matched pairs of fresh frozen human femora were utilized. Three groups of eight pairs each were tested to failure in one-time axial loading, one-time torsional loading and cyclical axial loading. A fracture model was created to simulate an AO 33–A3 fracture. Results: The average axial load to failure was 34% higher for the LISS compared with the blade plate (p = 0.03). All 8 LISS constructs failed by plastic deformation of the implant only, while 3/8 blade plates failed by loss of distal þxation. The blade plate had a 47% higher torsional moment to failure (p= 0.05). Permanent deformation after cyclical axial loading was signiþcantly lower for the LISS (p = 0.01). Conclusions: Of signiþcant interest is potential loss of þxation in catastrophic loading of a supracondylar femoral fracture þxation construct. In conclusion, biomechanical testing of the LISS demonstrates in comparison to the blade plate: (1) superior þxation of the distal femoral Ç block È in axial loading, (2) lower torsional strength, and (3) less permanent deformation in cyclical axial loading. The results further indicate that one-time axial loading of the LISS þxation construct will ultimately result in þxator plastic deformation, rather than screw pullout.

Aims: Published series of traditional plate þxation of the femur note rates of up to 69% primary bone grafting, 13% infection, 15% nonunion, 68% late complications, and 25% secondary surgical procedures. A shift from traditional plating to submuscular plating has thus ensued. This series entails an all-inclusive review of the plate þxation experience by two orthopaedic trauma surgeons in a þve-year period at a university trauma center. Methods: Between June 1996 and May 2001, 40 acute diaphyseal femoral fractures in 37 patients were managed utilizing dynamic compression plating via traditional Ç biological È plating with a formal lateral incision (n = 19), or submuscular plate þxation utilizing only a proximal and distal incision (n = 21). A comparison of reduction quality, union rates, and infection rates between traditional plate þxation and submuscular þxation was performed. Results: Thirty-nine of forty femoral shaft fractures healed without need of a secondary procedure. One nonunion occurred in the ORIF group. There was one infection in each group. Two patients treated by submuscular þxation developed signiþcant heterotopic ossiþcation around the femoral shaft which signiþcantly impaired knee motion. There were 6 cases of malreduction in the submuscular group, and none in the ORIF Group. Conclusions: Although the theoretical advantages of submuscular plating are well established, its utilization in the femoral shaft did not have a clear clinical advantage. In addition, its use appears to be more technically challenging, and is associated with a high rate of sub-optimal reductions.