In our cadaver study plating the fibula in addition to nailing the tibia decreased the mean rotation across the tibial osteotomy site compared to nailing the tibia alone. Although this is statistically significant (p=0.0034) it may not be clinically relevant as the mean values for ROM were 19.10 and 17.96 degrees respectively. Plating the fibula resulted in no statistically significant difference in the mean vertical displacement, angulation or neutral zone. Therefore, we may conclude that plating the fibula in a combined distal third tibia and fibula fracture does not enhance the stability of tibial IM nailing. The purpose of this study was to determine if combined distal third tibia and fibula fractures are more stable when fibular fixation is added to the standard tibial IM rodding. In combined distal third tibia and fibula fractures, plating the fibula does not enhance stability of intramedullary tibial nailing. No additional incision or soft tissue stripping is required for plating of the fractured fibula. The average range of motion in rotation was 19.1° for tibial and fibular fixation combined, and 18.0 ° for tibial fixation alone with a difference of 1.1°, which was clinically significant ( p=0.0034). The mean differences in vertical displacement, angulation, and neutral zone were not statistically significant. Five matched pairs of embalmed cadaveric lower limbs were dissected and stripped of soft tissue. Each tibia received a 9mm solid titanium nail that was locked proximally and distally. Fibular fixation consisted of a seven- hole LCDCP. A 1.5 cm section of tibia and a 1.0 cm section of fibula were removed. Testing was accomplished with an MTS machine. Vertical displacement was tested with an axial load to 500 N, rotation was tested with an internal and external torque of 5 Nm, and angulation was calculated from the vertical displacement data. All displacement data was measured across the osteotomy site. The mean range of motion in rotation was the only statistically significant finding. However, considering the average range of motion with and without fibular plating of 17.96° and 19.10° respectively, this finding is likely not clinically relevant.
“Delta fixation” was developed to treat low-grade L5 isthmic spondylolisthesis. It involves placement of pedicle screws into L5 and from S1 through the L5/S1 disc into L5 (Fig.1). A biomechanical comparison to standard Posterior Lumbar Interbody Fusion (PLIF) with two anterior cages and pedicle screws in L5 and S1 was made. Eight fresh frozen human specimens were instrumented with both fixations and tested. Delta fixation was significantly more stable in resisting rotation. It requires less manipulation of the nerve roots and spares the cost of the fusion cages. Our objective is to compare the stability of Delta versus PLIF fixation in the treatment of low grade isthmic spondylolisthesis Delta fixation provides superior initial stability, and therefore is an acceptable alternative to PLIF for the treatment of low grade isthmic spondylolisthesis of L5-S1. Symptomatic low-grade isthmic spondylolisthesis of L5 is often managed with PLIF. This procedure requires extensive manipulation of the cauda equine, posterior resection of the disc and the placement of two inter-body cages as spacers in addition to pedicle screws in L5 and S1. Delta Fixation has been developed to provide stable fixation with less nerve root manipulation and without the use of inter-body cages. It is therefore a safer alternative method of fixation that spares the additional cost of the fusion cages. When comparing Delta fixation to PLIF fixation the only statistically significant difference was found in axial rotation. Delta fixation had 2.05 degrees less ROM and 0.90 degrees less NZ compared to PLIF fixation with P values of 0.0052 and 0.0104 respectively. This demonstrates that the delta fixation is more stable than PLIF fixation. Eight fresh frozen human spines were used. Matched pairs were created and block randomization used to create two groups: PLIF fixation and Delta fixation groups. The specimens were instrumented with a grade II spondylolisthesis of L5-S1, tested, and then re-instrumented with the alternative fixation and tested again. Vertical displacement, axial rotation, flexion– extension and side bending were tested using an MTS machine. Please contact author for tables and/or diagrams.
