[Experimental studies of the biomechanical properties of hollow nails and solid nails for interlocking intramedullary nailing in the dog]

Functional outcome of patients of tibial fracture treated with solid nail (SIGN nail) versus conventional hollow nail - A randomized trial

BACKGROUND

Trauma related disabilities disproportionately affects low and middle income countries due to lack of resources, skills and optimal implants. Despite adequate animal studies, biomechanical studies, cohort studies and comparison studies we are not aware of any randomized trial to compare the functional outcome of SIGN (Surgical Implant Generation Network, US) solid nailing with a hollow nailing for tibial shaft fracture.

METHODS

Sixty patients (≥16 years) of closed and Gustilo grade I traumatic fractures of the leg were randomized into SIGN solid nailing or hollow nailing group. Cases with compromised soft tissue and grossly deformed medullary canal were excluded. Functional outcome and need for resurgery were the primary outcomes while the secondary outcomes were duration of surgery, intraoperative blood loss, overall pain (VAS), radiological union (RUST), surgery related complications (infection, malalignment, shortening, nonunion) and pain/range of motion (ROM) of knee/ankle. All SIGN surgery related data were entered and retrieved online from www.signsurgery.org.

RESULT

The demographical parameters were symmetrically distributed between the groups (p > 0.05). 2 cases in SIGN nailing and 4 cases in hollow nailing needed open reduction. The functional outcome, as assessed by blinded physiotherapist using Johner and Wruh criteria, was excellent in 18 (62.06%), good in 6 (20.68%), fair in 3 (10.34%) and poor in 2 (6.89%) for SIGN nail whereas it was 16 (57.14%), 8 (28.57%), 3 (10.71%) and 1 (3.57%) respectively for hollow nail. There was 1 case of implant failure and 1 case of infection. Intraoperative blood loss (397 ± 94.47 ml versus 350 ± 75.43 ml, p = 0.037) and duration of surgery (94.8 ± 14.57 min versus 82.0 ± 12.36 min, p = 0.001) were significantly more in hollow nailing group. At final follow up, overall pain on weight bearing (VAS score) and radiological union (RUST score) were 2.1 and 11.7 for SIGN nailing while they were 2.7 and 11.3 respectively for hollow nailing.(p = 0.41 and 0.45 respectively) The malrotation (p = 1.000), shortening (p = 1.000), varus-valgus angulation (p = 0.511), AP angulation (p = 0.706), ROM ankle (p = 0.239) and ROM knee (p = 0.086) were similar.

CONCLUSION

Solid SIGN nailing gives comparable functional outcome as conventional hollow nailing for tibia shaft fracture. For developing world with limited resources, SIGN nail is useful which is supplied freely and is designed to be used without image intensifier and fracture table.

A biomechanical comparison of the Surgical Implant Generation Network (SIGN) tibial nail with the standard hollow nail

OBJECTIVE

In developing countries, tibial shaft fractures are frequently stabilised using Surgical Implant Generation Network (SIGN) nails. Despite widespread use throughout the world, little is known regarding their biomechanical properties. This study aimed to compare the mechanical stiffness of the SIGN tibial nail with a standard hollow tibial nail.

METHODS

A fracture gap model was created to simulate a comminuted mid-shaft tibia fracture (AO/OTA42-C3) using synthetic composite bones. The constructs were stabilised with either a 9 mm solid SIGN nail or a 10 mm hollow Russell-Taylor nail. Both nail systems were interlocked proximally and distally. Following fixation, the specimens were loaded in axial, torsional, and cyclical axial modes to calculate construct stiffness and irreversible (plastic) deformation.

RESULTS

The mean axial stiffness for the SIGN nail constructs was 47% higher than mean stiffness for the RT nail constructs (p<0.001). The difference in torsional stiffness was not statistically significant. However, the SIGN group demonstrated 159% more irreversible deformation than the Russell-Taylor group (p=0.006) for the loading parameters studied.

CONCLUSION

The SIGN tibial nail, despite its slightly smaller diameter, can provide similar construct stiffness and stability, when compared to a larger hollow nail for stabilisation of tibial shaft fractures.