Clinical observation and finite element analysis of femoral stable interlocking intramedullary nail in intertrochanteric fractures.

PURPOSE: This study was designed to compare clinical outcomes of the femoral stable interlocking intramedullary nail (FSIIN) with proximal femoral nail anti-rotation (PFNA) for the treatment of intertrochanteric fractures (OTA 31A1 + A2).

METHODS

This study retrospectively analyzed a registered sample of 74 intertrochanteric fractures (OTA 31A1 + A2) surgically treated using FSIIN (n = 36) or PFNA (n = 38) from January 2015 to December 2021. The intra-operative variables (operation time, fluoroscopy time, intra-operative blood loss, length of incision) and fracture healing time were compared between the two groups in this study. Harris hip score (HHS) and visual analog scale (VAS) were used to evaluate the functional states. At the last follow-up, the incidence of related complications in patients was calculated. Eventually, the 3D finite element model was established to analyze the stress of FSIIN and PFNA.

RESULTS

The distribution of all basic characteristics was similar between the two groups (p > 0.05). The operation time, fluoroscopy time, intra-operative blood loss, and length of incision were significantly decreased in the FSIIN group (p < 0.001). The FSIIN group had a shorter fracture healing time than the PFNA group (p < 0.001). There is no significant difference between the two groups in the Harris and VAS (p > 0.05). The incidences of post-operative anaemia, electrolyte imbalance, varus malalignment, and thigh pain were significantly lower in FSIIN than in PFNA groups (all p < 0.05). The finite element results show that the stress shielding effect of FSIIN is smaller.

CONCLUSIONS

Our study revealed that FSIIN seemed to be superior to PFNA in the treatment of intertrochanteric fractures (OTA 31A1 + A2) due to less surgical damage and shorter fracture healing time.