Early results of reverse less invasive stabilization system plating in treating elderly intertrochanteric fractures： a prospective study compared to proximal femoral nail

Background Intertrochanteric femur fracture is common in elderly population. Though multiple treatment options are available, the choice of implant remains controversial. The reverse less invasive stabilization system （LISS） plating was introduced for treatment of a patient with ipsilateral intertrochanteric and midshaft femoral fractures. The aim of this research was to compare such technique to intramedullary nailing （proximal femoral nail, PFN） for intertrochanteric fractures.Methods Fifty-six patients with an age of at least sixty-five years and an AO/OTA type-A1 or A2 fractures were included and divided into LISS and PFN treatment group. Background parameters, fracture and surgery details were documented. Follow-up time was at least 12 months. Radiology, complication, Harris Hip Score and Rapid Disability Rating Score （RDRS） were recorded to evaluate fixation status and hip function for each patient during follow-up.Results There was no significant difference between the two groups in surgical time （（48.0±8.6） minutes, vs.（51.8±10.8） minutes, P=0.3836） and intraoperative blood loss （（149.1±45.1） ml vs. （176.4±25.4） ml, P=0.0712）. The LISS group had less postoperative haemoglobin （Hb） reduction （（10.2±4.5） g/L Hb, vs. （15.1-5.9） g/L Hb, P=0.0475）. There was no complication observed in PFN group. All 31A1 type fracture in LISS group showed 100% maintenance of reduction. One nonunion with locking screw breakage and 2 varus union were found in the LISS group. Postoperative hip function was similar between the two groups.Conclusions Though reverse LISS plating may not be recommended as a routine fixation method for elderly unstable intertrochanteric fractures compared to PFN, it may possibly be reserved for rapid fixation and damage control in polytrauma patients and ORIF of subtrochanteric and reverse oblique intertrochanteric fractures.

Comparative biomechanical study of reversed less invasive stabilization system and proximal femoral nail antirotation for unstable intertrochanteric fractures

Objective Unstable intertrochanteric fractures （ITFs） are mostly treated by proximal femoral nail antirotation （PFNA）,Inter-Tan,Asian Hip,and other new internal fixation devices.But for complex unstable fractures,such as crushed lateral wall of the greater trochanter,the loss of fixation point on lateral wall slightly reduces the fixing effect.This study aimed to compare the biomechanical strengths between reversed less invasive stabilization system （LISS） and PFNA for treatment of unstable ITFs.Methods Forty synthetic femurs were used to simulate unstable ITFs in vitro and were fixed using the reversed LISS or PFNA.These fractures were divided into two groups depending on whether the lateral wall of the greater trochanter is intact or not （AO classification：31-A2.3 and 31-A3.3,respectively）.The load-displacement of femur,stiffness,ultimate load,and cyclic fatigue resistance were detected using an incremental load test and a dynamic fatigue test through an MTS 858 test system.Results For both 31-A2.3 and 31-A3.3,the vertical sinking displacement （VSD） of the femoral head under 500 N load was insignificantly smaller after treatment with reversed LISS than with PFNA,and when the displacement was 5 mm,the femoral head bore insignificantly greater load.The fixation with reversed LISS resulted in greater axial stiffness of the femur but smaller ultimate load.During the same cycle in the dynamic fatigue test,the VSD was insignificantly smaller with the fixation of reversed LISS.Conclusion Reversed LISS and PFNA have similar biomechanical strength for unstable ITFs.This conclusion should be supported by additional large-size research on basic biomechanics and clinical application.This is the first comparative biomechanical study comparing reversed LISS and PFNA for unstable ITFs.