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An outcome analysis of intertrochanteric fracture of femur managed with proximal femoral nail antirotation II

The types of implant used in these fractures have been divided into extramedullary implants and intramedullary nails. The choice of implant is mainly determined by the fracture pattern (stable or unstable). Unstable intertrochanteric fractures are those with major disruption of the posteromedial cortex because of comminution or are fractures with reverse oblique patterns or fractures with subtrochanteric extension. Fractures without posteromedial cortex disruption or subtrochanteric extension are considered stable.


INTRODUCTION
Intertrochanteric fractures commonly occur in elderly patients with osteoporosis and its incidence will continue to rise due to the increasing life expectancy. The main aim of surgery is to mobilize the patient early. It is crucial to use an implant that is minimally invasive, allows early weight bearing, and has low complication rates. 1,2 The types of implant used in these fractures have been divided into extramedullary implants and intramedullary nails. The choice of implant is mainly determined by the fracture pattern (stable or unstable). Unstable intertrochanteric fractures are those with major disruption of the posteromedial cortex because of comminution or are fractures with reverse oblique patterns or fractures with subtrochanteric extension. Fractures without posteromedial cortex disruption or subtrochanteric extension are considered stable. 3,4 Several clinical and biomechanical studies have analysed the results of different implants such as the dynamic hip screw (DHS), the Gamma nail (GN) and the proximal femoral nail (PFN). Those devices have suffered a variety of complications like cut-out, screw back out, implant breakage, femoral shaft fractures and subsequent loss of reduction. [5][6][7][8] PFN has some demerits like implant failure, screw cut out and screw migration which is also called z effect. In this Z effect proximal screw (de-rotation screw) of PFN migrate medially and distal screws (lag screw) migrate backward, while in reverse Z effect proximal screw (derotation screw) migrate laterally and distal (lag screw) migrate medially. Intramedullary nailing has advantage of short incision, less operative time, rapid rehabilition and thus decreased medical complications.
PFNA II is newer intramedullary implant developed to obtain better fixation strength in osteoporotic bones. Biomechanical studies has demonstrated that PFNA II blade has a significance of higher cut out resistance than other commonly used screw systems. 9

Source of data
This study was conducted in the Department of Orthopaedics, JLN Medical College & Hospital, Ajmer, during the period 1March 2017 to 31 October 2018 and were treated surgically using PFNA II for patients who were diagnosed with unstable intertrochanteric fracture femur.

Inclusion criteria
Inclusion criteria were closed unstable inter trochanteric fracture (AO TYPE31A2&31A3); ability to walk independently (walking aids are allowed) prior to injury.

Exclusion criteria
Exclusion criteria were open fracture; subtrochanteric fracture; intracapsular fracture neck of femur; pathological fracture; medically unfit patients.
The patients are taken up for surgery under spinal or epidural anaesthesia, positioned supine on fracture table, uninjured leg held in wide abduction. C-Arm image intensifier is positioned between patient`s leg. Close reduction of fracture by manipulation is performed. Minimum 30 cases were studied. Patients were followed up for a minimum period of 6 months. With each follow up clinical and radiological evaluation was done.

Statistical analysis
Statistical analysis was done using SPSS Software (IBM Version-20).

RESULTS
In the study, all the patients were above 60 years of age. The mean age of the patients was 70.83 years (>60 years) of age. Around 40% of the patients were female and around 60% of the patients were male. 90% of the patients had sustained low velocity injuries due to fall on floor or trivial trauma whereas around 10% sustained injuries due to RTA. In present study left side is more involved around (60%) than right side around (40%). All fractures were classified according to the A.O. classification. 19 patients have AO type AO31A2 and 11 patients have type AO31A3 fractures (Table 1).   Cut out of the implant 2 4.

AVN hip 0
The mean time in surgery was 38.2 minutes (30 -50 minutes). The mean amount of blood loss in surgery was 110.8 ml (50-160 ml). It is measured by soaked gauge pieces.21 patients have limb length shortening < 1cm, 9 patients have shortening more than 1 cm. Mean limb length shortening was 0.92 cm. 15 patients have radiological union time <14 weeks, mean radiological union time was 12.23 weeks. In general complications one patient had decubitus ulcer & one had deep vein thrombosis. In our study, we had screw pullout in 1 patient, 2 patient had cut out of the blade (Table 2 and 3).

Figure 1: Final outcome measures (assessed with Harris hip score).
The functional status according to Harris hip score was excellent in 30%, good in 40%, fair in 20% cases and poor in 10% cases. Mean Harris hip score is 82.86 (Figure 1).

DISCUSSION
Stable fixation for trochanteric fractures is the goal of treatment. It allows early weight bearing and restoration of function. The PFNA2 device is a reliable intramedullary implant that can share a large axial load, its helical blade achieves an excellent fit through bone compaction with less bone removal. The inserted blade prevents rotation by locking with the nail and accordingly, it may be a more suitable implant for unstable trochanteric fractures especially in the presence of osteoporosis. Biomechanical studies have shown that the blade has a higher resistance to head collapse than commonly used screw design.
Mean time for doing PFNA2 was 43.1 minutes. The mean amount of blood loss for was 109.1 ml. The mean union time for inter-trochanteric fractures 13.5 weeks. Zeng et al found that PFNA use was associated with a significant reduction in duration of surgery, overall complication rate, post-operative fixation failure rate, and intraoperative blood loss as compared to PFN. 10 Takigami et al also found that the surgical time and operative blood loss were lower with the use of PFNA as compared to PFN. 11 Takigami et al found cut out rates of 2%, Sahin et al found it to be 4.7% in their study. 12 Mora et al recommend PFNA2 for treatment of trochanteric fractures in the elderly as its blade demonstrated a lower incidence of cut out in their study. 13