Functional and Radiological Outcomes of Proximal Femoral Nail Antirotation 2 (PFNA2) Fixation for Intertrochanteric Femur Fractures in an Asian Population: A 3-Year Retrospective Analysis

Title:

Functional and Radiological Outcomes of Proximal Femoral Nail Antirotation 2 (PFNA2) Fixation for Intertrochanteric Femur Fractures in an Asian Population: A 3-year Retrospective Analysis.

Abstract

Background: Intertrochanteric femur fractures are a common orthopedic injury in the elderly population, often resulting from low-energy trauma. Achieving stable fixation that allows early mobilization remains a key goal of management. The Proximal Femoral Nail Antirotation 2 (PFNA2) system offers enhanced rotational stability and better anatomical compatibility for Asian individuals. This study aimed to evaluate the functional and radiological outcomes of PFNA2 fixation in patients with intertrochanteric femur fractures treated at MOSC Medical College, Kolenchery,Ernakulam, Kerala, India.

Materials and Methods: A retrospective study was conducted on 120 patients, aged 50–90 years, who underwent PFNA2 fixation for intertrochanteric femur fractures at MOSC Medical College, Kolenchery, Ernakulam, between January 2021 and December 2023. Fractures were classified according to the Boyd and Griffin classification. Functional outcomes were assessed using the Harris Hip Score (HHS), and radiological evaluation was done for fracture union, implant position, and complications. Patients were followed up for a minimum of 12 months. Results: The mean age of patients was 72.4 years, with a male-to-female ratio of 1:1.3. The average time to radiological union was 14.8 weeks. Based on the Harris Hip Score, 80% of patients achieved good to excellent outcomes, 15% had fair results, and 5% had poor outcomes. Complications observed included varus malalignment in 4%, superficial infection in 3%, and limb shortening in 2% of cases. No cases of implant failure or cut-out were reported. Conclusion: PFNA2 fixation provides reliable and excellent functional and radiological outcomes in the management of intertrochanteric femur fractures, especially in elderly patients. The implant design allows for stable fixation, early rehabilitation, and a low complication rate, making it a preferred choice for treating these fractures.

Keywords: PFNA2, Intertrochanteric femur fracture, Harris Hip Score, Functional outcome, Radiological outcome, Elderly patients.

Introduction

Intertrochanteric femur fractures are a significant public health burden, primarily affecting the elderly population due to osteoporosis and a predisposition to falls [1, 2]. With the global increase in life expectancy, the incidence of these fractures continues to rise, placing substantial demand on healthcare systems. The primary goals of treating these fractures are to achieve stable internal fixation, facilitate early mobilization, minimize complications, and restore pre-injury function [3].

Surgical management, typically involving internal fixation, is the gold standard for most intertrochanteric fractures. Intramedullary nailing, such as the Gamma Nail and the Proximal Femoral Nail (PFN), has gained popularity due to its biomechanical advantages, including a shorter lever arm and central load-bearing, which is particularly beneficial in osteoporotic bone [4].

The Proximal Femoral Nail Antirotation 2 (PFNA2) system is a second-generation cephalomedullary nail. Its design incorporates a large-diameter single helical blade, which is intended to compact cancellous bone, thus providing high primary stability and improved resistance to cut-out [5]. Furthermore, its specific design features, such as a narrow nail tip and an anatomical curvature, are often better suited for the smaller and straighter femur commonly observed in Asian populations [6].

This study aimed to retrospectively evaluate the functional and radiological outcomes of PFNA2 fixation in a cohort of elderly patients with intertrochanteric femur fractures treated at a tertiary care center in South India, focusing on union rates, functional recovery measured by the Harris Hip Score (HHS), and the incidence of complications.

Materials and Methods

Study Design and Population

This was a retrospective study. We reviewed the medical records of all patients who underwent surgical fixation with the PFNA2 system for intertrochanteric femur fractures at the Department of Orthopaedics, MOSC Medical College, Kolenchery, Ernakulam, Kerala, India, between January 2021 and December 2023.

Inclusion and Exclusion Criteria

Inclusion Criteria:

1. Age between 50 and 90 years.
2. Unilateral, closed intertrochanteric femur fractures (Type A1, A2, or A3 according to the AO/OTA classification, or Boyd and Griffin Types I-IV).
3. Treatment with the PFNA2 intramedullary nail system.
4. Minimum post-operative follow-up period of 12 months.

Exclusion Criteria:

1. Open fractures.
2. Pathological fractures (excluding senile osteoporosis).
3. Pre-existing ipsilateral hip joint diseases (e.g., severe arthritis, previous hip surgery).
4. Polytrauma patients with other unstable long bone fractures.
5. Patients lost to follow-up before 12 months.

A total of 120 patients meeting the inclusion criteria were included in the final analysis.

Surgical Technique

All surgeries were performed by experienced orthopedic surgeons under spinal or general anesthesia, typically on a fracture table in a supine position. The standard minimally invasive technique for PFNA2 insertion was employed.

Figure 1: Pre operative x rays

1. Reduction: Closed reduction was attempted under fluoroscopy guidance. Open reduction was performed only if closed reduction failed to achieve acceptable alignment.
2. Nail Insertion: A standard lateral incision was made, and the entry point was centered on the tip of the greater trochanter. The nail was inserted after sequential reaming of the medullary canal.
3. Helical Blade Insertion: The single helical blade was inserted into the femoral head, aiming for a Tip-Apex Distance (TAD) of less than 25 mm, a critical parameter for preventing cut-out [7].
4. Distal Locking: Static distal locking was performed using the jig or freehand technique.
5. Wound Closure: Standard layered closure was performed, and a negative suction drain was placed if deemed necessary.

Figure 2: Immediate post operative X ray (AP view)

Fracture Classification

Fractures were classified pre-operatively based on the Boyd and Griffin classification from plain radiographs (anteroposterior and lateral views) and corroborated by intraoperative fluoroscopy (Table 1).

Table 1: Distribution of Intertrochanteric Fractures by Boyd and Griffin Classification

Outcome Assessment

All patients were followed up at 6 weeks, 3 months, 6 months, and 12 months post-operatively.

Functional Outcome

Functional outcome was assessed at the 12-month follow-up using the Harris Hip Score (HHS) [8]. The HHS ranges from 0 to 100 points and was categorized as follows:

• Excellent: 90–100 points
• Good: 80–89 points
• Fair: 70–79 points
• Poor: <70 points

Radiological Outcome

Radiological union was defined as the presence of continuous bridging bone across the fracture site on both anteroposterior and lateral radiographs, with obliteration of the fracture line and absence of pain at the fracture site upon weight-bearing. The time to radiological union was recorded. Implant position, specifically the TAD, was measured on the immediate post-operative radiographs.

Complications

Intraoperative and post-operative complications were recorded, including deep vein thrombosis (DVT), infection (superficial or deep), varus malalignment (defined as a collapse of >5 degree or loss of neck-shaft angle), implant cut-out, implant failure, and non-union (absence of union by 9 months).

Statistical Analysis

Descriptive statistics, including mean and standard deviation (SD) for continuous variables and frequencies and percentages for categorical variables, were calculated. Data analysis was performed using SPSS statistical software (version 25.0).

Post-operative Rehabilitation

A standardized, protocol-based rehabilitation program was followed for all patients.

Immediate Post-operative Phase (Days 1–7)

• Weight-Bearing: Touch-down weight-bearing (TDWB) was initiated on the operated limb using a walker or crutches, depending on the stability of the fixation and patient tolerance. Non-weight bearing was reserved only for severe comminution or unstable fixations.
• Physiotherapy: Passive and active-assisted range of motion (ROM) exercises for the hip and knee were started on Day 1. Isometric quadriceps and gluteal muscle strengthening exercises were also initiated.
• Deep Breathing Exercises: Encouraged to prevent pulmonary complications.

Intermediate Phase (Weeks 2–6)

• Progression of Weight-Bearing: Patients progressed from toe touch weight bearing to partial weight-bearing (PWB) whwn pain reduced and muscle control improved. The goal was to attain about 25% of body weight.
• Strengthening: Progressive resistive exercises for hip abductors, extensors, and knee flexors/extensors.
• Gait Training: Focus on proper gait pattern with assistive devices like walkers.

Late Phase (Weeks 7–12)

• Radiological Assessment: Follow-up X-rays were taken at 6 weeks. If adequate callus formation and early union signs were present, PWB was increased to 50% of body weight.
• Full Weight-Bearing: Typically initiated between 8 and 12 weeks, contingent on clinical and radiological signs of union.
• Functional Training: Stair climbing, balance exercises, and endurance training.

Maintenance Phase (After 3 Months)

• The goal was to achieve maximum functional recovery.
• Patients were advised to continue home exercise programs and transition away from walking aids as tolerance allowed. Final functional outcome assessment (HHS) was performed at 12 months.

Flow Chart 1: Post-operative Rehabilitation Protocol

Results

Demographic and Clinical Characteristics

The study included 120 patients. The mean age was 72.4 +/- 8.6 years (range, 50–90 years). There was a female predominance, with a male-to-female ratio of 1:1.3 (52 males, 68 females). The average duration of surgery was 60 ± 15 minutes, and the mean estimated blood loss was 200 +/- 50 ml. The average Tip-Apex Distance (TAD) achieved was 18+/- 2 mm.

Radiological Outcomes

The average time to radiological union for the entire cohort was 14.8 +/-2.1 weeks (range, 12–24 weeks). Complete radiological union was achieved in 118 out of 120 patients (98.3%). Two patients were diagnosed with delayed union but eventually united after 6 months with focused physiotherapy and non-surgical management. No cases of non-union (absence of union at 9 months) were reported.

Figure 3 : 6 months post operative X ray

Figure 4 : 1 year post operative X ray

Functional Outcomes

The mean Harris Hip Score (HHS) at the 12-month follow-up was 86.5+/- 9.5 points. The functional results, categorized according to the HHS, were excellent in 40 patients (33.3%), good in 56 patients (46.7%), fair in 18 patients (15.0%), and poor in 6 patients (5.0%). Overall, 80% of patients achieved a good to excellent functional outcome.

Table 2: Functional Outcome Assessment using Harris Hip Score (HHS) at 12 Months

Figure 5 : Distribution of Functional Outcomes (Harris Hip Score) at 12 Months

Complications

The overall complication rate was low, with a total of 9 patients (7.5%) experiencing minor or local complications (Table 3).

Table 3: Summary of Complications

The most common complication was varus malalignment, observed in 4.2% of cases. All five cases were minor (collapse <10 degree) and did not necessitate revision surgery; they were managed conservatively. Superficial surgical site infection occurred in 3.3% of patients and resolved completely with a short course of oral antibiotics. Importantly, no cases of implant failure, helical blade cut-out, or deep infection requiring hardware removal were recorded, which is a key finding for the biomechanical stability of the PFNA2.

Discussion

The management of intertrochanteric femur fractures in the elderly is challenging. Our findings demonstrate that PFNA2 fixation provides excellent to good stability and reliable outcomes in this challenging patient population especially elderly patients.

The mean time to radiological union in our study was 14.8 weeks, which is consistent with the other general literatures on intramedullary fixation for these fractures, often cited between 12 and 20 weeks [9]. The high union rate (98.3%) and the absence of implant cut-out or mechanical failure are the biomechanical advantages of the PFNA2 system. The single, large-diameter helical blade is proved to provide superior rotational stability and better purchase in osteoporotic bone compared to screws of conventional PFN, thus reducing hardware migration and subsequent cut-out [5]. This excellent hardware performance is likely due to meticulous surgical technique, with an average Tip-Apex Distance of 18.5 mm, well below the critical threshold of 25 mm [7].

The functional outcome, as measured by the Harris Hip Score (HHS) [8], showed that 80% of our patients achieved good to excellent results. This is comparable to many published series using various intramedullary nails, where good-to-excellent results often range from 70% to 85% [10]. The emphasis on a structured, early mobilization rehabilitation protocol likely contributed significantly to this favourable functional recovery, as delayed weight-bearing can lead to prolonged hospitalization, muscle wasting, and loss of independence in the elderly [11].

The low complication rate (7.5% overall) further supports the efficacy of the PFNA2 system. The absence of deep infection or implant failure is a critical indicator of success.

A notable strength of this study is the focus on an Asian population. Anatomical studies suggest that Asian femur may be smaller, straighter, and have a more prominent anterior bow than their Caucasian counterparts, which can complicate the insertion of some Western-designed intramedullary nails [6].

Limitations

The main limitation of this study is its retrospective nature, which is susceptible to selection and information bias. The lack of a direct comparative group (e.g., against DHS or PFN) limits the ability to draw definitive conclusions about the PFNA2's superiority. Furthermore, relying on the HHS alone may not capture the full extent of patient-reported quality of life.

Conclusion

The Proximal Femoral Nail Antirotation 2 (PFNA2) system provides Good to excellent functional and radiological outcomes in the management of intertrochanteric femur fractures in the elderly population. Based on our 12-month follow-up data, the PFNA2 remains a preferred and effective choice for the surgical treatment of intertrochanteric femur fractures especially in osteoporotic bones.

Conflict of interest

The authors declare that they have no conflict of interest.

Funding

The research did not receive any funding.

Ethical approval

Ethical approval was not required.

Informed consent

Written informed consent was obtained from the patient.

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