A comparative analysis of distal locked and unlocked long proximal femoral nail antirotation (PFNA-II) in the fixation of stable intertrochanteric fractures

Abstract

Purpose

Long proximal femoral nail anti-rotation (PFNA-II) is a preferred implant in recent years for fixation of pertrochanteric fractures, especially in osteoporotic patients. The purpose of this study is to prospectively investigate the effect of distal locking in long PFNA-II fixation of stable intertrochanteric fractures.

Methods

A total of 58 patients with isolated stable intertrochanteric fractures and treated in our hospital during the study period of 2017–2019 by distal locked or unlocked long PFNA-II fixation were included in this study. Patients who had multiple injuries or open fractures were excluded. There were 40 female and 18 male patients, with 33 affecting the left side and 25 the right side. Of them, 31 belonged to the distal locked group (group A) and 27 to the unlocked group (group B). Surgical procedures and implants used in both groups were similar except for the distal locking of the nails. General data (age, gender, fracture side, etc.) showed no significant difference between two groups (all p > 0.05). The intraoperative parameters like operative time, radiation exposure and follow-up parameters like functional and radiological outcomes were recorded and compared. Statistical tests like the independent samples t-test Fischer's exact and Chi-square test were used to analyze association.

Results

The distribution of the fractures according to AO/OTA classification and 31A1.2 type of intertrochanteric fractures were most common in our study. All the included fractures united and the average functional outcome in both groups were good and comparable at the end of one year. The operative time (mL, 107.1 ± 12.6 vs. 77.0 ± 12.0, p < 0.001) and radiation exposure (s, 78.6 ± 11.0 vs. 40.3 ± 9.3, p < 0.001) were significantly less among the patients in group B. Fracture consolidation, three months after the operative procedures, was seen in a significantly greater proportion of patients in group B (92.6% vs. 67.7%, p = 0.025). Hardware irritation because of distal locking bolt was exclusively seen in group A, however this was not statistically significant (p = 0.241).

Conclusion

We conclude that, in fixation of stable intertrochanteric fractures by long PFNA-II nail, distal locking not only increases the operative time and radiation exposure but also delays the fracture consolidation and increases the chances of hardware irritation, and hence is not required.

Introduction

One of the most common fractures encountered around the hip joint are the intertrochanteric fractures.¹ As per the epidemiological data, a total of 1.6 million patients suffered from osteoporotic hip fractures worldwide every year and this number is expected to increase by six folds by 2050.² The increasing life span across the globe has significantly increased the incidence of pertrochanteric fractures in the last decade.³

With newer fixation technology and evolving implant design, there has been a significant shift towards the usage of intramedullary devices for intertrochanteric fracture fixation.4, 5, 6, 7 Dynamic sliding lag screw with a fixed angled construct was the most preferred fixation technique for a stable intertrochanteric fracture prior to the advent of intramedullary fixation techniques for intertrochanteric fractures.⁵

With inherent advantages like better biomechanical construct of the fixation, lateral wall buttress effect, resisting axial bending forces and also its load sharing natures makes these intramedullary devices most suitable for osteoporotic fractures of the hip.⁸ The earliest intramedullary nail to manage intertrochanteric fractures were introduced by Halder -- the cephalomedullary nail introduced in the year 1980. It was a short nail with thicker profile screw into the femoral neck and head.⁹ This fixation technique is less invasive, reduces the surgical time, decreases blood loss and is superior with respect to biomechanics and stability.^10,11 There are lots of modification and improvements in the design of these nails with various companies coming up with their own versions of implant design.¹²

Currently, both short and long cephalomedullary nails are being widely used all over the world. The former needs less operative time and has no issues in cases with excess of femoral bowing, however they are associated with a higher complication rate like anterior thigh pain, stress fracture of the femoral shaft at the level of distal end of the nail and as a result of this they have more revision rates than the long nails.13, 14, 15, 16, 17, 18

There is a constant debate whether one should do a distal locking in every long cephalomedullary nailing procedure for an intertrochanteric fracture. In unstable intertrochanteric fractures, it is mandatory to apply the distal locking to prevent subsequent varus collapse or rotational instability,19, 20, 21, 22, 23, 24 however, in stable intertrochanteric fracture patterns, distal locking may not be necessary.

As per the biomechanical studies by Rosenblum et al.,²⁵ there was no great change in the stress load on femur as well as the tension on the proximal femur when distal locking is not performed for a stable intertrochanteric fracture. Distal locking is not free of complications. The fascia lata irritation is one of the commonest issues apart from increased bleeding, synovial irritation, stress fractures and rarely iatrogenic vessel injury apart from increasing the operative time and radiation exposure.25, 26, 27, 28

Among the various designs of cephalomedullary nails, proximal femoral nail anti-rotation (PFNA-II, Depuy Synthes, Switzerland) is preferred in recent years for fixation of pertrochanteric fractures, especially in osteoporotic patients. The purpose of this study is to compare the effect of distal locking in long PFNA-II fixation in the management of stable intertrochanteric fractures. To the best of our knowledge, a study with these specifications has not been done so far.

Methods

General data and grouping

This study was carried out in a tertiary referral hospital in Mangalore, Karnataka, India (ethical approval No.: IECKMCMLR-09/202/254). This was a prospective study comparing the functional and radiological results of stable intertrochanteric fractures treated surgically by either distal locked or unlocked long cephalomedullary nails with helical blade (PFNA-II nail). Patients with isolated stable intertrochanteric fractures in the study period of 36 months (2017-2019) who have been treated in our hospital with this implant were included. Patients who had multiple injuries or open fractures were excluded. Two teams of orthopaedic surgeons, one preferred distal locked long PFNA-II nail (group A) and the other used long PFNA-II nail without distal locking (group B) to manage stable intertrochanteric fractures. Surgical procedure and implants used in both groups were similar.

During the study period, a total of 58 patients of intertrochanteric fractures were enrolled, including 31 consecutive patients in group A and 27 in group B. There were 40 female and 18 male; 33 left and 25 right (Table 1). According to AO/OTA classification, there were 37 cases (63.8%) of type 31A1.2, 14 cases (24.1%) of 31A1.3, two cases (3.4%) of 31A3.1 and five cases (8.6%) of 31A3.2.31. Patient variables like age, gender, fracture side, and fracture types according to AO/OTA classification showed no significant differences. Informed consent was taken from all the patients included in the study.

Table 1.

Demographics details of patients with stable intertrochanteric fractures included in the study.

Group	Mean age (year)	Male/Female	Fracture side (right/left)
A (Lock, n = 31)	66.2 ± 13.3	12/19	14/17
B (unlocked, n = 27)	65.7 ± 10.0	6/21	11/16
t/X2 value	0.145	1.833	0.115
p value	0.885	0.176	0.735

Surgical procedure

All patients received operation under spinal anaesthesia. C-arm image intensifier was used for checking the adequacy of reduction and fixation with long PFNA-II. After positioning the patient on the traction table, fracture was reduced and skin preparation was done. Provisional fixation of the intertrochanteric fracture was done with a Steinman pin passed from lateral cortex to the neck and head of the femur, placed closer to the anterior cortex. Then appropriate sized, side specific PFNA-II was inserted using the tip of the greater trochanter as the entry point. Fixation and compression across the fracture site was carried out with the appropriate sized helical blade. Thereafter patients in group A received distal locking of the nail by free hand technique, while patients in group B did not. Surgical wounds were closed in layers.

Intraoperative data like duration of surgery and fluoroscopy times in Severt's were collected. Patients in both groups received similar postoperative rehabilitation. Weight bearing as tolerated was started in the immediate postoperative period with the help of a walker stand, mainly strengthening of quadriceps and gait training. Patients were progressively weaned off walking aids as the fracture healing progressed.

During the follow-up, radiological and functional outcomes at six weeks, three months, six months and one year following the surgery were collected. Radiological parameters like time to union, any loss of reduction and implant failure were noted. Functional assessment at the end of one year of follow-up using Harris hip score was recorded. Any complications encountered during the follow-up and need for any subsequent surgical procedures were noted.

Data analysis

Data were analyzed using SPSS Statistics for Windows, Version 25.0; IBM Corp, Armonk, NY, USA. Statistical tests like the independent samples t-test, Chi-square test, and Fisher's exact test were used to test association. p < 0.05 was set as cut off to state statistical significant association.

Results

Operative time and radiation exposure

In group A, the mean operative time was (107.1 ± 12.6) min, range 91–143 min and mean radiation exposure was (78.6 ± 11.0) s, range 49–64 s. In group B, the operative time was (77.0 ± 12.0) min, range 70–95 min and radiation exposure (40.3 ± 9.3) s, range 40–54 s, both revealing significant difference (p < 0.001) (Table 2).

Table 2.

Comparison between operative time, radiation exposure and Harris hip score between the two groups of patients with stable intertrochanteric fractures (mean ± SD).

Group	Operative time (min)	Radiation exposure (s)	Harris hip score
A (Lock, n = 31)	107.1 ± 12.6	78.6 ± 11.0	85.7 ± 5.2
B (Unlocked, n = 27)	77.0 ± 12.0	40.3 ± 9.3	84.5 ± 5.5
t value	9.312	14.192	0.897
p value	< 0.001	< 0.001	0.374

Functional outcome

The mean Harris hip score at the end of one year follow-up in group A was 85.7 ± 5.2 (range 74–94) whereas in group B it was 84.5 ± 5.5 (range 71–93). There was no statistical significance between the two groups (p = 0.374). Thus the functional outcomes in both groups were good and comparable (Table 2).

Radiological outcomes

Fracture consolidation at three months after the operative procedure was seen in a much greater proportion of patients in group B with no distal locking, compared with group A with distal locking (92.6% vs. 67.7%, p = 0.025). However, union of the fracture consolidation was complete in all the patients of any groups at six months after surgery (Table 3). Two typical cases in each group are present in Fig. 1, Fig. 2.

Table 3.

Comparison of time to union between the two groups of patients with stable intertrochanteric fractures, n (%).

Group	Union at 3 months		Union at 6 months
	Yes	No	Yes	No
A (Lock, n = 31)	21 (67.7)	10 (32.3)	31 (100)	0 (0)
B (Unlocked, n = 27)	25 (92.6)	2 (7.4)	27 (100)	0 (0)
p value	0.025		1.000

Fig. 1.

Antero-posterior and lateral view radiographs of a 64-year-old male with intertrochanter fracture in Group A. (A) Preoperative films showing a stable intertrochanteric fracture; (B) Immediately after fixation with PFNA-II nail and distal locking and (C) At six months follow-up, union is achieved.

Fig. 2.

Antero-posterior and lateral view radiographs of a 73-year-old female with stable intertrochanter fracture in Group B. (A) Preoperative films showing a stable intertrochanteric fracture; (B) Immediately after fixation with PFNA-II nail and no distal locking and (C) At six months follow-up, union is achieved.

Correlation of complications between two groups

The most common type of complications observed among the 58 operated patients was deep vein thrombosis (n = 4 with 3 in group B by distal locking). All of them were medically managed. Two patients in group A and one patient in group B had superficial surgical site infection. They were treated by wound dressings and appropriate antibiotics. Hardware irritation was seen exclusively in group A (distal locking), though not statistically significant (p = 0.240). There were no cases with implant failure, helical blade cut through or back out. Two patients (both from group A) had constant knee pain associated with recurrent effusions which was attributed to the long or backed out distal bolt (Figs. 3A and B) and (Table 4). These were managed by removal of distal locking bolts after the fracture union.

Fig. 3.

Two cases in group A with distal locking developed constant knee pain. (A) Three month follow-up radiograph showing the back out of distal bolt (yellow pointer) resulting in knee synovitis and cause for constant pain. (B) Six weeks follow-up radiograph showing the distal bolt perforating the anterior cortex, resulting in constant hardware irritation (red pointer).

Table 4.

Association between locking or unlocking procedure with specific types of complications in patients with stable intertrochanteric fractures, n (%)

Group	Complications
	Deep vein thrombosis	Surgical site infection	Hardware irritation	Knee pain with recurrent effusion
A (Lock, n = 31)	1 (3.2)	2 (6.4)	3 (9.7)	2 (6.4)
B (Unlocked, n = 27)	3 (11.1)	1 (3.7)	0 (0)	0 (0)
Total	4 (6.9)	3 (5.2)	3 (5.2)	2 (3.4)
p value	0.442	1.000	0.241	0.494

Note: None of patients developed loss of reduction, peri-implant fracture or implant breakage.

Discussion

The osteoporotic intertrochanteric fracture is a major cause of mortality and morbidity in the elderly population worldwide causing increased health expenditure and disability adjusted life years. With the increasing life expectancy rates in India from 67 to 72 years, the number of geriatric hip fractures would increase in the coming years, adding a huge burden to our health and economic system.²⁹ Roughly, about 0.3 million hip fractures are encountered in India every year. The mortality at the end of three years after hip fractures is about 26%.³⁰

Using locked or un-locked cephalomedullary nails for stable intertrochanteric fractures have been always debatable. Distal locking makes the construct very stiff, rigid and has its own complications. Apart from increasing the incidence of complications specific to distal locking, it has been postulated to increase the operative time, blood loss and radiation exposure to the healthcare professionals in many studies.^22,24,31, 32, 33 This led us to prospectively compare the intraoperative and follow-up variables between two groups of patients with stable intertrochanteric fractures treated by long PFNA-II, where in one group (A) received distal locking and the other (B) did not.

In our study, the group B had a significantly shorter (p < 0.01) operative time compared to group A. This difference is attributed mainly to the time saved by not locking the nails distally. As per Boraiah et al.,³⁴ the average time needed to do the procedure is increased by about 12 min when distal locking is performed with free hand technique. This not only adds to the extra operative time but also adds the cost to the patient, apart from possible complications like knee synovitis and tensor fascia lata irritation due to the distal bolts, fractures distal to the tip of the nail due to stress risers and iatrogenic neurovascular complications which happens when drilling the cortices, the superficial femoral vessels can get injured when the drill is accidently drilled further inside for inserting bolts.^{22,26,31,35,36}

Radiation exposure among the health care workers is one of the major concern currently. Distal locking bolts need to be put under the guidance of fluoroscopy with free hand techniques, which invariably puts the surgeons and other health care workers at risk. As per our study, there was significant difference (p < 0.005) regarding the radiation exposure between two groups. Thus additional radiation exposure can be avoided in stable intertrochanteric fractures by not doing distal locking of long cephalomedullary nails (PFNA).^24,31,32

All the fractures included in this study had union at the end of one year, however, 10 cases from group A (three cases of type 31A1.2 and seven cases of type 31A1.3) and two cases from group B (one case of type 31A3.2 and one case of 31A1.3) showed the lack of complete consolidation at three months. At six months, all of them achieved complete consolidation. With the usage of the distal bolts, the construct becomes biomechanically stiffer, leading to a delayed healing at the fracture site.^24,31

The functional outcomes in both groups at the end of one year were good and comparable, thereby indicating no additional advantage gained by distal locking. Hardware irritation and constant knee pain with recurrent effusion were exclusively seen in group A (distal locking), though this was not statistically significant, neither do other complications.

Distal locking has been recommended in cases of intertrochanteric fractures in presence of severe osteoporosis, unstable pattern and severe comminution.19, 20, 21, 22, 23, 24^,31,36 However, based on the results of our study, we conclude that, in fixation of stable intertrochanteric fractures by long PFNA-II, distal locking not only increases the operative time and radiation exposure but also delays the fracture consolidation and increases the chances of hardware irritation, and hence is not required.^31,35,36

As per our literature review, this is one of a kind study comparing the outcomes between distal locked vs. unlocked long PFNA-II for stable intertrochanteric fractures in Indian population. A randomized prospective multicentric study with a larger sample size would be needed to substantiate these findings. Besides this study has limitations like small sample size, short follow-up period, and this study has not looked into the comorbidities of patients.

Funding

Nil.

Ethical statement

This study has been approved by the local ethical committee (IECKMCMLR-09/202/254).

Declaration of competing interest

The authors have no conflicts of interest to declare that are relevant to the content of this article.

Author contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Atmananda Hegde, Vikrant Khanna, Chethan Shetty and Prajwal Mane. The first draft of the manuscript was written by Atmananda Hegde and all authors commented on previous versions of the manuscript. Statsitics was by Nitin Joseph. All authors read and approved the final manuscript.