Treatment with Locking Intramedullary Nailing for Intertrochanteric Fracture of the Femur Utilizing a New Awl with a Distal Positioner

Summary

Here, we present a protocol for accessing the guidewire of intramedullary femoral nailing in obese patients using an in-house designed awl. Using the new awl with a distal positioner for the guidewire insertion and opening the bone can increase efficiency in inserting the guidewire and reduce the difficulty of surgery.

Abstract

Interlocked intramedullary nailing is now established as the preferred method of managing femoral intertrochanteric fractures. Choosing the ideal entry point and inserting the guidewire accurately are key steps of the procedure. Several factors make the procedure more challenging, such as the supine position, obese patients, and the tip of the trochanter not aligning co-linear with the anatomic axis of the femoral medullary canal in the frontal plane. Our team has developed a new awl with a distal positioner that assists the guidewire insertion and entry portal of femurs. This comparative study analyzed 40 intertrochanteric fracture cases treated with locking intramedullary nailing, which were randomized to receive either the new awl incorporating a distal positioner (n = 20) or the conventional guide apparatus (n = 20). Operation time, blood loss, the success rate of the one-time insertion, radiation times, and bone healing time were recorded. The patients (21 males and 19 females) were treated with Gamma 3 and proximal femur nail antirotation (PFNA) with the help of the new awl with a distal positioner or conventional guide apparatus. There were no transoperative complications in the two groups. The surgical time in the new guide apparatus group was significantly shorter compared to the control group. The new awl group achieved a 100% success rate for one-time needle insertion, surpassing the control group's rate of 66.7%. The fluoroscopy time required for the new awl group was obviously shorter compared to that of the control group. However, no significant differences were observed in terms of intraoperative blood loss or bone healing time between the two groups. The newly designed guide awl with a distal positioner could reduce the difficulty in opening the femur for inserting the interlocked intramedullary nail. This tool is especially suitable for obese patients.

Introduction

Epidemiologic studies of hip fractures reported that the number of hip fractures has probably increased significantly in recent years¹. Intertrochanteric fracture of the femur as a common hip fracture represents about 31%-35% of all hip fractures². Interlocked intramedullary nailing is now established as the preferred method of managing femoral intertrochanteric fractures, offering superior biomechanical stability compared to extramedullary fixation systems. The proximal femoral nail anti-rotation (PFNA) from Depuy Synthes and Gamma 3 Nail System from Stryker are both commonly used for the treatment of intertrochanteric femur fracture³. However, when using these systems, especially in identifying nail entry points and inserting guidewire, there are always many problems. Before choosing an entry point, the first procedure is to make the hip adduction. However, the consequent issue is that the reduction cannot be maintained or lost. Because of the proximal valgus of the femurs, the orientation of a guidewire tends to be towards the medial femoral wall and will throughout. These problems are particularly acute in obese patients undergoing supine position.

Recent advancements in intramedullary nailing techniques have underscored the pivotal role of accurate entry-point localization for achieving optimal reduction and stability in intertrochanteric fractures. Conventional entry devices, such as standard awls or guidewire systems, frequently encounter challenges in maintaining alignment due to anatomical variations, proximal femoral valgus deformity, and soft tissue interference, especially in obese patients. Research highlights that improper guidewire placement significantly elevates the risk of medial cortical perforation, delayed union, and implant failure, with error rates surpassing 15% in cases involving osteoporotic bone or complex fracture patterns⁴. While current solutions, such as fluoroscopy-assisted navigation and adjustable targeting sleeves, partially mitigate these issues, they often necessitate prolonged radiation exposure or complex surgical procedures.

We designed a new awl with a distal positioner, which minimized guidewire malposition and preserved reduction stability during hip adduction. In the below protocol, the details of the new awl and the procedure are described. We used a proximal femoral intramedullary nail to treat the 40 patients with intertrochanteric femur fractures. In this study, 20 patients underwent the procedure with the help of the newly designed guider. As a comparison, the remaining patients underwent the surgery with the help of the regular guide apparatus.

Protocol

The clinical application of this new apparatus has been approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology. The newly designed guide apparatus is shown in Figure 1. The guide apparatus consists of several parts, including an excellent grip handle, a cannulated curved awl that can insert a 3 mm guidewire, a hammering point, and the distal positioner. The guidewire passing through the awl will deviate 15°-20° to the lateral of the trunk, increasing the operating space.

1. Preparation

1. Patient position: Position the patient supine on a radiolucent table. Position the contralateral limb in an adjustable leg holder. Abduct the torso 10°-15° to allow clear access to the intramedullary canal.
2. Image intensifier position: Position the image intensifier (G-arm) in the ipsilateral to obtain both anterior-posterior and lateral projections.

2. Operational procedure

1. Fracture reduction: Maintain traction and internal rotation of the ipsilateral leg under image intensifier control.
2. Drape the patient for the standard femoral nail procedure. Disinfect the surgical field with iodine povidone, extending longitudinally from the costal margin to the foot and transversely from the anterior midline beyond the posterior spine.
3. Position four sterile towels strategically.
   1. Cover the posterolateral hip with the first, the inguinal region with the second, and wrap the anterior and lateral thigh with the third and fourth, securing them with towel clips or adhesive drapes.
   2. Extend the sterile field with middle sheets, then center a large fenestrated drape over the hip while encapsulating the distal limb using a sterile stockinette and elastic bandage.
4. Make a longitudinal skin incision approximately 3-5 cm in length, placing it 2-3 cm proximal to the trochanteric apex and extending along the axis of the femoral shaft. Dissect the gluteus medius fascia. Palpate the tip of the greater trochanter.
5. Choose an ideal entry point at the tip of the greater trochanter. Under anteroposterior (AP) fluoroscopy, align the entry point with the trochanteric tip; under lateral fluoroscopy, confirm axial alignment with the medullary canal by centering the entry point within the trochanteric profile.
6. Place the awl's tip at the ideal entry point. Then make a small incision at the site of the distal position tube and insert a customized 3 mm wire through the tube. Confirm the tip of the K-wire positioning along the lateral of the femur.
7. Advance the customized wire to the correct depth to offset the valgus of the proximal femur. Under the A-P view and lateral view, confirm the extension of the tip of the awl and the continuation of the femoral medullary cavity.
8. Insert a 2.5 mm diameter guidewire through the tube of the awl into the femoral medullary cavity with a depth of approximately 15 cm. Check the position of the guidewire under the image intensifier.
9. Turn and push or tap gently with a hammer to open the proximal cortex, keeping the tip of the awl at the level of the lesser trochanter during the process.
10. Attach the intramedullary nail to the insertion handle using its threaded proximal locking mechanism. Align the nail's proximal end with the handle's coupling interface and secure the connection by tightening it with a torque-limiting wrench.
11. Insert the intramedullary nail while aligning its proximal end flush with the greater trochanter tip and terminating the distal end at the metaphyseal-diaphyseal junction of the femoral shaft, maintaining a 10-20 mm gap proximal to the femoral condyles.
12. Verify fracture reduction and the proximal locking position under the image intensifier. Assemble the aiming arm to the handle.
13. Insert the guidewire and verify nail depth and position for the helical blade or screw. After inserting the proximal blade or screw, complete the distal locking.

3. Post-operation

1. Define operative duration as the interval between the initial skin incision and the final dressing application. Record total fluoroscopy time in seconds using the G-arm machines.
2. Document the success rate of one-time insertion of the guidewire from the surgical records for analysis.
3. Obtain radiographs every 3-4 weeks until the bone healing is achieved and judge through the radiographic criteria of fracture healing⁵.

Results

Cohort demographics
Between June 2020 and February 2023, 40 patients (21 males and 19 females) with a mean age of 52 years (range 20-63) were admitted to Tongji Hospital with intertrochanteric femur fractures. The patients were treated with locking intramedullary nailing with the help of a newly designed guide apparatus or conventional guide apparatus. Based on the guide apparatus used during the operation, the patients were divided into two groups: the control group (n = 20) and the new guide appa...

Discussion

The intertrochanteric of the femur is an important pillar for weight bearing through the skeletal system. The area is prone to fractures due to high-level trauma in the young and trivial trauma in the elderly. The principle in the management of intertrochanteric fractures is a good reduction and strong internal fixation. The options contain extramedullary and intramedullary fixation^6,7. For stable intertrochanteric fractures, both fixation devices benefited the p...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Awl with a distal positioner	In house	N/A	The awl is to guide wire insertion and open the femoral bone.
Gamma3 system	Stryker	603611	The Gamma3 System is intended to achieve functionally stable osteosyntheses and stabilization of bones and bone fragments
Hip joint surgical instrument set	Shanghai Jinzhong Surgical Instruments Co., Ltd.	P24020	The hip joint surgical instrument set is to facilitate surgical procedures involving locked intramedullary nailing for the treatment of intertrochanteric femoral fractures.
Image intensifier (G-arm)	Swemac imaging	04-7100020A	The image intensifier (G-arm) is to obtain both anterior-posterior and lateral projections.
Iodine povidone	Wuhan Operation Fine Chemical Co.,Ltd	WYH001	Iodine povidone is to disinfect the surgical field.
PFNA	DePuy Synthes	04.045.870S	PFNA permits an intramedullary approach for the fixation of fractures of the femur.