Avoiding malalignment in proximal femur fractures treated with newer generation cephalomedullary nails: Some technical tips

Accepted Manuscript Avoiding malalignment in proximal femur fractures treated with newer generation cephalomedullary nails: Some technical tips Arvind Kumar, Samarth Mittal, Aditya Jain, Vivek Trikha PII:

S0976-5662(18)30604-0

DOI:

https://doi.org/10.1016/j.jcot.2018.11.008

Reference:

JCOT 687

To appear in:

Journal of Clinical Orthopaedics and Trauma

Received Date: 5 October 2018 Revised Date:

3 November 2018

Accepted Date: 22 November 2018

Please cite this article as: Kumar A, Mittal S, Jain A, Trikha V, Avoiding malalignment in proximal femur fractures treated with newer generation cephalomedullary nails: Some technical tips, Journal of Clinical Orthopaedics and Trauma (2018), doi: https://doi.org/10.1016/j.jcot.2018.11.008. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Avoiding malalignment in proximal femur fractures treated with newer generation

Short Title: Avoiding malalignment in proximal femoral fractures

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Authors:

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cephalomedullary nails: Some Technical tips

1. Arvind Kumar

Department of Orthopaedics All India Institute of Medical Sciences New Delhi

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[email protected]

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Ex Senior Resident

2. Samarth Mittal

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Assistant Professor of Orthopaedics JPN Apex Trauma Centre

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All India Institute of Medical Sciences New Delhi, India

[email protected]

3. Aditya Jain Senior Resident Department of Orthopaedics

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All India Institute of Medical Sciences New Delhi

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[email protected]

4. Vivek Trikha Professor of Orthopaedics

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JPN Apex Trauma Centre All India Institute of Medical Sciences

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New Delhi, India [email protected]

Samarth Mittal

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Corresponding author:

Assistant Professor of Orthopaedics

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JPN Apex Trauma Centre

All India Institute of Medical Sciences

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New Delhi, India

[email protected]

Phone number: +91-9013562489

Conflict of interest: Nil Source of funding: Nil

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Avoiding malalignment in proximal femur fractures treated with newer generation

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cephalomedullary nails: Some Technical tips

Abstract

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Three techniques to avoid malalignment in proximal femoral fractures managed with

cephalomedullary nails, have been described. Issues related to rotational mismatch at fracture

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site, central placement of lag screw in femoral head neck fragment and limb rotation restoration have been addressed. We believe these simple techniques can help in minimizing malreduction in proximal femur fractures and result in favourable outcomes.

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Keywords: cephalomedullary nail; Fractures; hip; malalignment; proximal femur

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Introduction

Proximal femur fractures present as a major fracture load in orthopedic practice. Before the

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advent of cephalomedullary femoral nails, dynamic hip screw and dynamic condylar screw were the commonly used devices for treatment of such fractures, the latter being used for unstable ones [1,2]. With the trend gradually shifting towards less invasive techniques, newer

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cephalomedullary nails have become popular devices for treating these fractures [3,4]. While, in some nails fracture stabilization is achieved using a helical blade, impacted inside the bone

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without pre drilling, others involve the insertion of a sliding lag screw using the conventional drill and tap method. We have been routinely using both of these devices in our level I trauma centre. We have observed that unlike the nails involving helical blade which need direct impaction of blade into the bone, the nails using lag screw have a problem of rotation of

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proximal fragment, especially when the screw starts getting good hold in the cancellous bone. Adding an additional guidewire or two do not seem to be of much help against such strong rotational forces. Second issue which is common to both types of devices is that the proximal-

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lateral part of lag screw jig being opaque under fluoroscopy, prevents sufficient visualization of guidewire in in lateral view, especially the lateral half of the femoral neck and the trochanteric

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region, which is critical to direct it centrally in the femoral head and neck region. Also, once a guidewire enters the neck away from its centre in the lateral view, it can sometimes be very difficult to change its direction perfectly, without changing its position in the AP view. Third issue which is common to all intramedullary fixation devices, is of restoration of normal rotational alignment of lower limb in fractures with metaphyseal comminution. Previous studies have shown high incidence of rotational malalignment following intramedullary nailing in

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proximal femur fractures [7,8].We have successfully addressed these common problems with some previously undescribed but simple techniques and the same have been presented in this

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technical note.

Technique 1

Prevention of malrotation while inserting lag screw in proximal femur fractures ( figure 1

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Once the cephalomedullary screw guidewire has been inserted appropriately upto the

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subchondral bone of femoral head, reaming is done in regular fashion. After this, the cephalomedullary sliding screw is inserted using clockwise turns while paying attention to fluoroscopic imaging to note down any rotation at the fracture site. The moment rotation occurs at fracture site, the clockwise turning of screw is stopped and anticlockwise turning is done to

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restore the correct rotation. After correcting the rotational alignment of proximal fragment, as evidenced by matching cortices, interfragmentary compression is achieved using the compression device provided with the jig. Once a satisfactory amount of compression at fracture

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site is achieved, the fracture is stabilised against rotation with the spikes of fracture interdigitating amongst one another, and then the sliding screw is rotated clockwise to reach the

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appropriate depth of subchondral bone. We did not encounter any further rotation of proximal fragment on turning the sliding screw after this step in all the cases where such a situation was seen. The fracture ends probably lock with each other after achieving the compression and this prevents malrotation on further rotating the sliding screw. The same technique was also found to be useful when the cephalomedullary screw needed to be rotated back to align the screw handle, parallel or perpendicular to jig, as required in most cephalomedullary nails for positioning of the

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‘set screw’ or antirotation or inner screw over the cephalomedullary screw. The compression is applied using the compression device provided, before derotating the screw back. Once an appropriate amount of compression is achieved, the cephalomedullary screw can be safely

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derotated without affecting the fracture reduction. Figure 1 demonstrates the applicability of this technique.

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[insert figure 1]

Technique 2

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Central placement of cephalomedullary guidewire in lateral view with minimal fluoroscopy (figure 2)

While in the anteroposterior view both central and inferior placements of lag screw have been recommended, in lateral view the central position is preferred [5]. The radio-opaque part of

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cephalomedullary screw jig handle often blocks the view of starting zone of guidewire placement in lateral view. The guidewire is visualized, only after it has traversed significant distance from lateral cortex to the neck of femur. This zone is crucial in directing the guidewire as slight

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change in trajectory in this region can significantly change the endpoint of guidewire in femoral head. In this technique, we propose the use of cephalomedullary jig handle as a guide for the

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central placement of guidewire in lateral view. The jig handle was visualized in lateral view under image intensifier and its anterior and posterior edges were aligned parallel to or in line with the anterior and posterior edges of visualized part of neck. Once this alignment was achieved, we were able to successfully pass the guidewire centrally in lateral view without much use of image intensifier. The principle behind this is quite simple as the jig handle also provides attachment for cephalomedullary screw sleeve in its lower part, and both the jig handle and the

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cephalomedullary lag screw sleeve make contact with nail medially, which make them coplanar. In this way, the direction of jig handle in lateral view can be considered equivalent to that of

guidewire. Figure 2 demonstrates the application of this technique. [insert figure 2]

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Technique 3

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cephalomedullary screw sleeve and thus can be used to indirectly control the direction of

comminution (figure 3 and 4)

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Restoring appropriate limb rotation in proximal femoral fractures with metaphyseal

Previously various methods have been described for restoring normal femoral rotation after antegrade nailing. The commonly used method is to correlate femoral rotation to lesser trochanteric shape of uninjured side in neutral position [8]. However this does not solve the

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purpose when lesser trochanter is fractured or there is posteromedial comminution. Also, the cortical thickness method may not help when there is metaphyseal comminution [9]. Other fluoroscopic methods [17,18] describe the use of image intensifier as a guide, in which change in

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arc angle of image intensifier from the point of obtaining a perfect lateral view of distal femur first, to the point of obtaining perfect and parallel lateral view of femoral head and neck was

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measured and counted as rotational malalignment at fracture site which needed to be restored to normal femoral anteversion angle. Although these methods can be useful, the amount of excess surgical time and radiation they cost is unknown. Moreover, once the proximal fragment is fixed with a screw and the distal fragment is rotated to obtain an appropriate rotation, there is tendency of proximal fragment and Intramedullary nail to rotate as one unit due to frictional contact between the medullary canal bone of distal fragment and part of intramedullary nail within it.

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Consequently, the lateral view of femoral head neck region, which earlier acted as template for correcting distal fragment rotation, would not be valid anymore. To create balance between them will add to the surgical time and radiation. We describe a simple surgical technique which can

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significantly help in correcting malrotation in proximal femoral fractures with metaphyseal

comminution. Firstly, the cephalomedullary lag screw in inserted and the angle between lag screw axis and axis passing through centre of femoral neck and head region is measured (if the

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screw is not inserted centrally). The C arm is turned to obtained a true lateral view of distal

femur with both posterior condyles overlapping each other. A long 2mm or 2.5mm K wire or

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guidewire is inserted parallel to the C arm beam axis at a level near blumensaat line, in such a way that it should appear like a dot in lateral view (figure 3b). Another suitable guidewire or a long straight K wire is inserted in the cannulated cephalomedullary lag screw. Now an assistant takes a photograph of the two K wires intersecting each other closest to patients body, from the

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foot end. This angle between them needs to be corrected to normal femoral anteversion angle to restore appropriate rotational alignment when the cephalomedullary screw is inserted centrally in lateral view. Otherwise, the previously measured angle between the screw axis and femoral head

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neck axis, should be added or subtracted from anteversion angle if screw was placed anterior or posterior to neck head axis, respectively, to provide the angle needed to be maintained between

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the K wires/guidewires at the point of intersection closest to the limb (figure 4). When viewed from foot end, the proximal guidewire or K wire should always appear inferior to distal K wire, lateral to the point of intersection. The principle behind this technique is based on the radiographic and CT based femoral anteversion measurement methods which measure the angle between retrocondylar axis ( also known as posterior condylar axis) and the femoral head-neck axis [19,20] as shown in figure 3a.

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[insert figure 3] [insert figure 4]

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Discussion

Management of proximal femur fractures can be challenging sometimes, especially in fractures that are complex and have metaphyseal comminution. Even for the simple ones, the operative

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procedures are technically demanding and slight deviation from appropriate use of fixation

devices can lead to complications [11-15]. The newer generation cephalomedullary nails are

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commonly used fixation devices for such fractures. Previous studies have shown that cephalomedullary lag screw system takes significantly more surgical time than the helical blade systems [5,11]. Moreover, we have observed that the additional guidewires used with cephalomedullary lag screw, sometimes, fails to prevent rotation at fracture site in

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pertrochanteric fractures while tightening the lag screw, resulting in malreduction. Our first technique provides a simple solution to prevent such malreduction and can save surgical time. The recommended placement of cephalomedullary lag screw( or the blade in case of PFNA) is

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slight inferior or central in anteroposterior view and central in lateral view. Deviation from this could result in implant failure [11-16]. Our second Technique for central placement of

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cephalomedullary lag screw in lateral view is very simple and doesn't need any technical expertise. It can also save a lot of surgical time. Controlling overall rotation is difficult in cases with fractured lesser trochanter or with metaphyseal comminution as both lesser trochanter method and cortical thickness matching methods can’t be used (figure 5) [8,9]. Our third technique provides a direct measure of proximal fragment rotation and the same can be controlled without checking fluoroscopy shots multiple times. Other methods using fluoroscopy

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for aligning the proximal and distal fragments need fine adjustments as once the nail has been inserted inside medullary canal, it is difficult to rotate one fragment independent of the other. For more effective fluoroscopic control, one would need simultaneous lateral views of proximal and

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distal fragment which is not feasible in every setup. We have been routinely using these

techniques in our level I trauma centre without any technical difficulty. We believe these

technical tips can help in minimizing malreduction in proximal femur fractures and result in

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favourable outcomes. [insert figure 5]

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Funding

The authors received no financial support for the research, authorship, and/ or publication of this

Conflict of Interest:

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article.

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None of the authors have any conflicts to declare.

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Figure Legends Figure 1. Sequential fluoroscopic images of an unstable proximal femoral fracture during the insertion of cephalomedullary screw, showing a satisfactory reduction (a), which got disturbed

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while progressively rotating the screw (b). The reduction was restored by slightly de-rotating the screw backwards (c). After achieving compression in this reduced position, the screw was able to progress without disturbing the reduction (d).

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Figure 2. Sequential true lateral fluoroscopic images of femoral head and neck region (left to right) with cephalomedullary screw jig handle ( seen as radio-opaque shadow) kept parallelly

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aligned to the borders of femoral neck. Keeping the jig handle in this position helps in central placement of guidewire and cephalomedullary screw in lateral view. Figure 3. a) The femoral neck anteversion angle refers to the angle of the central head neck line (FNA) in the axial plane with reference to the retrocondylar or posterior-condylar condylar axis

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(PCA). Any guidewire (GW) placed parallel to retrocondylar axis (PCA) will provide the same angle with FNA as provided by PCA with FNA (A1 = A2), b) Image intensifier screenshot showing a true lateral view of distal femur with guidewire (GW) placed parallel to the

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retrocondylar axis by keeping it in line with the image intensifier beam. The superimposed surfaces of posterior condyles represent the plane of retrocondylar axis (PCA).

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Figure 4. Intraoperative photograph of right thigh taken from the foot end showing the measurement of angle (A) between the guidewire placed centrally in head neck region (FNA) and the other guidewire placed parallel to retrocondylar axis (GW). Incorrect rotation with FNA lying superior to GW before intersection (a) was corrected by rotating the extremity to keep FNA inferior to GW before the intersection at an angle approximately equal to femoral anteversion (b).

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Figure 5. Preoperative and postoperative AP radiographs of a case with extensively comminuted subtrochanteric fracture of right side. Routine methods of cortical matching to restore limb

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rotation will not be accurate in such cases and the 3rd technique will be helpful in such cases.

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