Date: Sun, 11 Nov 2001 21:20:01 EST

Subject: Distal Femoral Locking

Are there any tricks for locking a femoral intramedullary rod distally? I have difficulty with obtaining a lateral of the distal femur, using radiolucent drills, etc.

Are there any innovative solutions to this problem?

Mike Messieh

Date: Mon, 12 Nov 2001 08:16:05 -0500

From: Clifford B. Jones, M.D.

If you do not have a good c-arm or c-arm tech, you are in trouble. The problem may come from the rotation of the nail when you insert it. If you place the nail in too much internal rotation, the c-arm can not rotate enough to allow for perfect circle vision. Some innovative solutions have come from C Krettek in JOT concerning a variable arm for the distal interlock. I have found practice and the free hand technique to the easiest. Good luck.

Cliff Jones

Date: Mon, 12 Nov 2001 07:32:39 -0600

From: Anglen, Jeffrey

Somebody showed me a system at the AAOS meeting a couple years ago that involved a nail with a magnet as part of an inner rod just at the level of the interlock holes, and an external guide that was basically a compass, which pointed the way to the hole. I thought that was pretty innovative, but I haven't seen it or heard about it since.

I think the realistic solution is practice. The freehand technique with a guidewire and cannulated drill is pretty reliable after the first hundred or so.

Jeffrey O. Anglen, MD FACS
Associate Professor of Orthopaedics
Chief, Orthopaedic Trauma Service
Columbia, MO

Date: Mon, 12 Nov 2001 09:11:08 -0600

From: Steven Rabin

Somebody showed me a system at the AAOS meeting a couple years ago that involved a nail with a magnet as part of an inner rod

This is the Magellan nail, which I have used and it does work - my orthopaedic second year resident put 2 locking screws in in less than 20 minutes. There were however problems due to its modular design and more hassle factor proximally. The company went bankrupt, but it has since been revived by another company although i don't recall the new owners.

Please check out my article: Tips of the Trade: Inserting Distal Screws into Interlocking IM nails - revisited: Methods to Make it Easier. From Orthopaedic Review, 22(9): 1059-68, Sept. 1993.

Hopefully, it will help.

Steve Rabin
Chief Ortho Trauma, Loyola

Date: Mon, 12 Nov 2001 14:56:53 -0000

From: Nuno Craveiro Lopes

Best solution is not to lock distally!

I found this nail promising.
http://www.disc-o-tech.com/content/news.asp

Nuno Craveiro Lopes
Almada, Portugal

Date: Mon, 12 Nov 2001 09:51:02 -0600

From: Adam Starr

Best solution is not to lock distally!

I disagree with that.

Best solution is to learn how to lock distally so you can fix the fracture.

Practice, practice, practice.

If you don't do too many femur nails in live people, practice your technique on cadavers.

At our center, we use a free-hand "perfect circles" technique. I've never thought the radiolucent drills added much.

The things that help the most are a good fluoro tech, and sharp drill bits. If your bit keeps slipping, you might get a sharper bit. I've also seen people tap an awl in the right spot to create a little hole for the drill bit to start in.

Once you puncture the near cortex, stop drilling, yaw your hand and the drill to one side and re-check the image. You can tell if you're going to be able to hit the screw holes or not. Most of the time, if you're at all close on the near hole, you can correct if need be and hit the far hole.

Good luck,

Adam Starr
Dallas, Texas

Date: Mon, 12 Nov 2001 09:15:17 -0600

From: Frederic B. Wilson, M.D.

Nuno,

I would have to disagree. I think the potential for rotational deformity outweighs the inconvenience of having to become facile with distal interlocking. The best solution I know is careful positioning before initiating the IM nailing, to include scout views of the femur with the c-arm to insure that everything can be seen. During the interlocking screw placement have the c-arm operator go to Mag1 or 2 before trying to make perfect circles. Then do corrections in the longitudinal axis to get the widest diameter before making corrections in the cross-sectional axis to convert the "football" to a "soccer ball".

Date: Mon, 12 Nov 2001 13:05:58 -0500

From: Kevin Pugh

At our institution, distal locking takes about 3-5 minutes per screw... Freehand technique...and the juniors do it with supervision.

There is no replacement for repetition. If all of the time energy and money spent trying to come up with an easier method was invested in learning how to do it, we wouldn't be having this discussion.

Date: Mon, 12 Nov 2001 22:33:48 +0200

From: Mehmet Arazi

Dear list members:

I totally agree with Dr Starr. For tracing near cortex, we used a simple instrument like in this web site http://innomed.net/InnoTra1.htm#10TRAnchor

With freehand (perfect circles) technique and using this instrument, it is very easy for me and also my residents.

Best regards

M. Arazi MD,
Lecturer,
Selcuk University Medical Faculty,
Dep Orthop & Trauma, TURKIYE

Date: Tue, 13 Nov 2001 11:12:00 -0500

From: David Goetz

Check out the new Zimmer drills for distal fixation. They are brad point type with a long center spike, they don't slip as you walk the cortex and even let you angle back for a clear view of the absolute center of the circle. Regular bits, even if sharp will move a little when drilled, these won't.

David R. Goetz MD

Medical Director, Orthopaedic Trauma

Date: Wed, 14 Nov 2001 01:23:27 +0500

From: Alexander Chelnokov

Hello Adam,

AS> bit. I've also seen people tap an awl in the right spot to create a little hole for the drill bit to start in.

I started to perform interlocked nailing only this year (the first case was presented here) without even a proximal locking device, so lost many "blood, sweat and tears". Some Ilizarov background gave me an idea to prepare a "flexible drill" - a tip of standard 2 mm wire was flattened out to 4 mm and sharpened as a diaphyseal wire. It is easy to place the tip to the "perfect circle" keeping hads very far from intensifier rays. After drilling of the near cortex it can be replaced by a usual drill bit - no problem to locate 4 mm hole at the bone surface. Maybe it could be useful for someone else.

Best regards,

Alexander N. Chelnokov
Ural Scientific Institute of Traumatology and Orthopaedics
Ekaterinburg 620014 Russia