Executive Editor: Chris Colton

Authors: Pol Rommens, Peter Trafton

Humeral shaft 12-A1 CRIF

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Glossary

1 Principles top


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General considerations

Acute and pathological fractures can be nailed.

For nailing, the fracture must be situated between the surgical neck of the humerus and 5 cm above the olecranon fossa. The fracture type is of no importance. For proximal shaft and humeral neck fractures, a short humeral nail may be an alternative.

There are many different nails on the market; the main difference between them relates to their locking configurations. Some nails allow compression at the fracture site.

To demonstrate the principles, the illustrations below show the use of a Synthes nail. Some details may not be applicable with other nailing systems.

2 Determining nail diameter and length top

Use the radiographic ruler

Use a radiographic ruler to determine the correct size and length of the nail to be inserted.

The ruler is placed anteriorly on the upper arm over the medullary canal.


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Determine nail diameter

Visualize the medullary canal under image intensification in AP view and compare with the diameters of the marks on the ruler.

The correct diameter of the humeral nail corresponds to the diameter of the mark that fits completely into the medullary canal. Look carefully at the distal humeral canal. It may be narrower than the rest.

In our example, a nail of 7.5 mm diameter is chosen.


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Determine nail length

First, provisionally reduce the humeral fracture.

Next, the ruler is placed parallel to the arm, with the top-of-nail mark at the level of the anticipated insertion site in the humeral head.

Take an AP image intensifier view of the distal humerus together with the ruler.

The humeral nail should be as long as possible in the distal canal, consistent with its diameter. Determine this length with the aid of the ruler.

3 Entry portal top

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Insertion of guide pin

Insert a guide pin through the opening made in the supraspinatus tendon, just at the lateral edge of the humeral articular cartilage, and confirm correct positioning in two planes, using image intensification.


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Location of entry point

Different nailing systems have nails of different shapes, and so may require different entry points. Refer to the manufacturers' operative technique guides for further details.

Insert the guide pin into the proximal humerus.


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Opening entry portal

Open the proximal end of the humerus using a cannulated awl. Insert it over the guide pin.

An entry portal of about 12 mm diameter is recommended.

4 Nail insertion top

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Insertion handle

Mount the insertion handle/aiming guide on the proximal end of the nail using the connection screw.

Ensure that the convexity of the nail curvature points away from the insertion handle.


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Nail insertion

Insert the nail tip into the entry portal. Advance the nail in the proximal shaft fragment using gentle rotatory movements.

Do not use a hammer, as this may increase the risk of fissure or fracture at the insertion site.

Advance the nail just beyond the fracture site.


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Reduction

Use the nail tip as a reduction aid.

After passing the fracture site, adjust humeral shaft alignment, rotation, and length.

Control under image intensification in two different planes.


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Definitive nail position

The nail is then advanced gently until it has reached the desired position. Avoid fracture distraction.

The nail should be inserted completely into the entry hole. The proximal end of the nail must be below the level of the articular cartilage.

The Synthes system has a hole in the aiming jig through which a K-wire may be passed to indicate the top of the nail.

5 Interlocking: General considerations top

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The nail is inserted so that the insertion handle comes to lie in the frontal plane lateral to the humeral head. Static interlocking with two screws on each side of the fracture is recommended.

Proximal interlocking is performed through the insertion handle/aiming guide. Different nailing systems allow static or dynamic locking, with screws being inserted in various planes and directions.

Distal interlocking is performed by a freehand technique. The direction of the distal locking screws is determined by the particular nail being used. Insertion of interlocking screws from lateral to medial should be performed with care to avoid damage to the radial and/or ulnar nerve.

To prevent the nail from backing out, static proximal locking screws are inserted first. Malrotation and/or distraction at the fracture site can then be corrected, prior to distal interlocking.

If a proximal dynamic locking screw is to be inserted to allow interfragmentary compression in nailing of appropriate fracture configurations, the top of the nail must initially lie well below the articular surface of the humerus. This is because interfragmentary compression produces upward sliding of the nail in the proximal fragment, with the risk of subacromial impingement.

6 Proximal interlocking top

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Proximal dynamic interlocking

If dynamic locking is available, place the sleeve system through the hole in the insertion handle/aiming guide corresponding to the dynamic slot of the nail, and make a stab skin incision.

Use a small clamp to spread the tissues to make a track for advancement of the sleeve.

Blunt dissection of the soft tissues and use of the sleeve will prevent damage to the axillary nerve during the drilling procedure.

Advance the sleeve onto the humeral surface.

Drill the hole for the dynamic interlocking screw, taking care that the tip of the drill does not penetrate the joint surface of the humeral head.

Measure the depth of the hole. The ideal length of the screw is 5 mm shorter than the measured length.

Finally, insert the interlocking screw and check for the correct position and length under image intensification in two planes.


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Proximal static interlocking

Place the sleeve system through the hole in the insertion handle/aiming guide corresponding to the static hole of the nail, and make a stab skin incision.

Use a small clamp to prepare a track for advancement of the sleeve through the soft tissues.

Blunt dissection of the soft tissues and use of the sleeve system will prevent damage to the axillary nerve during the drilling procedure.

Advance the sleeve onto the humeral shaft.

Drill the hole for the static interlocking screw, taking care that the tip of the drill does not penetrate the joint surface of the humeral head. If situated distal to the articular surface, the tip of the drill bit may penetrate the opposite cortex.

Measure the depth of the hole.

Finally, insert the interlocking screw and check for the correct position and length under image intensification in two planes.


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Proximal oblique static interlocking

In some systems, as an alternative to double interlocking, one single proximal oblique static interlocking screw may be used.

Place the sleeve system through the oblique hole in the insertion handle/aiming guide and make a stab skin incision.

Use a small clamp to prepare a track for advancement of the sleeve through the soft tissues.

Advance the sleeve onto the humeral surface.

Drill the hole for the screw. If situated distal to the humeral head, the tip of the drill bit may penetrate the opposite cortex, but the drill and screw tip should not protrude far beyond the medial cortex, in order to avoid neurovascular injury.

Measure the length of the hole.

Finally, insert the interlocking screw and check for the correct position and length under image intensification in two planes.

7 Distal interlocking top

Preliminary remark

Correct any fracture distraction or malrotation before distal interlocking. Distal interlocking is always performed using a freehand technique. The insertion of two interlocking screws is recommended. See also the general considerations above. The placement of anterior-posterior screws only is shown here.


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Position of the skin incision

Use the image intensifier and, by gentle rotatory movement of the upper extremity, ensure that the selected interlocking hole appears as a perfect circle.

A sharp skin incision is made over this circle.


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Soft tissue dissection

Use small scissors to prepare a track for insertion of the drill bit.

Blunt dissection of the soft tissues will prevent damage to the median nerve and brachial artery, located medial to the skin incision.


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Pearl: Use small retractors

Small right angle retractors assure protection of muscular, vascular and neurological structures. Make sure that you can see the bone before drilling.

Please note that the retractors reduce visibility under image intensification.


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Drilling

The positioning of the drill tip, its fine adjustment, and the drilling procedure are performed under image intensification.

Many surgeons prefer a radiolucent drill attachment if it is available.


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The radioopaque circles of the radiolucent drill should be centered on the locking hole.

The length of the required screw is measured with a depth gauge.


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Insertion of interlocking screw

Insert the interlocking screw and check for the correct position and length under image intensification in two planes.


Second interlocking screw

A second interlocking screw is inserted as described above.


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Pearl: Place an absorbable suture around the screw

To avoid losing the screw in the soft tissues during insertion and tightening, an absorbable suture is fastened around the screw’s head beforehand.


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Final remark

When interlocking is completed, the definitive position of the implant is checked under image intensification in two planes. Particular notice is taken of the position of the proximal end of the nail and the location and length of all interlocking screws.

8 Nail capping and wound closure top

Cap the end of the nail

Remove the insertion handle/aiming guide and its connecting screw.

Insert an end cap, in order to prevent ingrowth of bony tissue.

End caps of different lengths may be available and may add as much as 15 mm to the overall length of the nail. The top of the end cap should lie just below the articular cartilage, in order to facilitate later implant removal, but must not protrude above the humeral surface.


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Pearl: Using the 0 mm end cap

In some systems a 0 mm end cap, which fits completely within the nail, may be inserted through the insertion handle. To do this, the connection screw has to be removed carefully without moving the insertion handle. The end cap can then be passed through the channel of the insertion handle. This is not possible for longer end caps as they are of a larger diameter.


Wound closure

All wounds are irrigated and cleaned.

The supraspinatus tendon is closed carefully with interrupted sutures.

A drain may be inserted above the supraspinatus tendon. The deltoid muscle, subcutaneous tissue, and skin are closed separately.

For the stab incisions, skin closure only is performed.

v1.0 2006-09-14