The patient is placed in beach chair position. The shoulder is supported with pads. The operating table must be radiolucent in the shoulder area; alternatively the corresponding table section is removed. The whole upper arm, including elbow and humeral head must be accessible in two planes for image intensifier control. It is advisable to support the fractured arm on a side rest.

A 3–5 cm long skin incision starts at the tip of the acromion and goes anterolateral. The deltoid muscle is split in line with its fibres. The upper arm is slightly extended in order to gain better access to the humeral head. Through the incision, we can palpate the greater tuberosity and identify the supraspinatus tendon. The tendon is split carefully in line with its fibres. Its attachment on the greater tuberosity is not affected.

As mentioned above, the ideal entry point in the humeral head is depending on the nail design (Figs. 11.​4 and 12.1). The entry portal is identified under image intensification using a Kirschner wire. A cannulated drill placed over the Kirschner wire is used to open the entry site.

The appropriate nail length is determined on the injured arm after fracture reduction. The nail must be inserted just below the articular surface of the humeral head. For adequate alignment and stability, the nail should be as long as possible. The individual characteristics of the endomedullary canal should however be assessed preoperatively. In some patients, the endomedullary canal in the distal third of the humeral shaft is very thin or non-existing. Inserting a nail with force in these patients is contraindicated as it bears the risk of fracturing the distal humerus. For many nail types, specific rulers are available to determine correct nail length and diameter under image intensification.

Insertion of the implant is done by hand with slight rotating movements. The nail is first inserted up to the fracture site. Consecutively, the fracture is reduced carefully and the nail passed beyond the fracture under image intensifier control until it reaches its final position. The nail end must be inserted below the level of the cartilage to avoid implant impingement. Distraction in the fracture site should be prevented by applying manual counterpressure on the olecranon.

We recommend double static interlocking in both the proximal and distal fragment (Fig. 12.2a–d). Proximal interlocking is done near to the shoulder joint. Whatever device is used for interlocking – bolts, screws or blades – stab incisions will open the skin, but further dissection is carried out by spreading the muscle fibres. Caution has to be taken for the branches of the axillary nerve. The bolts or spiral blade should not perforate the articular surface of the humeral head as they will impede free motion and injure the glenoid fossa. If bolts or blade protrude laterally, they also will cause painful impingement. The insertion of two bolts perpendicular to each other enhances rotational stability. In specific nail types, it is possible to use an oblique bolt going from proximal lateral to distal medial, which will enter the medial cortex below the humeral head. This augments stability through better grip and lowers the risk of perforating the articular surface of the humeral head. Some nail types provide higher stability due to fixed-angle interlocking of a spiral blade or screws.

Distal interlocking is done near to the elbow joint. Two bolts are placed through stab incisions from anterior to posterior by free-hand technique using an image intensifier. Small Langenbeck retractors are used to protect soft tissues and avoid damage to the median nerve and brachial artery. Interlocking from lateral to medial is not recommended as there is a high risk of damaging the radial or ulnar nerve.

The patient is preferably placed prone at the ipsilateral edge of the table. The fractured upper arm is placed on an additional arm board or arm rest attached to the table. The elbow is flexed at 90° and the lower arm is hanging down. The hanging forearm restores alignment and avoids malrotation in the fracture. It must be possible to flex the elbow up to 120°. The whole upper arm, including elbow and humeral head should be visible in two planes in the image intensifier.

When the patient is placed in the lateral position, the fractured arm is placed over a foam wedge. It should be possible to bend the elbow joint up to 120°. If the patient remains in the supine position, the fractured arm is placed over the thorax on supporting pads. With the elbow flexed, the upper extremity is held in place by an assistant, who stays on the opposite site of the operation table and holds the hand.

The ability to view the entire humerus in the image intensifier should be checked before starting surgery.

The skin incision begins at the tip of the olecranon and runs about 8 cm upwards. The triceps tendon and distal part of the triceps muscle are split. A triangular bone area above the olecranon fossa and between the edges of the medial and lateral condyles is exposed. The entry portal is located in the centre of this triangle. The elbow joint capsule is left intact.

Three holes, which form the edges of a small triangle, are drilled perpendicular to the dorsal cortex. They are interconnected with a conical burr. We use a set of conical burrs with increasing diameter. While drilling, the angle between the burr and the bone is gradually diminished to end at an angle which is in line with the endomedullary canal. An entry portal of 10 mm width and 20 mm length is created (Fig. 12.3). The proximal cortex is undercut to allow easier introduction of the nail in the endomedullary canal.

A too distal entry portal will damage the elbow joint capsule with periarticular ossifications and limitation of elbow extension as possible consequences.

In retrograde nailing, the nail length is shorter than in antegrade nailing. The nail starts above the olecranon fossa and ends at the surgical neck, leaving the humeral head untouched.

Insertion of the implant is done by hand with slight rotating movements. High stresses can rise on the cortical margins of the entry portal, if it is not large enough or if the nail diameter is selected too big. Fissures, but also supracondylar fractures have been described as a consequence to this! If the nail does not slide in easily by rotating movements, the entry portal must be enlarged, the distal intramedullary canal widened by hand reamers or a thinner nail inserted. It is contraindicated to hammer as this increases the risk of iatrogenic fissures or fractures at the insertion site. The nail is first inserted up to the fracture site. Consecutively, the fracture is reduced carefully and the nail passed beyond the fracture under image intensifier control until it reaches its final position.

Interlocking is crucial for humeral nails as a non-interlocked nail does not provide adequate rotational stability. As in antegrade nailing, we recommend double static interlocking in both the proximal and distal fragment.

Proximal interlocking is done near to the shoulder joint through stab incisions. Further dissection is carried out by spreading the muscle fibres. Caution has to be taken for the branches of the axillary nerve. The insertion of two bolts perpendicular to each other enhances rotational stability. Some nail types provide higher stability due to fixed-angle interlocking of screws.

Distal interlocking is done through the aiming device. Two bolts are placed through the existing incision from posterior to anterior. Free-hand interlocking from lateral to medial is contraindicated as it bears a high risk of damaging the radial and ulnar nerves.

In case interfragmentary compression is planned, double interlocking is performed first at the proximal fracture fragment. An interlocking screw is then inserted in the dynamic hole at the nail base, which is located in the distal fracture fragment. Pushing the screw in the dynamic hole will close the fracture gap and realize interfragmentary compression. Finally, a second interlocking screw is inserted in the static hole at the nail base securing the obtained compression (Fig. 12.4a–f).