Fixation of distal third humeral shaft fracture using Synthes LCP extra-articular distal humeral plate

This 20 year old left handed patient sustained the above closed injury when he lost his balance performing squats. He is normally fit and well and there was no neurological deficit at the time of injury.
The radiographs show a spiral fracture of the humeral shaft at the junction of the distal third of the humerus. There is no comminution or intra-articular extension. No further imaging was required for surgical planning.
The distal fragment tends to sit in relative internal rotation and varus due to the weight of the forearm as the arm rests against the body. The pull of the muscles spanning the fracture (biceps, brachialis and triceps) results in shortening of the fracture.

Under general anaesthetic the patient is set up in the lateral decubitus position.
A short ulnar gutter support is applied to support the distal humerus.
Clamps are checked to ensure that the supports are fixed and that there are no pressure areas on the torso.
The mobility of the arm is checked to ensure adequate imaging of the humerus (AP & Lateral views) are with fluoroscopy, particularly with clearance of the table and clamps.

Under antiseptic technique, local anaesthetic with adrenaline 1:200000 is infiltrated along the surgical approach to minimise bleeding.

The whole upper limb is prepped and U drapes are applied up to the level of the axilla to maximise the sterile field.
The hand is covered in a stockinette and wrapped with four inch crepe to isolate the hand. This also keeps the hand clear of any blood.

The radial and ulnar aspect of the upper arm is marked as an aide for orientation during the surgery (A & B)
The landmarks are identified, including the medial and lateral epicondyles. The ulnar nerve is palpated. The outline of the olecranon is palpated and marked.
A longitudinal posterior midline incision is marked, centred over the fracture site. The incision extends distally, curving radially to avoid aligning the incision over a “weight-bearing” surface.

The incision is made using a 15 surgical blade through skin and subcutaneous fat down to the level of the triceps muscle fascia.
Once the appropriate plane at the level of the triceps fascia is identified, fasciocutaneous flaps are raised to allow adequate exposure of the triceps. As depicted, the surgical blade is applied obliquely against the tissues to stay in the correct plane and to not incise into the triceps fascia. If done correctly, the areolar tissue lifts off easily with very little bleeding.
This exposure is developed through the whole length of the incision. Retractors help to expose the field of view. Diathermy to bleeding vessels is applied to achieve haemostasis. Stay sutures using 1 vicryl at the corners of the wound help maintain exposure.

This dissection is continued to the lateral edge of the triceps (A) at the level of the lateral intermuscular septum.
The triceps is mobilised medially off the posterior surface of the humerus. This is usually commenced at the distal humerus. The humerus is palpated and residual fibres of triceps are dissected off the bone using a periosteal elevator.
As the dissection takes you proximally, care needs to be taken to identify the radial nerve as it exits through the lateral intermuscular septum (marked with forceps) from the posterior to the anterior muscle compartments.
The territory of the nerve can be identified easily by the associated vascular bundle.

At this stage, care is taken to dissect using McIndoe scissors under direct vision. The muscle fibres from the medial head of triceps are freed up off the bone.

The bone is better exposed distally using a periosteal elevator.
Once the triceps muscle has been mobilised sufficiently, a Hohmanns retractor can applied over the ulnar aspect of the humerus to aid exposure. Care is taken to ensure that the retractor is against the surface of the bone to ensure there is no injury to the ulnar nerve which lies immediately adjacent.

Cautious dissection is continued proximally as the radial nerve is yet to be identified.
The radial nerve originates from the posterior cord of the brachial plexus and is supplied by nerve roots from C5 – T1. It runs posterior to the axillary artery. In the arm, it runs behind the brachial artery and then passes through the triangular space to reach the spiral groove of back of the humerus. It travels with profunda brachii artery, between the lateral and medial heads of triceps until it reaches the lateral side, where it pierces the lateral intermuscular septum to reach the anterior compartment of the arm. It descends down to cross the lateral epicondyle of the humerus where the nerve terminates by branching itself into superficial and deep branch which continues into the forearm.
The radial nerve gives out motor branches to supply the long head, medial head, and lateral head of triceps. After it emerges out from the spiral groove, it supplies the lateral half of brachialis, brachioradialis and extensor carpi radialis longus.
With regard to sensory branches above the spiral groove, the radial nerve gives off posterior cutaneous nerve of the arm which supplies the skin at the back of the arm. In the spiral groove, it gives off lower lateral cutaneous nerve of the arm and posterior cutaneous nerve of the forearm. The radial nerve also gives articular branches to supply the elbow joint

The fracture site is identified and mobilised. The periosteal elevator aids clearing the bone from muscle fibres and allows delineation of the fracture edges. A reduction clamp allows control of the distal fragment.

The fracture end is delivered and clear of soft tissues that may encroach on the fracture site.

The canal is curetted to freshen up the fracture surface and to clear any debris.

The fracture site is also irrigated with normal saline to remove further debris.

Any fracture haematoma is cleared to allow clear visualisation of the fracture and to assist its anatomical reduction.

Once the haematoma has been cleared, the distal extent of the proximal fragment can be identified (elevated by the periosteal elevator).

Once cleared, the fracture can be reduced and held using the Hey Groves bone clamps. Care is taken to avoid entrapping the ulnar or radial nerves.
Usually, by this stage the radial nerve has been identified and protected.
The ulnar nerve originates from C8-T1 nerve roots and form part of the medial cord of the brachial plexus and descends medial to the brachial artery. At the level of the insertion of coracobrachialis, the ulnar nerve pierces the medial intermuscular septum and enters ther posterior compartment of the arm. It runs distally along the medial edge of triceps and passes medial to the medial epicondyle in the cubital tunnel.
Motor branches include flexor carpi ulnaris and the medial half of flexor digitorum profundus. Sensory branches include the palmar and dorsal branches. These are all given off below the elbow.

Due to the large surface area of the fracture site, the decision was made to reduce the fracture anatomically and stabilise the fracture using 2 lag screws.
This image shows the near cortex being over-drilled using a 3.5mm drill bit (know as the pilot hole). This is drilled using a universal jig
The positioning of the screws can either be placed through the plate or medial or lateral to the plate. Either way, careful planning prior to drilling is required to ensure that the screw does not impinge on plate positioning and that the screw traverses the fracture site as perpendicular to it as possible.
If planning to place a lag screw through the plate, it can be difficult aligning the plate on the bone in a mobile fracture but it is largely determined by the fracture characteristics.

Once drilled, the universal drill guide is inserted into the 3.5mm pilot hole and a smaller 2.5mm drill hole is made in the far cortex.

The far cortex is drilled using the 2.5mm drill. Care is required to only just breach the distal cortex and not overshoot it.

The near cortex is countersunk to allow even distribution of forces generated by the screw head on the bone when it is eventually inserted and the fracture compressed.

A depth gauge is used to determine screw length.

The drill hole needs to be “tapped” in most adult bone.

When the cortical screw is applied, there should be good hold in the far cortex with compression at the fracture site.
Maintenance of reduction is checked to ensure that the lag screw position does not apply a deforming force to the reduction.

Once satisfied, the process is repeated for a second lag screw. This is optional and dependent on fracture pattern, length and stability.

This images show clearly the lag screws in position in a lateral to medial orientation so as not to impinge on plate placement.

Once stabilised, any bone reduction clamps can be removed.
The periosteal elevator is used to raised the soft tissue subperiosteally proximally.
The medial head of triceps lies between the radial nerve and the humerus, thus protecting it from iatrogenic injury as long as the dissection remains subperiosteal.

The appropriate sized Synthes extra-articular distal humeral plate is chosen, allowing 3 to 4 screws to be applied either side of the fracture.
Note, this image depicts a 6 hole plate for demonstration purposes, although an 8 hole plate was used for this operation.
The available sizes of the plate are :
4 hole – 122mm
6 hole – 158mm
8 hole – 194mm
10 hole – 230mm
12 hole – 266mm
14 hole – 302mm
Note that the longer plates may not be available “on the shelf” and may need to be ordered in.

The 2.8mm locking sleeve can be applied to the plate to allow easier manipulation and positioning of the plate on the bone.

The plate is slid proximally in the subperiosteal pocket under the triceps muscle created by the periosteal elevator.

Care is taken to position the plate distally so that the plate or the orientation of the screws does not impinge on the olecranon fossa or the elbow joint.
The distal limb should lie over the dorsal to dorsolateral aspect of the lateral column.
Bending irons may be used to contour the plate to allow it to conform to anatomy. However, in the author’s experience, this is rarely necessary. Once satisfied, it can be temporarily secured using Hey Groves clamps as shown here.

A calibrated 2.8mm drill is applied to the distal locking sleeve. Due to the distal location of the screws, these are usually unicortical and the far cortex (or joint) is not breached.
The measurement is taken against the locking sleeve from the drill bit and the locking screw is applied using a Stardrive screwdriver with torque limiter, once the locking sleeve is removed.

Supplementary locking screws can be applied to secure the position of the plate after ensuring that the plate is centred on the bone proximally.

My experience is that, in variation to the Synthes described operative technique, the plate seems to sit better on the dorsal aspect of the humerus, and the locking screws are therefore orientated postero-anteriorly as opposed to more obliquely.
The most distal screws may only be unicortical to avoid joint penetration, but more proximal screws on the lateral column tend to be bicortical.

Once the plate is stabilised distally, attention is turned to stabilising the plate proximally.
If the fracture and plate are low enough, the whole procedure can be performed through a lateral triceps window, with care taken to identify and protect the radial nerve when retracting triceps muscle medially.
However, with longer plates, the surgeon prefers to locate the radial nerve proximally using the window between the long and lateral head of triceps proximally. The triceps muscle is allowed to sit back in its natural position.

The orientation of the proximal triceps muscle fibres are assessed to identify the interval between the long and lateral head of triceps.
The fascia incised in the midline between the 2 heads.

This plane is developed using McIndoe scissors using a combination of blunt and sharp dissection.
It is best to develop the interval from superficial to deep with care taken to identify the radial nerve when progressing through the layers.
B – Lateral head of triceps
C – Long head of triceps
R – Radial nerve (located at base of approach)

Once the radial nerve has been identified, it can be mobilised medially or laterally to allow safe deployment of the drill and drill sleeve. A vascular sloop is a useful tool for holding the nerve gently retracted.

A carefully placed Hohmann’s retractor is useful to retract the muscle and allow direct visualisation of the nerve and plate.

The same required steps of measuring, tapping and screw application are performed.

A sloop was passed round the radial nerve to facilitate its mobilisation.
This image shows the close proximity of the radial nerve to the plate and screw.
The diameter of the radial nerve can vary in individuals. If it appears smaller that normal, it is worth considering whether the radial nerve has a high take off and may have multiple branches that need to be identified before proceeding with fixation.

Supplementary locking screws can be applied proximally.
Care needs to be taken when applying the locking sleev so as not to damage the radial nerve.

Once fixed, the plate should sit well centred on the humerus.

The image intensifier is covered with sterile drapes and fluoroscopic images are taken. to ensure satisfactory fixation and plate application. One should specifically ensure there is no screw penetration into the joint.

The intra-operative AP fluoroscopic images show that the fracture has been adequately reduced and aligned using 2 interfragmentary lag screws and the plate used as a neutralisation plate.

The distal AP fluoroscopic images show that the contour of the plate allows adequate hold in the distal fragment whilst sparing the olecranon fossa. Clearly there is no possibility of the metalwork impinging on the olecranon fossa and inhibiting terminal extension.

The lateral intra-operative fluoroscopic images show that there is six cortices of hold proximally and is well away from the fracture site.
The reduction is confirmed to be near anatomical and is fixed with 2 lag screws.

The lateral intra-operative fluoroscopic images show that there is adequate fixation of the distal fragment and the screw clearly do not enter the elbow joint.
With respect to this image, the plate can be applied more distally if required. However, this was not necessary for this case.

The wound is irrigated thoroughly with normal saline before closure.
Note that the soft tissues are regularly irrigated throughout the procedure to prevent them from drying out.

Once the retractors are removed, the triceps muscle covers most of the plate and is not usually prominent.

The distal end of the plate is cover by approximating the triceps fascia to the lateral border of triceps using number 1 vicryl.
It is not necessary to approximate it for the whole length of the lateral window approach.

The wound is closed in layers using number 1 vicryl for the triceps fascia.

The fat layer is closed using 2-0 vicryl.

The skin is closed using 3-0 monocryl suture.

The arm is cleaned and dressed.

Half inch steristrips are used to protect the wound and a dressing is applied over the top.
A wool and 6 inch crepe bandage usually provides sufficient post-operative splintage, a backslab not usually being applied unless there is a concern regarding stability of the fixation.

These were the final radiographs 6 months post surgery.
The fracture is radiologically united and there is remodelling at the fracture site.
The patient was asymptomatic with a range of motion from 0-140 in the flexion-extension plane and full pronosupination.