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Supracondylar fracture of the humerus- MUA and K-wiring of Flexion pattern fracture

    Overview

    Learn the Supracondylar fracture of the humerus: MUA and K-wiring of Flexion pattern fracture surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Supracondylar fracture of the humerus: MUA and K-wiring of Flexion pattern fracture surgical procedure.
    Supracondylar fracture of the distal humerus is the commonest elbow injury in children. Extension fractures with posterior displacement of the distal fragment are the most frequent. Flexion injuries with anterior displacement of the distal fragment account for approximately 2-3% of all supracondylar fractures. They are generally the result of falls onto the olecranon process (extension injuries occur secondary to fall onto outstretched hand). It is important not to miss these injuries since management is often different to the more common extension variety. Flexion type injuries typically occur in slightly older children (5-8 years compared to 2-4 years).
    Injuries to the brachial artery and median and radial nerves are much more common in extension in extension supracondylar fractures (neurovascular structures are anterior and therefore stretched as the fracture extends) than the flexion type. The commonest nerve injury in flexion type injuries is the ulnar nerve, occurring in 10-20% of cases.
    Closed reduction and percutaneous K wire stabilisation should be attempted as the ideal treatment. However, achieving and maintaining adequate reduction of the fracture by closed means is difficult and open reduction is required much more frequently than for extension type injuries.
    Outcomes are good providing adequate reduction can be achieved. Non union and long term stiffness are very rare.
    Readers will also find of interest the following OrthOracle techniques:
    Fixation of distal third humeral shaft fracture using Synthes LCP extra-articular distal humeral plate
    Open Reduction and Internal fixation of proximal humeral physeal fracture using Synthes Philos plate
    Internal Fixation of Olecranon fracture using Synthes LCP Olecranon plate
    Suture tension-band fixation of olecranon fracture using Arthrex Fibretape sutures

    Indications

    INDICATIONS
    Undisplaced supracondylar fractures are managed in a cast with the elbow flexed just below 90 degrees.
    Displaced flexion supracondylar fractures require reduction. The majority will then be stabilised with percutaneous K wires.
    SYMPTOMS & EXAMINATION
    A thorough neurovascular assessment is mandatory. However, this can be difficult in young children. The radial artery should be felt. Absence of radial pulse is reasonably common in grade III extension supracondylar fractures. The collateral circulation around the elbow is excellent and in most cases the hand will be well perfused, the “pulseless pink hand”. Management of the pulseless pink hand is controversial but is generally agreed that hand function will not be compromised even if the pulse does not return post reduction of fracture. In flexion injuries vascular injury is extremely uncommon. There are no reported cases in the literature. Most neurovascular injuries are due to traction. In extension injuries the median and radial nerves and the brachial artery are at risk of being stretched since they are in front of the elbow. The ulnar nerve is behind the elbow and therefore stretched in flexion injuries. The close proximity of the ulnar nerve to the medial column and medial epicondyle does put it at risk of entrapment in flexion type injuries.
    In the case of median and radial nerve deficits it is reasonable to manage expectantly and observe over a few weeks. Most cases are neurapraxias and will resolve. Whilst ulnar nerve injuries are also frequently neurapraxia, care should be taken to ensure that the nerve is not trapped at the fracture site. This can be done through a small medial incision.
    IMAGING
    Anteroposterior and lateral plain radiographs are mandatory to make the correct diagnosis.
    The Gartland classification is applied to extension supracondylar fractures but can also be applied to the flexion pattern.
    Gartland I – undisplaced
    Gartland II – single cortex (anterior or posterior) intact
    Gartland III – completely displaced.
    Grade IV was aded later. This describes a supracondylar fracture that is completely displaced but with both anterior and posterior instability (denoting that both the anterior and posterior periosteum have torn.
    When assessing the radiograph look to see whether the distal fragment has moved laterally or medially. This may help in determining the best approach if open reduction is required.This is especially in the case of extension supracondylar fracture where posterolateral displacement increases risk of damage to the median nerve and brachial artery.
    When assessing the adequacy of reduction the lateral view is important. On the lateral radiograph the anterior humeral line is extended down the proximal humerus and should intersect the middle 1/3 of the capitellum. Failure to intersect any part of the capitellum suggests unsatisfactory reduction.
    ALTERNATIVE OPERATIVE TREATMENT
    Most surgeons elect to operate on these fractures with the patient in a supine position. Surgery with the patient prone has been described with the arm allowed to hang free over the edge of the operating table with the elbow flexed (Sharafi 2018).
    If closed reduction of the fracture is not possible open reduction is indicated. A medial incision allows access to the medial column and also exploration of the ulnar nerve. A lateral incision may also be necessary. Direct anterior approaches should be avoided.
    NON-OPERATIVE MANAGEMENT
    Grade I or undisplaced fractures can be managed in a cast. By definition these injuries are indistinguishable from extension injuries and are treated in the same manner. Grade II injuries are reduced by extending the elbow and in theory can be managed in a straight arm cast. This is quite uncomfortable for patients and controlling rotation in a straight arm cast can be difficult. In practice most grade II fractures and all grade III will require K wires stabilisation.
    CONTRAINDICATIONS
    There are no contra indications to attempted closed reduction and percutaneous pin stabilisation. Surgeons should be cautious is the presence of ulnar nerve injury since the nerve may be entrapped at the fracture site.

    Setup

    Surgery s performed under general anaesthetic. The consent process should explain that whilst closed reduction and percutaneous stabilisation with K wires is the preferred method, it is possible that open reduction will be required. This would involve medial and possibly also lateral incisions.The patient is placed supine. A tourniquet is mandatory in case open surgery is necessary.

    Operation – 1

    Anteroposterior radiograph of left elbow in 5 year old female. Closed injury. No neurovascular deficit. fracture is seen running across the top of the olecranon fossa. Acceptable alignment in coronal plane.

    Lateral radiograph confirms type II flexion supracondylar fracture of distal humerus.
    The posterior cortex has broken but there is possibly that anterior periosteal sleeve is intact.
    A line extended along the anterior humerus passes behind the capitellum. This is not acceptable and although the fracture would heal the patient would lack full extension of the elbow.

    Patient is in supine position with tourniquet and radiolucent table.The patient is placed in supine position. A radiolucent arm table is required and the patient has to be advanced far enough over the arm table so that satisfactory images can be acquired.
    A tourniquet is placed as far up the arm as possible to allow access to the elbow.

    Screen fracture under image intensifier C arm to determine whether reducible.The fracture should be examined and screened prior to skin preparation and surgery. This will allow determination of whether closed reduction is possible.
    The image intensifier is advanced below the radiolucent arm table. Surgeon and assistant/scrub nurse will sit opposite each other and either side of the image intensifier.
    The patient will need to be brought as far as possible to the edge of the operating table to allow sufficient room to image the elbow.

    Note any areas of skin bruising or tethering, especially medially, which can indicate ulnar nerve injury or that it is at riskThe arm is held in flexion. Note bruising over medial side of the elbow. This corresponds to the proximal bone spike, indicating that at the time of injury there will have been a vagus force in addition to flexion.
    Beware ulnar nerve injury and entrapment in this scenario (particularly if there is pre operative evidence of neurological deficit). The nerve may have subluxed anteriorly in front of the proximal fragment and be running through the fracture site anterior to posterior.

    With the elbow flexed and externally rotated fracture displacement is exaggerated.

    Determine whether fracture reduction is better with internal rotation of the arm or external rotationThe elbow is extended and internally rotated (pronated).

    In this position fracture reduction is good. This confirms that the fracture can be reduced closed. Note how the anterior humeral line intersects through the mid point of the capitellum.
    The surgeon should be aware that insertion of percutaneous K wires is difficult when the arm is held extended (access is blocked by the wrist extensor muscles) and open approach may be necessary. Proceed to skin prep and draping of the extremity.

    Once an appropriate reduction manoeuvre is identified, drape the arm well above the elbow to allow open exploration if required.The arm is draped free. Ensure that there will be enough room to access the fracture site should open reduction be required. In order to identify and protect neurovascular structures (especially ulnar nerve) incisions will need to extend proximal to the fracture site by 2-3cm.
    Once skin prep and draping has been completed advance the image intensifier (draped) once more beneath the table. Assistant/scrub nurse should sit opposite the operating surgeon.
    Screen the arm again in the position identified previously. In this case internal rotation, extension and pronation.

    Once draped and using II, if the fracture can be reduced with the elbow extended attempt gently flex the elbow and note if reduction can be maintained. K wire insertion is much easier in this position.In order to maintain reduction apply axial force along the forearm to maintain extension at the fracture site (while flexing the elbow).
    Note how the upper arm is stabilised with the surgeons other hand. This is a modification of the ‘push – pull’ technique described for fracture reduction.

    The initial wire to be inserted is placed medially if reduction is better in external rotation, and lateral if in external rotation.Confirm that satisfactory position has been achieved. This position is suitable for insertion of percutaneous K wires.
    If reduction cannot be maintained an open approach should be employed.
    A medial approach will always be necessary to ensure that the ulnar nerve is not trapped at the fracture (see below).
    A lateral incision is frequently also necessary. This should extend from the lateral epicondyle proximally to the fracture site. It will be parallel to the humeral shaft.

    Take a 2mm K wire loaded onto the driver (in a young patient less than 2yrs a 1.8 or 1.6mm K wire may be sufficient). Lay this on the skin in the predicated path that will be taken, then image.In this case the fracture reduction is optimal with the arm internally rotated. In this position access to the lateral column is easier and hence the lateral wire is inserted first.
    If reduction is better with the arm externally rotated it would then be appropriate to start with the medial wire.

    If correctly positioned the entrance point in the bone will be the posterior 1/3 of the capitellum. The K wire should be passed up the lateral column.

    Once an appropriate path for the first K wire has been identified, mark intended path of wire on the arm with a marker pen.Draw a line along the path of the K wire with a marker pen (A). It is also helpful to mark the olecranon (B).

    Make a small stab incision with a size 15 blade for insertion of the wire.
    It is not possible to obtain an AP view of the elbow because the fracture reduction will be lost.
    A small stab incision is made approximately 2/3 of the distance between the olecranon and the lateral epicondyle, prior to wire insertion.

    A small stab incision is made approximately 2/3 of the distance between the olecranon and the lateral epicondyle, prior to wire insertion.Check the incision point with II. Note that it is distal to the capitellum.

    The Lateral wire is inserted under II control, advancing across the lateral column and fracture site The angle of insertion is approximately 25-30 degrees in the coronal plane. This corresponds to a path up the lateral column.

    Note how the K wire path is parallel to the anterior humeral line and along the lateral column. The entrance point in the lateral column is just behind the ossification centre of the capitellum in the lateral view. The wire has been passed across the fracture.
    If maintenance of fracture reduction is difficult a K wire can be temporarily inserted in the distal fragment and used as a ‘joystick’ prior to definitive stabilisation.
    The entrance point in the lateral column cannot be checked until the wire has been advanced across the fracture because rotating the arm will result in loss of reduction.

    Once the K wire is across the fracture by 1-2cm the elbow can be partially extended and rotated to obtain an AP view under the II.

    Check AP and lateral position once the first K wire is across the fracture site Satisfactory position. The K wire has good distal purchase. It has been passed through the capitellum and up the lateral column. At this point it has not engaged with the medial cortex proximally. Optimum position will result in the wire passing through the middle or lateral 1/3 of the ossification centre of the capitellum.

    It is a good idea to shorten the K wire slightly to avoid injury to the surgeon/assistant. Use heavy wire cutters.

    Externally rotate arm and mark the medial epicondyle, which is being approached after the lateral column has been stabilised.The elbow has now been externally rotated. Mark the medial epicondyle and proposed incision. A small medial incision of approximately 1-2cm should be used to avoid iatrogenic injury to the ulnar nerve.
    This ‘mini’ approach can be extended proximally if necessary to make a formal approach to the fracture and ulnar nerve.

    Make 1-2cm incision over medial epicondyle, to identify the medial epicondyle and thus avoid iatrogenic injury to the ulnar nerveIt is not generally necessary to open the fracture site or expose the nerve unless fracture reduction is not satisfactory. Tourniquet does not generally need to be inflated since visualisation of the epicondyle is easy. If the wound has to be extended to formally explore the ulnar nerve or open the fracture site the tourniquet should then be inflated.

    Having made incision through skin and fat with size 15 blade use blunt dissection to identify the epicondyle.

    Identify the medial epicondyle by blunt dissection. The ulnar nerve will run behind the epicondyle.The epicondyle is an apophysis. It is cartilaginous and will be a white colour. It should be visualised. An assistant should retract the surrounding tissues with cats paw retractors.

    Operation – 2

    Place the medial K wire directly on the medial epicondyle under direct visualisation to ensure the ulnar nerve is not at risk.It is not necessary to formally identify the ulnar nerve. It is important to directly place the medial K wire on the epicondyle.

    Check the position with II. Note that by about 7 years of age there will be an ossific nucleus in the medial epicondyle.
    Confirm the angle that the medial wire should be inserted to engage the medial column.

    Externally rotate the elbow to obtain a lateral view. Note how the medial wire seems to be posterior compared to the lateral wire. This is correct.

    The medial wire is inserted with the elbow slightly flexed, under II control.This ensures that the ulnar nerve does not sublux anteriorly and should not be in danger of iatrogenic injury.

    Advance the medial K wire across the fracture site and check position with II. Ideally the medial and lateral wires should be widely spaced at the level of the fracture as this provides optimal stability.Check position on image intensifier. Wires should be separated as much as possible at fracture.
    The wires should cross proximal to the fracture.

    Once a satisfactory position is achieved advance both medial and lateral wires across the opposite cortex.

    Check AP position on II. Check that both cortex’s have been engaged.

    Check fracture stability after wire insertion with the arm internally and externally rotated.It is important to assess stability. Externally rotate the arm to obtain a lateral II view. Note that fracture remains reduced.

    Then swing arm into internal rotation to ensure that there is no movement of the fracture.
    If the fracture moves when the arm is rotated it suggests that one or both wires are not engaged in both proximal and distal fragments. Either the wires should be replaced or a third wire inserted (from lateral side).

    The wound can be closed around the K wire. However if the wire is shortened it can then exit via a percutaneous wound separate from the operative wound.

    Elevate the skin over the wire.

    Make a small incision over the wire tip.

    Flex the elbow to around 60 degrees and bend the tip of the wire with fine wire benders.

    Close wound and bend K wires proud of skin, to facilitate later removal.The wound is closed with interupted 4/0 monocryl.

    Bend the lateral wire with fine wire benders.

    Cover both wires with jelonet or mepotil.

    Pad the wires with gauze.

    Apply above elbow backslab.An above elbow backslab is applied with 70 degrees flexion of the elbow. Include the hand. Forearm in neutral pronation/suppination.

    Post Operative

    Patients will generally be able to be discharged home the same day as the surgery. Check neurovascular status prior to discharge. A broad arm sling allows the arm to be rested. Clinic review at 1 week. If necessary backstab cast can be reinforced.
    Fractures will be stable at 3-4 weeks. K wires are generally removed in clinic at this stage and the arm mobilised. Physiotherapy is not required and can result in rebound stiffness. Parents are warned that whilst a functional range of movement rapidly returns, full range of movement may take 6-8 weeks post removal of cast and wires.
    Contact sports should not resume until 6 weeks post injury.

    Recommended Reading

    Bone healing is reliable is both flexion and extension supracondylar fractures. There are no reported cases of non union in the published literature. The published literature regarding flexion supracondylar fractures is sparse. However, complications do seem to be more prevalent than for extension fractures. Malunion is more common which may be a reflection of the fact that reduction and stabilisation is more difficult.
    Open reduction is necessary for approximately 1/4 of flexion supracondylar fractures. The more displaced the initial fracture the more likely open reduction will be necessary. Flynn (2017) found that associated ulnar nerve deficit at presentation was strongly associated with need for open reduction. Approximately 10-20% of flexion type supracondylar fractures have coexisting ulnar nerve deficit.
    Flynn K, Shah A, Brusalis C et al. Flexion type supracondylar humeral fractures. Ulnar Nerve injury increases risk of open reduction. Journal Bone Joint Surg. 2017; 99(17): 1485-1487.
    Kuoppala E, Parviainen R, Pokka T et al. Low incidence of flexion type supracondylar humerus fractures but high rate of complications. Acta Orthopaedic 2016;87(4): 406-411.
    Babal JC, Mehlman CT, and Klein G. Nerve injuries associated with pediatric supracondylar humeral fractures: a meta- analysis. J Pediatr Orthop 2010; 30: 253–263.
    Babal JC, Mehlman CT, and Klein G. Nerve injuries associated with pediatric supracondylar humeral fractures: a meta- analysis. J Pediatr Orthop 2010; 30: 253–263.
    Sharafi M, Presedo A, Rabie H, Nabian MH. Flexion-Type Supracondylar Humerus Fracture: A Review on Reduction Techniques. J Orthop Spine Trauma. 2018 September; 4(3): 54-8.
    Sharma A. The flexion type supracondylar humeral fracture in children. A review. Journal Bone Joint Surg. 2019; 7(4): p e6.

    Reference

    • orthoracle.com

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