/

Technique: Internal fixation of 5th metacarpal neck fracture (Synthes LCP plate)

    Overview

    Learn the Internal fixation of 5th metacarpal neck fracture (Synthes LCP plate) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Internal fixation of 5th metacarpal neck fracture (Synthes LCP plate) surgical procedure.
    Metacarpal neck fractures are very common in the hand. The “Boxer’s” fracture in the 5th metacarpal neck is one of the commonest injuries that present to a Hand surgeon. Most of these injuries can be treated conservatively and heal satisfactorily with no functional deficit. However, some present with rotational deformities that need correction for an optimal outcome. A handful of these also present with other concomitant injuries in the hand, which cannot undergo appropriate rehabilitation until the metacarpal neck fracture has been adequately stabilized. Many surgical techniques have been described for reduction and stabilization of this fracture with varied risks and benefits. Open fixation with plates and screws affords the most reliable reduction and a stable construct for immediate mobilization.


    Indications

    Indications:
    Intervention with reduction and stabilization of a 5th metacarpal neck fracture is indicated in the following scenarios:
    Open fractures
    Fractures with rotational deformity
    Comminuted and unstable fractures
    Presence of associated injuries in the same hand requiring early rehabilitation
    Angulation more than 70 degrees. (Although angulation at fracture site has been extensively studied, this one feature in isolation has not been found to be significant for functional outcome.)
    The 2 mm locking plate (Synthes® LCP Compact Hand Set) allows for open reduction of the fracture and provides durable stability by bridging the fracture fragments. The hand can be mobilized immediately with minimal dressings.
    Presentations and findings:
    An axial loading force to a clenched fist causes these injuries. This produces a flexion vector on the metacarpal, which succumbs at the neck. The common mechanism is a punching injury and hence the infamous eponym of “Boxer’s fracture”. They can also coexist with high-energy injuries such as road traffic accidents – as in this case.
    The patient presents with pain and swelling over the dorso-ulnar border of the hand. There is tenderness over the neck of the metacarpus and movements of the finger may be restricted with pain. A common finding is an apparent extensor lag of the small finger at the metacarpophalangeal joint. Presence of any rotational abnormality should be evaluated and documented. Ask the patient to flex all fingers together and look for any scissoring. It is important to remember that the small finger naturally curls radially and points towards the scaphoid tubercle at the wrist. Comparison can be made with the opposite uninjured hand.
    Plain radiographs are essential to confirm the diagnosis and plan the management. I always request for three radiographic views of the hand– Anteroposterior, lateral and oblique. The fracture pattern and location, the displacement and the comminution are noted. Associated injuries should always be looked for and are commonly seen involving the base of the 4th and 5th metacarpals.
    Alternative methods of treatment:
    Conservative with closed reduction followed by plaster immobilisation – Unfortunately, this prevents early rehabilitation of the associated injuries in the hand. In addition, a plaster cast is inadequate to maintain a reduction in comminuted fractures of the neck.
    Percutaneous wiring techniques– These range from longitudinal intramedullary wires, transverse intermetacarpal wires, crossed wires and Bouquet wires. Although these techniques are less invasive, they are not suitable for stabilization of comminuted fractures.
    Intramedullary screw fixation – This is a relatively new technique using headless scaphoid screws to achieve stabilization and permit early rehabilitation. Comminution, however, is a contraindication for this procedure.

    Setup

    Informed consent is an important part of the procedure and the risks and benefits should be clearly explained to the patient. The metalwork lies in close proximity to the articular surface under the extensor tendon hood at the MCP joint. The patient should, therefore, be always counseled regarding the risk of tendon adhesions and stiffness necessitating removal of metalwork after the fracture is healed.
    I prefer regional anaesthesia with axillary block for this procedure. The patient is placed supine with the limb extended on an arm table. Upper arm tourniquet is applied and inflated after exsanguination. A prescrub is performed followed by a sterile prep with Chlorhexidine. A lead hand is used to stabilize the hand. I routinely administer a single dose of antibiotics for this procedure.

    Operation

    A dorsal longitudinal incision is planned overlying the metacarpus. Some surgeons advocate a lateral approach and fixation. However, I think that this is unsuitable for a fracture of the neck, as it does not allow for adequate distal fixation with 2 screws. Additionally, a laterally positioned plate on the 5th metacarpal is uncomfortable in a normal resting position of the hand on a table.

    The skin is incised with a No.15 blade. The subcutaneous tissue is incised with sharp dissection and the skin flaps retracted. The extensor tendons to the small finger are exposed immediately beneath the subcutaneous tissues. The dorsal cutaneous branch of the ulnar nerve lies adjacent to the ring finger extensors and does not interfere in this incision.
    Note the bruising suggestive of the underlying fracture.

    The metacarpal bone is approached through the interval between EDC and EDM. Incision is made with the blade right onto the bone, dividing the periosteum.
    The extensor hood overlying the metacarpophalangeal joint is partially incised. The incision needn’t expose the articular surface of the head of the metacarpus unless the fracture extends into the joint.
    EDC – Extensor Digitorum Communis (Small finger)
    EDM – Extensor Digiti Minimi

    A periosteal elevator is used to elevate the periosteum off the bone. Care should be taken to prevent devitalizing the small, comminuted fragments. I always attempt to retain the soft tissue attachments to these fragments.

    The metacarpal bone is realigned with traction and without attempting anatomical reduction of each small, comminuted fragment. Special care is taken to correct the rotational malalignment.
    If the fracture is not comminuted, Jahss manoeuvre with flexion at MCP and PIP joints, will reduce the fracture in most instances.

    The Synthes®2 mm LCP Compact Hand Set contains a variety of plate designs. The plates all contain options for locking and non-locking screws. The condylar Y-plate and the T-plate are best options for a neck fracture, as they both allow for placement of 2 screws in a transverse plane in the small distal fragment. A straight plate is more suitable for a fracture in the shaft.
    The set contains a full complement of locking screws (green) and non-locking screws (golden).

    A locking T-plate is chosen in this instance. The plate is cut into the appropriate size and contoured to the shape of the bone.

    The horizontal limb will allow insertion of 2 locking screws in the transverse plane for the small distal fragment. The vertical limb should allow for at least 2 screws in the proximal fragment.
    The bones in the hand are small and adequate stability can be attained with only 2 screws on each side of fracture. This is in contrast to the classic AO principles (3 screws and 6 cortices on each side)

    The plate is placed on the realigned metacarpus, bridging the comminuted segment. The distal edge of the plate lies in the subcapital area just below the articular surface of the head.

    The locking guide facilitates the drilling of a pilot hole in the distal fragment. The guide should be well screwed in or else the final screw does not seat in properly into the plate.
    Tip: The guide can be screwed into the plate before placing it on the bone. This avoids struggling in the confined space of the wound. This will also provide a lever for the surgeon to manipulate the plate on the bone.
    The pilot hole is made with a 1.5 mm drill.

    The green screws on the set are threaded all the way including the head. This allows the screw to lock into the plate.
    Note: A star headed screwdriver is used for the locking green screws.

    The appropriately sized locking screw (green) is inserted into the previously drilled hole. I do not tighten this screw completely at this stage as this allows me the freedom to rotate the plate into its final optimal position on the bone.
    The reduction is checked and the position of the plate on the bone is confirmed.

    The proximal fixation is done with a standard cortical non-locking screw (gold colour).
    Note: a cross-headed screwdriver is used for this screw Therefore,

    A standard drill guide is used to drill the pilot hole with a 1.5 mm drill bit. The plate does provide an opportunity to use a locking screw instead. The screw size is measured and a golden cortical screw inserted and tightened. This will allow the plate to firmly appose the bone.
    Note that, in this case, the plate is being used to bridge the comminuted fragments. Hence, the choice of the screw hole is not dictated strictly by the AO principles.


    The previously inserted distal screw is now fully tightened, locking it into the plate.

    Check X-rays are taken at this stage to confirm the fracture reduction and the plate position.

    If the reduction on the radiographs is satisfactory, the fixation is completed by inserting the 2nd locking screw distally and the 2nd screw proximally. I have used a cortical screw in this instance, but a locking green screw can be used instead.

    Final X-rays confirm the reduction.

    The screw lengths are checked and the screws changed if required.

    The rotational alignment is checked to confirm that there is no scissoring of the small finger.

    After a thorough lavage, the periosteum is closed over the plate with interrupted monofilament absorbable sutures. I believe this creates a layer underneath the tendon, minimizing the risk of adhesions. It is not always possible to obtain a watertight closure because the periosteum is usually ragged over the comminuted segment. In addition, the presence of the plate stretches the periosteum, making its closure difficult.

    The EDC and EDM are approximated with monofilament absorbable sutures.

    Skin is closed with interrupted monofilament nylon sutures. A non-adherent soft dressing is applied. The fixation is stable and rigid and therefore does not require protection in a plaster splint.

    Post Operative

    The dressings are reduced in the clinic in 48-72 hours. Active mobilization exercises are commenced at this stage along with gentle passive exercises. Special emphasis is needed to mobilise the MCP joint. A splint is usually not required.
    Sutures are removed in 2 weeks. Gentle routine activities of daily living can be started as soon as comfortable. Rigorous and heavy activity is avoided.
    Radiographs are repeated at 6 weeks. Once the fracture healing is confirmed, aggressive passive exercises can be instituted. Activities of daily living can be increased at this stage. I advise patients against heavy activities for atleast 3 months until the fracture is consolidated.
    Stiffness and tendon adhesions are a significant risk of the procedure – especially at the MCP joint. This may require a tenolysis and metalwork removal if there is no progressive improvement with therapy exercises. This secondary procedure should be delayed for atleast 3 months from the initial surgery to allow the bone to heal and consolidate.

    Recommended Reading

    Jahss SA: Fractures of the metacarpals: a new method of reduction and immobilization, J Bone Joint Surg Am 20:178-186, 1938. A classic original paper outlining the technique of fracture reduction that is still followed nearly 100 years later.
    Wolfe, SW, Hotchkiss, RN, Pederson, WC. Metacarpal neck fracture. Green’s Oper Hand Surg. 6th edition, 2011; 241. A good overview and review of this injury along with a discussion of management including K-wire fixation. However, osteosynthesis with plates and screws is not well discussed or explained.
    Poolman RW, Goslings JC, Lee J, Statius Muller M, Steller EP, Struijs PA. Conservative treatment for closed fifth (small finger) metacarpal neck fractures. The Cochrane Library. 2005 Jul 20. A Cochrane review which concluded that no single conservative method of treatment was superior to another, with all resulting in similar functional outcomes.
    Padegimas EM, Warrender WJ, Jones CM, Ilyas AM. Metacarpal Neck Fractures: A Review of Surgical Indications and Techniques. Archives of trauma research. 2016 Sep;5(3). An review article that outlines the surgical indications and examines the literature on techniques of osteosynthesis. The paper concludes that internal fixation with plates and screws is the most stable biomechanics construct and is especially suitable for comminuted fractures although carrying higher risks of complications.

    Tags:

    You might be interested in

    Luân Trần

    Bác sĩ khoa Chi trên - Bệnh viện Quân Y 175.

    Leave a Reply

    Your email address will not be published.

    Dark mode powered by Night Eye