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Internal fixation of middle phalangeal (P2) fracture using Synthes compact hand set

    Overview

    Learn the Internal fixation of middle phalangeal (P2) fracture using Synthes compact hand set 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 middle phalangeal (P2) fracture using Synthes compact hand set surgical procedure.
    Middle phalangeal (P2) fractures are increasingly common perhaps reflecting a more active population increasingly enjoying various sporting, leisure and DIY activities (though enjoying is perhaps not the best adjective to apply to DIY). It is no longer appropriate to expect patients to accept digital deformities that interfere in their social and recreational lives.
    Surgical fixation of these fractures has become popular over the last few decades. A number of factors such as better implant design, understanding of fracture biomechanics, availability of intra-operative fluoroscopy, increasing patient demands and specialist Hand Units have all revolutionised the treatment of these common hand injuries.
    The following is a step-by-step guide to internal fixation of a middle phalangeal fracture using the well-established lag screw compression technique. This procedure demonstrates the use of 1.3 mm screws from the Synthes® Compact Hand Set
    Manish Gupta
    Consultant Hand Surgeon, Queen Elizabeth Hospital ,Birmingham ,UK.
    Clinicians should seek clarification on whether any implant demonstrated is licensed for use in their own country.
    In the USA contact: fda.gov
    In the UK contact: gov.uk
    In the EU contact: ema.europa.e

    Indications

    Indications:
    A successful outcome depends on selection of the appropriate treatment, and it must be tailored to the individual patient and fracture. My indications for open reduction are:
    Open fractures
    Displaced intra-articular fractures
    Comminuted fractures
    Associated tendon or neurovascular injuries
    Fractures with difficult or failed closed reductions
    My choice of internal fixation with lag screws alone is dictated by the fracture pattern. Oblique or spiral fractures, that allow for the insertion of atleast two screws, are the most appropriate for lag screw fixation. Other less stable fracture patterns usually require fixation with plates.
    Presentations and findings:
    Middle phalangeal fractures occur following an episode of trauma. This is commonly following a twisting injury to the finger but may also involve a fall on the hand or a blunt impact on the finger. It may also be seen in patients involved in significant polytrauma.
    The patient presents with a painful, swollen and often deformed finger. The finger should be examined for any rotational or angular deformity on presentation. Associated injuries to the tendons and neurovascular structures should be identified. Definitive diagnosis is based on radiographic evaluation.
    Angular and rotational deformities are dependent on the original deforming force of the trauma. Plain radiographs in AP and lateral plane are usually sufficient to identify the fracture pattern and displacement. Displacement of the distal head fragment is best visualized on a true lateral radiograph. With lack of tendon attachment, the head fragment can displace dorsally and rotate 90 degrees. These fractures are deceptive and have little capacity to remodel. Intra-articular extension of the fracture should be identified on the radiographs.
    Alternative methods of treatment:
    Manipulation and splintage – This requires a longer period of immobilization and carries the additional risk of inadequate reduction or loss of reduction within the splint
    Closed reduction with K wire fixation – Closed reduction can be difficult in distal fractures as well as those with soft tissue interposition. Furthermore, comminuted fractures are not adequately stabilized with K wires. The risk of pintrack infections requires careful monitoring after this technique. Terndrup et al (Injury 2018) showed that burying the K wires reduces the risk of infection but requires readmission and reoperation for removal.
    Closed reduction and percutaneous screw fixation – After closed reduction (maintained with bone tenaculum), a self- tapping screw is inserted with fluoroscopic guidance through a very small incision. The value of this technique is that it minimizes soft tissue dissection and provides more stable fixation than Kirschner pins. However, the technique is quite challenging. Besides, certain fracture patterns remain unsuitable for closed reduction.

    Setup

    Informed consent is an important part of the procedure and the risks and benefits should be clearly explained to the patient. The lateral bands of the extensor tendon are in close proximity to the bone and the associated fracture. The patient should, therefore, be always counseled regarding the risk of tendon adhesions and stiffness necessitating tenolysis after the fracture is healed.
    I prefer regional anaesthesia with axillary block for this procedure. This allows for adequate upper arm tourniquet and a bloodless operating field. However, a digital block with a finger tourniquet is equally sufficient. It is important to ensure adequate anaesthesia over the dorsal aspect of the proximal interphalangeal joint by blocking the dorsal branch of the digital nerve.
    The patient is placed supine with the limb extended on an arm table. 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 midline dorsal longitudinal incision is planned overlying the proximal phalanx. The extent of the incision depends on the site of the fracture. However, extension beyond the proximal and distal interphalangeal creases is rarely required.

    The skin is incised with a No.15 blade. The subcutaneous tissue is incised with sharp dissection and the skin flaps retracted. Dorsal subcutaneous veins are cauterized along the way. The extensor tendons to the finger are exposed immediately beneath the subcutaneous tissue.
    Note the two lateral bands of the extensor tendon joined together by the intervening triangular aponeurosis. The central slip of the extensor tendon terminates just distal to the proximal interphalangeal joint at the base of the surgical incision.

    The middle phalangeal bone is approached through the interval between lateral bands. Incision is made with the blade right onto the bone, dividing the periosteum. The fracture can also be approached radial or ulnar to the conjoined lateral band.

    A combination of the surgical blade and a periosteal elevator is used to elevate the periosteum off the bone. Special care must be taken to avoid elevating the central slip at the base of the surgical approach – as this will lead to an extensor lag at the PIPJ.

    The fracture is now clearly exposed. I do not routinely wash the fracture haematoma unless I feel there is soft tissue interposition that is likely to prevent adequate reduction

    The fracture is disimpacted and reduced with longitudinal traction applied to the fingertip – as shown. The surgeon simultaneously derotates the distal fragment, thereby realigning the fragments.

    Once aligned, the reduction can be fine-tuned using a bone reduction clamp.
    Note that the clamp is partially applied in an oblique fashion with the nearside limb more proximal than the far-side limb. This will aid fine tuning of the reduction as explained next.

    The clamp is then rotated and tightened so as to lie in a transverse plane. This corrects the final displacement – reducing the fracture anatomically.
    This technique can be used in a 3-dimensional plane to correct anteroposterior malalignment as well.
    A second clamp may now be applied to allow for repositioning of the primary clamp so as to allow comfortable placement of the lag screws.

    The Synthes® 1.3 mm Compact Hand System, used in this instance, contains a variety of plate designs. (A new addition to the Synthes system is the LCP set with provision of locking plates.) The set also contains 1.0 mm screws for smaller fragments, if required. All screws come with self tapping threads.

    A 1.3 mm drill bit is used to drill the near cortex. This is the “gliding hole” which will prevent coupling of the screw to the near cortex. A drill sleeve is used to protect the soft tissues. The direction of the drill hole should be perpendicular to the fracture to allow compression at the fracture site (+/- 20 degrees) as shown by Johner et al (1983)

    A 1.0 mm drill sleeve is introduced into the gliding hole of the near cortex. This helps to better orient the direction of the remaining procedure. A 1.0 mm drill bit is now used to complete the pilot hole across the far cortex.

    The screw length is measured with the depth gauge provided. Note the direction of the hole, which is perpendicular to the fracture surface.

    A countersink is used on a manual handle onto the near cortex. This allows better fixation of the screwhead into the bone. It also prevents protrusion of the screwhead, thereby minimizing irritation of the soft tissues.

    The appropriately sized screw is inserted into the previously drilled hole and tightened. I always look for and note the compression at the fracture site as the screw is tightened.
    Note that there are options to use a smaller (1.0 mm) or larger (1.5 mm) screw depending on the size of the fragment. However, as a rule of thumb, a 1.3 mm screw is most appropriate for the middle phalanx(P2)

    The reduction is checked. Check X-rays can be taken at this stage to confirm the fracture reduction and the screw length.

    If the reduction on examination and the radiographs is satisfactory, inserting the 2nd screw distally completes the fixation.
    Note that the second screw may not line in the same plane as the first screw. This is dictated by the perpendicular orientation of the screw to the fracture plane.
    The distance between the two screws should be equal or greater than the diameter of the screwhead. This is important to prevent splintering of the cortex between the two holes and a subsequent loss of stability.

    Final X-rays confirm the reduction. The screw lengths are checked and the screws changed if required.

    It is important to ensure that the screw-tip does not protrude far beyond the volar cortex to prevent irritation of the closely adherent flexor sheath. Flexor tendon irritation may cause adhesions and stiffness and may occasionally lead to an attrition rupture.

    The lateral bands of the extensors, along with the intervening triangular aponeurosis, are approximated with monofilament absorbable sutures.

    I find it useful to check both clinical alignment and passive range of movement at the proximal and distal interphalangeal joints at this stage before proceeding to final closure of the skin.

    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. I occasionally apply a mallet splint for intermittent use to provide rest and support.
    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.
    Tendon adhesions and stiffness remain the main complication of the procedure. An extensor lag at the PIPJ or DIPJ, which is correctible passively, signifies extensor tendon adhesions. Reduced range of active flexion as compared to passive flexion signifies flexor tendon adhesions – and may be due to incorrect screw lengths protruding out of the volar cortex. Tendon adhesions may require tenolysis, which is best delayed for 3 months so as to allow the fracture to fully consolidate.

    Recommended Reading

    Müller ME, Allgöwer M. Manual of internal fixation: techniques recommended by the AO-ASIF group. Springer Science & Business Media; 1991. Pg 32. This is an excellent manual detailing the rationale and biomechanics of internal fixation devices and techniques.
    Başar H, Başar B, Başçı O, Topkar OM, Erol B, Tetik C. Comparison of treatment of oblique and spiral metacarpal and phalangeal fractures with mini plate plus screw or screw only. Archives of orthopaedic and trauma surgery. 2015 Apr 1;135(4):499-504. A comparison of lag screws alone with plates and screws for oblique and spiral fractures. The authors conclude that lag screws alone have better functional outcome in phalangeal fractures.
    Verver D, Timmermans L, Klaassen RA, van der Vlies CH, Vos DI, Schep NW. Treatment of extra-articular proximal and middle phalangeal fractures of the hand: a systematic review. Strategies in trauma and limb reconstruction. 2017 Aug 1;12(2):63-76. The authors conclude that when an open reduction is required in an extra-articular phalangeal fracture, lag screws have better outcome than plates and screws.
    Jovanovic N, Aldlyami E, Saraj B, Seidam MF, Badawi H, Shaat A, Alawadi K, Dodakundi C. Intramedullary Percutaneous Fixation of Extra-Articular Proximal and Middle Phalanx Fractures. Techniques in hand & upper extremity surgery. 2018 Jun 1;22(2):51-6. The authors describe a novel technique using an intramedullary screw to stabilise the phalangeal fractures. However, the numbers are very small and require further study before incorporating into mainstream practice.

    Reference

    • orthoracle.com

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