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Flexor tendon reconstruction- First stage using silicone spacer

    Overview

    Learn the Flexor tendon reconstruction: First stage using silicone spacer surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Flexor tendon reconstruction: First stage using silicone spacer surgical procedure.
    There are a number of clinical scenarios where primary tendon repair is not a feasible option and some form of graft reconstruction is required. This may be performed as a single or a two stage procedure.
    Here I demonstrate the first stage of a two stage flexor tendon reconstruction.
    It was in 1963 that Basset and Carrol first described the use of silicone implants in tendon reconstruction and later Hunter (1971) described the two staged technique for flexor tendon reconstruction.
    In summary the process involves using passive silicone tendon implants at the first procedure to re-establish a suitable biological environment for subsequent placement of tendon grafts.
    Readers will also find the following OrthOracle techniques of use:
    Zone 2 digital flexor tendon repair
    Flexor tendon reconstruction: Second stage.
    Reattachment of Flexor digitorum profundus (FDP) tendon using mini-mitek bone anchor.


    Indications

    INDICATIONS:
    Flexor tendons require a pristine gliding environment for optimum function. Whenever the fibro-osseous sheath is felt to be hostile to immediate placement of a tendon graft the two stage technique may be employed to restore a more suitable gliding sheath for eventual graft placement. The process depends upon a pseudosheath forming around the implant and it is the smooth inner surface of the psudosheath that will provide the smooth gliding surface required by the tendon graft.
    The two stage reconstruction technique may be employed in severe trauma, such as crush injuries, complex fractures, soft tissue destruction but also in cases of significant scarring of the flexor sheath or destruction of the pulley system.
    The Boyes pre-operative injury classification system may be used to guide reconstructive options.
    Grade 1—minimum scar, supple joints, no trophic changes
    Grade 2—scar-limiting gliding of graft
    Grade 3—joint involvement with loss of passive motion
    Grade 4—multiple digit involvement with tendon injury
    Grade 5—devastating injury with salvage procedures required.
    Grades 2-5 necessitate a two stage reconstruction over a single stage procedure.
    Sometimes the final decision about reconstructive strategy can only be made once the intra-operative dissection has been performed and therefore all possible options need to be discussed with the patient beforehand.
    In the current case 53 year old typist sustained a volar knife laceration over the PIPJ crease of the dominant small finger resulting in a complete division of FDP. She presented five weeks after the injury with a transverse scar and a lack of DIPJ flexion.
    The various management strategies were discussed with the patient and she requested exploration and attempted repair, in the knowledge that this may not be feasible at this late stage. She was therefore also consented for single stage and two stage flexor tendon reconstruction.
    SYMPTOMS & ASSESSMENT:
    The finger was held in extension with absent FDP function confirmed on passive tenodesis. There was an area of tenderness in the palm, just proximal to the A1 pulley. The patient was also getting some sensory disturbance in the small finger where the FDP stump was causing some tether around the digital nerves to the fourth webspace.
    The FDS was present but function was compromised by joint stiffness.
    INVESTIGATION:
    No further investigations were ordered. An ultrasound scan can occasionally be useful to if there is diagnostic doubt and to identify the proximal FDP stump. In Leddy-Packer type 3 FDP avulsion injuries a plain film may show an avulsed bone fragment.
    OPERATIVE ALTERNATIVES:
    It is important to have a frank discussion with the patient about the complexity of the problem and the prolonged rehabilitation time as well as the potential for an eventual outcome that may yet be compromised by stiffness, pain or a deficit in range of motion. A DIP joint arthrodesis remains a sensible alternative that must be considered.
    NON-OPERATIVE ALTERNATIVES:
    Non-operative management with an initial period of splints and activity modification should be weighed in the balance.
    CONTRAINDICATIONS:
    Patients with poor neurological or vascular function are unsuitable. Patients who have a history of poor compliance or those without the capacity to participate in a complex rehabilitation process may not be suitable candidates either. Finally patients with minimal functional demands may not benefit from a two-stage reconstruction.

    Setup

    Prior to commencing any surgery there may be an opportunity to commence a period of hand therapy aimed at improving passive range of movement and reducing swelling and softening scar tissue as much as possible.
    When planning a two stage reconstruction one must check for the presence of a palmaris longus tendon using the standard tests described elsewhere. The tendon is a useful donor but may be absent in 13% of the population.
    The procedure is carried out under regional anaesthesia or general anaesthesia. The source of tendon graft clearly has a direct bearing upon this decision.
    The hand is placed on an arm table, an upper arm tourniquet is applied and inflated. A lead hand is used to position the digits. A surgical assistant is very helpful. Bipolar cautery is used.
    A selection of silicone trials and rods should be available.

    Operation

    In the resting position the FDP deficiency in the small finger is apparent.
    The incisions have been marked out. These will be Brunners style incisons across the volar surface of the digit. One may incorporate any previous incisions or lacerations into the approach.
    The transverse incision shown here is through the original injury and this will be extended distally.

    The hand is placed into the lead hand and a volar approach to the flexor sheath is performed.
    In this case I expected to find an empty sheath distal to the FDS insertion.
    The proximal incision is marked out at the distal palmar crease where the FDP stump is expected to be. In this relatively simple case there may be normal sheath proximally and therefore a more proximal incision ought not to be required.

    Full thickness flaps are created and retracted.
    The neurovascular bundles are identified and protected.The flexor sheath is identified and examined.

    Stay sutures are used here to aid retraction.
    One can see an intact FDS insertion proximally and an empty sheath beyond this. There is some scarring present but the pulleys appear to be intact. It is important to preserve pulleys as much as possible, even when scarring is more extensive. As a minimum the A2 and A4 pulleys should be preserved. They require reconstruction if not intact
    Any scar and remaining flexor tendon within the sheath must be removed. A 1cm stump of distal FDP should be preserved if present. In this case the injury was sustained in deep flexion,, sparing the FDS and dividing the FDP very distally, near its insertion point. Therefore there were only a few mm of tendon tissue present at the insertion.
    The intact FDS was left in situ.

    Attention is now turned to finding the proximal location of the avulsed FDP stump. We attempted to avoid opening up the tissues in between which should be intact due to the presence of the FDS. This is not always possible especially when scarring is more extensive.
    The FDP was found at the location of the palpable lump, close to the neurovascular bundle and adherent to the FDS, just proximal to the A1 pulley.

    The FDP was freed from surrounding adhesions. In a finger tip to palm reconstruction, the FDP is trimmed back to healthy tendon, preserving the lumbrical origin.
    In a more severely scarred scenario, the lumbrical itself may have to be sacrificed.

    Further excision of adhesions and granulation tissue around the intact sheath.
    The A2 pulley shown here is well preserved and the sheath proximally is cleared of any adhesions.

    A set of trial spacers is seen here. These are used to determine the appropriate size for the final implant.
    In a man this may be as large as 6mm.
    The correct sized implant is one that can glide through the sheath without restriction.

    The final size chosen is the blue, 4mm implant.
    This is threaded into the pulley system using a tendon retriever, from proximal to distal taking care to ensure that the correct pathway through the FDS chiasm is followed.

    Gliding under the pulley system can be checked using the trial spacer.

    The actual implant used consists of a polyester core surrounded by a a silicone elastomer shell.
    It should be handled carefully, with non-toothed forceps, as its surface is prone to scratching.

    A 4mm silicone spacer is now unwrapped and sutured to the spacer in order that it may be pulled through into position.
    Great care is taken to minimise handling of the section that will come to lie within the sheath to avoid any surface damage.

    The spacer is passed under the pulleys and free gliding confirmed.

    The distal sheath required further scar release to enable the spacer to pass through it.
    The A4 pulley has been preserved.
    If an FDP stump is available, the spacer is sutured deep to the stump with a double mattress, 3/0 prolene suture.

    As minimal stump is available here the spacer is secured by suturing it to any remaining tendon tissue and into the periosteum beneath.
    It is important to get a central bite through the core of the spacer as peripheral sutures may cut through the silicone.

    In this finger to palm reconstruction, the silicone spacer will occupy the sheath within the digit distal to the proximal A1 pulley level. Excess spacer length is trimmed away with a sharp blade.
    The spacer is not secured proximally to allow pistoning.

    The proximal end of the spacer is now relocated within the sheath.
    Passive flexion and extension of the finger should allow gliding of the implant without buckling or bowstringing.

    The tourniquet may be released at this stage if there are concerns about bleeding.
    After irrigation and haemostasis, the wounds are closed with 5/0 nylon interrupted skin sutures.

    A non-adherent dressing is applied.

    Gauze, wool and crepe dressings are applied. Passive motion is permitted and encouraged from the outset.

    Post Operative

    The patient is allowed to return home with oral analgesia on the same day, with elevation in a Bradford sling.
    The wound is checked in clinic in 5 -7 days and passive motion commenced under the guidance of a hand therapist. This should ensure that the digit remains without contracture whilst the pseudosheath forms.
    The pseudosheath will take about 3 months to mature, and the second stage can then be embarked upon.

    Recommended Reading

    In the following study from 2002, Coyle et al looked at their results of 35 two staged flexor tendon reconstructions using the the finger to palm technique described here. They report 69% good to excellent results.
    Poor prognostic factors that were highlighted included, a delay of more than 1 year since injury, or more than 6 months between stage 1 and 2. A higher injury severity also correlated with poorer outcomes.
    J Hand Surg Am. 2002 Jul;27(4):581-5.
    Wehbe et al reported results in 150 fingers in 136 patients. Results reached a plateau at three months following grafting and a flexion contracture was the commonest complication. There was a 14% rupture rate.
    J Bone Joint Surg Am. 1986 Jun;68(5):752-63.
    Wehbe et al reported results in 150 fingers in 136 patients. Results reached a plateau at three months following grafting and a flexion contracture was the commonest complication. There was a 14% rupture rate.

    Reference

    • orthoracle.com

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