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Flexor tendon repair- Reattachment of Flexor digitorum profundus using mini-mitek bone anchor

    Overview

    Learn the Flexor tendon repair: Reattachment of Flexor digitorum profundus using mini-mitek bone anchor 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 repair: Reattachment of Flexor digitorum profundus using mini-mitek bone anchor surgical procedure.
    Avulsion injuries of flexor tendons injuries occur usually as part of contact sports. Flexor Digitorum Profundus of the ring finger is the most commonly effected one. These are eponymously sometimes called “Jersey finger” as often these injuries occur when the finger is caught in a player’s jersey during contact. The tendon may be avulsed cleanly from the bone or may become detached with a piece of the phalangeal bone. These injuries have been classified by Leddy and Packer into three types:
    Type 1. No bony fragment and the tendon retracts into A1 pulley area.
    Type 2: A small bony fragment and the tendon retracts into the A3 pulley area as the bone fragment is caught in the chiasma of the FDS slips
    Type 3: A large bony fragment resulting in no significant retraction as the fragment cannot pass through the sheath.
    A Type 4 has later been added which equates to a Type 3 where the bone has then detached from the tendon which retracts into the A1 pulley.
    Patients often present late after the event. The nature of an adrenaline charged contact sport means these injuries are often ignored at the time and it is only when the swelling and pain ensues that the loss of movements of the finger is noted.
    On examination there is swelling and bruising around the finger when they present early. Patients are unable to flex the DIP joint actively.
    The treatment depends on the type of injury. If the tendons has been avulsed off without a bony fragment, the finger is explored through a zig-zag incision and the tendon end retrieved. It is reattached using a variety of methods. These include drilling into bone and passing a non-absorbable suture from the tendon into the bone, passing the suture across the nail and tying it over a button or a sponge, or reattaching it using a bony anchor. If there is a substantial bone fragment, it has to reattached using screws or a small plate and screws. If the bony fragment is small it can be excised and tendon reattached .
    If presenting later than two weeks the tendon may shorten especially in Type 3 injuries. If during the operation the tendon is found tight and even on stretching does not reach the distal phalanx and decision has to be made as to whether a primary tendon grafting should be considered or to do a DIP joint fusion at a later date. Undue flexion of the finger from a very tight repair can result in PIP and DIP joint contractures which may not correctable later.
    In these cases patients should be counselled about the merits and risks of tendon reconstruction. If the lack of DIP joint flexion is not a significant problem, it is better to leave it alone. If patient’s functional demands require the DIP joint to be in flexion, then a DIP joint fusion is a simpler and effective alternative to tendon reconstruction.


    Indications

    INDICATIONS
    The indication for surgery is a patient with a closed avulsion of FDP tendons which presents within two weeks of injury. Though it is possible to explore the finger after two weeks’ delay, there is a risk that the tendon may have shortened and reattachment may result in a flexion deformity. These patients should be counselled regarding the various treatment options including conservative treatment, tendon reconstruction and DIP joint fusion.
    SYMPTOMS & EXAMINATION
    Patient usually present a few days after an initial injury which could be a game of rugby or an altercation. They complain of pain and swelling of the affected finger which typically is the ring finger. On examination there is swelling, bruising and tenderness over the finger near the DIP joint. DIP joint cannot be actively flexed. This is tested by stabilising the PIP joint and asking the patient to flex the finger. This can be differentiated from a dislocation as the joint is passively mobile. PIP joint movements are present though they are often reduced. There may be tenderness around the flexor sheath and the point of tenderness often corresponds to the site of retraction of the tendon.
    IMAGING
    A plain X-Ray in AP and Lateral views should be performed. This may show an avulsion fragment. If the clinical findings and X-Rays findings are present, further imaging is not necessary. Except in Type 4 injuries the location of the fragment indicates the level of tendon retraction. If in doubt an urgent ultrasound examination is useful to make a diagnosis.
    ALTERNATIVE OPERATIVE TREATMENT
    If patient present late(after two weeks), alternative surgical treatments should be discussed in case the tendon has shortened and cannot be reattched.In Leddy Packer Type 2 and 3, the tendon does not retract much and in those cases delayed repair may still be possible after two weeks. In other cases, the alternative operations are:
    Two stage flexor tendon reconstruction. This included inserting a silicone rod in the tendon sheath and doing a tendon graft after three months. This two-stage procedure has a long rehabilitation phase and the results are less predictable.
    A fusion of the DIP joint in 30 degrees flexion. The recovery is about 6 weeks period and in manual workers help to improve their grip.
    NON-OPERATIVE MANAGEMENT
    In patients who present late, the option of non-operative treatment should be discussed. If the DIP joint does not hyper-extend, they can be managed conservatively with hand therapy exercises to improve the range of movements of the MCP and PIP joints.
    CONTRAINDICATIONS
    There are no contraindications to surgery in an acute closed rupture apart from co-morbidities affecting anesthesia.

    Setup

    Operation is performed on a hand table under loupe magnification. The plan for reattachment of the tendon has to be made in the beginning. If bone anchors are being used, the kit should be available. If drilling across the distal phalanx or tie over the nail is done, power tools are needed.
    Surgery is performed under a Regional anaesthesia(Brachial plexus block) or General anaesthesia. An upper tourniquet is applied and the hand positioned on a hand table. A single dose of intravenous antibiotic is given.

    Operation – 1

    Visual assessment of the cascade of the fingers
    The injured hand can be seen in the photograph. In the resting position the fingers have a normal cascade which is of increasing flexion from the index to little fingers. If a finger has loss of its entire flexor mechanism it remains in extension.
    In this case the injured ring finger rests in partial flexion as the flexor digitorum superficialis (FDS) tendon is intact.

    Tenodesis test should be performedA tenodesis test demonstrates the injury well.
    When the wrist is hyperextended fingers with intact FDS and FDP tendons will progressively flex. The finger with the flexor tendon injury remains extended as can be seen here. This test is useful in patients who are unconscious as well as in children who may not be compliant with examination.

    Positioning the hand for surgery using a lead hand and towels.A Lead Hand helps to keep the fingers in extension for surgery. A Huck towel under the hand is useful to minimise pressure and also to soak up any blood or wash fluid during the operation.

    Brunner incisions being marked.A Bruner incision(zig-zag incision) is used to explore the finger. The incision is marked using a surgical marker as shown.

    Brunner incisions being marked.A close up of Bruner incision is shown here.
    It is not necessary to extend these incisions up to the mid-lateral lines as some books describe. Bruner never recommended it and extension to mid-lateral lines risk injuring neurovascular bundles which are not involved in this injury.
    Another important point is that the incision is made longitudinally along the axis of the distal phalanx beyond the DIP joint. This is because the neurovascular bundles are more towards the midline beyond the DIP joint.

    Incision being made after tourniquet inflation.Tourniquet is inflated at this stage to 250mm Hg. The incision is made using a No.15 scalpel as shown.

    Raising skin flaps and avoiding the neurovascular bundles.Skin flaps are raised as shown. Skin hooks applied to the edges of the skin help to elevate the flaps. It is important to avoid damage to the neurovascular bundles during this step. Once you have seen the neurovascular bundles one should aim to make the flaps thick by dissecting down to the flexor sheaths. The dissection is best done using the knife initially. However while trying to identify the neurovascular bundles, a tenotomy scissors is recommended.

    Exploration of the flexor sheathThe flexor sheath can be seen in the photograph. The distal part of the flexor sheath is empty. Proximally there is a blood tinged area of the flexor sheath which is the site of the retracted FDP stump.

    Exploration of the flexor sheathThe skin flaps are sutured onto the side of the finger to allow better exposure to the flexor sheath.

    Retrieving the proximal stump of the tendon from the A1 pulley area.The stump of FDP has been retrieved and can be seen held with the forceps. Usually the tendon retracts further into A1 pulley area.

    Passing the FDP tendon back through the sheath using a small catheterThe tendons stump has to be passed through the flexor sheath. To do this a flexible 16 G catheter (usually used for nerve blocks) is passed across the flexor sheath.

    Passing the FDP tendon back through the sheath using a small catheterThe stump of the tendon is sutured to the catheter using 3-0 Prolene.

    Passing the FDP tendon back through the sheath using a small catheterBy gently pulling the catheter the tendon is retrieved into the sheath. Once it has gone past the sheath the proximal end of the tendon is impaled to the bone using a blue hypodermic needle.

    Preparation of the distal phalanx prior to anchor insertion.The distal phalanx is now prepared for reattachment of the tendon. In this case the plan is to use two Micro-Mitek bone anchors(Depuy Synthese). These anchors have a 3-0 braided polyester suture(Ethibond) attached to them with two needles at the end.
    Though in some cases a Mini-Mitek anchor could be used in most cases the width of the base of the distal phalanx is the same as the length of the Mini-Mitek. This can result in migration of the anchor dorsally.
    Apart from Mitek there are several other bone anchors available in the market. They all have sufficient biomechanical pull out strengths to be used for FDP reattachment.
    A Mini-Arms retractor is used to expose the distal phalanx. The periosteum over the base of the distal phalanx is scraped to create a raw area.

    Choosing the bone anchorThe package of the bone anchor described the suture which comes with the bone anchor. It is a 3-0 braided polyester suture(Ethibond) on two needles.

    Choosing the bone anchorThe package contains the bone anchor and a drill bit.
    The drill bit can be used on a hand held handle or a power tool.The drill bit is 1.3mm X 5.0 mm in size.

    Choosing the bone anchorA close up of the Micro Mitek anchor can be seen here.

    Insertion of the Micro-Mitek anchor-Drill the bone in appropriate position.As it is a small bone, I opted to use a hand held drill handle to make a hole in the distal phalanx. This comes with the implant.

    Insertion of the Micro-Mitek anchor-Push implant fully home into drilled holeThe Micro-Mitek is inserted into the hole and the anchor should click in place. It is important to remove the cover and take out the anchor sutures before taking out the applicator.

    The steps of inserting the anchor are demonstrated on a saw bone. The anchor is inserted into the hole in the distal phalanx as shown.

    Insertion of the Micro-Mitek anchor-Slide off the plastic coverThe plastic cover of the anchor has to be removed carefully to take out the sutures. The easiest method is to use a need holder and pull out the sleeve.

    Insertion of the Micro-Mitek anchor-Slide off the plastic coverThe plastic sleeve slides off as shown.

    Insertion of the Micro-Mitek anchor-Remove the suture packetThe suture packet is pulled out using the needle holder as shown.

    Insertion of the Micro-Mitek anchor-Disengage and discard the inserting guide and handpiece.Once the sutures have been taken out of the packet, the inserter can be removed.

    Insertion of the Micro-Mitek anchorThe anchor in place with the two sutures can be seen. These sutures are used to place a core suture on the end of the tendon. The same steps in the operation can be seen now.

    Operation – 2

    Insertion of the Micro-Mitek anchor-The fixation of the anchor is tested by pulling on the attached sutures.The anchor is now inserted into the bone and the ends of the sutures can be seen.

    The anchored suture is sewn into the tendon.Using one of the needles, a two strand Kessler suture is placed on one half of the tendon.

    Insertion of a second Micro-Mitek anchorA second hole is drilled adjacent to the first one as shown. The holes can be parallel to each other or if the width of the distal phalanx is less, one above the other.

    Insertion of a second Micro-Mitek anchorA second Micro-Mitek anchor is inserted.

    A second Kessler suture is sewn into the tendonA second Kessler suture is placed on the other half of the tendon making it a four strand repair.

    Both Kessler sutures are now tightened onto the bone and tied under appropriate tension.The anchors on the distal phalanx(A) and the configuration of the core sutures(B) can be seen. As can be seen here the sutures have been offset to avoid catching on each other.

    Both Kessler sutures are now tightened onto the bone and tied under appropriate tension.The completed repair can be seen with the tendon end reattached to the distal phalanx.

    Wound closure is performedThe skin flaps are repositioned and the wound closed.

    Wound closure is performedInterrupted 5-0 Nylon sutures are used for closure.

    Wound closure is performedThe closed wound can be seen.

    Dressing are appliedDressing are now applied. The first layer is jelonet.

    Dressing are appliedA layer of dressing gauze is applied next.

    Application of backslabThis is followed by velband and POP backslab.

    Application of backslabThe completed dressings and POP backslab is seen. The backslab extends from proximal forearm to tips of fingers. The wrist is kept neutral, MCP joints flexed to 45 degrees and IP joints kept straight.
    Tourniquet is released at this stage.

    Post Operative

    Patient is given a Bradford sling to elevate the hand.
    Patients is discharged the same day with oral analgesics. The hand has to be elevated for 48 hours.
    Dressing change is done in three to four days in a dedicated Flexor tendon clinic.
    Wounds are redressed with simple dressing such as Mepore.
    A thermoplastic splint is provided by the Hand Therapists and early active mobilisation commenced.
    These include a set of active and passive exercises. Patients are shown the exercises and advised to do them every hour.
    The exercises are a set of 10. These include passive mobilisation of the fingers to flex them fully. They should NOT passively straighten them. This is followed by active flexion and active extension.
    Sutures are removed in two weeks.
    Splint is worn for five weeks.
    At this stage patients start free mobilisation and differential gliding of the tendons. These are separate exercises for FDS an FDP tendons.
    Driving is not advised for 6 weeks and even after that if patients have not regained full filexion they should not drive.
    Light activities can be started at 6 weeks.
    Heavy physical activities including gym may be started after 6 months, as there is a risk of rupture of the tendon.
    Patients should be warned about the risk of a tendon rupture. The sutures may break, get pulled out from the tendon or the anchors may come loose resulting in detachment of the tendon. If this is picked up early reattachment can be done using an alternate technique such as the tie-over method.
    If a rupture is diagnosed late a decision has to be made regarding two stage reconstruction or a DIP joint fusion.
    The outcomes are usually assessed at 6 months. The total flexion of the MCP, PIP and DIP joints are measured and any extension deficit calculated.

    Recommended Reading


    Ruchelsman DE, Christoforou D, Wasserman B, Lee SK, Rettig ME.
    Avulsion injuries of the flexor digitorum profundus tendon. J Am Acad Orthop Surg. 2011 Mar;19(3):152-62.
    Avulsions of the flexor digitorum profundus tendon may involve tendon retraction into the palm and fractures of the distal phalanx. Although various repair techniques have been described, none has emerged as superior to others. Review of the literature does provide evidence-based premises for treatment: multi-strand repairs perform better, gapping may be seen with pullout suture-dorsal button repairs, and failure because of bone pullout remains a concern with suture anchor methods. Clinical prognostic factors include the extent of proximal tendon retraction, chronicity of the avulsion, and the presence and size of associated osseous fragments. Patients must be counseled appropriately regarding anticipated outcomes, the importance of postoperative rehabilitation, and potential complications. Treatment alternatives for the chronic avulsion injury remain patient-specific and include nonsurgical management, distal interphalangeal joint arthrodesis, and staged reconstruction.
    Huq S, George S, Boyce DE. The outcomes of zone 1 flexor tendon injuries treated using micro bone suture anchors.
    J Hand Surg Eur Vol. 2013 Nov;38(9):973-8.
    This article evaluates the outcome of over 4o consecutive zone 1 flexor tendon injuries treated by using micro bone anchors.
    Patients were rehabilitated using the modified Belfast Regime. The range of motion at the distal interphalangeal joint was assessed using Moiemen’s classification. Over 5o% of patients achieved excellent or good results for range of motion at the distal interphalangeal joint and approximately one quarter had a poor outcome. A total of 94% of patients returned back to work by 12 weeks. One patient sustained a tendon rupture and one developed osteomyelitis. Over 8o% of patients were satisfied with their outcomes. This is the largest clinical study on the use of bone anchors for zone 1 tendon injuries. Our study demonstrated a low rate of complications and outcomes that compare favourably with other published techniques.
    McCallister WV, Ambrose HC, Katolik LI, Trumble TE. Comparison of pullout button versus suture anchor for zone I flexor tendon repair. Hand Surg Am. 2006 Feb;31(2):246-51.
    There was no significant difference in the clinical outcome after flexor tendon repair using either suture anchors or the pullout button technique. A significant improvement was found for time to return to work for repairs using the suture anchor technique. Flexor tendon repair can be achieved using suture anchors placed in the distal phalanx, thereby avoiding the potential morbidity associated with the pullout button technique.

    Reference

    • orthoracle.com

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