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Extensor tendon repair in zone 4 (hand)

    Overview

    Learn the Extensor tendon repair in zone 4 (hand) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Extensor tendon repair in zone 4 (hand) surgical procedure.
    Extensor tendon injuries in the hand are commonly encountered by hand surgeons and have a peak incidence in working males between 20-29 years of age. Historically static splinting of these injuries was often advocated, but with plentiful evidence that surgical repair improves outcomes an understanding of the complex anatomy of the extensor tendon system is essential for their appropriate management.
    From the perspective of extensor tendon injury and repair eight distinct zones are recognised, running from distal phalanx to the forearm. Repairing an extensor tendon injury without a good understanding of the the nuances of each individual zone of injury can result in an extensor lag, stiffness, or failure of the repair, all of which can have significant implications in a working population.
    In contrast to flexor tendon injuries, the surgical management of extensor tendon injuries is not limited by the restrictions imposed by the fibro-osseous tunnel of the flexor system.
    As with flexor tendon injuries though, the mechanism tends to be sharp lacerations for the most part. Attritional rupture secondary to degenerative and inflammatory conditions are a different category of injury whose management is not considered in this section. Least commonly avulsion type injuries can occur and may require repair also.
    Surgical repair of extensor injuries are marked by certain unique challenges such as the thin flat nature of the distal extensor tendons which require alternatives to standard core suture techniques. In this section repair of a simple partial extensor tendon injury over the proximal phalanx (zone 4) will be demonstrated. Alongside this the important considerations of other extensor zones will be discussed.
    As with all tendon injuries, the post-operative rehabilitation regime is of critical importance to ensure the best possible result is obtained.
    Readers will also find the following OrthOracle techniques of interest:
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    Flexor tendon: Zone 2 repair
    Flexor tendon reconstruction: First stage using silicone spacer
    Flexor tendon reconstruction: Second stage.
    Flexor tendon repair: Reattachment of Flexor digitorum profundus using mini-mitek bone anchor.

    Indications

    INDICATIONS
    Laceration of an extensor tendon either within the digit or more proximally, involving at least 50% of the tendon width (see below). Lacerations of under 50% are often repaired upon exploration according to the surgeons individual preference.
    Fractures, vascular or nerve injury with associated tendon laceration.
    SYMPTOMS & EXAMINATION
    A complete history and examination are important and the mechanism of injury needs to be carefully established. This includes any other injuries to the bones, joints or any associated sensory loss.
    All skin lacerations must be examined and may require exploration.
    Composite injuries are common in hand surgery and require a low threshold of suspicion for fractures or ligamentous injury.
    Each finger should be examined in turn looking for active extension as well as extension against resistance. The latter may result in pain or weakness in partial injuries.
    Finger extension occurs through the extrinsic extensor tendons but beyond the level of the MCP joint there is an interplay between the extrinsic and intrinsic systems.
    Careful examination reveals the level of injury and the relevant components of the extensor system that may be damaged.
    If a loss of integrity of the central slip is suspected, this can be confirmed clinically using Elson’s test which is best performed under a local anaesthetic block.
    The examiner flexes the (proximal interphalangeal joint) PIPJ 90 degrees over the edge of a table top and asks the patient to extend the PIP against resistance. During this manoeuvre the distal interphalangeal joint should remain free and supple whilst the PIPJ extends. Any hyperextension at the DIPJ suggests that the lateral bands are being recruited, calling the integrity of the central slip into doubt.
    The tenodesis test is a useful method to evaluate the integrity of the tendons. It relies upon the resting tension within the flexor and extensor tendon systems. Passive flexion and extension of the wrist will cause the digits to flex and extend in a characteristic cascade. Loss of continuity in an extensor tendon for example, will cause the affected digit to remain in a flexed position upon wrist extension when compared to a neighbouring digit.
    The extensor tendons have been categorised into zones of injury that aids in planning treatment, which varies somewhat between zones.
    Zone 1 – Over the DIPJ ( a mallet type injury) – These injuries have been described in a separate section on orthoracle and are often managed non-operatively.
    Zone 2 – Middle phalanx – These are often open lacerations.
    Zone 3 – PIPJ – Central slip injuries that if untreated results in a Boutonniere deformity
    Zone 4 – Proximal phalanx – Usually result from lacerations but are often incomplete due to the broad nature of the tendon at this level.
    Zone 5 – Metacarpo-phalangeal joint (MCPJ) – These are often fight bite type injuries with a breach into the MCPJ and consequent septic arthritis. A laceration of one of the sagittal bands can lead to extensor subluxation.
    Zone 6 – Metacarpals – Intact junctura may mask an injury at this level, but more proximal injuries can result in tendon retraction.
    Zone 7 – Under the extensor retinaculum
    Zone 8 – Distal forearm – Usually resulting from open forearm trauma but occasionally a closed rupture following a hyperextension injury of the fingers.
    The local factors in each injury should be considered when planning management.
    Non-operative treatment is commonly successfully used for closed zone 1 and 3 injuries.
    Lacerations involving zones 2, 4 and 5 are usually open and therefore managed operatively. However lacerations involving less than 50% of the tendon width may be managed without tendon repair but those greater than 50% ought to undergo surgical repair.
    Conservative management of these partial lacerations involves 3-6 weeks of immobilisation in extension followed by therapy led mobilisation.
    In practice these open injuries routinely require wound debridement and exploration and therefore undergo repair.
    Repair is performed at the earliest opportunity and ideally within a week of injury.
    Emergency surgical treatment is warranted if the vascularity to the digit is also compromised. Otherwise tendon repair can be performed within a few days of the injury. The upper limit for delayed primary repair is not clearly known. Most surgeons would attempt a primary repair up to two weeks In the digits the tendon ends are unlikely to retract but proximal to the juncturae tendinae the proximal end tends to retract and delay can then make apposition of tendon ends harder to achieve.
    Avulsion or degloving injuries of the dorsal hand may involve loss of tendon and skin. Such injuries often require more complex reconstruction.
    IMAGING
    Plain X-rays are useful to rule out associated fracture, or if a retained foreign body such as glass is suspected.
    Imaging of the tendon itself using high resolution ultrasound is not routinely required unless there is doubt about the diagnosis such as in a delayed presentation or a partial injury.
    MRI is rarely used but can give very detailed images of all components of the tendon system. However ultrasound remains superior in looking for partial injuries where the dynamic nature of the testing allows more accurate diagnosis.
    ALTERNATIVE OPERATIVE TREATMENT
    In delayed presentation with a retracted tendon or scarred bed, a tendon reconstruction may be indicated.
    CONTRAINDICATIONS
    These include local or systemic contraindications to any surgery.
    Contraindications include certain mutilating hand injuries and those with skin loss of the tendon injury as well as injuries in the presence of a grossly contaminated wound.
    Anaesthetic considerations are important. However extensor tendon repair can be carried out under regional block or local nerve block.

    Setup

    The surgery may be performed under general or regional anaesthesia.
    More recently a local field blockade with local anaesthetic infiltration with adrenaline. This so called wide-awake technique avoids the use of a tourniquet and preserves active muscle activation permitting active testing of gliding prior to closure.
    In this case a brachial plexus block and high arm tourniquet were used.
    The patient was positioned supine with the arm placed on an arm table.
    Intravenenous antibiotics were administered prior to tourniquet inflation.
    Loupe magnification was use to allow adequate visualisation of all the relevant structures.
    Biplor diathermy was used.

    Operation

    A thorough pre-scrub of the hand is performed ensuring that the skin is free from debris from the field or the dressings.
    In hand trauma the patient often arrives in the operating theatre with visible debris on the skin from the field.
    A pre-operative wash with water and chlorhexidine serves to clear the skin of any gross contamination prior to the formal surgical skin preparation.
    The procedure is as much a debridement and exploration of a wound as a tendon repair.

    The hand is examined under anaesthetic to confirm the previous examination findings and plan the approach
    This is a laceration over the dorsum of the small finger between extensor zones 4 and 5.
    Passive tenodesis of the hand suggests some remaining integrity of the extensor tendon.
    In other words passsively flexing the wrist continues to extend the small finger out of the palm as it loads the fixed length of the extensor system with more tension.
    This is often painful for the patient when tested prior to regional anaesthesia.

    The skin is prepped and the limb draped, the laceration is then inspected.
    The wound edges are examined for skin loss or contaminated and potentially non viable skin.
    Other secondary lacerations must be looked for carefully to avoid missing injured structures that may not have been suspected.
    The divided tendon may be visible in the wound, allowing incisions to be planned to facilitate adequate exposure.
    Often the injured structures are not apparent.
    A useful adjunct to planning the approach is to probe the wound with a closed pair of tenotomy scissors or similar to get an idea of the size and of the degloved area.
    It’s worth noting that the position of the digits here, and in particular the MCPJs demonstrate loss of integrity in the extensor tendon to the little finger.

    In this particular case a small secondary wound, not particularly visible on the previous images was probed to see whether
    a) it was a second site of structural injury
    or
    b) it could be usefully incorporated into the exposure.
    In this case the wound did not communicate with the main wound and did not improve exposure of the tendon in the zone of injury.

    The wound is extended at either end, at 70-90 degrees to the main wound, to allow exposure of the damaged structures outside the zone of injury.These are sufficient to extend our exposure outside of the zone of injury and to allow adequate suture placement within the extensor tendon.
    Extending proximally the other structures that may be at risk are the sagittal band and central extensor tendon over the MCPJ (zone 5) as well as distal branches of the dorsal cutaneous branch of the ulna nerve.

    The tendon laceration is exposed with blunt dissection using the tenotomy scissors so an assessment Skin hooks are used to elevate the proximal and distal skin flaps.
    The flaps are full thickness flaps. The paratenon layer over the tendon must be preserved however.
    This is a 70%, oblique division of the extensor tendon.
    As mentioned above one may elect not to repair a laceration that involves less than 50% of the tendon.
    Extensor tendon lacerations distal to the MCPJ tend to be held to length by their bony attachments and the various interconnections of the dorsal extensor system.
    More proximal injuries do tend to retract.

    The distal incision is made extending int the mid-lateral aspect of the proximal phalanxThe distal incision was marked out but its use was reserved until the full extent of the extensor tendon laceration was elucidated.
    It is clear that the divided tendon lies in zone 4 and is a transverse laceration. This distal exposure must be long enough to facilitate core suture placement along the length of the tendon.
    This midlateral line is a safe zone for this incision and sill result in an acceptable scar without contracture.
    Structures at risk at this site are the distal extensor tendon and the dorsal branch of the radial digital nerve to the little finger. This may be seen crossing from the dorsum to the midlateral line and should be looked for and protected.

    The deep surface of the tendon is lifted to assess the true depth of injury, and in particular exclude joint penetration in Zone 4 injuries.The periosteum has been breeched in line with the tendon laceration.
    The laceration does not extend to the MCPJ, something that is easily missed if not looked for.
    Fractures of the proximal phalanx are common in zone 4 injuries.
    There is no evidence of fracture here.
    The tendon is lifted just enough to see the relevant structures. If a deeper injury is suspected the deep surface will of course be exposed over a longer length but this risks more scar and adhesions and is unnecessary here.

    After deeper exploration has occurred the wound is irrigated with normal saline and non-viable skin edges excisedHere 100-150 mls is adequate as the wound is not grossly contaminated.
    The procedure should be seen as a traumatic wound debridement as well as a tendon repair.

    A 2 core modified Kessler suture will be used in this partial injury.
    This is a configuration with an initial pass into the distal tendon, 1, followed by a transverse locking pass across the tendon, 2, at about 1 cm from the cut edge, exiting again through the cut end, 3.
    The suture then enters the proximal tendon, 4, and forms the same configuration, traversing, 5, and the exiting, 6.
    The aim is to get both suture ends facing each other at the same point within the cut end, ready for tying under appropriate tension and without “bunching” of the tendon ends.

    The first core suture is placed using a 4/0 Prolene on a round bodied needleHere the first suture is passed into the slightly thicker lateral area of the distal tendon to achieve maximal purchase.
    Because the tendons are flat in shape in this zone, the standard core suture techniques described for flexor tendon repair are not used here. They may be considered in other extensor zones more proximally where the tendons are more cylindrical in shape.

    The locking pass is made in the distal limb of the tendonThe suture emerges 1cm into the distal tendon.
    A locking cross suture is then placed transversely.
    Its entry point is a 1-2mm distal to the exit point, ensuring that a small amount of tendon tissue is grasped as shown in the previous diagram.
    Direct handling of the tendon is minimised to preserve the paratenon layer as much as possible and prevent extrinsic scar formation.

    The locking pass is made and both suture ends are returned to the centre.As show in the diagram, the suture is passed proximally into the cut end.
    The following step will involve passing it into the proximal end. The entry point will be exactly opposite the exit from the distal end to avoid bunching of the tendon material.

    The suture is passed into the proximal limb of the extensor tendon.The transverse pass in the proximal tendon is being made in this image.
    This is identical to the configuration in the distal tendon as shown on the diagram.
    The monofilament prolene suture has the advantage of gliding through tendon very well and therefore allows a ‘recalibration’ of the tension at time of knot placement.
    It is however vulnerable to fracture at points of stress and so should not be handled directly by any of the instruments.
    Here I am using my hand to apply some tension to the suture material following the needle.

    After the two ends of the tendon are back in the centre and facing each other, the suture is pulled together just enough to remove all of the laxity within the construct, and to bring the tendon ends together without gapping at the repair site.At the same time too much tension will cause bunching together at the points where the locking passes are made.
    This is already starting to become visible proximally in this image.
    Releasing some of the tension helps to alleviate bunching.

    The wound is washed out.
    The repair can now be assessed for gapping or over tensioning.
    The integrity of the repair and gliding of the tendon can now be made by gently flexing and extending the digit and performing a tenodesis test at the wrist.

    The tourniquet is released and any bleeding areas are cauterised with diathermy

    The wound is closed with 5/0 vicryl rapideClosure is made with interrupted sutures.
    Vicryl rapide sutures have the benefit of falling out once the wound has healed without need for removal, but can be irritating for some patients and are not suitable for certain wounds.

    The position of the digit at rest is assessed
    Once a tendon repair is performed the digit should lie in its normal cascade position.
    Slight extension of the wrist here demonstrated flexion at the MCPJ and the little finger lines up with its neighbours.

    The wound is dressed with a non adherent Mepitel dressing

    The dressing is completed with a layer off wool, a plaster backslab and crepeA volar backslab is placed with the wirst in 30 degrees of extension, the MCPJs in mild flexion of 45 degrees and the PIPJs straight.
    The limb is placed into a Bradford sling for comfort and elevation.

    Post Operative

    The patient is usually discharged home the same day with oral analgeisa. With regional anaesthetic it is worth warning the patient of a sudden surge in pain that may occur as the anaesthetic wears off. This can usually be anticipated as the sensation starts to return and can be prevented by early oral analgesics such as cocodamol 30/500.
    The backslab and dressings are all taken down at the first post-operative clinic visit at 1 week post surgery.
    The hand therapist can then see the patient for a custom made splint and an early active motion protocol.
    At our unit the patient progresses through the following stages.
    Week 1-2 – Early active movement with hook position within the splint and place and holds in full extension
    Week 3-4 – Out of splint active motion including hook grips and wrist motion
    Week 4-6 – Full fist and weaning from splint with some regular functional use such as feeding and dressing. Ongoing splint use overnight.
    Week 6 onwards – Splint free use progressing to regular function such as opening doors.
    Week 7-8 If the patient feels safe enough acativities duch as driving may be resumed. Further strengthening continues. Occasionally further therapy is required to overcome joint stiffness or tendon adhesions.

    Recommended Reading

    Results of primary extensor tendon repair of the hand with respect to the zone of injury.
    Mehdinasab SA, Pipelzadeh MR, Sarrafan N.Arch Trauma Res. 2012 Fall;1(3):131-4.
    This group stratified their results according to the zone of injury and found that a Kessler repair was adequate and that on the whole repairs in zones 3 and 5 fared better than in zones 2 and 4
    Effects of direction of tendon lacerations on strength of tendon repairs.
    Tan J, Wang B, Xu Y, Tang JB. J Hand Surg Am. 2003 Mar;28(2):237-42.
    An interesting biomechanical study showing that the obliquity of the tendon laceration must be considered when placing the cross suture in a modified Kessler repair.
    Results of primary reparing of hand extensor tendons injuries using surgical treatment.
    Karabeg R, Arslanagic S, Jakirlic M, Dujso V, Obradovic G.
    Med Arch. 2013;67(3):192-4. doi: 10.5455/medarh.2013.67.192-194.
    Another series of results following extensor repairs demonstrating good to excellent results in 80%.

    Reference

    • orthoracle.com

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