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Extensor tendon repair in Zone 5 of the hand

    Overview

    Learn the Extensor tendon repair in Zone 5 of the 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 5 of the hand surgical procedure.
    The dorsum of the hand is easily exposed to a variety of trauma. The extensor tendon is, therefore, vulnerable and is commonly damaged. The metacarpo-phalangeal joint lies just under the extensor tendon and may also be exposed to penetrating wounds in this area. This is a step-by-step guide of managing these common injuries.

    Indications

    Indications:
    The classification of extensor tendon injuries proposed by Kleinert and Verdan ended at zone 8 (the forearm). Doyle added a ninth zone for the muscular area of the extensor mechanism at the middle and proximal forearm. The classification is easy to recall if one remembers that the joints are odd numbered; from distal to proximal, the DIP joint is zone 1, PIP joint is zone 3, MCP joint is zone 5 and the wrist joint is zone 7.
    All penetrating or lacerating injures over the knuckles (zone 5) require exploration to identify any injuries to the underlying tendon and metacarpo-phalangeal (MCP) joint. An untreated open injury over the MCP joint is vulnerable to infection and septic arthritis.
    Presentations and findings:
    Zone 5 of the extensor tendons lies over the MCP joints (Verdan). The extensor digitorum communis forms the extensor hood over the dorsum of the MCP joint and then proceeds onto the finger as a central slip and two lateral bands, to facilitate extension at the proximal and distal interphalangeal joints. The tendon is located very superficial in the region of the knuckles and is easily exposed to any penetrating injury. This patient sustained the injury on the edge of a metallic sheet, resulting in the depicted lacerations. Another common mechanism is a punching injury.
    The patient presents with an obvious laceration over the dorsum of the knuckle. As the tendon lies immediately below the skin, it may be easily visible and reveal an obvious tear. The finger may show an extensor lag with an inability to extend actively. It is important to note that the patient may be able to weakly extend the finger with pain in the presence of a partial injury to the extensor tendon.
    The extensor tendon at this level is maintained in a central position by sagittal bands, which arise from the volar plate and intermetacarpal ligaments to insert into the extensor hood. A concomitant injury to the sagittal bands will result in a subluxation of the extensor tendon and should be identified on examination.
    The junctura tendinae are stout interconnecting bands between the extensor tendons of adjacent fingers and lie proximal to zone 5. An injury to the tendon proximal to the junctura may reveal preserved active extension due to the connection with the intact adjacent tendon. This anomaly should be borne in mind during clinical examination.
    Plain radiographs are essential to exclude any retained foreign bodies. With punching injuries (Fight bites), the radiographs will enable the identification of a fracture in the head of the metacarpal. I always request for three radiographic views of the hand– Anteroposterior, lateral and oblique.
    Alternative methods of treatment:
    With open injuries in the vicinity of the MCP joint, an exploration of the wound along with repair of any tendon lacerations is the treatment of choice. There are no alternative methods, which obviate the risk of infection and septic arthritis and allow for satisfactory healing of the tendon. A delay in presentation, with established infection and purulent discharge, may require a staged procedure – with initial washout followed by tendon repair at a later date. I prefer to withhold insertion of foreign body (in the form of suture material) until the wound is clean and devoid of infection.

    Setup

    Informed consent is an important part of the procedure and the risks and benefits should be clearly explained to the patient. The proximity of the MCP joint, with the inherent risk of infection, should be clearly described. Tendon adhesions that result in subsequent stiffness must be discussed.
    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. However, I avoid exsanguination if established infection and purulent collection is present. 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 – 1

    The hand is laid prone onto the lead hand with the fingers supported on towels.
    The wound is explored to identify the laceration in the extensor tendon. It is important at this stage to look for any breach in the underlying joint capsule. If present, the joint will require thorough irrigation before closure, so as to minimize the risk of septic arthritis.
    In delayed presentation with established infection and purulent discharge, microbiology samples should be obtained before irrigation. After thorough lavage, the wound is packed and the patient returned to the ward on empirical intravenous antibiotics. Multiple washouts at 48 hourly intervals are recommended and tendon repair is withheld until the wound is clean.

    The wound is extended to allow for better visualisation of the tendon edges.

    Note the complete (100%) division of the extensor tendon (T). Also note the partial laceration in the Sagittal Bands (SB) adjacent to the main tendon. The tendon has retained its central position.
    Excessive retraction of the proximal edge is usually prevented by the intact junctura tendinae. If retracted, the tendon edges may be pulled back into position and temporarily stabilised with a hypodermic needle. This part of the procedure was not required in the presented case.
    The distal tendon edge is always held in place due to the attachment of the intrinsic tendons, and is rarely retracted.

    T = Tendon ends
    SB = Sagital Bands
    Clean-cut lacerations do not require any extensive debridement of tendon edges. The tendon morphology in zone 5 allows for placement of core sutures. However, the tendon begins to flatten considerably beyond this zone precluding the use of core sutures in distal lacerations.
    It is well accepted that core suture strength is related to the type of suture material, the caliber of the suture, and the number of suture strands crossing the repair site. The principle is to utilize a non-absorbable suture of appropriate thickness to provide adequate strength of repair.
    The choice of suture material for the core stitch is largely surgeon dependent. Options vary from monofilament synthetic materials such as Polypropelene (Prolene), Nylon and Stainless steel, to braided synthetic materials such as Polyester (Ticron, Ethibond).
    Suture caliber may vary from 3’0 to 5’0 depending on the tendon width. Increasing suture size has been shown to increase the strength of the repair, but carries the risk of increased bulkiness that may interfere with tendon gliding.
    I prefer a Polypropelene (Prolene) suture of size 4’0.
    Core suture configurations with the greatest tensile strength are those in which there are multiple sites of tendon-suture integration. However, unlike flexor tendon repairs, there are very few studies comparing strengths of different suture configurations in extensor tendons. Modified Bunnel, Modified Kessler, MGH, Becker and Modified Krackow Thomas have all been studied with minimal difference identified.
    I prefer to use a Modified Kessler 2-strand core suture – which is being described in detail here.

    In the first step of the core suture, the tendon edge is gently supported with a pair of forceps. The core suture (4’0 Prolene) is inserted from the cut surface into the substance of the tendon. The needle is directed longitudinally to exit the tendon 1 cm proximal to the cut surface. It is important for the needle to lie well within the substance of the tendon to allow maximum suture purchase.
    Note: The core stitch can alternatively start at the distal edge.

    Note the needle edge exiting approximately 1 cm proximal to the cut tendon edge.

    Studies in flexor tendon surgery reveal 1 cm to be the optimal distance for ideal strength of suture purchase without the risk of the tendon bunching up following repair. The same principle can be applied for core sutures in extensor tendon repair.

    F = Free suture end
    It is important at this stage to clasp the free suture end in a haemostat to prevent it from puling out during the repair.
    The transverse limb of the core stitch is now placed. Pennington showed that it is crucial to place the transverse limb “superficial” to the longitudinal limb, which allows the suture to “lock” when placed under tension. This prevents the suture to pull out. Conversely, a transverse limb placed “deeper” to the longitudinal limb, will “grasp” the tendon under tension, increasing the risk of a pull-out.

    The needle traverses through the entire width of the tendon to exit on the opposite side.

    The reverse longitudinal limb of the core suture is now placed – deeper to the transverse limb. The needle point should exit at the cut surface of the tendon.

    Applying tension to the suture ends will remove any “slack” within the suture material. This step is critical especially when using a braided suture – as they do not slide well through the tendon substance. Any presence of slack will result in gaping at the repair site when the tendon is placed under tension.

    The process is now repeated in the distal tendon. The longitudinal limb is placed.

    The transverse limb traverses superficial to the longitudinal limb.

    The reverse longitudinal limb brings the needle point back to the cut surface.

    The suture ends are now tied with a knot. It is important to square the knots to prevent slippage. In-vivo and in-vitro studies have shown that the suture knot is usually the weakest point of the repair. I ensure atleast 4 individual throws to secure my knots.
    Note: Braided suture materials are known to have better knot handling and knot holding properties when compared to monofilament sutures.

    Adequate tension is an important criterion of evaluation of a completed repair. The tendon edges should closely approximate without any gaps even when the underlying joints are moved through a gentle passive range. Gelberman showed that there is a negative effect of early repair site gap formation on tendon healing and accrual of repair site strength. An in vivo canine study showed that tendons healing without repair site gaps or with gaps less than 3 mm acquire strength 6 weeks after repair. In this same study, if there was a repair site gap greater than 3 mm, significant accrual of repair site strength did not occur.
    Conversely, over-tensioning will produce bunching up of the tendon at the repair site.

    Epitendinous sutures are known to not only smoothen the repair site but to also improve the strength of the repair. However, all studies relating to epitendinous sutures are documented with flexor tendon surgery. I do not routinely use circumferential epitendinous sutures for extensor tendons. But a superficial layer of epitendinous suturing allows me to simultaneously repair the tear in the sagittal bands along with augmentation of my core stitch in the tendon.
    A simple running suture or a variety of more complex configurations may be used for epitendinous closure. I use the Silfverskiold method with a synthetic monofilament suture of Polyropelene (Prolene) of caliber 6’0 for this part of the procedure.

    The Silfverskiold epitendinous repair starts with a standard knot at one end of the suture line – the ulnar end in this case. I leave the tail long after cutting, to enable me to tie the running suture to itself after completion.

    The repair is a cross-stitch pattern with the transverse limbs on each side of the restored tendon edge running opposite (radial to ulnar) to the direction of the repair (ulnar to radial)
    Locking the suture after each pass of the needle is not crucial for this technique.

    Once the repair has reached the end on the radial side, it can be delivered through the tendon back to the ulnar side enabling you to tie it to itself.

    The wound is closed with interrupted nonabsorbable nylon sutures (of caliber 5’0). However, some surgeons prefer using a monofilament absorbable suture in a continuous subcuticular fashion to achieve skin closure.

    Nonadherent dressings are applied

    The tendon repair needs to be protected in a plaster cast in the immediate post-operative period.

    A volar slab is applied

    The fingers are maintained in attitude of neutral extension at the MCP and PIP joints. The wrist is held in an attitude of 30 degrees of dorsiflexion.

    Operation – 2
    Post Operative

    The dressings are reduced in the clinic in 48-72 hours and the plaster cast discarded. The patient is then started on an extensive and rigorous rehabilitation regimen under the watchful eyes of an Occupational Therapist. Sutures are removed in 2 weeks.
    The rehabilitation program is a modification of the Norwich regime of Early Active Motion (EAM). This requires a thermoplastic splint to protect the repair. The splint is forearm based and extends upto the fingertips. It is worn on the volar aspect of the hand continuously for 4 weeks; followed by a further 2 weeks at night. The splint supports the hand in 30 degrees of dorsiflexion at the wrist, mild (30 degrees) flexion at the MCP joints and extension at the interphalangeal joints.
    The exercises involve active and passive extension of the digits across all joints and flexion/extension of the interphalangeal joints while the MCP joints are supported in extension. Gentle composite flexion and tendon gliding exercises are started at 4 weeks. All splintage is discontinued at 6 weeks when light activities can commence. Unrestricted activity is allowed after 12 weeks.
    Oedema management and scar massage are instituted as required.
    Tendon rupture following repair is a risk that requires care and protection. Previous post-operative protocols required plaster immobilization for 4 weeks to prevent this; but resulted in significant joint stiffness. Newer repair techniques allow earlier protected mobilization. However, regular monitoring and early identification of any rupture of the repair remains essential.
    Tendon adhesions following repair and subsequent joint stiffness are other common complications. It is, therefore, important to ensure patient compliance with the mobilization exercises during rehabilitation, to minimize this risk. Resistant cases may require further surgery in the form of tenolysis and contracture release.

    Recommended Reading

    Tubiana R, Valentin P. The anatomy of the extensor apparatus of the fingers. Surgical Clinics of North America. 1964 Aug 1;44(4):897-906.
    This is a landmark document that describes the anatomy of the extensor apparatus in detail, outlining the significance of the delicate balance between the various components. The paper argues how interference and disruption of this balance can result in the commonly seen complications of extensor tendon injuries.
    Marshall TG, Sivakumar B, Smith BJ, Hile MS. Mechanics of Metacarpophalangeal Joint Extension. The Journal of hand surgery. 2018 Feb 1.
    This paper debunks the myth that the sagittal bands are the major force of extension at the MCP joint by acting as a lasso over the extensor tendon. The cadaveric study confirms the tendon to be the major vector for MCP joint extension, thereby justifying its repair, especially in zone 5.
    Collocott SJ, Kelly E, Ellis RF. Optimal early active mobilisation protocol after extensor tendon repairs in zones V and VI: A systematic review of literature. Hand therapy. 2018 Mar;23(1):3-18.
    This is a systematic review of rehabilitation following extensor tendon repairs in zone 5 of the hand. The authors accept that early mobilisation protocols have consistently better outcomes than immobilisation regimes. They suggest that relative motion protocols may allow earlier return to work when compared with controlled active motion regimes; but do not have any long term significant differences.

    Reference

    • orthoracle.com

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