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Intrinsic release of the hand for Cerebral palsy contracture

    Overview

    Learn the Intrinsic release of the hand for Cerebral palsy contracture surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Intrinsic release of the hand for Cerebral palsy contracture surgical procedure.
    Cerebral palsy is the result of a non-progressive insult to the developing brain, the manifestations of which may change with skeletal growth. There are four main clinical presentations: spastic, athetoid, ataxic and mixed. Spastic cerebral palsy may be hemiplegic, diplegic. quadriplegic or monoplegic in terms of limb involvement. Spasticity is characterised by hyper-excitability of the muscle stretch reflex. This spasticity impairs voluntary use of the limb and there is commonly poor recruitment of antagonist muscle groups. There is often temporal variation in spastic tone. The case prrsented is one of spastic cerebral palsy.
    The action of the spastic muscles on the growing skeleton may result in torsional skeletal deformity, with rapid progression at the time of maximum skeletal growth. If untreated this muscle spasticity eventually can result in myostatic shortening with postural joint deformities and eventually joint contractures.
    The management of spastic cerebral palsy involves a number of disciplines and many modalities. Physiotherapy to maintain joint and muscle range of motion, splints to preserve joint position, serial splintage to improve a joints range of motion, chemo-denervation to reduce muscle tone, surgical denervation using hyper selective motor neurectomy, myotendinous lengthening procedures, joint releases, corrective joint fusions, and tendon transfers. Different procedures may be used in the same limb as a part of multilevel surgery, or at different times depending on the severity of the spasticity and postural deformity.
    The aims of surgery are to improve the functional status of the limb or in non-functional limbs to improve posture and hygiene. The case presented has had previous surgery for a severe elbow contracture and flexion contracture of the wrist and fingers. The operations included an elbow release through a medial incision preserving the tight skin in the antecubital fossa. This also allowed selective denervation of the brachialis muscle. An FDS to FDP tendon lengthening operation with a z-lengthening of FPL. This allowed the wrist to return to a neutral alignment and opening of the clenched digits. The limb remained non-functional with tight flexion deformities of the MCP joints and adducted fingers causing hygiene issues.
    In severe intrinsic contractures that cannot be corrected after intrinsic release, MCP joint releases with or without MCP joint arthroplasties may be required.
    The case presented is courtesy of Mike Craigen MBChB, FRCS( Tr & Orth), Consultant Orthopaedic Hand and upper limb Surgeon, and Paul Malone MBChB, FRCS(Plast), Fellow in Hand and upper limb surgery.

    Indications

    INDICATIONS
    Intrinsic release in the hand can be performed for spasticity or post-traumatic contracture, most commonly after a compartment syndrome.
    Where full correction of the resultant MCP joint contracture cannot be achieved after release of the intrinsics, additional release of the joint capsule can be undertaken, and occasionally bony correction may even be required.
    The aim of the operation is to improve their hand function or at a minimum finger position. In this instance the patient has had elbow release and selective denervation of the brachialis muscle as well as an FDS to FDP transfer. He has flexion deformities of the MCP joints and has difficulty flexing and extending the fingers. The am of the operation is to straighten the MCP joints and improve the flexion of the fingers.
    In general the timing of any hand correction is after addressing any proximal elbow and wrist pathologies.
    SYMPTOMS & EXAMINATION
    Intrinsic contracture is associated with MCP joint flexion and hyperextension of the PIP and DIP joints. The fingers are adducted due to the tightness of the interossei and the geometry of the MCP joint. In extension free abduction and adduction of the digits at the MCP joint are possible. However the metacarpal head is wider on the volar surface and as the MCP drops into flexion, the coronal movement is impaired.
    Long-standing intrinsic tightness results in progressive tightening of the capsulo-ligamentous structures and full passive correction may not be achievable by intrinsic release alone.
    In moderate cases, it may still be possible to extend the MCP joint passively. However, the intrinsic tightness prevents passive flexion of the PIP joints and DIP joints. In those cases, intrinsic release alone will be sufficient.
    If full passive extension of the MCP joint and passive flexion of the PIP and DIP joints is possible, a selective neurectomy of the motor nerve ends can be performed.
    Typically patients complain of difficulty in flexing the fingers. This can be due to tightness of the extrinsic tendons(Extensor digitorum communis) or intrinsic tendons(lumbricals and interossei). The diagnosis can be made using Bunnell’s test. In this test, patient’s MCP joint is held in hyperextension and IP joints passively flexed. If it is tight on attempted passive flexion, it is intrinsic tightness. The test is repeated with MCP joint in flexion. If passive flexion of the IP joints improve it confirms intrinsic tightness. In extrinsic tightness the converse is true. The IP joint flexion is tight with MCP joint in flexion it is due to extrinsic tightness.
    A functional assessment using a DASH score can be useful to quantify patients’ overall functional limitations. As spasticity affects the whole body many of these patients have problems with activities of daily living such as dressing, eating food, and washing up.
    IMAGING AND INVESTIGATION
    Usually, no radiological imaging required. However, X-Rays may be valuable in advanced post-traumatic cases with arthritic changes. Ultrasound imaging can be used while performing diagnostic blocks of the median and ulnar nerves.
    As part of the diagnostic pathway, distal ulnar nerve and median nerve blocks may be performed. Often this is under ultrasound-guided nerve stimulation using local anaesthetic infiltration. This block temporarily paralysed the interossei and lumbrical muscles and should reveal whether passive correction of the MCP joints is possible. If it is a patient will be suitable for a selective motor neurectomy. If not, due to fixed myotendinous contractures within the intrinsic musculature of the hand an open intrinsic release is indicated.
    ALTERNATIVE OPERATIVE TREATMENT
    A selective neurectomy of the motor nerve ends supplying the intrinsic muscles can be performed in mild cases were full passive extension of the MCP joint and passive flexion of the PIP and DIP joints is possible. This decision is made after an assessment following a nerve block. The advantage of neurectomy is that it is less invasive and reduces the risk of scarring which can develop around the extensor tendons after tendon release. There are no major disadvantages to neurectomy and it does not cause nerve pain as the nerve branches divided are motor nerve branches. However as mentioned earlier it is useful only in a selected group of patients.
    NON-OPERATIVE MANAGEMENT
    Botox injection into the intrinsic muscles may be performed in mild cases where full passive correction can be achieved.
    Serial splinatage can be used to correct mild deformities and adaptive static splints can be used to minimise recurrence after Botox injection.
    CONTRAINDICATIONS
    In severe joint contractures with arthritic changes, intrinsic release is contraindicated.

    Setup

    The equipment needed for this procedure include a pneumatic tourniquet, a hand table and basic hand instrumentation. Regional anaesthesia through an axillary block is usually sufficient, however in severe axillary contractures a supraclavicular block may be needed. Antibiotics are not necessary. If soft tissue correction is likely to be inadequate and the surgeon is anticipating joint excision arthroplasties, bone instruments may be needed.

    Operation – 1

    The limb is marked and the patient consented for surgery. The regional anaesthetic block has been performed and the scars from previous surgery are visible. There is a residual elbow flexion contracture but the wrist is in a good position and the digits are extended. However the MCP joints of the index through to the small remain flexed. Even after the regional block it is not possible to correct the MCP joint contracture. This indicates intrinsic contracture, however MCP joint. contracture cannot be excluded.

    The lateral view of the hand demonstrates the flexion posture of the MCP joints and the extension posture of the interphalangeal joints.

    Attempted passive correction of the deformities demonstrates the residual MCP joint flexion due to instrinsic tightness. MCP joint contracture cannot be excluded at this stage. Surgeon should be prepared to do an MCP joint release if intrinsic release fails to straighten the MCP joint. This wound involve an incision over the MCP joint on the palmar side. The flexor tendons are retracted and the volar plate of the MCP joint is released from the base of the proximal phalanx. If this is not sufficient, the accessory collateral ligaments attached to the volar plate can be released.
    There are more severe cases where soft tissue release may not be enough to straighten the MCP joints. In these cases, an arthroplasty using silicone joints can be an option. Fusion of the MCP joints is theoretically possible but involves use of metal work and there is a small risk of non-union.

    First web space contracture is frequently associated with spastic hand deformities. However in this case, passive opening of the first web space is adequate and there is no severe contracture of flexor pollics brevis or adductor pollicis brevis. Therefore surgery can be performed on the fingers alone.

    Diagramatic representation of the extensor anatomy
    This diagram shows the anatomy of the extensor tendon over the finger.
    A: EDC
    B: Sagittal band
    C: Interosseous
    D: Lumbrical
    E: Central slip
    F: Lateral band
    The Extensor Digitorum Communis(EDC) tendon lies over the MCP joint where it is stabilised by the sagittal bands which keep it central. On the index finger the Extensor Indicis Proprius(EIP tendon) blends with the EDC and over the little finger the Extensor Digiti Minimi(EDM)blends with the EDC. Over the finger the extensor tendon splits into a central slip which is attached to the base of the middle phalanx and two lateral bands which join together to attach to the base of the distal phalanx. The intrinsic muscles(lumbricals and interossei) are attached to the lateral bands.

    Lateral view of the extensor mechanism showing the insertions on lateral bands
    A: EDC
    B: Interosseous
    C: Lumbrical
    D: Lateral band

    The limb is prepared and drapedWHO check list is performed. The site of surgery is confirmed. The tourniquet is inflated after exsanguination. The skin is prepared and draped for surgery.
    The MCP joint is extended as fully as possible and there is no passive flexion possible at the PIP joint demonstrating tightness of the lateral bands.
    The intrinsic muscles, viz. the lumbricals and interossei insert into the lateral bands enabling interphalangeal extension witnMCP flxion as a normal movement pattern in the hand. However once the intrinsic muscle become tight, the MCP joint is pulled into flexion and the lateral bands become progressively tight with loss of interphalangeal joint flexion.
    The index has both a first dorsal interosseus and a more volarly placed lumbrical inserting in the radial lateral band. On the ulnar aspect the palmar interosseus inserts.
    The middle finger has no palmar interossei, however, there is a dorsal interosseus on both radial and ulnar aspects and additionally, a volar placed lumbrical inserting on the radial side. The dorsal interosseous and the lumbrical are separated proximally at the metacarpal neck by the intermetacarpal ligament. The two tendons converge and join distally, forming the radial lateral band. Proximal exposure will need separate sectioning of both tendons. Distal excision of the lateral band may not fully release the more volarly placed lumbrical and so this should be sectioned to ensure that there is no residual flexion action at the MCPJ. The lumbrical is the main intrinsic implicated in the MCPJ flexion deformity. The interossei contribute to the IPJ extension through lateral band tightening.
    The ring finger has a radial lumbrical and palmar interosseus and an ulnar dorsal interosseus.
    The small finger has a radial lumbrical and palmar interosseus. The ADM tendon lies on the ulnar side and inserts to both to the proximal phalanx and the lateral band. The dorsal interossei abduction the fingers (“D-Ab”) and the palmar interossei adduction the fingers (“P-Ad”)

    Each of the digits and tested independently to confirm the extent of each digits restriction.

    The skin incisions are marked over the MCP joints and are approximately 3cm long.The incisions will be centred over the MCP joint allowing access to the radial and ulnar lateral band components of the extensor mechanism.

    The skin is incised and careful blunt dissection is performed to identify the cutaneous nerve branches.These are branches of the superficial radial nerve on the index and middle fingers and the branches of the ulnar nerve over the ring and little fingers. There are superficial veins in the subcutaneous plane. Bipolar cautery can be used to divide small dorsal veins.

    Skin incision is deepened using a tenotomy scissors to expose the extensor mechanism. The skin is lifted off the extensor mechanism along the length of the incision by blunt dissection.

    A Ragnall retractor can be used to retract the skin edge to enable visualisation of the lateral band.
    A: A small branch of the superficial radial nerve is visible in the radial skin flap.

    The lumbrical tendon is identified on the radial side of the MCP joint of the index finger.The narrow end of a small Ragnall retractor can be use t lift the probe can be used to lift the lumbrical tendon prior to sectioning. This prevents inadvertent injury to the neurovascular bundle which lies on the volar radial aspect of the MCPJ.
    A – The first dorsal interosseus lies dorsally and inserts to the lateral band on the radial aspect of the MCPJ to the index finger
    B- Extensor digitorum communis slip to the index finger inserts in the radial aspect of the extensor hood
    C – The Extensor Indicis Proprius inserts in the ulnar aspect of the extensor hood.

    The first dorsal interosseus tendon to the index finger is divided with a scalpel.The scalpel, A, is inserted with the cutting edge dorsal and the first dorsal interosseus is sectioned from volar to dorsal away from the neurovascular structures.

    The MCPJ will still not fully extended passively due to the intact lumbrical tendon which must be separately identified and sectioned.

    The lumbrical tendon is identified deep to the first dorsal interosseus.

    The index lumbrical is sectioned with tenotomy scissors.It is not necessary to excise a section of the lumbrical tendon as it will retract due to its origin on the FDP tendon.

    Once fully released the MCPJ is passively extended to demonstrate full correction of the MCPJ to the index finger. The IPJs may not be passively correctable to flexion at this stage due to residual tightness in the ulnar lateral band. This may need releasing and is demonstrated in the next finger dissection.

    The middle finger incision is made and the deeper structures exposed in the same way as the index finger.Access to the lumbrical is more difficult due to the adjacent index finger.

    The middle finger dorsal interosseus tendon is identified and divided with a scalpel blade.

    The lumbrical tendon of the ring finger is divided.The fingers are opened in turn with release of each radial intrinsic tendon from index through to the small finger.

    The lumbrical tendon to the small finger is identified and divided

    An Almes retractor placed in the wounds edges exposes the extensor mechanism so that the ulnar intrinsic insertion can be exposed and if necessary excised.

    The ulnar sided intrinsic insertion is exposed. The middle finger has a dorsal interosseus insertion into the lateral band at this level.
    The lateral band component of the extensor mechanism is separated from the central slip component longitudinally prior to proximal volar and dorsal distal sections of the lateral band.

    The part of the extensor mechanism that is to be excised is grasped with toothed forceps to facilitate dissection. Avoid handling the remaining tendon.
    Excision of a section of the extensor apparatus is important to prevent recurrent formation and tether in scar with recurrence of the deformity.

    Operation – 2

    The distal sectioning is completed.

    The lumbrical tendon to the middle finger has not been released and now it is dissected and sectioned with a scalpel blade. The excised ulnar lateral band is on the skin adjacent to the wound.

    Full correction of the middle finger MCPJ is now achieved.

    Full flexion of the IPJs is achieved due to the release of all the intrinsic insertions.
    There is no residual joint contraction and no further bone surgery will be necessary on this digit.

    Each of the fingers is tested in turn to ensure that the soft tissues are fully released.

    The wounds are closed with a subcuticular absorbable suture4’0 Vicryl is used to close the wounds.

    Wounds over all the fingers are closed in layers.

    A dramatic on table improvement is evident when compared to the pre-operative appearance.

    The pre-operative appearance of the hand.

    Mepitel is a silicone coated polyamide mesh with open weave to allow wound exudate to pass to overlying absorbent gauze.

    Gauze padding is applied to the web spaces.

    Wool bandaging is applied to the hand from the fingertips and up to the proximal forearm.

    A volar slab of Plaster of Paris is applied with reinforcing bars to prevent cracking due to movement of the wrist and fingers.

    The cast is completed with loose bandaging. The corrected position of the hand is splinted.

    The arm is placed in a Bradford sling and elevated to reduce swelling.

    Post Operative

    The arm is elevated and the Bradford sling is recommended until the regional block has worn off.
    The dressing are removed at one week post-operatively and the cast is replaced with a thermoplastic splint with MCPJs in extension with free flexion of the IPJs permitted. The hand is not functional and so the aim of splintage is to prevent further recurrent deformity with MCPJ contracture and finger adduction. The splint is to be worn continuously for six weeks and at night time for another six weeks.

    Recommended Reading

    Release of flexors and intrinsic muscles for finger spasticity in cerebral palsy. Matsuo T1, Matsuo A, Hajime T, Fukumoto S, Chen W, Iwamoto Y. Clin Orthop Relat Res. 2001 Mar;(384):162-8.
    This study looked at 32 deformed hands in 31 patients. All of them had cerebral palsy and were treated with release of flexor digitorum superficialis and profundus muscles and intrinsic muscles. Of these 27 hands in 26 patients were followed up. Assessments were done using modified Zancolli classification, House classification, the object handling score, and the activity of daily living score. Improvements of more than one level on an average were seen in the modified Zancolli classification and House classification. The ability to grasp, pinch, and release increased and activities of daily living were improved.
    Surgical management of spasticity of the intrinsic muscles of the long fingers in adults after cerebral palsy, 68 operated hands. Saintyves G, Genet F, Allieu Y, Judet T, Denormandie P. Chir Main. 2011 Feb;30(1):46-51.
    This study looked at 68 hands in 56 patients operated for spastic hand deformities. These patients had spasticity of the intrinsic muscles of the long fingers. The aims of the operation were hygienic, aesthetic and analgesic in 15 cases, hygienic and analgesic in 32 cases and functional in 21 cases. Four hands were treated by neurectomy of the motor branch of ulnar nerve, 54 by tenotomies of the interosseous muscles, 18 by tenotomy of the abductor digiti minimi, and six by metacarpal disinsertion of the interosseous muscles. Of the total of 67 hands operated associating surgery of the extrinsic and intrinsic flexors, 63 had good primary results with four relapses, two of which required revision.
    Surgical management of the adult spastic hand. Allieu Y. Chir Main. 2011 Jun;30(3):159-75.
    This paper describes the pathology of spastic hand which is dominated by vascular hemiplegia and brain damage. The involvement of hands can be unilateral or bilateral. It involves wrist thumb and fingers. It requires multidisciplinary assessments. This repeated evaluation makes it possible to differentiate between “non functional hands”, “functional hands” and “potentially functional hands”. Surgery may involve selective neurectomies or tendon releases. Surgery can only improve the appearance of the hand, facilitate nursing or improve function.

    Reference

    • orthoracle.com

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