Sri Siddhartha Medical

College Agalkote,

Tumakuru.

Department of Orthopaedics.

SUBJECT SEMINAR ON: Flexors &

extensor tendon injuries of hand.

Chairperson& Moderator: Prof, & HOD: Dr Kiran kalaiah

Presented by: Dr Yashavardhan T.M

On: 30/03/2017

Introduction. Tendon injuries are the second most common injuries of the hand and therefore an important topic in trauma and orthopaedic patients.

“A glistening structure between muscle & bone which transmit force from muscle to the bone’”

Paratenon: Loose areolar tissue encasing tendon in low mechanical stress area

Tendon sheath: a dense fibrous tissue tunnel enclosing tendon in high mechanical stress area 70% collagen (Type I) Extracellular components

Elastin

Mucopolysaccharides (enhance water-binding capability) Endotenon – around collagen bundles Epitenon – covers surface of tendon Paratenon – visceral/parietal adventitia surrounding tendons in hand.

Most injuries are open injuries to the flexor or extensor tendons, but less frequent injuries, e.g., damage to the functional system tendon sheath and pulley or dull avulsions, also need to be considered.

After clinical examination, ultrasound and magnetic resonance imaging have proved to be important diagnostic tools. Tendon injuries mostly require surgical repair, dull avulsions of the distal phalanges extensor tendon can receive conservative therapy.

Injuries of the flexor tendon sheath or single pulley injuries are treated conservatively and multiple pulley injuries receive surgical repair. In the postoperative course of flexor tendon injuries, the principle of early passive movement is important to trigger an "intrinsic" tendon healing to guarantee a good outcome.

Many substances were evaluated to see if they improved tendon healing; however, little evidence was found. Nevertheless, hyaluronic acid may improve intrinsic tendon healing.

Anatomical position

Flexors muscles: FDP and FDS tendons have fibrous sheaths on the palmar aspect of the digits

Fibrous arches and cruciate (cross-shaped) ligaments, which are attached posteriorly to the margins of the

phalanges and to the palmar ligaments hold the tendons to the bony plane and prevent the tendons from bowing

when the digits are flexed. The tendons are surrounded by a synovial sheath.

Flexor tendon system consists of intrinsic and extrinsic components

Extrinsics:

FDP: flexing the DIP joint

FDS: Flexing the PIP Joint

FPL: Flexing the IP joint of the thumb

Intrinsics:

Lumbricals: Flex the MCP joints and Extend the IP joints

FDP inserts on base of distal phalanx

FDS inserts on sides of middle phalanx

FPL inserts on proximal portion of the distal phalanx

INTEROSSEIUS

BLOOD SUPPLY

Pulleys of flexiours Synovial sheath is reinforced by a system of fibrous pulleys

5 annular pulleys (A) and 3 Cruciform pulleys (C) A1: 8-10 mm over MCPJ A2: 18-20mm over proximal phalanx A3: 2-4 mm over PIPJ A4: 10-12mm over middle phalanx A5: 2-4 mm over DIPJ C1, C2, C3 proximal to A3, A4, A5 Allow shortening of the pulley system in flexion A2 and A4 are considered most important. Their disruption leads to bowstringing, reduced mechanical efficiency and decreased flexion. Function: increase the mechanical efficiency by preventing bowstringing

PULLEY BIOMECHANICS

ZONES OF FLEXOR TENDON INJURY

Zone I: Between insertion of FDP and FDS

Zone II: From insertion of FDS to A1 Pulley

Zone III: Between A1 pulley and distal limit of carpal tunnel

Zone IV: Within the carpal tunnel

Zone V: Between the entrance of Carpal tunnel and musculo-tendinous junction.

FDS decussation at A1 pulley FDS slips rotate 180° around FDP

Slips rejoin at PIP – Camper’s Chiasma Insert on P2

Tendon nutrition

Parietal paratenon

Passive nutrition by diffusion

Vincula and bony attachments

Direct nutrition

Segmental nutrition

Vincula may prevent retraction

Vascularity dominance is deep surface of tendon

Consider with suture placement

Biomechanically superior to place suture deep TENDON HEALING

Tendons are capable of actively participating in the repair process through Intrinsic Healing

Tendon healing occurs in three phases:

1. Inflammation 2. Active repair 3. Remodelling

Early tendon motion has significant role in modifying the repair response

Mobilized tendons showed progressively greater ultimate load compared with immobilized tendons

Studies confirm “Wolff’s law” which states that the strength of a healing tendon is proportional to

the controlled stress applied to it

ETIOLOGY

sharp object direct laceration (broken glass, kitchen knives or table saws) crush injury avulsions

burns animal or human bites

suicide attempts motor vehicle accidents

ZONE 1: ZONE OF FDP AVULSION INJURIES

Region b/w middle aspects of middle phalanx to finger tips Contains only one tendon-fdp

Tendon laceration occurs close to its insertion Tendon to bone repair is required than tendon repair

Leddy classification of zone I flexor tendon injuries

Type I: tendon retracted into palm (fullness in palm)

Type II: tendon trapped in the sheath at PIP (unable to flex PIP)

Type III: tendon trapped in A4 pully

ZONE II-NO MANS LAND

From metacarpal head to middle phalanx

Called so because initial attempts for tendon repair here produced poor results

FDS and FDP within one sheath

Adhesion formation risk is amplified at campers chiasma

ZONE III-DISTAL PALMAR CREASE

B/w transverse carpal ligament and proximal margin of tendon sheath formation

Lumbricals origin here prevents profundus tendons from over acting

Delayed tendon repairs are succesfull even after several weeks of injury

ZONE IV-TRANSVERSE CARPAL LIGAMENT

Lies deep to deep transverse ligament. Tendon injuries are rare.

ZONE V LIES PROXIMAL TO TRANSVERSE CARPAL LIGAMENT

SIGNS & SYMPTOMS

Unable to bend one or more finger joints Pain when bending finger/s Open injury to hand (e.g., cut on palm side of hand, particularly in area where skin folds as fingers

bend) Mild swelling over joint closest to fingertip

Tenderness along effected finger/s on palm side of hand Lies deep to deep transverse ligament Tendon injuries are rare

EXAMINATION: INSPECTION

There is a normal arcade to hand with index finger showing least and little finger showing max flexion If affected finger shows more extension than other digits, chance of tendon injuries are high

Goals of reconstruction:

Coaptation of tendons anatomical repair

multiple strand repair to permit active range of motion rehabilitation Pully reconstruction to minimize bow-stringing

atraumatic surgical technique to minimize adhesions strict adherence to rehabilitation protocol.

Timing of flexor tendon repair: Primary: repair within 24 hours (contraindicated in case of high grade contamination

i.e. human bites, infection)

Delayed Primary: 1-10 days when the wound can be still pulled open without incision

Early Secondary: 2-4 weeks. Late Secondary : after 4 weeks

No repair if less than <25% laceration, only epitenon repair in 25-50% lacerations,

core suture plus epitenon repair when >50% laceration Dorsal blocking splint for 6-8 weeks as conservative measure

Tendon sheath repair:

Advantages:

barrier to the formation of extrinsic adhesions

quicker return of synovial nutrition better tendon-sheath biomechanics

Disadvantages:

technically difficult.

may narrow and restrict tendon gliding.

ZONE 1 REPAIR

WOUND EXTENDED PROXIMALLY AND DISTALLY PROXIMAL TENDON RETRIEVED, CORE SUTURES ARE PLACED

KEITH NEEDLES USED TO PASS THE SUTURES AROUND THE DISTAL PHALANX EXITING THROUGH NAIL PLATE DISTALLY

REMAINING DISTAL END OF TENDON SUTURED TO THE RE-ATTACHED PROXIMAL PORTION.

Direct repair: if laceration is more than 1 cm from FDP insertion

Tendon advancement: if the laceration is less then 1 cm from insertion

ZONE II REPAIRS

REPAIR BOTH TENDON LACERATIONS

TENDON SHEATH MAY BE OPENED FOR EXPOSURE BUT A2 AND A4 ARE PRESERVED AS MUCH AS POSSIBLE

FDS IS REPAIRED FIRST FOLLOWED BY FDP Try to milk the tendon with the wrist flexed Morris and Martin. single skin hook is carefully inserted into sheath, then the hook is then turned

toward the tendons and when it is secured to the tendon, withdrawal of the hook should retrieve both tendons

Sourmelis and McGrouther. a small catheter is passed into the sheath and is delivered proximally into a small wound in the palm, just proximal to the A1 pulley, the catheter is sutured to both tendons 2 cm proximal to A1 pulley, which is then pulled distally to deliver the tendons into the synovial

window ZONE III REPAIRS

If both tendons are lacerated, both are repaired, end to end with

circumferential re-enforcing sutures May affect lumbricals in addition to flexor tendons Damaged lumbrical is either repaired or excised depending on severity of injury and the location of

the laceration ZONE IV REPAIR

Lacerations of flexor tendons within the carpal canal are typically associated with partial or complete laceration of median nerve

Here median nerves should be repaired first and the tendons last. ZONE V REPAIR

In this area there may be concomitant ulnar nerve & artery damage as well as radial artery & median

nerve damage. Primary repair of the arteries is usually indicated If wound is contaminated, arteries are repaired and delayed repair of tendons and nerves is planned

Zone 3 injuries

Lumbrical muscle bellies usually are not sutured because this can increase the tension

of these muscles and result in a “lumbrical plus” finger (paradoxical proximal

interphalangeal extension on attempted active finger flexion).

Quadriga effect Tendon advancement shortens the FDP & completes the grip before the normal fingers, if the tension on tendon

graft is set too high, and limit their flexion and thus week grip

Tendon Repair:

Silfverskiöld

Fish-Mouth End-to-End Suture (Pulvertaft)

End-to-Side method

Most of them involve active motion exercises. Then the suture strength has to increase

Active Extention-Rubber Band Flexion Method: e.g. Kleinert , and Brooke-Army

Immobilization Controlled Passive Motion Methods: e.g. Duran’s protocol Strickland: Early active ROM

Kleinert Protocol

Combines dorsal extension block with rubber-band traction proximal to wrist

Originally, included a nylon loop placed through the nail, and around the nail is placed a rubber band This passively flexes fingers, & the patient actively extends within the limits of the splint

Duran protocol

At surgery, a dorsal extension-block splint is applied with the wrist at 20-30° of flexion, the MCP joints at 50-60° of flexion, and the IP joints straight

Active range of motion rehabilitation

Kleinert !!

Complications Joint contracture Adhesions

Rupture Bowstringing Infection

Adhesions & stiffness requires tenolysis in 18-25% cases

Tenolysis is indicated after 3 months if no improvement is noted For 1-2 months extensive physiotherapy

DONOR TENDONS FOR GRAFTING

Palmaris Longus: Tendon of choice (fulfils requirement of length, diam & availability)

Plantaris Tendon: Equally satisfactory & advantage of being almost twice as long, but is not

accessible. Others: FDS, EDC

Extensor Tendons 1. Extrinsic System radial N innervated 2. Intrinsic System ulnar and median N innervated

Extrinsic Extensors

Wrist Extensors: ECRL, ECRB, ECU

Finger Extensors: EDC, EIP, EDQM Thumb Extensors: APL, EPL, EPB

EDC has a common muscle belly with multiple tendons

EIP & EDM lie on the ulnar side of the respective EDC tendon

Thumb Extensors

APL inserts on the metacarpal and radially abducts it

EPB inserts on proximal phalanx and extends MCP Joint

EPL inserts on distal phalanx and extends IP Joint

Testing the Extrinsics:

APL:Palpate with thumb abduction

EPB:MP extension with IP flexion, palpate tendon

EPL:Palpate tendon with retropulsed thumb

EDC:Test with wrist in neutral-extension

Testing the Extrinsics

Vascularity & Innervation Volar and dorsal metacarpal vessels Median nerve supplies radial one or 2 lumbricals

Ulnar nerve supplies ulnar 2 lumbricals

Extensor Apparatus

EDC tendon trifurcates into central slip & 2 lateral slips

Intrinsic extensor tendons join the lateral slips to form the lateral bands

Winslow’s Rhombus

The central slip inserting on the base of the middle-phalanx

and two lateral slips inserting to the distal-phalanx.

Lateral band:

Juncturae Tendinium

Functional roles:

spacing of ED tendons force redistribution coordinate extension MP stabilization

Ring finger has least independent extension due to the orientation of the juncturae

The most common patterns single extensor indicis proprius inserting to the ulnar side of the index extensor

digitorum communis a single extensor digitorum communis to the index finger a single extensor digitorum

communis to the long finger, a double extensor digitorum communis to the ring finger, an absent extensor digitorum communis to the small finger, and a double extensor digiti quinti with double insertions.

SAGITTAL BANDS

Stabilize the common extensor during digital flexion over MCPJ

Limit the excursion of the common extensor tendon during digital extension

EDC allows extension of MP joint via insertion onto the sagittal bands

There is usually no tendinous insertion of EDC to the dorsal base of the proximal phalanx

No MP joint hyperextension: EDC extends MP, PIP, and DIP joints even in the absence of intrinsic muscle

function.

INTRINSIC PARALYSIS: “slack” develops in EDC system distal to the sagittal bands all producing a flexion

posture at PIP and DIP joints, the “claw” finger.

Transverse & oblique fibres of Interosseous Hood

1) EDC Tendon

2) Centra l Slip

3) Latera l Slip

4) Intertendinous Connection

5) Volar Interosseous Muscle

6) Lumbrical Muscle

Triangular Ligament

Connects both lateral bands over the middle phalanx.

Limits the volar and lateral shifting of the

lateral conjoined extensor tendon during digital flexion

In boutonniere deformity; elongated

In fixed swan neck deformity; retracted

Retinacular Ligament

Lateral continuation of the triangular ligament extending from the lateral margin of the lateral conjoined

extensor tendon to PIPJ articular volar plat

Extensor Tendon Injury.

Extensor apparatusExtrinsic muscles (ED, EI, EDM)

Intrinsic Muscles ( Lumbricals and Interossei)

Fixed fibrous structures.

Zone 1

Mallet finger – persistent flexon of distal phalanx

Closed: splinting 6-8 weeks

Open: suture repair, Soft tissue reconstruction

Zone II injury- Middle Phalanx Level:

Repair by interrupted suture.

Immobilization for 5-6 weeks

DIP joint in extension

PIP joint left free

Zone III injury- PIP joint level

Most complex anatomically and physiologically

Causes two deformities

Boutonniere disruption of central tendon

Closed: splinting MCP and PIP in hyperextension for 6 weeks

Open: suture repair (figure of 8 suture)

Swan Neck excessive traction of central tendon

Closed: splinting DIP & Open: suture repair

Zone IV injury- shaft of proximal phalanx level

Repair relatively easy Adhesion is the problem.

Zone V injury – MP joint level.

Closed: splinting, 45 extension at wrist and 20

flexion at MCP & Open: suture repair by 5.0 prolene

Zone VI injury- Metacarpal level

Better prognosis than in fingers

All structures, even inter-tendinous band should be repaired.

Core type suture possible. Delayed suture is possible.

Zone VII- wrist level

Extensor tendons are under dorsal retinaculum. Retinaculum should be repaired

or partially preserved. Adhesion is the problem Grasping core suture should be

used. Immobilization for 5-6 weeks.

IMMOBILIZATION

INJURIES IN ZONES PROXIMAL TO MCPs May be immobilized for 3 weeks.

Afterwards, finger may be placed in removable volar splint between exercise periods for 2 weeks

Progressive ROM after 3 weeks

If full flexion is not regained rapidly, dynamic flexion may be started after 6 weeks

INJURIES IN ZONES DISTAL TO MCPs

Require a longer period of immobilization (usually 6 weeks)

A progressive exercise program is initiated

Dynamic splinting during day and static splinting at night to maintain extension

Injury to Thumb Extensor

Zone I and II Mallet injuries are rare

Operative treatment is a good option

Zone V – VII MCP area is designated zone V

Extensor lag usually minimal

Proximal to zone V, EPL retracts far

Repair >1mo requires rerouting EPL from Listers tubercle.

REFERENCES.

1. Campbel's 0perative 0rthopaedics 13th.

2. GREENS HAND TEXTBOOK.

3. AO-ASIF MANUAL OF ORTHOPAEDICS.

4. GRAYS HUMAN ANOTOMY TEXTBOOK.

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