TENDON INJURIES OF HAND

TENDON INJURIES OF HAND

Maj Vivek Mathew Philip

ANATOMY

FLEXOR TENDON INJURIES

EXTENSOR TENDON INJURIES

SPECIAL CONDITIONS

INTRODUCTION

Anatomical position

INTRODUCTIONDefinition:

Tendon injuries are common

Exact incidence is unknown

Surgeons goal: Expeditious return to full function

CARPAL TUNNEL

FDP and FDS tendons have fibrous sheaths on the palmar aspect of the digits Extent:ant to MCPJ to the distal phalanges; Fibrous arches and cruciate (cross-shaped) ligaments, which are attached posteriorly to the margins of the phalanges and to the palmar ligamentshold 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.

EXTENSOR HOODS

ED and EPL tendons expand over the proximal phalanges to form complex 'extensor hoods' or 'dorsal digital expansions' .EDM,EIP and EPB endons join these hoods. triangular in shape, with: the apex attached to the distal phalanx; the central region attached to the middle phalanx base wrapped around the sides of the MCPJ and corners attach mainly to the deep transverse metacarpal ligaments

EXTENSOR HOODS

The lumbrical, interossei, and abductor digiti minimi muscles attach to the extensor hoods.

In the thumb, the adductor pollicis and abductor pollicis brevis muscles insert into and anchor the extensor hood.

FUNCTION OF DDE

INTEROSSEI

BLOOD SUPPLY

BASIC PRINCIPLES (Sterling Bunnell)

Exact knowledge of pertinent anatomy and physiology

Sound clinical judgment

Strict atraumatic surgical technique

No Mans Land Area within digital flexor sheath, advised not to repair tendon injuries in this zone

DILEMMADespite modern advances, good results after flexor tendon repair are not uniformly obtained.

Should both tendons be repaired or just the FDP?

Should the sheath be excised or repaired?

What type of sutures should be utilized?

What type of postoperative motion most beneficial?

ANATOMYThe tendons of the nine digital flexors enter the proximal aspect of the carpal tunnel in a fairly constant relationship. The most superficial tendons are the FDS tendons to the long and ring fingers. Immediately beneath them are the FDS tendons to the index and little fingers. In the deepest layer are four tendons of the FDP and the FPL.

AnatomyFlexor tendon system consists of intrinsic and extrinsic componentsExtrinsics:FDP: flexing the DIP jointFDS: Flexing the PIP JointFPL: Flexing the IP joint of the thumbIntrinsics:Lumbricals: Flex the MCP joints and Extend the IP joints

FDP inserts on base of distal phalanxFDS inserts on sides of middle phalanxFPL inserts on proximal portion of the distal phalanx

GOAL

Primary repair of injured flexor tendons within the digital sheath is currently accepted.

Despite Modern advances, good results following flexor tendon repair is not uniformly obtained.

Control the inevitable scar formation that interferes with the beautiful gliding mechanism within the flexor tendon system

FLEXOR TENDONS

FDP and FDS tendons fibrous sheaths on the palmar aspect of the digits Extent:ant to MCPJ to the distal phalanges; Fibrous arches and cruciate (cross-shaped) ligaments, which are attached posteriorly to the margins of the phalanges and to the palmar ligamentshold 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.

Synovial sheath is reinforced by a system of fibrous pulleys5 annular pulleys (A) and 3 Cruciform pulleys (C)A1: 8-10 mm over MCPJA2: 18-20mm over proximal phalanxA3: 2-4 mm over PIPJA4: 10-12mm over middle phalanxA5: 2-4 mm over DIPJC1, C2, C3 proximal to A3, A4, A5Allow shortening of the pulley system in flexionA2 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 INJURYZone I: Between insertion of FDP and FDSZone II: From insertion of FDS to A1 PulleyZone III: Between A1 pulley and distal limit of carpal tunnelZone IV: Within the carpal tunnelZone V: Between the entrance of Carpal tunnel and musculo-tendinous junction.Thumb zones:I: Distal to IPJII: from A1 to IPJIII: Thenar eminence

Zone VThe Flexor tendons start in the distal third of the forearm at the musculotendinous junctionThe superficialis group lies palmar to the conjoined profundus tendon group covered by loose subcutaneous tissue and skin.

Zone IVFPL and FDM enters its continuous sheath which becomes the radial and ulnar bursae.

The FDS and the FDP also enter a large sheath and lie in the carpal tunnell

Zone IIIThe Lumbrical muscles originate from the FDP just distal to the carpal canalup to the beginning of the fibroosseous canal

Zone IIThe flexor synovial sheath begins at the neck of the metacarpal.The sheath is a double-wall hallow sealed at both endsFDS is in a single layer volar to FDPEach Tendon splits that diverges and wraps around FDP

Synovium membrane of the flexor tendon consists of two layers:Visceral layer: around the structure within the sheathParietal layer: covers internal aspect of the pulley system

FIBRO-OSSEOUS SHEATH

Allows smooth gliding of the tendon

Facilitates nutrition to the tendon by synovial diffusion

Tendons are enclosed within this sheath and was defined as No Mans Land, because of the generally worse outcome associated with this repair.

CAMPERS CHIASMA

In each finger, the FDS tendon enters the A1 pulley and divides into two equal halves that rotate laterally and then dorsally. The two slips rejoin deep to the FDP tendon over the distal aspect of the proximal phalanx and the palmar plate of the PIP joint at Camper's chiasma Insert as two separate slips on the volar aspect of the middle phalanx.

Nutrition in Z2

Dual Source:VascularSynovial diffusionVascular: Segmental vessels arising from the paratenon enter the tendons and travel longitudinally between the fasicles.

Vincular SystemFlexor tendon receives blood supply within the tendon sheathEach tendon is supplied by a short Vinculum (Vinculum Breve) and a long Vinculum (Vinculum LongusVBP arises from distal transverse digital artery at DIPVBS & VLP from Central Transverse digital artery at PIPVLS arises just distal to MCP from proximal transverse digital artery

NUTRITIONIn summaryIn distal forearm and palm: Perfusion from longitudinally oriented vessels over the paratenon

Within the digital sheath: Dual source of nutrition:Synovial fluid diffusionVincular systemDiffusion is more important than perfusion

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

Intrinsic Tendon healing occurs in three phases:

InflammationActive repairRemodeling

Early tendon motion has significant role in modifying the repair response

Mobilized tendons showed progressively greater ultimate load compared with immobilized tendons

Studies confirm Wolffs law which states that the strength of a healing tendon is proportional to the controlled stress applied to it

BASIC PRINCIPLES OF REPAIRAll flexor tendon repairs should be done in the OR

Use of either general or axillary block

Use tourniquet unless contraindicated

Cleanse and debride the wound

POST OPERATIVE THERAPY

Critical part of treatment for flexor tendon repair

Early passive-motion protocols

Early Active motion

EARLY PASSIVE-MOTION PROTOCOLSDorsal blocking splint to maintain wrist and MCP in flexion and block extensionKleinert protocol uses rubber bands to maintain digital flexion while allowing active extensionExtrinsic flexors are relaxed during active extensionActive extension moves the repaired tendon without resistanceWhen the extensors are relaxed,fingers are pulled backin flexion by the rubber bands4-5 weeks active flexion8 weeks resisted flexion

Early Active MotionEarly Active motion is used with increasing frequencyThis protocol requires experienceTherapistSurgeonReliable patientStrong tendon repair

Ideal tendon repair:Easy placement of sutures in the tendonSecure suture knotsSmooth junction of tendon ends without gappingMinimal interference with vascularitystrength

TECHNIQUES

Retrieve the tendon ends through the sheath in an atraumatic manner

Maintain the integrity of the pulley system (especially A2 and A4)

Create retinacular window described by Lister for preserving the flexor sheath

TECHNIQUES

Extend the original laceration for better exposure

ZigzagMidlateral

Avoid linear scars that cross flexion crease

Milk the forearm with the wrist and MCP in flexion

Do not attempt blind retrieval more than twice

Make a separate incision if necessary

Use a pediatric feeding tube to retrieve tendon stump

Suture TechniqueSuture materialNon reactivePliableSmall caliberStrongEasy to handle

Common material: Ethibond, Nylon, proline

The strength of the tendon repair is proportional to the number of core sutures that cross the tenorrhaphy site.

6-0 proline epitendinous suture is addedtidy up the repair

Contributes to the strength of the repair

McCarthy in 1996 survey: 72% used this technique

Six Strand Technique

Tendon Sheath Repair?Role of diffusion of nutrients from synovial fluidTendon within the sheath have an intrinsic capacity for healingGelberman and woo in 1990 study on dogsReconstruction of the sheath did not significantly improve repaired tendons treated with early motion rehabilitation.

Partial Tendon Laceration

Rupture, entrapment, triggering

Partial laceration involving 60% or less are best treated by early mobilization WITHOUT tenorrhaphy

Profundus Tendon AvulsionAvulsion of FDP from its insertion by forced hyperextensionMost common in the ring fingerLeddy and Parker classificationBased on the level to which the tendon retractsStatus of the tendon vascular anatomy

Type IProfundus has retracted proximally into the palmSurgery should be done in 7-10 days before a fixed muscular contracture developsLeast common

Distal digital exposure to confirm diagnosisIn Type I, a second distal palm incision will be neededTendon is reinserted into the base of distal phalanxDistally based periosteal flap is raised distal to volar plateTendon is sutured through drill holes in the distal phalanx and button tied over the nail plate

Maintain flexion of the wrist and MCPJ in a dorsal blocking splintBegin early passive motionActive motion in 3-4 weeks

Type IIProfundus retracts to PIP

Disruption of Vinculum Breve

Nutrition is maintained by Vinculum longum

May be repaired up to 3 months

Delay may convert type II into a type I if longum subsequently ruptures

Type IIIAttached bone fragment that fractures off the volar base of distal phalanxA4 pulley prevents proximal retractionBoth Vinculae are preserved

Type III attention is turned to ORIF

COMPLICATIONS

Short term:InfectionInjury to neurovascular structures or pulley systemAbnormal scarring

Long term:AdhesionRuptureJoint contracturetriggering

ComplicationsAdhesionMost common complication despite early motion protocolsTenolysis when patients progressive gain in digital motion has plateaued, usually 3-6 months after repair

Tendon RuptureNoted by the patient at popping in the hand7-10 days postop when tensile strength is weakestMRI may help in diagnosisFlexion contractureFDP advancement more than 1 cm may lead to flexion contracture and weakened hand grip because of quadrigia effect

Flexion contractureFDP advancement more than 1 cm may lead to flexion contracture and weakened hand grip because of quadrigia effect

Quadriga effectOver advancement of the FDP - weak grasp in remaining fingers due to FDP tethering; - if one FDP is tethered, the others can not shorten; - there is loss of flexion in other digits and patient may be unable to make a full fist

Triggering and entrapmentEspecially when sheath is not repairedPost traumatic regional pain syndromesCold intoleranceRSD

LATE RECONSTRUCTION

Indications:Primary repair is not possibleSegmental lossLoss of the pulley systemCompromised woundDelayed diagnosisScarring and rupture

Consideration for flexor tendon reconstructionBoyes grading scale of flexor tendon injury provides a guideline in determining the achievable outcome after flexion tendon reconstruction

The position of the digit to be reconstructed should be considered

Ulnar ring and small digits need complete flexion to provide strong grip

Full flexion of radial digits are less important because they are used for precision pinch

Full flexion of the thumb is less important than providing a stable and sensate thumb with adequate length

Prerequisite for flexor tendon reconstructionAdequate soft tissue coverageDigital vascularityHealed fracturesPassively supple jointsReturn of sensibility

Reconstruction ModalitiesTenolysisTendon advancementTendon transferTendon grafts with or without creation of artificial tendon sheath by silicon rod implantation

AlternativesAmputationJoint fusionTenodesisCaspulodesis

Tendon graftingUsed when injury has resulted in a tendon gap

Can be carried out in one or two stages

One stageAcute trauma: segment of flexor tendon lost in a clean, vascularized wound with intact pulley

Tenolysis: when tendon is deemed inadequate to permit immediate postoperative motion

TWO STAGEDirect repair is not possible

Scarred tendon bed in which primary tendon grafting has a low chance of gliding

Reconstruction of profundus tendon when sublimis is intact and there are existing scars

Two stage techniqueCreate a supple pseudosynovial sheath by implanting a silicone rodSoft tissue coverage or pulley reconstruction is performed at the first stage8 weeks later, when psuedosynovial sheath is formed, the rod is replaced by a tendon graft

Palmaris longus and plantaris

Tendon grafts that include synovial sheathToe extensors Other donorsEDC to index,EDL to 2nd, 3rd and 4th toes, EIP /EDQ

Tendon JuncturePulvertaft weave, with two or more passes through the proximal motor tendon

Distal end may be secured in multiple ways

Tension adjustment

Proximal weave is adjusted

Wrist is extended to flex the fingers into the cascade of the hand

Overcorrect slightly because some stretching occurs after surgery

PULLEY RECONSTRUCTION

Must be done during the first stageWell-healed pulley reconstruction facilitates early mobilization and gliding of tendon graftReconstruction during the second stage increases the likelihood of pulley rupture and adhesion formationMaterial usedAutogenous grafts: PL, Plantaris, to extensors, EIP, Extensor retinaculum, fascia lata

Rehabilitation

Controlled passive motion protocol started immediately

Active motion at 3 weeks

Strengthening exercised at 6 weeks

Functional Anatomy of Extensor Tendons

Intrinsic System ulnar and median N innervatedExtensor TendonsExtrinsic Systemradial N innervated

Extrinsic ExtensorsWrist Extensors: ECRL, ECRB, ECU

Finger Extensors: EDC, EIP, EDQM

Thumb Extensors: APL, EPL, EPB

Finger ExtensorsEDC has a common muscle belly with multiple tendonsEIP & EDM lie on the ulnar side of the respective EDC tendon

93EIP & EDM allow extension of IF and LF independently of EDC.

Thumb Extensors APL inserts on the metacarpal and radially abducts itEPB 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

95

Testing the Extrinsics

Compartments at Wrist

Intrinsic ExtensorsLumbricals

Interossei: 4 dorsal, 3 volar

Vascularity & Innervation:

Volar and dorsal metacarpal vessels

Median nerve supplies radial one or 2 lumbricals

Ulnar nerve supplies ulnar 2 lumbricals

EDC tendon trifurcates into central slip & 2 lateral slipsIntrinsic extensor tendons join the lateral slips to form the lateral bandsExtensor Apparatus

Lateral Band

Lateral Band

The central slip inserting onthe base of the middlephalanx and two lateral slipsinserting to the distalphalanx.

Winslows Rhombus

Juncturae Tendinium

ANATOMICAL PATTERNS OF THE EXTENSORS TO THE FINGERS

The most common patterns single extensor indicis proprius inserting to the ulnar side of the index extensor digitorum communisa 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 smallfinger, and a double extensor digiti quinti with double insertions.,

JUNCTURAE TENDINIUMFunctional roles: spacing of ED tendons force redistribution coordinate extension MP stabilization

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

SAGITTAL BANDS

Sagittal Bands Stabilize the common extensor during digital flexion over MCPJ

Limit the excursion of the common extensor tendon during digital extension

Sagittal bands 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.

Interosseous Hood

Transverse & oblique fibers of Interosseous Hood1) EDC Tendon2) Central Slip 3) Lateral Slip 4) Intertendinous Connection5) Volar Interosseous Muscle6) Lumbrical Muscle7) Interosseuos Hood (Transverse)8) Interosseuos Hood (Oblique)9) Lateral band

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2

TriangularLigamentConnects both lateral bands over the middle phalanx

1

65423PIP Joint

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 LigamentTransverse bands:

Lateral continuation ofthe triangular ligamentextending from thelateral margin of the lateral conjoinedextensor tendon to PIPJarticular volar plate

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MechanicsExtensor apparatus produces finger extension & collaborates in finger flexion

Dynamics of ExtensionExcursion Total Wrist MP PIP DIP Index 54mm 38 15 2 0Middle 55 41 16 3 0Ring 55 39 11 3 0Little 35 20 12 2 0Thumb 58 33 7 6 8

Finger Extension Combined action of long extensor & intrinsics

HyperextensionExtension of IPJs with hyperextension of MCPJ can be possible because of the strong traction of intrinsics (lumbricals)

Linked ExtensionNormal conditions extension of MP extension of DP

Extensor zones as described by Verdan

Repair Techniques

Repair Techniques

Doyle[25] proposed the following techniques for extensor tendon repair: Zone 1 (DIP joint): Running suture incorporating skin and tendon.Zone 2 (middle phalanx): Running 5-0 stitch near cut edge of tendon, completed with basket-weave or Chinese fingertrap type of cross-stitch on the dorsal surface of the tendon .Zones 3 through 5 in fingers, and zones 2 and 3 in thumb: Modified Kessler suture of 4-0 synthetic material in the thickest portion of the tendon. A 5-0 cross-stitch tied to itself at the beginning and end is run on the dorsal surface of the tendon Zones 6 and 7: Same as for zones 3 through 5 except the cross-stitch is run around the entire circumference of the tendon, if feasible

Injuries to Specific Zones

Mallet FingerDue to disruption of terminal tendon

Caused by forced flexion, hyperextension or torsion

Can result in 20 Swan Neck Deformity

Early or late volar subluxation of DIP

Closed Rupture of Extensor Tendon with Avulsion Fracture of P3

Mallet FingerClassification - Lange & Engber

I.Extensor tendon injurya. rupture/attenuationb. lacerationII.Extensor avulsionIII.Mallet #a. transepiphyseal # of childrenb. hyperextension mallet without subluxationc. hyperextension mallet with subluxation

Hyperextension Splint A tendinous injury generally can be improved byextension splinting up to 6 months from the time of injury

Splints for Mallet

Mallet Surgery

Direct repair + K-wire Pullout wire tied over padded button + K-wire Central slip tenotomy Tenodermodesis Tendon grafting - extensor or ORL Extension block wiring (Ischiguro) Arthrodesis

Direct repair + K-wireFailure of conservative treatment

Exposure and Direct Repair of the Tendon

DIP joint pinned in extension

Pullout Wire and K pin

Zone II (P2) InjuryUsually lacerations

Result in Mallet deformity

Approximate with horizontal loop sutures

DIP pinning or splint

Post op as in Mallet

Swan-neck

Zone III Injury

Injury over PIP JointCentral slip disruption

Boutonniere deformity

Zone IV InjuryUsually partial as P1 is rounded

Not much retraction of cut ends

Repair / Splinting for 3-4 weeks or 6 wks if total laceration

Zone V InjuryExtensor lag usually minimal due to incomplete injury of sagittal band

Simple Lacerations direct repair

Extensor dislocations pathology in the proximal radial sagittal band. Classically involves MF

Closed Sagittal Band InjuriesRayan GM, Murray D J Hand Surg 1994

Treatment of Sagittal Band InjuriesConservative volar splint, cast, buddy taping for 4-6 wks. Results satisfactory when treated within 3 wks

Surgical centralization of tendon by repair or reconstruction of the radial band

Composite Tissue loss in Zone VIMeticulous debridement and Flap cover with primary / secondary extensor reconstruction

Staged reconstruction with free flaps, silicon tendon implants followed by ext grafts

Single stage primary bone + tendon graft + free flaps Dorsalis pedis tendocutaneous flap

Zone VII InjuryArea under the retinaculum with6 compartments

Problem of retraction, tendon adhesion, bowstringing due to injury to the retinaculum

Closed tendon ruptures are also seen in this zone

Closed tendon ruptures of EPL, EDC mainly reported with Colles #, Smith #, Galeazzi #, ulnar subluxn, Madelung deformity, distal ulna excision, Keinbocks

Proposed to be due to avascular necrosis of the tendon, attrition

Treated by tendon transfers (preferably EIP) or graftingZone VII Injury

Zone VIII InjuriesUsually multiple tendons are affected

Repair at the musculotendinousjunctions are difficult

Associated nerve injuries must be identified

Thumb Tendons Mallet thumb rare EPB anomalies commonplace Delayed rupture of EPL may follow fractureseg. Colles, Galleazi, Smiths, Madelungs deformityEPL repair pitfallsretraction - may require re-routing

Injury to Thumb ExtensorZone I and IIMallet injuries are rare Operative treatment is a good option esp in open lacerationsZone V VIIMCP area is designated zone V Extensor lag usually minimalProximal to zone V, EPL retracts farRepair >1mo requires rerouting EPL from Listers tubercle

Long term results60% has associated injuries

Excellent or good results in 62% (TAM 89% or 2300 ) when not associated with other injuries

45% (TAM 82% or 2120) when associated with other injuries

Distal zones (I-IV) results less favorable

Loss of flexion is the most significant complication

SummaryExtension of digits is an intricate and complex mechanism

Extensor tendon injuries are common

Loss of flexion is significant

The deformity depends on the zone of injury

SummaryZone III/IV injury has a poorer result

Associated injury to joint, bone etc results in poorer results

EPM and EAM gives better results

Thank You