This document summarizes a seminar presentation on flexor and extensor tendon injuries of the hand. It begins with an introduction to tendon anatomy and zones of injury. It then describes the specific anatomy and function of flexor and extensor tendons. Flexor tendon injuries are discussed based on their zone of injury, with details on clinical examination, repair techniques, and postoperative rehabilitation protocols. Complications and the use of tendon grafts are also summarized. The document concludes with sections on extensor tendon anatomy, testing, and associated structures like the sagittal bands.

1. 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.

2. “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

3. BLOOD SUPPLY
Pulleysof flexiours
Synovial sheathisreinforcedbyasystemof fibrouspulleys

4. 5 annular pulleys(A) and
3 Cruciformpulleys (C)
A1: 8-10 mm overMCPJ
A2: 18-20mm overproximal phalanx
A3: 2-4 mm overPIPJ
A4: 10-12mm overmiddle phalanx
A5: 2-4 mm overDIPJ
C1, C2, C3 proximal toA3, A4, A5
Allowshorteningof the pulleysysteminflexion
A2 and A4 are consideredmostimportant.Theirdisruption
leadstobowstringing,reducedmechanical efficiencyanddecreasedflexion.
Function:increase the mechanical efficiencybypreventingbowstringing
PULLEY BIOMECHANICS
ZONES OF FLEXOR TENDON INJURY
Zone I: Betweeninsertionof FDPandFDS
Zone II: Frominsertionof FDSto A1 Pulley
Zone III:BetweenA1pulleyanddistal limitof carpal tunnel
Zone IV:Withinthe carpal tunnel
Zone V: Betweenthe entrance of Carpal tunnel andmusculo-tendinousjunction.
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
Tendonsare capable of activelyparticipatinginthe repairprocessthroughIntrinsicHealing
Tendonhealingoccursinthree phases:
1. Inflammation 2. Active repair 3. Remodelling

5.  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

7. ZONE 1: ZONE OF FDP AVULSIONINJURIES
 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 classificationofzoneI flexortendon injuries
Type I: tendonretractedintopalm(fullnessinpalm)
Type II: tendontrappedinthe sheathat PIP(unable toflex PIP)
Type III:tendontrappedinA4 pully
ZONE II-NOMANS 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
 Delayedtendon repairs are succesfull evenafter several weeks of injury
ZONE IV-TRANSVERSE CARPAL LIGAMENT
Liesdeepto deeptransverse ligament. Tendoninjuriesare 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 isa normal arcade to hand withindex fingershowingleastandlittle fingershowingmax flexion If
affectedfingershowsmore extensionthanotherdigits,chance of tendoninjuriesare high

8.  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.
Timingof flexortendon repair: Primary:repairwithin24 hours(contraindicatedincase of highgrade contamination
i.e.humanbites,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 sheathrepair:
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.

9. 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.
Directrepair: if lacerationismore than1 cm fromFDP insertion
Tendonadvancement: if the lacerationislessthen1cm frominsertion
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

10. Zone 3 injuries
Lumbrical muscle belliesusuallyare notsuturedbecause thiscanincrease the tension
of these musclesandresultina“lumbrical plus”finger(paradoxical proximal
interphalangeal extensiononattemptedactive fingerflexion).
Quadriga effect
Tendonadvancementshortensthe FDP& completesthe gripbefore the normal fingers,if the tensionontendon
graft issettoo high,and limittheirflexionandthusweekgrip
Tendon Repair:
Silfverskiöld
Fish-MouthEnd-to-End Suture (Pulvertaft)
End-to-Side method

11. 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 !!

12. Complications
 Joint contracture
 Adhesions
 Rupture
 Bowstringing
 Infection
Adhesions&stiffnessrequirestenolysisin18-25% cases
Tenolysisis indicatedafter3monthsif no improvementisnoted For1-2 months extensivephysiotherapy
DONOR TENDONS FOR GRAFTING
Palmaris Longus: Tendon of choice (fulfils requirement of length, diam & availability)
Plantaris Tendon: Equally satisfactory & advantageof 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 bellywithmultipletendons
EIP & EDM lie onthe ulnarside of the respective EDCtendon
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

13. Vascularity & Innervation
 Volar and dorsal metacarpalvessels
 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’sRhombus
The central slip inserting on the baseof the middle-phalanx
and two lateral slips inserting to the distal-phalanx.

14. Lateral band:

15. 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 systemdistal 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) Central Slip
3) Lateral Slip
4) Intertendinous Connection
5) Volar Interosseous Muscle
6) Lumbrical Muscle

16. Triangular Ligament
Connectsbothlateral bandsoverthe 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

17. 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.

18. 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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