2. Anatomy
The basic structure of the extensor tendon mechanism was illustrated by
Albinus in 1734.
The extensor mechanism consists of:
• Extrinsic muscles, located on the forearm and dorsum of hand
• Intrinsic muscles, located at the level of the metacarpals and
• Fibrous structures
3.
4.
5. Dorsum of the hand
Extensor digitorum communis (EDC) tendons
are interconnected by the juncturae tendinum.
• Facilitate combined extension of the fingers.
• Lacerations proximal to the juncturae may be
masked
• At proximal phalanges, the extensor tendons
split up into three and merge with the intrinsic
extensor system to form the complex extensor
apparatus of the digits.
• Parts: the central band and two lateral bands.
6. • The extrinsic extensor tendons have three
insertion sites on the phalanges.
• Proximally, the tendon is fixed at the level of
the metacarpal heads to the palmar plate by
the sagittal bands- prevents hyperextension.
• The most important insertion is located at the
base of the middle phalanx.
• Distally, the terminal tendon is attached to the
distal phalanx.
7. Intrinsic muscles
Seven interosseous and four lumbrical
muscles
Four dorsal interosseous - originate with two
heads each from the adjacent sides of
metacarpal bones.
• First two interosseous – 2nd and 3rd finger
from the radial side.
• Third and fourth- 3rd and 4rth finger from the
ulnar side.
• Insert at the proximal phalanges and the
interosseous hood of the extensor apparatus
before joining the lateral bands
8. • Three palmar interosseous -arise from
the medial sides of the 2nd, 4rth, and
5th metacarpal bones
• Join the extensor apparatus of the
digits at the level of the proximal
phalanx after crossing palmar to the
axis of the MP joint.
9. Lumbrical muscles
• Most variable muscles of the human body
• Arise from the radial sides of the flexor
digitorum profundus tendons.
• At the level of the metacarpals.
• Join the extensor apparatus from the radial
side.
14. MECHANICS
Two set of muscles:
• INTRINSIC (originating in the hand itself & innervated by the Ulnar and Medial
nerves) and
• EXTRINSIC (originating in the forearm & innervated by the Radial nerve)
• act synergistically
• The extensor system prepares the hand for grasp & pinch by positioning the
hand in various degrees of extension.
• The most frequent activities of daily living occur in positions close to the
position of function like holding a cup or writing with a pen.
• More specialized activities like grasping a large or a very small object occur
at the extremes of extension & flexion
15. • An Extensor tendon laceration results in the decrease in the extensor force
distal to the injury.
• This force is then transferred to the joint proximal to the injury, resulting in a
net increase of extensor force at that joint,
• which causes a change in that joint position leading to characteristic
deformities
16. TENODESIS EFFECT
• Concept of movement at one joint transmitting power to an adjacent joint
( usually distal)
• As the wrist flexes , the extensor tendons tighten
• the flexor tendons relax,
• both actions serve to produce extension of the MP joints.
• The intrinsic tendons tighten with MP extension, augmenting PIP extension
• The lateral bands & the ORL are lax with PIP flexion and tighten with PIP
extension.
• The Tenodesis effect of the ORL can be demonstrated by checking passive
flexion of the DIP joint with the PIP joint in flexion and extension
17. Extensor tendon injuries
Frequently underestimated- easy access to the tendons due to:
• Thin soft-tissue envelope,
• Their extrasynovial nature, and
• Limited retraction
18. However, injuries to the extensor tendon apparatus are often more difficult to
treat due to:
• Complex interactions between the long extensor tendons and the intrinsic
muscles of the hand
• The superficial, thin structures that are very close to the underlying bones,
thus prone to develop severe adhesions
• Excursion amplitude is limited, so that even subtle lengthening or shortening
will result in severe restrictions of range of motion
• Shortcomings in adequate soft-tissue coverage will inevitably result in poor
overall results, even if the tendons themselves were addressed properly
19. DIAGNOSIS/PATIENT PRESENTATION
• Diagnosis of extensor tendon injuries is often evident
• Can be missed if the remaining tendon is strong enough to create some
extension force
• General rule, open lesions should therefore be surgically explored to identify
the extent of the injury and prevent secondary ruptures
• Function of the ED tendon should be assessed ;extension of the MP joint of
the affected digit against resistance
20. The EPB tendon inserts into the extensor
tendon apparatus of the thumb at varying
levels:
• may be able to extend the IP joint of the
thumb.
• If there is a questionable rupture of the EPL
tendon, it should therefore not be tested by
extension of the IP joint.
• Instead, the patient should be asked to lift
the thumb off the table, which will be
impossible without an intact EPL tendon.
21. • Kleinert and Verdan proposed a system to
classify lesions of the extensor tendon
apparatus into eight zones according to the level
of the lesion.
• Doyle has added a ninth zone by dividing the
forearm into the distal (zone 8) and proximal
forearm (zone 9)
22. GENERAL PRINCIPLES OF REPAIR
• The size of the extensor tendon varies considerably during its course from the
distal forearm to its terminal insertion at the distal phalanx.
• While the tendon is round and thick proximally, it becomes thin and flat more
distally.
• Suturing techniques therefore have to be adapted specifically to the location
of the injury.
• It should provide the best stability with the least shortening possible.
• Minimal changes in tendon length can cause significant alterations in range of
motion because the excursion amplitude of extensor tendons is limited.
23. • In zones II to IV, extensor tendons are thin and flat and, thus, less
amenable to suture techniques involving multiple core sutures. In
theses areas, epitendinous suture techniques have demonstrated
favourable results.
• Injuries proximal to zone 6 can be repaired in similar fashion as that for
flexor tendons because of their size (core suture plus epitendinous
suture).
• Closed ruptures of the extensor tendon at the level of the DIP and PIP
joints are often treated conservatively.
24. Zone-I injury
• Characterized by flexion at the DIP joint without active extension (mallet
finger)
• Causes include laceration and/or avulsion
• Closed injures are treated with splinting of the DIP in extension for 8 weeks
continuously, followed by night time splinting for 2 to 6 weeks.
• Open injuries :
o In most cases, skin-only laceration repair with splinting will allow healing
strong enough for extension function.
o In avulsion injuries with bone fragments > one third of the articular surface,
K-wire fixation can be used.
o Alternative options include extension block pinning
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26.
27.
28. Zone-II injury
• Characterized by inability to extend the DIP
joint
• Caused primarily by lacerations or crush
injuries
• Treatment: explore acute lacerations to rule
out tendon involvement.
• Partial lacerations (<50% tendon substance)
do not require repair.
• Complete lacerations (or partial lacerations
>50%) require suture repair.
• Avoid significant shortening of the tendon as
will result in lack of flexion at DIP joint
29. Zone-III injury
• Characterized by flexed PIP joint without active PIP
extension
• Caused by disruption of the central slip through both
closed and open injuries
• Can lead to boutonniere deformity if not properly treated
• As the lateral bands migrate volarly , they will lead to
flexion contracture of the PIP joint with hyperextension
of the DIP.
31. • Treatment options:
• Extension splinting of the PIP, K-wire fixation with the joint in extension,
tendon reinsertion with bone anchors
• In open injuries, exploration is warranted.
• Clean injuries can be repaired primarily with sutures.
• Splint for 6weeks followed by additional intermittent and night splinting for 4 to
6 weeks
32. Zone-IV injury
• Tendons becomes broader over the proximal phalanx, resulting mainly partial
lacerations.
• Tendon injuries in zone iv are often associated with proximal phalanx
fractures.
• The tendon is in close proximity to the proximal phalanx in this zone;
therefore, adhesions are relatively common and may require secondary
tenolysis.
• Treatment: Surgical repair and early active motion
33. • Partial lacerations of greater than 50% and complete tendon lacerations are
repaired with one or two modified Kessler
• 4-0 core braided polyester sutures and a 5-0 cross-stitch on the dorsal side of
the tendon.
• The core suture should be placed into the relatively thicker area of the lateral
bands toobtain maximal purchase .
34. • Dynamic splint for early motion of extensor
tendon injuries.
• Elastic traction maintains fingers in
extension.
• Excursion of the repaired extensor tendon is
achieved by active flexion.
• Splinting is started 3 to 5 days after surgery
and is maintained for
• 5 weeks. Active flexion is performed 10 times
an hour
35. Zone-V Injury
• At this level, the extensor mechanism includes the tendon and the sagittal
bands.
• The tendon is relatively broad, so complete lacerations are uncommon.
• Commonly caused by human bite injuries (“fight bite”)
• Treatment: surgical exploration and washout, especially if “fight bite” is
suspected
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37.
38. • If the injury occurred with a clinched fist, the tendon injury commonly occurs
proximal to the skin tear, and the proximal tendon end will be found proximal
with the hand in the open position.
• Concomitant sagittal band injuries can be treated conservatively with buddy
taping or splinting in cases with stable tendon injuries, partial lacerations, or
closed/ spontaneous ruptures.
• In unstable tendon injuries or old sagittal band injuries, suture repair is
recommended.
39. Zone-VI Injury
Favorable prognosis for several reasons,
• They are unlikely to be associated with a joint injury.
• There is greater tendon excursion, which means that slight limitation of motion
would not lead to the significant loss of joint motion seen with injuries over
thephalanges.
• Increased subcutaneous tissue lessens the chances of adhesion formation.
• Core sutures may be easily placed.
• Dynamic splinting can be easily performed.
40. Zone-VII Injury
• Typically involve open lacerations with multiple tendon involvement or closed
rupture associated with underlying fractures or arthritis (e.g., EPL rupture
associated with distal radius fractures or rheumatoid arthritis).
• Open lacerations at this level often require opening of the extensor
retinaculum for exposure and repair.
• Concomitant nerve injury is also common; repair if present.
• Treatment: Surgical repair with core and epitendinous sutures
• Closed ruptures of the EPL tendon often cannot be repaired primarily because
of the possibility for unacceptable tendon shortening in these cases; therefore,
primary tendon transfer (EIP to EPL) is preferred.
41. Zone VIII and IX Injury
• Often associated with injuries to the musculotendinous junctions and muscle
bellies
• Treatment: Surgical repair of tendons and/or fascial layers with brief
postoperative immobilization (3 to 4 weeks) is recommended.
• Concomitant nerve injuries must be repaired as well.
42. COMMON TYPES OF CORE SUTURE
Mattress Figure-of-eight Modified Kessler
43. • In order to achieve maximum core suture strength, locking stitches are
preferred over grasping stitches in order to prevent suture pull-out and reduce
gapping.
• However, grasping suture techniques have a higher tensile strength and less
gap formation in extensor tendon repair than mattress or figure of-eight
stitches.
44. REFERENCES :
1.Nelligan; principles of plastic surgery 4rth edition volume 6
2.Green,s Operative Hand surgery 6th edition
3.Snell,s Clinical Anatomy By Regions 10th edition
