This document discusses flexor tendon injuries and their treatment. It begins with an overview of flexor tendon anatomy, morphology, zones of injury, and the challenges of repair. It then describes techniques for clinical evaluation, including testing of the flexor digitorum profundus and superficialis tendons. Principles of flexor tendon repair are outlined, including approaches for zone 1 and zone 2 injuries. Core suture techniques like the Kessler and Tajima methods are explained. Post-repair management considers risks of adhesion formation and importance of early motion.

1. Sqn Ldr Deepak Kumar, Resident
Surgery
FLEXOR TENDON
INJURIES

2. Introduction
 FTI: considered one of the most challenging problems
for hand surgeons
 Suturing of a divided tendon usually results in:
 Some thickening enlarged area cannot pass the
constricting pulley and motion is prevented
 Bunnell coined the term "no man's land" to emphasize
the difficulties associated with injuries in this area of the
digital sheath

3. Introduction
 Restoration of satisfactory digital function after flexor
tendon lacerations remains one of the most challenging
problems in hand surgery
 Prior to the 1960’s tendons lacerated in “no man’s land”
were not repaired in favor of delayed grafting
 Kleinert and Verdan (1960’s) showed superior results
with primary repair leading to general acceptance of this
approach

4. Introduction
 In the past 25 years more scientifically sound research
has advanced our understanding of flexor tendon
structure, nutrition, healing, biomechanics, response to
stress, repair techniques
 Many studies have examined passive and active motion
protocols

5. Tendon Morphology
 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
 Synovial like fluid environment

6. Anatomy
 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

7. Anatomy
 Extrinsic flexors
 Superficial group
PT, FCR, FCU,
PL
Arise from medial
epicondyle, MCL,
coronoid process

8. Anatomy
 Extrinsic Flexors
 Intermediate group
 FDS
 Arises from medial
epicondyle, UCL,
coronoid process
 Usually have
independent
musculotendinous
origins

9. Anatomy
 Extrinsic flexors
 Deep group
 FPL – originates from
entire medial third of
volar radius
 FDP – originates on
proximal two thirds of
the
ulna, often has common
musculotendinous

10. Anatomy
 FDP inserts on base
of distal phalanx
 FDS inserts on sides
of middle phalanx
 FPL inserts on
proximal portion of
the distal phalanx

11. Anatomy
 Intrinsics:
 Lumbricals:
Flex the
MCP joints
and Extend
the IP joints

12. Carpal Tunnel
 The 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

13. Fibro-Osseous Sheath
 FDP and FDS tendons fibrous
sheaths on the palmar aspect of
the digits
 Extent: Ant to MCPJ to the distal
phalanges
 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

14. Fibro-Osseous Sheath
 Allows smooth gliding of the tendon
 Facilitates nutrition to the tendon by
synovialdiffusion
 Tendons are enclosed within this sheath and
was defined as “No Man’s Land”, because of
the generally worse outcome associated with
this repair

15. Camper’s 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.

16. Pulley system
 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

17. Pulley system
 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

18. Biomechanics
 Efficiency of Flexor system : degree to which tendon
excursion and muscle contraction translates into joint
motion
 Governed by the integrity of pulley system and resistence
to glide
 Pulley decreases the arm length at each joint leading to
motion
 A2 and A4 are considered most important. Their disruption
leads to bowstringing, reduced mechanical efficiency and
decreased flexion

19. Tendon Nutrition
 Vascular
 Longitudinal vessels
 Enter in palm
 Enter at proximal synovial fold
 Segmental branches from digital arteries
 Long and short vinculae
 Vessels at osseous insertions
 Synovial fluid diffusion
 Imbibition (pumping mechanism)

20. Vincular System
 Flexor tendon receives
blood supply within the
tendon sheath
 Each tendon is supplied
by
 short Vinculum
(Vinculum Breve)
 long Vinculum
(Vinculum Longus)

21. Vincular System
 VBP arises from distal
transverse digital artery at
DIP
 VBS & VLP from Central
Transverse digital artery at
PIP
 VLS arises just distal to
MCP from proximal
transverse digital artery

22. 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 musculotendinous
junction
 Thumb zones:
 I: Distal to IPJ
 II: from A1 to IPJ

24. Tendon healing
 2 forms:
 Intrinsic healing : occurs without direct blood flow to
the tendons
 Extrinsic healing: occurs by proliferation of fibroblast
from peripheral epitendon; adhesions occur because
of this process and limit tendon gliding within the
synovial sheath

25. Tendon healing
 Intrinsic Tendon healing occurs in
three phases:
Inflammation
Active repair
Remodeling

26. Tendon healing
 Inflammatory phase (0-5 days)
 Epitenon proliferation within 1 cm of the repair site
 Fibronectin within the repair site: Chemotactic for
fibroblasts
 Macrophage and inflammatory cells accumulate to
debride non viable tissue
 Strength of repair in reliant on the strength of
suture itself

27. Tendon healing
 Active repair phase(5-28days):
 Epitenon fibroblasts secrete type I collagen to unite
the tendon ends
 The repair is biomechanically weakest from 10-15
days
 Remodeling phase(>28 days):
 Collagen in the repair site remodels and continues to
strenghten

28. Tendon Adhesion
 Healing that is largely based on intrinsic cellular activity
will result in fewer, less dense adhesions
 Factors influencing adhesion formation
 Traumatic injuries/reparative surgery
 Ischemia: disruption of vinculae
 Immobilization
 Gapping at repair site
 Injury/resection of flexor sheath component

29. Diagnosis of Flexor Injury
 Posture of Hand/ Normal cascade
 Passive tenodesis test
 Forearm compression test
 Independent testing of FDS & FDP
 Imaging

30. Normal Flexion Cascade

31. Principles of Evaluation:
 Full ROM of each tendon against resistance should be
assessed and compared with the uninjured side
 Important to test resistance because up to 90 % of a
tendon can be lacerated with preservation of ROM without
resistance
 Pain along the course of the tendon during resistance
testing suggests a partial laceration even if the strength
appears adequate

32. Clinical Examination
 FDP is tested by flexing the DIP against resistance
while the MP and PIP are held in extension
 FDS is tested by flexing the PIP against resistance
while the remaining fingers are held
 Sensation and ROM should be tested before
anesthesia applied

33. FDS: Clinical Exam

34. FDP: Clinical Exam

35. Imaging:
In case of closed tendon rupture:
 Ultrasonography : Not reliable in patial tears
 Computed Tomography
 MRI : Gold standard

36. Flexor Tendon Repair
TIMING
Temporally classified into
 Primary repair (within 12 hours)
 Delayed primary repair (within 10 to 14 days or
before the skin wound has healed)
 Secondary repair (2 to 4 weeks)
 Late secondary repair (after 4 weeks

37. Flexor Tendon Repair
 Best - done within hours and second best after 10 days.
worst results - done between 4 and 7 days.
 Adhesion formation and tendon gliding are adversely
affected when repairs were done after 7 days.
 Delay several days if wound infected.

38. General Principles
 Atraumatic technique:
 To maximize the healing potential and to avoid adhesions
 The tendon and surrounding tissues must be handled as
delicately as possible and kept moist
 Precise instruments are needed.
 Must be done under loupe magnification
 Early motion increases tendon strength, decreases adhesions,
increases excursion, and improves nutrition through the pumping of
synovial fluid.
 If both FDS and FDP are lacerated in zone II, both should be

39. Incisions
- Depend on
- Direction of initial laceration
- Need to expose other injured
structures
- Surgical preference
 Factors
 Avoid crossing joints at 90 deg
 Preference - Existing lacerations
 Need to expose other

41. Tendon Retrieval
 Retraction often limited to A1/A2 pullet region by vinculae
 If lacerated proximal to vinculae or if vinculae disrupted, tendon
ends may retract into plam
 If proximal stumps have retracted into the palm the correct
orientation of FDS and FDP must be re-established (such that FDP
lies volar to Camper’s Chiasm
 Avoid trauma to synovial sheath lining
 Forcep/hemostat/skin hook if proximal stump visible
 Proximal to distal milking
 Suction catheter

42. ZONE 1 INJURIES: Jersey Finger
 Involves only FDP
 If the distal stump is too small to allow the placement of
adequate sutures an osteo-periosteal flap is raised at
the base of the distal phalanx

43. Tendon Advancement
•An unlocked Tajima-
type suture of 3-0
polypropylene is
placed in the proximal
tendon stump
•The suture is brought
out through the nail
bed and a tie-over
button is used

44. Jersey Finger

45. Leddy Classification
 Type I: Retraction into palm
 Type II: Retraction to PIP level
 Type III: Bony avulsion (tendon
attached)
 Type IV: fracture and avulsion of

46. Tendon Advancement
 Previously advocated for zone 1 repairs, as moving
the repair site out of the sheath was felt to decrease
adhesion formation
 Disadvantages
 Shortening of flexor system
 Contracture
 Quadriga effect

47. Quadriga Effect
 If FDP tendon advanced too distally( > 1cm)
 Entire muscle bells gets pulled distally. Creates tension
in the other “yoked” tendons of FDP.
 Tendon excursion of FDP of other digits is limited

48. Zone 2 Injuries
 Zone 2: Deep and superficial
flexor gliding inside tendon
sheets
 Traditionally “No man’s land”:
Stiffness after repair

49. Injury: Tendons Retract

50. Repair Techniques
 Ideal
 Gap resistant
 Strong enough to tolerate forces generated by early
controlled active motion protocols
 10-50% decrease in repair strength from day 5-21 post repair
in immobilized tendons
 Minimized (possibly eliminated) through application of early
motion stress
 Uncomplicated
 Minimal bulk
 Minimal interference with tendon vascularity

51. Core Sutures
 Current literature supports several conclusions
regarding core sutures
 Strength proportional to number of strands
 Locking loops increase strength but may collapse and lead
to gapping
 Knots should be outside repair site
 Increased suture callibre = increases strength
 Braided 3-0 or 4-0 probably best suture material
 Dorsally placed suture stronger and biomechanically
advantageous
 Equal tension across all strands

52. SUTURE MATERIAL
 Non-absorbable
 Most prefer a synthetic braided 3.0 or 4.0 suture,
usually of polyester material
 However, monofilament sutures like nylon and wire are
also used (e.g. Proline)
 Additional running, circumferential 5-0 or 6-0 nylon is
used ofte

53. Dorsal vs Volar
 Dorsal placement avoided due to tendon vascular
anatomy, but now diffusion felt to be primary source of
nutrition during healing
 Biomechanical advantage and increased tensile
strength found during finger flexion(less work of
flexion) with dorsal sutures
 Increase work of flexion with volar sutures

54. Circumferential Sutures
(EPITENON )
 Initially were designed to improve tendon glide
 Have been shown to add tensile strength (by 10–
50%) and gap resistance to repairs.
 Running locked, horizontal mattress,
epitenon/intrafibre, and cross-stitch have been shown
to be the strongest.

57. Kessler

58. Modified Kessler
(1 suture)
 Advantage: Only one
node inside the repair site
 Easier to use a
monofilament suture like a
4.0 Proline to re-
approximate tendon
edges

59. Kessler-Tajima
(2 sutures)

60. Cruciate 4 Strand Repair

61. Sheath repair
 Advantages
 Barrier to extrinsic adhesion formation
 More rapid return of synovial nutrition
 Disadvantages
 Technically difficult
 Increased foreign material at repair site
 May narrow sheath and restrict glide
NO CLEAR ADVANTAGE ESTABLISHED

62. Partial laceration
 No repair if 60 % of the tendon intact
 Potential complications:
 Triggering
 Tendon entrapment
 Evaluation for the risk of triggering; debride if necessary
 Dorsal block splinting for 6 to 8 weeks

63. Complications
 Stiffness
 Re-rupture
 Tenolysis may be required in an estimated
18% to 25% of patients
 No earlier than 3 months after repair
 If no ROM improvement for 1-2 months

64. 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).

65. POST-OP
REHABILITATION

66. Post –op Rehabilitation
 For flexor tendon injuries is divided into four groups on
the basis of the exercises instituted during the first 3 to 4
weeks aftertendon repair:
(1) Immobilization
(2) Early passive mobilization
(3) Early active extension and passive flexion
(4) Early controlled active flexion

67. Immobilisation:
Rarely is there an indication for immobilization after flexortendon
surgery
 Exceptions
1) children or
2) adults unable to cooperate with hand therapy,
3) unstable bone repair, and
4) concerns about the effect of tension on
microneurovascular repairs.

68. Immobilisation:
 Splint - wrist in neutral or slight flexion, the
MCP joints are significantly flexed, and the
interphalangeal joints are only slightly
flexed or extended.

69. Rehabilitation
 Mayer (1916)
 The operation should never be undertaken unless
the surgeon himself can perform effective
postoperative care
 Early motion should be instituted at the right time
 graded exercises should be used with corrective
splints

70. Rehabilitation
 Bunnel (1918)
 Postoperative immobilization
 Active motion beginning at 3 wks postop
 Suboptimal results by today’s standards
 Improved suture material/technique as well as
postoperative rehabilitation protocols

71. Rehabilitation
 Kleinert (1950s)
 Posterior splint, wrist in flexion
 Rubber bands from fingernails to volar wrist area hold
fingers in flexion
 Patient able to actively extend against rubber bands
(within confines of splint)
 Fingers pulled passively back into flexion
 Used widely since with some modifications
 Showed superior results with primary repair vs
delayed grafting

72. Rehabilitation
 Tendon excursion
 MP motion = no flexor tendon excursion
 1.5 mm of excursion per 10 degrees of joint
motion for DIP (FDP) and PIP (FDS, FDP)
 These values decrease after repair by approx.
65% (DIP motion) and 10% (PIP motion)

73. Early Motion Protocols
 Modified Kleinert: Active extension, passive flexion by
rubber bands.
 Duran: Controlled Passive Motion Methods
 Strickland: Early active ROM

74. Modified Kleinert:
 It uses active extension with passive flexion by a dorsal
extension blocking splint with rubber bands running from
the fingertips (nails) to the volar wrist or forearm
 The rubber bands keep the patient from flexing the digits
against resistance
 During active extension, reciprocal relaxation of the
extrinsic flexors should decrease the tension on the
tendon repair

75. Modified Kleinert

76. Modified Kleinert
 After 3 to 4 weeks, the dorsal splint is removed but the
rubber bands are maintained
 Wrist range-of-motion exercises are started and finger
exercises continued

77. Duran Protocol
 Dorsal Splint in 20 deg wrist flexion
 No rubber bands
 Passive flexion
 Designed in response to notion 3-5mm of
tendon gliding sufficient to prevent restrictive
adhesions

78. Duran protocol

79. Rehabilitation
 Strickland
 Uses a 4 strand repair with epitendinous suture
 Dorsal blocking splint with wrist at 20 deg of flexion
 Supervised active ROM starts POD #3
 Unsupervised AROM at 4 weeks
 Rarely used, because it requires a pretty extensive
“bulky” repair to allow for early active ROM. A lot of
surgeons thinks that too much suture material may be
problematic for tendon healing

80. MGH Protocol

81. MGH Protocol

82. MGH Protocol

83. MGH Protocol

84. Children
 Usually not able to reliably participate in
rehabilitation programs
 No benefit to early mobilization in patients
under 16 years
 Immobilization >4 wks may lead to poorer
outcomes

85. COMPLICATIONS

86. Complications
 Short term:
 Infection
 Injury to neurovascular structures or pulley system
 Abnormal scarring
 Long term:
 Adhesion
 Rupture
 Joint contracture
 Triggering

87. Complications
 Adhesions
 Most common complication despite early motion
protocols
 Tenolysis when patients progressive gain in digital
motion has plateaued, usually 3- 6 months after repair

88. Complications
 Tendon rupture
 Noted by the patient at “popping” in the hand
 7-10 days postop when tensile strength is weakest
 MRI may help in diagnosis
 Flexion contracture
 FDP advancement more than 1 cm may lead to
flexion contracture and weakened hand grip because
of quadrigia effect

89. THANK YOU