FLEXOR TENDON INJURIES James M. Steinberg D.O. Garden City Hospital

1
FLEXOR TENDON INJURIES James M. Steinberg
D.O.Garden City Hospital
2
Introduction

• One of the most common soft tissue injuries of
  the hand
• Repair of flexor tendon injuries continues to be
  a challenging problem
• Appreciation of flexor tendon anatomy is a must
  prior to any repair
• Repairs used to perform so poorly referred to as
  surgical no-mans-land

3
Tendon Anatomy

• Fascicles of long, narrow, spiraling bundles of
  tenocytes and type I collagen fibers
• Fascicles covered by thin visceral and parietal
  adventitia, paratenon
• Paretenon contains fluid similar to synovial
  fluid
• Flexor tendons are enclosed in sheaths lined by
  visceral and parietal synovial layers
• Attached to the sheath weakly by filmy
  mesenteries composed of vincula

4
Pulley System

• Overly the synovial sheath
• Includes palmar aponeurosis (PA), five
  annular pulleys (A1-A5), three cruciate pulleys
  (C1-C3)

5
Pulley System

• PA pulley improves mechanical efficiency of
  sheath system
• Annular pulleys prevent tendon bowstringing
• Cruciate pulleys collapse to permit annular
  pulleys to approximate each other during flexion
• Thumb has 2 annular pulleys (A1 at MCP and A2 at
  IP) and an oblique pulley (lies between A1 and
  A2)
• Oblique pulley is the most important
  functionally, loss causes decrease in IP motion

6
Flexor Digitorum Superficialis

• Originates from the medial epicondyle, coronoid
  process, and palmar proximal radius
• Superficialis muscle divides into 4 bellies in
  mid forearm allowing for independent flexion at
  PIP
• Four tendons arise in mid forearm and pass
  through the carpal tunnel palmar to the profundus
  tendons
• FDS and the intrinsic muscles combine for
  forceful flexion

7
Flexor Digitorum Superficialis

• At proximal third of prox. phalanx the FDS splits
  to pass around the profundus (FDP)
• Two slips reunite deep to the profundus in a
  region known as Campers Chiasma

8
Flexor Digitorum Profundus

• Originates at proximal 2/3 of the ulna and
  interosseous membrane
• Muscle divides in mid forearm into 2 bellies
• radial belly profundus tendon to index finger
• ulnar belly profundus tendon to long, ring,
  middle
• Tendons pass through the split in the FDS and
  insert into the base of the prox. 1/3 of the
  distal phalanges
• FDP is the primary digital flexor

9
Flexors of the Thumb

• Flexor pollicis longus (FPL) flexes the IP joint
• Flexor pollicis brevis (FPB) flexes the MCP joint
• FPL travels within the carpal tunnel

10
Flexor Zones

• Zone I FDS insertion to FDP insertion
• Zone II A1 pulley to the insertion FDS (No
  Mans Land)
• Zone III Distal border of the transverse carpal
  ligament to A1 pulley
• Zone IV Transverse carpal ligament, (within the
  carpal Tunnel)
• Zone V Proximal border of the transverse carpal
  ligament to musculotendinous junctions

11
Diagnosis

• Examiner maintains the other digits in full
  extension
• FDS function assessed with independent active
  flexion of the PIP joint
• FDP function determined by active flexion of
  the DIP joint
• FPL function active flexion of the IP joint of
  the thumb

12
Diagnosis

• Abnormal resting position of the hand may
  indicate flexor tendon injury
• Squeeze flexor muscles in the forearm
• Helpful in the unconscious or noncompliant
  patient

13
Tendon Healing

• inflammatory phase 48-72hrs
• fibroblast/collagen producing phase 5-28 days
• remodeling phase which continues for about 112
  days

14
Tendon Healing

• inflammatory phase 48-72hrs
• fibroblast/collagen producing phase 5-28 days
• remodeling phase which continues for about 112
  days

15
Tendon Repair

• Primary or delayed primary closure advocated for
  all zones
• Contraindications for primary repair
• contaminated wounds
• severe crush or segmental tendon injuries
• loss of palmar skin
• extensive damage to pulley system

16
General Considerations of Repair

• Knowledge of digits position at time of injury
• Adequate exposure of proximal and distal tendon
  ends
• mid lateral or palmar zig-zag inscions

17
Characteristics of an Ideal Repair

• Easy placement of suture
• Secure knots
• Smooth juncture of tendon ends
• Minimal gapping at repair site
• Minimal interference with tendon vascularity
• Sufficient strength throughout healing to allow
  for early ROM

18
Repair

• Tenorrhaphy in zones I and II most demanding
• Numerous techniques have been described
• strength of repair is proportional to the number
  of suture strands that cross repair site
• locking loops contribute little strength
• repairs rupture at suture knots
• synthetic 3-0 or 4-0 braided suture works best

19
Techniques

• Bunnell stitch
• Crisscross stitch
• Mason-Allen stitch
• Becker bevel repair
• Kessler grasping stitch
• Modified Kessler
• Tajima modification of Kessler (double knots)

20
Zone I Repairs

• Vinculum longus is usually intact preventing
  retraction proximal to the A4 pulley
• More than 1cm of profundus advancement results in
  unacceptable flexion contractures
• Need at least 1cm of the distal stump FDP for
  primary repair--consider insertion into the
  distal phalanx

21
Zone II Repairs

• Laceration usually between the A2 and A4 pulleys
• Often has significant proximal retraction
• wrist and MCP at max. flexion
• milk flexor muscle bellies
• 1 or 2 passes with a tendon retriever under the
  A2 pulley

22
Tendon Repair

• Studies by Wade and Lin have demonstrated that a
  running or locked epitendinous sutures increases
  tensile strength of the repair
• Sheath repair remains controversial
• repair provides nutrition with synovial fluid
• Lister and Tonkin found no benefit with closure
• Principles of repair applied to all zones

23
Partial Tendon Lacerations

• Bishop etal. demonstrated that tendon lacerations
  of 60 or less should not be sutured
• Klienert etal. based on cross sectional area
• lt 25 trim edges
• 25-50 repair with simple suture
• gt50 repair with modified Kessler

24
Postoperative Management

• Dorsal splint
• 20-30 degrees of palmar flexion at wrist
• 45-70 degrees palmar flexion at MCP
• extended IP joints
• Dynamic splint (Kleinert)
• rubber band attached to finger nail
• allows for passive flexion against which the
  patient actively extends

25
Standard Rehabilitation Protocol

• Dorsal splint for 6 weeks
• Passive exercises at day 3-4
• Gentle active exercises in 3-4 weeks
• Active extension out of splint at 6 weeks
• Resistive exercises at 8 weeks

26
Complications

• Rupture
• Tendon adhesions
• Triggering
• Bowstringing

27
Summary

• A thorough understanding of tendon anatomy and
  physiology, atraumatic surgical technique, and a
  well designed post-op therapy regiment are a must
• Most hand surgeons advocate a four strand core
  stitch along with a continuous peripheral
  epitendinous suture
• Studies by Gualt, Ikuta, and Savage revealed good
  to excellent results in 69-90 of patients
• Rapid advances continue to occur in flexor tendon
  surgery, and better techniques will lead to
  improved outcomes