Flexor tendon injuries
DR.M.M.Basumbuko (Medical intern)
Department of Surgery and Orthopaedics
Outline
Definition
Anatomy
Classification
Examination
Examination of flexor tendons and identifying injuries
Tendon repair
Post operative care
Conclusion
Tendon-a flexible but inelastic cord of strong
fibrous collagen tissue attaching a muscle to a
bone.(70% collagen) used for movement.
Anatomy
FDP: Origin; antero-medial ulna, IOmembrane
FDS: Origin; 2 heads. radius and ulnar heads
Divided into muscle belly in mid forearm
Insertion
FDS divided into two slips, wrapping around
FDP,reunite at Camper’s chiasma
Continues to insert along the proximal half of
the middle phalynx
FDP passes through chiasma to insert at
proximal base of distal phalynx
Zones of flexor tendons in hand
Sheaths
Visceral and parietal synovial layers encloses the
tendons
Pulleys; A2 and A4 arise from periosteum of
proximal and middle phalynx
Examination of injured flexors
Careful examination of the neurovascular status
of the hand precedes the evaluation of tendon
function.
Even when gross deformity is absent, the
posture of the hand often provides clues as to
which flexor tendons are severed.
When both flexor tendons of a finger are
severed, the finger lies in an unnatural position of
hyperextension,especially compared with
uninjured fingers.
Examination
Flexor tendon injuries can be tentatively confirmed by several
passive manoeuvres;
Passive extension of the wrist does not produce the normal
flexion of the fingers.
If the wrist is flexed, even greater unopposed extension of the
affected finger is produced.
Gentle compression of the forearm muscle mass at times shows
concomitant flexion of the joints of the uninvolved fingers.
With the proximal interphalangeal joint stabilized, the
flexor digitorum profundus is presumed severed if the
distal interphalangeal joint cannot be actively flexed.
• If neither the proximal nor the distal interphalangeal
joint can be actively flexed with the
metacarpophalangeal joint stabilized, both flexor
tendons probably are severed.
The method used to show the transection of FDS with an
intact FDP involves maintaining the adjacent fingers in
complete extension, anchoring the profundus tendon in the
extended position, and removing its influence from the
proximal interphalangeal joint.
When a flexor superfcialis tendon has been severed, and the
two adjacent fingers are held in maximal extension,flexion of
the interphalangeal joint usually is impossible
Exception is the result of the independent function of the index
finger FD-Polices a technique advocated by Lister is helpful.
The patient is requested to pinch and pull a sheet of paper with
each hand, using the index fingers and thumbs. In the intact finger,
this function is accomplished by the FDP .
If a wound is located at the level of the wrist, the joints of a finger can
be actively flexed even though the tendons to that finger are
severed. This is the result of intercommunication of the flexor
profundus tendons at the wrist, particularly in the Little and ring
fingers.
Classification
Leddy and Packer ;
Profundus avulsion classification
• Type I: FDP tendon is avulsed from its insertion and retracts
into the palm
• Type II: The profundus tendon is avulsed from its insertion,
but the stump remains within the digital sheath
Type III: A bony fragment is attached to the tendon stump,
which remains within the flexor sheath.
Zone 1 injuries
Leddy type I injuries require early (within 3
weeks)diagnosis and treatment. Although all
flexor tendon avulsion injuries are best treated
early, Leddy type II and III injuries may be
amenable to later repair.
Direct tendon repair is preferable if there is at least 1
cm of distal tendon stump.
Tendon repair to bone is done if there is less than 1
cm of distal tendon stump. Either suture anchors or
pull out suture and button constructs may be used.
Bone site should be observed directly before final
knot tying to ensure the tendon is well seated on the
repair footprint (distal phalanx).
Zone 2
Primary repair in the fibroosseous sheath (Bunnell’s “no
man’s land”), which was controversial but is now widely
accepted
Primary repairs at this level frequently fail because of
adhesions in the area of the pulleys.
If the timing of tendon repair is in doubt, the wound should
be cleaned and the repair made later by an experienced
surgeon.
Routine tendon repairs are preferably done no
later than 7 days after injury.
After 6 weeks, primary repair is unlikely to be
possible
Zone III
At zone III, the muscle bellies of the lumbricals and the
tendons frequently are interrupted. If conditions permit,
primary repair of sharply severed nerves is crucial
because delaying the repair even a few weeks results in
significant gaps between the nerve ends.
If wound conditions preclude tendon and nerve repair,the
ends of the tendons and nerves are sutured to adjacent
fascia to prevent undue retraction.
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).
Zone IV, V
All tendons and nerves in zone IV can be
repaired primarily when wound conditions are
satisfactory
Because zone V is proximal to the transverse
carpal ligament, tendon gliding after repair
usually is better here than in more distal zones
Partial tendon lacerations;
After partial tendon lacerations, complications reported by many
authors include rupture, triggering, and tendon entrapment.
• A tendon with 60% laceration can retain 50% or more of strength,
90% laceration can retain only slightly more than 25% of its strength.
If a tendon is lacerated 60% or more,treated the same as a complete
transection.
If the laceration is less than 60%,evaluated for
the risk of triggering. If triggering is seen, the flap
of tendon is smoothly débrided, and the flexor
sheath is repaired to help avoid entrapment or
triggering of the flap in the defect in the flexor
sheath.
Tendon Repair
Six characteristics of an ideal tendon repair:
(1) easy placement of sutures in the tendon,
(2) secure suture knots,
(3) smooth juncture of tendon ends,
(4) minimal gapping at the repair site,
(5) minimal interference with tendon vascularity, and
(6) sufficient strength throughout healing to permit application of early
motion stress to the tendon.
Timing
1.Primary repair
Golden period
With in 24hrs in a clean wound
Best results
2.Delayed primary repair
24-10 days
Done: suspicion of infection , viability questionable or came late
3.Secondary repair: 10-14days up to 4wks
4.Late secondary
After 4 wks
Delayed equal or better than emergent repair
Tendon deterioration/shortening after several
wks
Delay several days if wound infected
Types of repairs
Stages of tendon healing
Stage 1; 0-4 weeks
• Encourage active extension of fingers hold for 10 counts and
use rubber bands to passively flex the fingers. 10 repetitions
every hour.
Make sure PIP joint contracture does not develop
StageII; 4-6 weeks
Supervised active flexion
Encourage to do active flexion and extension
Stage III; 6-8 weeks;
Bivalve cast, suture removal, dorsal POP slab
Active flexion and extension within the slab
Each day increase 10 degrees of extension by breaking
the slab at MCP joint
Isolation of FDS and FDP exercises using Bunnell’s
block.
Stage IV; 8-10 weeks;
Volar cock up splint, wrist in neutral
Encourage active flexion and extension of all
fingers within the splint
Light activities
Home self care
Post op care;
The wrist usually is positioned in neutral position with
the metacarpophalangeal joints in 90 degrees of
flexion and interphalangeal joints left in 180 degrees
extension.
Beginning on the 2nd or 3rd day after surgery, flexion
outrigger traction device is applied and active
extension exercises within the limitations of the splint
are encouraged.
Conclusion
Careful examination of the neurovascular status of the hand
precedes the evaluation of tendon function.
Even when gross deformity is absent, the posture of the hand
often provides clues as to which flexor tendons are severed.
Golden period is usually with in 24hrs in a clean wound.
When adequate tendon repair is done patients can gain full
function of the affected hand again.
References
Footer Text Greens operative hand surgery 6th
edition
Merk Manual
Medscape
Apley and Solomon 9th edition.