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Flexor Tendon Injuries
Flexor Tendon Injuries
• 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
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
Anatomy
• Extrinsic flexors– Superficial group
• PT, FCR, FCU, PL
• Arise from medial
epicondyle, MCL,
coronoid process
Anatomy
• Extrinsic Flexors– Intermediate group
• FDS• Arises from medial
epicondyle, UCL, coronoid process
• Usually have independentmusculotendinous originsand act independantly
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 origins
Anatomy
• Carpal tunnel– 9 tendons– Median
nerve
Anatomy• Flexor sheaths
• approx distal palmar crease
– Predictable annular pulley arrangement
• Protective housing• Gliding surface• Biomechanical
advantage• Synovial layers
merge at MP level
• Flexor tendons weakly attached to sheath by vinculae
Anatomy
• Camper’s Chiasma
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)
Tendon Nutrition
• Dorsal vascularity• Avascular zones
– FDS (over proximal phalanx
– FDP (over middle phalanx)
• Nutrition vital for rapid healing, minimization of adhesion and restoration of gliding
Tendon Healing
• Inflammatory phase (0-5 d); fibroblastic phase (5d – 6wks); remodelling (6wks-9mos)
• Intrinsic vs extrinsic healing
• Balance between the two determines amount of extrinsic adhesion vs intrinsic tendon healing
Tendon Healing
• Factors affecting tendon healing, and adhesion formation– Surgical technique
• decreased vascularity• gapping
– Postoperative motion (passive, active)
Tendon Adhesion
• Increased adhesion formation with:– Traumatic/surgical injury
• Crush injuries
– Ischemia• Disruption of vinculae
– Immobilization– Gapping at repair site– Excision/injury to flexor sheath components
• Debate over benefit of sheath repair
Tendon Adhesion
• Experimental attempts to minimize adhesion formation– Oral: steroids, antihistamines, NSAIDS– Topical: beta-aminoproprionitrile,
hydrocyprolins, hyaluronic acid, collagen solutions, fibrin
– Physical: silicone/cellophane wrapping, polyethylene tubes, interposed sheath flaps
• Varying lab success but none proven definitively or adopted into clinical practice
Diagnosis
• History
Diagnosis
• Physical exam
• Abnormal resting posture
• Absent FDP / FDS function
• Associated digital nerve and digital vessel injury
• Discuss nature of injury and postoperative course with patient
Zones of Injury
FDS Insertion
Flexor Sheath(proximal)
TCL(distal edge) Carpal Tunnel
Flexor Tendon RepairTiming
• Delayed equal or better than emergent repair– Acute or subacute acceptable– Tendon deterioration/shortening after several
wks– Delay several days if wound infected
Incisions
• Factors– Avoid crossing joints
at 90 deg.– Preference– Existing lacerations– Need to expose other
structures
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• This is effect is minimized (possibly eliminated)
through application of early motion stress
– Uncomplicated– Minimal bulk– Minimal interference with tendon vascularity
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
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 sheathand restrict glide
• Presently, no clear cut advantage to sheath repair has been established
Partial Lacerations
• Controversy in past as partial lacerations were felt to predispose to entrapment, triggering and rupture
• Repair if > 50%
• Some advocate repair of partial lacerations > 60%
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• Quadregia effect• Little excursion distally, therefore adhesions near
insertion less of an issue
Tendon Excursion
Summary
• Strong gap resistant repair• 4 strand, locking epitendinous (or
equivalent), 3-0 suture needed for early active motion– 4-0 suture, modified Kessler, running
epitendinous suture adequate for more conservative protocols
• No sheath repair• Large grasping/locking loops
FDP Avulsions
• Commonly male athletes
• Forced extension at DIP during maximal flexion (jersey finger)
• Often missed due to normal xray and intact flexion at MP and PIP– Opportunity for FDP reinsertion lost if
treatment delayed
FDP Avulsions
Leddy and Packer
FDP Avulsions
- Type 1: zig-zag exposure- Tendon delivered through
pulley system with catheter passed retrograde
- Fixed to base of phalanx with monofilament suture through distal phalanx and nail plate and tied over button
- Fix within 7-10 days before tendon degeneration and myostatic shortening occurs
FDP Avulsions
- Type 2: small bony fragment retracts to A3 level- Can fix up to 6 wks
post injury (less shortening)
- May convert to type 1 if tendon slips through A3 pulley and into palm
- Use same technique as for type 1
FDP Avulsions
- Type 3: large bony fragment retracts to A4 level- Bony reduction and
fixation of fragment
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
Reconstruction
Single Stage Tendon GraftingZone 2
• Indications– Delayed treatment making end to end repair
impossible• Patient factors prevent repair• Late referral, missed tendon laceration or avulsion
– Supple joints with adequate passive ROM
Single Stage Tendon Grafting Zone 2
• Technique– 1 cm distal FDP stump left intact– 1 cm of FDS insertion left intact (decreased
adhesion formation vs granulating insertion site)
– Tenodesis of FDS tail to flexor sheath (10-20 deg of flexion) optional
• Hyperextension at PIP in absence of FDS tendon occurs occasionally
Single Stage Tendon Grafting Zone 2
• Technique– Graft donors
• Palmaris longus• Plantaris• Long toe extensors• (FDS)• (EIP)• (EDM)
Single Stage Tendon Grafting Zone 2
• Technique– Graft passed through pulley system
• Atraumatic technique
– Distal fixation with tension set proximally or proximal fixation first
– Multiple methods for fixation of graft ends
Single Stage Tendon Grafting Zone 2
• Technique– Distal
juncture
Single Stage Tendon Grafting Zone 2
• Technique– proximal
juncture
Pulvertaft weave creates a stronger repair vs end to endtechniques, and allows for greater ease when setting tension
Single Stage Tendon Grafting Zone 2
• Setting tension– GA
• With wrist neutral• Fingers fall into semi flexed position (slightly less
than ulnar neighbour), allowing estimation of tension
– Local anesthesia, active flexion– Electrical stimulation
• Bunnel – “tendons shrink”• Pulvertaft – “tendons stretch”
Secondary Reconstruction Zone 1
• Zone 1 (functioning FDS)– Eg. Late presentation of FDP avulsion– DIP fusion– Tendon graft
• Risks damaging FDS function through injury/adhesions in a very functional finger
• ? Young patients, supple joints, need for active DIP flexion
Secondary Reconstruction Zones 3, 4 and 5
• Usually associated with 3 – 5 cm gap– Interposition graft– FDS to FDP transfer– End to side profundus juncture
Two Stage Reconstruction
• Primary grafting likely to give poor result, but salvage of functioning finger still desirable
• Sub-optimal conditions– Extensive soft tissue scarring
• Crush injuries• Associated fractures, nerve injuries
– Loss of significant portion of pulley system
Two Stage Reconstruction
• Patient selection– Motivated– Absence of neurovascular injury– Good passive joint motion
• Balance benefits of two additional procedures in an already traumatized digit with amputation/arthrodesis
Two Stage Reconstruction
• Stage 1– Excision of tendon remnants
• Distal 1 cm of FDP left intact, remainder excised to lumbrical level
• FDS tail preserved for potential pulley reconstruction
– Incision proximal to wrist• FDS removed/excised• Hunter rod then placed through pulley system and
fixed distally (suture or plate and screw – depending on implant)
Two Stage Reconstruction
• Stage 1– Rod extends proximally to distal forearm in
plane between FDS and FDP– Test glide– Reconstruct pulleys as needed if implant
bowstrings
Two Stage Reconstruction
• Stage 1– Postop
• Start passive motion at 7 days• Continue x 3mos to allow pseodosheath to form
around implant• Before stage 2 joints should be supple, and
wounds soft
Two Stage Reconstruction
• Stage 2 – implant removal and tendon graft insertion– Distal and proximal incisions opened– Implant located proximally and motor selected
(FDP middle/ring/small, FDP index)– Graft harvested, sutured to proximal implant
and delivered distally• Fixed to distal phalanx with pull out wire over
button
Two Stage Reconstruction
• Stage 2 – implant removal and tendon graft insertion– Proximally sutured to motor with pulvertaft
weave
• FDS transfer from adjacent digit described• Obviates need for graft• Difficulty with length/tension
• Postop• Early controlled motion x 3 wks, then slow
progression to active motion
Pulley Reconstruction
• Pulley loss– Bowstringing = tendon taking shortest
distance between remaining pulleys– Biomechanical disadvantage
• Excursion translates into less joint motion
– Adhesions/rupture at remaining pulleys due to increased stress
– A2 and A4 needed (minimum) • Most biomechanically important• Some authors advocate reconstructing a 3 or 4
pulley system for optimal results
Pulley Reconstruction
• Most done in conjunction with a two stage tendon reconstruction
• Can be done with single stage tendon graft
• generally if extensive pulley reconstruction is required it is better to do a two stage procedure
Pulley Reconstruction
• Methods– Superficialis tendon
• Insertion left intact• Remnant sutured to original pulley rim, to
periosteum, or to bone through drill holes
– Tendon graft• Sutured as above• Passed through hole drilled in phalanx (risk of
fracture)• Wrapped around phalanx (requires 6-8 cm of graft)
Pulley Reconstruction
Pulley Reconstruction
• Methods– Extensor retinaculum
• Excellent gliding surface• Difficult to harvest the 8-6 cm required for fixation
around phalanx
– Artificial materials• Dacron, PTFE, nylon silicone• Due to abundant atogenous material and
disadvantages of artificial materials, this has not become common clinical practice
• May be stronger in long term vs autogenous
Tenolysis
– Release of nongliding adhesions for salvage in poorly functioning digits with previous tendon injury
– Avoid in marginal digits• May not tolerate additional vascular/neurologic
injury
– May need concomitant collateral ligament release, capsulotomy
– Prepare patient for possible staged reconstruction
Tenolysis
• Timing– 3-6 mos. Post repair (minimum)– Plateau with physiotherapy
• Anesthesia– Local with sedation
• Allows patient participation• Tests adequacy of release• Motivates patient
Tenolysis
• Technique– Zig zag incisions– Adhesions divided maintaining non-limiting
adhesions– Pulleys reconstructed as needed
• If extensive or not possible convert to staged reconstruction
– Immediate motion postop.