Flexor Tendon Injuries

of the Hand

David P. Moss, MD

Evaluation• Perform prior to digital block!

• Skin

• Posture – extended finger

• Is finger perfused?– Cap refill– Doppler signal– Digital Allen’s test

• Digital nerves – radial & ulnar

Wound inspection

• May see lacerated tendon

• May be misleading– Flexed fingers at injury

– Extended fingers at examination

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FDS examination

• Adjacent finger DIPs, PIPs, and MCPs are held in full extension to eliminate FDP action

• Ask patient to actively flex at PIP

• Perform each finger seperately

• Can not rule out partial tendon injury

FDP examination

• Isolate DIP joint by grasping middle phalanx

• Ask patient to flex DIP

Imaging

• Xray– Avulsion fractures (Jersey fingers)– Foreign bodies

• MRI/Ultrasound– More commonly used in delayed presentation

of closed injuries

Anatomy

Zones

• FDS decussation at A1 pulley

• 2 FDS slips rotate 180° around FDP

• Slips rejoin at PIP – Camper’s Chiasm

• Insert on P2

Pulleys

• A2 & A4 – Originate off P1 & P2– Most important to

prevent bowstringing

• A1, A3, A5 originate off palmar plates

• A2– Approximately 2 cm

long– Can resect up to 50%

if needed

Tendon nutrition• Parietal paratenon

– Passive nutrition by diffusion

• Vincula and bony attachments– Direct nutrition– Segmental nutrition

• Vincula may prevent retraction

• Vascularity dominance is deep surface of tendon– Consider with suture

placement– Biomechanically superior

to place suture deep

Treatment

Timing of repair

• 3 weeks– Commonly referenced– The earlier the better (easier)

• Emergent repair if impaired vascularity

• >3 weeks – possible reconstruction

Zone I

• Jersey finger, lacerations

Leddy classificationType I: retraction into the palm

– Repair in 7-10 days due to disrupted vascularity

• Type II: retraction to PIP joint– Vincula intact, prohibit further retraction

– Repair up to 6 weeks

• Type III: avulsed with volar lip of P3– Can not retract past A4 pulley (DIP joint)– Repair up to 6 weeks

• Type IV: tendon avulsed off bony fragment

Zone I Fixation

• Leddy I: repair within 3 weeks

• Leddy II or III: repair up to 6 weeks

• Bone anchors into P3– 1 or 2 microanchors

• Pull through sutures over nail plate or button

Zone II: “no man’s land”

• Historically poor results

• Adhesions, limited motion

• Fraught with complications

Core suture

• Repair strength directly related to number of core sutures

• At least 4 core sutures for early AROM

• Types: Kessler, Strickland, cruciate, etc.

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Epitendinous Suture

• Enhances repair strength by up to 50%

• Smooths tendon, decreases bulk

Gap formation

• >3 mm gap → ↓ strength at 3 & 6 wks

Post-op care

• Splint 3-5 days to allow swelling to subside

• Then early AROM– May increase repair site strength– Commitment to hand therapy is critical

• PROM also used

• Advance activity over 2-3 months

• Unrestricted use at 3 months

Partial tendon lacerations

• Repair if >60% lacerated

• <60% → debride if entrapped – Hard to distinguish without direct visualization

On the horizon

• Fiberwire– 4-0 looped

• Lubricants – 5-Fluorouracil (mitotic

inhibitor)– Hyaluronic acid

Quadriga • Uninjured fingers unable to fully flex

• Usually due to shortening of injured flexor

• Common FDP muscle belly to SF, RF, MF

• Flexion excursion of other fingers is limited by the shortest tendon (usually injured finger)

Swan Neck

• DIP flexion, PIP hyperextension

• Mallet + lax/injured PIP volar plate

Boutonniere

• DIP hyperextension + PIP flexion

• Central slip avulsion

• Triangular ligament injury → volar migration of lateral bands

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Lumbrical plus

• Paradoxical extension of IPs with attempted forceful flexion– IP extension – intrinsics– MCP flexion – intrinsics– IP flexion – FDP/FDS– MCP extension – EDC/EIP/EDQ

• Causes:– FDP laceration distal to lumbrical origin

• Lumbricals originate on FDP just distal to TCL

• Insert into extensor hood – act to extend IPs

• Causes:– FDP graft too long– Amputation distal to central slip insertion

– All due to altered tension of FDP – load applied to lumbrical first

– Imbalance

Board points

Anatomy

• Nerve compressions– Ulnar nerve (AMECF)

• Arcade of struthers• Medial intermuscular

septum• Epicondyle• Cubital tunnel• FCU

– Radial nerve (FLEAS)• Fibers off lat IM septum• Leash of henry• ECRB• Arcade of frohse• Supinator

• Median nerve (SLAPS)– Supracondylar process– Ligament of struthers

• SC process – med epicondyle

– Aponeurosis (lacertus fibrosis)

– Pronator– FDS

• EIP – last muscle innervated by PIN

• Parona’s space– potential space volar to PQ– Thenar space infection can communicate to

hypothenar

• Space of Poirier – weak space in volar carpal ligaments b/w RSC and RLT ligs

• Contents of carpal tunnel

• APL – multiple tendon slips to release in Dequervain’s dz

• TCL – floor of Guyon’s canal

Dual innervated muscles

• FPB – median and ulnar

• Lumbricals– IF & MF – Median– RF & SF – Ulnar

• Brachialis – Musculocutaneous & Radial