This document summarizes evaluation and treatment of flexor tendon injuries of the hand. Key points include: 1) Flexor tendon injuries are evaluated through examination of finger mobility and tendon function while isolating individual joints, and may include imaging studies. 2) Injuries are classified based on the zone of injury and degree of tendon retraction. Early repair within 3 weeks yields the best outcomes. 3) Surgical treatment involves meticulous repair of the tendon with core sutures and epitendinous sutures to maximize strength, followed by post-operative hand therapy to regain mobility.

1. Flexor Tendon
Injuries
of the Hand
David P. Moss, MD

2. 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

3. Wound inspection
• May see lacerated
tendon
• May be misleading
– Flexed fingers at injury
– Extended fingers at
examination

5. 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

6. FDP examination
• Isolate DIP joint by grasping middle
phalanx
• Ask patient to flex DIP

7. Imaging
• Xray
– Avulsion fractures (Jersey fingers)
– Foreign bodies
• MRI/Ultrasound
– More commonly used in delayed presentation
of closed injuries

8. Anatomy

9. Zones

10. • FDS decussation at
A1 pulley
• 2 FDS slips rotate
180° around FDP
• Slips rejoin at PIP –
Camper’s Chiasm
• Insert on P2

11. 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

12. 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

13. Treatment

14. Timing of repair
• 3 weeks
– Commonly referenced
– The earlier the better (easier)
• Emergent repair if impaired vascularity
• >3 weeks – possible reconstruction

15. Zone I
• Jersey finger,
lacerations

16. Leddy classification
Type 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

17. 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

18. Zone II: “no man’s land”

19. • Historically poor results
• Adhesions, limited motion
• Fraught with complications

20. Core suture
• Repair strength directly related to number
of core sutures
• At least 4 core sutures for early AROM
• Types: Kessler, Strickland, cruciate, etc.

22. Epitendinous Suture
• Enhances repair strength by up to 50%
• Smooths tendon, decreases bulk

23. Gap formation
• >3 mm gap → ↓ strength at 3 & 6 wks

24. 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

25. Partial tendon lacerations
• Repair if >60% lacerated
• <60% → debride if entrapped
– Hard to distinguish without direct visualization

26. On the horizon
• Fiberwire
– 4-0 looped
• Lubricants
– 5-Fluorouracil (mitotic
inhibitor)
– Hyaluronic acid

27. 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)

28. Swan Neck
• DIP flexion, PIP hyperextension
• Mallet + lax/injured PIP volar plate

29. Boutonniere
• DIP hyperextension + PIP flexion
• Central slip avulsion
• Triangular ligament injury → volar
migration of lateral bands

32. 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

33. • Causes:
– FDP laceration distal to lumbrical origin
• Lumbricals originate on FDP just distal to TCL
• Insert into extensor hood – act to extend IPs

34. • Causes:
– FDP graft too long
– Amputation distal to central slip insertion
– All due to altered tension of FDP – load
applied to lumbrical first
– Imbalance

35. Board points

36. 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

37. • 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

38. • APL – multiple tendon slips to release in
Dequervain’s dz
• TCL – floor of Guyon’s canal

39. Dual innervated muscles
• FPB – median and ulnar
• Lumbricals
– IF & MF – Median
– RF & SF – Ulnar
• Brachialis – Musculocutaneous & Radial