Fingertip injuries

Question 1

Describe the anatomy of the finger tip

Answer 1

• defined as distal to the insertion of the FDP and terminal tendon
• volar skin is thicker, glaborous skin, with thicker stratum corneum
• pulp is fibro-fatty padding on volar aspect of finger tips for grip, pinch - maintained to distal phalanx by fibrous septae
• dorsal skin is thinner, non glaborous skin wiht minimal subucutaneous tissue
• dorsally there is the nail structure: perionychium, nail plate, germinal matrix, sterile matrix, hyponychium
• arterial supply trifurcates at DIPJ and sends a dorsal branch to nail fold, branch to tip, and to pulp
• there are glomus bodies which are AV shunts that are regulated sympathetically for temperature control
• veins are small, dorsal venules are extremely small until level of DIPJ
• nerves travel volar to arteries, both together below grayson ligament and above cleland ligament
• in mid-proximal phalanx, the nerve sends a dorsal branch to the dorsal middle and distal phalanx/digit
• at DIPJ the nerve also trifurcates, sending branches to nail fold, tip and pulp
• the pulp is richly innervated for sensory perception

Question 2

what is the lanula?

Answer 2

• lanula is the hypopigmented convex crescent seen at the proximal extent of the nail plate
• it indicuates persistent giant nuclei of cells of germinal matrix
• distal to lanula underlying nail bed is sterile matrix, generally not responsible for nail growth/production

Question 3

DESCRIBE NAIL GROWTH

Answer 3

• at the germinal matrix, onychocytes (nail producing cells) undergo proliferation, enlarge, the nucleus disintegrates, cells collapse and flatten; major role to contribution of keratin content
• at the dorsal roof of the nail fold, the same process occurs as in germinal matrix, but cells lose their nuclei more quickly, also adds shine
• along the sterile matrix there is some contribution to growth (< 10%), whereby further squamous cells are added to add strength, thickness; contributes only minor keratin and contributes to nail adhereence to bed

Question 4

describe classification of fingertip injuries

Answer 4

• many described / eponymous classification system
• useful classification system will outline involved/injuried structures as follows:
• geometry of injury
  
  • transverse
  • volar/dorsal/lateral oblique
• Soft tissue/skin/pulp injured
• Nail plate injured/involved; proximal or distal to lanula (defines involvement of germinal matrix)
• Bone exposed in wound
• Tendon exposed/injured
• Joint involved

Question 5

describe treatment goals for fingertip injury

Answer 5

• provide durable soft tissue coverage
• preserve sensation
• preserve length
• preserve nail appearance and function, prevent hook nail
• expedite return to work/leisure
• minimize discomfort during healing

Question 6

List the options available to reconstruction of fingertip injuries

Answer 6

• secondary intention
• 1’ closurewith suture approximation
• skin graft
• composite graft
• homodigital flap
• heterodigital flap
• regional flap
• microsurgical transfer or replantation

Question 7

discuss the use of healing by secondary intention w fingertip injries: indications, advantages, disadvantages, expected outcomes

Answer 7

• for defects < 1.5cm^2 (some say w no exposed volar bone)
• advantages: better sensation, glaborous skin, no donor morbidity, inexpensive, no secdonary joint stiffness or contracture from positioning while healing
• disadvantages: time to complete healing and return to work, hypersensitivity or dysesthesia, unstable scar (particularly if insufficient bony padding)
• expected outcomes: most healed within 3-6 wks; most back to full manual labour by 6-8 wks, aesthetic outcome acceptable (superior)

Question 8

discuss the use of skin grafts for coverage of fingertip injuries: indications, advantages, disadvantages, expected outcomes

Answer 8

• for injuries not amenable to 2’ intention and patient unable/unwilling to tolerate local/regional flap
• often taken from hypothenar eminence so glabour skins - FT graft (reinnervation possible)
• adv: easy, relatively fast, minimal donor morbidity, no contracture d/t position while healing
• disadv: often does not achieve protective sensation, may not expedite healing vs. 2’ intention

Question 9

discuss the use of composite grafts for fingertip reconstruction: indications, adv, disadv, expected outcomes

Answer 9

• children < 6-8years (best in < 2 years)
• adv: glaborous skin, optimize appearance, no donor morbidity, no contracture w position during healing, preserve length /avoid revision amputation
• disadv: unreliable healing/take with increased age, potential for stiff/flat/tough, painful, minimially sensate tip depending on extent of revascularization, risk of total failure

Question 10

what are factors to consider with fingertip injuries of soft tissue and exposed bone, when comparing use of flaps vs revision amputation

Answer 10

• significant exposed bone precludes use of 2’ intention, skin grafting, +/- composite graft
• options become loco-regional flap vs. revision amputation
• revision amputation
  
  • adv: early return to work, functional outcomes often similar, avoid contracture w/ positioning during healing, no donor site morbidity
  • disadv: loss of length, worst cosmetic result, patient psychosocial impact of amputation and stump
  • ideal for digits where length is less criticial (D2, 4, 5) or for patients that wish to return to work asap
• locoreginal flap
  
  • adv: optimal to preserve length, may preserve/restore sensation depending on flap, improved cosmesis vs. rev-amp, patient psychosocial outcome to avoid shortening or amputated appearance
  • disadv: donor site morbidity, may require sub-optimal position during healing and subsequent stiffness/contracture, protective sensation may or may not be achieved, cortical re-learning in adults rarely achieved
  • ideal to preserve length of thumb or long finger

Question 11

Define the perionychium

Answer 11

Composed of

• nail bed
• nail fold
• nail plate

Question 12

What structures make up the nail fold, plate and bed

Answer 12

Nail bed:

• Sterile matrix
• germinal matrix
• dorsal roof
• Lunula

Nail fold (Eponychium)

• dorsal roof
• ventral floor
• proximal mail plate

Question 13

WHat is the hyponichium

Answer 13

At junction of distal nail and epidermis of tip

= large mass of WBC and keratin

Fx: mechanical and immunological barrier

Question 14

What is the function of the nail plate

Answer 14

• protection
• tactile sensation
• thermoregulation
• cosmesis

Question 15

What are options for local/regional flap for fingertip injuries (>1cm2 with bone exposure)

Answer 15

• V-Y advancement (atasoy)
• lateral V-Y advancement (kutler)
• Dorsal reverse adipofascial flap
• cross finger
• reverse cross finger
• Thenar flap
• Homodigital neurovascular island flap
• homodigital reverse FDMA flap
• Heterodigital neurovascular island flap

Question 16

Describe cross finger flap

Answer 16

• Recon of volar defect with skin from adjacenet digit MP
• template defect on MP of adjacent digit, raise skin,adipose leaving paratenon behind. trasnpose to defect and inset.
• Sutre//kwire digits together, allow gentle AROM to preent significant stiffness
• divide 2wks
• Adv - better sensation than skin graft
• DisAdv - non glaborous skin, 2stage, donor site

Question 17

Describe Reverse cross finger flap

Answer 17

• for dorsal defects, harvesting adipofascial flap from adjacenet MP digit
• template defect, raise skin only with pedicle away from defect finger
• raise adipofascial flap, leaving paratenon with pedicle onside adjacenet to defect
• inset flap in to defect
• STSG defect flap and donor site gets skin that was raised initially
• Adv: thin supple coverage of dorsal defects w exposed joint/tendon
• Disadv - 2 stage, donor site morbidifty

Question 18

Describe the thenar flap

Answer 18

• for index and long finger defect
• Design flap 50%larger than defect and palce on most proximal portion of thenar skin to reduce PIP flexion
• designed as qaure H with proximal and distal flaps
• divide 2wks - proximal flap goes to defect and distla flap used to close donor site
• Adv: glaborous skin, no skin graft for donor
• Disadv - pip stiffness, 2 stage procedure

Question 19

What are local flap or regional flap coverage options for a thumb tip defect?

Answer 19

If no tendon/bone/joint exposed:

• skin graft (FT)
• 2’intention
• 1’closure approximation
• composte graft

If tendon/bone/joint exposed:

• Moberg flap
• Littler heterodigital neurovascular island flap
• cross finger flap (+/- sensory)
• Neurovascular island flap (kite flap)
• FDMA flap
• Great toe pulp flap

Question 20

Describe the moberg flap

Answer 20

• palmar advacement flap for the thumb volar defects - works on thumb b/c of dorsal arterial supply
• elevation of both NV bundles, provides good sensation and
• bila midaxial incisions, raise both NV bundles and all soft tissue directly off flexor sheath
• advacment improved if flex IP, backcut
• Adv: glaborous skin with good sensation
• Dsiadv IP stiffness, flap necrosis

Question 21

Describe cross finger flap for thumb

Answer 21

• for volar thumb defect, donor IS SKIN ON PP OF INDEX (not MP as in other digits)
• rest as cross finger flap

Question 22

Decribe the radial sensory cross finger flap

Answer 22

• For volar thumb defect, flap raised off index PP, dorsal branch of digital nerve raised and coapted to radial digital nerve of thumb
• pedicled flap requires incision down 1st web to identify dorsal branch

Question 23

Describe the neurovascular island (kite) flap

Answer 23

• Flap based on NV bundle
  
  • can be homodigital (direct island advancement or reverse flow based on connection proximal to DIPjt)
  • heterodigital (based on ulnar D3)
• Steps
  
  • template our defect on ulnar D3. Check vascular flow w digital doppler/allens test
  • dissect NV bundle before insicinc flap. Seperate and clip r to D4 CDA and dissect CDN back into palm to increase pedicle length
  • tunnel to thumb
  • donor site closure w STSG
• Adv: single step, sensate tissue
• DisADv cortical plasticity, donor site flexion contracture/scarring, flap necrosis, nerve injury

Question 24

Describe FDMA flap

Answer 24

• For thumb defect both volar and dorsal
• Located on dorsum of PP of index finger. Can be reverse flow or anterograde for thumb defect
• FDMA arises from deep br radial artery and runs along radial side of MC, under fascia and 1st DIO
• skin flap harvested above paratenon, pedice raised through fascia, not skeletonized
• Adv: single stage, sensate if superficial radial sensory br taken

Question 25

Describe free toe pulp trasnfer

Answer 25

* Neurosensory first web flap * A: distal communicating artery that connects FDMA or FPMA - raised off whichever is dominant * Sking flap terrirtory - lateral great toe to medial hemipulp of 2nd toe * N: deep peronal branch

Question 26

How do you mange a subungal hematoma

Answer 26

* \>50% of nail area- remove plate, drain and repair bed * \<50 - not a significant injury - punture hole in plate to drain hematoma for pain relief

Question 27

List options for management of finger tip injuries:

Answer 27

* Revision amputation * Secondary intention * S/FTSG * Random pattern flaps: rotation, advancement, transposition * Local homodigital flaps: Atasoy VY (volar); Kutler VY (bilateral), Moberg, reverse homodigital island flap * Local heterodigital: cross-finger, reverse cross-finger, Axial flag flap (F/SDMA over dorsal PP), Littler heterodigital NV island flap, thenar flap * Regional: reverse PIA, reverse radial forearm * Distant/free: free lateral arm, TPF, PIA, radial forearm, toe pulp, great toe

Question 28

List 3 options for the following finger tip injuries * transverse * dorsal oblique * volar oblique

Answer 28

* transverse: VY (Atasoy), VY (kutler), thenar flap * dorsal oblique: VY (Atasoy), reverse cross finger, revision amputation * volar oblique: Cross-finger, reverse homodigital island flap, thenar flap

Question 29

what are considerations for different digits when considering finger tip reconstruction

Answer 29

* thumb and long want to preserve length * thumb (ulnar side) and index (radial side) want to preserve / restore sensation

Question 30

what are the complications / sequellae of finger tip injuries?

Answer 30

* pain * hyperaesthesia, dysesthesia, hypoaesthesia, anaesthesia of tip/flap/scar * failure of cortical re-integration * cold hypersensibility * painful neuroma * stiffness / contracture