SURGICAL ANATOMY OF HAND AND IT’S INFECTIONS

Dr SD SanyalLt Col R Venkatnarayan

HAND ANATOMY

The hand is the region of the upper limb distal to the wrist joint.

It is subdivided into three parts: 1. Wrist 2.Metacarpus 3.Digits (five fingers including the thumb). The hand has an anterior surface (palm)

and a dorsal surface (dorsum of hand).

HAND

Palmar aponeurosis Blood supply Nerves Carpal tunnel Guyon’s canal Palmar spaces Nail anatomy

Hand

The palmar aponeurosis is a triangular-shaped condensation of deep fascia that covers the palm and is anchored to the skin in distal regions.

The apex of the triangle is continuous with the palmaris longus tendon.

Palmar Aponeurosis

Palmar Aponeurosis

Figure 4 Anatomy of the radial artery

Byrne, R. A. et al. (2012) Vascular access and closure in coronary angiography and percutaneous intervention

Nat. Rev. Cardiol. doi:10.1038/nrcardio.2012.160

Cutaneous Innervation of Ulnar Nerve

Cutaneous Innervation of Radial Nerve

Cutaneous Innervation of Median Nerve

All of the intrinsic muscles of the hand are innervated by the deep branch of the ulnar nerve except for the three thenar and two lateral lumbrical muscles, which are innervated by the median nerve.

Innervation of muscles

The carpal tunnel is formed anteriorly at the wrist by a deep arch formed by the carpal bones and the flexor retinaculum.

Carpal tunnel and structures at the wrist

Four tendons of the flexor digitorum profundus

Four tendons of the flexor digitorum superficialis

One tendon of the flexor pollicis longus

Median nerve

Structure and relations

Carpal Tunnel

Guyon’s Canal

1. Hypothenar compartment

2. Thenar compartment 3. Central compartment 4. Adductor

compartment 5.Interosseous

compartment

Compartments of palm

THENAR Abductor Pollicis Brevis Flexor Pollicis Brevis Opponens Pollicis

HYPOTHENAR Abductor Digiti Minimi Flexor Digiti Minimi Opponens Digiti Minimi

INTERMEDIATE Flexor tendons covered by Synovial

sheaths lumbricals Palmar arterial arches Branches of Median and Ulnar nerves

ADDUCTOR Adductor Pollicis

No well defined spaces inside the fascial compartments

Become apparent when there is collection of pus

Mid palmar septum/Intermediate palmar septum divide intermediate comp into Thenar & Mid palmar spaces

MidPalmar space Thenar space Hypothenar space Radial Bursa Ulnar bursa

Palmar Spaces

Anterior – Palmar aponeurosis, superficial palmar arch, flexor tendons of medial 3 digits covered in ulnar bursa and medial 3 lumbricals

Posterior - Fascia covering 3rd & 4th interossei and metacarpal bones

Medial – Medial Palmar septum Lateral - Midpalmar septum Proximal – distal margin of flexor

retinaculum Distal - medial 2 web spaces thru lumbrical

canals

Midpalmar space

Anterior - Palmar aponeurosis, superficial palmar arch, flexor tendon of index finger covered with synovial sheath, tendon of FPL

Posterior – fascia covering adductor pollicis

Lateral - Lateral palmar septum Medial MidPalmar septum. Proximal – distal margin of flexor

retinaculum Distal - 1st web space thru lumbrical

canal

Thenar Space

Posterior – 5th Metacarpal

Lateral – Hypothenar septum

Medial & Ant– Hypothenar Muscles

Hypothenar Space

Synovial sheath surrounding Flexor Pollicis Longus tendon

Extends from forearm( 2 cm prox to Flexor retinaculum) to base of terminal phalanx of thumb

Radial Bursa

Common synovial sheath surrounding tendons of Flexor digitorum superficialis and profundus

Extends from forearm( 2 cm prox to Flexor retinaculum) to mid palm level where it ends as cul-de-sac .

Continuous with digital sheath around flexor tendons of little finger

Ulnar Bursa

4 Subcutaneous spaces

From its free margin – extends to level of MCP joint.

CONTENTS - S/C fatSuperficial transverse metacarpal ligament, interosseous and lumbrical tendons, digital nerves and vessels.

Web Spaces

Nail AnatomyA. Nail plateB. LunulaC. RootD. SinusE. MatrixF. Nail bedG. HyponychiumH. Free edge

Hand Infections

Infection of the soft tissues surrounding the fingernail and is the most common infection of hand.

PARONYCHIA

Cause:◦ Inocculation of bacteria as a consequence of

minor trauma such as Nail bitiing Poor manicuring Small puncutre wounds.

Staph aureus is most common pathogen but anaerobes may also be involved.

UNCOMPLICATED INFECTION:◦ Oral antiboitics / Rest / Heat / Elevation

INFECTION WITH ABSCESS:◦ Localized to one nail fold;

Elevation of fold bluntly with a haemostat Using no 11 blade directing away from nail bed

through the insensate epithelium where abcess is pointing.

◦ Eponychia (involving proximal nail & one lateral fold; Elevating the eponychial fold and removal of loose

portion of nail plate to drain abscess and allow for secondary healing.

A felon is an abscess of the distal pulp of the thumb or finger.

FELON

Pulp Anatomy:◦ 15-20 longitudonal septa anchoring skin to distal

phalanx dividing the pulp into multiple closed compartments.

Pathophysiology:◦ Abscess formation within these small

compartments results in rapid development of swelling and throbbing pain, worsened by dependency.

Complications:◦ Necrosis of entire pulp◦ Extension of infection into;

Flexor tendon sheath Distal IP joint Distal phalanx.

Causes:◦ Mostly Puncture wound with foreign body, so

radiographs are mandatory. Pathogen:

◦ Staph aureus but gram –ve infection can also occur esp in immunocompromised patients.

Conservative Management: For early Felons…◦ Oral antiboitics◦ Rest◦ Warm Soaks◦ Elevation.

Herpex simplex virus infection can be:◦ Primary◦ Recurrent

Population at risk:◦ Children, adolesents with genital herpes infection◦ Health care workers with frequent exposure to

oral secretions. Must be distinguished from Paronychia and

Felon because incision and drainage is generally contraindiacted.

HERPETIC WHITLOW

Pathophysiology:◦ A prodromal phase of 24-72 hours of burning pain

prior to the development of skin changes.◦ Erythema and swelling◦ Formation of clear vesicles which sometimes

coalesce around nail fold.◦ Fluid may become turbid but not frankly purulent

unless bacterial superinfection occurs.◦ Pulp of affected digit is not tense as in felon.

Disease Course:◦ The process occurs over approx 2 weeks and

resolves over next 7-10 days. Diagnosis:

◦ Viral culture◦ Tzanck smear

Treatment: Generally conservative◦ Rest & Elevation◦ Anti inflammatory agents◦ Acyclovir in immunocompromised states.

Reccurence rates are around 20%.

Thenar space Midpalmer space (subtendinous space) Hypothenar space Dorsal subapeneurotic space Web spaces.

◦ Thenar and midpalmer spaces are clinically more important.

PALMER SPACE INFECTIONS

MIDPALMER SPACE INFECTION

THENAR SPACE INFECTION

A penetrating injury usually a splinter is the most common cause.

Staph aureus is the usual pathogen. Antiboitics / Rest / Heat / Elevation for early

infections but most cases need Surgical Drainage.

Key to success is adequate drainage while avoiding iatrogenic injury and subsequent scar contracutres.

Curved longitudonal incision in the palm. Take care to avoid injury to superficial

palmer arch and digital vessels. Wound packed open with daily dressing

changes. OR Irrigation catheter in proximal wound and a

penrose drain in distal wound for continous or intermittent irrigation.

Midpalmer space infection incisions and proceedures:

Combined dorsal and volar incisions. Take care to avoid injury to palmer

cutaneous branch of median nerve in proximal end of incision

And avoiding injury to motor branch of median nerve.

Post op care include◦ Splinting◦ Dressing changes◦ Catheter irrigation.

Thenar space infection incision and procedure:

Most serious hand infection. If left untreated;

◦ Destruction of gliding surfaces in sheath◦ Necrosis of tendons◦ Osteomyelitis◦ Amputation.

Ring, middle and index fingers mostly involved Staph aureus usual pathogen with few cases

due to haematogeneous spread of gonococcal infection.

TENOSYNOVITIS

KANAVEL cardinal sign of flexor tenosynovitis:

1. Fusiform swelling of finger2. Paritally flexed posture of digit3. Tenderness over entire flexor sheath4. Dipropotionate pain on passive extension.

PRINCIPLESOF MANAGEMENT

IV antiboitcs is the most common justification for hospitalization.

Continuous or intermittent wound irrigation.Frequent dressing changes.Three phases of treatment in cases of

severe infections where extensive debridement and complex reconstructions are needed.

INPATIENT CARE

Phase 1> Rapid infection control and staged debridement.◦ A second look surgery done in 24-48 hours.

Phase 2> Salvage of vital structures and soft tissue coverage.◦ With identification of structures that will later

require reconstruction. Phase 3 > Reconstructive Surgery.

◦ Once stable soft tissue coverage is achieved.

1. Incisions should never cross a flexion crease at a right angle

2. Avoid iatrogenic injury to critical structures1. Tendons2. Neurovascular bundles

3. Incision lengthening is usually needed and should be planned by making potential extensions with a pen.

OPERATIVE PRINCIPLES

4. Torniquet Control is helpful as infective process can lead to profuse bleeding.

o Finger Torniqueto Penrose draino Glove technique

oStandard Pnematic Torniquet with exanguinationo Esmarch bandageo Elevation of limb with digital pressure on brachial

artery.

a. REST (IMMOBILIZATION)o Limits opening of tissue plans restricting the

spread of infection.o Should be done in a functional position.

REST – HEAT - ELEVATION

b. HEAT (WARM MOIST SOAKS):o Maximum vasodilatory effect reached in 10 min.o Frequent soaks preferred over continuous

soaks.o Severe Infections:

o Moist hot towels with plastic barrier and a dry towel as insulator.

c. ELEVATION:o Reduces edema by improving venous/lymphatic

drainage.o Limb should be above level of heart for

dependant drainage.o Limb placed over chest or on a pillow while

sitting.

Position for Long Term Immobilization

Metacarpalphalangeal joints in 60 to 70 degrees of flexion

PIP and DIP joints extended

FelonsTreatment

FelonsTreatment

Location of Incisions:Index, middle & ring: ULNAR SIDEThumb & small: RADIAL SIDE

ParonychiaTreatment

Eponychia: Elevate eponychial fold and excise prox 1/3 of nail Lateral (paronychial) incisions may aid in separating the

nail base if not already separated

ParonychiaTreatment

2 basic approaches: Open vs. Closed

Open drainage: Decompression of the entire tendon

sheath via mid-axial & palmar incisions Wounds are left open to drain & heal

secondarily Rehab is prolonged; permanent finger

stiffness not infrequent Most useful for advanced cases where

resection of necrotic tendon is required

TenosynovitisSurgery

These incisions: ensure adequate drainage heal quickly Do not interfere with rehab

After removal of catheter and drains begin gentle passive & active ROM

TenosynovitisTreatment

Subfascial and Subpalmar spaceIncisions

Drain via volar or dorsal incisions in the 1st web space or both: Identify neurovascular structures unroof the adductor fascia to open

the abscess cavity irrigate & debride catheter in volar incision & close;

penrose in dorsal incision & close compressive dressing & plaster splint

Thenar Space InfectionsTreatment

Drain via wide palmar incisions with +/- resection of palmar fascia to ensure drainage of abscess cavity.

or may place irrigation catheter & drain and close primarily.

Midpalmar Space InfectionsTreatment

Closed irrigation using 2 incisions, a catheter & a drain as previously outlined.

Bursal InfectionsTreatment

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