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Procedure
Practice 05/15/99 - Coding
Recommendations
Feature
Article 05/15/99:
The Hand
Anatomy
- Diseases and Injuries
- Surgical Procedures -
Closure Techniques for Traumatic
Hand Wounds
Injuries and diseases of hand structures are
frequent causes for office and emergency room visits and outpatient
surgery. This month, we review hand anatomy along with common
hand conditions, injuries, and surgical procedures.
Because of the hand's structural complexity, the anatomical
information that follows covers only major structures in an
effort to provide the reader with a general understanding
of hand anatomy and landmarks. The best way to understand
hand anatomy is to see it. You can view excellent anatomy
images on the web at: http://www.vesalius.com. Some of the
other web sites listed in the bibliography also have helpful
illustrations.
Bones
The fingers of one hand include 14 bones called phalanges.
Each phalanx has a base, a body (or shaft), and a head. The
thumb has a proximal and distal phalanx. The remaining fingers
have proximal, middle, and distal phalanges.
The five bones proximal to the phalanges are the metacarpals.
The metacarpals resemble miniature long bones and are numbered
one through five beginning with the thumb.
Eight carpal bones complete the skeletal structure of the
hand. These bones are arranged in two rows running transversely
across the width of the hand. Working from a lateral (thumb)
to medial (small finger) direction, the distal row of bones
(the row closer to the metacarpals) consists of the trapezium,
trapezoid, capitate, and hamate bones. In the proximal row
of carpals we find the scaphoid, lunate, triquetrum, and pisiform
bones.
Joints
and Ligaments
The bones in the hand require many joints with supporting
ligaments to connect and stabilize them. Interphalangeal (IP)
joints occur at the articulations of the distal and middle
phalanges (DIP joints) and between the middle and proximal
phalanges (PIP joints). The interphalangeal joints are strengthened
by collateral ligaments. Metacarpophalangeal (MCP) joints
are located at the articulations of the proximal phalanges
and metacarpals. Carpometacarpal (CMC) joints connect the
distal row of carpals to the metacarpals and are tightly bound
by ligaments to limit motion. The wrist joint is comprised
of the carpals and the distal ends of the two long bones of
the forearm, the radius and ulna. The joints between the forearm
and proximal row of carpals are the radiocarpal and ulnocarpal
joints, and the joint between the proximal and distal rows
of carpals is the mid-carpal joint. Short intrinsic ligaments
connect the dorsal surfaces of adjacent carpal bones and run
in a transverse direction across the width of the hand. On
the palmar surface, larger extrinsic ligaments span between
the radius and ulna and both rows of carpals. The radial collateral
ligament located in the wrist capsule connects the styloid
process of the radius to the scaphoid and trapezium. The ulnar
collateral ligament connects the styloid process of the ulna
to the pisiform and triquetrum. The triangular fibrocartilage
(TFC) is a triangular-shaped cartilage disc. It attaches to
the edge of the radius at the base of the triangle and to
the end of the ulna at the apex. The TFC provides a supportive
sling for the adjacent surfaces of the triquetrum and lunate.
Muscles and Tendons
The movements of the hand are accomplished by two sets of
muscles and tendons: the flexors bend the fingers and thumb,
and the extensors straighten the digits. The flexor muscles
are located on the underside of the forearm and are attached
by tendons to the phalanges. The extensor muscles are on the
back of the forearm and are similarly connected to the phalanges.
The thumb has two separate flexor muscles that move the thumb
in opposition and make grasping possible.
Anatomical
Landmarks
The following terms appear frequently in surgical procedure
descriptions. They describe landmarks within the hand and
can provide the coder with a clearer understanding of the
surgical procedure.
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The anatomical
snuffbox is the triangular area on the
back of the hand at the base of the thumb. When the thumb
is extended this area appears as a small depression and
is encircled by the tendons of the long and short extensor
muscles of the thumb.
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No man’s
land (zone II) is the zone in the palmar
or volar surface of the hand between the distal palmar
crease (the crease closest to the fingers) and the middle
of the middle phalanx (middle finger).
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The thenar
eminence is the prominent pad formed by
the muscles below the thumb on the palmar (volar) side
of the hand.
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The hypothenar
eminence is the smaller pad on the ulnar
side of the palm formed by the muscles of little the finger.
Ganglion cysts
are the most common mass in the hand. They occur most frequently
on the volar and dorsal surfaces of the wrist, in the palm
at the base of a finger (flexor tendon sheath cyst), and on
the dorsal surface of the distal interphalangeal joint (DIP)
near the base of the fingernail (mucous cyst). These fluid-filled
cysts arise from the ligaments, synovial joint linings, or
tendon sheaths when they are irritated or inflamed. They may
be hard or soft, may or may not be painful, and may disappear
or change size quickly.
Boutonniere deformity
refers to a finger that is bent down at the PIP joint and
bent back at the DIP joint. This deformity is usually due
to an injury, although it can develop in inflammatory disorders
such as rheumatoid arthritis. Some people are born with a
mild boutonniere posture of most or all of their fingers.
The tendons that straighten these finger joints are a complicated
network of strings running from the sides and back of the
finger to a sheet of tissue (the central slip of tendon) on
the top of the finger. When the finger is hit or bent forcefully,
the sheet tears away from its attachment to the top of the
middle phalanx of the finger. The tear in the tendon sheet
looks like a buttonhole ("boutonniere" in French),
and the end of the phalanx actually begins to stick through
the hole. As a result, the tendons can't straighten the middle
joint (which stays bent) and all of the force of the tendons
bypasses the PIP joint and goes to the DIP joint which flips
backward. The problem can also result from a laceration on
the back of the finger.
Carpal tunnel syndrome
(median neuropathy) results from pressure on the median nerve.
The nerve passes through a protective tunnel on the volar
aspect of the wrist along with the nine tendons that bend
the fingers. This tunnel is just wide enough to hold all these
structures. The median nerve provides sensation to the thumb,
index, middle, and ring fingers and supplies muscle function
to the thenar muscles at the base of the thumb. When the tendons
are irritated, their synovial linings swell and place pressure
on the median nerve, cutting off its blood supply. Carpal
tunnel syndrome causes a variety of problems, including pain,
tingling, numbness, swelling, and weakness of the thumb, index,
middle, and ring fingers. Common causes and associated conditions
that may aggravate tendon swelling include repetitive grasping,
repetitive bending of the wrist, broken or dislocated bones
in the wrist, rheumatoid arthritis, thyroid gland imbalance,
diabetes mellitus, pregnancy, and menopause.
Kienbock's disease
is believed to result from interruption of blood supply to
the lunate bone with subsequent avascular necrosis of the
bone. Certain people are prone to this condition if the ulna
is shorter than the radius or if an inadequate number of blood
vessels exists to nourish the lunate. This situation may be
present in both wrists. Kienbock's disease is staged from
grade I to grade IV depending upon the severity of the problem.
Basal joint arthritis
occurs at the carpometacarpal joint at the base of the thumb.
Because of its design, the CMC joint tends to wear out and
develop arthritis early in life. It causes pain at the base
of the thumb, particularly during pinching or gripping. Many
people appear to be predisposed to arthritis in this joint,
with or without arthritis in other joints. As the joint deteriorates,
small bone spurs called Heberden nodes form over it and make
the back of the hand appear "lumpy."
Stenosing tenosynovitis
is an inflammation of the synovial linings of the tendons
in the hand. Six separate compartments on the back of the
hand house the abductor and extensor tendons to the digits.
Each compartment is lined with a synovial sheath membrane
similar to the synovial lining of joints. The tendons must
pass through a narrow tunnel enclosed by bone and ligament.
Repetitive movement of the digits or wrist may cause increased
friction within this tight space, causing the tenosynovial
lining of the tendons to produce excessive lubrication (synovial
fluid). Over time, the tendon becomes inflamed and increases
in size, causing pressure within this tight space and ultimately
producing pain. The most common types of stenosing tenosynovitis
are:
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DeQuervain's
tenosynovitis is an inflammation of the
extensor pollicis brevis and abductor pollicis longus
tendons due to compression by the two bony prominences
of the distal radius, just proximal to the anatomic snuffbox.
DeQuervain’s disease causes wrist and forearm pain
as these tendons work to move the thumb away from the
palm. The condition is most common in adult women between
the ages of 30 and 50.
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Intersection
syndrome occurs in the second dorsal compartment
of the extensor carpi radialis brevis and extensor carpi
radialis longus tendons where these tendons cross under
the abductor pollicis longus and the extensor pollicis
brevis.
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Trigger finger
or trigger thumb is an irritation of the digital flexor
tendon sheath. When the tendon sheath becomes thickened
or swollen it pinches the tendon and prevents it from
gliding smoothly. In some cases the tendon catches and
then suddenly releases as though a "trigger"
were released.
Dupuytren's contracture
is a progressive thickening and contracture of the skin and
fascial tissues of the palm. The condition causes pain, progressive
joint contracture, and inability to lay the hand flat.
Volkmann's contracture
is a flexion deformity of the wrist associated with hyperextension
of the fingers. This condition may be due to a compartment
syndrome following trauma to the forearm or due to ischemia
in the distribution of the brachial artery following a displaced
fracture of the humerus.
Boxer's fracture
is the common name for a break in the end of the small finger
metacarpal bone. It is usually caused by punching a hard object.
The end of the metacarpal bone takes the brunt of the impact
and usually breaks through the narrowest area near the neck,
bending down toward the palm.
Gamekeeper’s thumb
is a specific type of injury of the joint where the thumb
joins the palm on the index finger side of the thumb. The
injury usually occurs when the thumb becomes caught on the
way down during a fall. If the thumb is pushed sideways away
from the index finger, the ligament connection between the
bones may be torn. Usually, just the ligament is torn, but
a small chip of bone may be torn off as well. The ligament
is normally covered by a sheet of fascial tissue. Sometime,
when the ligament tears, a hole tears in the fascia as well.
The end of the ligament herniates through the hole and becomes
trapped. The thumb may lose strength, and the abnormal side-to-side
movement of this floppy joint may lead to a permanent bend
in the joint, arthritis, or both.
Mallet finger injury
usually represents mechanical failure of the terminal digital
extensor tendon, either from tendon disruption or fracture.
Mallet injuries are staged I through IV depending upon severity
of the injury.
Flexor tendon injuries
generally occur as the result of a cut. The flexors lie just
beneath the skin at each of the folds on the palmar surface
of the fingers. Tendons are easily injured at these sites
even by a shallow laceration. The location of the tendon injury
greatly influences the degree of recovery after surgery. Cuts
in the fingers do not do as well as those in the forearm.
"No man’s land" is the area in the hand and
fingers where healing is most difficult. Postoperative stiffness
of the joints and limited tendon motion are common problems
with injuries in this area. After a flexor tendon injury,
most people lose some movement in the finger, despite all
treatment efforts.
Open fractures
of hand bones occur as the result of trauma. In an open fracture,
the broken bone penetrates through the skin. If portions of
the fingertip are missing, the injury is usually described
as a partial amputation. Amputations that involve the tuft
of the distal phalanx are open distal phalangeal fractures.
This type of fingertip wound is the most common injury seen
in hospital emergency departments.
Osteoarthritis
is a progressive disease that occurs over time due to the
"wear and tear" of joint surfaces caused by motion.
Once the process of arthritis has begun, the natural history
is erratic progression of joint deterioration. The condition
commonly results in pain, deformity, joint enlargement, instability,
stiffness and loss of function. Symptoms are often episodic,
but may be constant.
Rheumatoid arthritis
is the most common disorder of connective tissue with an incidence
of 1-3% of the population. It is three times more common in
women than in men. The principal target tissue is the synovium
that lines joints and tendons. Over 90% of affected patients
have involvement of the upper limb. The disease causes destruction
of the smooth gliding joint surfaces. Invasion of the underlying
bone causes collapse and distortion of the joint surfaces.
The synovium may also invade the surrounding joint capsule
and ligaments, weakening them and causing deformity and joint
instability. The same inflammatory process can occur in synovial
tendon linings. If tendons become inflamed, joint motion is
inhibited and ultimately results in malalignment or rupture
of the involved tendons. Swollen tendons may also place pressure
on nearby nerves, causing neuralgia and paresthesias.
Fasciotomy
is simple surgical correction of a flexion contracture. The
physician makes a stab wound in the palm and incises the fascia
to relax the flexed position of the fingers. The procedure
may be done under local anesthesia and is usually reserved
for elderly patients who are not suitable for more complicated
surgery.
Fasciectomy
is another surgical technique to release flexion contractures.
The surgeon incises the palmar fascia and resects all hypertrophied
fascial tissue. The flexor tendon sheaths are freed and the
wound is closed in layers using a Z-plasty technique to lengthen
the tissues and prevent recontracture. Skin grafting is used
as necessary to prevent placing tension on the closure. Occasionally,
a segment of the wound is left open to heal by itself (open-palm
technique).
Dermofasciectomy
is done in cases of Dupuytren's disease if it is necessary
to remove the overlying skin as well as the fascia at the
contracture site. This procedure is indicated if skin is stuck
to the fascial bands and cannot be moved over them, when the
contracture has recurred after prior surgery, or in young
patients who generally have more aggressive disease. Dermofasciectomy
requires extensive skin grafting.
Tendon reconstruction:
The ends of lacerated tendons can be joined and stitched successfully,
usually within the first month after injury. If the primary
repair fails or tendon injury is recognized too late, simple
suturing is no longer a surgical option. Tendon ends retract
and shorten after injury and adhesions to the tendon sheath
with sheath narrowing often develop. In these cases, tendon
reconstruction is required. The procedure requires two staged
operations. In stage I, the surgeon makes a long zigzag incision
from fingertip to palm. The damaged tendon is removed and
a soft silicone rod is passed along the length of the sheath.
This rod remains in place for about ten weeks. During this
time, a new lining forms around the rod. This lining will
both nourish and allow movement of the tendon graft. In stage
II, a piece of tendon is harvested from either the wrist or
leg. Only the ends of the previous long scar on the hand are
opened. The tendon graft is joined to the silastic rod and
then drawn through the new lining as the rod is removed. The
graft is then attached to the two ends of the old tendon and
the tension adjusted to allow the finger to work properly.
The repair at the end of the finger is performed either with
a stitch through the bone or the tendon is taken through the
tip of the finger. In either case, the repair is stitched
to the nail.
CMC joint reconstruction:
Several different operations may be done for CMC joint arthritis.
Total joint reconstruction is one of the most common operations
and is done in three main steps. First, the trapezium bone
at the base of the thumb is removed. Next, a tendon graft
is constructed to connect the adjacent sides of the base of
the thumb and index finger. This graft maintains thumb position.
Finally, a cushion is constructed to pad the space between
the bones where the trapezium bone used to be. This cushion
is usually also made from a tendon graft so that the base
of the thumb rests on a pillow of soft tissue rather than
on the rough surface of an arthritic bone. The bones may be
held in place with a temporary steel pin.
Arthrodesis
is the surgical fixation of a joint to prevent motion. It
may be performed with internal or external fixation and with
or without a bone graft. The surgeon incises the skin and
dissects all joint surfaces with a burr or saw. The joint
may then be fixed with wire, screws, or plates. If a bone
graft is used, bone is harvested either from the iliac crest
or the distal radius. Harvested bone is packed down into the
joint site to promote fusion of the bone ends, and the joint
is fixed with a K-wire until completely healed. Common sites
for arthrodesis in the hand are the carpal joints and the
MCP joint of the thumb.
Arthroplasty
(joint replacement) involves removal of a damaged joint and
replacement with an artificial joint made of silicone rubber.
MCP joint replacement is most commonly undertaken for advanced
rheumatoid arthritis. The Swanson silastic implant is the
most common prosthesis used. The implant acts as a flexible
hinge. Because of its structure it does not accurately replicate
the biomechanics of the joint it replaces, and so full function
is never restored. Most surgeons use it almost exclusively
in the low demand hands of rheumatoid arthritis patients.
Carpal tunnel
release is done to provide more space for the nerve and tendons
so that swelling will not put undue amounts of pressure on
the nerve. It may be performed as an open or endoscopic procedure.
The open procedure involves creation of a 5 to 6 centimeter
incision at the base of the palm. The transverse carpal ligament
is divided to expose the contents of the canal. The area is
explored and the nerve is inspected. Inflamed flexor tenosynovium
is resected as necessary, the skin is sutured, and a splint
is placed.
The endoscopic procedure involves either one or two small
incisions to allow insertion of an arthroscope. The undersurface
of the transverse carpal ligament is visualized and additional
instruments are used to divide the ligament in order to relieve
pressure on the nerve. Sutures are placed and a dressing is
added.
Proximal row carpectomy (PRC)
is done for localized arthritis and involves removal of the
first four carpal bones and the creation of a new joint between
the capitate and radius. Tendons, nerves and blood vessels
are carefully preserved during excision, and ligaments are
usually reattached to secure the newly formed joint.
Bone graft with microvascular
anastamosis: Vascularized bone grafts are
used in cases where large bony defects exist. Examples of
clinical indications for this procedure include gunshot blast
wounds of the hand and bone loss due to osteomyelitis or bony
tumor resection. In the hand, the bones most often replaced
are the metacarpals. The surgeon harvests vascularized bone,
usually the metatarsals, and transfers them to the hand. Tendons,
nerves, and vascular anastamoses are performed with the use
of an operating microscope.
Great toe-to-hand wrap around
transfer with microvascular anastamosis: In
cases of thumb amputation, a great-toe-to-hand transfer procedure
offers patients the best chance for restoration of both mechanical
and sensory function. To begin the procedure, the surgeon
harvests a segment of the iliac crest and sculpts it to replace
the amputated proximal and distal phalanges of the thumb.
The microvascular aspect of the procedure includes transferring
the skin, nerves, vasculature, and nail from the toe and literally
wrapping this tissue around the iliac bone graft that has
been fixed onto the residual first metacarpal. This procedure
creates a new thumb that looks more like a thumb than a great
toe transfer. A skin graft is sometimes needed to close the
great toe donor site.
Open traumatic wounds of the hand require careful assessment
to determine the best method of treatment and wound closure.
Factors considered in determining the best wound closure technique
are the degree and type of wound contamination, the time elapsed
since injury, and adequacy of debridement and decontamination.
Debridement
of open hand wounds is performed to reduce the potential for
complications that may jeopardize the viability of the digits
or hand. The protocol includes cultures, antibiotic administration,
irrigation, and removal of debris and devitalized tissue.
Debridement may include removal of skin, subcutaneous tissue,
muscle, fascia, bone, and foreign bodies. In some instances,
jets of water and meticulous irrigation and scrubbing may
sufficiently debride the wound site. In larger, more contaminated
wounds, a scalpel, scissors, curettes, and bone rasps are
used to perform the procedure.
Primary closure
means suturing an open wound within 24 hours of injury. Indications
for primary closure include clean incisions, little or no
contamination, little or no soft tissue damage, and a wound
that occurred less than 8 hours prior to treatment. Crush
injuries, gunshot wounds, and bites are examples of wounds
that are not primarily closed.
Delayed primary closure
is done between the 2nd and 7th days post injury. This method
is used when the physician needs to take a "second look"
at an injury to perform additional debridement, reassess infection
status, etc.
Secondary closure
of a wound is done after the 7th day following injury. It
is used for more severe, untidy wounds, especially if there
is some crushing of soft tissues involved. Secondary closure
often involves skin grafts or pedicle transfers.
Nonclosure
is a treatment alternative in which the wound is left open
and allowed to heal by "secondary intention." Transverse
wounds along the volar aspect of the palm and fingers are
frequently debrided, dressed, immobilized, and allowed to
heal in this way.
Practice Makes Perfect!
Are you ready for some hands-on practice?
Read the patient report(s) on our procedure
practice page. Assign the appropriate codes and
then compare your answers with our coding
recommendations. Good luck!
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and Injuries - Surgical
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Closure Techniques for Traumatic
Hand Wounds
If you have comments or suggestions about our code selections
or about any topic on our Coding Edge® pages, please e-mail
us at codingedge@lagunamedsys.com.
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