Physical exam of the hand

Question 1

It takes 2 months for a complete nail plate to grow. True or false?

Answer 1

False. Nail plate growth is highly variable among individuals and may be modified by numerous factors. However,
it takes approximately 6 months for a complete nail plate to grow. At 2 months after avulsion, the nail plate is visible
only at the level of the proximal nail fold.

Question 2

Is it useful to have a proximal nail fold?

Answer 2

Kligman’s experiences have shown that the nail matrix is responsible for almost all production of the nail plate but is
unable to control its shape. The proximodistal growth of the nail plate is, in part, controlled by the proximal nail fold,
which limits the growth in height and forces the nail plate to grow distally. The proximal nail fold is also useful to protect
the nail plate, which, at this level of the finger, is thin, fragile, and poorly adherent to the matrix.

Question 3

What is the Hutchinson’s sign? What does it mean?

Answer 3

Hutchinson’s sign is a dark discoloration of the nail plate and the proximal or distal nail fold. It is highly suggestive
of a subungual melanoma

Question 4

What is the function of nails?

Answer 4

Early medical descriptions state that nails were made for scratching, especially of the small animals that live on our
body. Science has since shown that this is not their only function. Nails contribute to thermoregulation because of
their richness in neurovascular glomi. Their main function is to serve as a counterpressure for the pulp that enhances
discrimination. Patients without nails are unable to button their shirt. Nails also serve to pick up small objects and
protect against trauma. Finally, nails have a cosmetic function. Because nails are so useful, maybe you should stop
biting them before exams.

Question 5

What is the best test to appreciate the functional sensibility of the hand?

Answer 5

Many sensory tests have been described, but most of them are useful only to appreciate central or medullar
neurologic lesions. To pick up and hold small objects correctly, the hand must be able to discriminate and to
recognize various forms or textures. The best way to appreciate the functional sensibility of the hand is to test its
discrimination.

Question 6

How can you appreciate the sensory discrimination of a finger pulp?

Answer 6

By using the two-point discrimination test described by Weber. The points of calipers are held against the skin at
different distances from each other. The test determines the minimal distance at which the patient can distinguish
whether one or two points are in contact with the skin. The patient must be comfortable, and the examiner must avoid
pushing against the calipers with his/her fingers, thereby artificially increasing the pressure. The higher the pressure,
the wider the area of skin that is deformed and stimulated. One or two points are touched in a random sequence along a
longitudinal axis in the center of the finger tip. The American Society for Surgery of the Hand recommends seven correct
answers out of 10 for two-point discrimination.

Question 7

What is the normal value for the two-point discrimination test at the pulp
of the finger?

Answer 7

between 2 and 3 mm at the pulp
of the finger. In patients employed in heavy labor, normal values are closer to 5 or 6 mm. In patients with congenital or
acquired blindness, it may be as low as 1 to 2 mm.

Question 8

Why do patients with a low ulnar nerve palsy often have permanent abduction of the
small finger? What is the name of this deformity?

Answer 8

This acquired deformity is known as Wartenberg’s sign. Blacker et al. showed that the extensor digiti minimi
tendon has two bundles. The radialmost tendon passes over the center of the axis of abduction–adduction of the
metacarpophalangeal (MP) joint or slightly radial to it. The ulnar tendon, which is the thicker of the two, passes ulnar to the axis in most patients and gains a firm attachment to the tendon of the abductor digiti quinti. By means of these slips,
the extensor digiti minimi has acquired a bony attachment to the tubercle of the proximal phalanx. The extensor digiti
minimi thus has the potential to abduct the little finger through this indirect insertion.

Question 9

How do you test the flexor digitorum profundus tendons?

Answer 9

Tendons of the flexor digitorum profundus (FDP) insert on the volar aspect of the distal phalanx of the fingers. The FDP
tendon is the only tendon that allows flexion of the distal phalanx onto the middle phalanx. To test this tendon, the
examiner should immobilize the proximal interphalangeal (PIP) joint in complete extension and ask the patient to flex the
distal phalanx. In patients with limited strength or mobility, it is easier to appreciate even a small amount of motion if
you place the wrist and MP joint in complete extension (Fig. 115-1)

Question 10

How do you test the flexor digitorum superficialis tendons of the fingers?

Answer 10

Tendons of the flexor digitorum superficialis (FDS) insert on the volar aspect of the middle phalanx and flex the middle
phalanx on the proximal phalanx. However, to examine the FDS tendon, it is mandatory to block the action of the FDP
tendon, which is also able to flex the PIP joint after flexing the distal interphalangeal (DIP) joint. To block the FDP, the
tendons of which arise from a common muscle belly, you need only to block the DIP joint of two or three fingers in
extension. In doing so, you prevent the action of the FDP on the finger you wish to test. You obtain only flexion of the
middle phalanx on the proximal phalanx without flexion of the DIP joint. During flexion of the PIP joint, the extensor
mechanism glides distally. Patients are unable to control the motion of the distal phalanx from this position. This
phenomenon, known as the “floating” distal phalanx, does not always hold true for the index finger, in which the FDP
muscle belly is often independent of the three ulnar fingers (Fig. 115-2).

Question 11

If I try to test the FDS of the little finger as described in Question 10, why does the
patient flex only the MP joint and not the PIP joint?

Answer 11

** Approximately 15% of people do not have an FDS tendon for the little finger.
** Another group of people (also approximately 15%) has a tendon that is not functional.
** Some people have an FDS tendon for the little finger that is functional but highly adherent to the FDS tendon of the
ring finger, which is maintained in extension. If you allow the PIP joint of the ring finger to flex, the patient will flex the
PIP joint of the little finger. MP joint flexion of the little finger is provided by the flexor digiti quinti and the abductor
digiti minimi.

Question 12

How can you determine whether there is an FDS in the index finger if the FDP of the
index is independent?

Answer 12

There is only one test to determine whether the FDS of the index finger is present. Ask the patient to hold a sheet
of paper between the pulp of the thumb and index. The examiner pulls on the paper while the patient tries to resist.
Because flexion strength is provided by the FDS, in a normal finger the digit will be slightly flexed at the PIP joint and
extended at the DIP joint as in a “pseudo-boutonnière” deformity. In a patient without an FDS tendon, the DIP joint will
flex to resist the traction and the PIP joint will stay in extension in a “pseudomallet” deformity.

Question 13

In patients with rheumatoid arthritis who are unable to extend the ulnar three digits,
what are the possible diagnoses?

Answer 13

** Rupture of the extensor tendons must be suspected. Extensor tendons usually rupture after attrition on a dorsally
subluxated ulnar head. In such cases, if you ask patients to extend the fingers, you will see no bowstringing of the
extensor tendons beneath the skin.
** In patients with ulnar deviation of the fingers, extensor tendons may dislocate in the intermetacarpal valleys. In such
cases, if the MP joints are not stiff, passive extension of the fingers will allow patients to maintain the extension.
** The rarest cause is compression of the posterior interosseous nerve at the elbow. Usually in such cases, extension is
weak but still possible, and wrist flexion will draw the fingers into extension as a result of the tenodesis effect.

Question 14

How can you determine that the extensor pollicis longus tendon is intact and functional?

Answer 14

The extensor pollicis longus (EPL) tendon inserts on the dorsum of the distal phalanx of the thumb and is responsible for
active extension of the distal phalanx. In most patients, its rupture leads to a flexion deformity of the IP joint and inability
to extend the distal phalanx actively. However, extension of the intrinsic muscles of the thumb and adhesions between
the EPL tendon and the extensor pollicis brevis (EPB) tendon give some patients the ability to achieve complete active
extension of the IP joint even if the EPL tendon is ruptured. To be sure that the EPL tendon is intact, ask the patient to
place his/her hand flat on a table. Then ask the patient to raise the thumb off the table (retropulsion). The EPL muscle
is the only muscle responsible for this movement. You can also see and palpate the bowstringing of the tendon beneath
the skin. Rupture of the EPL tendon was first described in drum players of the Prussian army, but you will probably see it
more often in patients with Colles’ fractures.

Question 15

If flexion of the MP joint is limited, how can you determine whether the extensor
tendons are adherent at the dorsum of the hand or at the wrist level?

Answer 15

By using the tenodesis effect. As most tendons cross several joints, it is possible to contract or relax them by changing
the position of these joints. In the case of adhesion at the wrist level, wrist extension adds some flexion at the MP joint,
whereas MP joint flexion does not change if the adhesion is located on the dorsum of the hand. This test is valid only if
there is no ligamentous retraction at the MP joint.

Question 16

What is Allen’s test? How do you perform it?

Answer 16

Allen’s test evaluates the patency of the radial and ulnar arteries at the level of the wrist. The patient is asked to raise
and clench his/her hand to exsanguinate the cutaneous vascular bed. The examiner compresses the radial artery in
the radial groove and the ulnar artery in Guyon’s canal. The patient opens the hand without hyperextending the fingers.
The palm appears pallid. The examiner releases one compressed artery and notes the time required for the palm to
recover its normal color. The maneuver is repeated to evaluate the other artery.

Question 17

How do you determine a rotational deformity of the finger: in flexion or in extension?

Answer 17

In flexion. The only way to determine a rotational deformity is to ask the patient to flex his/her fingers. Because of the
orientation of the MP and PIP joints, all of the fingers converge in flexion toward the scaphoid tubercle. Thus even a
minor rotational deformity that may not be apparent in extension becomes obvious (Fig. 115-3).

Question 18

Why is DIP joint flexion more important when the PIP joint is flexed than when the
PIP joint is extended?

Answer 18

PIP joint is extended?
This clinical test is called the Haines-Zancolli test (Fig. 115-4). Limited flexion of the DIP joint, when the PIP joint is
maintained in extension, is due to the retaining action of the oblique retinacular (Landsmeer’s) ligament. Landsmeer’s ligament inserts on the proximal phalanx and digital sheath, volar to the axis of flexion–extension of the PIP joint. It
ends on the extensor tendon, dorsal to the axis of flexion–extension of the DIP joint. As a result, there is more stress
on Landsmeer’s ligament in extension of the PIP joint than in flexion; thus DIP joint flexion is easier with the PIP joint in
flexion than in extension. Landsmeer’s ligament coordinates the movement of the IP joints. It is placed under tension by
flexion of the DIP joint, which causes simultaneous flexion of the PIP joint. The ligament is also placed under tension by
extension of the PIP joint, which in turn causes extension of the DIP joint. Contraction of the oblique retinacular ligament
has been described in the boutonnière deformity and Dupuytren’s disease.

Question 19

In patients experiencing stiffness with extension of the PIP joint, which clinical test
identifies contracture of the interosseous muscles?

Answer 19

The Finochietto-Bunnell test (Fig. 115-5). When the MP joint is in extension, the contracted interosseous muscles impede
flexion of the PIP joint because of the traction exerted on the extensors. Flexion of the MP joint relaxes the extensors,
and flexion becomes possible at the PIP joints.

Question 20

Which clinical test is specific for de Quervain’s tenosynovitis? How is it performed?

Answer 20

Finkelstein’s test (Fig. 115-6). De Quervain’s tenosynovitis affects the first dorsal extensor compartment as its contents
(abductor pollicis longus [APL] and EPB tendons) pass over the radial styloid. Ask the patient to flex the thumb into the palm and to maintain it with the other fingers. The wrist is then placed in ulnar deviation, which causes a sharp pain at
the radial styloid due to tension on the APL and EPB tendons.

Question 21

Which clinical signs are suggestive of flexor carpi radialis tendinitis?

Answer 21

Flexor carpi radialis (FCR) tendinitis is not a rare disease. As in most cases of tendinitis, pain is the most frequent
complaint and is increased by resisted active contraction and passive stretching of the muscle–tendon unit. In FCR
tendinitis, pain is localized on the volar aspect of the wrist and frequently radiates to the forearm. Pain is increased
by resisted wrist flexion and passive extension of the wrist. Swelling is sometimes present along the tendon of the FCR
and must be differentiated from a wrist ganglion. Some patients complain of diffuse pain and paresthesias on the base of
the thenar eminence secondary to irritation of the palmar cutaneous branch of the median nerve

Question 22

If the IP joint of the thumb is flexed, why does the DIP joint of the index finger flex
simultaneously?

Answer 22

This anatomic variation, known as Linburg’s sign, is present in approximately 30% of people. It is due to adhesions in
the carpal tunnel between the flexor pollicis longus and FDP tendons of the index finger. Flexion of the thumb sometimes
causes other fingers to flex. This variation usually causes no functional impairment but has been described as a source
of problems in some musicians who lack independence of the fingers.

Question 23

In a patient who has sprained an MP joint, how can you diagnose a ligamentous
rupture with instability?

Answer 23

To appreciate instability you must apply stress to the collateral ligament in adduction or abduction. However,
abduction–
adduction laxity of the MP joint in extension is normal because the collateral ligaments are not under
tension. If you place the MP joint in complete passive flexion, because of their eccentric insertion and the shape of the
metacarpal head, the collateral ligaments will be under tension without laxity in either abduction or adduction in normal
patients. Then it is easy to appreciate abnormal laxity in patients with ligamentous ruptures.

Question 24

What are the etiologies of a swan neck deformity of the fingers?

Answer 24

In swan neck deformity, the PIP joint is in extension and the DIP joint in flexion. Swan neck deformity is due to excessive
traction by the extensor apparatus inserted on the base of the middle phalanx and is favored by laxity of the PIP joint
(Table 115-1)