W
ithout the human hand, the most refined creationsof the human mind would be mere theoretical concepts. The hand is the focal point of human beings' interactions with the environment; it is the instrument used to deliver a knockout punch or to perform brain surgery. The hand is an organ of such complexity that many devote their lives to studying it and curing its ills.
The varied functions of the hand include grasping, pinching, and acting as a hook or paperweight. About 4 5 % of the work of the hand utilizes grasp, a power func- tion that requires coordinated action of both the intrinsic hand muscles and the extrinsic thumb and finger flexors. Variations of the grasp mechanism allow a person to make a tight fist or to securely hold an object such as a ball or glass (Fig. 4-1A). Another 45% of hand function utilizes pinch. Varieties of pinch include side pinch (key
pinch), between the tip of the thumb and the side of the
index finger (Fig. 4-1B); tip pinch, between the tip of the
rotated thumb and the tip of another finger (Fig. 4-1C);
and chuck pinch, which requires opposition of the
thumb to form a triangular chuck with the tips of the long and ringfingers (Fig. 4-1D). About 5% of the hand's
activities require functioning as a hook. This more primi- tive function allows the curved fingers to span handles or support thin objects (Fig. 4 - l E ) . In the remaining 5% of tasks, the hand functions as a paperweight (Fig. 4 - l F ) . This most primitive of hand functions does not require the intrinsic strength or fine manipulative abilities neces- sary for more delicate tasks. Chronic pain prevents any
useful task.
The hand functions well because it is suspended at the end of the arm. The shoulder and elbow serve to position the hand in space, allowing it to perform the precise functions required. Before c o m m e n c i n g a detailed examination of the hand and the wrist, the examiner must perform a general assessment of the shoulder, elbow, and forearm. This may be done rapidly by asking the patient to raise the hands overhead until the arms touch the cars, to bring the arms down by the
sides, to place the hands behind the head, to place the hands behind the back, to place the arms at the sides with the elbows flexed to 90°, then to fully pronate and supinate the forearms, to flex the elbows fully, and to extend the elbows fully. This sequence gives the examiner a brief overview of the range of motion of the other joints of the upper extremity and allows the examiner to screen for any gross abnormality that might secondarily affect hand and wrist function.
• INSPECTION
Surface Anatomy
For comfort and convenience, the hand and wrist are usually inspected with the patient and physician seated facing each other. The hands may be rested on a small table or desk, on a pillow resting on the patient's lap, or on the lap itself. With the hands extended in front of the patient and the forearms pronated, the forearm, hand, and extended fingers should form a straight line. Any break in that line is abnormal and requires further inves- tigation.
ORIENTATION
When describing locations in the hand and wrist, the tra- ditional terms anterior, posterior, medial, and lateral are usually replaced by the terms volar (palmar), dorsal,
ulnar, and radial. The ability of the forearm to rotate
changes the position of structures in the distal forearm and hand in relation to the rest of the human body; it is thus less confusing to describe them in relationship to surfaces within the hand and wrist. Thus, dorsal refers to the back of the hand and wrist; volar or palmar refer to the anterior surface of the hand and wrist, including the palm; radial refers to the side of the hand and wrist on which the t h u m b and radius are located; and ulnar refers to the side of the hand and wrist on which the little finger and ulna are located.
101
1 0 2 CHAPTER 4 H a n d a n d Wrist
Figure 4 - 1 . Functions of the hand. A, Grasp. B, Side pinch (key pinch). C, Tip pinch. D, Chuck pinch. E, Hook. F, Paperweight.
Figure 4-2. A, C, and D, Dorsal aspect of the hand. A, fingernail; B, cuticle; C, distal interphalangeal joint; D, proximal
inter phalangeal joint; E, metacarpophalangeal joint; F, web space; G, distal phalanx; H. middle phalanx; I, proximal phalanx; /, metacarpal; K, first dorsal interosseous; L, extensor tendon (index finger). B, close up of thumb.
104 CHAPTER 4 Hand and Wrist
Figure 4-3. Paronychia (arrow).
DORSAL ASPECT
The dorsal aspect of the hand and wrist is inspected with the patient's forearm pronated.
Fingernails. Closest to the examiner are the fingernails, which protect the dorsal tips of the digits and assist in picking up fine objects. (Fig. 4—2). A smooth epony- chium, or cuticle, surrounds the base of the nail. Ideally, the nail itself should be smooth and oval. The nailbed itself, visible through the nail, should be a healthy pink, with the exception of a small white crescent or lunula at the base of some nails. The color of a nail reflects the cir- culatory status of that particular digit; the color of the nails as a whole may reflect the circulatory status of the hand and the cardiovascular function of the patient.
Deformities of the nail are legion and may reflect injury to the nailbed or systemic disease. C o m m o n nail deformities include splitting owing to a previously lacer-
Figure 4-4. Subungual hematoma.
ated nailbed and pitting owing to psoriatic arthritis. Fungal nail infections, more common in the foot, may also leave the fingernails thickened and deformed. The appearance of the nails may reflect not only the patient's health status but his or her occupation and personality as well. Swelling around the base of the fingernail, often asymmetric and accompanied by erythema, many times reflects an infection known as a paronychia (Fig. 4 - 3 ) . Maroon discoloration at the base of the nail usually reflects a subungual hematoma, which often results from a direct blow to the fingertip. (Fig. 4-4) Subungual hematoma m a y b e associated with an underlying fracture of the distal phalanx.
Digits. The digits themselves should appear straight, with
transverse wrinkles marking the locations of two inter- phalangeal joints. The t h u m b is composed of proximal and distal phalanges linked by an interphalangeal joint. Localized swelling may reflect a specific injury or a more systemic disease process. Multiple bony nodules around the distal interphalangeal (DIP) joints are known as
Heberden's nodes (Fig. 4-5) and are typical of
osteoarthritis. A mucous cyst is a cystic lesion on the dor- sum of the finger arising from the DIP joint and may deform the fingernail (Fig. 4-6). It is associated with degenerative arthritis of the DIP joint and arises from the joint itself.
Degenerative changes in the proximal interpha-
langeal (PIP) joints may also occur in osteoarthritis.
These firm, bony nodules are known as Bouchard's nodes (Fig. 4—7). When these joints are involved with rheumatoid arthritis, there are no nodes but the joint
Figure 4-6. Mucous cyst
swelling is soft and puffy. The PIP joints are also common sites of dislocations and collateral ligament sprains. These injuries produce localized swelling and a visible step-off if a nonreduced dislocation is present.
Fractures may occur in any of the phalanges. They are marked by localized ecchymosis and fusiform swelling. Angular or rotational deformities may also be present. More complex deformities of the fingers are dis- cussed under Alignment.
The webbing at the base of the finger slants distally from the dorsal toward the volar side of the hand. The distal limit of the web spaces between the fingers actually marks the midpoint of the proximal phalanges. The
metacarpophalangeal (MCP) joints are usually subtly visible as a series of bumps in line with the fingers. Swelling around one of these joints following trauma usually reflects a fracture, sprain, or dislocation. Inflammatory swelling of the metacarpophalangeal joints is commonly found in rheumatoid arthritis.
Hand. The dorsal skin of the hand is normally loose and
redundant (Fig. 4-8). This allows for flexion of the fin- gers. Chronic swelling from edema will block full flexion. The extensor tendons to the four fingers are usually visi- ble as they cross the metacarpophalangeal joints. Asking the patient to forcefully hyperextend the fingers usually increases the prominence of the extensor tendons (Fig. 4-9). C o m m o n causes of swelling over the dorsum of the hand include metacarpal fracture, hematoma, and inflammatory tenosynovitis. Because the metacarpals are subcutaneous, angulation associated with fractures of their shafts is usually visible once the initial swelling has declined. Fracture of the metacarpal shaft just proximal to the metacarpophalangeal joint is particularly common in the fifth metacarpal, where it is known as a boxer's frac-
ture. Such fractures often produce a dropped knuckle;
the metacarpal head is depressed and its normal promi- nence disappears. Carpal bossing is the term for benign bony prominences that can form on the dorsum of the proximal ends of the second and third metacarpals.
The first dorsal interosseous is the most prominent muscle mass of the dorsum of the hand. Located along the radial border of the second metacarpal, the first dor- sal interosseous creates a large fleshy prominence between this metacarpal and the thumb. Visible atrophy of the first dorsal interosseous is associated with severe degrees of ulnar neuropathy, loss of ulnar nerve function. In the presence of severe ulnar neuropathy, the conse- quent atrophy of the ulnar innervated interosseous mus- cles makes the metacarpal shafts more visible.
106 CHAPTER 4 Hand and Wrist
Figure 4-8. Looseness of dorsal skin.
Wrist. The b u m p caused by the head of the distal ulna is the most prominent bony landmark of the dorsal wrist (Fig. 4-10). Just distal to the head of the ulna is a small hollow marking the location of the triangular fibrocarti- lage complex (TFCC). The extensor carpi ulnaris ten- don passes over the ulnar aspect of the pronated ulna and may occasionally be visible just distal to the wrist, espe- cially if the wrist is actively extended and ulnar-deviated. The tendons of the extensors carpi radialis longus and brevis are more apt to be visible in wrist extension, as
they cross the wrist to insert at the base of the second and third metacarpals. Again, asking the patient to dorsiflex or extend the wrist actively increases the prominence of these tendons. Active extension of the thumb also makes the tendon of the extensor pollicis longus quite visible (Fig. 4-11). This tendon enters the wrist from the center of the distal forearm, where it makes a sharply angled turn at the prominence of the radius known as Lister's tubercle, en route to its insertion at the base of the thumb. Because of the angle of approach that the EPL. tendon makes with the thumb, this tendon supinates and adducts the t h u m b as well as extends it. Lister's tubercle is a common site for rupture of the tendon following frac- ture of the distal radius or rheumatoid synovitis. In the case of such a rupture, the normal prominence of the ten- don disappears.
Diffuse swelling over the dorsum of the wrist is com- mon in rheumatoid arthritis or from hemorrhage follow- ing fracture of one of the carpal bones or injury to the intercarpal ligaments (Fig. 4-12A). The swelling due to synovitis is more diffuse and extends further distally over the dorsum of the hand compared with the hematoma associated with a fracture or a ligament injury. Fracture of the distal radius is extremely c o m m o n and causes swelling that is slightly more proximal (Fig. 4— 12B). When such fractures occur, the distal fragment most commonly displaces dorsally. This produces the so-called silver fork deformity, in which the distal radius and hand appear dorsally displaced with respect to the rest of the forearm (Fig. 4-12C).
A localized spherical mass on the dorsum of the wrist is most commonly due to a ganglion cyst. These cysts can
Figure 4-9. Active extension increases the prominence of the finger extensor tendons.
D, radial styloid; E, abductor pollicis longus and extensor pollicis brevis; F, extensor pollicis longus; G, scaphoid; H, trapezium; I, scaphotrapezio- trapezoid (STT) joint; J extensor carpi radialis brevis and longus tendons; K, scapholunate ligament; I scaphoiunale capitate joint; M, head of the capitate; N, extensor digitorum communis tendons; O, ulnar head; P. distal radioulnar joint;Q ulnar slyloid; R, lunotriquctral ligament; S, triquetrum;
T hamate; U, lunate.
Figure 4-11. Active extension to demonstrate extensor pollicis longus tendon (arrow).
range from just barely palpable to golf ball-sized. They most commonly appear immediately adjacent to the radial wrist extensors, but they may dissect more proxi- mally and distally as they enlarge (see Fig. 4-12D). Ganglia become more prominent with wrist flexion. The transillumination test can confirm the diagnosis of a gan- glion cyst, as the ganglion glows when a pen light is shown through it (see the Manipulation section).
RADIAL (LATERAL) ASPECT
T h u m b . Rotating the patient's forearm into the neutral, thumb up, position allows the examiner to study the radial aspect of the hand and wrist directly (Fig. 4-13). This position allows a more direct view of the dorsum of the t h u m b . As with the fingers, the examiner looks for abnormalities about the thumb, first at the fingernail or areas for swelling or ecchymosis that might signify a frac- ture or joint injury. The metacarpophalangeal joint of the thumb, the first metacarpophalangeal joint, is normally quite prominent and easily visualized. Injuries to the ulnar collateral ligament of the first metacarpophalangeal joint, often called skier's thumb or gamekeeper's thumb, are a common cause of swelling at that location.
Although the t h u m b has only two phalanges, its metacarpal is much more mobile than the metacarpals of the other fingers and thus assumes some of the functions of a third phalanx. The proximal end or base of the first metacarpal, which serves as the insertion site of the abductor pollicis longus tendon, produces a visible step- off in the contour of the hand. Abnormal enlargement of this prominence is a common sign of arthritis of the basi- lar joint (Fig. 4-14) between the base of the first metacarpal and the trapezium.
Figure 4-12. A, Wrist swelling in rheumatoid arthritis (arrow). B, Swelling from nondisplaced fracture of the distal radius (arrows), C, Silver fork deformity. D, Dorsal wrist ganglion (arrow).
Figure 4-13. A, B, and C, Radial aspect of the hand. A, inter- phalangeal joint of the thumb; B, distal phalanx; C, proximal phalanx; 0, first metacarpal; E, first metacarpophalangeal joint;
F, basilar joint.
Wrist. Looking proximally from the base of the first
metacarpal, the examiner encounters a hollow or depres- sion and then a slight prominence produced by the sty- loid process of the distal radius. The hollow marks an area often known as the anatomic snuffbox (Fig. 4-15). The anatomic snuffbox is bordered dorsally by the ten- don of the extensor pollicis longus and volarly by the adjacent tendons of the extensor pollicis brevis and
abductor pollicis longus. The visibility of these tendons
may be accentuated by asking the patient to extend the thumb forcefully.
The waist of the scaphoid bone, the most common site for wrist fracture, lies deep to the anatomic snuffbox. Thus, puffy swelling and tenderness in the anatomic snuffbox following trauma suggests the possibility of a scaphoid fracture.
VOLAR (PALMAR) ASPECT
Fingers and Palm. Further rotating the patient's fore-
arm into the fully supinated position allows inspection of the palmar aspect of the hand and volar wrist. The pal- mar aspect of the normal hand is not flat but marked by
110 CHAPTER 4 Hand and Wrist
Figure 4-14. Swollen basilar joint (arrow),
a number of curves and contours (Fig. 4—16). A longitu- dinal arch begins with a prominence at the base of the hand, curves away from the examiner in the middle of the palm, and then curves back toward the examiner at the distal palm and fingers. This arch is formed by the natural resting tension that exists in the finger flexors when the wrist is extended. A transverse arch, oriented perpendicular to the longitudinal arch, traverses the hand from one side to the other. The arch is formed by the prominences of the muscles on the ulnar side of the hand
(hypothenar) and the t h u m b side (thenar). Flexing the metacarpophalangeal joints of the fingers and flexing and adducting the t h u m b accentuates these arches, producing the cupped configuration helpful for swimming or scooping water (Fig. 4-17). A break in either of these arches reflects a serious injury to the hand.
The examiner should carefully note the normal rest- ing position of the fingers. When the wrist is extended, the normal resting tension on the flexor tendons of the fingers causes them to lie in an arcade of flexion, which progresses from slight flexion of the index finger to marked flexion of the little finger (Fig. 4-18). A break in this normal arcade usually signifies a flexor tendon injury or restricted joint motion in the involved finger.
Disruption of the flexor tendons may be due to lac- eration or a closed rupture. The most common example of a closed rupture is avulsion of the flexor digitorum profundus insertion from the base of the distal phalanx of the ring finger. This condition is sometimes called jer-
sey finger because it most commonly occurs when the fin-
gers of a football player are pulled into extension as he attempts to grasp the jersey of an opponent for a tackle. This usually occurs in the ring finger, whose profundus tendon is tethered to those of the little finger and the long finger. Flexor profundus avulsion causes disruption of the normal resting arcade of the fingers because the DIP joint
F i g u r e 4 - 1 5 . A, H, and C, Uadial aspect of the wrist. A, anatomic snuff- box; ft, extensor pollicis tongus; C, extensor pollicis brevis and abductor pollicis longus.
of the involved finger comes to lie in a relatively extended would produce only a slight break in the arcade of flex- position {Fig. 4-19A). Deformities caused by flexor ten- ion, because the profundus tendon would still be able to don laceration vary depending on the tendons involved. flex both interphalangeal joints of the involved finger.
Laceration of the profundus tendon alone would produce Laceration of both tendons, however, results in loss of abil-
isolated loss of DIP joint flexion similar to that produced ity to flex both the PIP and the DIP joints of the involved by jersey finger. Laceration of the superficial tendon alone finger. This causes the affected finger to lie with both
Figure 4-16. A, B, and C, Palmar aspect of the hand. A, distal flexion crease of
index finger; B, proximal flexion crease of index finger; C web flexion crease of index linger; D, distal palmar crease; E. proximal palmar crease; F, level of metacar- pophalangeal joints; G, thenar eminence; H hypoihenar eminence.
112 CHAPTER 4 Hand and Wrist
Figure 4-17. Cupping the hand.
interphalangeal joints extended while the other fingers form the normal resting arcade (Fig. 4-19B).
The skin of the palmar surface of the hand is dra- matically different from that of the dorsum. The palmar skin is thickened, hairless, and marked with discrete creases that identify the sites of no motion. This bound down thickened skin, not only protects the underlying structures such as the nerves, arteries and tendons, but allows for stability to the skeleton for grasping and manipulating objects. Localized calluses may give clues about the person's occupation or avocations.