REIDER PART 143

_ Chapter 4_Hand and Wrist 133

Metacarpals

Fractures of the metacarpals of the fingers are common, especially in the fourth and fifth metacarpals. These fractures may occur just proximal to the metacarpal head or within the metacarpal shaft. Point tenderness and swelling of a particular metacarpal suggests the possibil-ity of fracture at that location; palpation may also allow the examiner to detect the deformity caused by a dis-placed fracture of one of these subcutaneous bones.

Fractures of the first metacarpal of the thumb may occur in the shaft or at the base, where the most common type is called Bennetfs fracture. Tenderness and swelling at the base of the First metacarpal following trauma should lead the examiner to suspect such a fracture.

Wrist

Palpation of the dorsal wrist begins on the radial side (see Fig. 4-10). The firm bony resistance of the radial styloid is a reliable landmark for orientation at the radial side of the wrist. Continuing distally from the radial styloid, the examiner can identify the tendons of the first dorsal compartment, the abductor pollicis longus and the extensor pollicis brevis. This is the first of six synovial compartments into which the tendons of the dorsal wrist are grouped. These tendons form the volar border of the anatomie snuffbox. Tenderness or palpable synovial thickening of the first dorsal compartment over the radial styloid suggests a diagnosis of de Quervains disease.

About 2 cm to the ulnar side of the radial styloid, the examiner can palpate a smali bump on the dorsum of the distal radius known as Lister’s tubercle. Listers tubcrcle is an important landmark for palpating the bones and lig-aments of the dorsal wrist. Running past the ulnar side of Lister s tubercle to its insertion on the dorsum of the distal phalanx of the thumb is the cxtensor pollicis longus tendon. The extensor pollicis longus makes up the third dorsal compartment and forms the dorsal border of the anatomie snuffbox.

Palpable just distal to the radial styloid, within the confines of the anatomie snuffbox, is an area of bony resistance corresponding to the waist of the scaphoid bonę (see Fig. 4-9B). Slight ulnar deviation of the wrist may make the scaphoid morę easily palpable. Tenderness over the waist of the scaphoid is an important finding bccause fractures at this location are common and noto-riously difficult to diagnose radiographically.

Gentle palpation further distal in the anatomie snuffbox reveals a pulsating structure that is the dorsal branch of the radial artery. Firmer palpation just distal to this pulsc reveals the bony resistance that corrcsponds to the trapezium. Another 3 mm or 4 mm morę distal, the examiner should be able to palpate the outlines of the trapeziometacarpal joint, or basilar joint, of the thumb. Tenderness here suggests degenerative arthritis, which is particularly common in women over 50 years. If arthritis is present, palpable osteophytes may be noted. Other tests for arthritis or instability of the basilar joint are described in the Manipulation section.

Just to the ulnar side of the junction between the scaphoid and the trapezium, the examiner should be able to palpate a deep indentation that corresponds to the scaphotrapeziotrapezoid (STT) joint.

The tendons of the extensors carpi radialis longus and brevis pass beneath the extensor pollicis longus before they insert on the dorsum of the sccond and third metacarpals. They can be most easily palpated if the patient is asked to extend the wrist against resistance. These tendons constitute the second dorsal compartment and lie over the dorsum of the distal radius. Distal to the radius and under these tendons is the site where a dorsal wrist ganglion is most likely to appear. A large ganglion presents as an obvious mass, but carcful palpation may be necessary to detect a smali one, which feels like a firm spherical mass only a few millimeters in diameter.

Palpating just distal to Lister’s tubercle with the wrist in slight flexion, the examiner’s finger falls ovcr the distal edge of the radius into the radiocarpal joint at the site of the scapholunate ligament. This ligament links the scaphoid, which is located to the radial side of Listers tubercle, and the lunate, which extends from that point to about the middle of the ulnar head.

As the palpating finger passes distally, a second indentation can be felt about 1 cm morę distal from the scapholunate joint. This indentation corresponds to the radial portion of midcarpal joint or, morę specifically, the scapholunate capitatc joint. A position of slight flexion of the wrist may make the midcarpal joint morę palpable. Tenderness, swelling, or bogginess at this site suggests injury to the ligaments connecting the scaphoid, the lunate, and the capitate. As the examiner continues palpating in the ulnar direction, an area of firm resistance corresponding to the head of the capitate is felt just distally.

The extensor digitorum communis tendons occupy the fourth dorsal compartment of the wrist. These tendons can be palpated as a group at the point where they tra-verse the wrist by asking the patient to actively extend the fingers (sec Fig. 4-9). Lumpy synovial thickening around these tendons as well as the other dorsal tendons is a common finding in rheumatoid arthritis, or in tendon synovi-tis. To differentiate synovitis form a large ganglion, have the patient flex and extend the fingers. A ganglion does not move or change its shape. Synovitis becomes diffuse with flexion and tighter with extension. This tightness or fullness will protrude distal to the extensor retinaculum and cause the synovitis to form a heart shape.

The little finger has the distinction of having its own individual extensor tendon, the extensor digiti minimi (quinti). This tendon occupies the fifth dorsal compartment and traverses the wrist over the distal radioulnar