Vol. XXXIV.

No. 10

In the realm of diagnostics, Roentgenologists may be compared to "X-ray men" much as Ophthalmologists are comparable to "spectacle men". The title of this communication was chosen because a radiograph of the wrist is commonly regarded as about the simplest task of the roentgenologist. It is almost inconceivable that anybody could operate an X-ray apparatus and be unable to take a radiograph of the wrist. But diagnosis is more than radiography. Even of so simple a part as the wrist, a radiograph may be so beautiful as to delight the eye, but be very deceptive to the diagnostician. To be a reliable aid to the diagnostician, the radiographs must be so taken that they will reveal possible pathological conditions. And the diagnostician, if he is to be relied upon to make an accurate diagnosis, must be able to recognize the pathological conditions that may be present. The roentgenologist, who is entrusted with the making and reading of radiographs of the wrist for diagnostic purposes, should be familiar with the appearance of plates of the normal wrist at the age of the patient under examination, and also with the

possible normal and pathological varia

tions.

Normal Variations.

It has been common practice in our medical schools to teach that the normal adult human wrist is composed of eight bones, arranged in two rows, namely: Scaphoid, semilunar, cuneiform, pisiform, trapezium, trapezoid, Os magnum, and unciform.

For the diagnostic purposes of the roentgenologist, it is better to accept the teaching of comparative anatomy and embryology, that the adult human wrist has normally the potential possibility of thirty-three bones, of which only eight are usually present, but any of the thirty-three elements may appear bone. These are normal variations. Their differentiation from pathological conditions, especially fractures, is important and may be of medicolegal value at times.

as

The elements that may form normal bone in the carpus, may be conveniently arranged in five rows, as follows:

1. Antibrachial row-This consists of two bones or elements that may form bone, namely, the triangulare and the secondary pisiform.

No. 10

m of diagnostics, Roentge

y be compared to "X-ray

as Ophthalmologists are to "spectacle men". The communication was chosen adiograph of the wrist is regarded as about the = of the roentgenologist. It conceivable that anybody e an X-ray apparatus and › take a radiograph of the diagnosis is more than raEven of so simple a part , a radiograph may be so to delight the eye, but be ve to the diagnostician. To e aid to the diagnostician, phs must be so taken that eveal possible pathological And the diagnostician, if › relied upon to make an gnosis, must be able to recpathological conditions that sent. The roentgenologist, usted with the making and adiographs of the wrist for Durposes, should be familiar ppearance of plates of the t at the age of the patient ination, and also with the

possible normal and pathological varia

tions.

Normal Variations.

It has been common practice in our medical schools to teach that the normal adult human wrist is composed of eight bones, arranged in two rows, namely: Scaphoid, semilunar, cuneiform, pisiform, trapezium, trapezoid, Os magnum, and unciform.

For the diagnostic purposes of the roentgenologist, it is better to accept the teaching of comparative anatomy and embryology, that the adult human wrist has normally the potential possibility of thirty-three bones, of which only eight are usually present, but any of the thirty-three elements may appear bone. These are normal variations. Their differentiation from pathological conditions, especially fractures, is important and may be of medicolegal value at times.

as

The elements that may form normal bone in the carpus, may be conveniently arranged in five rows, as follows:

1. Antibrachial row-This consists of two bones or elements that may form bone, namely, the triangulare and the secondary pisiform.

2. Proximal row, consisting of six elements-The radial and ulnar scaphoids, semilunar, radial and ulnar cuneiforms, and the pisiform.

3. Central row, eight elementsRadiale externum, epitrapezium, dorsal and palmar centrales, epilunatum, hypolunatum, ulnare externum, and the epipyramis.

4. Distal row, five elements-Trapezium, trapezoid, metastyloid, capitatum proprium, and the unciform.

5. Carpo-metacarpal row, 12 elements-Paratrapezium, pretrapezium, trapezium secondarium, secondary trapezoid, epitrapezoid, parastyloid, styloid, subcapitatum, capitatum secondarium, Gruber's ossicle, the os hamuli, and the vesalianum or bone of Vesalias.

As medical students, the eight bones of the wrist seemed quite formidable. Now let us consider the possible justification of studying all of the thirtythree possibilities of normal bone formation in the human wrist. To shorten our task, we will proceed immediately to the separate consideration of these elements.

1. The triangulare or intermedium bone-This is in relation with the styloid process and cuneiform, in the triangulare cartilage. Theoretically it is between the radius and ulna on one side and the semilunar and cuneiform on the other. In the second month of the embryo it is found in about 65 per cent of cases. It is only occasionally found in the adult human wrist.

2. Secondary pisiform-This is much more rare. It occurs in close relation to the pisiform, to which it is sometimes united.

3. Radial scaphoid and

4. Ulnar scaphoid-These normally unite to form the scaphoid, or navicular, but they may remain separate and cause considerable confusion in the differentiation from fracture of the scaphoid, which many regard as the most common fracture of the wrist.

This difficulty in differential diagnosis is increased by the fact that fracture of the scaphoid and failure of the radial and ulnar scaphoids to unite probably occur with about the same frequency. Indeed, the subdivided scaphoid is probably more common than fracture of the scaphoid. Furthermore, it seems to be generally true of all the rare bones of the wrist, that they are less rugged and more liable to injury or fracture than the bones usually found in the wrist. This may be a matter of evolution. At any rate, it is important in both fractures and disease of the wrist. 5.

Semilunar or lunatum-This bone is rarely fractured. The epilunatum on the dorsal aspect and the hypolunatum on the palmar aspect, will be referred to later.

6. Radial cuneiform and 7. Ulnar cuneiform-These unite to form the cuneiform or triquetrum, and have never been seen separate in the adult wrist.

8. Pisiform-This bone is irregular in size, shape and position. It may be more proximal or more distal than usual. and sometimes projects beyond the ulnar side of the hand instead of occupying its usual position on the palmar sur

face.

9. Radiale externum-This forms the end of the tubercle of the scaphoid. Though found as a separate bone quite common among mammals, it is rare in the adult human wrist, and in the reported cases where it has been found there has usually been the history of a lesion or the evidence of inflammation, to indicate the presence of a pathological condition.

10. Epitrapezium-Is on the dorsal side of the trapezium next to the scaphoid. Seems to be a rather common finding in the anthropoids, but has been rarely found separate in man. 11. Dorsal centrale and

12. Palmar centrale-This element is quite constant in the early embryo, and