The deformities of the fingers and toes

by William Anderson

CONTRACTION OF THE FINGERS DUE TO DEVELOPMENTAL IRREGULARITIES IN THE BONY AND LIGAMENTOUS ELEMENTS OF THE ARTICULATIONS.

There are certain affections of the fingers which have hitherto attracted little notice, but are interesting on account of their relationship to deformities of much greater frequency in the lower extremity. These are conditions of abnormal flexion and of lateral deviation of the phalanges at the inter-phalangeal articulations, the first of which corresponds exactly to the well-known deformity of the foot called “hammer toe.”

Fig. 6.

“Hammer Finger.”

“Hammer finger” ([Fig. 6]) is not a rare complaint, although much less familiar, possibly because much less troublesome, than hammer toe. It may be defined as a permanent flexure of one or more digits, nearly always at the first or second inter-phalangeal joint, and unassociated with inflammatory or degenerative disease in the articular structures, or with any evidence of paralytic or spastic phenomena in the muscles. It is strictly limited in onset to the developmental period, and may manifest itself at any time between birth and adult life, possibly even before birth in some instances. It is more common in girls than in boys. The digit most frequently attacked is the little finger, and the proximal inter-phalangeal joint is more often affected than the distal joint. It is usually symmetrical. The contraction is slow, progressive, and painless, and becomes arrested spontaneously at any degree of flexion, but seldom goes beyond an angle of 90°. The joint cannot be extended by any ordinary force except in the earliest stage, and even then the bent position is immediately resumed after the cessation of the effort. Flexion, on the other hand, is complete and of fair power. No alteration is produced in the deformity by flexion of the wrist, a fact which proves that the main obstacle to extension does not lie in the tendons. There are no contracted fascial bands, and, as a rule, the skin is normal, but occasionally a small longitudinal fold may be present in the angle of flexion. In rare instances the resistance to extension is capable of yielding suddenly with a spring-like action, and a similar movement recurs as the joint is replaced in the position of flexion. These cases are usually classed with the condition known as “trigger finger.” The contraction also occurs in the metacarpo-phalangeal joint, but very rarely attains a degree marked enough to attract the attention of patient or surgeon. In 800 children examined at the Central District School at Hanwell by Dr. Litteljohn and myself, this affection was found seven times—five times in girls, twice in boys, the ages of the subjects ranging between eight and fourteen. In all these the deformity was confined to the little finger, and in six cases it was bilateral. The proximal inter-phalangeal joint was affected in ten, and the distal joint in three of the thirteen digits. The angle of flexion measured from the prolonged metacarpal axis, ranged between 20° and 80° in the different cases. A contraction of less than 20° was frequent, but the deformity was so slight that the cases were not recorded as pathological. Besides these examples, I have met with several cases in adult women, in whom the defect is said to have originated in early childhood. The little finger was affected in all, but in one the ring finger, and in another the ring and middle fingers were also involved. Only the last was unilateral. The following case may serve as a type of the more troublesome forms:

G. B., a domestic servant, aged twenty-two, was admitted into St. Thomas’s Hospital in June 1889, with contraction of the third, fourth, and fifth fingers of the right hand at the first inter-phalangeal joints. The patient, a strong, healthy girl, quite free from neurotic tendencies, stated that her little and ring fingers had been contracted from early childhood, and that the condition had increased slowly but progressively to the present time. The middle finger became similarly affected about five months before admission. She had never suffered from pain, and the parts had been free from all sign of inflammation; the deformity, however, caused very great inconvenience in her occupation. Two months before admission an attempt had been made to relieve the flexion of the little finger by subcutaneous section of the fascia, with the result of inducing a traumatic contraction of the metacarpo-phalangeal joint. The family history was negative. On examination the little finger was found to be flexed at an angle of 90° at the first inter-phalangeal joint, and the metacarpo-phalangeal joint was bent at an angle of 120° by cicatricial contraction of the skin and subcutaneous tissue (the result of the operation alluded to). The ring finger was flexed at the first inter-phalangeal joint to about 110°, and the middle finger at the corresponding articulation to about 150°. In the case of the inter-phalangeal joints, the movements in the direction of flexion were quite free and of normal power, but extension was strongly resisted by ligamentous tension at the points named. No increase in the range of movement was gained by flexion of the wrist. A first operation was undertaken for the relief of the cicatricial contraction at the proximal joint of the little finger. The tense integumental band was divided, and after straightening the joint a flap was dissected from the ulnar side of the digit opposite the point of incision and twisted into the gap. ([Fig. 4.]) The wound united by first intention, and the result was permanent. A week later an operation was performed upon the first inter-phalangeal articulation of the same finger. The lateral ligaments were divided subcutaneously near their proximal attachment, and it was found that the joint could then be straightened by the use of moderate force; but on the discontinuance of the extension the contraction was reproduced by the elastic tension of the flexor, except during flexion of the wrist. The hand was placed upon a splint. The patient, who did not bear restraint well, left the hospital, and has since been lost sight of.

There is little doubt that in this case the primary contraction was due to imperfect evolution of the ligaments, and that the shortening of the tendons was secondary. The reason for accepting this order of phenomena is that a pure myogenic contraction does not readily lead to changes in the joint structures, because the articulations are capable of full extension while the flexor tendons are relaxed by bending the wrist, and hence the limitation of movement is not constant. (See Case recorded on [page 58].) On the other hand, in a permanent contraction of a finger-joint occurring during the period of active growth the flexors are never stretched to their full extent, and consequently do not undergo their normal longitudinal development; but should such a contraction originate in an adult the case is different, as muscle and tendon show very little disposition to undergo active involution in the direction of their length after their complete development is attained; and hence after division of the abnormal bands in true Dupuytren’s disease the tendons do not impede the complete extension of the digit. This law, that joint contractions commencing in youth lead to shortness of muscle tendon, while those beginning in adult life do not, is worthy of the attention of the surgeon.

Pathology.—The affection is of some pathological importance, because it affords a simple test case by which many other questions of larger moment may be decided. It has been demonstrated that the permanent obstacle to extension of the contracted joint is to be found in the ligaments, there is no evidence of either muscular or nervous impairment or of any inflammatory changes in or about the joint, the process of contraction is slow and painless, and the condition always originates and progresses to its maximum during the term of active growth. In order to understand the significance of the complaint, it is necessary to dwell upon some facts in digital anatomy and physiology that have not received the consideration they deserve. If we examine a number of hands, it will be found that there is a remarkable wide physiological variation in the range of movement at the phalangeal articulations in different individuals, and it requires but a small departure outside the physiological limits of variation to constitute the pathological deformity under consideration. The results of my own observations are as follows: (1) At each of the digital joints the distal bone, starting from the position of extreme flexion, passes through a variable number of degrees before it reaches the point at which it is arrested by tension of the ligaments. In the metacarpo-phalangeal joint the angle formed between the two bones during extreme flexion is usually about 80°, and the entire extending movement from this point may be represented in the healthy hand by any number of degrees between 90 and 190. That is, in one person the motion is arrested a little before the axis of the phalanx reaches a line with that of the metacarpal bone; in another it may be possible to continue the extension until the two bones form an angle with a dorsal opening of 90°. At the first inter-phalangeal joint there is a similar but less extensive variation. The extreme flexion angle is 60° or 70°, and the full extension may be checked as soon as the axes of the two bones are in the same line (frequently a little before this point is reached), or may be carried on 30° beyond. In the distal joint the flexion angle is about 80°, and extension may be checked when the two bones are in the same line, or may be capable of continuation for 40° or more. In the thumb the range of movement at the metacarpo-phalangeal joint varies from 80° to 170°, and at the inter-phalangeal joint from 90° to 120°, in different persons—i.e., the physiological variation in the two articulations is 90° and 30° respectively. The diagram ([Fig. 7]) may help to render this clear. It is not only in different individuals that such variations are apparent, but the fingers of the same hand and corresponding fingers in opposite hands may differ from each other to a marked degree in range of extension. The super-extension is usually greatest in childhood, and undergoes great diminution as adult life is approached, although in many cases it is persistent; as a rule, however, the limitation is in direct proportion to the strength of the hand, and is hence nearly always greater in the left hand than in the right. These peculiarities are matters of common observation, and popular expressions have ever been coined to represent the extremes in the range of variation. Thus a person who is able to bend his joints backwards to a conspicuous degree is said to be “double-jointed,” and one who cannot extend them beyond the straight line is called “stiff-jointed”; and it is well known that “double-jointedness” and “stiff-jointedness” run in families, and in some cases may be traced through several generations. In the author, for example, the metacarpo-phalangeal joints of the index and middle fingers of the right hand are “stiff,” while those of the left are capable of a super-extension of 45° beyond the metacarpal axis; and precisely the same condition was present in his father, and has been transmitted to his son.

Fig. 7.

A. Skeleton of finger with lateral ligaments; 1. Metacarpal bone; 1a. Anterior fibres of lateral ligament blending with glenoid plate; 2. Metacarpal phalanx; extension checked by short anterior fibres of lateral ligament (1a) at line of metacarpal axis; 2a. Super-extension permitted when 1a long; 3 and 3a. Middle phalanx under conditions similar to 2 and 2a; 4 and 4a. Ungual phalanx.—B. Hammer finger; extension at first inter-phalangeal joint arrested by imperfect longitudinal development of anterior fibres of lateral ligament.—C. Palmar aspect of first inter-phalangeal joint (left middle finger); 1. Metacarpal phalanx; 2. Middle phalanx; 3. Anterior fibres of lateral ligament decussating with those of the opposite side; 4. Glenoid plate.

It may be of advantage to describe the articular structures of one of the finger-joints somewhat in detail. The capsule of an inter-phalangeal joint is formed on the dorsal aspect by the expansion of the extensor tendon, reinforced by the transverse fibres (the ligamenta dorsalia of Henle), which bind the tendon to the bone and lateral ligaments; on the palmar surface of the articulation is a glenoid plate of fibro-cartilage firmly attached to the anterior border of the distal bone, but very feebly connected with the neck of the proximal bone, and fused intimately with the anterior fibres of the lateral ligaments; lastly, at the sides of the joints are the radial and ulnar lateral ligaments, the attachment of which it is important to study closely, as they are often imperfectly described in anatomical text-books. The fibres of each lateral ligament are attached above to a little tubercle at the side of the head of the first phalanx, and from this point they radiate in a fan-like manner—the more posterior passing to the side of the base of the second phalanx, the rest blending with the glenoid plate, and through the intermediation of this are connected with the anterior border of the base of the distal bone, decussating to some extent with fibres of the opposite ligament. ([Fig. 7, C.]) The strongest part of the glenoid plate, in fact, is made up of these ligamentous fibres; and it is these which, relaxed in flexion, become progressively more and more stretched during extension, and at length by their tension bring the movement to a close, but, as already shown, the point at which the maximum tension is reached varies to a large extent in different individuals.

The physiological variations in the range of movements are thus to be explained by variations in the relative length of the anterior fibres of the lateral ligaments. The ideal constitution of a joint depends upon the existence of a certain ratio between the growth of bone and that of ligament. Should the ligaments grow in excess, their redundant length will permit great super-extension, and may even cease to check the movement; but if the bone grow relatively faster than the ligaments, the anterior portion of the latter will the sooner become tense during extension, and where this disproportion is exceptionally great the motion may be checked before it attains physiological completeness, the result being a “hammer finger.” Irregularities of development are most likely to occur in those joints which, for one or other reason, have the least functional activity. In the hand the little finger is much less powerful than its fellows; and in association with this it may often be noticed that the fourth tendon of the flexor sublimis is reduced to a mere thread; in the foot the same thing is observed in the corresponding digit, but in a more marked degree, and it is the degenerate little toe which is most liable to the “hammer deformity.”

We may then define hammer finger as the result of a developmental irregularity of the first or second inter-phalangeal joint (rarely of the metacarpo-phalangeal joint) by which the anterior fibres of the lateral ligaments become prematurely tense during extension, and so check that movement before it attains its normal physiological limit. It is precisely analogous to hammer toe; but it is of less frequency than the latter affection, because while civilisation sedulously cultivates the freedom and precision of action in the fingers, it devises foot-coverings to repress the natural play of the toes. The tendency to the deformity may be transmitted by descent through an indefinite number of generations.

Diagnosis.—Spurious hammer finger, like false hammer toe, may occur from—(1) articular lesions due to rheumatism, rheumatoid arthritis, gout, tuberculosis, and inflammations of traumatic origin; or (2) from interference with the muscular functions by paralysis of the extensors or by spastic contraction of the flexors. In the first group the joint will be found in a more or less complete state of ankylosis, movements in all directions being impeded. In the second group the articulation, although contracted, is freely mobile under passive force, unless, as in some congenital paralyses, irregularities of development in the articulations be superadded.

Treatment.—The treatment of hammer finger is a far less simple problem than that of hammer toe, because in the toe the sacrifice of the movement of the affected articulation does not sensibly impair the utility of the digit, while in the fingers an ankylosis of the first inter-phalangeal joint in the position of either flexion or extension would be even more inconvenient than the ligamentous contraction. The measures available are (1) passive movement; (2) subcutaneous section of lateral ligaments, with or without tendon lengthening; and (3) amputation. In the milder cases a persevering use of passive motion will in time effect a cure; but when the contraction has reached an advanced degree it may be impossible to make an impression by this means. We may then divide the lateral ligaments, and keep the fingers straight by means of an extension splint while the tendons are relaxed by flexion of the wrist, trusting to subsequent massage and passive motion, or, failing this, to tendon lengthening (by a process to be described later), to overcome the resistance of the shortened muscles. Section of tendons within the theca is useless, because no uniting material is thrown out between the divided ends. As a last resource, amputation may be demanded to remove a useless and inconvenient member.

Lateral versions of the phalangeal joints.—Lateral versions of the fingers are intimately associated with hammer finger in pathology, and the two distortions are sometimes combined. The lateral inclination, which seldom exceeds 25°, may affect either of the inter-phalangeal joints, but is more frequently in the distal phalanx. Like the “hammer” deformity, it is usually found in the little finger, and is symmetrical. The version is nearly always towards the radial side, and the movements of the joint are a little impaired. Amongst eight hundred children in the Hanwell School were found six cases, of which five were double and affected the little fingers, the sixth being in the fourth digit and unilateral; in two the version was associated with slight hammer flexion. It is occasionally seen in the index finger, and the version is then towards the ulnar side. The condition is rather unbecoming than inconvenient, and cases are seldom brought to the surgeon for relief. It is a result of irregularity of development, the condyle growing a little more rapidly on one side than on the other. The constancy of the radial direction of the version of the little finger is probably explained by the fact that any lateral pressure to which this digit is subjected is from the ulnar side, while in the index finger the pressure is more often from the radial side, and hence an ulnar distortion is here the more usual. The deflected joint may be straightened by the use for a few weeks of a narrow metallic side splint, jointed opposite the articulations. No operation is required.

Exaggerated forms of distortion of the fingers may occur in rheumatoid arthritis, gout, or chronic rheumatism, and in various nervous affections,[2] but these rarely call for surgical treatment.