HALLUX FLEXUS.
Hallux flexus appears to have been first recognised as a separate affection only a few years ago, in 1887, and it is to Mr. Davies-Colley that we are indebted for the name and for the earliest discussion of the characters and causation of the disease. It is stated, however, by Blum that Nélaton described a “cou de cygne” of the great toe, and attributed it to the use of short boots. I have been unable to discover the reference in the works of this surgeon, but if the citation can be verified, the credit of recognising the existence and nature of the deformity will fall to him, for there is no doubt that hallux flexus is pathologically a “cou de cygne” or hammer toe. Since Mr. Davies-Colley’s introduction of the subject various contributions have been made, by Mr. Howard Marsh, Mr. Reginald Lucy, Mr. Cotterell, Mr. Ellis, and others, and I must draw especial attention to a valuable analysis of thirteen cases by my colleague, Mr. Makins, in the St. Thomas’s Hospital Reports for 1888. The complaint is by no means a rare one, for since 1887, when I began to take notes of all the cases that were brought under my observation in private and hospital practice, I have accumulated a list of thirty examples of what may be termed true “hallux flexus,” besides a number of contractions presenting a superficial resemblance to it, but resulting from arthritic lesions. I propose, as in the case of hammer toe, to separate these latter entirely from the former, because the pathological, and even the clinical, distinctions between the two classes are perfectly well marked, and it hence can only mislead to place them in the same category.
Hallux flexus may be defined as a progressive diminution of the normal range of extension at the metatarso-phalangeal, or, more rarely, at the inter-phalangeal joint of the great toe. It is unassociated with any disease of the bones, cartilages, or synovial membrane of the articulation, and originates only during the period of active growth. It is, in fact, a “hammer great toe,” and it will be found strictly analogous to the disease just described, occurring under the same conditions and affecting the corresponding articulations.[12] The name proposed by Mr. Davies-Colley has been objected to on more grounds than one. In the first place, there is perhaps a lack of soundness in the pedigree of the word “hallux.” It is a rather modern addition to anatomical nomenclature, and its sanction in classical literature is very dubious. In Plautus there is an expression “hallex viri,” implying a little man, a “thumbling,” and the words “hallex,” “allex,” and “hallux” have been used by other writers with a somewhat questionable signification for the great toe. A purist might indeed be justified in opposing the adoption of either “hallex” or “hallux,” and especially the latter; but the convenience attached to a distinctive name for the great toe in place of that of “pollex,” which is applied also to the thumb, is so great that we are not tempted to be hypercritical on philological grounds. A more serious objection has been raised against the adjective “flexus,” because in the majority of cases the toe is not actually in the position of flexion; but the term “flexion” may be applied in the sense of movement as well as in that of position; and although the great toe in hallux flexus may not reach the position of flexion, it has passed through the motion of flexion before it has attained the line of direction in which it is found in the disease.
Symptoms.—In a typical case of hallux flexus the patient, usually a boy near the age of puberty, suffers some little pain about the metatarso-phalangeal articulation of the great toe in walking, at the moment when the weight of the body falls chiefly upon this joint. Rest affords complete relief, and the structures about the articulation show no signs of inflammation. As time goes on the pain increases and becomes associated with a sense of rigidity of the toe, and the power of full extension becomes lost. The diminution of the range of movement is very gradual, and usually it is not until the proximal phalanx can no longer be extended beyond a line corresponding to the prolonged axis of the metatarsal bone that the condition is brought before the surgeon, but in more extreme examples the toe becomes actually bent below this axis, so that it forms with the metatarsal bone an obtuse angle with plantar opening. The foot is now seriously crippled. Over-use in walking induces much suffering, and any attempt at passive extension is extremely painful, while flexion still remains unimpaired. The head of the metatarsal bone thrown into prominence by the unwonted position of the proximal phalanx looks abnormally large. In some cases a reflex hyperæmia of the tissues surrounding the joint may be induced by forced exercise; but there is rarely, if ever, any effusion within the capsule. The patient finds walking more and more difficult, and to avoid pressure upon the contracted articulation limps on the outer edge of the foot; but this gives little relief, and at last he is compelled to rest. In the more severe cases the patient consults the surgeon; in the slighter forms he puts up with the inconvenience, and we may assume that he recovers without professional assistance, for the condition is very seldom found after the attainment of full adult life.
An analysis of my series of thirty cases shows that the deformity is much more frequent in boys the number including only three girls. (In the series of thirteen cases recorded by Mr. Makins the proportion of males to females was eleven to two). It was bilateral in one case only, right-sided in nineteen cases, left in ten, and affected the metatarso-phalangeal articulation in every instance, except two in which the distal joint was involved. ([Fig. 11.]) In only three cases did the flexion pass the prolonged axis of the metatarsal bone, the angle reached in the worst example being 150°; in the rest the toe during full extension was either in a line with the metatarsal bone, or formed with the latter a very obtuse angle, 170° to 160°, with the opening towards the dorsal aspect. The ages at which the symptoms were first noticed ranged from twelve to eighteen, in the greater number lying between fourteen and sixteen. The associated deformities were: excessive length of toe in two cases, this amounting to a distinct giant growth in one, hammer toe (second) in one, hallux valgus (slight) in three, flat-foot in four, and slight varus in one. In the other cases the feet were perfectly normal in shape. The duration of the disease before the patient came under treatment varied from three months to four years. Occupation appeared to exercise little influence; the subjects were mostly schoolboys, labourers, and errand boys, but there was no reason to believe that there had been any unusual strain upon the powers of endurance, except in two instances. In two cases the condition was attributed to the use of short boots, but in the others no complaint was made as to the foot covering, and that in wear at the time of attendance was as unobjectionable as the materials and plan of the modern boot will allow. Constitutionally, the patients were, for the most part, a little below the average in physique; one (a girl) was tuberculous, and one was a child of rheumatic parents, but none had suffered from rheumatism. The result of inquiries with respect to inherited tendencies was less striking than in the case of hammer toe. In one instance the father had double hammer toe, in another a brother had suffered from hallux flexus at the age of sixteen, and became cured without medical intervention in the course of three years; but in the majority no satisfactory information on the point could be obtained.
Fig. 11.
Hallux flexus of the distal joint.
Progress.—There can be little doubt that the natural tendency of the complaint is to subside under the mechanical influence of ordinary exercise, and hence, although the deformity is fairly common in youth, it is rarely found in fully developed adults, except where the distal joint is affected. In one case of this kind the contraction began about puberty, and was still present at the age of fifty-two, but the defect never interfered materially with locomotion. It is possible that some of the ordinary cases terminate, as suggested by Mr. Davies-Colley, by conversion into hallux valgus, but my inquiries have failed to confirm this.
Pathology.—The origin of the condition may be explained in the same manner as that of hammer finger and hammer toe. There is a physiological variation in the range of movement permitted in the articulations of the great toe similar to that demonstrated in the fingers and lesser toes, and in examining a number of healthy feet it will be found that the position of extreme super-extension at the metatarso-phalangeal joint may lie at any point between 30° and 110° beyond the prolonged axis of the metatarsal bone; but if the movement of extension be checked at less than 30°, the symptoms of hallux flexus supervene. The chief distinctive feature in the anatomy of the joint lies in the substitution of two sesamoid bones, with their tendons and connecting tissue, for the glenoid plate developed in all the other articulations, and it is those structures that receive the distal attachment of the plantar fibres of the lateral ligaments. ([Figs. 12 and 13.]) The function of the lateral ligaments, however, remains the same as in the other toes, and the range of the movement of extension is governed by the development of their plantar fibres.
Fig. 12.
Bones and ligaments in hallux flexus. 1. Lateral ligament of metatarso-phalangeal joint; inferior fibres attached to sesamoid bone; 2. Lateral ligament of inter-phalangeal joint; inferior fibres blending with glenoid plate.
Fig. 13.
Hallux flexus of the distal joint.
The opportunities of examining the morbid anatomy of the complaint are necessarily very few. Mr. Davies-Colley’s specimen proves that the structures restraining the movement of extension correspond to those concerned in the production of hammer toe, those fibres of the lateral ligaments which blend with the osseo-tendinous structures replacing the glenoid plate; and the cause of the deformity in both cases appears to be an irregularity of nutrition by which the ligamentous fibres undergo imperfect longitudinal development, and consequently induce premature arrest of the movement of extension. This developmental defect is probably unconnected with any special error in the form of the shoe. Like hammer toe, the deformity occurs at the age most prone to nutritive disturbance; but hallux flexus tends to undergo cure without the help of the surgeon, because the weight of the body serves as an extending force, which sooner or later proves stronger than the resistance opposed; while in hammer toe the lesser digit is not essential to locomotion, and its retraction at the metatarso-phalangeal joint frees the inter-phalangeal joint from all necessity for action, and favours the permanency of the vicious position.
Hallux flexus of the distal joint must be distinguished from the paralytic hallux retractus which simulates it (see [p. 127]).
Treatment.—Bearing in mind the fact that true hallux flexus has a natural tendency to recovery, it is obvious that the graver surgical operations can seldom be called for. In the case of hammer toe a resection of the articulation may be undertaken without hesitation, because the deformity is more likely to become aggravated than relieved by lapse of time, and because the function of the digit is not sensibly interfered with by obliteration of the joint; but the destruction of the metatarso-phalangeal joint of the great toe entails a permanent alteration of gait. The treatment I have adopted in the milder cases is to instruct the patient to perform a regulated series of passive movements of the toe by the use of his hands, aiding the process by massage of the lower and inner side of the foot, and as the tenderness passes away to practise walking on tiptoe until the normal degree of extension is restored. In more severe examples I have extended the joint forcibly under an anæsthetic, afterwards fixing it in the super-extended position in a plaster splint for three weeks. The result of this plan has been so satisfactory that I have found it unnecessary to do more, but should it fail, we have the choice of several plans: (1) Section of the lateral ligaments, subcutaneously or by means of an open wound. (2) Excision of the head of the metatarsal bone, an operation necessarily involving obliteration of the joint and a shifting of the point of support to the distal joint, which is less well fitted to discharge the office. It might, however, be permissible in certain cases. (3) Excision of the proximal half of the first phalanx. This has been successfully effected by Mr. Davies-Colley. (4) Osteotomy of the metatarsal bone above the head, with excision of a dorsal wedge proportioned to allow the toe to be placed in a position of slight super-extension, the articulation being preserved intact.
It is improbable that any of these more severe measures will be required if the method of forcible reposition be well carried out.