A Treatise on Fractures, Luxations, and Other Affections of the Bones

by P.-J. Desault

§ I.

OF THE CAUSES AND VARIETIES.

2. The division of the tendo Achillis is the result, either, 1st, of the action of a cutting instrument; or, 2dly, of muscular action: hence two very different modes of its production, the one by a wound, the other by a rupture. The first is not a very rare accident, because the projection of the tendon exposes it oftentimes to the stroke of external bodies: the second, though but little noticed by the ancients, has been frequently observed by the moderns, since their attention was called to it by Petit.

3. The manner in which the division is produced by a wound, has nothing particular in it; that by a rupture, takes place in the following manner. A man leaps over a ditch, but his spring or exertion is too weak; he reaches the opposite bank only with the ends of his feet: the line of gravity not falling on the ground, the weight of the body throws the feet into a state of violent flexion, the muscles contract with great force, to prevent a fall backwards, and, at that instant, the tendon is ruptured, in consequence of being drawn downwards by the violent flexion of the foot, and upwards by the effort of the muscles: hence it appears that Petit was deceived with regard to the mechanical cause of the rupture, which he considered as taking place at the moment of the patient’s alighting on his feet, when, as he said, the tendons were surprised, so to speak, into a state of too great tension. It is easy to apply the principles of this particular case to others that may happen, and where the position may not be the same; such as, when we leap on a table, &c. Sometimes slighter efforts have produced the effect; and, as Louis observes, dancers have sometimes ruptured the tendo Achillis by making a powerful exertion on the point of the foot, as well as by other motions.

4. Divisions produced in the first mode, may be situated in any part of the tendon. Those produced in the second, occur more particularly about its middle: to that part the effort or strain is most forcibly determined, and there the resistance is the weakest. The rupture of the tendon may, according to Petit, be either complete or incomplete; but, if we consider the simultaneous contraction of the gastrocnemii and soleus muscles, and the intimate manner in which their two tendons are united at a considerable distance above the heel, it will be difficult to conceive how these tendons can be ruptured separately. With regard to divisions produced by cutting instruments, the case is different: there, the weapon may pass half way through the tendon either from behind or laterally; and perhaps divisions of this kind are much more frequently incomplete than otherwise, in consequence of the great resistance of the tendinous fibres.

§ II.

OF THE SIGNS.

5. The superficial situation of the tendo Achillis, always renders the diagnosis of its division easy. It can be rendered difficult only by the occurrence of a considerable swelling, an accident that rarely happens. If there be an external wound, the depth to which the instrument has penetrated, and the possibility of sometimes feeling the ends of the tendon between the edges of the wound, are the first evidences of its division. If, on the other hand, the tendon be only ruptured, then at the moment when the rupture happens, a report is heard by the patient, not sharp, and like the crack of a whip, as is said to take place when the plantaris muscle is ruptured, but more dull and flat, according to the account given to Desault by a patient, whom he interrogated on the subject.

6. In either case, there occurs suddenly, if not an entire inability, at least, an extreme difficulty in either standing or walking: hence the patient falls, and is unable to rise again; but, in divisions that are only partial or incomplete (4), this sign does not occur. Between the divided ends of the tendon there exists a depression sensible to the touch. This depression is increased by the flexion of the foot, but diminished and even entirely removed by its extension.

7. The patient can spontaneously flex the foot, none of the flexor muscles being affected, and this flexion may be carried even beyond what is natural, because the divided tendon forms no obstacle to it behind. Spontaneous extension is also practicable, in as much as the peroneus longus, tibialis posticus, &c. which remain uninjured, are capable of producing that motion. Some have alleged that the calf of the leg must be increased in size by the swelling of the gastrocnemii and soleus muscles, in consequence of their state of contraction; but modern experience has shown, that there is but little reliance to be placed on that appearance.