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the fibres of the muscle near the trochanter, but much less than were the muscle divided directly in the course of the

nerve.

In laying bare the sciatic in the thigh, the relation of the long head of the biceps muscle is of great importance. It is to be recalled that this portion of the muscle has its origin from the tuberosity of the ischium in common with some of the inner hamstring muscles, and that therefore its course must be a slanting one, from within outward. It crosses the nerve in the upper third of the thigh. Above this point of crossing, it should be drawn to the inner side in order to expose the nerve; below this point, it should be drawn to the outer side (see Fig. 91). Adherence to this rule will save the operator much inconvenience.

Internal Popliteal.-An incision directly in the middle line of the popliteal fossa lays the nerve bare. Like the sciatic, it is almost always embedded in a fatty envelope, even in thin individuals. It should therefore be sought where the operator sees the adipose tissue between the muscles.

The two important branches to the heads of the gastrocnemius

pass off from the nerve near the upper end of the popliteal fossa, and should always be carefully identifieb, so as to avoid injury.

Posterior Tibial.-In the lower two-thirds of the leg the nerve is best exposed by an incision on the mesial aspect following the inner border of the soleus muscle and the Achilles tendon. The Achilles tendon and the muscular mass consisting of soleus and gastrocnemius are retracted outward, baring the deep layer of the fascia. When this is incised, the nerve is found lying directly beneath it. Reference to Fig. 92, a diagrammatic cross-section through the calf in the midthird, will clarify these relations.

In the upper third of the calf, this incision cannot be employed, since the nerve lies too near the midline. It is exposed by a median incision which is deepened through the fibres of the gastrocnemius and soleus.

External Popliteal.The tendon of the biceps serves as a guide for this nerve. The relation of the two structures is not always exactly the same, since in some individuals the tendon overlaps the nerve, whereas in others a gap of a quarter of an inch may separate them.

Anterior Tibial.The nerve is found by exposing the outer border of the tibialis anticus muscle. Near the ankle, the extensor proprius hallucis lies on its outer side; nearer the knee, the extensor longus digitorum. A large branch to the tibialis anticus muscle passes off almost immediately after the separation of the external popliteal nerve into its terminal branches.

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Compartment for the Gastrocnemius and Soleus Fig. 92.-Diagrammatic cross-section of the calf in the lower half, illustrating the fascial compartments for the muscles and the location of the posterior tibial nerve. The arrow indicates the point of incision for exposing the nerve.

The gastrocnemius and soleus are drawn toward the fibula laying bare the deep layer of the fascia, beneath which the nerve lies.

Musculocutaneous Nerve. This lies directly in the substance of the peroneus longus. The sensory portion emerges from the fascia in the lower third of the calf near the septum which separates the peroneal muscles from the anterior extensors.

External Saphenous Nerve.-The significance of this nerve lies in its value for transplantation purposes. It is found directly in the midline of the calf in immediate association with the external saphenous vein, which frequently lies directly over the nerve hiding it from the view of the inexperienced operator.

Postoperative Treatment.-Subsequent to the operation the treatment as practised before should be continued; that is the extremity should be properly splinted and the paralyzed muscles should be given daily massage and electrical stimulation. Whenever possible the patient should be allowed to use the extremity, since in this way the circulation is best kept normal.

It is advisable to keep the patient under observation until the muscles have recovered power. If for economic, military or social reasons, it is impossible for the patient to remain in the hospital, he may be allowed to go about his work, reporting daily for the necessary treatment and for examination.

Prognosis.-Concussion and contusion of the nerve yield rapidly to non-operative treatment. Scar tissue formation external to the nerve without interruption of the continuity of the nerve fibres is easily removed and return of function should occur in approximately 100 per cent. of the cases. Endoneural scar formation on the other hand does not yield as readily to treatment. When but slightly developed, so that the internal neurolysis can be practised, the prognosis is more favorable, than in those instances where owing to extensive scar tissue development, excision of the neuroma is necessary with subsequent nerve suture. When the projectile has injured a small portion of the nerve resulting in a comparatively small scar, excision without complete division of the nerve gives excellent results in the majority of cases, because of the accuracy with which the nerve ends can be brought into apposition (see Fig. 84).

When complete nerve division has occurred, cure results, so far as I can judge from reliable statistics of other operators and from my own experience, in not more than 40 per cent. of the cases. This poor result, though partly due to the technical difficulties associated with the secondary nerve suture, undoubtedly indicates the need for careful experimental work

improve the present operative technic.

CHAPTER IX

INJURIES TO TENDONS AND TENDON OPERATIONS

The tendons most frequently injured in military practice are those of the hand and fingers. As a rule, the projectile traversing the hand splinters one of the metacarpal bones and divides one or both groups of tendons. The infantry projectile seldom does damage to the tendons of more than one finger unless its course happens to be an oblique one.

Shell fragments, however, can produce much more extensive destruction. The proper immobilization of these injuries has already been discussed in Part I. When both flexors and extensors have been injured, there is little to be done except immobilization in the midposition. If either flexor or extensor has suffered an isolated injury, then the hand and fingers should be so splinted as to relax the tension upon the injured tendon and afford the maximal opportunity for contact between the tendon ends. It is rarely possible to perform a direct tendon suture, owing to the infection which usually accompanies the injury.

These injuries to tendons constitute, however, only a minor field in tendon surgery. A far wider scope is given by those paralytic conditions in which owing to the impractibility of nerve operations, tendon transplantations should be executed to restore the normal muscle balance. Since all types of tendon operations, whether they be suture for traumatic lesions, or transplantations for paralysis, are based upon the same principles, it is wise before describing the specific operations for injuries to the tendons of the hand to outline these fundamental facts.

During the winter of 1912, at the suggestion of Prof. Lange of Munich, Henze and Mayer investigated the cause of the adhesions which develop subsequent to tendon transplantations. In their work, attempt was made to prevent the development of the adhesions by surrounding the tendon with various substances: vaseline, bismuth paste, fascia, veins, cargile membrane, thin tubes of rolled silver, etc. None of these methods gave good results; in fact, with the exception of the cargile membrane, there were more adhesions after implantation of these substances than before. The cargile membrane proved to be more favorable, yet by careful control experiments it was conclusively shown that it had no specific effect in preventing adhesions. Finally the suggestion of Biesalski was followed, and the transplanted tendon drawn through the sheath of the paralyzed. All of these sheath experiments resulted excellently; even after 4 weeks' fixation there were no adhesions to the operated tendon, but it was able to glide to and fro within the sheath with almost the normal range of motion.

This clear-cut evidence in favor of Biesalski's method, pointed the finger in the direction of a technic which would coördinate the operation with the normal gliding mechanism of the tendon. It became evident, however, as soon as this idea was followed out that the knowledge of tendon anatomy and physiology was entirely inadequate for the purposes of exact surgical work. Therefore, before an operative system could be evolved, it was necessary to study the anatomy and physiology of tendons from a new point of view. No one, neither physiologist, anatomist, nor surgeon, had as yet considered the questions of how a tendon glides, the exact function of the tendon-sheath, the relation between the sheath and the connective-tissue structures surrounding the tendon, the tension of the tendon, nor a number of other important physiological problems.

This research work was conducted by dissections on the cadaver controlled by microscopic examination, by experiments on dogs, and by observations during operations on human beings. The results of the work are published in full under the title “Die Physiologische Sehnenverpflanzung” (Springer, Berlin; Paul Hoeber, New York). The reader is also referred to three articles by the author published in "Surgery, Gynecology and Obstetrics" for February, March and April, 1916.

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