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injured without a lesion of the main trunk which supplies the flexor longus hallucis. Occasionally, however, after extensive loss of substance due to shell injuries, the gastrocnemius and soleus have so little power left that an operation is necessary to reinforce them. If something is not done to restore the normal muscular balance, a pes cavus (hollow-foot) is almost certain to develop, since the unopposed pull of the short

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FIG. 116.-Diagram illustrating the formation of a hollow foot as result of paralysis of the Achilles tendon. A, Calf; B, the os calcis; C, the anterior portion of the foot. Normally the position of B is maintained by the upward pull of F, representing the Achilles tendon and the forward pull of F', representing the short muscles of the sole of the foot and the plantar fascia. If the gastrocnemius and soleus are paralyzed F becomes zero allowing F' to pull the os calcis forward into the position B'. At the same time the pull of the plantar muscles on the front of the foot becomes sufficiently strong to bring C into the position C'.

plantar muscles causes the os calcis to tilt, as indicated in Fig. 116.

Technic. The skin incision is best made after the manner described by Sir Robert Jones, namely in the transverse direction with or without the excision of an ellipse of skin. The healing of the transverse incision produces more or less scar

tissue which helps draw the posterior tip of the os calcis upward. The ends of the incision must extend sufficiently far to permit the identification of the peroneal tendon on the outer side and of the flexor hallucis on the inner side. The peroneal tendons are readily found just back of the external malleolus. It is of no significance which one is selected for the transfer, since the change in the course of the tendon is comparatively slight and does not necessitate interference with the lowermost muscular fibers.

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FIG. 117.-Diagram illustrating the relation of the flexor longus hallucis to the fascial planes at the bend of the ankle. To expose the tendon, the superficial layer of the ligamentum laciniatum must first be incised, the posterior tibial artery and nerve drawn toward the internal malleolus exposing the deep layer of the ligament which is attached directly to the astragalus. By incising over the groove in the bone the flexor longus hallucis tendon is exposed.

To find the flexor longus hallucis accurate anatomical knowledge is necessary. The tendon at this point of its course lies in a groove of the astragalus, covered by a band of fascia known as the deep layer of the ligamentum laciniatum, a thickened portion of the fascia cruris (see Fig. 117). To find it, the superficial layer of the fascia is first incised, exposing the nerve and the artery. These are drawn toward the internal malleolus, laying bare the deep layer of the fascia. The inexperienced surgeon then has the impression that he is directly

against the bone and that the flexor tendon is absent. Careful examination, however, will indicate where to incise the fascial layer so as to find the tendon in the bony groove.

Before the tendons are exposed, the operator has, as in the previous transplantations, prepared the site of implantation by freeing the skin of the os calcis so as to lay bare the Achilles tendon at its point of insertion. The tendon is slit longitudinally and the periosteum traumatized. On each side the slit is prolonged laterally so as to form a path directly through the Achilles tendon for the tendons to be transferred. Each of these is sutured by the stitch shown in Fig. 108, drawn through the slit in the tendon and fastened securely to the os calcis. The operation is completed by an interrupted skin suture.

In instances in which there is a marked relaxation of the Achilles tendon, it is wise to reef it. If in addition the posterior portion of the joint capsule has been markedly overstretched, it too should be shortened by inserting several strong mattress sutures.

At the knee, no sheaths are present, since friction of the quadriceps and patella tendons against the bone is prevented by the interposition of the quadriceps bursa and the kneejoint, which act as fluid buffers in exactly the same way as a tendon sheath. In transplantations at the knee, therefore, the technic must be modified to meet the changed anatomical conditions. Here the subcutaneous route is more suited to the transplanted tendon, since the subfascial would tend to lock the tendon beneath the iliotibial band. The most frequent operation is the transplantation of the biceps tendon, with or without one of the inner hamstrings, to replace a paralyzed quadriceps extensor. Though the biceps alone suffices to give extensor power, the results are bettered by combining it with one of the inner group of flexors, since the resultant line of traction is directly upward, instead of upward and outward, as when the biceps alone is transplanted.

The steps of the operation are as follows:

1. Preparation of the Implantation Site.-A 3-inch vertical incision in the midline exposes the quadriceps tendon and the upper two-thirds of the patella. Two osteoperiosteal flaps

are deflected from the latter by a T-shaped incision, as indicated in Fig. 118.

2. Reefing of the Quadriceps Tendon.-Two strong mattress sutures are inserted, one in either side of the patella, so placed as to draw it upward to the physiological limit. This is done so as to avoid breaking the law regarding suture of tendons under normal tension. Were the transplanted biceps tendon sutured under the normal tension, the patella would not be sufficiently taut, but would slip downward. Therefore, when

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FIG. 118. Transplantation of the biceps and of the gracilis for paralysis of the quadriceps femoris. (From Biesalski and Mayer: "Physiological Method of Tendon Transplantation.") The illustration shows the manner of deflecting two triangular flaps from the surface of the patella. These flaps consisting of tendon and periosteum, expose the surface of the bone to which the transplanted tendons are attached by the suture shown in Fig. 108.

the transplanted muscle contracted, part of its force would be expended in drawing the patella upward, instead of being utilized to extend the leg.

3. Exposure of the Biceps Tendon. The incision runs along the mesial border of the tendon, from the junction of the middle and lower thirds of the femur to its insertion into the head of the fibula. The external popliteal nerve is identified and drawn aside. In freeing the tendon from its insertion two

facts must be borne in mind: first, the tendon is long enough to reach the patella only on condition that its full length be secured. It is wise to make certain of sufficient length by removing a piece of the fascia of the calf with the tendon. Second, the tendon is intimately associated at its insertion with the external lateral ligament of the knee-joint. Since injury to this important ligament impairs the stability of the joint, it should be carefully avoided.

Biceps tendon

-Gracilis tendon

Periosteal flaps sutured over the transplanted tendons

FIG. 119. Transplantation of the biceps and of the gracilis for paralysis of the quadriceps femoris. (From Biesalski and Mayer: "Physiological Method of Tendon Transplantation.") The two tendons, firmly sutured to the

patella by the method shown in Fig. 109, are covered by the periosteal flaps and thus held tightly against the denuded bone. Several sutures are taken uniting the two tendons to one another, so that their line of traction is longitudinal, corresponding to that of the paralyzed muscle.

The tendon and the lowermost muscle fibres are freed upward until the operator is assured that their line of traction, when transplanted, will imitate that of the quadriceps extensor.

4. Transfer of the Biceps Tendon and Fixation.-Beginning at the anterior incision a subcutaneous channel is bored upward and outward to the point where the biceps has been freed. The channel must be sufficiently roomy to accommodate the

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