Equinus deformity of the ankle

This is the most common polio deformity in a child, and is fortunately the easiest one to correct. Provided he has no severe valgus or varus deformity, you can correct a milder equinus deformity with serial casts, each of which will release his deformity a little more. Specialized polio services caring for large numbers of children tend to neglect casts in favour of tenotomy, which is less trouble. But if you are inexperienced, you will find serial casts very useful.

If a child has a more severe deformity, he needs his Achilles tendon lengthened. You can do this: (1) open or (2) closed. The closed operation is simpler, and there is less risk of infection, or keloid formation. The advantage of the open method is that it is possible to divide the posterior capsule of his ankle joint, if this is necessary, as it may be in polio. The risk in both these methods is that you may cut his posterior tibial nerve and vessels, and cause gangrene of his toes, but this should never happen, if you follow the instructions carefully. Contributors differ on the place of the open method. Ronald Huckstep feels that it now has no place in the management of polio. James Cairns uses the open method for more severe deformities, because he can do a posterior release of the ankle at the same time.

Closed tenotomy is done by making two cuts through a patient's Achilles tendon at different levels and dorsiflexing his contracted foot strongly. This stretches his Achilles tendon, so that its fibres slide over one another. They rotate about 90[de] as they go down his leg, so you will have to make the two cuts in different directions, to allow for this.

Fig. 27-10 CLOSED ACHILLES TENOTOMY. A, if you don't have a tenotomy knife, make one by grinding away a No 11 blade. B, the two incisions. Make only tiny incisions in the skin. Insert the knife with its blade in the plane of the fibres, and then twist it before you cut. This shows the patient's left foot. The upper scalpel is being inserted from the medial side. C, put the patient's foot into a cast in gentle calcaneus. Kindly contributed by John Stewart.

LENGTHENING THE ACHILLES TENDON SERIAL CASTING INDICATIONS. Mild degrees of equinus deformity (see also Section 27.4). Flex the patient's knee as far as it will go. If this relaxes his calf muscles enough to let you bring his ankle into neutral (90[de]), you will be able to correct his deformity with casts. If both his legs are involved, correct them one at a time, or he will be confined to bed.

METHOD. Don't anaesthetize him. Apply a below-knee cast (81.5), while his knee is flexed to 90[de], to allow you to achieve more dorsiflexion of his ankle. You may not be able to get his foot into neutral on the first occasion.

When the cast is dry, apply a walking heel, and get him walking. Encourage him to progressively extend his knee as he walks. As soon as he is walking normally in his cast with his knee fully extended, repeat the procedure and apply a further cast, until his foot will reach the neutral position with his leg extended.

SUBCUTANEOUS ACHILLES TENOTOMY [s7]FOR POLIO INDICATIONS. See above and also Section 27.4. You can do the operation, if he also has a minor varus or valgus deformity, provided it is not so severe that it will prevent you fitting calipers. If necessary, you can release his ankle on the same occasion as his knee and his hip.

CONTRAINDICATIONS. If he is a child, tenotomy is contraindicated if: (1) His equinus ankle is helping to compensate for a short leg, or to stabilize an unstable knee, and so enabling him to walk satisfactorily. (2) He will never walk because his arms are weak. (3) His deformity is minimal, and he is managing well with a shoe or boot, with or without a caliper. (4) His feet are infected; if so, delay the operation. (5) He has a severe valgus or varus deformity which will make fitting a caliper impossible.

ANAESTHESIA. General anaesthesia, subarachnoid anaesthesia or ketamine.

METHOD. Use a small tenotomy knife, or the improvised one shown in Fig. 27-10. Use full sterile precautions, scrub up, gown yourself, use gloves, and apply a tourniquet (3.9).

To make the first incision, cut through the posterior two-thirds of his Achilles tendon, about 7 cm above its insertion. Do this by pushing the knife into the tendon from the medial side, in the line of its fibres, at the junction of the anterior third and the posterior two-thirds. Rotate the knife 90[de], and then cut posteriorly, until you feel the knife cutting very easily, which shows that you have now cut the posterior part of the tendon.

To make the second incision, push the knife into his tendon in the line of its fibres, at the junction of its lateral third and medial two-thirds, about 1 cm above the insertion of his Achilles tendon. Then, rotate the knife through 90[de], and cut medially, until you can feel the blade under his skin (these incisions cut all the fibres, at one level or the other, because of the way they rotate).

CAUTION ! (1) Use full sterile precautions, and drape him with sterile towels. (2) Use a gentle sawing motion, and don't break the blade. (3) Don't cut his posterior tibial vessels and nerves, which lie anteromedial to his Achilles tendon, as in Fig. 27-11. (4) Don't try to divide the tight posterior capsule of his ankle joint in this method. This is not tightened in poliomyelitis, unless there is an associated varus deformity, which must be corrected at open operation.

To manipulate his ankle, flex it dorsally. Apply force as close to the joint as possible. If you apply it at the end of his tibia, you can easily break it. In a young child with polio, you should be able to get 20[de] of dorsiflexion (calcaneus); in an adult or older child you may get less. If necessary, manipulate him again two weeks later.

If his ankle does not reach the neutral position (90[de]), check that his tendon has been divided properly, by reinserting the tenotomy knife in the same two tenotomy sites. If his ankle is still not fully corrected to 90[de][md]wait, and plan to increase correction by applying serial casts every 2 or 3 weeks.

POSTOPERATIVELY, squeeze out all subcutaneous clot. Bleeding is usually slight. Apply a small dressing.

If his knee is stable, apply a well-padded below- knee walking cast, with his foot near the maximum correction, but not at the extreme limit of extension. Elevate his leg, and send him home in a day or two. See a young child in 3 weeks, and an older child or adult in 6 weeks. Remove his cast and apply a below-knee caliper with a backstop.

If his knee is unstable and has no contracture, apply an above-knee cast. Treat him exactly as above, except fit an above-knee caliper instead of a below-knee one.

DIFFICULTIES WITH CLOSED TENOTOMY. [f41]If you have CUT HIS WHOLE ACHILLES TENDON by mistake, don't be alarmed. It will almost always heal satisfactorily in the lengthened position. Don't try to repair it.

If his DEFORMITY RECURS, it probably did so because he did not wear a caliper, or wore one without a backstop. If he does not wear one initially, his deformity is sure to recur. Six or 12 months later he may be able to do without a caliper. Follow him up carefully, so that you can decide about this.

If you FRACTURE HIS LOWER TIBIA because you have manipulated him too vigorously, fit him with a cast.

Fig. 27-11 OPEN ACHILLES TENOTOMY. A, the patient's left Achilles tendon exposed. B, the cuts in his tendon. C, his tendon lengthened. D, the anatomy of his ankle joint. E, if you have had to separate his tendon, bring its two halves together with mattress sutures. Note how the fibres of his tendon twist so that the medial ones come to lie posteriorly.

1, the saphenous nerve and vein. 2, tibialis anterior. 3, extensor hallucis longus. 4, the superficial peroneal nerve. 5, extensor digitorum longus and peroneus tertius in the inferior extensor retinaculum. 6, the dorsalis pedis vessels. 7, the deep peroneal nerve. 8, peroneus longus. 9, peroneus brevis.

OPEN ACHILLES TENOTOMY [s7]FOR POLIO INDICATIONS. Equinus contractures of the ankle, in which there is a contracture of the posterior capsule of the ankle joint that requires release. This is an alternative to the closed method.

METHOD. Give him a general anaesthetic, squeeze the blood out of his leg, and apply a tourniquet to his thigh (3.9). Place him on his side, with the leg to be operated on uppermost. Prepare his skin as usual.

Make a longitudinal incision over the lower third of his leg, extending proximally from the attachment of his Achilles tendon to his calcaneus.

Dissect out his Achilles tendon. You may see the small tendon of his plantaris on its anteromedial side. Make two incisions half way across his Achilles tendon: (1) The lower one 1 cm above its insertion, either from the medial to the lateral side, or vice versa. If there is any varus deformity of his foot leave the lateral side intact. If there is any valgus deformity, leave the medial side intact. The aim of doing this is to help the distal attachment of the tendon to correct the deformity. (2) At a suitable level, about 4 to 10 cm proximally (depending on his size and the degree of plantar flexion to be corrected), make a small incision opposite the first one, as in Fig. 27-11.

Then push up his foot. The fibres of his Achilles tendon will pull out. You should be able to put his foot into normal dorsi-plantar flexion, without too much force.

If you fail to put his foot into a satisfactory position, make a longitudinal incision down the middle of the tendon joining the two cuts. If this still does not correct the position of his foot, dissect down to the posterior aspect of his ankle joint, under direct vision. Divide the posterior capsule of his ankle joint transversely, from lateral to medial, and open up his ankle, by dorsiflexing the posterior part of his foot.

CAUTION ! Be careful not to cut: (1) his flexor hallucis longus tendon, or (2) his posterior tibial nerve and vessels, which lie on the medial side of the posterior aspect of his ankle joint. These structures are only in danger if you divide the posterior capsule.

If you have divided his tendo Achilles completely, bring its ends together with a mattress suture. Close his skin with 2/0 monofilament. Pad his leg, apply a below-knee cast with his knee flexed to 90[de], and release the tourniquet.

POSTOPERATIVELY, raise the foot of his bed, expose his leg on a pillow, and check the circulation in his toes hourly. Next day, add a ''shoe' to his cast. Discharge him on crutches, and check his cast in 3 weeks. Remove it or change it at 6 weeks.

Fig. 27-12 REHABILITATING CRIPPLED CHILDREN. With the kind permission of David Werner.