Tenotomy

Tenotomy is the cutting of the Achilles tendon in the back of the foot to correct the rigidity of the equines in a clubfoot. The tendon is cut and the foot is flexed and cast to encourage a lengthening of the tendon. The tendon will regenerate naturally and lengthen in three weeks, which is why the cast is left on for three weeks following a tenotomy.

The genius Dr Ponseti used his knowledge of the history of prisoners from the Second World War thus when the prisons ran out of space, prisoners were put in locations that had the sea on one side and mountains on the other. The tendons of prisoners were cut by the jail authorities who believed that they would never be able to escape by swimming or climbing the mountain. But they later realised that many prisoners escaped because the tendon regenerated naturally.

For children, a tenotomy is a very minor procedure that is easily carried out in the out-patient department or outside the operating room/theatre. Only local anaesthetic is administered and there is no requirement for stitches. Except for postural clubfoot, nearly every child requires a tenotomy. The tenotomy rate in any designated clubfoot clinic should be 90-95%. When tenotomy is not performed, the chances of recurrences are higher. Also, the Pirani score doesn’t come to zero because of the uncorrected rigidity of equines. So without tenotomy, the Ponseti method is neither complete nor successful.

How is the time for tenotomy determined?

Equines have to be corrected last after correcting cavus, addatus and varus. The Pirani score is the only simple way to determine the time for tenotomy. When the midfoot score is less than one and the hind foot score is more than one the foot is ready for tenotomy. Remember to note that the empty heel, talar head and the curved lateral border score should be zero before performing tenotomy. (As mentioned before, in the midfoot the medial crease may remain 0.5 since it takes time to disappear). In the hindfoot, the posterior crease score may remain 1 and the rigidity of equines is corrected only by tenotomy. So in the hindfoot score even when the score is more than 1 the child may undergo tenotomy.

However, it is important to note that all the six points come to zero after the tenotomy. If any point remains more than zero, additional casts are applied to bring the foot to zero Pirani score before applying the brace. In some children redoing tenotomy is also possible and done It is important to note that 70 degree abduction (external rotation) is genuinely required before the child is given a foot abduction brace. There is a misunderstanding among Ponseti practitioners that mild deformity could be corrected with a foot abduction brace. This is wrong. The pirani score has to be zero before applying a brace. In other words, the foot abduction brace is given to normal foot and not clubfoot.