Achilles tendonitis, probably best termed Achilles tendinopathy, this is a degenerative condition in the substance of the heel tendon. It is very common indeed and probably affects 10% of distance runners per year. There are a number of factors which predispose to this, but there is a major design fault in the tendon which is the reason why problems are so common. We often see problems in musculotendinous units which traverse two joints and the Achilles is one of the commoner ones (in fact the Achilles tendon actually spans three joints – knee ankle and sub-talar). There are two muscle bellies which attach to the tendon before it goes down and attaches to the heel and one of them attaches above the knee, one below. This means that as you are running and you straighten out your knee it will pull on the muscle which pulls on the Achilles tendon which pulls the heel up giving you more power to push off. As you are pushing off your thigh muscles, which straighten out your knee, can also be used to transmit force to increase the push off from your toes. This means that the Achilles tendon and its musculotendinous unit can stay at more or less the same length and simply transmit muscle from the thigh to the toes. It also means that it often works eccentrically, that is instead of the muscle contracting and pulling the toes down, it is often used as a shock absorber and “pays out” line as the heel comes down towards the ground. This eccentric contraction of the muscle puts enormous forces across the musculotendinous unit. Because three joints are spanned, any rehabilitation exercise may need to be done with the knee and foot in various positions for maximum effect.
The Achilles tendon has a very high proportion of elastin fibres which are used as shock absorbers and the tendon also has about a 90 degree twist along its length. This means that as it is contracting and relaxing, a significant shearing force can develop, which can lead to quite a lot of heat in the tendon. The tendon also has rather a poor blood supply and all of this contributes to the commonness of Achilles tendinopathy. Not much of the above “design fault” is treatable, but one of the things which we can address in treating, and hopefully preventing Achilles tendon problems, is over-pronation. Pronation, which is similar to flat foot, is a description of an abnormal side to side angulation of the heel during the gait cycle. Everyone runs with a tendency to land with the heel pointing inwards a little bit and then the impact of “heel-strike” is absorbed by the foot rolling inwards & the heel rolling outwards and the arch of the foot collapsing just a little. As you push off the toes at the end of the stance phase this arch is re-created.
In runners who over pronate this movement is excessive which means that the heel is waggling back and forth, throwing enormous stresses across the poor Achilles tendon which is attached to it. This can be corrected by an orthosis, either an off the shelf insole or preferably a custom made orthosis.
Achilles tendonopathy is best treated by a period of relative rest, perhaps a bit of a heel raise to take the strain off as well as the orthosis, and by some local physiotherapy modalities. One of the exercises which has been shown to be of considerable benefit is actually eccentric training despite the comments above on eccentric contraction being implicated in the cause of the disorder. A high proportion of patients with Achilles tendonopathy will be helped by pursuing a course of exercises which involve standing on a step, going up onto tip toes using both legs and then taking all the weight through the bad leg before lowering down slowly. This should be fifteen times and three sets a day. It should be uncomfortable, but not painful. When it ceases to become uncomfortable you can wear a rucksack and put a bit of weight through it and continuing with this course of exercise for a total of three months will lead to resolution of the symptoms in a majority of patients. See: H. Alfredson, T. Pietila, and R. Lorentzon. Chronic Achilles tendinitis and calf muscle strength. Am.J.Sports Med. 24 (6):829-833, 1996.
Injections are generally to be avoided, especially steroids, but there are a number of new treatments - especially platelet rich plasma & volume injections (aimed at dealing with peritenidinous neovascularisation) which are showing promise.
Extracorporeal shock wave therapy is a very effective and safe new treatment for certain tendonopathies, but requires rather expensive & specialised equipment. We now have access to this routinely and are starting to see the benefits.
Apart from exercises under the supervision of an expert physiotherapists, there is some evidence for the beneficial effects of GTN (angina) patches out directly onto the painful area daily. This is an unlicensed indication for the drug, but has few side effects. The regime is for one quarter of a patch daily for several weeks. See: Angina patches for tendinopathy. Paoloni JA. Appleyard RC. Nelson J. Murrell GA. Topical glyceryl trinitrate treatment of chronic noninsertional achilles tendinopathy. A randomized, double-blind, placebo-controlled trial.[see comment]. [Clinical Trial. Journal Article. Randomized Controlled Trial] Journal of Bone & Joint Surgery - American Volume. 86-A(5):916-22, 2004 May.
Achilles tendonopathy is commonly divided into insertional and non insertional, that is whether the discomfort is right at the heel bone or within the body of the tendon just above it and I am afraid the insertional problems are much less commonly treated successfully without operation. There is often a spur of bone at the back which needs to be removed in order to have it settle. Overall my results for surgery on Achilles tendon are that about 85% of patients have good and excellent results at more than six months post operatively, but it is not a quick fix. The surgery simply allows nature to get on top of the problem and it is, therefore, very important that the best conservative measures are followed first under the supervision of an expert physiotherapist.
Achilles tendon ruptures seem to be a different problem and although not uncommon and a real “pain in the neck” injury to have, runners who have Achilles tendonopathy do not seem to be the same group of patients who have a rupture. The rupture usually occurs out of the blue playing badminton or squash in a man in his forties. He thinks his opponent has hit him on the back of the heel with his racquet, and turns round to protest before falling over. There is considerable debate about whether complete ruptures of Achilles tendon should be treated with repair or rest in a plaster cast and there are arguments both ways.
I usually counsel patients that there is very little difference in the outcome if everything goes smoothly, but there is a reported rate of complications of surgery of 10-15%, particularly poor wound healing. There is also however about a 10% risk of re-rupture after treatment in plaster, so there are problems with or without surgical repair. It is possible that the endurance strength of a repaired Achilles tendon is a little bit better in the long term, but the evidence of this really is not very strong and I tend to leave it up to the patient to decide. I would really recommend non-operative treatment in the rather older age group and in patients who come to see me straight away so that there is not a big gap in the tendon palpable. If there has been any delay or in young and high demand sportsmen then I tend to recommend surgical repair.