Stress Fractures in Athletes* M

SPORTS MEDICINE VIl Stress fractures in athletes* M. B. DEVAS, F.R.C.S. Bexhill-on-Sea A STRESS fracture may be defined as that fracture which occurs in the normal bone of a normal individual undergoing normal activity and with no injury. To under- stand stress fractures, or as they are sometimes called, fatigue fractures, it must be understood that the normal bone of a healthy individual is very much alive and that it is in no way comparable to a concrete post but it is much more like a piece of living wood. However, in certain respects bone differs from other material to which it might be compared in that it has the ability to restrengthen itself after it has become weakened by use. During use bone absorbs energy; were the bone to be made of metal or concrete it would break in due course of use. But bone, being alive with a free flowing blood supply, normally does not break but continuously regains its lost strength. Athletes, usually in the full vigour of youth, are essentially fit and do not have abnormalities or disturbances of metabolism but they can, by over-exercising especially when not in training, lay themselves open to an increased incidence of stress fractures. Thus a marathon runner in full training will be less likely to develop a stress fracture at, say, the twentieth mile than another who is out of training. Thus training counts even in avoiding stress fracture, because bone will become strdnger by being used, in exactly the opposite way that it becomes weak with immobilization in plaster. Athletes are not the only people to sustain stress fractures and, using the tibia as an example, out of every 100 stress fractures approximately 36 occur in athletes at about 18 years of age; 23 occur in children of whom some are athletic but not all; and the rest occur in older people, with the exception of a small number in ballet dancers. Types of stress fracture In the main, there are two types; one in which the bone is compressed (figure 1) and one in which the bone is bent and thus breaks (figure 2). It is important to emphasize that all stress fractures are caused by muscular activity, or pull, on the bone and they are not caused by heavy footfalls in running or when jumping jars the bone. Diagnosis of stress fractures The classical symptoms caused by a stress fracture are that, first, the athlete complains of pain towards the end of his sport, or shortly afterwards, which is described as "a bit of an ache", or "a little nagging pain", but to begin with it is not severe and it does not cause him to seek attention. However, with the continued practice of the sport the pain begins to become not only more severe but also to occur earlier during the sport; it lasts longer and sometimes disturbs sleep. However, next morning the athlete feels better and may be encouraged to start running again only to find that after a short while the pain comes on severely and, although the activity is stopped, the pain remains. Advice is sought and perhaps a week's rest is advised. At the end of that time the pain has gone completely with ordinary activity but as soon as the athlete returns to sport the pain comes on again with renewed emphasis. This pattern of coming on, resting, *Reproduced by kind permission of the Academic Board of the Institute of Sports Medicine. J. ROY. COLL. GEN. PRACTIT., 1970, 19, 34 STRESS FRACTURES IN ATHLETES ,35 getting rid of the pain, returning to sport and further pain may be repeated to the detri- ment of the athlete throughout the season. The history of the pain is all important because physical signs are not always easily found. In the fibula it is possible, on occasion, to see a little swelling ifthe stress fracture is in its lowest third (figure 3). However, this particular bone does allow palpation at that area and a swelling may be felt on the bone; it is hard, being ofcallus or pre-callus, and is fusiform and tender. Springing the fibula from above may cause pain at the Internal callus Oblique crack in one cortex., External callus Figure 1. Figure 2. Diagram of a compression stress fracture. Diagram of the oblique stress fracture common to athletes caused by bending of the bone. fracture site. In the tibia, with 'shin soreness' in runners, there is again local tenderness and a little local swelling may be felt but, in the early stages, swelling of the bone is rare. In any other part affected tenderness will be present but usually it is difficult to elicit accurately because most bones are well covered with muscles. The stress fracture of the metatarsal bone which often occurs in athletes can, of course, be felt in much the same way as the fibula. Oblique crack becomes complete. Oblique crack in one cortex only. Figure 3. Figure 4. Diagram of a stress fracture of the lower third Oblioue stress fracture of the tibia which is the of the fibula. No.te that there is soft tissue cause of shin soreness. Note that the fracture swelling just visible above the lateral malleolus. in the lower part of the tibia runs upwards and inwards through one cortex only. 36 M. B. DEvAs Radiographs are notoriously slow in revealing a stress fracture and up to three months can elapse in certain fractures before confirmation is seen radiologically. Mean- while, any form of blood test or other pathological investigation will come back with a normal result. Treatment This is basically simple but not always easy to carry out. Absolute rest of the part to the extent of not developing the pain must be ensured. Thus the weekend amateur athlete may be allowed to continue his work as a bank clerk provided he takes no exercise. If, however, even this work causes pain, then he must rest at home. Elastic adhesive strapping gives support to the leg and shows the athlete that treatment is being given. But, above all, it is rest which must be prolonged to suit the time for each fracture to unite that cures the lesion. A stress fracture of the tibia may take four to six weeks and occasionally longer before it is united so firmly that training can start with impunity. When there is clinical evidence, through lack of tenderness at the fracture site, that the fracture has united, the athlete is allowed to return to gentle training under careful supervision; provided this does not cause any recurrence of symptoms, training is increased. It is however, very important to allow the bone time to become strong for the particular muscular activity before it is subjected to complete stress, such as a race or a match. The common types of stress fracture in athletes Thefibula The lowermost third of the fibula is the most common site for a stress fracture in athletes and is often known as the runner's fracture. The history is typical of a stress fracture as has been given above and, at this particular site, the clinician is fortunate to be able to feel the bone underneath the skin and the fusiform swelling at the fracture site Transverse crack goes completely across tibia. Figure 5. A transverse stress fracture shown diagranunatically in the centre of the tibia such as occurs in a ballet dancer. This fracture readily becomes complete with continued activity. can be felt; very rarely it can also be seen. Springing the fibula by pressing upon its shaft above the site of the pain may cause pain at the fracture site. Radiographs will show initially a small oblique crack in the outer cortex of the fibula, running upwards STRESS FRACTURES IN ATHLETES 37 and inwards, about five centimetres above the tip of the lateral malleolus. After a further period of time radiographs will show that the fracture has progressed and gone right across the fibula shaft and that callus is present all round. This is not always the case and, if an athlete stops running as soon as he gets the pain in the lower part of the fibula, the fracture may not progress across the whole of the shaft but may stay confined to the lateral cortex only. The treatment is standard; rest from pain-producing activity and elastic adhesive strapping. Usually the athlete is able to start training, under observation and with care, four to six weeks after treatment has started. Metatarsal bones A march fracture occurs in athletes as it does in others and is fairly easily recognized by pain localized to the shaft of one or other metatarsal bones. In this respect, the base of the fifth metatarsal bone can also sustain stress fractures. The first metatarsal bone appears to be exempt in athletes. The radiographs will show the fracture usually to be in the metatarsal neck although occasionally the base of the bone has the fracture. The pattern is similar to that in the fibula in that the fracture rapidly becomes complete across both cortices of the metatarsal shaft. Again, however, if the onset of pain coin- cides with the cessation of activity the whole of the bone may not break. Rest with supportive bandaging is sufficient to allow healing in four to six weeks but a special note of warning is needed for those stress fractures that occur at the base of the fifth metatarsal bone because here the pull of the tendons may distract the fracture to give a small gap and union can take a long time.

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