Stress fractures can occur in almost any bone in the body. Metatarsal, fibular, and tibial stress fractures are the obviously common ones in runners, but many wannabe marathoners who present with groin or SIJ area pain receive an incorrect or vague diagnosis, when they might be suffering from a pelvic or sacral ala stress fracture. Femoral neck fractures are particularly serious, and so how can we ensure that we don’t miss them?
Persistent or intermittent pain which is worse with weight bearing and sometimes present at night, equals a stress fracture until proven otherwise. Beware particularly of the patient who states that it was ‘so painful’ that they ‘were finding it difficult to walk’, although it doesn’t have to be this extreme. Femoral and pelvic stress fractures may often have quite a ‘woolly’ presentation from a symptomatic point of view, and it may be very difficult to find any convincingly positive clinical examination findings, despite the fact that the patient’s in pain. It helps if you can conceptualise that a ‘woolly’ presentation is, in itself, a warning sign of a possible stress fracture. A helpful question to ask patients is whether they can sense the discomfort when they rapidly transfer their weight from one leg to another. If they’re pain free when hopping, it makes a stress fracture less likely.
Probably one of the key things which further muddies the waters, or may throw people off the diagnostic path, is imaging. X-ray imaging will nearly always fail to spot a stress fracture, and should not be used as a screening tool, and MRI (which demonstrates bony oedema, and a periosteal reaction with or without an actual fracture line) is the investigation of choice. If access to MRI is impossible, either because of availability or for financial reasons, you may need to decide to go ahead and treat the injury as if it were a fracture.
Let’s say you’ve spotted the possibility of a bony stress injury, which has been confirmed through MRI imaging.
So what next?
The treatment is typically to offload the area for a period of time, and this may mean complete non-weight bearing on the affected side for six weeks, as in the case of a femoral neck fracture. Treatment for a navicular fracture, is typically non-weight bearing with crutches, and immobilisation in a rigid boot, also for six weeks.
Often runners can be permitted to continue some level of cardiovascular training, such as swimming with a pull buoy, provided they are pain free. At the end of that period of time, most clinicians will choose to assess healing clinically, looking for the absence of tenderness, and an ability of the patient to perform functional activities without pain. If you have a patient who remains in pain despite offloading, this would be a reason to re-image them. Fractures that have a high potential risk of non or poor union (such navicular stress fractures) probably deserve a follow up MRI to check for adequate healing prior to the patient getting back on both feet.
The next stage is to re-strengthen our patients, and return them gradually to their normal activities – this shouldn’t be rushed. This is the hard part, as some patients having been freed from the slavery of crutches decide that waiting any longer is too much to bear. Getting rehab ‘buy-in’ from them during this ‘parole’ period is essential if they want to avoid wearing the (oh so last season) Stormtrooper boot for a second time around.
As well as addressing metabolic issues (such as poor energy balance secondary to a low calorie diet), it is important to correct any biomechanical faults. To run well, the body’s biomechanical chain has to be capable of appropriately absorbing ground impact forces. Optimally firing glutes and a strong posterior chain are very important for lumbopelvic stability. A runner who has dysfunction of soleus, tibialis anterior, or tibialis posterior, will experience a ‘tug of war’ in forces across the lower leg, encouraging excessive tibial and fibular torsional and compression forces. Foot wear, running surfaces, an opinion from a sports podiatrist, and training schedules all need consideration, and it’s important to get across the message to runners that they need to commit to regular conditioning work, in addition to just running.
Increasingly there is school of thought that we should carry out screening bloods on our patients to correct deficiencies, which may delay recovery (e.g. checking for vitamin D), but also to screen for medical conditions which can predispose to fracture (such as renal and thyroid dysfunction). DEXA scanning is a widely available an inexpensive way of assessing current bone mineral density, and we would encourage its use to assess a baseline for all athletes who have sustained a stress fracture. If a patient undergoes DEXA scanning and is found to have osteopenia (which is a T score falling between -1 to -2.5 standard deviations below the mean) or osteoporosis (T score -2.5 or below standard deviations), then they should be referred for specialist opinion to a sports physician or rheumatologist with an interest in this area.
So the take home messages are: stress fractures are surprisingly common, and may present in a ‘woolly’ fashion, with not much to find on clinical examination. Have a high index of suspicion when patients describe awareness of night time discomfort, or have had pain weight bearing. Remember that x-rays can’t rule out stress fractures, MRI is the investigation of choice, so refer EARLY for an opinion or scan. Finally, we need to correct biomechanical and strength deficiencies, and make an assessment of nutritional, metabolic, and bone health to ensure our patients recover and remain well in the long run.
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