Running 02 – Stress fractures in runners: a normal X-ray does not mean healed

The report from the foot scan has a single line of conclusion: no fracture seen. You fold the sheet in half, tuck it into a pocket of your backpack, and that same evening you lace up your shoes and head to the park again. The pain sits on the top of your foot, roughly between the second and third toes, and it began the week you started lengthening your weekend run to prepare for a new distance. At first it only stabbed in the last few kilometers. Little by little you felt it when standing at the stove for a long time, and some nights it still ached after you lay down. Running a finger along the top of your foot, you can find one exact point on the bone that makes you flinch when touched.

With a normal scan, can you keep running? With this kind of pain, usually not yet. In the first weeks of a stress fracture, X-rays are often still clear while the bone is already injured. Runners often stumble on exactly that gap between the film and the real bone, because they trust the sheet of paper more than the painful point under their own fingertip.

Dripping water wears away stone

A stress fracture does not need a fall. It comes from thousands of footsteps landing on the same stretch of bone, run after run, when the load rises faster than the bone can cope with. Sports injury textbooks call it a bone stress injury, that is, an injury caused by force applied over and over (bone stress injury, abbreviated BSI); runners usually call it a stress fracture.

Our grandparents said “dripping water wears away stone” to praise people who persevere. In running, the saying is true in the literal sense too: small steps, repeated long enough, can wear down a weak spot in the bone. The difference is that bone is alive. Given rest at the right time, the bone heals; keep running and the wear goes deeper.

Both men and women can get it. A review by Hollander and colleagues (2021) found that the total number of running injuries was about the same in both sexes, but for bone stress injuries the risk in men was only about half that in women.

The report says “not seen”

An X-ray can show a bone injury once it is clear enough. With a stress fracture, the film is often still normal in the first weeks; magnetic resonance imaging (MRI) is the most sensitive way to see an early injury (Joyce and Lewindon, 2016; Magee and Manske; Travell and Simons). So a report saying “no fracture seen” in the second or third week only tells you the film has not shown it yet. That sheet of paper says nothing about whether the bone has healed.

You also don’t need to wait for imaging before you stop. Pain focused on one point on a bone, pain when you press on that exact point, and then each run hurting more than the last, or the pain following you into rest and into the night: the textbooks on injuries and on musculoskeletal imaging consider that enough to stop running and see a doctor. What to scan, and when, is for the doctor to decide after examining you.

While you wait, don’t take anti-inflammatory painkillers to get through your runs; when a stress fracture is suspected, this group of drugs should be avoided (Joyce and Lewindon, 2016). We remind ourselves of something similar: a batch of herbal medicine, an acupuncture session or a correction session that makes you feel better does not mean the bone has knitted. Feeling better early and rushing back to running can mean running on the very spot where the bone is still injured.

One point, or a whole stretch

In the lower leg, a stress fracture is often confused with medial tibial stress syndrome (MTSS), which runners know as “shin splints”, one of the most common injuries in runners (Videbæk and colleagues, 2015). The easy difference to remember is how much area hurts. MTSS pain spreads along the lower two-thirds of the inner edge of the shinbone, and you can feel a whole long stretch that is tender. A stress fracture hurts at one point. Both kinds of pain can be on the same bone, so telling them apart needs a doctor to examine you in person.

Where bone heals poorly

Joyce and Lewindon divide stress fracture sites into two groups by how well they heal. The high-risk group, which heals poorly and is prone to complications, includes:

• The femoral neck on its upper outer side, where the bone is under tension;
• The kneecap (patella);
• The anterior cortex of the tibia, that is, the front of the shin;
• The sesamoids, two small bones under the base of the big toe;
• The navicular, on the inner side, in the middle of the foot;
• The neck of the talus and the medial malleolus (the inner ankle bone);
• The 5th metatarsal, on the outer edge of the foot.

Stress fractures in this group need follow-up by an orthopedic and trauma specialist. You return to running only when imaging confirms the bone has healed; being free of pain is not enough.

The most worrying is the femoral neck. The pain is usually in the hip or groin, and becomes clearer when you put your weight on the leg, when you hop on one leg, or when the heel is tapped. Magee’s textbook on musculoskeletal examination and Egol’s handbook of fractures treat this as the most important warning sign in female runners and long-distance runners, needing an early MRI. This pain is easily taken for a strained groin muscle, which is why it is so often overlooked.

The low-risk group includes the shaft of the femur, the fibula, the inner side of the tibia, the heel bone (calcaneus) and the 1st to 4th metatarsals. In this group, the return plan can be counted from the number of pain-free days, as in the next section. The painful spot in the opening scene, between the second and third toes, most likely belongs to this group, but the doctor still has to identify exactly which bone first.

Pain-free for a while, then running at half effort

For a low-risk stress fracture, once it has been diagnosed, there is a step-by-step approach recorded by Joyce and Lewindon (2016):

• Stop running, take relative rest, and keep up your heart and lung fitness with activities that put little force through the bone, such as cycling and swimming;
• Wait until you have been pain-free for 10–14 days;
• Return to running at half your previous intensity;
• Increase by 25% at each step, with the whole plan spread over 3–6 weeks;
• Do not increase every day.

Going this slowly gives the bone time to catch up. On the way back, if the pain returns to the same old point, the clinic advises stopping at the step you are on and telling the doctor, rather than pushing on to the next step.

This plan is expert experience recorded in a textbook. So far no study has established how long the return to running should take after a stress fracture in runners, and according to the two authors themselves, shockwave therapy and pulsed ultrasound do not yet have enough evidence to shorten that time either. High-risk stress fractures do not follow this schedule; they follow the specialist and the imaging.

The second fracture in two years

Among the factors studied in recreational runners, an injury in the previous 12 months is the most consistent predictor of a new injury (Saragiotto and colleagues, 2014). Someone who has had one stress fracture therefore needs to ask carefully why it happened, rather than just waiting for the pain to go.

The first question is usually whether you are eating enough. When the body is not fed enough for the amount of training, bone is one of the places that loses out. The International Olympic Committee consensus on relative energy deficiency in sport (RED-S; Mountjoy and colleagues, 2023) lists stress fractures among the main signs of this condition when one of three situations applies:

• One stress fracture in a bone with a lot of spongy inner structure (trabecular bone), such as the femoral neck, the pelvis or the sacrum;
• Two or more stress fractures at other sites within 2 years;
• Having to stop training for 6 months or more because of a stress fracture.

These often come with weight loss; in women, infrequent periods (cycles longer than 35 days) or periods that have stopped for 3 cycles or more; in men, lower sex drive and low testosterone. No single test confirms RED-S. In cross-country runners, the factors of RED-S are linked to stress fractures with a moderate level of evidence, meaning fairly reliable but not yet certain (Joachim and colleagues, 2024). For women, cycles that keep stretching out during a heavy training season are worth getting checked early, and if you are trying to conceive, all the more reason not to wait.

One habit does not help the bone as much as many people think: dynamic stretching before a run does not reduce stress fractures of the tibia (Lavigne and colleagues, 2023). What helps is still increasing the load gradually, and that includes the times you change shoes, change running surface or move onto trails.

The tub of calcium on the kitchen shelf

The trial mentioned most often is the one by Lappe and colleagues (2008). In it, 5,201 female navy recruits were randomly divided: one group took 2,000 mg of calcium with 800 IU of vitamin D (international units, the way vitamin D doses are written on labels) every day during 8 weeks of training, and the other group served as controls. Stress fractures occurred in 5.3% of the group taking the supplements and 6.6% of the control group, meaning the number of stress fractures fell by about one fifth compared with the control group.

Recruits in a training camp, however, are very different from recreational runners. Applying those results to civilian runners, men or middle-aged people is an inference; there is no separate trial for them yet.

For athletes who are not eating enough energy or who have menstrual disorders, the International Olympic Committee (Maughan and colleagues, 2018) suggests 1,500 mg of calcium together with 1,500–2,000 IU of vitamin D a day; anyone deficient in vitamin D takes a treatment dose based on lab tests. The safe upper limits according to the US National Institutes of Health (NIH) are 4,000 IU of vitamin D and 2,000–2,500 mg of calcium a day. Taking more does not make bones stronger either: in the trial by Burt and colleagues (2019), the group taking 10,000 IU of vitamin D a day for 3 years actually lost the most bone density.

Before you buy a tub of calcium or a bottle of high-dose vitamin D because your running group talked you into it, let the doctor ask about your meals, ask women about their menstrual cycle, and order a blood vitamin D level when needed.

What the thigh muscles say about the bone

Once you have been cleared to run again, the Applied Kinesiology (AK) examination for someone who has had a stress fracture revolves around one question: does the body have enough of the minerals and vitamins that bone needs? Walther’s muscle charts give the doctor a place to start. For the quadriceps at the front of the thigh, he lists vitamin D; cramps in the hamstrings suggest looking at calcium needs. Calcium also goes together with B vitamins for the peroneal group, the muscles running along the outer side of the lower leg that keep the ankle from rolling (Synopsis, p. 311, 313, 332–333).

Suppose that when tested, the quadriceps is working below threshold (when tested by hand, the muscle cannot hold as much force as normal) in both legs. You hold a little vitamin D on the tip of your tongue for a few seconds, and then the muscle is retested. If the muscle holds firm, that is a hint to look further into vitamin D; if it still gives way, the doctor looks in another direction. The test cannot set a dose, so the doctor still places it alongside your blood vitamin D result and your diet before discussing any supplement. For women, Cuthbert notes that long-distance runners with irregular periods often lack calcium and many other nutrients in their diet, so the bone gradually loses density and then a stress fracture follows (p. 177); that is why muscle testing always comes with questions about the menstrual cycle.

In the foot, Cuthbert notes that stress fractures often fall in the middle of the shafts of the 2nd and 3rd metatarsals, where bending forces are greatest in long-distance running, and that people with a low longitudinal arch (flat feet) are more prone to fractures in the forefoot (p. 176), exactly the area of pain in the opening scene. He also cautions: with injuries in the talus or the bones of the midfoot that are hard to see on X-rays, pain that increases with activity and then aches even at rest, and that does not improve with routine AK treatment, is the kind of pain that calls for a bone scan, an imaging method that uses a tracer to show injured bone that X-rays have trouble seeing (p. 176).

The Kidney governs the bones

In traditional medicine theory, the Kidney governs the bones (肾主骨 / 腎主骨, shèn zhǔ gǔ), meaning bone belongs to the Kidney, and the Kidney “governs the two legs”, watching over both legs. The Liver governs the sinews (肝主筋, gān zhǔ jīn), meaning the Liver organ oversees the tendons and muscles, and the books call it “the root of enduring fatigue” (罢极之本 / 罷極之本, pí jí zhī běn), the source of the capacity to bear hard work. The traditional healer (lương y) Nguyen Huu Duc teaches that illness in the two legs tends to point toward the Kidney, and that a worsening gait is an early sign that the Kidney qi and the Kidney’s physical form (the function and the physical substance of the Kidney organ) are declining.

Someone already diagnosed with a low-risk stress fracture and following the plan above, who also has aching lower back and knees, legs that feel weak on long runs, and pain that gets worse with exertion, may be classed in traditional medicine under the pattern of Liver and Kidney deficiency with weak bones (肝肾虚、骨弱 / 肝腎虛、骨弱, gān shèn xū, gǔ ruò). After the examination, the doctor may prescribe a decoction in ready-to-drink 50 ml pouches for this pattern, cooked separately for each person, aimed at supplementing the Liver and Kidney and strengthening the sinews and bones, with herbs such as Sang ji sheng (Taxillus chinensis stem and leaf), Du zhong (Eucommia ulmoides bark), Xu duan (Dipsacus asper root) and Niu xi (Achyranthes bidentata root). For people who are pregnant or trying to conceive, Niu xi is left out, while Du zhong and Sang ji sheng are kept.

The pouches only go alongside; they cannot replace anything in the sections above. There is currently no evidence that the medicine makes bone heal faster; all we have so far are the classics and animal experiments. The day you return to running is still counted from the day the pain went and from the imaging, not from the number of batches of medicine you have taken.

When to come in for an examination

If the pain at one point on the top of your foot gets worse run after run and follows you into the night, the folded sheet of paper in your backpack is not enough to keep running. Put your shoes aside, get examined again, bring the scans you have had, and tell the doctor everything: which week the pain started, how your weekly distance has increased, whether you have ever had a stress fracture before, and for women, your menstrual cycle over the last few months. If it really is a stress fracture of a low-risk metatarsal, your return plan is counted in weeks.

Someone who has had a stress fracture without knowing why, or who is following a return plan, should also come in to review diet, training load and the leg muscles. At the appointment, Dr. Dinh Ngoc Duc (MD, MSc in Traditional Medicine) looks at your previous scans together with the painful spot, and decides whether more imaging or a referral to an orthopedic and trauma doctor is needed; herbal decoctions and a training schedule are only considered once it is clear which bone and which group. Book a consultation.

A pair of running shoes left in the corner for a few weeks comes to no harm. The bone on the top of your foot gets time to knit, and the next time you lace up, you start at half effort.

Worth keeping

• Pain focused on one point on a bone, tender to press, getting worse run after run or hurting at night: stop running, even if the X-ray is normal;
• Hip or groin pain when putting weight on the leg or hopping on one leg: get examined right away and ask the doctor about an MRI;
• If a stress fracture is suspected, do not take anti-inflammatory painkillers to get through your runs;
• Low-risk stress fracture: wait until you have been pain-free for 10–14 days before running again at half intensity, increase by 25% at each step, and do not increase every day;
• Stress fractures of the femoral neck, kneecap, front of the tibia, navicular or 5th metatarsal: return to running only when imaging confirms healing;
• A second stress fracture within 2 years, or periods becoming infrequent when you train a lot: get checked for diet and energy;
• Ask the doctor for a vitamin D test before buying high-dose tablets on your own.

References

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