The short answer
- Bone stress injuries happen to normal bone. The skeleton was fine; the rate of loading outpaced its ability to repair.
- Management is decided by location. Low-risk sites need graded loading. High-risk sites can need non-weight-bearing, medication or surgery.
- Low-risk tibial and metatarsal injuries are more than half of all bone stress injuries in runners.
- Loading is symptom-driven: at every stage the right dose produces no symptoms during, after, or the day following.
- In female runners, higher Triad risk scores carried more than four times the rate of bone stress injury in trabecular-rich bone. The cause is often energy, not mileage.
Two runners are told they have a stress fracture. One has it in the shin, the other in the neck of the femur. The first will load the leg carefully and run again in a couple of months. The second may need crutches, might need surgery, and is at real risk of a complication if anyone treats it like the first one.
Same words on the referral letter. Different injuries. Everything that follows depends on which one you have.
The bone was not weak
The mental picture most runners have is of a bone slowly wearing out. That is not what happens.
Two things follow from that. Bone is constantly repairing itself, and the injury is a repair process falling behind rather than a structure failing. And the skeleton in question is usually normal, which means the question worth answering is what changed in the loading or in the repair, not what is wrong with your bones.
Low risk and high risk are the real diagnosis
The single most useful sentence in the literature on this is that management is guided by location and the consequent risk of healing complications1. Sites are grouped by how well they heal, and the group decides the plan.
- Where
- Low-risk sitesPosteromedial tibial shaft, metatarsal shafts, fibula, pubic bone.
- High-risk sitesFemoral neck, anterior tibial shaft, tarsal navicular, fifth metatarsal.
- Why they differ
- Low-risk sitesHealing is reliable, and complication rates are among the lowest recorded.
- High-risk sitesComplication rates are the highest recorded, so healing can stall or fail.
- Usual management
- Low-risk sitesActivity modification, then progressive loading and return to running.
- High-risk sitesMay need non-weight-bearing immobilisation, medication, or surgery.
- Imaging before returning
- Low-risk sitesOften not needed to make the decision.
- High-risk sitesRadiological healing is expected before running resumes.
- Typical time back
- Low-risk sites44 days for the posteromedial tibia, 56 for the fibula.
- High-risk sites107 days for the femoral neck, 127 for the tarsal navicular.
The timings come from a meta-analysis of 76 studies covering 2974 bone stress injuries, which also found that more than 90 percent of athletes got back to sport, and that complications clustered in the femoral neck, tarsal navicular, anterior tibial shaft and fifth metatarsal2. The reassuring number and the cautionary one come from the same paper.
The low-risk group is also the common one. Tibial and metatarsal shaft injuries account for more than half of all bone stress injuries in runners3.
What loading actually means
For low-risk injuries, the default advice of six weeks off is both too vague and often wrong. There is a more precise rule.
Five consecutive pain-free days is a specific, checkable gate, and it is more useful than a date. The same review is careful about medication: analgesics or anti-inflammatories only in the short term, under seven days, and only for pain at rest or at night3. Taking something so you can run on it defeats the only feedback signal you have.
The tibial bone stress review reaches the same place from a different direction, listing resolution of bony tenderness, pain-free walking, and passed loading tests among the five things to have in place before running resumes4.
The mileage is rarely the whole answer
That is a large effect for something that has nothing to do with weekly kilometres. The IOC consensus statement on Relative Energy Deficiency in Sport describes the same underlying problem, intake that is too low relative to what training costs, producing health and performance consequences in both female and male athletes6.
The one mechanical lever worth pulling
Because bone responds to the number of loading cycles and their magnitude, there are two directions to work in. Reducing how many is the plan. Reducing how hard is the adjustment.
The bone literature suggests that when it is indicated, for example after repeated injuries, it is worth trying to reduce the magnitude of loading, and names increasing running cadence as the way to do it7. The low-risk management review makes a similar point, that optimal loading should continue after the return to running and may include jump training or gait retraining to reduce the risk of the next one3.
When to get it looked at
Diagnosis is made from history and examination, with imaging used to confirm it1. That means a good conversation and a careful hands-on exam get you most of the way, and the scan settles the question. It also means you do not need to wait until you have a scan booked to start acting sensibly.