Atypical femoral fracture
Also called: AFF
What it means
An atypical femoral fracture is an uncommon break in the shaft of the thigh bone that looks and behaves differently from a typical fragility fracture.
Knowing this term helps you understand why your prescriber may discuss monitoring if you're on long-term bone medication.
An atypical femoral fracture is a rare break in the thigh bone that behaves differently from a typical fragility fracture. Instead of happening at the hip, it occurs along the shaft of the femur and tends to break in a straight, horizontal line rather than the jagged pattern seen in most bone fractures. This distinct pattern is part of why doctors classify it separately from a usual hip fracture.
These fractures fall into a category sometimes linked with medications that slow down bone remodeling, since the whole point of remodeling is to clear out old, worn bone and replace it with fresh bone. If that process is overly suppressed for a long stretch of time, bone in certain spots may not get the normal renewal it needs. Any questions or concerns about a specific medication and how it affects your bones should be discussed with your prescriber, who can weigh the full picture of your treatment.
If you're on a long-term bone medication, your prescriber may talk with you about monitoring and periodic reassessment as part of routine care. This isn't something to self-manage or guess about — it's a conversation to have with the doctor overseeing your treatment, who can consider your full history and the role your medication plays in your overall bone health.
How sure is this?
Graded Established Science: Supported by broad scientific consensus and decades of research. Read each study with its grade in mind. One study is a piece of the picture, not the whole of it.
This rare thigh-bone break behaves differently from a typical fragility fracture and may prompt monitoring on long-term bone medication.
Where this leads
WordCurious which medications come with this rare monitoring conversation? See how bisphosphonates work and why your prescriber keeps an eye on things.
Where the Academy teaches it
This page is the short version. The lessons teach it in full, with the context around it and a quiz to lock it in.
Related words
The femoral neck is the angled part of bone joining your hip ball to your thigh bone shaft, and it's the most common…
A hip fracture is a break at the femoral neck, the narrow part of bone connecting the hip joint ball to the thigh…
A fragility fracture is a broken bone caused by a fall or bump that normally wouldn't break a healthy bone, often at…
Bisphosphonates are osteoporosis medications — like alendronate, risedronate, and zoledronic acid — that slow down…
Bone remodeling is the lifelong cycle where cells called osteoclasts remove old bone and osteoblasts build new bone…
A drug holiday is a temporary, prescriber-guided pause from a bisphosphonate medication after several years of use,…
The femoral shaft is the long middle part of the thighbone (femur), connecting the hip end to the knee end.
Ibandronate is a bisphosphonate drug, sold as Boniva, used to treat osteoporosis by slowing the breakdown of bone.
Education only, not medical advice. Decisions about tests, medications and treatment belong with your own doctor. OsteoStrong does not diagnose, treat or cure any disease.
