Transient Osteoporosis

For Medical Students

What It Shows

Transient osteoporosis is regional bone loss with marrow change that resolves without treatment. 5.13.1 covers bone marrow oedema.

It appears as diffuse marrow change across a whole bone end, with no fracture line and no geographic margin. 5.2.17 covers the STIR imaging.

It matters because it is diagnosed in retrospect, so naming it on the first scan is a guess dressed as a diagnosis. 5.1.6 covers imaging pitfalls.

How It Is Acquired

Image the whole affected bone end with fluid sensitive and T1 weighted sequences. 5.2.16 covers the fat suppression.

Confirm there is no fracture line inside the change. 5.13.3 covers stress fractures.

Confirm there is no geographic margin. 5.13.5 covers osteonecrosis.

Confirm the cortex is intact and there is no soft tissue mass. 5.13.7 covers bone tumours.

Plan the interval scan when the first one is reported, because the interval is the test. 5.20.1 covers structured reporting.

What Normal Looks Like

Marrow following fat throughout the bone end. 5.5.6 covers the bones.

No line and no margin inside any change. 5.13.3 covers stress fractures.

An intact cortex with no periosteal reaction. 5.3.2 covers the lateral view.

Resolution on the interval scan, which is what confirms the diagnosis. 5.20.1 covers structured reporting.

What Abnormal Looks Like

Diffuse marrow change crossing a whole bone end rather than one compartment. 5.13.1 covers bone marrow oedema.

No fracture line and no margin inside it. 5.13.5 covers osteonecrosis.

Reduced bone density on the radiograph in the same region. 5.3.1 covers the AP view.

A joint effusion with no structural cause. 4.3.8 covers swelling.

Change that has not resolved on the interval scan, which removes the diagnosis. 5.13.3 covers stress fractures.

MRCS Level

How It Is Acquired

In a viva the expected answer refuses to make the diagnosis on one scan.

The expected points are the whole bone end, the absence of a line, the absence of a margin, the intact cortex, and the planned interval.

Say that the diagnosis is retrospective by definition. 5.1.6 covers imaging pitfalls.

Say that a fracture and a tumour have to be excluded before waiting. 5.13.7 covers bone tumours.

Say that the report's job here is to state what it is not. 5.20.1 covers structured reporting.

What Abnormal Looks Like

The reasoning expected is that several conditions share this appearance and differ only in what happens next, which makes time the discriminating test rather than any sequence. 5.13.1 covers bone marrow oedema.

A fracture line or a geographic margin rules the diagnosis out at once, so the search for them is the whole of the first read. 5.13.5 covers osteonecrosis.

Cortical destruction or a soft tissue mass makes waiting unsafe, which is why it is excluded before any interval is offered. 5.13.7 covers bone tumours.

The condition occurs in settings where a systemic cause is likely, so the history carries weight the images cannot. 4.2.14 covers the inflammatory pain.

How Good It Is

Magnetic resonance imaging shows this change well and cannot name it, which is the honest position on the first scan.

Its best contribution is excluding a fracture, an infarct and a tumour, which is what makes waiting safe. 5.13.7 covers bone tumours.

It is limited because the diagnosis depends on an interval rather than on an appearance, and no sequence shortens that. 5.1.6 covers imaging pitfalls.

No figures appear for accuracy on this page, under decision 028, and no resolution intervals or density values appear either: those are published quantities from particular cohorts and this environment cannot check them.

FRCS Level

How Good It Is

At decision level the imaging buys an interval rather than a diagnosis, and that is a legitimate result. 5.1.3 covers choosing the correct investigation.

The exclusions are what the first scan is for. 5.13.7 covers bone tumours.

Protected weight bearing is reasonable while the interval runs, because the bone is weak in that region. 3.4.9 covers the force transmission.

A fracture appearing during the interval changes the diagnosis and the management together. 5.13.3 covers stress fractures.

Operating on this appearance is the error to avoid. 5.1.2 covers clinical examination versus imaging.

Where It Misleads

The commonest error is naming the condition on the first scan. 5.1.6 covers imaging pitfalls.

It is reported as an osteonecrosis, because both are geographic in a loose sense. 5.13.5 covers osteonecrosis.

It is reported as an infection, because of the effusion and the pain. 5.14.7 covers septic arthritis.

It is reported as arthritis, because the marrow change sits subchondrally in part. 5.20.6 covers reporting osteoarthritis.

It is biopsied, which is the harm this page exists to prevent. 5.13.7 covers bone tumours.

Fellowship Level

Where It Misleads

At fellowship level the patient has usually had two scans in different departments and no interval comparison worth making. 5.18.1 covers the quantitative MRI.

A comparison needs the same scanner and protocol, which referral pathways rarely deliver. 5.5.1 covers the standard protocol.

The condition recurs in other joints, so the history across joints is the most informative single thing available. 4.2.9 covers the onset.

A fracture arising in the region during the interval is the outcome to watch for rather than the one to be surprised by. 5.13.4 covers insufficiency fractures.

Metabolic imaging and quantitative sequences have both been proposed here and neither shortens the interval. 5.18.7 covers the PET-MRI.

The useful report states what was excluded, what the differential remains, the interval proposed, and the protocol the comparison will require. 5.20.1 covers structured reporting.