Previous Injections

For Medical Students

What It Tests

Asking about injections tests three things: what has been tried, what the response was, and whether there is any possibility of infection.

The response to an injection is a diagnostic result the patient has already produced, which makes this question more useful than it looks.

The infection question is the time-critical one, and it is why this history is taken before any further intervention.

How It Is Performed

Ask what was injected: a steroid, a local anaesthetic, hyaluronic acid, platelet rich plasma, or something they cannot name.

Ask where: into the joint, around a tendon, or into a bursa, since these are different tests with different meanings.

Ask how many, over what period, and when the most recent one was.

Ask what happened: immediate relief, delayed relief, no relief, or worse.

Ask specifically whether the knee became hot, swollen or more painful in the days afterwards, and whether they needed antibiotics or admission.

What a Positive Means

Good temporary relief from an intra-articular injection confirms the symptom is coming from inside the joint, which is useful when that was in doubt.

No relief at all from a well placed intra-articular injection suggests the pain is not intra-articular, and that is a strong and under-used piece of information. 4.2.15 covers referred pain.

Relief from an injection around a tendon or bursa localises the problem outside the joint. 4.16.7 covers pes anserinus pathology.

A knee that became hot and swollen after an injection is a septic arthritis question until proven otherwise, however long ago it was.

Repeated steroid injections into the same joint are relevant to any planned surgery and the number and timing matter.

MRCS Level

What a Positive Means

The expected reasoning treats an injection as a diagnostic block as well as a treatment.

A local anaesthetic response is immediate and short, and it localises. A steroid response is delayed and longer, and it tells you about inflammation.

Separating the two in the history matters, because a patient who had immediate relief for an hour and nothing after has had a positive diagnostic block and a negative therapeutic result.

An injection into a joint that gave no relief at all should prompt review of whether the injection reached the joint, since a blind injection does not always.

Recent intra-articular steroid is a recognised consideration before arthroplasty, and the interval is the relevant historical detail.

How Good It Is

The injection history performs well for localisation and modestly for prognosis.

It performs particularly well in the knee with several possible pain sources, where a response separates intra-articular from extra-articular better than imaging does.

It performs poorly when the patient cannot say what was injected or where, which is common, and the records are then needed.

The safety question performs well regardless, because a patient remembers a knee that became hot and needed antibiotics.

FRCS Level

How Good It Is

At decision level the injection history carries two decisions.

The first is diagnostic: a patient whose pain responds to an intra-articular injection has demonstrated that the joint is the source, which supports an intra-articular intervention.

The second is about timing and risk: recent intra-articular steroid before an arthroplasty is associated with concern about infection and the interval is a real planning factor.

A patient who has had many injections with diminishing effect has usually exhausted that route, and saying so is more useful than offering another.

A patient whose pain has never responded to any injection, with modest imaging findings, should prompt a broader assessment rather than a mechanical operation. 4.2.12 covers relieving factors.

Where It Misleads

The commonest error is not asking, which loses a free diagnostic test.

The second is accepting the patient's account of what was injected, since steroid, hyaluronic acid and platelet preparations are frequently confused.

The third is dismissing a post-injection infective episode because it was years ago and settled, when it bears on every subsequent implant decision.

And over-reading a positive response. An intra-articular injection relieving pain confirms the joint and does not identify which structure in it.

Fellowship Level

Where It Misleads

In referred practice the injection history is most often the thing that has not been taken.

A patient referred for consideration of arthroplasty needs the date of the last intra-articular steroid established, and it is frequently absent from the letter.

A patient with a painful arthroplasty or a painful reconstruction who has had injections into it needs an infection history taken carefully, because a low grade infection following an injection can present late and quietly. 4.20.8 covers the assessment.

A diagnostic injection is also a tool rather than only a history item: in a knee with both a degenerate hip and a degenerate knee, or both a patellofemoral and a tibiofemoral problem, an injection answers a question the examination cannot.

Using it that way is a legitimate step and is often quicker than further imaging.

No figure here supports these claims, under decision 023.