Night Pain

For Medical Students

What It Tests

Asking about night pain tests whether the pain is load-dependent, because at night there is no load.

A knee that hurts when nothing is loading it has either become severely degenerate, become inflamed, or has a cause that is not mechanical at all.

This is the screening question of the knee history, and it is asked on every patient regardless of the presenting complaint.

How It Is Performed

Ask whether the pain wakes them, which is different from asking whether it hurts at night.

Many patients have pain on turning over or when the knee is knocked, and that is positional rather than true night pain.

Ask whether they wake because of the pain, how often, and whether they can get back to sleep.

Ask about associated features: fever, sweats, weight loss, pain elsewhere, and whether they feel generally unwell.

Ask about recent injections, operations or illness, because infection is the time-critical cause. 4.2.31 covers previous injections.

What a Positive Means

Night pain in a severely degenerate knee is common and is a marker of advanced disease rather than of something else. 4.18.2 covers established disease.

Night pain with warmth, swelling and systemic features is an inflammatory or infective picture and takes priority over everything in this chapter. 4.8.10 covers crystal arthropathy.

Night pain with no mechanical pattern, in a knee with modest findings, raises a cause outside the joint, including the hip and the spine. 4.2.15 covers referred pain.

Unremitting night pain in a child or young adult, particularly with a mass or with systemic features, must have a tumour excluded before anything else.

MRCS Level

What a Positive Means

The expected reasoning is that night pain moves the patient out of the mechanical pathway until a mechanical explanation is established.

Rest pain and night pain together in an older patient with advanced radiographic change supports arthroplasty rather than a lesser procedure. 4.18.7 covers the assessment.

Night pain in an acutely swollen knee after any intervention is a surgical emergency until infection is excluded, and the history is where the suspicion arises.

Night pain with stiffness lasting more than an hour in the morning, in more than one joint, fits an inflammatory arthropathy. 4.2.14 covers the pattern.

Night pain relieved by walking about is more typical of claudication or a spinal cause than of a knee.

How Good It Is

Night pain is not specific but it is one of the most useful questions in the chapter because of what a positive answer obliges you to do.

Its value is as a trigger rather than a discriminator: it changes the differential that is being worked rather than identifying the cause.

A negative answer is reassuring about the categories it screens for and says nothing about the mechanical diagnosis.

It is the question most often omitted from a focused knee history and the one whose omission has the highest cost, which is why it has its own page.

FRCS Level

How Good It Is

At decision level night pain is both a severity marker and a safety question, and the two roles should be kept separate.

As a severity marker in degenerative disease it is among the features that most strongly supports intervention, because it indicates the symptom is no longer activity-limited.

As a safety question it is the main screen for infection, inflammation and malignancy in a clinic that is otherwise thinking mechanically.

A patient with night pain and a modest mechanical picture should not have a mechanical operation until the other categories are excluded, and that sequence is the whole point of the question.

Where It Misleads

The commonest error is accepting positional discomfort as night pain, which over-calls it, and the remedy is the waking question.

The second is dismissing it in a patient with obvious degenerative change, where it is expected, and therefore missing a superimposed infection or a second pathology.

The third is attributing night pain after an arthroplasty to normal recovery beyond the period where that is plausible. 4.20.8 covers the assessment.

And night pain in a patient on anticoagulants or immunosuppression, or with diabetes, shifts the threshold for investigating infection substantially.

Fellowship Level

Where It Misleads

In referred practice night pain after surgery is the presentation where the history most often has to override an established mechanical narrative.

A knee that has hurt at night since an operation, with or without swelling, needs infection excluded however long ago the operation was and however normal the inflammatory markers have been in the past.

A low grade chronic infection can present with pain, stiffness and night pain and little else, and the history of the early post-operative period is often where the clue is.

Night pain after a reconstruction in a young patient, with no swelling and a stable knee, more often reflects a pain process than a structural one, and further surgery is the intervention least likely to help.

The judgement that is hardest is when to stop investigating a patient with night pain and no cause found, and the history cannot settle that.

No figure here supports any of these claims, under decision 023.