Antalgic Gait

For Medical Students

What It Tests

An antalgic gait is a pattern that shortens the time spent loading a painful limb, and it indicates pain rather than any particular cause of it.

It is the most frequently seen gait abnormality and the least specific, which makes it a finding to recognise and then look past. 4.4.1 covers the normal pattern it modifies.

Its value is that it is objective. A patient who limps is in pain in a way that a pain score does not demonstrate. 4.2.10 covers severity in the history.

How It Is Performed

Watch the patient walk a distance long enough for the pattern to repeat several times.

Compare the time spent on each foot, which is the defining observation: the stance time on the painful side is shorter.

Note the step length, which shortens on both sides because the pattern changes the whole cycle rather than one side of it.

Note whether the trunk moves to reduce the load, which is a compensation rather than part of the pattern, and whether a walking aid is being used. 4.4.5 covers a related trunk pattern.

Ask where it hurts while they walk, because the location during loading is more useful than the location at rest. 4.2.8 covers pain location.

What a Positive Means

A shortened stance time on one side indicates pain on loading that side, and nothing more specific than that.

An antalgic pattern with an effusion suggests the pain is intra-articular, and the effusion is the more useful finding. 4.3.8 covers swelling.

An antalgic pattern with a normal knee examination raises the hip, the spine and the foot, since all three produce it. 4.1.4 covers the structured approach.

An antalgic pattern that is worse on stairs or on slopes points at the patellofemoral joint or at a loaded flexion position. 4.2.11 covers aggravating factors.

An antalgic pattern with a thrust is two findings, and the thrust is the one that changes the plan. 4.5.7 covers dynamic alignment.

MRCS Level

How It Is Performed

In a viva the antalgic gait is often the first thing a candidate names, and the useful answer says so and then moves on to what else is in the gait.

The expected points are the shortened stance time, the shortened step length, the trunk compensation, the aid, and then a deliberate search for a thrust or an avoidance pattern underneath it. 4.4.3 covers the avoidance pattern.

Say that the pattern is not localising and say what you would do next, because that is what distinguishes a description from an assessment.

Say that you would examine the hip in any antalgic gait with an unremarkable knee, since hip pathology referring to the knee is a standard trap. 4.2.15 covers referred pain.

Say that you would ask about night pain and rest pain, because an antalgic gait with those raises a different differential. 4.2.13 covers night pain.

What a Positive Means

The reasoning expected is that loading a joint produces pain proportional to the load and the duration, so reducing stance time reduces both. 3.14.2 covers the stance phase.

The pattern is bilateral in its effect because the gait cycle is a loop, so shortening one stance phase shortens the contralateral step length, which is why the pattern is sometimes described as symmetrically abnormal.

Pain also inhibits the quadriceps, so a long standing antalgic gait is accompanied by quadriceps wasting, and the two findings together indicate duration. 4.3.9 covers wasting.

Where pain and instability coexist, the antalgic pattern usually dominates the gait, which is why an avoidance pattern can be hidden under it and has to be looked for once the pain settles. 4.4.3 covers it.

How Good It Is

The antalgic gait is the most reliably recognised abnormal gait, and recognising it contributes almost nothing to the diagnosis.

It is sensitive for pain on loading and specific for nothing, so its role is confirming that the complaint is real and prompting a search for its source.

It is the gait abnormality most affected by the clinic environment, since a patient walking a short distance on a flat floor in comfortable shoes may not show it at all.

It masks other patterns, which is the practical reason to re-examine the gait once pain has been treated. 4.4.7 covers post-operative gait.

No figures appear for any accuracy comparison on this page, under decision 023, and the comparison is the claim being made.

FRCS Level

How Good It Is

At decision level an antalgic gait establishes that there is something to treat and contributes nothing to what.

Its most useful role is as an outcome measure. A gait that stops being antalgic after a treatment has demonstrated that the treatment addressed the pain, and that is more convincing than a change in a score.

Its second role is as a reason to delay. A knee that is acutely painful enough to produce a marked antalgic gait is a knee whose ligament examination is unreliable, and the plan is made later or under anaesthesia. 4.14.6 covers that setting.

Its third role is to raise the differential. An antalgic gait with rest pain, night pain or a systemic history is not a mechanical presentation and the assessment changes. 4.2.14 covers inflammatory pain.

Beyond those, the finding is a prompt rather than a contribution.

Where It Misleads

The commonest error is stopping at it, which means recording a limp and not looking for the pattern underneath.

The second is attributing it to the knee in front of you.

The third is treating it as a severity measure, which it is only loosely.

The fourth is examining a markedly antalgic knee's ligaments and recording the result as reliable. 4.13.4 covers the assessment that suffers most.

The fifth is using it as an outcome without having recorded it at the start. 4.1.8 covers the record.

Fellowship Level

Where It Misleads

In referred practice a persisting antalgic gait after a technically sound operation is the commonest presentation of a dissatisfied patient, and the gait is the objective part of it.

A patient with a competent reconstruction, a normal laxity examination and a persisting limp has pain rather than instability, and the two need opposite investigations. 4.14.3 covers the pattern that is instability.

An antalgic gait after an arthroplasty or a reconstruction raises low grade infection, and in a knee with no other explanation it is worth excluding. 4.3.6 covers the skin.

A patient whose antalgic gait is intermittent and whose examination is normal is worth observing on more than one occasion, because a single clinic observation is a small sample of a variable problem.

In the chronically deficient knee the appearance of an antalgic pattern where there was previously an avoidance pattern indicates compartment change rather than ligament failure, and it is the gait that sees it first. 4.11.6 covers that progression.

In medicolegal work the presence or absence of an antalgic gait is one of the most frequently disputed observations, and recording the distance walked and the conditions makes the observation defensible. 4.23.7 covers that setting.