Observation from the Door

For Medical Students

What It Tests

Observation from the door tests whether the patient's knee limits what they do, which is a different question from how the joint behaves on a couch.

A patient rising from a chair, walking to the couch and getting onto it performs three tasks that load the knee in ways no manual test reproduces. 4.4.1 covers normal gait.

The information is free and it is perishable. Once the patient knows they are being examined they move differently, which is why this part comes first and cannot be done later. 4.1.5 covers the common pitfalls.

How It Is Performed

Watch the patient rise from the chair in the waiting area or the consulting room, and note whether they use their arms and which leg they load.

Watch them walk towards you, noting the stance time on each side and whether the knee reaches full extension.

Watch them turn, because turning loads rotation and most knee complaints are rotational. 4.2.2 covers instability as a symptom.

Watch them get onto the couch, which is a single leg loaded task with a rotational component, and note which leg leads.

Note the walking aid, the footwear, the brace and the strapping, all of which say something the history may not.

What a Positive Means

An asymmetrical rise from a chair indicates that one knee is being avoided, and avoidance is what the patient's complaint consists of.

A shortened stance time on one side is an antalgic pattern and points at pain rather than instability. 4.4.2 covers it.

A knee held in flexion through stance suggests either a flexion deformity or an effusion holding the joint in its most comfortable position. 4.5.4 covers flexion deformity.

A patient who turns in several small steps rather than pivoting is protecting rotation, which is the behaviour a cruciate deficient knee produces. 4.10.3 covers the chronic knee.

A brace or strapping worn to a clinic appointment is a statement about confidence as much as about mechanics, and it is worth asking who advised it. 4.2.32 covers previous physiotherapy.

MRCS Level

How It Is Performed

In a viva the examiner has usually already decided whether you looked, because the instruction to examine the knee is often given while the patient is walking in.

The expected points are the rise, the gait, the turn, the transfer to the couch, and the aids.

Say that you would observe before exposing and before touching, and say why, because the reason is the content of the answer. 4.1.4 covers the structured approach.

Say that you would observe both legs and compare, since every finding in this section is a comparison. 4.1.2 covers the principle.

Say that you would note what the patient does spontaneously, since the instructed version of a movement is a different measurement from the spontaneous one. 4.4.10 covers functional screening.

What a Positive Means

The reasoning expected is that walking and rising are the knee's real loading conditions, so the behaviour under those conditions is the closest thing in the examination to the patient's experience. 3.3.9 covers kinematics during walking.

A knee that avoids terminal extension in stance is avoiding the position in which the quadriceps works hardest, and that avoidance is the common response to pain, to an effusion and to quadriceps weakness alike. 4.7.8 covers extension lag.

Rising from a chair loads the extensor mechanism through a large arc, so an abnormal rise points at the extensor mechanism or the patellofemoral joint rather than at a ligament. 3.3.11 covers kinematics during squatting.

Turning loads internal and external rotation, which is why a protected turn is the inspection equivalent of a rotational test. 3.3.14 covers kinematics during cutting.

How Good It Is

Observation from the door correlates with the patient's complaint better than any single manual test and is almost never recorded, which is an odd combination worth stating plainly.

It is sensitive and not specific. It shows that something is wrong and rarely shows what, which makes it a screen rather than a diagnosis.

It is unreliable in a patient who is anxious, in pain from another joint, or walking on an unfamiliar floor, and all three are common in a clinic.

It is the only part of the examination that cannot be repeated once the patient is undressed and on the couch, which is why its place in the sequence is fixed. 4.3.2 covers gait observation in more detail.

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 this observation sets the question the rest of the examination answers, which is a larger contribution than it is usually given credit for.

A patient whose knee limits a specific task is a patient with a functional problem, and functional problems are what operations are offered for. A grade is not. 4.11.6 covers that argument in its sharpest form.

Where the observation and the couch examination disagree, the observation is more often the one that matches the outcome, and that disagreement is worth writing down rather than resolving in favour of the measurable finding.

The observation also identifies the patient whose complaint is not the knee. A patient who rises badly and walks well is usually describing a hip, and a patient who walks badly and rises well is usually describing the knee. 4.2.15 covers referred pain.

In a revision setting the observation is the most honest assessment available, because every measurable finding has been altered by surgery. 4.10.12 covers revision assessment.

Where It Misleads

The commonest error is not doing it, which is a choice made by starting the examination at the couch.

The second is recording a gait description that was never observed, which appears in letters more often than it should.

The third is over reading a single observation. A patient carrying a bag or wearing unfamiliar shoes walks abnormally for a reason that is not the knee.

The fourth is attributing every abnormality to the knee being examined, when the hip, the ankle and the spine all produce the same patterns. 4.1.4 covers the structured approach.

The fifth is letting the observation replace the examination rather than frame it.

Fellowship Level

Where It Misleads

In referred practice the observation is frequently the only part of the assessment that has not been done, and it is frequently where the referral's answer is.

A patient who walks into the clinic unaided, having been referred with a disabling knee, is describing a mismatch, and establishing whether it is expectation, confidence or compensation is the work of the consultation. 4.22.6 covers the score built for that question.

A patient who is reluctant to be observed, or who performs differently once asked, raises a question the examination cannot settle and that has to be handled rather than recorded as inconsistency. 4.23.7 covers the medicolegal setting.

In the multiply operated knee the observation separates stiffness from instability more reliably than the couch does, because a stiff knee shows itself in the transfer onto the couch and a lax one does not. 4.2.4 covers stiffness.

An athlete walking normally is uninformative, because the task is far below the demand that fails, and the observation has to be moved to a task that approaches it. 4.4.9 covers single leg landing.

The observation is also where a neurological cause declares itself first. A foot that slaps or a toe that catches points at the nerve rather than the joint, and in a knee with lateral ligament surgery that is a specific question. 4.13.4 covers the corner.