Stiffness

For Medical Students

What It Tests

Stiffness in a patient's account can mean a knee that will not bend, a knee that is painful to bend, or a knee that feels tight without any loss of movement.

Only the first is a true loss of range, and only the first will be confirmed on examination. 4.7.7 covers contractures.

Asking about stiffness therefore tests which of the three the patient means, and the answer directs the rest of the assessment.

How It Is Performed

Ask what the knee cannot do rather than whether it is stiff. Can they sit in a car, kneel, get up from a low chair, or straighten the leg fully when standing.

Ask when it is worst. Stiffness after rest that eases with movement is inflammatory or degenerative. Stiffness that worsens through the day is mechanical or related to swelling.

Ask how long it lasts in the morning, since a prolonged morning stiffness points away from a purely mechanical cause. 4.2.14 covers the inflammatory pattern.

Ask whether it came on gradually or after an event, because a sudden loss of extension is a different problem from a gradual one.

What a Positive Means

A sudden inability to fully straighten the knee after an injury is a mechanical block and needs treating as one. 4.2.5 covers locking.

A gradual loss of flexion with pain at the end of range, worse after rest, points to degenerative disease. 4.18.2 covers established disease.

Stiffness after an operation, developing over weeks, points towards arthrofibrosis or towards inadequate rehabilitation, and the two need separating early. 4.7.10 covers post-operative range.

Stiffness with no measurable loss of range is usually describing swelling, pain inhibition or deconditioning rather than the joint.

MRCS Level

What a Positive Means

The reasoning expected here is from the pattern of stiffness to the tissue responsible.

A fixed loss of extension with a hard endpoint suggests bone or a mechanical block. A soft endpoint suggests capsule or muscle. 4.7.5 covers end feel.

A loss of flexion with pain throughout rather than at the end suggests an irritable joint rather than a contracture.

Stiffness that is worse in the morning for under half an hour fits degenerative disease. Stiffness lasting longer and affecting several joints fits an inflammatory arthropathy and needs a different workup.

Stiffness in a child or adolescent with no injury should raise a tumour, an infection or a juvenile arthropathy rather than being managed as mechanical.

How Good It Is

Stiffness as a reported symptom performs poorly on its own and well when paired with its timing.

Paired with the time of day it is one of the more useful discriminators between degenerative and inflammatory disease.

On its own it says little, because the word covers three different problems and patients distribute themselves across all three.

The examination outperforms the history for whether range is actually lost, which is the reverse of the instability case and worth noticing. A patient's estimate of their own range is unreliable in both directions.

FRCS Level

How Good It Is

At decision level stiffness matters most as a predictor and as a contraindication rather than as a diagnosis.

A knee that is stiff before an operation is likely to be stiff after it, and that is among the more reliable predictions available in elective knee surgery.

A pre-operative flexion contracture changes the plan for both osteotomy and arthroplasty, and the history establishes how long it has been there, which the examination cannot.

Stiffness that developed quickly after a previous operation on the same knee raises the risk of it happening again, and that is a history question whose answer rarely appears in a referral letter. 4.2.30 covers previous surgery.

Where It Misleads

The commonest error is accepting stiffness as a diagnosis rather than a symptom, and treating it with a release when the cause is pain or swelling.

The second is attributing a loss of extension to soft tissue when a mechanical block is present. A displaced meniscal fragment produces a loss of extension that no amount of rehabilitation will resolve. 4.9.8 covers mechanical locking.

The third is missing the systemic cause. A patient with stiffness in several joints has been given a mechanical label somewhere upstream often enough to be worth checking deliberately.

And a knee described as stiff by a patient who has become inactive is often describing deconditioning, where the intervention is rehabilitation and the risk is an operation.

Fellowship Level

Where It Misleads

The stiff knee after arthroplasty or reconstruction is a referral where the history determines the plan more than the imaging does.

The key question is when the range was lost. A knee that never achieved range behaves differently from one that achieved it and lost it, and the second raises arthrofibrosis, infection or a mechanical cause.

The second question is what rehabilitation was actually done, as opposed to prescribed. 4.2.34 covers previous rehabilitation, and the answer frequently changes the plan.

The third is whether pain preceded the stiffness or followed it. Pain first suggests a cause that stiffened the knee; stiffness first suggests a capsular process.

A release in a knee whose stiffness is driven by pain of unexplained origin is the intervention most likely to disappoint, and the history is where that risk is identified.

As elsewhere in this chapter, no figure here supports which question discriminates best. The patterns are standard teaching and the numbers were refused under decision 023.