Contractures

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Student MRCS FRCS Fellow

For Medical Students

What It Tests

A contracture is a restriction of the passive range caused by shortening of the soft tissues around the joint rather than by anything inside it.

The commonest is a flexion contracture, where the posterior capsule shortens because the knee has been held flexed. 4.5.4 covers flexion deformity.

Assessing it means establishing the passive range, the end feel and the duration, because a contracture that is weeks old behaves differently from one that is months old. 4.7.5 covers the end feel.

How It Is Performed

Measure the passive extension and flexion with the patient relaxed and the limb supported. 4.7.2 covers passive motion.

Note the end feel, since a leathery resistance that gives slightly under sustained pressure is the characteristic finding of a contracture. 4.7.5 covers it.

Distinguish it from a firm abrupt block, which is mechanical, and from a pain limited range, which is irritability. 4.9.8 covers the mechanical cause.

Establish how long the knee has been in its restricted position, from the history and from the records.

Assess the hip, since a hip flexion contracture produces an apparent knee flexion contracture in standing. 4.4.5 covers a related pattern.

What a Positive Means

A leathery end feel with a passive extension deficit indicates a flexion contracture.

A contracture of recent onset in a knee that has been immobilised or effused is usually reversible with movement and time. 4.8.2 covers the effusion.

A contracture of long standing is less reversible, which is why the duration is part of the assessment rather than a historical detail.

A global contracture limiting both extension and flexion indicates arthrofibrosis, which has a less certain outcome than an isolated extension deficit. 4.7.10 covers post-operative range.

A contracture in a knee listed for a ligament reconstruction is a reason to delay the operation rather than a reason to proceed carefully. 4.7.2 covers the range.

Key Learning Points

A contracture is soft tissue shortening rather than anything inside the joint.
The leathery end feel giving under sustained pressure is the characteristic finding.
A recent contracture in an immobilised or effused knee is usually reversible.
A global contracture limiting both directions is arthrofibrosis.
A contracture before a reconstruction is a reason to delay the operation.

MRCS Level

How It Is Performed

In a viva the answer separates the three causes of a restricted passive range, and the end feel is how it does so.

The expected points are the passive measurements, the end feel, the duration, the distinction from a block and from irritability, and the hip.

Say that prevention is the main treatment, because a contracture that has not formed does not need releasing, and early movement is what prevents it.

Say that you would delay a reconstruction in a contracted knee, and say why. 4.7.2 covers the range.

Say that you would assess the quadriceps, since a contracted knee has a wasted quadriceps and the two have to be addressed together. 4.3.9 covers wasting.

What a Positive Means

The reasoning expected is that soft tissue adapts its length to the position it is held in, so a knee held flexed shortens its posterior structures over weeks. 4.7.2 covers passive motion.

That adaptation is viscoelastic at first and becomes structural with time, which is the basis for both the leathery end feel and the value of early movement. 4.7.5 covers the end feel.

An effusion holds the knee flexed, which is why an untreated effusion produces a contracture and why addressing the effusion is part of preventing one. 4.8.2 covers it.

Arthrofibrosis is a more generalised process involving the whole capsule and the fat pad, which is why it limits both directions and why its outcome is less predictable. 4.7.10 covers the post-operative knee.

How Good It Is

The diagnosis of a contracture is clinical and reliable when the passive range and the end feel are both recorded, and unreliable when only the angle is. 4.7.5 covers the end feel.

The distinction from a mechanical block is the part that changes the treatment and the part that depends most on the examiner.

The duration is obtained from the history and the records rather than from the examination, which makes the record part of the diagnosis. 4.1.8 covers it.

Imaging contributes little to a contracture and a great deal to a mechanical block, which is why the clinical distinction has to come first. 4.1.6 covers that relationship.

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

Key Learning Points

Soft tissue adapts its length to the position the joint is held in.
The adaptation is viscoelastic at first and structural with time.
An untreated effusion holds the knee flexed and produces a contracture.
Arthrofibrosis involves the whole capsule, which is why it limits both directions.
The duration comes from the record, which makes the record part of the diagnosis.

FRCS Level

How Good It Is

At decision level a contracture decides timing, feasibility and occasionally the operation itself.

A knee with a flexion contracture cannot be reconstructed to a normal ligament length, so the contracture is treated first and the ligament afterwards. 4.7.2 covers the range.

Early movement after any knee operation is what prevents a contracture, which makes this a page about prevention rather than treatment.

An established contracture after a reconstruction needs the mechanical causes excluded before a release, since releasing an impinging lesion is a different and better operation. 4.7.5 covers the end feel.

A contracture in a knee with a chronically effused joint has a cause that must be addressed, and releasing without addressing it recurs. 4.8.8 covers chronic effusions.

Where It Misleads

The commonest error is recording an angle without an end feel, which leaves a contracture and a block indistinguishable.

The second is treating an effusion related held position as a contracture, which resolves.

The third is releasing a contracture without excluding a mechanical cause.

The fourth is attributing a standing flexion deformity to the knee when the hip is contracted.

The fifth is operating on a ligament in a contracted knee, which produces a stiff and tight result.

Key Learning Points

A knee with a contracture cannot be reconstructed to a normal ligament length.
Early movement after any operation is what prevents a contracture.
An established contracture needs mechanical causes excluded before a release.
A contracture with a chronic effusion recurs unless the effusion is addressed.
An angle without an end feel leaves a contracture and a block indistinguishable.

Fellowship Level

Where It Misleads

In referred practice the contracture is usually established and the question is what can still be achieved.

A patient with an isolated extension contracture and a firm end feel may have a mechanical lesion rather than a contracture, and that is the better diagnosis to find. 4.7.5 covers it.

A patient with a global leathery restriction has arthrofibrosis, and the conversation about a partial improvement rather than a normal knee begins with the examination. 4.7.10 covers the range.

A patient whose contracture has been present for years is unlikely to regain a normal range, and setting that expectation is more useful than attempting a release with an implied promise. 4.7.9 covers functional range.

A patient with a contracture and a chronically deficient posterior cruciate has an abnormal resting position that makes the ligament measurements unreliable, and that limit has to be stated. 4.11.6 covers that knee.

In medicolegal work the absence of any recorded range in the first weeks after an injury or an operation is the commonest reason a stiffness claim cannot be assessed, since the contracture's development cannot be dated. 4.23.7 covers that setting.

Key Learning Points

An isolated extension contracture with a firm end feel may be a mechanical lesion instead.
A global leathery restriction begins the conversation about partial improvement.
A contracture present for years is unlikely to regain a normal range.
A contracture with posterior cruciate deficiency makes the ligament measurements unreliable.
Without early recorded ranges, the contracture's development cannot be dated.

Explore Further

Where this topic came from and where it goes next in the spiral.

References

No reference list is attached to this draft. Evidence verification has not run, because source retrieval was unavailable at generation time. Under the Operations Handbook a missing reference is acceptable and an invented one is a critical failure, so nothing has been cited and no citation marker appears in the text. This page carries no diagnostic accuracy figure, which is decision 023 rather than an omission. The comparative standing of these tests is standard teaching and a specific sensitivity written from memory is the same class of claim as an invented citation, so ACC-001 refuses the number and the page states the comparison. A reviewer with the literature can add the figures into How Good It Is without restructuring the page, and chapter 3.17 lists the studies the figures would come from. Any measurement here, including a flexion angle, is written from standard teaching, has not been checked, and is registered under decision 006 in pipeline/config/figures with a verification state of UNVERIFIED_FROM_MEMORY.

Safety. KneeSchool is educational and does not give individual medical advice. Seek urgent assessment for a knee that cannot bear weight after an injury, a hot swollen knee with a fever, or new numbness, weakness or coldness in the leg or foot.