Varus Alignment, Alignment Assessment

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Varus Alignment

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For Medical Students

What It Tests

A varus limb has the knee lying medial to the hip to ankle line, so the medial compartment carries more load than it should and the lateral side carries less. 3.13.3 covers the biomechanics.

Assessing it in a knee examination asks two questions: how much varus there is, and whether it is fixed or correctable. 4.3.10 covers deformity.

The second question decides whether the problem is bony or ligamentous, and that is the largest fork in this chapter. 4.5.1 covers the axis.

How It Is Performed

Stand the patient with the feet together and look from the front at eye level, noting whether the ankles touch with the knees apart.

Estimate the intercondylar distance, and record it as an estimate rather than a measurement.

Attempt to correct the deformity by hand with the patient supine, and note whether it corrects.

Watch the patient walk and look for a varus thrust, which is the alignment changing under load. 4.5.7 covers dynamic alignment.

Examine the lateral ligaments, since a correctable varus in an adult usually means lateral laxity rather than bony change. 4.13.1 covers varus stress testing.

What a Positive Means

A correctable varus indicates lateral ligament laxity, and the lateral examination localises it. 4.13.4 covers the corner.

A fixed varus indicates bony or cartilage change in the medial compartment, and the radiograph grades it. 4.1.6 covers that relationship.

A varus thrust indicates that a lateral restraint is absent rather than stretched, and it is the most significant alignment finding in this section. 4.13.8 covers combined injuries.

A varus limb with a medial ligament injury is a knee in which the medial reconstruction has little to hold it in tension, so the laxity may be irrelevant. 4.12.8 covers that assessment.

A symmetrical varus in both limbs is often constitutional, and treating it as acquired is a common error. 3.13.5 covers it.

Key Learning Points

A varus limb loads the medial compartment and unloads the lateral side.
The two questions are how much, and whether it is fixed or correctable.
A correctable varus in an adult usually means lateral laxity.
A varus thrust means a lateral restraint is absent rather than stretched.
A symmetrical varus in both limbs is often constitutional.

MRCS Level

How It Is Performed

In a viva varus alignment is the setup for a question about osteotomy, and getting to the fixed or correctable distinction first is the mark.

The expected points are the standing inspection, the estimate, the attempt at correction, the gait, and the lateral ligament examination.

Say that you would obtain long leg standing radiographs for any varus you intend to act on, and that the examination decides who needs them. 4.5.1 covers the measurement.

Say that you would establish whether the deformity is femoral, tibial or intra-articular, because that decides where a correction would be made.

Say that you would distinguish constitutional from acquired varus by asking about childhood appearance and by looking at the other limb. 3.13.5 covers it.

What a Positive Means

The reasoning expected is that a medial shift of the mechanical axis increases medial compartment load, which accelerates wear there, and reduces the tension in the medial ligaments. 3.13.1 covers the axis.

As the medial compartment collapses the deformity increases, which increases the load again, and that feedback is why varus alignment with medial wear tends to progress. 3.13.8 covers alignment and osteoarthritis.

The lateral structures slacken as the deformity progresses, which is how a varus knee acquires a thrust without a lateral injury. 3.13.7 covers dynamic alignment.

In a cruciate deficient knee the varus limb also alters the loading on the graft, which is part of why alignment belongs in a ligament assessment. 3.10.8 covers reconstruction biomechanics.

How Good It Is

Clinical assessment of varus is reliable for a gross deformity and poor as a measurement, and the fixed or correctable distinction is the part it does well.

It is unreliable in obese patients and in anyone who cannot stand with the feet together, and the radiograph carries the assessment there. 4.23.4 covers those patients.

The thrust is the most specific clinical finding and the most consequential, and it requires the patient to walk. 4.4.6 covers the gait it belongs to.

It cannot localise the deformity, which is the radiograph's job and determines where a correction is made. 4.3.10 covers deformity.

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

Key Learning Points

Medial collapse increases the deformity, which increases the load, so varus with medial wear progresses.
The lateral structures slacken as it progresses, so a varus knee can thrust without a lateral injury.
The varus limb alters the loading on a cruciate graft.
The fixed or correctable distinction is the part the clinical assessment does well.
The thrust is the most specific and consequential finding and requires the patient to walk.

FRCS Level

How Good It Is

At decision level varus alignment decides whether the operation is bony, soft tissue, both, or neither.

A fixed varus with medial compartment change and lateral laxity is an osteotomy problem, and a lateral reconstruction without correction stretches. 4.13.8 covers combined injuries.

A correctable varus with lateral laxity and a normal medial compartment is a ligament problem, and the correction is not needed. 4.13.4 covers the assessment.

A varus limb in a young patient after meniscectomy is a joint preservation problem with a window, and the alignment is the treatable part. 4.9.10 covers meniscal deficiency.

In a chronically cruciate deficient knee a varus limb accelerates the medial compartment change, which is one of the arguments for reconstructing a knee whose complaint is modest. 4.11.6 covers it.

Where It Misleads

The commonest error is not attempting correction, which leaves the central question open.

The second is treating the clinical estimate as the measurement.

The third is reading constitutional varus as pathological.

The fourth is reconstructing a lateral ligament in an uncorrected varus limb, which is the sequencing error this section keeps naming.

The fifth is assessing varus lying down, where the deformity that matters disappears.

Key Learning Points

Varus decides whether the operation is bony, soft tissue, both, or neither.
A fixed varus with medial change and lateral laxity is an osteotomy problem.
A correctable varus with a normal medial compartment is a ligament problem.
A varus limb after meniscectomy in a young patient is a joint preservation problem with a window.
Reconstructing a lateral ligament in an uncorrected varus limb is the sequencing error.

Fellowship Level

Where It Misleads

In referred practice varus alignment is the finding that most often explains a failed lateral reconstruction, and it is usually absent from the first assessment.

A patient with a stretched lateral graft and a varus thrust had the operations in the wrong order, and the revision is a correction rather than another graft. 4.13.4 covers the corner.

A patient with a varus limb and a stretched posterior cruciate graft may have both an alignment and a slope problem, and the slope is the one most often missed. 4.14.5 covers that pattern.

A thrust after an osteotomy means an under correction or a lateral ligament problem the correction exposed, and the pre-operative films separate them. 4.5.1 covers the measurement.

A constitutional varus in an athlete presents a judgement rather than a deformity, since correcting a limb to an axis it has never had has costs that have to be set against the ligament gain. 3.13.5 covers that argument.

In medicolegal work the pre-injury alignment is almost never recorded, so attributing a varus to an injury is usually unsupportable in either direction. 4.23.7 covers that setting.

Key Learning Points

Varus alignment most often explains a failed lateral reconstruction and is usually missing from the first assessment.
A stretched lateral graft with a varus thrust needs a correction, not another graft.
With a stretched posterior cruciate graft the tibial slope is the finding most often missed.
A thrust after an osteotomy is under correction or a ligament problem the correction exposed.
Correcting a constitutional varus in an athlete has costs to set against the ligament gain.

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.