Valgus Alignment

For Medical Students

What It Tests

A valgus limb has the knee lying lateral to the hip to ankle line, so the lateral compartment carries more load and the medial side is held under tension. 3.13.4 covers the biomechanics.

Assessing it asks the same two questions as varus: how much, and whether it corrects. 4.5.2 covers the mirror case.

The consequence that matters in a ligament assessment is that a valgus limb loads the medial structures continuously, so a medial reconstruction into an uncorrected valgus limb stretches. 4.12.8 covers that assessment.

How It Is Performed

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

Estimate the intermalleolar distance, and record it as an estimate.

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

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

Examine the medial ligaments, since a correctable valgus usually means medial laxity rather than bony change. 4.12.1 covers valgus stress testing.

Look at the feet, because a pronated hindfoot adds valgus at the knee and is sometimes the treatable part. 4.5.1 covers the mechanical axis.

What a Positive Means

A correctable valgus indicates medial ligament laxity, and the medial examination localises it. 4.12.5 covers the corner.

A fixed valgus indicates lateral compartment change or a bony deformity, and the radiograph grades it. 4.1.6 covers that relationship.

A valgus thrust indicates that a medial restraint is absent rather than stretched, which is the significant version of the finding. 4.12.2 covers the test it corresponds to.

A valgus limb with a medial ligament injury is a knee where the laxity will recur after reconstruction unless the alignment is addressed. 4.12.8 covers it.

Valgus in a young patient raises inflammatory arthritis, a growth disturbance or a lateral compartment problem, which is a different differential from the varus knee. 4.2.14 covers inflammatory pain.

MRCS Level

How It Is Performed

In a viva valgus is less commonly asked than varus and the expected answer is symmetrical, with the differential as the addition.

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

Say that you would ask about inflammatory disease, since valgus is the characteristic deformity of rheumatoid arthritis and that changes the whole assessment. 4.2.14 covers inflammatory pain.

Say that you would look at the hindfoot, because a pronated foot contributes and is sometimes the easiest part to treat.

Say that you would obtain long leg standing radiographs for any valgus you intend to act on. 4.5.1 covers the measurement.

What a Positive Means

The reasoning expected is that a lateral shift of the mechanical axis increases lateral compartment load and holds the medial structures in tension. 3.13.4 covers valgus alignment.

A medial structure held under constant tension creeps, which is the mechanism behind the recurrence of medial laxity after reconstruction in an uncorrected valgus limb. 3.9.8 covers medial reconstruction biomechanics.

As the lateral compartment collapses the deformity increases, so valgus with lateral wear progresses by the same feedback as varus with medial wear. 3.13.8 covers alignment and osteoarthritis.

Valgus also affects the patellofemoral joint by increasing the lateral vector on the patella, which is why valgus limbs feature in patellar instability. 2.4.4 covers patellar tracking.

How Good It Is

The clinical assessment is reliable for gross valgus, poor as a measurement, and good at the fixed or correctable question, which is the same profile as varus.

Valgus is harder to assess in an obese patient than varus, because thigh contact prevents the feet being brought together. 4.23.4 covers those patients.

The thrust is again the most specific and consequential finding and requires the patient to walk. 4.4.6 covers the gait.

The differential is where the clinical assessment adds most, since valgus in a young patient points at a systemic cause the examination can pursue. 4.2.14 covers it.

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 valgus alignment decides whether a medial reconstruction has any prospect of holding.

A medial injury in a valgus limb needs the alignment considered before the ligament, and in a chronically valgus knee the correction may replace the reconstruction. 4.12.8 covers that assessment.

A fixed valgus with lateral compartment change is an arthroplasty or osteotomy decision rather than a ligament one, and the examination establishes which category. 4.4.6 covers the gait it presents with.

A valgus thrust in a patient with a reconstructed medial side indicates the reconstruction is failing under load, which is a different finding from a residual grade. 4.12.3 covers the grade.

In an inflammatory valgus knee the soft tissues behave differently and the ligament findings are harder to interpret, which is an argument for making the diagnosis before planning. 4.8.9 covers synovitis.

Where It Misleads

The commonest error is not attempting correction.

The second is treating the estimate as a measurement.

The third is missing an inflammatory cause in a young valgus knee.

The fourth is reconstructing a medial side in an uncorrected valgus limb, which is the sequencing error on this side of the knee.

The fifth is assessing valgus supine, where the deformity disappears.

Fellowship Level

Where It Misleads

In referred practice valgus alignment explains the medial reconstruction that stretched, and the explanation is usually in the limb rather than in the operation.

A patient with a competent medial reconstruction that has become lax over two years in a valgus limb has a creep problem rather than a technical failure. 3.9.8 covers the biomechanics.

A patient with a valgus limb and a stretched cruciate graft has the same mechanism acting on a different structure, and the correction is part of the revision. 4.10.12 covers revision assessment.

In a knee with a previous lateral compartment arthroplasty or osteotomy the alignment has been altered deliberately, and the pre-operative films are needed to interpret the current shape. 4.5.1 covers the measurement.

In the inflammatory knee the valgus progresses with the disease rather than with the mechanics, so a correction in an uncontrolled inflammatory arthritis recurs. 4.8.9 covers synovitis.

In medicolegal work a valgus deformity is almost never attributable to a single injury, which is a useful thing to be able to say clearly. 4.23.7 covers that setting.