Arthritic Gait

For Medical Students

What It Tests

An arthritic gait combines a shortened stance time on the affected side with a reduced range of knee movement through the cycle and, where the compartment has collapsed, a thrust. 3.14.11 covers the biomechanics.

It belongs in a ligament heavy section because a chronically unstable knee ends up here, and the appearance of this pattern in a patient whose ligament findings are unchanged is the important finding. 4.11.6 covers the knee it happens to.

The pattern is a combination rather than a single observation, which is why it is recognisable as a whole and hard to define by any one feature. 4.4.2 covers one of its components.

How It Is Performed

Watch the patient walk from the front, the side and behind, over a repeating distance.

Note the stance time, which is shortened on the affected side.

Note the range of knee movement through the cycle, which is reduced, so the knee moves as a stiffer segment than normal. 4.7.9 covers functional range.

Note any thrust as weight is taken, since a varus thrust indicates medial compartment collapse and a valgus thrust the lateral. 4.5.7 covers dynamic alignment.

Note the standing alignment before and after the walk, since a thrust often accompanies a fixed deformity. 4.3.3 covers standing alignment.

What a Positive Means

A shortened stance time with a reduced knee excursion indicates a painful, stiff knee, and the joint surface is the usual cause in an older patient.

A varus thrust in this pattern indicates medial compartment collapse, and it changes the treatment from a ligament problem to an alignment one. 4.5.2 covers varus alignment.

A fixed flexion deformity with this pattern indicates established change rather than a recent problem. 4.5.4 covers it.

The appearance of this pattern in a patient with a known ligament deficiency and unchanged ligament findings indicates compartment change, and the gait usually shows it before anything else does. 4.11.6 covers that progression.

The same pattern in a younger patient after a meniscectomy raises early compartment change, which is a recognised consequence. 4.9.10 covers meniscal deficiency.

MRCS Level

How It Is Performed

In a viva this pattern is usually a prompt to talk about alignment, and going there without being pushed is the mark.

The expected points are the three views, the stance time, the reduced knee excursion, the thrust, and the standing alignment.

Say that you would obtain long leg standing radiographs for any thrust, since the alignment is a measurement rather than an impression. 4.5.1 covers it.

Say that you would distinguish a thrust from a fixed deformity, because the first is dynamic laxity and the second is structural. 4.3.10 covers deformity.

Say that you would examine the hip, because hip osteoarthritis produces a very similar pattern and refers to the knee. 4.4.5 covers that pattern.

What a Positive Means

The reasoning expected is that a painful joint surface limits both the load and the arc over which it is carried, so the gait shortens the stance and reduces the excursion together. 3.14.11 covers the gait.

Compartment collapse changes the limb's alignment, and when the collateral structures on the collapsed side slacken the knee thrusts under load, which is a dynamic finding on a structural problem. 3.13.8 covers alignment and osteoarthritis.

A thrust therefore means the deformity has progressed beyond cartilage loss alone, and that is why it is the finding that most changes the treatment. 3.13.3 covers varus alignment.

In the chronically ligament deficient knee the progression is the other way round: the laxity came first and the compartment change followed, and the gait records the transition. 4.11.6 covers it.

How Good It Is

The arthritic gait is recognisable as a pattern and non specific in each of its parts, so it is a gestalt finding rather than a test.

Its most useful single component is the thrust, which is specific for a structural alignment problem and visible to anyone who looks from the front.

It is unreliable in distinguishing hip from knee, which is the commonest differential it faces, and the hip examination settles that. 4.4.5 covers it.

Radiographs grade what the gait suggests, and in this pattern the imaging is clearly the measurement. 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.

FRCS Level

How Good It Is

At decision level this gait moves a patient from a ligament pathway to an alignment or arthroplasty pathway, which is the largest change of direction in this chapter.

A varus thrust with medial compartment change in a ligament deficient knee makes the operation an osteotomy rather than a reconstruction, or neither. 4.13.8 covers combined injuries.

A patient whose gait has moved from an avoidance pattern to this one has progressed, and the plan changes category rather than degree. 4.4.3 covers the earlier pattern.

In a younger patient this pattern is the argument for joint preserving surgery rather than ligament surgery, and the gait is often the first sign that the window is closing.

Following the gait is more informative than following the laxity in these knees, because the laxity is stable and the joint is not. 4.11.2 covers the grade.

Where It Misleads

The commonest error is attributing the pattern to the ligament findings that are already documented, when the gait has changed and the ligaments have not.

The second is not distinguishing a thrust from a fixed deformity.

The third is attributing the pattern to the knee when the hip is responsible.

The fourth is recording the pattern without the standing alignment, which is the measurement the plan needs.

The fifth is reading the pattern as inevitable progression in a young patient, where a correction may change its course.

Fellowship Level

Where It Misleads

In referred practice this gait is often the finding that reframes a referral from a ligament question into a joint preservation one.

A patient referred for revision cruciate reconstruction who walks with a varus thrust and a reduced excursion is a patient whose compartment, not whose graft, is the problem, and that conversation is the consultation. 4.10.12 covers revision assessment.

A patient with a previous meniscectomy, a stable knee and this gait in their thirties has a joint preservation problem with a narrow window, and the gait is frequently the earliest sign. 4.9.10 covers meniscal deficiency.

A thrust after an osteotomy means an under correction or a ligament problem the correction exposed, and the pre-operative films are needed to tell which. 4.5.1 covers the measurement.

In the posterior cruciate deficient knee the medial compartment changes in a particular pattern, and a gait that has deteriorated with an unchanged drawer is that change rather than a ligament failure. 4.11.6 covers it.

In medicolegal work the development of this gait after an injury is the strongest observational evidence of progression, and its documentation over time is usually incomplete. 4.23.7 covers that setting.