Early OA

For Medical Students

What It Tests

Early osteoarthritis presents as pain on load in one compartment, stiffness after rest that eases with movement, and an effusion that comes and goes with activity. 4.2.11 covers aggravating factors.

The examination's job at this stage is deciding which compartment is loaded, whether the alignment explains it, and whether the range is still full. 4.5.1 covers the mechanical axis.

It is a difficult examination because the findings are mild and the differential is wide. A meniscal tear, a cartilage lesion and early wear all produce the same compartment pain. 4.17.1 covers the cartilage presentation.

How It Is Performed

Take the history: the pain on load, the stiffness after sitting, the swelling after activity, and how far the patient walks before stopping. 4.2.1 covers pain.

Watch the gait, since an early thrust or a shortened stance phase on one side is visible before anything else. 4.4.1 covers normal gait.

Look at the standing alignment from the front, because the compartment that hurts is usually the compartment the alignment loads. 4.5.2 covers varus alignment.

Assess the effusion, because a recurrent activity related effusion is the sign most often present when the radiograph is still near normal. 4.8.3 covers the bulge sign.

Palpate the joint lines in flexion, since tenderness over the affected compartment is usual and localises the problem. 4.6.4 covers joint line tenderness.

Measure the range both ways, since the first loss in early wear is the last few degrees of flexion rather than extension. 4.7.4 covers the flexion assessment.

Assess the quadriceps, because the bulk and the ability to hold the leg straight reflect how long the knee has been avoided. 4.3.9 covers muscle wasting.

What a Positive Means

Compartment pain with a recurrent effusion, a mildly reduced flexion and an alignment that loads the painful side is the characteristic early picture.

The same findings in a knee with a normal alignment and a mechanical history point to the meniscus instead. 4.9.1 covers the meniscal presentation.

Stiffness that eases within thirty minutes of rising suggests a degenerative rather than an inflammatory process, and the distinction matters. 4.8.9 covers synovitis.

Pain at the front on stairs with no compartment tenderness points to the patellofemoral joint, which is examined differently. 4.18.5 covers that.

A normal examination in a patient with activity related pain is common at this stage and does not rule out early wear.

MRCS Level

How It Is Performed

In a viva this is the knee pain station where the expected answer separates degenerative from mechanical and names the compartment.

The expected points are the history of load related pain and stiffness, the gait, the standing alignment, the effusion, the joint line tenderness, the range, and the quadriceps.

Say that you would assess the alignment standing and not supine, because the load is what matters. 4.3.3 covers standing alignment.

Say that you would examine the hip and the spine, since referred pain explains a proportion of knee pain in this age group. 4.2.15 covers referred pain.

Say that you would ask about night pain and rest pain, which belong to a later stage and change the urgency. 4.18.2 covers established disease.

What a Positive Means

The reasoning expected is that wear begins where the load is highest, so the alignment predicts the compartment and the compartment predicts the findings. 3.5.2 covers contact pressures.

Stiffness after rest reflects the synovial and capsular response rather than cartilage loss, which is why it eases with movement.

The loss of terminal flexion comes from the capsule and the effusion before it comes from the bone, which is why it is recoverable early. 4.7.5 covers the end feel.

Quadriceps wasting is a measure of how long the knee has been protected, not of how worn it is, so it tracks behaviour rather than structure. 4.3.9 covers it.

Both knees are examined and compared, because the contralateral side sets the reference for alignment, range and bulk. 4.1.4 covers the structured approach.

How Good It Is

The examination reliably identifies a symptomatic compartment and an alignment that loads it, and it cannot grade the cartilage loss.

Its best contribution is separating a degenerative pattern from a mechanical one by the history and the stiffness, which the imaging does not do. 4.9.1 covers the mechanical pattern.

It is insensitive to early change, because a knee with cartilage loss can examine normally between episodes.

Weightbearing radiographs show joint space and alignment, so they carry the structural question and the examination carries the symptomatic one. 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 early disease is a treatment category rather than a radiographic one, and the examination establishes whether the symptoms are mechanical, degenerative or both.

A single painful compartment with a correctable alignment and a full range is the group in which load redistribution is considered, so the examination defines it. 4.20.4 covers the osteotomy assessment.

A painful compartment with a fixed deformity or a lost range sits outside that group, and the examination is what finds the difference. 4.5.4 covers the flexion deformity.

A mechanical history on top of degenerative findings raises a degenerate meniscal tear, which is a different conversation and a common one. 4.9.11 covers meniscal examination in the worn knee.

Patellofemoral pain alongside compartment pain changes the options, so both joints are examined rather than one. 4.18.5 covers the patellofemoral examination.

Where It Misleads

The commonest error is accepting the radiograph as the arbiter of early disease when the examination and the symptoms are the thing being treated.

A knee that examines well between episodes misleads if it is examined on a good day, which is why the history carries weight here. 4.2.9 covers the onset.

Referred pain from the hip reproduces the picture closely enough that the hip is examined every time. 4.2.15 covers referred pain.

An effusion attributed to wear can be inflammatory or crystal related, and the pattern of onset is the clue. 4.8.9 covers synovitis.

Quadriceps wasting read as a marker of severity overstates the structural problem, since it reflects disuse. 4.3.9 covers it.

Fellowship Level

Where It Misleads

At fellowship level the risk is treating a compartment when the problem is the whole knee, or treating the whole knee when the problem is one compartment.

The examination distinguishes these by the localisation of the tenderness, the alignment, the range and whether the patellofemoral joint is involved, and each of those can be read too generously. 4.5.1 covers the mechanical axis.

A varus knee with medial pain is the straightforward case. A varus knee with medial pain and lateral joint line tenderness is not, and the second finding is easy to omit. 4.6.4 covers the technique.

Stiffness that is present on rising and lasts beyond an hour belongs to an inflammatory process, and the history question is the only part of the examination that asks it. 4.2.1 covers pain.

An apparently correctable deformity assessed supine can be fixed under load, so the standing and the supine assessments are both done. 4.3.3 covers standing alignment.

The examination cannot say whether the cartilage loss is focal or diffuse, and that distinction drives the treatment more than the symptoms do. 4.17.5 covers articular defects.