Osteotomy

For Medical Students

What It Shows

Post-operative imaging of an osteotomy shows the correction achieved, the union of the cut and the fixation. 5.16.5 covers osteotomy planning.

The correction is measured on a standing long leg radiograph, as the plan was. 5.3.6 covers the long leg alignment films.

It matters because the achieved correction decides whether the operation did what it was for. 5.3.7 covers the mechanical axis.

How It Is Acquired

Obtain a standing long leg film including the hip and the ankle. 5.3.6 covers the long leg alignment films.

Measure the alignment by the same method used in the plan. 5.3.7 covers the mechanical axis.

Assess union at the osteotomy, with any gap or graft. 5.5.6 covers the bones.

Assess the fixation for migration or breakage. 5.3.2 covers the lateral view.

Assess the joint line and the patellar height, both of which a tibial correction changes. 5.3.9 covers the joint line obliquity.

What Normal Looks Like

Alignment at the planned target, measured by the planning method. 5.3.7 covers the mechanical axis.

Progressive union across the osteotomy. 5.5.6 covers the bones.

Fixation in position and intact. 5.3.2 covers the lateral view.

A joint line and patellar height consistent with the correction performed. 5.12.2 covers patella alta.

What Abnormal Looks Like

Alignment short of or beyond the planned target. 5.3.7 covers the mechanical axis.

Delayed union or a persisting gap at the cut. 5.5.6 covers the bones.

Loss of correction across serial films. 5.3.6 covers the long leg alignment films.

Broken or migrated fixation. 5.3.2 covers the lateral view.

An intra-articular fracture through the hinge. 5.16.1 covers the fracture assessment.

MRCS Level

How It Is Acquired

In a viva the expected answer re-measures rather than describes.

The expected points are the standing long leg film, the planning method, the union, the fixation, and the joint line.

Say that a supine film cannot assess the correction. 5.3.6 covers the long leg alignment films.

Say that the achieved correction is not assumed from the operation note. 5.20.8 covers common reporting errors.

Say that the examination carries the function. 4.20.4 covers the osteotomy examination.

What Abnormal Looks Like

The reasoning expected is that the operation's purpose was to move load, so the only finding that reports success is the loaded alignment, which requires the patient to stand. 5.3.7 covers the mechanical axis.

Union and correction are independent: a united osteotomy can sit in the wrong place, and a correct one can fail to unite. 5.5.6 covers the bones.

A correction alters every other measurement made on that limb, so the pre-operative set is the only comparable one. 5.16.3 covers the rotational profiles.

The receiving compartment now carries the load and becomes the compartment to watch. 5.3.17 covers joint space narrowing.

How Good It Is

Radiography is the best available assessment of an osteotomy and depends entirely on being acquired the same way each time.

Its best contribution is the loaded alignment, the union and the fixation. 5.3.6 covers the long leg alignment films.

It is limited by positioning, by rotation changing the apparent correction, and by saying nothing about whether the soft tissues tolerate it. 5.1.6 covers imaging pitfalls.

No figures appear for accuracy on this page, under decision 028, and no correction values, axis angles or union intervals appear either: those are published quantities tied to particular techniques and this environment cannot check them.

FRCS Level

How Good It Is

At decision level the imaging decides whether the correction needs revising and whether the fixation can come out. 5.16.5 covers osteotomy planning.

Under-correction with persisting symptoms is a different problem from a non-union. 5.5.6 covers the bones.

The receiving compartment's state decides whether further correction helps. 5.3.17 covers joint space narrowing.

Patellar height and the joint line change the patellofemoral joint and belong in the assessment. 5.12.7 covers the patellofemoral arthritis.

A later arthroplasty is planned from these films, so the record matters beyond this operation. 5.16.6 covers arthroplasty planning.

Where It Misleads

The commonest error is measuring the correction on a film that does not include both joints. 5.3.6 covers the long leg alignment films.

Limb rotation on the film changes the apparent correction. 5.1.6 covers imaging pitfalls.

Hardware prominence is reported as failure. 5.3.2 covers the lateral view.

A persisting lucency at the cut is read as non-union when a graft is incorporating. 5.5.6 covers the bones.

The patellofemoral consequence is omitted. 5.3.3 covers the skyline view.

Fellowship Level

Where It Misleads

At fellowship level the limb has been corrected and the symptoms have not resolved. 5.16.5 covers osteotomy planning.

Whether the correction was wrong, lost or insufficient needs the plan, the immediate film and the current film together, and the first two are often missing. 5.20.1 covers structured reporting.

A corrected limb is a changed limb, so every later measurement, the arthroplasty references included, describes the operation. 5.16.6 covers arthroplasty planning.

Serial films from different departments in different positions compare radiography as much as alignment. 5.3.6 covers the long leg alignment films.

Converting a corrected knee to a replacement is harder, and the imaging should say what the surgeon will meet. 5.17.8 covers the total knee replacement.

The useful report gives the measured alignment with its method, the union, the fixation, the joint line, the patellar height and the receiving compartment. 5.20.1 covers structured reporting.