Surgical Scars

For Medical Students

What It Tests

Scars record what has been done to a knee, and in a patient whose history is incomplete they are often the more reliable account. 4.2.30 covers previous surgery as a history item.

They also constrain what can be done next. The soft tissue envelope has a blood supply, and an incision crossing an old one can leave skin between them without enough, so the existing scars decide the available approaches.

Reading them is a matter of pattern recognition: where the scar is, how long it is, which direction it runs, and how well it has healed.

How It Is Performed

Expose both knees fully and look at the front, the sides and the back of each.

Note each scar's position, length, orientation and quality, and whether it is mature, widened, tethered or keloid.

Note arthroscopy portal scars, which are small and in predictable positions at the front of the joint, and count them.

Note the position of any graft harvest scar, since it says which graft was used and therefore something about the operation. 4.10.11 covers post-reconstruction assessment.

Ask the patient what each scar was for, and record which ones they can account for and which they cannot.

Look at the back of the knee and at the thigh and calf, because posterior and proximal scars are the ones that get missed.

What a Positive Means

Two anterior portal scars with a vertical scar over the patellar tendon or the hamstring origin indicates a cruciate reconstruction, and which one indicates the graft.

A long medial parapatellar scar suggests an arthroplasty or an open procedure rather than an arthroscopic one.

A lateral scar running towards the fibular head suggests lateral ligament or corner surgery, and it raises the question of the common peroneal nerve. 4.13.4 covers the corner.

A widened, tethered or adherent scar indicates a healing problem, which changes the risk of any further surgery through it.

A scar the patient cannot account for is a gap in the history that has to be filled from the records rather than guessed at.

MRCS Level

How It Is Performed

In a viva scars are an invitation to reconstruct the history, and a candidate who names the likely operations from the pattern is answering the real question.

The expected points are full exposure including the back of the knee, the position, length, orientation and quality of each scar, the portals, the graft harvest site, and asking the patient.

Say that you would look at the whole limb, since a hamstring harvest scar sits distal to the knee and a quadriceps harvest scar proximal to it.

Say that you would ask for the operation notes rather than relying on the pattern, because the pattern narrows the possibilities and does not settle them.

Say that you would assess the skin's mobility over the joint, since a tethered scar can restrict movement mechanically. 4.7.7 covers contractures.

Say that you would record the scars in a diagram or in words precise enough to be matched at the next visit. 4.1.8 covers the record.

What a Positive Means

The reasoning expected is that the skin around the knee is supplied by a network whose branches run in predictable directions, so an incision's orientation determines what it divides.

Two incisions close together leave the skin bridge between them dependent on a reduced supply, which is the reason a planned approach may be dictated by an old one rather than by the pathology.

A tethered scar limits skin excursion, and skin excursion is required for flexion, so a scar can mechanically restrict movement independently of the joint. 4.7.4 covers flexion assessment.

Previous surgery also alters the structures the examination reads. Scar can substitute for ligament and give a firm endpoint over a lax joint, which is a finding this section has described on several pages. 4.12.3 covers one of them.

How Good It Is

Reading scars is reliable for establishing that surgery happened and unreliable for establishing what was done, and that distinction is worth keeping.

An arthroscopic portal pattern is recognisable. The operation performed through it is not, and a diagnostic arthroscopy and a meniscectomy leave the same scars. 4.9.10 covers the consequence of the second.

A graft harvest scar narrows the possibilities usefully, which makes it the most informative single scar in a knee with ligament surgery.

Where the scars and the patient's account disagree, the operation notes settle it, and the examination's job is to notice the disagreement. 4.2.30 covers the history.

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 the scars decide feasibility, and feasibility is a harder constraint than indication.

A knee with multiple incisions, thin or adherent skin, and a history of wound problems may not tolerate the operation its ligament findings indicate, and the scars are where that is established.

The orientation of existing scars dictates the approach for any revision, and in a knee with several, the plan may be built around the skin rather than around the pathology.

A graft harvest scar also tells you what is no longer available, which constrains a revision reconstruction directly. 4.10.12 covers revision assessment.

A lateral scar in a knee with an abnormal gait raises a previous nerve injury, and establishing that before offering surgery is part of the consent rather than a discovery afterwards. 4.13.4 covers the corner.

Where It Misleads

The commonest error is not looking at the back of the knee.

The second is assuming an operation from a scar, which narrows the field and does not identify the procedure.

The third is not obtaining the operation notes, which is the only reliable account.

The fourth is examining a knee with surgical scars against the expectations for a native knee, where the endpoints and the tracks have been altered. 4.12.8 covers that assessment.

The fifth is recording scars present without describing them, which makes the record useless for the next comparison.

Fellowship Level

Where It Misleads

In revision practice the scars are frequently the finding that changes the answer, and they are the finding most often recorded as present and not described.

A knee with three or more incisions and an adherent anterior scar has a realistic risk of a wound problem that outweighs the gain from a further ligament reconstruction, and that calculation belongs in the consultation rather than in the operating theatre.

A patient with a previous infection and a sinus or a puckered scar has a possibility that has to be excluded before any revision, and the examination is where it is raised. 4.3.6 covers the skin.

Scars from an osteotomy change the alignment history, so a knee with a lateral tibial scar and a varus limb has had a correction that did not hold or was incomplete, and the pre-operative films are needed to interpret it. 4.5.1 covers the mechanical axis.

A graft harvest scar on the contralateral limb is easy to miss and changes the reconstruction options, which is a reason to expose both legs in a revision assessment.

In medicolegal work the scars are the least disputable evidence about what was done, and a careful description of them at first presentation is worth more than a summary of the history. 4.23.7 covers that setting.