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Knee for FRCS (Tr & Orth)

The knee splits into two halves. Arthroplasty and osteotomy cover alignment and the mechanical axis, bone cuts and gap balancing, constraint, unicompartmental replacement, realignment osteotomy and the complications of knee replacement — instability, stiffness, patellar maltracking, infection and revision. Soft-tissue knee covers the cruciate and collateral ligaments and the posterolateral corner, the menisci and articular cartilage, and the patellofemoral joint and extensor mechanism. The applied anatomy and biomechanics of the knee underlie both halves and are tested directly.

125 questions in the bank · 2 topics Updated 11 November 2026
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Topics in this domain

  • Knee arthroplasty & osteotomy50
  • Soft-tissue knee & sports injuries75

What the paper tends to test

  • Gap-balancing questions describe a trial reduction that is tight or loose in flexion, extension or both, and ask for the correct adjustment.
  • Component rotation is tested through its consequence: internal rotation of the femoral or tibial component causes patellar maltracking.
  • Ligament questions ask for the examination finding that isolates a structure — the Lachman test for the anterior cruciate ligament, the dial test for the posterolateral corner, the posterior drawer for the posterior cruciate ligament.
  • Meniscal questions turn on blood supply and tear pattern: which tears can heal after repair, and why a root tear matters.
  • Patellofemoral instability questions test the medial patellofemoral ligament, trochlear dysplasia, patella alta and the tibial tubercle–trochlear groove distance.
  • Osteotomy questions ask who is suitable: the younger, active patient with unicompartmental disease and malalignment, and no inflammatory arthritis.

Classic traps and discriminators

  • A knee that is tight in both flexion and extension needs more tibia resected, because the tibial cut affects both gaps; a knee tight only in extension needs the extension gap addressed — posterior capsular release or more distal femoral resection.
  • Increased external rotation on the dial test at 30° only suggests an isolated posterolateral corner injury; increased at both 30° and 90° suggests a combined posterior cruciate and posterolateral corner injury.
  • A Segond fracture — a small avulsion from the lateral tibial plateau — looks trivial but is strongly associated with rupture of the anterior cruciate ligament.
  • Only the peripheral part of the meniscus is vascular, so peripheral longitudinal tears are the ones that heal after repair. A posterior root tear abolishes hoop stresses and behaves biomechanically like a total meniscectomy.
  • The common peroneal nerve is at risk when a fixed valgus and flexion deformity is corrected at knee replacement; a new foot drop is managed first by releasing the dressings and flexing the knee.

Free knee practice questions

From the free sample — original, referenced, with the full explanation. Rate your confidence first.

13Knee·Knee arthroplasty & osteotomy
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An elective orthopaedic unit is rewriting its protocol for primary total knee replacement, and its surgeons disagree about the patella.

According to NICE guidance on primary joint replacement, how should the patella be managed in a primary elective total knee replacement?

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14Knee·Soft-tissue knee & sports injuries
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A 26-year-old netball player with an anterior cruciate ligament-deficient knee is examined under anaesthesia. With valgus and internal rotation applied, the lateral tibial plateau lies subluxed anteriorly in extension and reduces with a clunk at about 30° of flexion.

Which structure produces the reduction?

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Free revision notes

The stress–strain curve and the material properties of orthopaedic biomaterials

The stress–strain curve for FRCS (Tr & Orth): Young’s modulus, yield, ultimate strength, toughness, fatigue and viscoelasticity, applied to metals, polyethylene, cement and ceramics.

Read · 10 min

Knee questions, answered

How do you balance the flexion and extension gaps in a total knee replacement?

Work out which gap is wrong. The tibial cut affects both gaps, so a knee tight in flexion and extension needs more tibia, and one loose in both needs a thicker insert. The distal femoral cut affects only the extension gap; the posterior femoral cut and femoral component size affect only the flexion gap. Adjust the cut or the size that changes the gap at fault without disturbing the other.

Which meniscal tears can be repaired?

Tears most likely to heal are longitudinal tears in the vascular peripheral zone of the meniscus in a stable or stabilised knee, particularly in younger patients and when repaired at the time of cruciate ligament reconstruction. Root tears are repaired where the cartilage is preserved because of their biomechanical consequences.

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