Question Bank Study Notes Dashboard Flashcards
Start Free Trial
Soft Tissue & Ligamentous Injuries

🦵 Soft Tissue & Ligamentous Injuries

Knee ligaments, meniscal tears, shoulder instability and tendon injuries — the clinical tests are the examiners’ favourite.

Knee Ligament Injuries

The knee is stabilised by four major ligaments working in concert. Understanding the mechanism of injury, the clinical examination test, and the specific direction of instability for each is the core MRCS requirement. The knee also has bony, meniscal, and capsular contributions to stability.

Anatomy First

The cruciate ligaments lie intra-articular but extra-synovial. The ACL runs from the anteromedial tibial plateau to the posterolateral femoral condyle (twisting as it ascends). The PCL is stronger and runs from the posterolateral tibia to the anteromedial femur. Collateral ligaments are extra-articular: MCL is intracapsular in its deep fibres and closely related to the medial meniscus — explaining why they are injured together.

🔵
ACL — Anterior Cruciate
Most commonly injured knee ligament
MechanismNon-contact pivot-shift / deceleration + rotation; valgus force; hyperextension. Classic: football / netball plant-and-twist.
PresentationImmediate haemarthrosis (80% of acute haemarthrosis = ACL), pop heard/felt, inability to continue. Swelling within 2 hours.
Lachman’sKnee at 20–30° flexion. Anterior drawer on tibia — most sensitive test for ACL. Soft end-point = positive.
Anterior DrawKnee at 90°. Less sensitive than Lachman’s (hamstrings splint). Still used in examination.
Pivot ShiftMost specific. Reduction of anterolateral subluxation at 20–30° flexion — clunk felt. Hard to elicit without anaesthesia.
ImagingMRI: T2 signal loss / discontinuity. Segond fracture (lateral tibial plateau avulsion) = pathognomonic of ACL tear.
ManagementAcute: RICE, early physio. Reconstruction (hamstring graft or patellar tendon) for young active patients or functional instability. Non-operative + physio for older/less active.
🔴
PCL — Posterior Cruciate
Strongest ligament in the knee
MechanismDashboard injury: direct force to proximal anterior tibia with knee flexed (RTA). Also hyperflexion, hyperextension.
PresentationLess acute than ACL. Posterior knee pain, swelling. Less dramatic presentation — often missed.
Posterior DrawKnee at 90°. Tibia sags posteriorly (posterior sag sign). Posterior drawer test confirms. Look for ‘step-off’ loss between tibia and femur.
Sag SignLie patient supine, hips + knees at 90° — PCL tear causes tibial sag posteriorly vs normal knee. Best initial screening test.
ManagementOften managed non-operatively with physio (PCL heals better than ACL due to vascularity). Surgery for combined ligament injuries or chronic instability.
🟢
MCL — Medial Collateral
Most common ligament injured overall
MechanismValgus stress (lateral blow to knee). Rugby tackle from outside, football, skiing.
TestValgus stress test at 0° (tests posteromedial capsule too) and 30° (isolates MCL). Medial joint line gapping = positive.
GradingGrade I: sprain, stable. Grade II: partial tear, some laxity. Grade III: complete tear, significant laxity.
AssociationClosely adherent to medial meniscus — combined injury common. Part of Unhappy Triad.
ManagementGrade I–II: conservative (hinged brace, physio). Grade III isolated: usually conservative. Combined injuries: surgical.
🟣
LCL — Lateral Collateral
Least commonly injured; peroneal nerve risk
MechanismVarus stress (medial blow). Less common than MCL as opposite limb protects lateral side.
TestVarus stress test at 0° and 30°. Lateral joint line gapping = positive.
AnatomyUnlike MCL, LCL is not attached to lateral meniscus. Runs from lateral femoral epicondyle to fibular head.
⚠️ At riskCommon peroneal nerve winds around fibular neck — LCL/posterolateral corner injuries may cause foot drop.
ManagementGrade I–II: conservative. Grade III and posterolateral corner injuries: surgical repair/reconstruction.
The Unhappy Triad

O’Donoghue’s Unhappy Triad

ACL + MCL + Medial Meniscus — classically from a valgus-external rotation force (e.g., clipping in American football). The mechanism combines valgus stress (MCL + medial meniscus) with rotational force (ACL). Presents with severe acute haemarthrosis and marked instability. Requires staged surgical management.

Note: Some modern literature suggests the lateral meniscus is more commonly injured with ACL tears (due to the pivot-shift lateral compartment compression), but O’Donoghue’s original description remains the exam classic.

SVG Diagram — Knee Ligament Anatomy

Right Knee — Anterior View (Flexed) with Ligaments FEMUR Med. condyle Lat. condyle TIBIA Tibial plateau ACL PCL MCL LCL Patella Med. men. Lat. men. ACL (Ant. Cruciate) PCL (Post. Cruciate) MCL (Med. Collateral) LCL (Lat. Collateral)
Clinical Examination Tests

Lachman’s Test

Knee 20–30° flexion. Fix femur, draw tibia anteriorly. Soft end-point indicates ACL disruption.

Tests: ACL — most sensitive

Anterior Draw Test

Knee at 90°. Sit on foot. Anterior tibial pull. Less sensitive than Lachman’s due to hamstring splinting.

Tests: ACL

Posterior Draw / Sag

Posterior tibial sag at 90° flexion; posterior drawer confirms. Loss of medial step-off.

Tests: PCL

Valgus Stress Test

Apply valgus force at 0° and 30°. Gapping at 30° = MCL tear. At 0° = MCL + posteromedial capsule.

Tests: MCL

Varus Stress Test

Apply varus force at 0° and 30°. Gapping at 30° = LCL. Check peroneal nerve function.

Tests: LCL

Pivot Shift Test

Valgus + internal rotation while extending from 90°. Clunk at ~20° = anterolateral subluxation reducing.

Tests: ACL — most specific
🧠 Mnemonic — “Anterior Lachman’s, Posterior Dashboard”
ACL → Anterior draw, Lachman’s, Avulsion (Segond fracture), Acute haemarthrosis
PCL → Posterior draw, Posterior sag, Push from Paedal (dashboard injury)
MCL → Medial, Mechanical valgus, Meniscus often co-injured
LCL → Lateral, Looks like varus, Look for peroneal nerve
You're reading the free preview.More detailed sections, comparisons, mnemonics and exam pearls continue below — for subscribers.
`;} document.getElementById('quiz-type-selection').addEventListener('click',e=>{if(e.target.tagName==='BUTTON'){const type=e.target.dataset.quizType;const qs=allQuizData[type]||allQuizData.all;startQuiz(qs);}}); nextBtn.addEventListener('click',handleNext); prevBtn.addEventListener('click',()=>{if(!feedback&&idx>0){idx--;showQ();}}); subBtn.addEventListener('click',()=>{if(!feedback)handleNext();else showResults();});