Knee Anatomy & Kinesiology – Gold Rank Review (Sept 26 2023)

Vocabulary flashcards summarizing key anatomical structures, biomechanics, pathologies, and clinical concepts of the knee as presented in the lecture notes.

Knee Joint

Largest and most complex joint of the body, formed by the distal femur, proximal tibia, and patella.

Patella

Largest sesamoid bone; thickest cartilage in the body; increases quadriceps leverage and reduces tendon friction.

Tibial Plateau

Flat tibial condyles; slightly concave surface made more congruent by the menisci.

Medial Femoral Condyle

Longer and larger condyle; anterior prominence prevents lateral patellar dislocation.

Lateral Femoral Condyle

Shorter and smaller femoral condyle.

Modified Hinge Joint

Type of the knee joint—permits flexion/extension and ~40° total axial rotation.

Open-Pack Position (Knee)

25° of knee flexion.

Closed-Pack Position (Knee)

Full extension with tibial lateral rotation.

Capsular Pattern (Knee)

Flexion more limited than extension.

Medial Tibiofemoral Compartment

Major weight-bearing side; common site of OA/DJD and pain from prolonged standing.

Patellofemoral Joint

Plane (gliding) joint; affected in chondromalacia patella, aggravated by prolonged sitting (cinema sign).

Menisci

Semilunar cartilages increasing congruency, absorbing shock, lubricating, and reducing friction; outer third vascular.

Medial Meniscus

C-shaped, attached to ACL and MCL, moves ~6 mm, more often injured.

Lateral Meniscus

O-shaped, attached to PCL and popliteus, moves ~12 mm, less injured.

Coronary (Meniscotibial) Ligaments

Anchor menisci to tibial plateau.

Ligament of Humphrey

Anterior meniscofemoral ligament of the lateral meniscus.

Ligament of Wrisberg

Posterior meniscofemoral ligament of the lateral meniscus.

Medial Collateral Ligament (MCL)

Tibial collateral ligament; resists valgus stress; more frequently injured (e.g., swimmer’s knee).

Lateral Collateral Ligament (LCL)

Fibular collateral ligament; resists varus stress; less commonly injured.

Unhappy Triad (O’Donoghue)

Combined injury of ACL, MCL, and medial meniscus.

Anterior Cruciate Ligament (ACL)

Intracapsular-extrasynovial ligament preventing anterior tibial translation; taut in extension & IR; injured by hyperextension or cutting.

Posterior Cruciate Ligament (PCL)

Strongest knee ligament; prevents posterior tibial translation; injured in dashboard or flexed-knee landing trauma.

Oblique Popliteal Ligament

Extension of semimembranosus tendon reinforcing posteromedial knee.

Arcuate Ligament

Popliteus tendon expansion reinforcing posterolateral knee.

Iliotibial Band (ITB)

Thickened TFL fascia stabilizing anterolateral knee.

Screw-Home Mechanism

Terminal knee rotation (last 20° extension): tibial ER in OKC, femoral IR in CKC, locking the knee.

Unlocking Mechanism

Initiated by popliteus during flexion (tibial IR / femoral ER).

Prepatellar Bursa

Most frequently inflamed knee bursa (housemaid’s knee).

Suprapatellar Bursa

Between quadriceps tendon and femur, superior to patella.

Superficial Infrapatellar Bursa

Anterior to patellar tendon; inflamed in prolonged kneeling (clergyman’s/nun’s knee).

Popliteal (Baker’s) Cyst

Enlarged popliteal bursa, common with knee RA.

Pes Anserinus

Insertion of Sartorius, Gracilis, Semitendinosus on medial tibia; provides medial knee stability.

Biceps Femoris

Lateral hamstring inserting on fibular head; flexes and ERs knee, extends hip.

Semimembranosus

Medial hamstring; contributes to oblique popliteal ligament; flexes and IRs knee.

Semitendinosus

Medial hamstring with prominent distal tendon attaching to pes anserinus.

Sartorius

Longest muscle; ‘tailor’s muscle’; produces hip FAbER and knee flexion + IR.

Gracilis

Bi-articular adductor; assists knee flexion and hip adduction; tightness identified by Phelp’s test.

Popliteus

‘Key to the knee’; unlocks knee via tibial IR, aids flexion.

Gastrocnemius

Two-headed calf muscle crossing knee and ankle; assists knee flexion and plantar-flexes ankle.

Quadriceps Femoris

Primary knee extensor composed of rectus femoris and three vasti; most commonly contused (charley horse).

Rectus Femoris

Only bi-articular quadriceps head; flexes hip and extends knee.

Vastus Lateralis

Largest quadriceps head.

Vastus Medialis Oblique (VMO)

Distal medial vastus fibers; first to atrophy and last to recover after knee surgery.

Vastus Intermedius

Deep quadriceps head; purest and most efficient knee extensor; gives rise to articularis genu.

Articularis Genu

Small muscle fibers retracting knee capsule during extension.

Patella Alta

Abnormally high-riding patella; predisposes to lateral dislocation (camel sign).

Patella Baja

Abnormally low-riding patella.

Q-Angle

Angle between ASIS-patella and patella-tibial tubercle lines; normal 13-18°, >20° linked to PFPS.

Tibiofemoral Shaft Angle

Average 185° (5° valgus); deviations cause genu varum or valgum.

Genu Varum

Bow-leg deformity (<170° medial angle); common in toddlers and knee OA.

Genu Valgum

Knock-knee deformity (<170° lateral angle).

Genu Recurvatum

Hyperextension deformity often seen with quadriceps weakness or spasticity, common in poliomyelitis.

WADS Loading

Patellofemoral compressive forces: Walking 0.3× BW, Ascending stairs 2.5×, Descending 3.5×, Squat 7×.

Odd Facet (Patella)

Patellar facet most commonly affected in chondromalacia; contacts femur >90° flexion.

Contraindicated Exercises in Chondromalacia

Deep knee bends and deep squats increase patellofemoral stress.

Popliteal Fossa

Diamond­-shaped posterior knee space bordered by hamstrings and gastrocnemius; contents (deep → superficial): artery, vein, nerves.

Housemaid’s Knee

Prepatellar bursitis due to frequent kneeling.

Charley Horse

Bruising (contusion) of the quadriceps muscle.

Myositis Ossificans

Heterotopic bone in muscle; quadriceps is the most common lower-extremity site.

Pellegrini-Stieda Disease

Calcification/ossification of the MCL following injury.

Swimmer’s Knee

MCL irritation common in breaststroke swimmers.

Dashboard Injury

Posterior tibial translation trauma causing PCL rupture.

ACL Hyper-extension Injury

Non-contact mechanism where knee extends beyond normal range, tearing ACL.

Tripod Sign

Hamstring-tightness test where patient leans back placing hands behind during passive knee extension.