Lower limb anatomy (knee and hip)

Question 1

Musculature/connective tissues

Answer 1

Strength, stability, and movement

Flexion/extension

Abduction/adduction

Rotation

Divided into compartments in leg (ANTERIOR/LATERAL/POSTERIOR) separated by bones and fibrous tissue (fascia)

Question 2

Nervous supply

Answer 2

Motor and sensory nerves arise from the lumbar and sacral regions; L1-S3

Innervate the lower limbs in specific regions (dermatomes/myotomes)

Important in clinical assessment and for consideration in trauma

Question 3

THE KNEE

Answer 3

Largest joint in the body

Bony anatomy relies a lot on soft tissues for strength/stability

Prone to trauma due to extrinsic position

Injuries Common in teenage/adult life in sports/RTC’s

Arthritis / degenerative conditions common

Question 4

Knee joint

Answer 4

Synovial bicondylar joint

Wide range of flexion/extension

Weight-bearing joint

Most force through medial joint

Can be altered by altered gait/pathology:
Genu varus
Genu valgus

Question 5

the knee on standing

Answer 5

Designed to ‘lock’ on extension

Improves efficiency by reducing muscle fatigue

Enabled by:
Flattened articular surfaces of distal femur
C.o.g anterior to knee, pushes it back
Femur is rotated medially which tightens ligaments

Flexion is initiated by popliteus muscle which laterally rotates femur and releases locking

Question 6

The knee: bones and synovial joints

Answer 6

4 bones:
Femur
Tibia
Fibula
Patella

Synovial joint, 2 articulations (3 compartments):
Femoro-tibial (medial / lateral)
Patello-femoral

Proximal tibio-fibular joint

Question 7

Distal femur

Answer 7

Formed predominantly by two rounded condyles

Two smaller epicondyles provide attachment for collateral ligaments

Condyles separated posteriorly by intercondylar fossa; attachment for cruciate ligaments

Anteriorly they form a v-shape for articulation with the patella

covered by hyaline cartilage

Condyles flattened on distal end
More rounded posteriorly

More stable when extended

Question 8

patella

Answer 8

Sesamoid bone in quadriceps femoris tendon

Improves mechanical efficiency by acting as a fulcrum https://www.youtube.com/watch?v=XnYO4TnpTCo

Apex inferiorly, flatter superiorly

Posterior facets

Prone to medial/lateral dislocation

Question 9

Proximal tibia

Answer 9

Flattened and enlarged medial and lateral condyles for weight-bearing and distribution

Separated by raised pair of intercondylar/tibial spines running anterior/posterior

Attachment site for cruciate ligaments/meniscus

Combined to form tibial plateau

Medial tibial condyle larger and stronger

Slightly concave centrally to articulate with femoral condyles

Flattened depression on postero-lateral condyle for fibula head

Tibial tuberosity; attachment for patella ligament/tendon

Question 10

Proximal fibula

Answer 10

Not part of knee joint, not weight bearing

Roughly triangular in cross-section

Head enlarged; attachment site

Tibio-fibular joint is synovial; minimal movement

Question 11

OSSIFICATION CENTRES

Answer 11

DISTAL FEMUR:
PRIMARY: Diaphysis/shaft (7th week in uTERO)
SECONDARY: distal EPIPHYSIS/FEMORAL CONDYLES (~40th week in utero)
Fusion ~16-18 years

PROXIMAL TIBIA:
Primary: diaphysis/shaft (7th week in utero)
Secondary:
proximal epiphysis/tibial plateau (1 year)
Tibial tuberosity apophysis (10-12 years)

Fusion ~16-18 years

PATELLA:
Primary: (3-6 years)
Secondary (normal variant) only in some cases (bi-partite patella)
Fully ossified during puberty

Proximal fibula:
Primary: diaphysis/shaft (8th week in utero)
Secondary: proximal epiphysis/head (3-4 years)
Fusion ~16-18 years

Question 12

menisci

Answer 12

C-shaped fibrocartilage rings on tibial condyles

Attached anteriorly/posteriorly on tibial spines

Increase surface area of articular surface of tibia to improve congruence with femur

Commonly injured/torn

Question 13

Synovial membrane/capsule

Answer 13

Forms intra-articular region of knee

Attaches to tibial/femoral articular surfaces and menisci

Passes anterior to cruciate ligaments

Filled with synovial fluid to act as lubricant to movement

Bone surfaces covered by hyaline cartilage

Friction further reduced by:
several extensions/recesses of capsule
Presence of synovial bursae
Infra-patella (Hoffa’s) fat pad

Supra-patella bursa most significant in knee effusions
Bursitis a common clinical presentation

Question 14

Knee effusions

Answer 14

Caused by increase in fluid within the joint capsule:
Blood
Pus
Synovial fluid
Presents as oval opacity in supra-patella bursa on lateral
Non-specific but In trauma it’s presence is suspicious for ‘injury’

Presence of fat and blood level indicates definite intra-articular fracture: lipohaemarthrosis

Question 15

Fibrous joint capsule

Answer 15

Encloses, Supports, and strengthens the joint

Blends with medial meniscus and collateral ligament

Lateral structures less fixed and more mobile

Connects medial/lateral patella to provide stability

Question 16

ligaments

Answer 16

Number of major and less significant ligaments provide much of the knee’s strength and stability:
Patella ligament( ?tendon)
Collateral (medial/lateral)
Cruciate (anterior/posterior)

mOre likely to rupture in adults than bony injury (opposite in paediatrics)

Question 17

Patella ligament

Answer 17

Continuation of quadriceps femoris tendon

Connects apex of patella and tibial tuberosity

Covered anteriorly/posteriorly to reduce friction:
Superficial/deep infrapatellar bursa
Hoffa’s fat pad

Question 18

Collateral ligaments

Answer 18

Medial (tibial) collateral (MCL)
Flat and broad
Connected to fibrous capsule/meniscus

Lateral (fibular) collateral (LCL):
More like a rope
Separate from capsule by bursa

Prevent medial/lateral movement at knee joint
Consider injury in side impact forces on the knee

Question 19

Cruciate ligaments

Answer 19

‘Cross’ in the intercondylar region

Provide anterior/posterior stability preventing tibia moving

Anterior (ACL):
Prevents anterior movement of tibia
Lateral femoral condyle to anterior tibial spine

Posterior (PCL):
Prevents posterior movement of tibia
Medial femoral condyle to posterior tibial spine

Injury commonly associated with other structures; clinical examination and MRI

Question 20

Neurovasular

Answer 20

Popliteal fossa:
transition between region of thigh and leg
Formed by space between muscles in posterior knee
Neurovascular structure pass through this

Branches from femoral/popliteal artery which divides into anterior/posterior tibial (forms an anastomosis)

Sciatic nerve divides into tibial and common fibular

Small saphenous and tibial veins combine to form femoral vein