L6: Osteology of the Distal Femur, Patella, Tibia and Fibula, Functional anatomy of the knee, Disorders of the Knee Flashcards
Why does the shaft of the femur descend at an angle?
Brings the knee closer to the body’s centre of gravity
Increasing the stability
On the posterior side of the femur what is the roughened ridge called?
Linea Aspera
What does this posterior line start as on the medial side and the lateral side?
Medial side–> Pectineal line
Lateral side–> Gluteal Tuberosity (GMax insertion)
Distally what does the linear aspera become on the medial and lateral side?
Medial supracondylar line –> ends at adductor tubercle
Lateral supracondylar line–> ends at lateral femoral condyle
What is the name of the fossa formed by the widening of the medial and lateral supracondyle lines?
The popliteal fossa
What forms part of the knee articular joint?
Femur–> medial and lateral femoral condyle
Patella
Tibia
Which of the femoral condyles of the femur is bigger?
The medial condyle
Bears more weight
Centre of mass passes medial to knee joint
What is the name of the groove that the patella site in?
Trochlear (patellofemoral) groove
Anterior surface of distal femur
What do the inferior and posterior surface of the femoral condyles articulate with?
Menisci of the knee
Tibia
What stops the patella from moving laterally out of place when the leg bends or straightens? (patella tracking)
Prominent lateral femoral condyle
What type of bone is the patella classified as? Describe its basic shape?
Sesamoid bone
Triangular shape (upside down)
Base–> forms superior surface
Apex–> forms inferior surface
What is the attachment sites of the patella? What does it articulate with?
Superiorly attached to the quadriceps tendon
Inferiorly attached to the patella ligament (not tendon attaches bone to bone)–> inserts onto tibial tuberosity
Articulates with femur
Medial facet–> medial femoral condyle
Lateral facet–> lateral femoral condyle
What is the function of the patella?
Increase mechanical efficiency of Quadriceps muscle by 33-50%–> allows muscle to cross the anterior aspect of knee by acting as a falcrum
Protection–> protects anterior aspect of knee
Reduces frictional force between quads and femoral condyles during extension of the leg
What is the more common name for the tibia?
Shinbone
Describe the key features at the proximal end of the tibia?
Proximal tibia–> Widened–> Medial and lateral condyle
Forms tibial plateau–> articulates with femoral condyles
Intracondylar area–> Centre of area is intracondylar eminence
Either side–> medial and lateral intracondylar tubercles
Head of fibula–> proximal tibofibular joint
What is the importance of the intracondylar eminence and tubercles?
Attachement site for anterior cruciate ligament and menisci
Intracondylar tubercles articulate with intracondylar fossa (femur)
Posterior cruciate ligament attaches to the posterior edge of the intercondylar area
Describe the anatomy of the shaft of the tibia?
Prism shaped
- Anterior border–> palpable down anterior surface of the leg
- -> tibial tuberosity–> insertion of patella ligament
- Posterior border–> Soleal line–> origin of the soleus muscle, line extends inferomedially blending with medial edge of tibia
- Lateral border–> interosseous border–> interosseous membrane that binds the tibia and fibilar together
Describe the anatomy of the distal part of the tibia?
Widens to assist with weight bearing
Medial malleolus –> inferior bony projection, articulates with tarsal bone, forms part of ankle joint
Laterally–> fibular notch, fibula bound to tibia–> Distal/inferior tibiofibular joint
What is the main function of the fibular?
Attachment site for muscles
What are the three main articulations of the fibular?
Proximal tibiofibular joint–> articulates with lateral condyle of tibia
Distal tibiofibular joint–> articulates with fibular notch of tibia
Ankle joint–> articulates with talus bone of foot
Describe the anatomy of the fibular?
Proximal end–> enlarged head, facet for articulation with the lateral condyle of tibia
Shaft–> anterior, posterior and lateral surfaces, face respective compartment
Distal end–> continues inferiorly –> lateral malleolus
More prominent than medial malleolus of the tibia–> can be palpated
What is an important nerve associated with the fibular?
Common peroneal (fibular) nerve winds around posterior and lateral surface of neck of fibula–> vulnerable to damage in proximal fibular fracture
What type of joint is the knee joint?
Hinge-type synovial joint
Flexion and extension with small degree of medial and lateral rotation
Surfaces lined with hyaline cartilage
What bones form the knee joint? What are the main articulations?
Patella, femur and tibia
Tibiofemoral–> Medial and lateral condyles of femur, articulate with medial and lateral tibial condyles –> weightbearing joint
Patellofemoral–> Patella articulates with the femur at the trochlear (patellofemoral) groove
What is the neurovascular supply to the knee? What is an important clinical feature to be aware of?
Blood supply–> Genicular anastomoses–> supplied by genicular branches of the femoral and popliteal arteries
Clinical relevance–> If popliteal artery occluded–> genicular anastomoses dilate to maintain blood supply to leg
Nerve supply–> Hiltons law–> Nerves that cross the knee joint–> femoral, tibial and common peroneal (common fibular) nerves
How is the stability of the knee improved?
Tibial articular surface deepened–> menisci
Joint capsule–> support
Ligaments and surrounding muscles
What are the menisci and what are there functions?
Medial and lateral menisci
Fibrocartilagenous structures- C shaped- thicker peripherally than centrally
Deepen the articular surfaces of the tibia–> ↑ stability
Act as shock absorbers –> ↑ SA, dissipate forces
What are the attachment sites of the menisic?
Intracondylar eminence
Medial meniscus–> attached peripherally to medial (tibial) collateral ligament and joint capsule
Lateral meniscus–> small no attachment to lateral (tibial) collateral ligament –> fairly mobile, but attached to the medial femoral condyle by the posterior meniscofemoral ligament
Attached anteriorly by the transverse ligament of the knee
Peripheral rims loosely attached to the joint capsule and tibia by the coronary ligaments
What is the blood flow to the menisci?
Blood supply from periphery
Flow decreases with age–> avascular by adulthood–> impaired healing after trauma
What are the major ligaments in the knee?
Divided into three categories
Intracapsular ligaments: Cruciate ligaments
Extracapsular ligaments: Collateral ligaments, patella ligament
Strengthen the capsule: Oblique popliteal ligaments
What are the cruciate ligaments?
Anterior and posterior
Connect the femur to the tibia
Cross over
What is the proximal and distal attachment of the ACL? What is its function?
Hands in pocket
Proximal: Posterolateral aspect of the femoral intercondylar fossa (femur)
Distal: Anterior aspect of the intercondylar eminence of the tibia, and medial meniscus
Passes anteromedially
Function: resists anterior translation and medial rotation of tibia in relation to the femur
What is the proximal and distal attachment of the PCL? What is its function?
Proximal: Medial border and roof of intercondylar fossa (femur)
Distal: Posterior intercondylar area of tibia
Passes posteriolaterally
Function: Stabiliser of weight-bearing flexed knee
Prevents femur sliding off anterior edge of tibia
Why is the joint capsule deficient anteriorly?
Allows synovial membrane to extend beneath the patella
Suprapatella bursa–> small sac filled with synovial fluid
What strengthens the capsule on the medial, lateral and posterior surface?
Medial and lateral–> inferior fibres from the vastus medialis and lateralis (respectively)
Posteriorly–> Oblique popliteal ligament –> continuation of fibres from the semimembranosus tendon in superolateral direction from main insertion on the medial tibial condyle
What is the proximal and distal attachments of the patella ligament?
Proximal–> apex of patella
Distal–> tibial tuberosity
continuation of the quadriceps femoris tendon
What are the collateral ligaments?
Found on medial and lateral side of the knee
Stabilise knee
Prevent excessive medial and lateral angulation of the knee
What are the proximal and distal attachments of the collateral ligaments?
Medial collateral ligament–> wide flat ligament
Proximal–> Medial epicondyle of femur
Distal–> Medial condyle of tibia, and medial meniscus
Function–> resits lateral angulation of tibia on femur
Wider but weaker
Lateral collateral ligament–> Thinner and rounder
Proximal–> Lateral epicondyle of femur
Distal–> Depression on lateral surface of fibular head
Reinforced by the iliotibial tract
Function–> Resists medial angulation of tibia on femur
Weak in isolation, works as part of posterolateral corner with arcuate ligament and popliteus tendon
What is a bursae? What is the function
Small sac lined with synovial membrane Containing synovial fluid Cushion between the bones and tendon Reduce friction Allows free movement Either communicating or non communicating with the joint cavity
What are the names of the bursae within the knee? Where are they located?
6 Bursae
1) Suprapatella bursae –> extension of synovial cavity, between the quadraceps femoris muscle and femur
2) Prepatella bursae–> anterior surface of patella and skin
3) Superficial (or subcutaneous) infrapatella bursae–> between patella ligament and skin
4) Deep infrapatella bursae–> between tibia and patella ligament
5) Semimembranosus burase–> posterior, between semimembranous muscle and medial head of gastrocnemius
6) Subsartorial (pes anserinus) bursa–> between pes anserinus (common insertion of sartorius, gracillis and semitendinosus) and medial tibial condyle
What movements are possible at the knee joint? Which muscles makes these movements possible?
4 movements
1- Extension –> Quadriceps femoris (rectus femoris, vastus medialis, vastus lateralis, vastus intermedius)
2- Flexion –> Hamstrings (biceps femoris, semitendinousus, semimembranosus), gracilis, sartorius, popliteus, plantaris and gastrocnemius
3- Lateral (external) rotation–> biceps femoris
4- Medial (internal) rotation–> semimebranous, semitendinosus, gracilis, sartorius and popliteus
What happens when the knee is fully extended with the foot on the ground?
Knee locks 5 degree of medial (internal) rotation Cruciate ligaments tighten, lower limb becomes a solid column Weight bearing Thigh and leg muscles can relax briefly
How is the knee unlocked?
Popliteus contracts
Lateral (externral) rotation by 5 degrees
Allows the knee to flex
What is the Q angle?
The angle between the line of pull of the quadriceps tendon and the patellar ligament
Bigger hip= > Q angle more likely to have knee problems
What does the Q angle mean?
Means that during extension the patella wants to be displace laterally
What prevents this lateral displacement of the patella?
Two things:
- Deep trochlear (patellofemoral) groove with lateral femoral condyle more prominent anteriorly
- Vastus medialis obliquus–> inferior fibre of vastus medialis insert more distally and horizontally then the vastus lateralis–> contraction prevents displacement
What is the nerve innervation, general function and blood supply to the anterior compartment of the thigh?
Femoral nerve L2-L4
Generally extends the leg at the knee joint
Arterial supply: femoral artery- lateral and medial circumflex arteries and profunda fermoris branch
What are the muscles of the anterior thigh?
Pectineus
Sartorius
Quadriceps Femoris–> Rectus femoris, vastus medialis, vastus lateralis and vastus intermedius
Iliopsoas–> Psoas major and iliacus–> insert into anterior thigh
What is the origin and insertion of the iliopsoas muscle? What is the function? What is the innervation?
Psoas major and iliacus–> separate origins but common insertion and function hence considered iliopsoas
Origin
- Psoas major–> transverse process of T12- L5 and lateral margins of IVD
- Iliacus–> Iliac fossa of pelvis
Insertion
- Lesser trochanter (femur)
Function
- Flexes the lower limb at hip
- Lateral rotation of femur
Innervation
- Psoas major–> Anterior rami of L1-3
- Iliacus–> femoral nerve
What are the muscles of the Quadriceps femoris?
4 muscles common tendon of insertion
- Rectus femoris
- Vastus medialis
- Vastus lateralis
- Vastus intermedius
What is the origin and insertion of the Quadriceps femoris muscles? What is the function? What is the innervation?
Origin
- Rectus femoris –> originated as two tendons
- -> anterior (straight): AIIS
- -> posterior (reflected): Groove above the rim of the acetabulum - Vastus medialis–> Intertrochanteric line of the femur
- -> medial lip of the linear aspera - Vastus intermedius–> Anterior and lateral surface of the femoral shaft
- Vastus lateralis–> Greater trochanter
- -> Lateral lip of linear aspera
Insertion
- Common tendon–> Quadriceps tendon into the base of patella
Function
- RF–> Only quad muscle to cross hip and thigh
- -> Flexes thigh at hip
- -> Extends leg at knee - VM–> Extension of leg at knee
- -> Stabilised the patella
- -> VMO fibres prevent lateral displacement by contracting - VI–> Extends at knee
- -> Stabilise patella
- VL–> Extends at knee
- -> Stabilise patella
Innervation
- Femoral nerve
What is the origin and insertion of the Sartorius muscle? What is the function? What is the innervation?
Positioned superficially
Origin: ASIS
Insertion: Pes anserinus onto medial aspect of proximal tibia
Function: Flexs, abducts and laterally (externally) rotates thigh –> when knee is fixed
–> Extends and medially (internally) rotates tibia at knee–> when hip is fixed
Innervation : Femoral nerve
What is the origin and insertion of the Pectineus muscle? What is the function? What is the innervation?
Flat muscle–> forms base of femoral triangle
Origin: Pectineal line on anterior surface of superior pubic ramus
Insertion: Pectineal line on posterior surface of proximal femur
Function: Adducts and flexed thigh at hip
Innevation: Femoral nerve and sometime branch of obturator nerve
What are the general function of the medial muscle of the thigh and the innervation?
Generally adductor
Innervation: Obturator nerve–> L2, 3 and 4
What are the muscles of the medial compartment of the thigh?
Gracilis Obturator externus Adductor brevis Adductor longus Adductor magnus
What is the origin and insertion of the Gracilis muscle? What is its function? What is its innervation?
Most superficial and medial
Crosses hip and knee
Origin: Inferior pubic ramus and body of pubis
Insertion: Medial surface of proximal tibia–> between tendons of sartorius (anteriorly) and semitendinosus (posteriorly) –> Pes anserinus
Function: Adducts thigh and flexes leg at knee
Innervation: Obturator nerve L2-L4
What is the origin and insertion of the Obturator externus muscle? What is its function? What is its innervation?
Sometimes considered deep muscle of the hip
Origin: External surface of the obturator membrane
Insertion: Posterior to neck of femur onto posterior aspect of greater trochanter
Function: Adduction and lateral (external) rotation
Innervation: Obturator nerve (L2, 3 and 4)
What is the origin and insertion of the Adductor brevis muscle? What is its function? What is its innervation?
Short muscle, proximal and deep to adductor longus
Between anterior and posterior divisions of the obturator nerve
Origin: Body of pubis and inferior pubic ramus
Insertion: Linear aspera, proximal to adductor longus
Function: Adduct the thigh
Innervation: Obturator (L2, 3 and 4)
What is the origin and insertion of the Adductor longus muscle? What is its function? What is its innervation?
Large, long flat muscle, partially overlies the adductor brevis and magnus
Forms medial border of femoral triangle
Origin: Body of pubis
Insertion: expands as fan shape inserts onto middle third of linear aspera
Function: Adducts the thigh
Innervation: Obturator nerve (L2, 3 and 4)
What is the origin and insertion of the Adductor magnus muscle? What is its function? What is its innervation?
Largest muscle in medial thigh
Posterior to other muscles
Functionally divided into two: Adductor part and hamstring part
Origin: Adductor: Inferior ramus of pubis and ischium
: Hamstring component: Ischial tuberosity
Insertion: Adductor: Linera aspera
: Hamstring component: adductor tubercle and medial supracondylar line of femur
Insertion separated by the adductor hiatus–> femoral vessels pass
Function: Both adduct the thigh, adductor part: flexes thigh, hamstring part: extends
Innervation: Adductor part: Obturator nerve (L2, 3 and 4)
: Hamstring part: tibial component of sciatic nerve
What is the femoral triangle?
Anatomical region of proximal thigh
Large neurovascular structures pass through
What forms the borders of the femoral triangle?
Superior border: Inguinal ligament
Lateral border: Medial border of sartorius muscle
Medial border: Medial border of adductor longus muscle
Roof: anteriorly, formed by fascia lata
Base: posteriorly, pectineus, iliopsoas and adductor longus muscle
What is the inguinal ligament?
From ASIS to the pubic tubercle
Acts as flexor retinaculum
Supports contents of the femoral triangle during hip flexion
What structure are contained within the femoral triangle? What is a mnemonic to remember the contents?
Major neurovascular structures of the lower limb
From lateral to medial:
-Femoral nerve
-Femoral artery
-Femoral vein –> great saphenous vein drains into the femoral vein in the triangle
-Femoral canal–> structure contains deep lymph nodes and vessels
NAVEL– Nerve, Artery, Vein, Empty space, Lymphatics
Empty space–> important to cope with the changes in flow of the lymphatics and vein
How can you identify the location of the femoral artery?
MIPA
–> Mid-inguinal point= artery
Mid way between the ASIS and the symphysis pubis
What is contained within the femoral sheath?
Fascial compartment containing the femoral artery, femoral vein and femoral canal
Femoral nerve outside
What is the femoral canal? What are the borders?
Anatomical compartment, 1.3cm long, smallest and most medial part of femoral sheath
Medial border: Lacunar ligament (connects inguinal ligament to pectineal ligament)
Lateral border: Femoral vein
Anterior border: Inguinal ligament
Posterior border: Pectineal ligament (extension of lacunar, on superior ramus of pubic bone (pectineal line)), the superior ramus of pubic bone and pectineus muscle
Where does the femoral canal open? What covers the femoral canal opening?
Superior border–> femoral ring
Femoral septum–> connective tissue layer, lymphatic vessels pierce this layer
What is contained in the femoral canal? Why is the space necessary?
Lymphatic vessels–> drain deep inguinal lymph nodes
Deep lymph node–> lacunar node
Empty space–> allows distension of femoral vein–> increased venous return or due to increased intra-abdominal pressure
Loose connective tissue
What is the adductor canal or subsartorial canal?
Narrow conical tunnel in thigh
15cm long
Extends from apex of femoral triangle to the adductor hiatus of adductor magnus
Passage way for structures between the anterior thigh and posterior leg
What are the borders of the adductor canal?
Anterior–> sartorius
Lateral–> Vastus medialis
Posterior–> Adductor longus and adductor magnus
Apex–> adductor hiatus (between adductor and hamstring component of adductor magnus)
What passes through the canal?
Superficial femoral artery and femoral vein–> into popliteal fossa become popliteal artery and vein
Nerve to vastus medialis and saphenous nerve (largest cutaneous branch of femoral nerve)
What is the femoral nerve?
Major peripheral nerve of lower limb
Form in lumbar plexus–> posterior division of L2, 3 and 4
Describe the course of the femoral nerve?
- Descend from lumbar plexus in abdomen
- Passes through fibres of the psoas major muscle
- Exits psoas major at inferior part of the lateral border passing behind the fascia iliac
- Passes behind midpoint of inguinal ligament –> splits into anterior and posterior division 4cm below inguinal ligament
- Through femoral triangle lateral to femoral vessels in femoral sheath
- Anterior branch supplies pectineus, sartorius and iliacus, posterior supplies Quadriceps femoris, become saphenous nerve
- Gives off articular branches to hip and knee
- Within the triangle gives of anterior cutaneous branches–> skin on anteriomedial thigh
- Terminal cutaneous branch of femoral nerve is the saphenous nerve (posterior division)
- Continues through adductor canal to supply the skin on medial side of leg and the foot sometimes as far as the big toe
What is the obturator nerve?
Formed from anterior branchs of L2, 3 and 4
What is the course of the obturator nerve?
- Descend through fibres of psoas major, emerges from medial border
- Posterior to common iliac arteries and laterally along the pelvic wall to the obturator foramen
- Enter thigh through the obturator canal, split into anterior and posterior branches
- Anterior division descends anterior to adductor brevis and posterior to adductor longus and pectineus
- Gives off branches to the adductor longus and brevis and gracilis–> rare cases also pectineus (normally femoral nerve)
- Pierces fascia lata to become cutaneous branch of obturator nerve and supply skin over middle part of medial thigh
- Posterior division descend through the obturator externus muscle (supplies it)
- Passes posterior to adductor brevis, anterior to adductor magnus supplies adductor brevis and adductor part of adductor magnus
What is the arterial supply to the lower limb?
Femoral artery main artery
Common femoral artery continuation of external iliac artery–> name changes as it passes under the inguinal ligament and enters the femoral triangle
What happens to the common femoral artery in the femoral triangle?
CFA–>Branches giving off profunda femoral artery (deep femoral artery)
Profunda femoral artery branches:
- Lateral femoral circumflex artery (LFCA)–> anterolateral aspect of proximal femur–> extracaspular arterial ring of neck and head of femur
–> desending branch supplies some lateral muscle of thigh
- Medial femoral circumflex artery (MFCA)–> posterolateral aspect of proximal femur–> extracapsular arterial ring of neck and head of femur
- Perforating branches–> 3/4 branches, perforate adductor magnus muscle–> supply muscle of medial and posterior thigh
CFA continues as superficial femoral artery–> enter adductor canal supplying anterior thigh muscles–> passes through adductor hiatus–> enter posterior compartment of thigh –> proximal to knee joint–> now called popliteal artery
What other arteries supply the lower limb?
Obturator artery–> internal iliac artery–> enters medial thigh throuhh obturator canal
Superior and inferior gluteal arteries–> internal iliac artery–> greater sciatic foramen–> gluteal region
Superior–> superior to piriformis
Inferior–> inferior to piriformis–> also contributes to posterior thigh
What are the veins of the lower limb?
Deep veins and superficial veins
What are the deep veins of the lower limb?
Deep
–> popliteal vein enters via adductor hiatus become femoral vein–> ascends in the adductor canal
–> profunda fermoris vein follow the artery–> via
perforating veins drains the thigh muscles –> distal
part of femoral vein
–> femoral vein deep to inguinal ligament (medial to artery) –> become external iliac vein
Gluteal region–> drained by inferior and superior gluteal–> internal iliac vein
Obturator vein–> drains medial compartment of thigh–> obturator foramen–> internal iliac vein
What are the superficial veins of the lower limb?
In subcutaneous tissue
Two major superficial veins: Great (long) saphenous vein and small (short) saphenous vein
Great saphenous vein–> dorsal venous arch of foot and dorsal vein of great toe–> anterior to medial mallelous–> medial aspect of tibia–> posterir to medial aspect of tibia–> hand breath posterior to medial border of patella–> medial thigh–> pierce saphenous opening of fascia lata 1-3cm distal to inguinal ligament–> femoral vein at saphenofemoral junction in femoral triangle
receives many small tributaries as it ascends
Small (short) saphenous vein –> dorsal venous arch of foot and dorsal vein of little toe–> posterior to lateral mallelous–> lateral border of Achilles (calcaneal) tendon–> ascends posterior leg–> between two heads of gastrocnemius–> popliteal vein at saphenopopliteal junction in popliteal fossa
What is the lymphatic system in the lower leg?
Drains tissue fluid, plasma protein and other cellular debris–> lymph
Superficial and deep vessels
What is the superficial lymphatic drainage?
Superficial lymphatics–> medial and lateral vessels
- -> medial –> follow course of great saphenous vein –> inferior group of superficial inguinal lymph nodes in the femoral triangle
- -> lateral–> small saphenous vein–> drain into either popliteal lymph nodes (follow femoral vein–> deep inguinal nodes) or cross to join medial group–> superficial inguinal lymph nodes
What is the deep lymphatic drainage?
Fewer in number, follow the deep arteries
Three main groups–> follow corresponding artery
-Anterior tibial
-Posterior tibial
-Peroneal
Enter the popliteal lymph nodes
Who gets knee problems?
Everyone
Youngster–> play lots of sport
Middle aged
Elderly–> worn out joints, degenerative conditions, arthritis
Why are knee disorders important to detect and treat?
Major weight bearing joint–> prone to damage
Required for walking (health and fitness)
Reduces mobility –> predisposition to falls, weight gain,
Disability
Inability to work
–> social isolation, depression (psychosocial impacts)
What parts of the knee can be fractured?
Femur –> Proximal, mid-shaft or supracondyle
Tibia–> plateau fractures
Patella
What causes the femur to fracture?
Requires lots of force (children and young adults)
–> Road traffic accidents
–> Falls from a height
Elderly–> low velocity injuries–> falling over etc… especially if they have osteoporotic bones
What are the problems associated with femoral shaft fractures?
Muscularture can cause deformaties
–> Gluteal muscles contract pull greater trochanter superiorly –> proximal femur abducted
–> Distal section adducted due to adductor muscles and extended due to gastrocnemius
Swollen thigh –> closed femoral fracture blood loss 1500ml, open fractures can be double –> hypovolaemic shock
How are femoral shaft fractures treated?
Surgical fixation
Tractation splint–> immoblise limb and keep it straight–> reduced death rate from 100% to 40%
What happens in distal femoral shaft injuries (supracondylar)?
Usually children (high impact activity) or elderly
Usually significant displacement of fracture segments
Complication–> popliteal artery may become involved in significant displacement
What happens in tibia plateau fractures?
High energy injuries
Axial loading with valgus or varus angulation–> fracture of condyle
Affect articular surface of tibia–> uni- or bicondylar
Lateral fracture most common
Articular cartilage always damaged
Usually develop post-traumatic osteoarthritis
What is a patellar fracture? What test can be done? How are they treated?
-Caused by direct impact or indirectly by eccentric contraction of quadriceps femoris muscle (muscle is contracting joint is extending)
-Blood supply by inferior pole
-Examination –> palpable defect
–> Lift leg in extended position–> quadriceps femoris disrupted unable to do so–> main extensor of leg at knee
Displace patella fractures require reduction and surgical fixation
Undisplaced–> splint and crutches no surgery required
What is sometimes mistaken for a patella fracture on an X-ray? Why does this occur?
Bipartite patella (in two parts) Failure of union of secondary ossification centre within main body of patella
Patella dislocation what is it? Why does it happen? What causes it?
Patella displaced usually laterally
(Sublaxation–> partial displacement)
Q angle between the line of pull of quadriceps tendon and patella ligament–>patella pulled laterally
VMO, prominent lateral condyle–> usually prevent lateral displacement
Physical trauma –> twisting injury in slight flexion, direct blow to knee
Athletic teenagers often affected–> Internal rotation of femur on planted foot whilst flexing the knee
What factors can predispose to patella dislocation?
Generalise ligament laxity
Weakness of quadriceps muscle–> especially VMO
Shallow trochlear (patellofemoral) groove–> with flat lateral lip
Long patella ligament
Previous dislocations
How is patella dislocation treated?
Extend the knee
Manually reduce the patella
Immobilisation whilst healing takes place
Physiotherapy to strengthen VMO
What causes meniscal injuries? What are the symptoms? What are the clinical signs? How are they treated?
Tear due to sudden twisting of weight-bearing knee during flexion Patient–> intermittent pain localised to joint line, knee clicking, catching, locking or sensation of giving way
Swelling–> delayed –> reactive effusion or not at all
Mensici are avascular (except periphery)
Haemarthrosis rare–> peripheral tear
Chronic effusion–> synovitis–> inflammation of synovial membrane
Examination–> joint tenderness, resistricted motion due to pain (or swelling), mechanical block to motion–> menisci fragments in between articular surfaces
Treatment–> acute–> surgical- meniscectomy or meniscal repair, chronic–> degenerative process, conservation management as effective
What happens during collateral ligament injury?
Medial and lateral collateral ligaments
Medial injury–> Distal end varus angulation–> Knee moves medially
Lateral injury–> Distal end valgus angulation–> Knee moves laterally
Medial tibial plateau is deeper and more stable than lateral so if lateral collateral ligament goes (less common) knee very unstable
Immediately after injury–> pain and swelling, unstable joint
What is the unhappy triad?
Injury to ACL, MCL, and MM
Strong force applied to lateral aspect
MCL adhered to MM so MM injured to
Compare and contrast ACL and PCL injury?
ACL–> quick deceleration, hyperextension, rotational injury or larger force to back of flexed knee
PCL–> knee flexed large force to anterior tibia displacing it, or fall on flexed knee with foot plantarflexed tibia hits ground first pushed backwards, sever hyperextension
ACL–> posterolateral to anteriomedial direction, prevents medial rotation of tibia when knee is extended–> anterolateral rotatory instability
ACL treatment–> conservation management for people with low functional demands in knee, surgical reconstruction for those with high demands
PCL treatment–> Conservation management with bracing and rehabilitation
How can you test for ACL and PCL injuries?
Anterior and posterior drawer test (flex 90 degrees, pull tibia forward or push back see if it moves)
ACL–> Lachmans test (place hand on femur, pull tibia forwards see how much movement)
What happens if you dislocate your knee? What is associated?
Uncommon injury
3/4 ligaments (ACL, PCL, MCL, LCL) ruptured
High energy trauma
Associated arterial injury common–> popliteal artery–> unmobile–> tethered proximally where it enters popliteal fossa at adductor hiatus and distally where it exits the popliteal fossa by passing under tendious arch of soleus muscle
Maybe ruptured–> haematoma
Crushed–> traction injury–> thrombotic occlusion
Reduction of knee joint –> assess vasculature of the leg
What can cause swelling around the knee?
Bony–> Osgood-Schlatters-Disease
Soft tissue–>
-Localised –> enlarged popliteal lymph node
-Generalised–> Lymphodema of lower limb
Fluid–>
-Inside the joint= effusion
-Outside the joint= soft tissue haematoma
What does knee effusion mean?
Accumulation of fluid inside the knee joint–> never normal
Acute <6hrs–> bleeding
Delayed >6hrs–> reactive synovitis, inflammation of the synovium
What are the classification of knee effusion?
Haemoarthrosis–> Blood in joint–> ACL rupture until proven otherwise
Lipohaemarthrosis–> blood and fat in joint–> fracture until proven otherwise (fat appears darker on x-ray)
What is bursitis?
Inflammation of bursa
Which bursa are commonly inflamed?
Pre-patella bursae
Infrapatella bursae
Pes anserinus bursae
Suprapatella bursae
What happens in pre-patella bursitis?
Between skin and patella
No communication with synovial joint therefore minimal fluid
Inflammation–> increase in synovial fluid
Repetitive trauma–> Housemaid’s Knee–> Kneeling
Pain, swelling, difficult to walk
What is Infrapatella bursitis?
Two bursae
1–> inferior to patella between skin patella tendon
2–> deep to patella tendon and superfical to tibia –> deep infrapatella bursae
Bursitis commonly affects superficial bursae
Repeated microtrauma
Clergyman’s knee–> more upright postion of kneeling
What is suprapatella bursitis and knee effusion?
Bursae is extension of synovial cavity Therefore knee effusion often present in suprapatella pouch Usually sign of pathology in knee --> osteoarthritis --> Rheumatoid arthritis --> Infection --> Gout and pseudogout --> Microtrauma
What is a semimembranosus bursitis?
Indirect consequence of swelling in knee
Semimembranosus bursae located beneath deep fascia of popliteal fossa–> between semimembranosus head and gastrocnemius (medial head) muscle
Attached to posterior capsule–> may communicate through small opening
Inflamed knee–> Effusion–> swlling
Popliteal cyst or Bakers cyst
What is Osgood-Schlatters Disease? Who is it common in? How is it treated?
Inflammation at apophysis, site of insertion, of patellar ligament onto tibial tuberosity
Teenagers play sport–> running and jumping–> localised pain and swelling
Bilateral in 20-30% cases
Intense knee pain
Resolves with rest and ice
Resolves when apophysis fuse–> prominant tibial tuberosity remains
What is osteoarthritis of the knee? What are the symptoms?
Loss of articular cartilage–> bones rub–> increased friction felt as crepitus (bones grating on each other)–> effusion–> swelling–> reduced movement
Symptoms
- Pain
- Stiffness
- Swelling
- Giving way–> muscle weakness–> instability of joint
Deformity of the knee–> varus deformity, valgus deformity or fixed flexion deformity (knee cannot be extended fully)
How does the pain develop during osteroarthritis?
Initially–> Comes and goes –> chronic low level pain –> flares up
Develops–> Pain precipitated by activities
Pain and stiffness worse after prolonged inactivity or rest
How common is osteoarthritis?
Affects 12% of population and 35% >75years
Uni, bi or tri- compartmental–> can affect medial and lateral femorotibial and patellofemoral compartments
What are the risk factors associated with osteoarthritis?
Age, gender (female), previous trauma, obesity, family history, other conditions that affect joint
What is the treatment for osteoarthritis?
Treatment ladder
- Strengthen vastus medialis–> reduce instability
- Anagleasia, weight loss, activity modification
- Surgery–> total knee replacement (110,000 annually in UK, 1200 in Leic)
What is septic arthritis of the knee?
Invasion of joint space by micro-organisms
Differs from reactive arthritis–> sterile inflammatory process–> result of extra-articular infection
Common micro-organism–> Staphylococcus aureus
Bacteria damages cartilage–> neutrophils–> inflammatory cytokines and other products–> Hydrolysis of collagen and proteoglycans
What are the risk factors for septic arthritis?
Extremes of age, diabetes mellulitis, rheumatoid arthritis, immunosupression, intravenous drug abuse
Prosthetic joints at risk
–> operative contamination
–> haematogenous spread from distant infective focus
–> Delayed wound healing
–> Biofilm produced by Staph. epidermis–> protects against host defence and antibiotics
–> Polymethacrylate cement used in replacement–> inhibit WBCs
What symptoms do patients with septic arthritis present with? What should be examined?
Fever (40-60%)
Pain (75%)
Reduced range of motion
Symptoms usually evolve
Rigor (cold with shivering accompanied by rise in temperature) 20% cases
Examined–> erythema (redness) and swelling (90%), warmth, tenderness, and limitation of active and passive range of motion
Prosthetics–> signs minimal
What should be done is suspected septic arthritis?
Aspiration of joint immediately
Sent for urgent microscopy, culture and sensitivity screening
High morbidity, 50% patients have decreased range of motion or chronic pain after infection has resolved
