L6: Osteology of the Distal Femur, Patella, Tibia and Fibula, Functional anatomy of the knee, Disorders of the Knee Flashcards

Question

What is the neurovascular supply to the knee? What is an important clinical feature to be aware of?

Answer 1

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

Answer 2

Tibial articular surface deepened--> menisci Joint capsule--> support Ligaments and surrounding muscles

Answer 3

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

Answer 4

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

Answer 5

Blood supply from periphery | Flow decreases with age--> avascular by adulthood--> impaired healing after trauma

Answer 6

Divided into three categories Intracapsular ligaments: Cruciate ligaments Extracapsular ligaments: Collateral ligaments, patella ligament Strengthen the capsule: Oblique popliteal ligaments

Answer 7

Anterior and posterior Connect the femur to the tibia Cross over

Answer 8

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

Answer 9

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

Answer 10

Allows synovial membrane to extend beneath the patella | Suprapatella bursa--> small sac filled with synovial fluid

Answer 11

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

Answer 12

Proximal--> apex of patella Distal--> tibial tuberosity continuation of the quadriceps femoris tendon

Answer 13

Found on medial and lateral side of the knee Stabilise knee Prevent excessive medial and lateral angulation of the knee

Answer 14

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

Answer 15

``` 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 ```

Answer 16

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

Answer 17

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

Answer 18

``` 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 ```

Answer 19

Popliteus contracts Lateral (externral) rotation by 5 degrees Allows the knee to flex

Answer 20

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

Answer 21

Means that during extension the patella wants to be displace laterally

Answer 22

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

Answer 23

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

Answer 24

Pectineus Sartorius Quadriceps Femoris--> Rectus femoris, vastus medialis, vastus lateralis and vastus intermedius Iliopsoas--> Psoas major and iliacus--> insert into anterior thigh

Answer 25

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

Answer 26

4 muscles common tendon of insertion - Rectus femoris - Vastus medialis - Vastus lateralis - Vastus intermedius

Answer 27

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

Answer 28

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

Answer 29

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

Answer 30

Generally adductor | Innervation: Obturator nerve--> L2, 3 and 4

Answer 31

``` Gracilis Obturator externus Adductor brevis Adductor longus Adductor magnus ```

Answer 32

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

Answer 33

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)

Answer 34

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)

Answer 35

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)

Answer 36

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

Answer 37

Anatomical region of proximal thigh | Large neurovascular structures pass through

Answer 38

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

Answer 39

From ASIS to the pubic tubercle Acts as flexor retinaculum Supports contents of the femoral triangle during hip flexion

Answer 40

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

Answer 41

MIPA --> Mid-inguinal point= artery Mid way between the ASIS and the symphysis pubis

Answer 42

Fascial compartment containing the femoral artery, femoral vein and femoral canal Femoral nerve outside

Answer 43

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

Answer 44

Superior border--> femoral ring | Femoral septum--> connective tissue layer, lymphatic vessels pierce this layer

Answer 45

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

Answer 46

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

Answer 47

Anterior--> sartorius Lateral--> Vastus medialis Posterior--> Adductor longus and adductor magnus Apex--> adductor hiatus (between adductor and hamstring component of adductor magnus)

Answer 48

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)

Answer 49

Major peripheral nerve of lower limb | Form in lumbar plexus--> posterior division of L2, 3 and 4

Answer 50

- 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

Answer 51

Formed from anterior branchs of L2, 3 and 4

Answer 52

- 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

Answer 53

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

Answer 54

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

Answer 55

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

Answer 56

Deep veins and superficial veins

Answer 57

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

Answer 58

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

Answer 59

Drains tissue fluid, plasma protein and other cellular debris--> lymph Superficial and deep vessels

Answer 60

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

Answer 61

Fewer in number, follow the deep arteries Three main groups--> follow corresponding artery -Anterior tibial -Posterior tibial -Peroneal Enter the popliteal lymph nodes

Answer 62

Everyone Youngster--> play lots of sport Middle aged Elderly--> worn out joints, degenerative conditions, arthritis

Answer 63

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)

Answer 64

Femur --> Proximal, mid-shaft or supracondyle Tibia--> plateau fractures Patella

Answer 65

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

Answer 66

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

Answer 67

Surgical fixation | Tractation splint--> immoblise limb and keep it straight--> reduced death rate from 100% to 40%

Answer 68

Usually children (high impact activity) or elderly Usually significant displacement of fracture segments Complication--> popliteal artery may become involved in significant displacement

Answer 69

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

Answer 70

-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

Answer 71

``` Bipartite patella (in two parts) Failure of union of secondary ossification centre within main body of patella ```

Answer 72

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

Answer 73

Generalise ligament laxity Weakness of quadriceps muscle--> especially VMO Shallow trochlear (patellofemoral) groove--> with flat lateral lip Long patella ligament Previous dislocations

Answer 74

Extend the knee Manually reduce the patella Immobilisation whilst healing takes place Physiotherapy to strengthen VMO

Answer 75

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

Answer 76

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

Answer 77

Injury to ACL, MCL, and MM Strong force applied to lateral aspect MCL adhered to MM so MM injured to

Answer 78

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

Answer 79

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)

Answer 80

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

Answer 81

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

Answer 82

Accumulation of fluid inside the knee joint--> never normal Acute <6hrs--> bleeding Delayed >6hrs--> reactive synovitis, inflammation of the synovium

Answer 83

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)

Answer 84

Inflammation of bursa

Answer 85

Pre-patella bursae Infrapatella bursae Pes anserinus bursae Suprapatella bursae

Answer 86

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

Answer 87

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

Answer 88

``` 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 ```

Answer 89

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

Answer 90

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

Answer 91

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)

Answer 92

Initially--> Comes and goes --> chronic low level pain --> flares up Develops--> Pain precipitated by activities Pain and stiffness worse after prolonged inactivity or rest

Answer 93

Affects 12% of population and 35% >75years | Uni, bi or tri- compartmental--> can affect medial and lateral femorotibial and patellofemoral compartments

Answer 94

Age, gender (female), previous trauma, obesity, family history, other conditions that affect joint

Answer 95

Treatment ladder - Strengthen vastus medialis--> reduce instability - Anagleasia, weight loss, activity modification - Surgery--> total knee replacement (110,000 annually in UK, 1200 in Leic)

Answer 96

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

Answer 97

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

Answer 98

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

Answer 99

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