Week 5 The knee joint Flashcards
What are the acute injuries of the knee are presented to A&E?
Usually caused by Sports, fall, elderly
Fracture
Tear, sprain of ligament, soft tissue and cartilage
What acute swelling/pain can you get of the knee?
Acute gout or flare of osteoarthritis or rheumatoid arthritis
Septic joint
What are common caues of chronic knee pain/swelling?
Osteoarthritis or bursitis
What can severe damage of the knee cause?
Can result in reduction in movement, poor slep and reduced quality of life.
What type of joint is a knee joint?
Synovial hinge joint
What 3 bones are invovled in the knee joint?
Distal femur
Patella
Proximal tibia
What are the 3 articulations formed by the knee joint?
2 femorotibial –> lateral and medial
1 femorpatellar
Is the fibula part of the knee joint?
No it is not–> articulates with the tibia though
What are the expansions of the distal femoral called?
Lateral femoral condyle on the lateral side
Medial femoral condyle on the medial side
What does the lateral and medial femoral condyle articualte with?
They articualte with the lateral and medial tibial plateaus respectively of the tibia.
What are the movements of the knee joint?
Flexion
Extension
Medial rotation of leg when knee joint flexed 90 degrees
Lateral roation of leg when knee is flexed 90 degrees
When can knee roate?
Rotation can only occur when the knee is flexed and the collateral ligaments are relaxed
When do you loose some knee flexion?
When the pelvis is extended due to loss of tension on hamstring
what is locking of the knee?
As the knee joint aproaches full extension the femur undergoes few degrees of rotation on the tibia.
What is the effect of locking of the knee on the thigh muscles?
The locking of the knee is very stable and therefore allows the thigh muscles to relax
How is the knee joint unlocked?
The knee is unlocked by the popliteus muscle rotating the femur laterally
Where is the popliteal fossa and what is contained with in?
Is a space found at the back of the knee joint and contaisnt the popliteal artery
What are the slight expansions of the proximal tibia?
Medial and lateral tibial condyles
Is flexion or extension of the knee joint most stable? Explain why
Extension is most stable because the tibia and femur have the best fit –> most congruence
However in flexion there is least congruence –> why most injuries happen when knee is flexed
What deepens the plateaus?
The tibial plateaus are deepened by 2 plates of fibrocartilage – the menisci
Why are the tibial plateaus deepend?
The reason is because the flattened tibail pateaus are not a good fit for the femoral condyles .
By deepening them you are improving the fit
What sit he shape Meniscis?
2 C shaped wedges of fibrocartilage
What part of the menisci is thicker?
Thicker at the external margins
What are the functions of the menisci?
Increase joint congruency
Distribute weight evenly
Shock absorption
Assist in locking mechanism
What does the external edges of the menisci attach to?
Attach to the fibrous capsule of the joint
Which side of the meniscus is firmly attatched to a collateral ligament? State which collatearl ligament.
The medial meniscus is firmly attatched to the tibial (medial) collateral ligament
Is the lateral meniscus attatched to a collateral ligament?
Lateral meniscus is not attached to the lateral ligament on that side –> compeletly seperate
How is the mensical torn?
Due to sport injury or degenerative changes
What can happen during knee movement if you have a torn meniscal?
Displaced cartilage can become trapped during knee movements – pain or locking
What is the treatment of torn meniscal?
Repair or resection
What are all the different types of meniscal tear? 6 of them
Vertical Transverse Peripheral Bucet handle Parrot beak Flap
What is damage to meniscal tear associated with?
With the development Oesteoarthritis
Why is the prognosis of menisacl tear not good?
Poor blood supply to the area –> therefore poor capacity to recover
What are the intra articular ligments?
Anterior and posterior cruciate ligament –> sit between the tibia and fibia
What are the extra articular ligaments?
The fibular (Lateral) and tibial (medial) collateral ligaments –> go down each side of the joint
What structures stabalise the knee joint?
Surrounding muscles –> strength and integrity improves recovery speed
Intra articular ligaments –> ACL and PCL
Extra articular ligaments
FCL and TCL
What is another name for the fibular and tibial collateral ligaments?
Lateral and medial collateral ligaments respectively
What can possibly happen if you tear the medial meniscal?
High chance you will also tear the tibial collateral ligament –> due to being attatched together
Will the fibial collateral ligament tear if you tear the lateral meniscal?
No as they are not attached to each other
Where do the two crucial ligaments cross?
Cross each other obliquely in the centre of the knee
What is the proximal and distal attachment of the PCL?
The posterior cruciate ligament attaches to the posterior intercondylar region of the tibia and travels supero-anteriorly to insert onto the medial femoral condyle
What is the proximal and distal attachment of ACL?
The anterior cruciate ligament attaches to the anterior intercondylar region of the tibia and travels supero-posteriorly to attach to the lateral femoral condyle
What is weaker the PCL or ACL?
ACL
Where is the position of the cruciate ligaments?
Inside the joitn capsule but outside the synovial membrane
What is the function of the posterior crucial ligament?
Prevents posterior displacement of the tibia on the femur –> prevent tibia sliding backwards from the femur.
Prevents hyperflexion
Main stabiliser of the flexed knee when weight bearing e.g. walking down hill
How is the PCL damaged?
Can be damaged when landing on the tibial tuberosity with the knee flexed
What is the function of ACL?
Prevents anterior displacement of the tibia on the femur
Prevents hyperextension
How is the ACL damaged?
Occurs when knee is hyperextended or force is applied anteriorly
What is the tibial (medial) collateral ligament attach to and what is its function?
Flat band attached to the medial meniscal and prevents abduction of the leg at the knee
What is the febular (lateral) collateral ligament attach to and what is its function?
Cord like band NOT attached to lateral meniscus
Prevents adduction of the leg at the knee
What is the action of both the tibial and fibular collateral ligaments?
Both prevent rotation during extension of the knee contributing to stability while standing
What 3 structures are damagd in the combined knee injury? (unhappy triad)
The tibial collateral ligament tears and is attached to the
Medial meniscus so that tears too.
ACL also is torn
What causes the combined knee injury?
Caused by excessive lateral twisting of the flexed knee or blow to the lateral side of extended knee
Why does the ACL tear in combined knee injury?
It tears as it is taught in flexion
What is the common cause of combined knee injury?
When the knee is flexed and is twisted
What muscels are the main stabaliser of the knee?
Quadriceps Hamstrings (posterior thigh) Sartorius Gracilis Iliotibial tract
What is done to compensate for ligament damage and avoid surgery?
Do exercise and physiotherpay to buidl the quads which can compensate
What is the main two bursae? What are there positions?
Prepatellar bursitis infront of the paterlla
Suprapatellar bursa –> behind the patella
What type of fractures occur in the knee joint?
Fractures of the patella, tibia or distal femur
Can occur due to traumatic
Osteoporotic bone (i.e. low energy forces can cause fracture)
Peri-prosthetic –> occur near a knee replacement
Common cause of meniscal injury?
Acute injury/trauma
Wear and tear
What is common injury to the ligaments of the knee?
Tear and rupture caused by trauma
What are the different types of dislocation of the knee?
of the patella – more common in females
whole knee joint – very uncommon
Acute injury / traumatic
What is the direction of the patella as it is dislocated?
Nearly always altearlly due to the alignment of the knee
What prevents the patella during dislocation to move fully lateral?
The lateral femoral condyle
What are the bursae of the knee?
Fluid filled pouches around the knee
Why does the patella mostly dislocate laterally?
Due to the Rectus femoris, vastus intermedius and vastus lateralis all pulling superolaterally
What muscles tries to counteract the movemetn of the patella laterally?
The vastus medialis counteracts by more horizontal pull but this is sometimes overcome during dislocation
What is the direction of dislocation of patella associated with?
Related to the alignment of the femur in relation to the tibia
What is the purpose of having the knee positioned under the hip?
Returns centre of gravity to the midline and distributes weight evenly across the knee which is Achieved by obliquity (angle) of femur
What is the Q angle?
The angle between the femur on the tibia
What is the difference beteen structure of female and male pelvis?
The female pelvis is wider and more shallow
What is the consequence of the wider and more shallow female pelvis?
Therefore the angle of the neck of the femur is different to the one on the male –> the angle of femur on the tibia is larger than on men
Does female or males have greater Q angle and what can it cause?
Greater Q - angle in females as femur more oblique (due to wider pelvis)
Large Q-angle + strong quad contraction = dislocation
What happens if you disrupt the alignment of the knee and hips?
Get abnormal loading across the knee joint which can lead to arthritis
What occurs in Genu varum?
Also called bow leg Condition. Where there is disalignment of the tibia which is adducted with respect to the femur.
Leads to more weight bearing on medial tibial condyle - osteoarthritis in medial part of knee
Get wear, tear and pain
What occurs in Genu valgum?
Also called knock knee Conditions.
Where the disalignment of the tibia which is abducted with respect to the femur.
Leads to more weight bearing on the lateral tibial condyle - osteoarthritis in lateral part of knee
What is the cause of osteoarthritis?
Usually caused by wear and tear with age
What can increase the chance of a younger person getting osteoarthritis?
Can happen earlier if people have already had some sort of injury to the knee or if they are overweight ( extra pressure on joints) will get onest of arthritis earlier on.
Whata the 3 main changes that occur in developement of osteoarthritis?
Reduced joint space - little menisci or cartilage there, bone on bone which is very painful
Osteophyte formation - bone spur which form when the bone is damaged and tries to remodel itself but does so abnormally
Sclerosis of bone - abnormal density of bone also to do with remodelling and repair of damaged bone
Does the level of pain and symptoms always correlate to how osteoarthritis has developed?
No you can have little or not symptoms and be at a high grade of osteoarthritis and vice versa
What is Bipartite patella?
When the patella is composed of two parts
What can Bipartite patella be confused with?
Patellar fracture
What is torn in complete knee dislocation?
Complete displacement and tear of the cruciate ligament inside the joints and the collateral ligaments and even some of the muscle attachments and tendons or at least tear
What would you be worried about in complete knee discloation? How would you test for it?
You would be worried that the blood vessels and nerves around the knee joint are damaged.
Would look for the pulse in the foot and the temperature of the foot to see if the blood vessel in the knee had been occluded or not
How do you differentiate between bipartite patella and paterllar fracture?
Bipartite patellar would be in 2 smooth pieces, patellar fracture broken edges are jagged
What is the shape of the patella?
It is a traingular sesamoid bone that develops in the tendon of the quadriceps muscles.
It has a basee,apex and two surfaces ( articular and anterior)
Two facets –> lateral and medail
How does the vastus medialis prevent the patella being pulled to laterally?
The vastus medialis pulls at much more oblique angle than the other 3 quadricep muscles
what is the consequence if the body ridge on the lateral femoral condyle is udnerdeveloped?
It can lead to reccurent dislocatins of the patella
What is the consequence of a direct blow on the patella?
May split or shatter it but the fragments are not avulsed because the quadriceps expansion remians intact
Define alvusion?
Is an injury in which a body structure is forcibly detached from its normal point of insertion by either trauma or surgery
What movements are possible at the knee?
extension to 0 degress
Flexion –. 120 to hip extended, 140 hip is flexed, 160 passively
Lateral and medial rotation but need the knee to be flexed if not then rotation occurs at the hip joint.
