MST Week 5 (osteoarthritis And Rheumatoid Arthritis) Flashcards
(47 cards)
What are synovial joints
All the joints of the lower limb (hip, knee and ankle) are synovial joints
The 2 articulating bones are separated by a joint cavity
Bearing surfaces have an articulate cartilage converting
They are richly innervated
Each has an anastomosis (blood supply)
Describe the hip joint
Strong and stable joint (ball and socket is deep)
Ball and socket synovial joint
Wide range of movements
Possible movements in the hip joint
Flexion / extension
Abduction / adduction
Inward / outward rotation
Describe the functions of the different ligaments of the hip
Illiofemoral ligament - prevents hyperextension. Strong
Pubofemoral ligament - prevents excessive abduction
Ischiofemoral ligament - weak
Work together to keep the femoral head in acetabulum (reinforced by muscles)
How does shentons line help diagnose fractures of the hip
It should be a curved, continuous smooth line on a scan so if its not, that is a good indicator
Action of hamstrings on posterior compartment of thigh
3 muscles: biceps femoris, semitendinous, semimembranosus
Extension of hip and flexion of knee
So cross hip joint ( attach to ischial tuberosity)
Innervated by sciatic nerve
Damage to superior gluteal nerve
Normally the gluteus medius and minimus contract to keep pelvis level when contralateral foot is off floor
When damaged, the gluteus medius and minimus do not contract to keep pelvis level
Describe the knee joint
Quite strong and stable
Hinge synovial joint
Primarily flexion and extension
Limited rotation
In full extension and foot on ground the knee is ‘locked’ due to some medial rotation - forms a strong column for weight bearing
Function of knee ligaments
Anterior cruciate ligament - limits posterior rolling of femur on tibia and hyper extension
Posterior cruciate ligament- limits anterior rolling of femur on tibia and hyper extension
How can you test the collateral ligaments
1) take leg in the hands with knee straight
2) gently abduct the knee to test fibular collateral
3) gently adduct the knee to test tibial collateral
4) there should be little movement
How do you test the cruciate ligaments
1) patient lies with knee flex at 90 degrees
2) sit on the foot of the leg to be tested
3) pull the leg forward from the tibia this test the anterior cruciate
4) push the leg back this tests the posterior cruciate
5) it is called the drawer test
6) there should be little movement
Function of the menisci
Important in shock absorption
Medial meniscus is less mobile than the lateral meniscus
How do you unlock the knee
In full extension and foot on the ground the knee is ‘locked’ due to some medial rotation of femur on the tibia
Many muscles can relax in this position
To ‘unlock’ the knee- popliteus contracts to laterally rotate the femur on the tibia by 5 degrees
What is bursitis
Many bursae around the knee
Can get inflamed
Become distended and form a painful swelling
Can also form cysts in the popliteal region = bakers cysts
Maybe from bursa, can also be sacs from synovial membrane
Describe the ankle joint
Stronger and more stable during dorsiflexion
Relatively unstable during plantarflexion
Hinge type synovial joint
Tibia / fibula forms a mortise into which body of talus fits
Function of the ankle joint
Allows dorsiflexion and plantarflexion with small amounts of other movements allowed in plantarflexion due to instability eg Evers ion and inversion
Describe ankle sprains
Anterior talofibular ligament: the one most likely to be damaged in an ankle sprain, can be partially or fully torn
The calcaenofibular ligament may also be torn
Dislocation of the ankle joint
Called a pott fracture
Due to foot being forcibly exerted
Medial ligaments strong- can fracture medial malleolus
Talus moves in a lateral direction- fracturing lateral malleolus or fibula
What are the 7 tarsal bones of the foot
Talus Calcaenus Navicular Cuboid 3 cuneiforms: medial, intermediate, lateral
What is hilton law
The nerve supplying the muscles that cross over and act on a joint, also innervate that joint
Benefits and drawbacks of X-rays
Quick and inexpensive
Usually detect most fractures
Low radiation dose
Dependent on skill of doctor
Overlapping structures can cause subtle injuries to be missed
Poor examination for soft tissue pathology
Benefits of CT scans
Relatively quick for scanning large areas of the body and readily available
Provides good anatomical information in multiple planes
Greater sensitivity for detection of fractures
Cons of CT scans
Larger doses of radiation compared to X-ray
Prone to metal artefact which obscures images
Contrast resolution is relatively poor for soft tissues
Benefits of MRI
Excellent anatomical detail of soft tissues
Multiple planes and sequences allows detection of subtle abnormalities
Radiation sparing investigation
