Joints of Lower Limb Flashcards
angle of Wiberg
angle b/w vertical and the plane of the acetabular rim - decreases may indicate joint instability
what can cause fractures of femoral neck?
- high energy impacts when lower limb is extended and force of impact is transmitted to hip joint
- osteoporosis in older people, mostly women
what do fractures of femoral neck cause?
- lateral rotation of the lower limb
- disrupted blood supply to head of femur -> aseptic vascular necrosis
osteoarthritis of hip joint
pain, edema, limitation of motion, erosion of articular cartilage -> causes disability
surgical hip replacement
- metal shaft into the femur w/ bone cement to replace femoral head
- plastic socket to replace acetabulum
what can separation of the superior femoral epiphysis cause in children?
post-traumatic avascular necrosis of femoral head
congenital dislocation of hip joint
inability to abduct thigh when femoral head is not properly located in acetabulum - affected limb appears shorter
-positive Trendelenburg sign
acquired dislocation of hip joint
uncommon b/c articulation is strong/stable
most common dislocation of hip joint
posterior dislocation - femoral head forced out of acetabulum, joint capsule ruptures inferiorly and posteriorly - causes shortening and medial rotation of limb
what nerve may be injured in posterior dislocation of hip joint?
sciatic nerve
what causes anterior dislocation of hip joint?
violent injury that forces the hip into extension, abduction, and lateral rotation - moves femoral head inferior to acetabulum and can cause fracture of acetabular margin
Q angle
angle b/w tibia and femur
which sex usually has larger Q angle?
adult females - b/c wider pelves
what does it mean to be bowlegged?
genu varum - decreased Q angle that causes weight-bearing line to fall medial to center of knee
-excess stress on medial meniscus
what does it mean to be knock-kneed?
genu valgum - increased Q angle that causes weight-bearing line to fall lateral to center of knee
-excess stress on lateral meniscus
what direction does the patella almost always dislocate?
laterally
what can cause abnormal tracking of the patella and chronic patellar pain?
imbalance of the lateral pull on the patella and the mechanisms resisting it
patellofemoral syndrome
pain from repetitive microtrauma from abnormal tracking of the patella relative to the patellar surface of the femur
most common knee injury in contact sports
ligament sprain
what does a TCL tear often also result in?
tear of medial meniscus - b/c of firm attachment of TCL to this meniscus
unhappy triad
tear of ACL, TCL, medial meniscus
anterior drawer sign
free tibia slides anteriorly under the fixed femur - seen in ACL tear - tested by Lachman test
what do PCL tears usually occur in conjunction with?
TCL or FCL tears
posterior drawer sign
free tibia to slide posteriorly under the fixed femur - seen in PCL tears
which meniscus usually tears?
medial
pain in medial and lateral meniscus tears?
medial: pain on medial rotation of the tibia
lateral: pain on lateral rotation of the tibia
why are some meniscus tears left to heal and some surgically repaired or removed?
only the periphery of meniscus has good enough blood supply to heal on its own
arthroscopy of knee
endoscopic examination of the interior of the knee joint
debridement
excision of devitalized articular cartilaginous material
joint effusions
escape of fluid from blood or lymphatic vessels- causing increased fluid into joint cavity
how is the needle inserted for aspiration of a knee joint?
Pt sitting on table w/ knee flexed - use three bony points for landmarks:
- anterolateral tibial (Gerdy) tubercle
- lateral epicondyle of the femur
- apex of the patella
what causes prepatellar bursitis?
friction b/w the skin and patella
housemaid’s knee
chronic prepatellar bursitis that causes bursa to become distended w/ fluid and form a swelling anterior to knee
what causes subcutaneous infrapatellar bursitis?
excessive friction b/w the skin and the tibial tuberosity
clergyman’s knee
edema over the proximal end of the tibia from subcutaneous infrapatellar bursitis
swelling in deep infrapatellar bursitis
b/w the patellar ligament and the tibia, superior to tibial tuberosity
suprapatellar bursitis
an infection caused by bacteria entering the suprapatellar bursa from torn skin
Baker cysts
popliteal cysts - abnormal fluid-filled sacs of synovial membrane in the region of the popliteal fossa
-almost always a complication of chronic knee joint effusion
total knee replacement arthroplasty
insertion of an artificial knee joint in people w/ diseased knees
what is the most frequently injured major joint in the body?
ankle
most common ankle injuries?
ankle sprains - torn fibers of ligaments caused by inversion injuries
what are lateral ligament sprains more common than medial ligament sprains?
lateral ligament is weaker than the medial ligament and is the ligament that resists inversion of the talocrural joint
which ligament is most vulnerable and most commonly torn during ankle sprains?
anterior talofibular ligament (part of lateral ligament) -> instability of ankle joint
what do shearing injuries fracture?
the lateral malleolus at or superior to the ankle joint
what do avulsion fractures break?
malleolus inferior to the ankle joint - fragment of bone is pulled off by the attached ligaments
Pott fracture-dislocation of the ankle
when foot is forcibly everted
- torn posterior tibiofibular ligament
- fractures fibula
- fractured medial malleolus
tarsal tunnel syndrome
entrapment and compression of the tibial nerve by the flexor retinaculum -> heel pain
hallux valgus
lateral deviation of the big toe caused by pressure from footwear and degenerative joint disease
-causes bunion and hard corns (inflamed areas of thick skin)
hammer toe
- proximal phalanx is permanently and markedly dorsiflexed (hyperextended) at the MP joint
- middle phalanx is strongly plantarflexed at prox IP joint
claw toes
hyperetension of the MP joints and flexion of the distal IP joints involving lateral 4 toes
types of pes planus
flexible flatfeet: flat, lacking a medial arch when weight-bearing but normal w/o weight (more common)
rigid flatfeet: flat even when not bearing weight
cause of flexible flatfeet
loose or degenerated intrinsic ligaments (inadequate passive arch support)
cause of rigid flatfeet
from a bone deformity, such as fusion of adjacent tarsal bones
acquired flatfeet
fallen arches - likely secondary to dysfunction of tibialis posterior (dynamic arch support) from trauma, degeneration
clubfoot
foot that is twisted out of position - all congenital
common type of clubfoot
talipes equinovarus - involves the subtalar joint
- foot inverted
- ankle plantarflexed
- forefoot is adducted (abnormally turned toward midline)
