orthopedic pathology (muscle pathologies) Flashcards
atrophy
decrease in size (cells/muscle)
hypertrophy
increase in size (cells/muscle)
hyperplasia
Increase in number of muscle fibers
Does not occur under normal conditions
contracture
A contracture is the shortening of tissues surrounding a joint, leading to decreased range of motion
includes muscles, but also other tissues such as tendons or ligaments
contractures causes
burns, scars, disuse, many pathologies (cerebral palsy, muscular dystrophy, etc)
Ischemic Necrosis
Some texts say muscles will undergo necrosis after 6 hours
(some texts say 3 hours)
muscular dystrophy
largest and most common group of inherited progressive neuromuscular disorders
how many types MD
more than 30 genetic diseases
MD characterized by
progressive weakness and degeneration of skeletal muscles
Most common form of MD
Most severe form of MD
Duchenne’s MD
differ in types of
type of inheritance, area affected, age at onset, and rate of progression/prognosis
Duchenne’s MD rate
1/3500 male births
Duchenne’s MD – lack in which muscle protein
dystrophin
dystrophin function
Protein that helps muscle fibers maintain their shape/strength
“helps link thin filaments to the sarcolemma for stability”
Duchenne’s MD etiology
Etiology - Genetic (x-linked recessive)
x linked recessive inheritance
X-linked recessive inheritance refers to genetic conditions associated with mutations in genes on the X chromosome.
A male carrying such a mutation will be affected, because he carries only one X chromosome.
A female carrying a mutation in one gene, with a normal gene on the other X chromosome, is generally unaffected.
when symptoms appear?
at 2 - 4 years of age
when loss of unassistec ambulation
Loss of ambulation occurs between 7 – 13 years of age
respirator?
“Night ventilation by body respirators for patients in chronic respiratory failure due to late stage Duchenne muscular dystrophy”
Duchenne’s MD respiratory system
eventually resulting in loss of ambulation, loss of respiratory muscle strength, and death from respiratory insufficiency.
The majority of patients develop cardiomyopathy.
Duchenne’s MD life expectancy
Life expectancy is 20 – 30 years of age
Usually die due to cardiopulmonary issues
Duchenne’s MD initially affects (which part of body)
Initially affects the girdles (shoulders and hips)
SSx
Muscle weakness
Lack of coordination
Spastic movements
Weight loss
Contractures, loss of ROM, deformities – painful
where is there pseudohypertrophy in Duchenne’s MD?
calves
fat storage, not muscle (?)
Gowers’s sign
The sign describes a patient that has to use their hands and arms to “walk” up their own body from a squatting position due to lack of hip and thigh muscle strength
Duchenne’s MD Gower’s sign
Difficulty getting up from seated or lying position
walking, respiratory muscles
Waddling gait
Respiratory muscle failure
mental disability (?)
not always, but very common
dystrophin role in brain
Duchenne causes abnormal expression of dystrophin in the brain.
The function of dystrophin in the brain is not as well understood,
but recent studies have shown individuals with Duchenne to be more prone to ADHD, learning difficulties, anxiety, and autism spectrum disorder (ASD).
Duchenne’s MD posture
APT (weak abdominal muscles, weak hamstrings/glutes)
—> distended belly (weak abdominal muscles)
hyperextended knees to bear weight (due to weak quads)
—> Thin weak anterior thigh
tight calcaneal tendon (walking on toes)
weak muscles of dorsiflexion (footdrop)
poor balance, falling often
Less common and less severe than Duchenne’s MD
Becker’s MD
Becker’s MD rate
1/ 20,000 males
dystrophin levels in Becker’s vs Duchenne’s
Duchenne’s almost none
(Becker’s) Dystrophin levels are higher than in Duchenne’s MD
Becker’s vs Duchenne’s symptoms
Symptoms are same as Duchenne’s,
except occur later in life and progress more slowly
Becker’s when do signs/symptoms appear?
late childhood
diagnosed between 5 – 10 years of age
when is muscle weakness apparent?
Muscle weakness not significant until midlife
when is ambulation affected?
Can walk into teens/early adulthood
Loss of ambulation by late 20’s
Becker’s life expectancy
Lifespan into 40’s or 50’s
MD diagnosis – blood test
blood test (creatine kinase test?)
MD diagnosis (EMG)
Electromyography (EMG)
(firing pattern)
MD diagnosis – ultrasound
ultrasound (“Quality of muscle tissue”)
MD diagnosis – biopsy
muscle biopsy (Looking for dystrophin)
MD diagnosis – genetic testing
Genetic testing (Detecting presence of mutated gene)
creatine kinase test
This test measures the amount of an enzyme called creatine kinase (CK) in your blood.
CK is a type of protein. The muscle cells in your body need CK to function.
Levels of CK can rise after a heart attack, skeletal muscle injury, or strenuous exercise.
MD treatment
No cure. Treatment is aimed at increasing physical ability, allowing for a better quality of life.
alleviate symptoms, improve quality of life
