SNUA 030 test 2

osteomalacia, osteoporosis, muscular dystrophy, compartment syndrome, hip replacement

Osteomalacia

The inadequate mineralization of bone tissue due to the deficiency of various vitamins and minerals (Vitamin D, calcium and phosphate)
The common name is soft bone disease
Rickets is similar but in children if the epiphyseal gap has not yet closed

Pathophysiology of osteomalacia

• Etiology: Disruption of Vitamin D pathway (either by inadequate Vitamin D intake, inadequate UV exposure, impaired hepatic and renal activation) results in active Vitamin D deficiency

• The decrease in active vitamin D leads to the decrease calcium and phospahte absorption in the gut (hypocalcemia, hypophosphatemia)

• Secondaty hyperthyroidism results because the low serum calcium causes the increase release of PTH because the body ties to increase the calcium levels. The PTH causes calcium to be leached from the bones, and increase phosphate excretion from the kidneys. This further worstenes the mineral deficit

• The lack of available minerals causes defective mineralization of the ostiod matrix

• The structual pathology: the defective minerilzation results in accumilation of thick layers of unminerilized osteoid (manifesting as weak, pliable bones)

• The serum ALP is elevated due to osteoblastic hyperactivity as the body attempts to strengthen the bone.

Causes of osteomalacia

• Primary cause: defective bone mineralization (in adults)

• Primary drivers

  • Vitamin D (essential for calcium absorption and maintaining bone health)

  • Calcium

  • Phosphate
    

Signs and symptoms of osteomalacia

• Pain in the bones/ joints

• Muscle pain and weakness (after exercise)

• Bones that break easily (hips/ lower back/ feet)

• Difficulty walking/ change in gait (waddle)

• Muscle cramps

• Parasthesia (pins and needles) in hands and feet often due to low Calcium levels

Predisposing factors of osteomalacia

(some risk factors disrupt the body's ability to maintain adequate Vitamin D, Calcium and Phosphate levels)

• Inadequate sunlight levels (sunlight is needed for Vitamin D pathway in liver/ kidney/ skin to form active Vitamin D) or people with limited sun exposure

• Poor intestinal absorption (in conditions like Crohn's disease/ Celiac disease/ diarhhea, Vitamin D and Calcium gets flushed out before it gets the chance to be absorbed)

• Impaired organ metabolism (the liver and kidneys are failing to activate Vitamin D and the kidneys are failing to prevent the loss of phosphate)

• Increased utilization (in pregnancy and breastfeedling, Vitamin D and calcium are used for breastmilk and the grwoing fetus)

• Increased loss (like gastrointestinal loss, in the case of diarrhoea Vitamin D and calcium is lost before being absorbed, in renal loss or kidney disorders Calcium and phosphate can be lost)

• People with darker skin colour, struggle with making Vitamin D

• Older adults

• Obese individuals

Osteoporosis

the condition that affects bone density causing weak brittle bone and can cause fractures (hip, spine, wrist)
Known as a silent disease because there are no obvious signs until a fracture occursP

Pathophysiology of osteoporosis

In normal physiology: bone remodeling is a continious process of bone resorption (breakdown done by osteoclasts) and bone formation (by osteoblasts). Osteoblasts and osteoclast work together to maintain bone health.

In osteoporosis bone resorption exceeds bone formation leading to a net loss of bone tissue.
Osteoclasts become overactive and breaks more bone down than necessary
Osteoblasts are un-able to keep up with the rate of bone resorption, leading to inadequate bone formation.
This will lead to reduced bone density, weakened bone stucture and the increase risks of fractures.

Clinical maifestations of osteoporosis

1. Early stages
   - no noticable symptoms
   - gradual loss of bone density

2. Progressive stage
   - Loss of height (compressed spine)
   - Back pain / stiffness
   - Kryptosis (stooped posture)
   - Brittle nails
   - Weak grip strength
   - Bleeding gums
   - Loose teeth
   - Fractures (hip, spine , wrist and others)

Cuases and risk factors of osteoporosis

• Aging (natural reduction of bone density)

• Genetics (family history and genetic predisposition play a role)

• Hormonal changes (the decrease of sex hormones (estrogen and testosterone) during meopaus and andropause)

• Nutritional deficiencies (inadequate Calcium, Vitamin D, magnesium and other essential nutrients)

• Medical conditions (hyperthyroidism, Rheumatoid arthrits, diabetes, gastational diabetes)

• Medications (long term corticosteroid use, anti-convulsants, chemotherapy, long term proton pump inhibitor use)

• Lifestyle factors (smoking, excessive alcohol consumption, poor posture, excessive caffeine use)

• Lack of excersie (sedetary lifestyle/ inadequate weight bearing activities)

Muscular dystrophy

Muscular dystrophy is a group of diseases that causes progressive weakness and loss of muscle mass. In muscular dystrophy abnormal genes (mutations) interfere with the production of proteins needed to form heathy muscles.

Duchenne MD

Mostly in children (males), rapidly progresses leading to wheelchair use (by 12 years old)

Becker MD

Like Duchenne MD but progresses slower and is diagnosed in early adulthood and adolescence

Myotonic MD

common as adult onset. Characterised by myotonia (inability to relax muscles after voluntary contraction) and can affect organs like the heart

Fascioscapular humeral MD

Affects muscles in the face, shoulder blades and upper arms

Limb- Girdle MD

starts in childhood and young adulthood which affects hip and shoulder muscles

Congential muscular dystrophy

present at birth until 2 years of age

Oculopharyngeal MD

appears in adulthood (age 40-70) and effects muscles of the eyelids and throat

Emery- Dreifuss MD

early contractures/ tightening of muscles of shoulders, upper arms and calf muscles

Distal musclular dystrophy (DD)

primary impacts muscles in hands, forearms and lower limbs