Cartilage, Bone, Metabolic, and Vertebral Disorders

Flashcards covering bone and cartilage diseases, hormonal and vitamin disorders of bone formation, calcium and phosphate homeostasis, spinal curvatures, neural tube defects, and cervical spine fractures.

What biochemical matrix alteration and clinical symptoms characterize Osteoporosis in the cartilage/bone disease table?

A decrease in proteoglycan leading to a reduction in intercellular water in the cartilage matrix; symptoms include progressive reduction of mobility and increased pain with joint movement (affecting hips, knees, and vertebrae).

How are Primary Type 1, Primary Type 2, and Secondary Osteoporosis distinguished by etiology?

Primary Type 1 occurs in postmenopausal women due to decreased estrogen levels increasing osteoclast activity; Primary Type 2 occurs in the elderly; Secondary osteoporosis develops due to drug therapy or other diseases.

What endocrine imbalance causes Gigantism versus Dwarfism, and what are potential complications of Gigantism?

Excess pituitary growth hormone causes gigantism, while lack of growth hormone ($\text{GH}$) causes dwarfism; gigantism may result in Acromegaly or a Pituitary Tumor.

What are the skeletal effects of Vitamin A deficiency and excess Vitamin A?

Vitamin A deficiency inhibits proper bone formation and growth, whereas excess Vitamin A increases osteoclast activity.

What enzyme deficiencies cause Vitamin C Deficiency ("Scurvy"), and what are its symptoms?

Deficiency of prolyl hydroxylase (causing instability and no alpha chains of collagen) and lysyl hydroxylase (causing less O-glycosylation); symptoms include bleeding gums, hemorrhage, and poor wound healing.

What are the clinical signs of Vitamin D Deficiency, and how is it classified in children versus adults?

Soft pliable bones, bow-leg deformity, pigeon chest, frontal bossing, and rachitic rosary; it is termed Rickets in children and Osteomalacia in adults.

What laboratory findings are characteristic of Vitamin D Deficiency?

Hypocalcemia, hypophosphatemia, and increased alkaline phosphatase.

What causes Vitamin D Resistant rickets, and what distinct symptom accompanies it?

A mutation in the gene encoding the Vitamin D receptor in the intestine (decreasing calcium absorption); symptoms are identical to Vitamin D deficiency but with the addition of alopecia (hair loss).

What laboratory profiles differentiate Vitamin D Resistant rickets from Hypervitaminosis D?

Vitamin D Resistant rickets shows hypocalcemia, hypophosphatemia, and increased plasma $1,25(\text{OH})_2\text{D}$; Hypervitaminosis D shows hypercalcemia and increased plasma $1,25(\text{OH})_2\text{D}$.

What is the pathophysiology and soft tissue presentation of Hypervitaminosis D?

Vitamin D toxicity leads to enhanced calcium absorption and bone resorption, causing soft tissue calcification in the kidneys and arteries; symptoms include loss of appetite, nausea, thirst, and stupor.

What clinical manifestations and emergency treatments are associated with Hypocalcemia?

Symptoms include tetany, convulsions, cardiac arrythmias, stridor (glottis), and spasm of laryngeal muscles causing difficulty breathing; emergencies are treated with Calcium gluconate IV.

What are the primary causes of low versus high PTH levels in Hypocalcemia?

Low PTH levels occur in parathyroidectomy (hungry bone syndrome); high PTH levels occur from Vitamin D deficiency, PTH resistance, or drugs.

What are the classic symptoms and diagnostic methods for Hypercalcemia?

Non-specific symptoms described as "bones, moans, stones, and abdominal groans"; diagnosed with PTH immunometric assays combined with blood calcium measurements.

How do serum phosphate levels differ between Hypercalcemia caused by Hypervitaminosis versus excessive PTH?

Hypervitaminosis increases both calcium and phosphate (along with $1,25(\text{OH})_2\text{D}$), whereas excessive PTH increases calcium but decreases phosphate.

What is the symptomatic progression sequence caused by Hypercalcemia?

Impaired cognition $\rightarrow$ peptic ulceration $\rightarrow$ renal calculi $\rightarrow$ polyuria & polydipsia.

What causes Hypophosphatemia, and what monitoring protocol is required during treatment?

Caused by inadequate intestinal phosphate absorption (due to Vitamin D deficiency) or excessive renal phosphate excretion (due to PTH excess); levels of phosphate and calcium must be monitored closely every $6\text{--}12\,\text{hours}$ throughout treatment.

What laboratory threshold, causes, and symptoms define Hyperphosphatemia?

Serum phosphate level $>1.8\,\text{m/mol}$; caused by kidney impairment (decreased renal excretion) or hypoparathyroidism (excessive release of phosphate into ECF); manifests with calcification of soft tissue & organs, tetany, and seizures.

What is Kyphosis, and what is its severely sharply angled form termed?

An abnormal increase in thoracic curvature resulting in a hunchback; its severely sharply angled form is called a Gibbus deformity.

What anatomical biomechanics cause Lordosis?

The upper sacrum is flexed with an increased extension of the lumbar spine, causing anterior tilting of the pelvis ("pregnant lady posture").

What is Scoliosis, and what is a congenital cause of it?

Abnormal lateral curvature and rotation of the vertebrae; congenitally caused by hemi-vertebrae.

What is a Chordoma, what tissue does it arise from, and where is it typically located?

A slow-growing, malignant tumor formed from remnants of the notochord (which normally becomes the nucleus pulposus) that may infiltrate bone; typically found in the base of the skull or lumbosacral region.

What are the clinical presentation and physical findings of Spina Bifida Occulta?

An unfused vertebral arch with no bulge over the bony defect and no neurological deficits; skin is normal except for a tuft of hair or a skin dimple on the area.

How do Spina Bifida meningocele and Spina Bifida meningomyelocele differ in anatomical content and neurological outcome?

Meningocele contains only meninges and CSF in the subarachnoid space (spinal cord remains in normal position) with no neurological deficits; Meningomyelocele contains meninges, spinal cord, nerves, and CSF (displaced spinal cord) and causes severe neurological deficits such as paralysis, sensory loss, and bladder dysfunction.

What anatomical failure and presentation characterize Spina Bifida myeloschisis?

Failure of neural fold closure resulting in an open spinal cord (mass of neural tissue fully exposed with no dural or meningeal covering); it is the most severe form, causing partial or complete paralysis, bladder dysfunction, and increased risk of infection.

What developmental defect causes Meroencephaly/Anencephaly, and what factors are implicated?

Failure of the rostral neuropore to close, leading to the absence of a large part of the brain and skull (lethal); exact cause is unknown, but implicated factors include environmental toxins and lack of folic acid.

How are Type I, Type II, and Type III Odontoid Fractures distinguished by location and stability?

Type I is stable (fracture of upper dens, still attached to the apical ligament); Type II is unstable and most common (fracture at the base of the dens with a tear of the transverse ligament); Type III is stable with a high prognosis (fracture in the lateral masses of $\text{C2}$ below the dens).

What severe neurological consequence can occur from a posterior shift in an Odontoid Fracture?

A posterior shift of the fractured dens hits the spinal cord at $\text{C2}$, resulting in quadriplegia.