Week 1

Question 1

20 year old male presents with debilitating arthritis. He has a history of urine turning dark upon exposure to light. Further examination shows darkening of his pinna. The affected tissue of the outer ear is similar to the make up of which of the following?

1. Vessel basement membrane
2. Uterine elastic material
3. Nucleus pulposus of intervertebral discs
4. Tendons
5. Newly healing skin laceration

Answer 1

This patient has alkaptonuria, a genetic deficiency of homogentisate oxidase, leading to buildup of homogentisate which is an intermediate in the metabolism of tyrosine into acetoacetate. Homogentisate builds up in bone giving debilitating arthritis (usually lower back) and classically deposits in the visible cartilage like the pinna. Cartilage of the pinna is mainly made up of Type II collagen. Type II collage is also the main make-up of nucleus pulposus of the intervertebral discs (Choice C)

1. Vessel basement membrane is made up of Type IV collagen
2. Uterine elastic material and any elastic collagens are mainly Type III collagen
3. Correct answer
4. Tendons are mainly Type I collagen
5. Newly healing skin lacerations are full of granulation material which is mainly inflammatory cells and type III collagen (along with some newly forming vasculature)

Lecture: Cartilage Histology

Learning Objective: Describe the functions and locations of cartilage. (MKS1a)

Question 2

5 year old male presents with multiple limb and truncal bone fractures. With concern of child abuse, the medical team does a thorough physical exam. Examination shows deformed limbs from repeated broken bones and mild conductive hearing loss in the left ear. Furthermore, sclera seem darker than usual. Which of the following gives the best explanation of why the sclera are dark?

1. Vitamin A deficiency induced keratomalacia
2. Adenovirus causing conjunctivitis
3. Retinoblastoma
4. Ehlers-Danlos syndrome
5. Thinning of sclera

Answer 2

Answer: This patient has osteogenesis imperfecta (OI). OI stems from a decreased function of proper Type I collagen. Multiple genetic mutations have been associated with OI. OI can give pathogenic fractures, hearing loss (improper ossification of inner ear bones), and dark-blue colored sclera. This happens because of the thinning of the Type I collagen in the sclera with transparency enough to show dark blue colored choroidal veins

1. Vitamin A deficiency induced keratomalacia looks far worse than “dark sclera” and does not explain the other symptoms
2. Viral conjunctivitis presents with ocular erythema/injection and variable discharge and crusting
3. Retinoblastoma does not present like this
4. Ehlers-Danlos syndromes are a heterogeneous group of connective tissue disorders. However, this patient clearly has OI and only Type I collagen disturbances
5. Correct answer

Lecture: Bone histology

Learning Objective: Identify the embryological/developmental basis of bone defects such as spina bifida, osteogenesis imperfecta, dwarfism, and gigantism. (MKS1a)

Question 3

65 year old female with a 40 year history of poorly managed type II diabetes mellitus presents with multiple fractures. She also has a history of multiple toe amputations, coronary artery disease, congestive heart failure, and end-stage renal disease for which she has dialysis 3 days/week. Which of the following could explain her fractures?

1. Decreased erythropoietin production
2. Genetic gain of mutation of FGFR3
3. Genetic loss of mutation of Type I collagen
4. Increased ACE levels
5. Decrease in active 1α-hydroxylase

Answer 3

Answer: This patient has a long standing history of Type II DM and most of the sequellae stemming from poor management of it. End-stage renal failure (ESRD) means she probably has a GFR of less than 15cc/min. Renal failure means all modalities governed by the kidney are compromised including electrolyte balance, fluid balance, decreased EPO production giving anemia, and Vitamin D deficiency from decreased amount of 1α-hydroxylase (converts 25-hydroxyvitamin D to calcitriol, the biologically active Vitamin D) caused by proximal tubular cell-loss.

1. Decreased erythropoietin production – this probably is true but does not explain the fractures
2. Genetic gain of mutation of FGFR3 – this is the genetic basis of achondroplasia
3. Genetic loss of mutation of Type I collagen – this is the pathophysiology of osteogenesis imperfecta
4. Increased ACE levels – This is probably true from her upregulated RAAS. Also a useful test in diseases with granulomas with epitheloid histiocytes/giant cells. The giant cells also have 1α-hydroxylase and may give hypervitaminosis D and hypercalcemia. This is an occurrence in such diseases as sarcoidosis.
5. Decrease in active 1α-hydroxylase – correct answer

Lecture: Metabolic Disease

Learning Objectives: Explain the mechanism of enchondral bone formation and its importance in the pathogenesis of congenital, metabolic, and acquired diseases of bone. MKS1a. Explain the salient clinical, radiologic, and pathologic features of common non-neoplastic diseases of bone and the pathophysiologic mechanism causing the disorder. MKS1a

Question 4

70 year old male presents with sharp shooting pain down the right buttocks and down the outside of the leg. He says the pain first started acutely when bending over to pick up a piece of heavy luggage during travel. The pain is replicated when he sits for long period of time. Spinal imaging could show compression of which of the following nerve roots?

1. T12
2. L5
3. L1
4. L3

Answer 4

Answer: This patient’s history and presentation is very classic for sciatica—usually a compression/irritation of a lumbar nerve root. It is likely this patient has a L4-L5 disc herniation that has compressed the L5 nerve root. Choice B is the correct answer.

Lecture: Functional anatomy of the back

Learning Objective: Describe the anatomy and function of the intervertebral disc. MKS1a

Question 5

23 year old woman presents with neck pain after being rear-ended at a red-light. Which of the following structures are more likely to be affected in this patient?

1. Ligamentum flavum
2. Anterior longitudinal ligament
3. Posterior longitudinal ligament
4. Interspinal ligament
5. Supraspinous ligament

Answer 5

Answer: This patient has whiplash and the ligament that is most at risk is the anterior longitudinal ligament which is meant to prevent hyperextension of the neck (Choice B)

Below is a picture clearly outlining the anatomy of the spinal ligaments

1. Ligamentum flavum is present in the dorsal portion of the inside of the vertebral canal
2. Anterior longitudinal ligament is the correct response
3. Posterior longitudinal ligament is present on the ventral portion of the inside of the vertebral canal and prevents hyperflexion
4. And E. also are not affected in whiplash

Lecture: Functional anatomy of the back

Learning objective: Describe how the joints and ligaments of the vertebral column contribute to stability/movement of the vertebral column and protect the spinal cord and spinal nerves. Explain how disruptions in normal articulation can cause back pain and neuromuscular problems. MKS1a