MSK II-First Aid Flashcards
What clinical tests may be positive in people who receive a blow where the arrow is pointing on the planted leg?
The structures that are commonly subject to injury in a blow of this sort are the unhappy triad: the ACL (anterior drawer/Lachman’s tests), MCL (abnormal passive abduction of leg) and meniscus (lateral more common than medial, McNeemar’s test)
A 24 year old laboring woman tried to go without an epidural anesthetic but has decided labor has become too painful. It is too late to give her an epidural, but you can block a particular nerve for her. How would you find this nerve?
You could block the pudendal nerve by locating it near the ischial spine.
An ice skater tries her triple axle and fails, falling on an outstretch hand. She does not hear or feel anything break, but experiences sudden numbness along her thumb, index and middle fingers. What bone is likely causing these symptoms?
The lunate can dislocate and cause acute carpal tunnel syndrome.
A 28 year old female falls after tripping over a curb and hurts her hand. Upon examination she describes pain on palpation of the anatomical snuffbox. How quickly will she be able to heal from her injury?
The most likely injury here is a fracture to the scaphoid bone. This bone has a recurrent blood supply that gets broken off in a fracture and slows the healing process.
A 19 year old male presents with a humeral fracture after falling off his bicycle. Physical examination reveals inability to abduct his arm to 90 degrees. What nerve was likely affected by this fracture and what muscles are affected?
The axillary nerve, causing a motor deficit in the deltoid.
A 39 year old female presents after a car accident with a mid-shaft humeral fracture. Why might someone just waking up after a long night of drinking have similar symptoms as she does? Why do they have these symptoms?
Both can cause radial nerve palsy. This affects the “BEST extensors” - Brachioradialis, Extensors of wrist and fingers, supinator and triceps. Dennervation of these muscles results in wrist drop and loss in sensation over the dorsum of the hand and posterior arm.
A 44 year old male presents to the ED after getting in a gang fight. He says he was hit just above the elbow with a baseball bat. His x-ray is shown below. What motor tests could you do to assess if nerve damage has also occurred?
The median nerve is subject to injury in this case. You could test thumb abduction, extension and opposition. You could also test wrist flexion and flexion of the index and middle fingers. You should also test for sensory deficit in the distribution of the median nerve.
A 14 year old boy takes a spill at the skatepark and fractures his medial epicondyle. He complains of sensory deficit on the pinky and ring fingers. How do you expect his wrist to move when you ask him to flex it? What else could you test in assessment of nerve damage?
It will deviate radially because the ulnar nerve no longer flexes the flexor carpi ulnaris. You could have him abduct his fingers to assess dorsal interossei function.
A 31 year old female takes a spill while skiing and can’t get up. You see her in the ED laying like this and promptly relocate her hip. What motor tests should you do when assessing her for nerve injury?
She may have injured the superior or inferior gluteal nerve, which is vulnerable in a posterior hip dislocation. This will result in a positive Trendelenberg’s test (superior gluteal nerve injury), an inability to abduct the thigh (superior gluteal nerve injury) or rise from a seated position (inferior gluteal nerve injury).
While doing rounds in the ICU you see a patient who has been laying on his side for hours. He is now complaining of loss of sensation in the anterolateral leg and dorsal foot. What motor tests could you do to assess nerve compression consistent with the sensory deficits presented?
This sounds like common peroneal compression. You would have him dorsiflex and evert the foot. Also, when walking he would have foot drop or steppage gait.
A 23 year old female comes to the ED after a car crash with anterior dislocation of the tibia. After resolving all immediate problems, you decide to test for nerve damage. She has lost all sensation on the sole of her foot. What motor tests do you suspect will be deficient with this information?
This is consistent with a tibial nerve injury. The tibial nerve inverts and dorsiflexes the foot and flexes the toes. She will also not be able to stand on her tip toes.
A patient comes to see you who had two fractures in the last month. He is 58 years old and also complains that his hats don’t fit anymore. You note thicker bones on physical examination. Serum calcium, phosphorus and PTH levels are all normal. He does, however, have increased alkaline phosphatase activity. Why is this patient more prone to bone breaks? Why do you see these results in the blood tests? What neoplasm is this patient at risk for in the future?
He has Paget’s Disease. In this disease, osteoclasts chew up bone, followed by rampant osteoblast activity and deposition of woven bone. Woven bone is not as strong as lamellar bone and he is more prone to bone breaks. Blood tests are mostly normal because osteoclasts and osteoblasts are still using similar amounts of calcium and phosphorus. Osteoblast activity is increased and thus so does ALP. He is at increased risk for osteosarcoma.
A 60 year old female comes to see you concerned about osteoporosis because she has gone through menopause. She insists that you order a bone scan to check, so you do, and you confirm decreased bone density. When considering medications, you decide to give her two, each one affecting progenitor cells. What cells will these drugs act on?
Hematopoietic cells are the precursors to monocytes and osteoclasts, so these may be inhibited. Mesenchymal cells are the precursors to osteoblasts, so these may be induced.
A 46 year old female comes to see you complaining of severe finger pain after opening a jar at her house. You order an x-ray and find that she has a broken femoral head. You order labs and find her PTH levels to be abnormally high. Why would you want to decrease her PTH levels as opposed to eliminating them? What other findings would you expect to see in her bone?
Low levels of PTH actually stimulate osteoblast activity. You would also expect to find brown tumors because rampant osteoclast activity can cause hemorrhaging.
A 71 year old female comes to your clinic after a fall at her house. She suffers from a femoral neck fracture and a Colles’ fracture. Serum calcium and phosphate levels are in their normal range. Why is this woman most likely suffering from these fractures after a simple fall? What medications could you prescribe her?
She no longer has estrogen. Estrogen inhibits apoptosis of osteoblasts and induces apoptosis of osteoclasts. When it is gone, excess bone resorption occurs and puts her at risk for osteoporosis. You could prescribe her SERMs (estrogen specific for bone and nowhere else), bisphosphonates (bind bone and inactivate osteoclasts), dietary calcium and dietary vitamin D. Also, once the fractures have healed you should prescribe regular exercise to encourage healthy bone remodeling.
A 66 year old man is a new father and his child has achondroplasia. Why will this man’s son have a larger head compared to the rest of his body?
In achondroplasia, FGFR3 is constitutively activated and inhibits chondrocyte proliferation. This only affects endochondral ossification and thus longitudinal bone growth, not membranous bone growth which occurs in the skull.
A mother brings her 8 year old boy in to see you because he broke his pelvis. She also says that he has been irritable and suffered from multiple illnesses this year. His x-ray is shown below and physical exam reveals hepatosplenomegaly. What is the most curative form of treatment for this little boy?
Bone marrow transplant to replace defective monocytes and osteoclasts. He is suffering from osteopetrosis, which can be caused by defective carbonic anhydrase II in osteoclasts, leading to defective bone remodeling, loss of bone marrow and extra-medullary hematopoiesis.
An 8 year old child comes to the ER, appear malnourished with bowing bones as seen in the x-ray below. What is this child likely deficient in and how is this contributing to his symptoms?
This poor kid has Rickets (osteomalacia in adults). This is a result of vitamin D deficiency which results in a decrease in serum calcium. The parathyroid senses this and stimulates bone resorption. This results in an overall decrease in mineralization of osteoid and the bones bow outwards.
How do lab values compare between osteoporosis, osteopetrosis, osteomalacia/rickets, osteitis fibrous cystic and Paget’s disease? Values are serum Ca2+, PO4, ALP and PTH.
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A 9 year old female comes to see you complaining of early menses and a disabling fracture of the femur. Physical examination reveals skin marks seen below. What medicine would you prescribe this patient for her bone condition?
This patient has a form of polyostotic fibrous dysplasia called McCune-Albright syndrome. This is characterized by precocious puberty, cafe-au-lait spots and bone lesions from overactive osteoclasts that results in bone replacement with collagen by fibroblasts. You could prescribe bisphosphonates to help her condition.
A 30 year old male presents with knee pain. His radiograph and biopsy are shown below. What is your diagnosis? Prognosis?
Benign giant cell tumor. These often occur in the epiphyseal regions of long bones and have a soap bubble appearance on x-ray. They also demonstrate spindle-shaped cells with multinucleate giant cells on a biopsy.
A 23 year old male presents with an enlarging mass on the side of his knee over the past few months. The biopsy and radiograph are shown below. What is your diagnosis? Prognosis?
Benign osteochondroma. These tumore originate from long metaphysis and are encased by a cartilaginous cap as seen in his biopsy.
A 15 year old male comes to see you complaining of knee pain that has gone on for a few weeks after his hiking trip. His x-ray is shown below. How would you treat this kid?
He most likely has an osteosarcoma, which is the second most common malignant tumor in kids after rhabdomyosarcoma. Note Codmans triangle at the matphysis of the femur, indicating aggressive tumor growth through the bone cortex. I would treat the cancer aggressively as it could metastasize to the lungs.
An 11 year old boy comes to see you complaining of pain in his middle thigh, fatigue and recurrent infection. Biopsy of the lesion and x-ray are shown below. What is the pathophysiology of his condition?
Note the “onion-skin” tumor and the small blue malignant cells. This is Ewing sarcoma. Tumor cells are generated from a translocation t;(11,22).
A 45 year old male comes to see you complaining pain in his femoral region and a palpable bump. X-ray and biopsy are shown below. What is your diagnosis?
Malignant chrondrosarcoma.
A patient presents to the rheumatology clinic complaining of hand pain solely in the DIPs and PIPs. There is no swelling and pain subsides with rest. What do you expect to see on radiographs of this patient’s hands?
Involvement of these joints is typical in osteoarthritis. Thus, you would expect to see joint space narrowing, sclerosis, possible subchondral cysts, and bone spurs.
A patient presents to the rheumatology clinic complaining of symmetric hand pain in the MCPs and PIPs. The joints are stiff for about 2 hours in the morning, but improve with use. What other physical exam findings to expect to see in this patient?
This patient likely has rheumatoid arthritis due to MCP involvement, symmetry and morning stiffness. You could also see subcutaneous rheumatoid nodules, ulnar deviation of the fingers, boutonnieres, and swan neck deformities.
Analysis of a 34 year old female’s finger joints reveals erosions and osteopenia in the shafts of the metacarpal bones. What pathology could be causing these findings if you found out she was HLA-DR4 positive? How could you further test your hypothesis?
HLA-DR4 has a strong association with rheumatoid arthritis. The pathology occurs from immune-mediated pannus formation of the joint and thus erosion due to cytokine activation of osteoclasts. You could further test for rheumatoid factor (anti-IgG antibody) and anti-CCP antibody.
How would you prescribe differently to someone with OA vs. someone with RA?
They could both benefit from NSAIDs and glucocorticoids. However, the RA patients also benefit from immunosuppresants such as TNF-alpha inhibitors, methotrexate and sulfasalazine.
A 48 year old male presents with a red and painful big toe. He also has typhus formation on his left ear. History reveals that he was at his 20 year reunion and got hammered last night. What is causing the symptoms he presents with today? What do you send him home with?
He has an acute gout attack from alcohol consumption. Alcohol competes with the same excretion sites in the kidney as uric acid. This results in decreased excretion of uric acid and build up in blood. You could send him home with NSAIDs.
While working in a lab you get a sample and see this under the microscope. What do you see and what things can cause precipitation of this in joints?
These are monosodium urate crystals common in gout. Note needle shaped, yellow crystals under parallel light. Common causes include hyperuricemia from Lesch-Nyhan syndrome (HGPRT deficiency resulting in PRPP excess), decreased excretion of uric acid from thiazide diuretics, increased cellular turnover or von Gierke’s disease (increased pentose phosphate pathway production of ribose-5-P, and thus increased production of nucleotides and uric acid)
How do you treat chronic gout?
Xanthine oxidase inhibitors like allopurinol and febuxostat
A 50 year old male presents with swelling, redness and pain in his knee. Joint aspiration yields the image below. What does this patient have?
Pseudogout. Notice the blue crystals under parallel light. Calcium pyrophosphate crystals show up like this. They also tend to deposit in the knee because of their affinity for type 1 collagen, which is in the meniscus.
A 19 year old male presents with pain that started in his foot, went away and came back in his knee. He also says he has pain in his achilles tendon. You not pustules on the back of his hand. What organism is likely causing this arthritis?
Neisseria gonorrhoeae. “STD” = Synovitis (knee), Tenosynovitis (Hand) and Dermatitis (pustules)
A 79 year old female comes to see you with severe hip pain. Her history reveals corticosteroid use for the past 7 years because of an inflammatory joint condition. You get an x-ray of her hip, which is shown below. What is likely causing her condition?
Osteonecrosis due to long term steroid use and decreased blood flow to the femoral head. This condition can also be a result of alcoholism, trauma and sickle-cell disease.
A patient comes to see you with a chronic inflammatory arthritis. You test his blood and determine that he does not have RA. What conditions are now in your differential diagnosis?
Blood work likely showed absence of anti-IgG antibody (RA factor). Absence of this leads you to think of the seronegative spondyloarthropathies = “PAIR”. Psoriatic arthritis, Ankylosing spondylitis, IBS and Reactive arthritis.
A 27 year old patient comes to see you complaining of joint weakness in his left foot and right hand. Examination of his foot reveals the image seen below. He also has scaling rashes on his elbows. What may you find in his radiograph?
Pencil-in-cup deformity that happens in 1/3 of patients with Psoriatic arthritis.
A 29 year old male presents with low back and SI joint pain. He also has red eyes and a heart murmur. X-ray of his spine is shown below. What is your diagnosis?
Ankylosing Spondylitis. Note bamboo spine from ankylosis of vertebral joints.
A 30 year old female presents with inflamed and red left knee and right ankle joints. Blood labs show no RA factor. She states that she had a bout of diarrhea a few weeks ago after getting back from Mexico. What gene may have made her susceptible to this type of arthritis?
This is arthritis due to inflammatory bowel disease (enteropathic arthritis). It is a type of seronegative spondyloarthropathy. People who are HLA-B27 are more sensitive to seronegative spondyloarthropathies.
A 31 year old male comes to see you complaining of eye pain, pain with urination and joint pain in his left knee. Lab tests show that he is positive for chlamydia trachomatis. What is the most likely diagnosis for this patient?
Reactive arthritis (Reiter’s syndrome). “Can’t see, can’t pee, can’t climb a tree).
You are in medical school and have seen a significant decrease in physical activity so you go to a doctor and get your muscle cells checked out to see if they’re still alive. Which fibers are you likely to see a decrease in on the slide below?
The light ones. These are the type 2, fast-oxidative ones that go first due to inactivity.
A 15 year old male comes to see you complaining of progressive muscle weakness. He complains that he can’t even comb his hair anymore, with either hand. He also has GI symptoms and a rash. What cells are causing these symptoms and how would this condition present in an adult? What blood markers tip you off to this condition?
This is dermatomyositis. This condition is caused by CD4+ cell attack on perifascicular capillaries. In an adult, the disease may present with Grotton’s lesions and increased risk for cancer. Anti-jo-1 antibodies and ANA tip you off to this condition.
A patient comes to see you with an inflamed right MTP. He has a history of gout and you decide to give him a corticosteroid injection into his MTP. Where are the injected corticosteroids acting in the inflammatory pathway?
They inhibit phospholipase A2 release of arachadonic acid from phosphatidylinositol. They also inhibit NF-kB and thus protein synthesis of COX1 and COX2 enzymes.
A cardiac patient comes to see you after having a pulmonary embolism. He has recovered, but you advise him to take daily low dose Aspirin. Why do you prescribe low dose over high dose?
Low dose aspirin only inhibits COX-1 and thus decreases platelet aggregation while still allowing prostacyclins to induce vasodilation.
A 49 year old male presents to the ED after a long night of drinking. He says that he had a splitting headache at 3 o’clock in the morning and took a bunch of Tylenol for it. What enzymes do you think will be elevated in his labs? What could you give him to treat him?
AST and ALT levels will be high due to hepatic necrosis. You could reverse these symptoms by giving him N-acetylcysteine, a drug that regenerates the glutathione depleted by the toxic acetaminophen metabolite (NAPQI) that originally formed the toxic tissue in the liver.
Bisphosphonates (alendronate and other -dronates) are indicated for use in what diseases of the bone?
Those with rampant osteoclast activity. These work by binding hydroxyapatite in bone and inhibiting osteoclast activity. This includes osteoporosis, hypercalcemia, and Paget’s disease of the bone.
Where do these drugs act in long term treatment of gout: allopurinol, febuxostat, probenecid and colchicine?
They act at xanthine oxidase, the proximal convoluted tubule of the kidney and at leukocyte mediated inflammation.
A 39 year old patient comes to see you complaining of a painful swelling in her left knee that has been going on intermittently for the last three years. She has also recently had some heart issues that are being resolved by the cardiologist along with numbness in her face. What organism has likely caused her symptoms?
Everything but the targetoid rash in this case is typical of Lyme’s disease caused by the Borrelia burgdorferi bacteria transmitted to us via ticks. Infection causes pannus formation and bone destruction in the joint.
This patient presents to the clinic to figure out why she had such a hard time stopping bleeding when she got her appendix out. A defect in what two enzymes could cause this condition?
Carboxy or amino tropocollagen peptidases. This results in a type of Ehlers-Danlos. It can also happen when lysyl oxidase is mutated and collagen can no longer form cross-links with other fibers.
What vitamin is deficient when the process shown at #1 is not functioning properly?
Ascorbic acid (Vitamin C). This is deficient in scurvy, which is a decrease in hydroxylation of proline and lysine residues due to loss of integrity of prolyl hydroxylase enzyme. This happens because ascorbic acid is no longer present to reduce Fe3+ back to Fe2+.
What is Gowers’ maneuver a sign of? How would you test to make sure?
It is a sign of pelvic girdle weakness that first develops in kids with muscular dystrophy. Muscular dystrophies are X-linked disorders. You would test to make sure by looking for increased CK levels and a muscle biopsy similar to that seen below.
Which of the images below are indicative of Becker’s Muscular Dystrophy?
The middle one. It is a result of a mutated dystrophin gene. It is not as severe as Duschenne’s because it is at least still present.
An 8 year old boy comes to your clinic complaining of fatigue throughout the entire day. You order blood tests and the results are seen below. What enzyme deficiency might this boy be suffering from?
Glucose-6-Phosphate Dehydrogenase Deficiency. This results in HMP shunt defect, decrease in NADPH production and inability of RBCs to reduce glutathione. This results in Heinz bodies, which is denatured hemoglobin, and eventually hemolysis.
A 9 year old female comes to see you because she feels lightheaded and has been vomiting whenever she has fruits. What marker would you test for in her blood if you think her condition has to do with what she is eating? What do you prescribe?
It is likely that this patient has HFI (hereditary fructose intolerance). This is a defect in aldolase B, that causes a backup of fructose-1-phosphate, which you would test for in her blood. This back up turns down glycogen phosphorylase and thus decreases available ATP and Pi in the body. You would prescribe not eating fructose or sucrose-containing foods.
How do sperm pack their lunches?
Polyol pathway. Glucose => Fructose.
How does your body utilize the different metabolic pathways from a freshly fed state to a withering fasting state?
Fed = glycolysis and storage. Between meals = Glycogen usage. 1-3 days starvation = Fat, gluconeogenesis and glycogen After day 3 = fat, ketone bodies and protein.
