Anatomy Clinical Correlations

Question 1

What is achondroplasia?

Answer 1

Achondroplasia

• A very common (1 in 15 000-40 000 live births) form of dwarfism, characterized by short upper and lower limbs in association with an average-sized trunk
• Caused by mutations in FGFR3
• 80% of cases caused by spontaneous mutations
• Autosomal dominant inheritance
• Mutation inhibits cartilage growth at growth plates of long bones, resulting in shortened limbs

Question 2

What is syndactyly?

Answer 2

Syndactyly

• Webbing between digist is among the most common birth defects
  
  • Cutaneous syndactyly: interdigital webs do not degenerate
  • Osseous syndactyly: digital rays do not separate

Question 3

What is the clinical period for limb development? What are some teratogens that are dangerous during this time?

Answer 3

Teratogens

• Teartogens acting during key windows of development can cause severe developmental anomalies
• The critical period for limb development is 24-26 days post fertilization
  
  • Thalidomide: used as an anti-nausea agent 1957-1962, resulted in severe limb anomalies
  • Phenytoin: anti-convulsant, results in digit hypoplasia
  • Warfarin: anti-coagulant, results in shortened fingers and abnormal chondrogenesis

Question 4

A 20 yr old male presents to the emergency department after a FOOSH. There is pain and swelling at the base of the thumb. On PE the patient is tender over the anatomical snuff box. What bone has the patient most likely fractured?

Answer 4

Scaphoid Fracture

• The scaphoid is often fractured due to FOOSh
  
  • Often misdiagnosied as a sprain, because it can be difficult to see on a radiograph
  • Blood supply is poor, so healing may take more than three months
  • Necrosis of the fragment may occur

Question 5

Describe the difference between a shoulder separation and dislocation.

Answer 5

The highly mobile nature of the shoulder makes it easy to injure.

• Shoulder separation: dislocation of the AC joint, often with associated AC and coracoclavicular ligament tear
  
  • Usually results form a direct blow, or FOOSH
  • Common in contact sports
• Shoulder dislocation: dislocation of the glenohumeral joint
  
  • Usually antero-inferior displacement
  • Often accompanied by capsule tears

Question 6

What is contained within the carpal tunnel?

Answer 6

Carpal tunnel is formed by the flexor retinaculum, it contains:

• Tendons of the superficial and deep digital flexors
  
  • Flexor digitorum superficialis tendons
  • Flexor digitorum profundus tendons
  • Flexor pollicis longus tendon
  • Flexor carpia radialis tendon
• Median nerve
• Reduction in the size of the carpal tunnel (ex. inflammation of the tendon sheathes) causes pressure on the median n.

Question 7

What is Erb’s palsy?

Answer 7

Erb’s Palsy

• Superior brachial plexus injury due to excessive stretching of the neck and depression of the shoulder
• Erb’s palsy affects muscles supplied by C5-C6
  
  • Musculocutaneous n.
  • Subscapular n.
  • Axillary n.

Question 8

What is Klumpke’s palsy?

Answer 8

The inferior part of the brachial plexus may be injured by excessive stretching of the arm ex. falling from a ladder and grabbing onto something to stop the fall

• This results in Klumpke’s palsy
• May be treated surgically by removing scar tissue and/or inserting nerve grafts

Question 9

Why is the PCL torn less often than the ACL?

Answer 9

The PCL is shorter and stronger and stronger than the ACL; consequently it is not torn nearly as often as the ACL.

Question 10

What is the most common MOI of an ankle sprain? What ligament is commonly sprained?

Answer 10

The LCL is weak and often sprained. It resists inversion of the foot. One or more of its parts may tear in the common inversion ankle injury; when this happens, the ligaments usually tear from anterior to posterior, with the anterior talofibular ligament being torn first.

Question 11

A direct trauma to the head of the fibula in a patient who presents with foot drop (inability to dorsiflex at the ankle) and an inability to dorsiflex the foot suggest inury to what nerve?

Answer 11

Common Fibular N.

This is the most commonly injured nerve of the lower limb. This neve is vulnerable to compression injury, usually from direct trauma, where it wraps around the head of the fibula. When injured, the patient may present with footdrop (inability to dorsiflex at the ankle) and an inability to ever the foot.

Question 12

Posterior compartment syndrome of the lower leg may result in the injury of which nerve?

Answer 12

Tibial N.

Question 13

A fracture of the surgical neck of the humerus may injury which nerve?

Answer 13

Axillary N.

Question 14

A midshaft fracture of the humerus may injur which nerve?

Answer 14

Radial N.

Question 15

What type of dislocation is most common for the glenohumeral joint? What nerves would be at risk in this injury?

Answer 15

Musculocutaneous N. and Axillary N. may be at risk for injury in an anterior glenohumeral jt dislocation.

Question 16

What is the most common type of elbow dislocations?

Answer 16

Posterior

• Dislocations of the elbow jt are 3rd in frequency after shoulder and finger dislocations and usually result from a FOOSH
• Posterior dislocations are the most common type

Question 17

What is a Colles’ fracture?

Answer 17

Colle’s fracture - a fracture of the distal radius, commonly occurring from a FOOSH, in such fractures the distal fragment of the radius is forced proximally and dorsally; resulting in a ‘dinner fork’ deformity.

Question 18

Tapping the biceps tendon to elicit the biceps tendon reflex tests which spinal cord segments?

Answer 18

Tapping the biceps tendon elicits the biceps tendon reflex, testing spinal cord segments C5 and C6. The biceps is tested clinically by having a patient flex the supinated forearm against resistance and watching for the distinct contraction of the biceps in the anterior arm. This action tests the integrity of the musculocutaneous nerve.

Question 19

Tapping the triceps tendon elicits the triceps reflex, testing which spinal cord segments?

Answer 19

C7 and C8

Question 20

What is cubital tunnel syndrome?

Answer 20

Cubital tunnel syndrome

As the ulnar n. passes between the 2 heads of the flexor carpi ulnaris, the nerve can become compressed, leading to a cubital tunnel syndrome. This syndrome is 2nd to carpal tunnel syndrome. Compression may be especially acute as the elbow is flexed because this narrows the space between the 2 muscle heads.

Question 21

What are the risk factors for developmental dysplasia of the hip? How do you screen for it and what is the treatment?

Answer 21

Developmental Dysplasia of the Hip

• RFs = Fs
  
  • Female, First born, Family history, leFt hip, Frank breech (legs straight with toes near head)
• Presentation: asymmetry
  
  • Raise hips looking for subluxation
  • Galeazzi test
  • If suspected, the best test is U/S (++ sensitive)
• Treatment: abduction of the hip replaces femoral head in acetabulum
  
  • Harness (abduction and external rotation)
  • Catch early, HUGE operation to fix later

Question 22

What is Leg-Calve-Perthes disease?

Answer 22

Leg-Calve-Perthes Disease

• Idiopathic osteonecrosis of femoral head in kids ~5-8 yrs old
• Prognosis better with younger age - more time for remodeling
• More common in MALES

Question 23

What is a slipped capital femoral epiphysis?

Answer 23

Slipped Capital Femoral Epiphysis

• Epiphysis slips off back of femoral neck in kids ~10-15 yrs old
• More common in MALES
• Can present with knee pain - easy to miss hip
• Goal is to get closure of grwoth plate as fast as possible (unstable)

Question 24

A pt. presents to emergency with ++ bilateral buttock and lower extremity pain. The pt. complains of bladder incontinence. These symptoms have developed over the last 24 hrs. The personal medical history reveals a history of osteoarthritis in the spine. What is at the top of your differential? What might you see on PE? What is the treatment?

Answer 24

Cauda Equina Syndrome - compression or irritation of lumbosacral n. roots below the conus medullaris (below L2)

• Common causes: herniated disc +/- spinal stenosis, vertebral fracture and tumour
• Presentation: weakness/paraparesis in multiple root distribution, reduced deep tendon reflexes (knee or ankle), urinary retention (or overflow incontinence), fecal incontinence, sciatica, saddle anesthesia (S2-S5; evident on DRE)
• MEDICAL EMERGENCY: surgical decompression (<48hr) to preserve bowel, bladder and sexual function +/- prevent paraplegia

Question 25

A pt. comes into see their family physician and complains of a gradual and progressive back and leg pain with standing and walking. They say that their pain is relieved by sitting and lying down. What is likely going on here? What treatment can you offer now? What are the next steps?

Answer 25

Lumbar Spinal Stenosis

• Congenital narrowing of spinal canal combined with degenerative changes (herniated disc, hypertrophied facet jts, and ligamentum flavum)
• Presentation: gradually progressive back and leg pain with standing and walking that is relieved by sitting or lying down, neurologic exam may be normal, including straight leg raise
• Investigations: MRI
• Treatment: conservative = NSAIDs, analgesia, Surgical = laminectomy with root decompression