case studies - lower limb

The ACL originates from which structure?

Inserts on which structure?

Origin: lateral femoral condyle/intercondylar area of femur

Insertion: anterior intercondylar area of tibia

What is the primary function of the ACL?

Prevents anterior translation of the tibia on the femur; also helps control rotational stability

Why does the patient develop swelling within hours of an ACL tear?

ACL tears commonly cause hemarthrosis due to bleeding into the joint

Which compartment in the thigh contains the quadriceps muscles?Where does this insert?

Anterior thigh compartment

Inserts via quadriceps tendon onto patella, then patellar ligament to tibial tuberosity

Why can a patient have a normal xray with a complete ACL tear?

Xrays do not show ligaments

think of the clinical story I mentioned with the quadriceps tendon rupture that was a CLINICAL diagnosis, also seen on MRI

A patient with an ACL tear also reports numbness in the first dorsal web space of the foot. Which nerve should be evaluated?

Deep fibular nerve

The femoral neck connects which two structures?

Femoral head to shaft

Which artery provides the majority of blood supply to the adult femoral head?

Medial circumflex femoral artery

Why are femoral neck fractures particularly concerning?

They have an inherent risk of avascular necrosis due to disruption of blood supply at medial circumflex femoral artery

Which physical exam finding is classically associated with a displaced femoral neck fracture?

SHORTENED externally rotated leg

The femoral head articulates with which structure?

Acetabulum

Which bony landmark serves as the insertion site for the iliopsoas muscle?

Lesser trochanter

Which structure passes through the femoral triangle?

Femoral nerve, artery, vein, lymphatics - remember the NAVL mnemonic we discussed in lab

Why are the elderly particularly susceptible to femoral neck fractures following low-energy falls?

Osteoporosis, impaired balance

Why might a patient with a femoral neck fracture have normal xrays but persistent inability to bear weight? Which test would you then order for further evaluation?

You can have an occult femoral neck fracture, which isn't readily seen on xray. You would then order an MRI for further evaluation.

CC: I keep tripping over my foot when I walk.

HPI: A 19-year-old male collegiate football player presents to the sports medicine clinic complaining of difficulty lifting his right foot while walking.

Range of Motion: Weak active dorsiflexion. Weak toe extension. Weak foot eversion. Normal plantar flexion

Diagnosis? What nerve is likely injured in this patient? This is a branch of which nerve?

Common fibular nerve which is a branch of the sciatic nerve

Why is the common fibular nerve particularly vulnerable to injury?

It wraps around the fibular neck, making it prone to injury if the fibula is injured

What gait abnormality does this patient represent as a result of a common fibular nerve injury? Why do they do this?

Foot drop results in steppage gait, patient kicks foot out to combat the drop

The common fibular nerve innervates what compartment of the leg?

Divides into superficial and deep

Deep innervates the anterior compartment

Superficial innervates the lateral compartment

Which muscle is responsible for dorsiflexion of the foot?

Tibialis anterior

Which compartment of the leg contains the fibularis longus and fibularis brevis?

Lateral compartment

Which bony landmark should be palpated in this patient with a common fibular nerve injury?

Fibular neck, as the nerve wraps around it

Why does plantar flexion remain intact in this patient with a common fibular nerve injury?

Plantar flexors are innervated by the tibial nerve, not common fibular

How would you differentiate an injury to the common fibular nerve from an L5 radiculopathy?

If a patient had back pain or spasm, or paresthesias higher up you would think this would be L5 radiculopathy

Why might frequent leg-crossing increase risk of injury to the common fibular nerve?

Leg crossing compresses the same nerve, over time can become susceptible to paresthesias/injury

In which direction do most patellar dislocations occur?

Laterally

The patella articulates with which structure of the femur?

Patellar surface/trochlear groove of the femur

What is the primary function of the patella?

It increases the leverage of the quadriceps, this allows leg extension

Which muscle helps stabilize the patella medially?

Medial patellofemoral ligament

The patellar ligament inserts on which structure?

Tibial tuberosity

Which movement typically reproduces symptoms after a patellar dislocation?

Knee flexion/extension

Which structure forms the superior attachment of the quadriceps tendon?

Quadriceps muscles: Rectus femoris

Vastus medialis

Vastus lateralis

Vastus intermedius

Why are adolescent females at increased risk of patellar instability?

Typically have more ligamentous laxity, also have a more shallow trochlear groove

Why might a patient experience recurrent patellar dislocations after the first event?

Once this happens, the ligaments are not as strong as they once were

prone to recurrence

Which bone forms the lateral malleolus?

Fibula

Which bone forms the medial malleolus?

Tibia

What ligament is most commonly injured during an inversion ankle injury?a) Deltoid ligament

b) Calcaneofibular ligament

c) Anterior talofibular ligament

d) Posterior talofibular ligament

e) Spring ligament

c) Anterior talofibular ligament

What is the primary function of the lateral malleolus?

Lateral ankle stability

Which artery is palpated on the dorsum of the foot during a vascular examination?

Dorsalis pedis

The tibia and fibula are connected distally by what structure?

Interosseous ligament

What nerve provides sensation to the first dorsal web space of the foot?

Deep fibular nerve

Injury to this nerve would most likely produce which finding?

a) Loss of plantar flexion

b) Loss of dorsiflexion

c) Loss of knee extension

d) Loss of hip flexion

e) Loss of toe flexion

b) Loss of dorsiflexion

A patient is unable to dorsiflex the foot following trauma. What compartment of muscles would likely be affected? What clinical finding would be expected?

Anterior compartment, foot drop/steppage gait

Why is it important to examine the proximal fibula in a patient presenting with an ankle injury?

Rule out a proximal fracture or proximal injury, can result in syndesmotic ankle injury (tibiofibular syndesmosis)

A patient presents after an ankle injury with tenderness over the base of the 5th metatarsal. What additional injury should be suspected?

Jones fracture

What is the longest and strongest bone in the human body?

The femur

What major artery travels through the adductor canal and becomes the popliteal artery?

Femoral artery

Why are femoral shaft fractures often associated with significant bloodloss?

Can hide 1-2 L of blood loss because highly vascularized, large thigh compartment can hold a lot of blood loss

Which muscle group is primarily responsible for extension of the knee?

Quadriceps

What nerve innervates this muscle group?

Femoral nerve

Which muscle inserts on the lesser trochanter?

Iliopsoas

What movement is produced by this muscle?

Hip flexion

The femoral neck receives most of its blood supply from which vessel?

Medial circumflex femoral artery

Why is this blood supply clinically important?

Disruption of this can cause avascular necrosis of the femoral head

A patient with a femoral shaft fracture develops numbness over the anterior thigh and weakness with knee extension. Which nerve is most likely injured?

a) Sciatic nerve

b) Tibial nerve

c) Femoral nerve

d) Obturator nerve

e) Common fibular nerve

c) Femoral nerve

Which compartment of the thigh contains the hamstring muscles?

Posterior compartment

What nerve innervates the hamstring muscles?

Sciatic nerve - tibial division for most, though common fibular portion for short head of biceps femoris

What action is shared by all hamstring muscles?

Knee flexion

Which compartment of the thigh is primarily responsible for adduction?

Medial compartment

What nerve innervates most muscles of this compartment?

Obturator nerve

Why are femur fractures considered potentially life-threatening injuries even when no external bleeding is present?

Can have severe occult blood lossIn addition to this life-threatening condition, can also have severe shock, fat embolism, and high risk of vascular injury

An elderly patient sustains a low-energy fall resulting in a femoral neck fracture. Why is this mechanism concerning?

Suggestive of osteoporosis (normally, younger/healthy patient would need higher energy)

A patient develops increasing pain, pain with passive stretch, paresthesias, and a tense swollen thigh several hours after injury. What complication should be suspected?

Compartment syndrome

Why should patients with high-energy femur fractures be evaluated for hip, knee, pelvic, and vascular injuries?

High energy trauma can transmit force to other structures

Where is the greater trochanter located?

Bony projection of proximal femur

Which muscle inserts onto the lateral surface of the greater trochanter?

Gluteus medius

What structure is inflamed in trochanteric bursitis?

Trochanteric bursa

What is the function of a bursa?

Reduces friction between tendons/muscles and bones

Which structure passes superior to the piriformis muscle?

a) Sciatic nerve

b) Superior gluteal nerve

c) Inferior gluteal nerve

d) Pudendal nerve

e) Posterior femoral cutaneous nerve

b) Superior gluteal nerve

What imaging modality is most useful for evaluating bursitis and gluteal tendon pathology? Why?

Ultrasound/MRI; Ultrasound can show bursal fluid and tendon thickening;

MRI is best for detailed soft tissue evaluation (this is why it is great for evaluation muscle/tendon ruptures as well)

What is the acetabulum?

Hip socket - formed by ilium, ischium, pubis

What structure articulates with the acetabulum?

The femur

What type of joint is formed between the femoral head and

acetabulum?

Ball-and-socket synovial joint

Which ligament is considered the strongest ligament in the human body?a) ACL

b) Deltoid ligament

c) Iliofemoral ligament

d) Inguinal ligament

e) Sacrospinous ligament

c) Iliofemoral ligament

Which muscle is the primary flexor of the hip?

Iliopsoas

Where does the iliopsoas muscle insert?

Lesser trochanter

What major artery passes deep to the inguinal ligament and enters the thigh?

Femoral artery

Which pulse is palpated midway between the ASIS and pubic tubercle?

Femoral pulse

Which nerve is responsible for sensation to the anterior thigh?

a) Sciatic nerve

b) Femoral nerve

c) Tibial nerve

d) Common fibular nerve

e) Superior gluteal nerve

b) Femoral nerve

Why is it important to perform a thorough neurovascular examination of the lower extremities in every patient with a pelvic fracture?

Pelvic fractures can injure femoral vessels, lumbosacral plexus, sciatic/femoral nerves, or cause occult bleeding

Why should a patient with a pelvic fracture be evaluated for associated hip injuries?

High energy trauma can injure structures proximally

Your stable patient with a pelvic fracture suddenly becomes hypotensive with a blood pressure of 68/40. What is a critical FIRST thing to do here? Why?

Place a pelvic binder!

Treat as hemorrhagic shock until proven otherwise

First: activate trauma/hemorrhage protocol, stabilize airway, breathing, circulation(ABCs), apply pelvic binder, obtain rapid IV/IO access (remember we saw an IO placement), transfuse blood products, and urgent trauma/IR/ortho involvement