Clinical correlations of lower limb

Clinical correlations of lower limb

Clinical correlations of lower limb

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Nerve Injuries - Shocking Tales

  • Common Peroneal (Fibular) N. (L4-S2):
    • Injury: Most common; fibular neck fracture, lateral compression.
    • Motor: Foot drop (impaired dorsiflexion/eversion). Unopposed plantarflexion/inversion.
    • Sensory: Anterolateral leg & dorsum of foot.
    • 📌 PED: Peroneal Everts & Dorsiflexes.
  • Tibial N. (L4-S3):
    • Injury: Popliteal fossa compression (Baker's cyst), tarsal tunnel syndrome.
    • Motor: Can't stand on tiptoes (impaired plantarflexion/inversion).
    • Sensory: Sole of the foot.
    • 📌 TIP: Tibial Inverts & Plantarflexes.
  • Superior Gluteal N. (L4-S1):
    • Injury: Iatrogenic (misplaced gluteal injection).
    • Motor: Trendelenburg gait (pelvic drop on contralateral side).

⭐ Injury to the common peroneal nerve often presents as "foot drop." Patients may develop a high-stepping "steppage gait" to compensate and avoid tripping over their toes.

Normal vs. Trendelenburg Gait

Vascular Issues - Plumbing Problems

  • Peripheral Artery Disease (PAD):
    • Atherosclerosis → intermittent claudication (cramping pain on exertion).
    • Key diagnostic: Ankle-Brachial Index (ABI) < 0.9.
    • Signs: cool, pale, hairless skin; non-healing ulcers.
  • Deep Vein Thrombosis (DVT):
    • Clot in a deep vein, usually the calf.
    • 📌 Virchow's Triad: Stasis, Hypercoagulability, Endothelial damage.
    • Presents as unilateral leg swelling, warmth, and erythema.
  • Varicose Veins:
    • Incompetent valves in superficial veins → dilated, tortuous vessels.

⭐ Proximal DVTs (popliteal, femoral, iliac) are far more likely to embolize to the lungs, causing a pulmonary embolism, than distal (calf) DVTs.

Ankle-Brachial Index (ABI) Measurement and Interpretation

MSK Injuries - Broken Beams

  • Femoral Neck Fracture: Presents with a shortened, externally rotated leg. High risk of avascular necrosis (AVN) due to tenuous blood supply.
  • Tibial Plateau Fracture: Often from a direct valgus force (e.g., car bumper). Complications include popliteal artery injury and common peroneal nerve damage (foot drop).
  • Ankle Fracture: Always examine the proximal fibula with medial malleolar injuries to rule out a Maisonneuve fracture, which indicates syndesmotic instability.
  • Stress Fracture: Common in athletes and military recruits. The 2nd metatarsal is the most frequent site.

⭐ The medial circumflex femoral artery is the primary blood supply to the femoral head. Intracapsular femoral neck fractures disrupt this artery, leading to a high rate of avascular necrosis.

Blood supply to femoral head and neck

Gait Analysis - The Limp Bizkit

  • Antalgic Gait:
    • Cause: Pain (e.g., trauma, osteoarthritis).
    • Presentation: Shortened stance phase on the affected side to minimize weight-bearing.
  • Trendelenburg Gait:
    • Cause: Weakness of hip abductors (gluteus medius/minimus), superior gluteal nerve injury.
    • Presentation: Pelvis drops on the contralateral (unaffected) side during swing phase.
  • Steppage (Equine) Gait:
    • Cause: Foot drop due to common peroneal nerve palsy or L5 radiculopathy.
    • Presentation: Exaggerated hip/knee flexion to clear the foot; may hear a "foot slap."

Trendelenburg Sign: A positive sign (pelvic drop) on the right side indicates a lesion of the left superior gluteal nerve.

Trendelenburg vs. Normal Gait: Pelvic Stability

High‑Yield Points - ⚡ Biggest Takeaways

  • Femoral neck fractures risk avascular necrosis of the femoral head by disrupting the medial circumflex femoral artery.
  • Common fibular nerve injury at the fibular neck causes foot drop (impaired dorsiflexion and eversion).
  • ACL tears, common in athletes, result from pivoting and show a positive anterior drawer sign.
  • The "unhappy triad" is a combined injury of the ACL, MCL, and medial meniscus.
  • Achilles tendon rupture presents with a palpable gap and a positive Thompson test.
  • Deep vein thrombosis (DVT) is a major source of life-threatening pulmonary emboli.

Practice Questions: Clinical correlations of lower limb

Test your understanding with these related questions

A 36-year-old woman comes to the physician because of new onset limping. For the past 2 weeks, she has had a tendency to trip over her left foot unless she lifts her left leg higher while walking. She has not had any trauma to the leg. She works as a flight attendant and wears compression stockings to work. Her vital signs are within normal limits. Physical examination shows weakness of left foot dorsiflexion against minimal resistance. There is reduced sensation to light touch over the dorsum of the left foot, including the web space between the 1st and 2nd digit. Further evaluation is most likely to show which of the following?

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Flashcards: Clinical correlations of lower limb

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What kind of rotation do the following muscles allow the hip to do?_____Gluteus medius (F)Gluteus minimus (F)Tensor fascia lata (AB)

TAP TO REVEAL ANSWER

What kind of rotation do the following muscles allow the hip to do?_____Gluteus medius (F)Gluteus minimus (F)Tensor fascia lata (AB)

Internal rotation

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