A 70-year-old man with a recent above-the-knee amputation of the left lower extremity, due to wet gangrene secondary to refractory peripheral artery disease, presents with weakness and dizziness. He says that the symptoms began acutely 24 hours after surgery and have not improved. The amputation was complicated by substantial blood loss. He was placed on empiric antibiotic therapy with ciprofloxacin and clindamycin before the procedure, and blood and wound culture results are still pending. The medical history is significant for type 2 diabetes mellitus and hypertension. Current medications are metformin and lisinopril. The family history is significant for type 2 diabetes mellitus in both parents. Review of symptoms is significant for palpitations and a mild headache for the past 24 hours. His temperature is 38.2°C (100.8°F); blood pressure, 120/70 mm Hg (supine); pulse, 102/min; respiratory rate, 16/min; and oxygen saturation, 99% on room air. When standing, the blood pressure is 90/65 mm Hg and the pulse is 115/min. On physical examination, the patient appears pale and listless. The surgical amputation site does not show any signs of ongoing blood loss or infection. Laboratory tests and an ECG are pending. Which of the following is the next best step in management?

Administer IV fluids and withhold lisinopril

Administer oral fludrocortisone

An 8-year-old boy and his 26-year-old babysitter are brought into the emergency department with severe injuries caused by a motor vehicle accident. The child is wheeled to the pediatric intensive care unit with a severe injury to his right arm, as well as other external and internal injuries. He is hemorrhaging and found to be hemodynamically unstable. He subsequently requires transfusion and surgery, and he is currently unconscious. The pediatric trauma surgeon evaluates the child’s arm and realizes it will need to be amputated at the elbow. Which of the following is the most appropriate course of action to take with regards to the amputation?

Amputate the child’s arm at the elbow joint

Obtain an emergency court order from a judge to obtain consent to amputate the child’s arm

Find the child’s parents to obtain consent to amputate the child’s arm

Wait for the child’s babysitter to recover from her injuries to obtain her consent to amputate the child’s arm

Wait for the child to gain consciousness to obtain his consent to amputate his arm

A 73-year-old man comes to the physician because of worsening bilateral lower extremity pain for the past 8 months. The pain begins after walking one to two blocks and radiates bilaterally down the buttocks with cramping and tingling. He reports that the pain is worse while walking downhill and is relieved by sitting and leaning forward. He has hypertension, hyperlipidemia, and type 2 diabetes mellitus. He had a myocardial infarction at the age of 55 years and an abdominal aortic aneurysm repair at the age of 60 years. He has smoked one pack of cigarettes daily for the past 30 years. He does not drink alcohol or use illicit drugs. His current medications include sitagliptin, metformin, atorvastatin, metoprolol succinate, amlodipine, and hydrochlorothiazide. His temperature is 37.5°C (99.5°F), pulse is 82/min, respirations are 17/min, and blood pressure is 150/87 mm Hg. Examination shows full muscle strength. Sensation is reduced bilaterally in the feet and toes. Straight leg raise is negative. X-ray of the spine shows degenerative changes. Which of the following is the most appropriate next step in diagnosis?

Measurement of the ankle brachial index

Measurement of serum creatine kinase

An 11-year-old boy with a history of attention deficit disorder presents to a general medicine clinic with leg pain. He is accompanied by his mother. He reports dull, throbbing, diffuse pain in his bilateral lower extremities. He reports that the pain feels deep in his muscles. He has awakened several times at night with the pain, and his symptoms tend to be better during the daylight hours. He denies fatigue, fever, or pain in his joints. On physical examination, his vital signs are stable, and he is afebrile. Physical examination reveals full range of motion in the hip and knee joints without pain. He has no joint effusions, erythema, or warmth. What is the next best step in management?

Lower extremity venous ultrasound

A 31-year-old man presents to the Emergency Department with severe left leg pain and paresthesias 4 hours after his leg got trapped by the closing door of a bus. Initially, he had a mild pain which gradually increased to unbearable levels. Past medical history is noncontributory. In the Emergency Department, his blood pressure is 130/80 mm Hg, heart rate is 87/min, respiratory rate is 14/min, and temperature is 36.8℃ (98.2℉). On physical exam, his left calf is firm and severely tender on palpation. The patient cannot actively dorsiflex his left foot, and passive dorsiflexion is limited. Posterior tibial and dorsalis pedis pulses are 2+ in the right leg and 1+ in the left leg. Axial load does not increase the pain. Which of the following is the best next step in the management of this patient?

Lower limb X-ray in two projections

Paramedics are called to a 35-year-old man who had accidentally amputated his left index finger tip with a knife. He has no significant past medical history. His temperature is 37.2°C (99°F), pulse is 96/min, and blood pressure is 112/72 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 99%. His left index finger is amputated distal to the distal interphalangeal joint at the level of the nail bed, and exposed bone is visible. There is profuse bleeding from the wound site. His ability to flex, extend, abduct, and adduct the joints is preserved and sensation is intact. The remainder of the examination shows no abnormalities. Which of the following is the most appropriate next step prior to transporting this patient to the emergency department?

Wrap finger tip in gauze damp with saline in a sealed plastic bag placed on ice water

Preserve finger tip in warm saline water

Wrap finger in gauze wet with iodine in a sealed plastic bag placed on ice

Place finger tip on ice in a sealed plastic bag

Preserve finger tip in cooled saline water

Amputation indications and techniques for USMLE Step 3: High-Yield Surgery Lessons

Core concept - Point of No Return

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🔪 Management - The Great Divide

Lower Extremity Amputation Levels

Amputation Techniques:
- Guillotine (Open): All tissues transected at the same level; wound left open.
  - Indication: Severe infection (e.g., gas gangrene), gross contamination, damage control surgery.
  - Follow-up: Requires delayed closure or revision to a definitive flap amputation.
- Flap (Closed): Definitive procedure. Skin and muscle flaps are shaped for primary closure over the bone.
  - Example: Long posterior flap in BKA preserves gastrocnemius blood supply.
Soft Tissue Handling:
- Myoplasty: Suture opposing muscle groups to each other over the bone end.
- Myodesis: Suture muscle or tendon directly to bone via drill holes. More stable; prevents muscle retraction.
- Nerve Management (Traction Neurectomy): Nerve is gently pulled taut, sharply cut, and allowed to retract into healthy tissue.
  - 💡 Prevents painful neuroma formation at the stump end.

⭐ Preserving the knee joint in a below-knee amputation (BKA) results in significantly better prosthetic function and lower energy expenditure compared to an above-knee amputation (AKA).

🤕 Complications - The Aftermath

Early (Days to Weeks)
- Hematoma: Risk of flap necrosis & infection; may require evacuation.
- Infection: Cellulitis, abscess, or osteomyelitis.
- Wound Dehiscence: Separation of wound edges.
- ⚠️ DVT/PE: High risk due to immobility; requires prophylaxis.
Late (Weeks to Years)
- Phantom Limb Sensation: Common, non-painful awareness of the limb.
- Phantom Limb Pain: Pathological pain; distinct from sensation.
- Neuroma: Painful mass of disorganized nerve tissue at the stump end.
- Contractures: Joint deformity (hip/knee flexion); prevent with early PT.
- Heterotopic Ossification: Abnormal bone growth in soft tissue.

⭐ Phantom limb pain is a true central pain syndrome. Treat with multimodal therapy: gabapentin, TCAs (amitriptyline), mirror therapy, and TENS.

⚡ Biggest Takeaways

Top Indication: Peripheral vascular disease (PVD), often with diabetes, is the leading cause. Others include severe trauma, uncontrolled infection, and malignancy.

Pre-op Viability: Amputation level is guided by tissue perfusion. Poor healing is predicted by ABI < 0.5 or transcutaneous O₂ (TcPO₂) < 30 mmHg.

Surgical Pearls: Myodesis (muscle to bone) provides superior stump stability. Perform traction neurectomy to prevent painful neuromas.

Major Complications: Phantom limb pain is central neuropathic pain (treat with gabapentin/TCAs). Prevent hip/knee flexion contractures with early PT.

Functional Goal: Preserve length, prioritizing the knee joint. A below-knee amputation (BKA) is functionally superior to an above-knee (AKA).

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