A 6-week-old boy is brought for routine examination at his pediatrician’s office. The patient was born at 39 weeks to a 26-year-old G1P1 mother by normal vaginal delivery. External cephalic version was performed successfully at 37 weeks for breech presentation. Pregnancy was complicated by gestational diabetes that was well-controlled with insulin. The patient’s maternal grandmother has early onset osteoporosis. On physical examination, the left hip dislocates posteriorly with adduction and depression of a flexed femur. An ultrasound is obtained that reveals left acetabular dysplasia and a dislocated left femur. Which of the following is the next best step in management?

Closed reduction and spica casting

Open reduction and femoral osteotomy

A 6-year-old boy is brought to the physician because of right hip pain that started that afternoon. His mother reports that he has also been limping since the pain developed. He says that the pain worsens when he moves or walks. He participated in a dance recital yesterday, but his mother believes that he was not injured at the time. He was born at term and has been healthy except for an episode of nasal congestion and mild cough 10 days ago. His mother has rheumatoid arthritis and his grandmother has osteoporosis. He is at the 50th percentile for height and 50th percentile for weight. His temperature is 37.5°C (99.6°F), pulse is 105/min, respirations are 16/min, and blood pressure is 90/78 mm Hg. His right hip is slightly abducted and externally rotated. Examination shows no tenderness, warmth, or erythema. He is able to bear weight. The remainder of the examination shows no abnormalities. Laboratory studies show a hemoglobin concentration of 12.3 g/dL, a leukocyte count of 8,500/mm3, and an erythrocyte sedimentation rate of 12 mm/h. Ultrasound of the right hip shows increased fluid within the joint. X-ray of the hips shows no abnormalities. Which of the following is the most likely diagnosis?

Slipped capital femoral epiphysis

Developmental dysplasia of the hip

A 7-year-old boy is brought to the physician by his mother because of a limp for the last 3 weeks. He has also had right hip pain during this period. The pain is aggravated when he runs. He had a runny nose and fever around a month ago that resolved with over-the-counter medications. He has no history of serious illness. His development is adequate for his age. His immunizations are up-to-date. He appears healthy. He is at the 60th percentile for height and at 65th percentile for weight. Vital signs are within normal limits. Examination shows an antalgic gait. The right groin is tender to palpation. Internal rotation and abduction of the right hip is limited by pain. The remainder of the examination shows no abnormalities. His hemoglobin concentration is 11.6 g/dL, leukocyte count is 8,900/mm3, and platelet count is 130,000/mm3. An x-ray of the pelvis is shown. Which of the following is the most likely underlying mechanism?

Bacterial infection of the joint

Unstable proximal femoral growth plate

Immune-mediated synovial inflammation

A patient presents to the emergency department with arm pain. The patient recently experienced an open fracture of his radius when he fell from a ladder while cleaning his house. Surgical reduction took place and the patient's forearm was put in a cast. Since then, the patient has experienced worsening pain in his arm. The patient has a past medical history of hypertension and asthma. His current medications include albuterol, fluticasone, loratadine, and lisinopril. His temperature is 99.5°F (37.5°C), blood pressure is 150/95 mmHg, pulse is 90/min, respirations are 19/min, and oxygen saturation is 99% on room air. The patient's cast is removed. On physical exam, the patient's left arm is tender to palpation. Passive motion of the patient's wrist and fingers elicits severe pain. The patient's left radial and ulnar pulse are both palpable and regular. The forearm is soft and does not demonstrate any bruising but is tender to palpation. Which of the following is the next best step in management?

Measurement of compartment pressure

A 43-year-old man is brought to the emergency department 40 minutes after falling off a 10-foot ladder. He has severe pain and swelling of his right ankle and is unable to walk. He did not lose consciousness after the fall. He has no nausea. He appears uncomfortable. His temperature is 37°C (98.6°F), pulse is 98/min, respirations are 16/min, and blood pressure is 110/80 mm Hg. He is alert and oriented to person, place, and time. Examination shows multiple abrasions over both lower extremities. There is swelling and tenderness of the right ankle; range of motion is limited by pain. The remainder of the examination shows no abnormalities. An x-ray of the ankle shows an extra-articular calcaneal fracture. Intravenous analgesia is administered. Which of the following is the most appropriate next step in the management of this patient?

Short leg splint and orthopedic consultation

Broad-spectrum antibiotic therapy

Open reduction and internal fixation

A 25-year-old man comes to the physician because of left-sided knee pain for 2 weeks. The pain started while playing basketball after suddenly hearing a popping sound. He has been unable to run since this incident. He has asthma, allergic rhinitis, and had a progressive bilateral sensorineural hearing impairment at birth treated with cochlear implants. His only medication is a salbutamol inhaler. The patient appears healthy and well-nourished. His temperature is 37°C (98.6°F), pulse is 67/min, and blood pressure is 120/80 mm Hg. Examination of the left knee shows medial joint line tenderness. Total knee extension is not possible and a clicking sound is heard when the knee is extended. An x-ray of the left knee shows no abnormalities. Which of the following is the most appropriate next step in the management of this patient?

Arthrocentesis of the left knee

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

Pediatric orthopedic emergencies for USMLE Step 2 CK: High-Yield Surgery Lessons

🦴 Tiny Bones, Big Trouble

Emergency	Presentation	Key Risk	Management
Septic Arthritis	Infant/toddler, fever, non-weight bearing, hip pain	Avascular Necrosis (AVN)	Arthrocentesis, I&D, IV Abx
Supracondylar Fx	FOOSH, elbow swelling, "S"-shaped deformity	Median n. / Brachial a. injury → Volkmann's contracture	Closed reduction & pinning
SCFE	Obese adolescent, limp, hip/thigh/knee pain	AVN, Chondrolysis	Surgical pinning (in situ)
Compartment Syndrome	Pain out of proportion, tense/swollen limb	Permanent muscle/nerve damage	⚠️ Emergent Fasciotomy

🤕 Ouchies & Odd Angles

Universal Signs: Limp, refusal to bear weight, focal tenderness, swelling, erythema, deformity (angulation, rotation), ↓ range of motion.
Specific Postures:
- Septic Hip: Held in flexion, abduction, & external rotation.
- SCFE: Obligatory external rotation with passive hip flexion.

Condition	Classic Patient	Key Findings
Septic Arthritis	Toddler, acute fever	Severe pain on passive motion, won't bear weight
DDH	Newborn/Infant	+Ortolani/Barlow, asymmetric gluteal folds, limited abduction
SCFE	Obese adolescent	Groin/thigh/knee pain, painful limp, externally rotated leg
LCP	Young boy (4-8 yo)	Insidious, often painless limp, ↓ internal rotation

⭐ High-Yield: Hip pathology (like SCFE or LCP) frequently presents as referred pain to the knee. Always examine the hip in a child with knee pain

🚩 Diagnosis - Spotting Red Flags

Systemic Signs: Fever, irritability, malaise, poor feeding.
Limb-Specific Signs:
- Refusal to bear weight: The most sensitive sign for serious pathology.
- Severe pain on passive motion: Suggests joint or deep infection/inflammation.
- Night cries: Can indicate constant, severe pain (e.g., osteomyelitis, tumor).
Septic Arthritis (Hip): 📌 Kocher Criteria
- Non-weight-bearing on affected side
- Fever > 38.5°C ($101.3^\circ F$)
- ESR > 40 mm/hr
- WBC > 12,000/mm³
Compartment Syndrome:
- ⚠️ Pain out of proportion to injury is the key early sign.
- The 6 P's: Pain, Pallor, Paresthesia, Pulselessness (late), Paralysis (late), Poikilothermia.

⭐ A child holding a limb in a specific position (e.g., hip flexed, abducted, externally rotated for septic arthritis) is a major red flag for minimizing pain from an effusion.

🚑 Management - Fix 'Em Fast

Septic Arthritis:
- Urgent surgical Incision & Drainage (I&D).
- IV antibiotics (e.g., Vancomycin, Ceftriaxone) guided by Gram stain/culture.
SCFE (Slipped Capital Femoral Epiphysis):
- Make patient non-weight bearing immediately.
- Surgical fixation: In situ pinning with a single screw.
Compartment Syndrome:
- ⚠️ Clinical diagnosis is paramount; do not delay for pressure measurements.
- Emergent fasciotomy.
Displaced Supracondylar Fracture:
- Assess neurovascular status (brachial artery, median nerve).
- Urgent closed reduction and percutaneous pinning (CRPP).

⭐ For SCFE, prophylactic pinning of the contralateral, asymptomatic hip is often performed due to the high risk (20-40%) of a subsequent contralateral slip.

Bilateral SCFE pinning on hip X-ray

⚠️ Complications - Future Trouble Codes

Avascular Necrosis (AVN): High risk in SCFE, DDH, and femoral neck fractures.
Growth Arrest/Deformity: Physeal injuries (Salter-Harris III-V) can cause limb length discrepancy or angulation.
Joint Destruction: Untreated septic arthritis leads to rapid cartilage loss.
Permanent Deficits: Compartment syndrome causes Volkmann's ischemic contracture.

⭐ AVN of the femoral head is a dreaded complication of unstable SCFE, often requiring future arthroplasty.

⚡ Biggest Takeaways

Septic arthritis is a surgical emergency in a febrile child refusing to bear weight. Staph aureus is the most common cause.

SCFE affects obese adolescents with hip/knee pain. Requires urgent surgical pinning to prevent AVN.

Supracondylar fracture risks brachial artery/median nerve injury (Volkmann's contracture).

DDH is screened with Barlow/Ortolani. Diagnose with ultrasound (<4-6 mo) or X-ray (>4-6 mo).

Legg-Calvé-Perthes is idiopathic avascular necrosis of the femoral head in children 4-8 years old.

Nursemaid's elbow (radial head subluxation) is reduced by supination and flexion.

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