Pediatrics (System-Integrated)

Slipped capital femoral epiphysis

Clinical Overview and When to Suspect SCFE

— Functionally, the femoral neck slips up and out while the head stays put — described as the femoral head "slipping off the neck like ice cream off a cone"

— Age 10–16 years, with peak in boys 12–14 and girls 10–13 (earlier because of earlier physeal closure)

— Obese adolescent (BMI ≥95th percentile in ~60–80%)

— Male > female (~1.5:1), African American and Pacific Islander disproportionately affected

— Bilateral in 20–40%; up to 50% develop contralateral slip within 18 months

— Mechanical overload across a physis weakened by obesity, rapid growth spurt, and relative femoral retroversion

— Endocrine risk when slip occurs outside the typical age window (<10 or >16 years), or in a non-obese/short child: hypothyroidism, panhypopituitarism, GH deficiency or GH therapy, hypogonadism, renal osteodystrophy, prior pelvic radiation

— Obese adolescent with limp + hip, thigh, or referred knee pain

— Externally rotated lower extremity, decreased internal rotation of the hip

— Insidious dull groin/thigh pain for weeks (stable) or sudden inability to bear weight (unstable)

Board pearl: Any adolescent with knee or thigh pain and a limp must have the hip examined and imaged — missing SCFE because you only x-rayed the knee is a classic Step 3 management error and a malpractice favorite. Referred obturator-nerve pain makes the knee the loudest complaint while the hip is the real problem.

Slipped capital femoral epiphysis (SCFE) is a Salter-Harris type I fracture through the proximal femoral physis in which the metaphysis (femoral neck) displaces anteriorly and externally rotates, while the epiphysis (femoral head) remains seated in the acetabulum

Epidemiology — the classic Step 3 patient:

Pathophysiology drivers:

When to suspect on the Step 3 stem:

Presentation Patterns and Key History

— Stable SCFE: patient can ambulate (with or without crutches); chronic dull pain for weeks to months; AVN risk <10%

— Unstable SCFE: patient cannot bear weight even with crutches; acute severe pain; AVN risk 20–50% — treat like an emergency

— Pre-slip: physeal widening without displacement; vague pain

— Acute: symptoms <3 weeks, often after minor trauma

— Chronic: symptoms >3 weeks, gradual remodeling

— Acute-on-chronic: background ache for months with sudden worsening

— Pain location: groin, anteromedial thigh, or KNEE — isolated knee pain in 15–50%

— Limp, often antalgic with foot externally rotated

— Difficulty with stairs, running, prolonged standing

— Minor or no trauma (a true high-energy injury suggests a different fracture)

— Age <10 or >16

— Height <10th percentile, delayed puberty

— Known hypothyroidism, panhypopituitarism, CKD on dialysis, GH replacement, prior cranial/pelvic radiation

— Bilateral simultaneous slips at presentation

Key distinction: Stable vs unstable is defined by the ability to bear weight — not by duration, not by displacement on x-ray, not by pain severity. A child with 6 months of pain who suddenly cannot walk has acute-on-chronic unstable SCFE. This single binary determines AVN risk counseling, OR timing, and reduction strategy on the boards.

Loder classification — the single most important historical distinction because it dictates urgency, weight-bearing status, and AVN risk

Temporal/clinical subtypes (less management impact than Loder but still tested):

Classic history elements to mine in the stem:

Critical historical red flags pushing toward endocrine workup:

Ask about family history of SCFE and prior contralateral hip pain (a previously "resolved" limp may have been a missed pre-slip)

Physical Exam Findings

— Affected leg held in external rotation and slight abduction, often shortened 1–2 cm in chronic slips

— Trendelenburg or antalgic gait in stable cases; refusal/inability to bear weight in unstable

— In unstable SCFE, the patient typically lies on the stretcher with hip flexed and externally rotated

— Drehmann sign: with the patient supine, passive flexion of the affected hip causes obligatory external rotation and abduction — the leg cannot be flexed in neutral

— Loss of internal rotation, abduction, and flexion; pain at extremes

— Compare to contralateral hip — limited IR may be the only sign of a contralateral pre-slip

— Tenderness over the anterior hip capsule/groin

— Pain with log-rolling the leg

— FABER and FADIR typically reproduce groin pain

— Coarse facies, bradycardia, delayed reflex relaxation → hypothyroidism

— Short stature, delayed puberty, visual field defects → pituitary disease

— Acanthosis nigricans, central obesity → metabolic syndrome (common comorbid finding)

— Growth charts: height and weight percentiles must be plotted on every SCFE evaluation

Step 3 management: On exam, obligatory external rotation with hip flexion (positive Drehmann) in an obese adolescent = SCFE until proven otherwise. Do not attempt to forcibly internally rotate or "reduce" the hip in the ED — this can convert a stable slip to unstable and triple the AVN risk. Make the patient non–weight-bearing immediately and order imaging.

Inspection and gait:

Range of motion — the pathognomonic finding:

Palpation and provocative tests:

Neurovascular exam: should be intact — abnormal findings suggest alternate diagnosis or, rarely, vascular compromise of the femoral head (an OR emergency)

General exam clues to underlying systemic disease:

Always examine the contralateral hip even if asymptomatic — silent slips are documented in up to 25%

Diagnostic Workup — Initial Imaging and Labs

— AP pelvis and bilateral frog-leg lateral (or true cross-table lateral if unstable — avoid frog-leg in unstable slip, as positioning can worsen displacement)

— Bilateral views are mandatory because of high contralateral involvement

— Klein's line: line drawn along the superior femoral neck on AP view should intersect the lateral epiphysis; in SCFE it fails to intersect the epiphysis (Trethowan sign)

— Steel's metaphyseal blanch sign: crescentic area of increased density at the metaphysis from overlap of displaced epiphysis

— Widening and irregularity of the physis (pre-slip or early slip)

— Loss of epiphyseal height on AP view

— Posterior displacement of the epiphysis best seen on frog-leg lateral

— Mild: <30°

— Moderate: 30–50°

— Severe: >50°

— TSH, free T4 (hypothyroidism)

— BMP, calcium, phosphorus, PTH, 25-OH vitamin D (renal osteodystrophy, rickets)

— IGF-1, morning cortisol, LH/FSH, testosterone/estradiol if pituitary suspected

Board pearl: A normal AP pelvis does not rule out SCFE — the slip is predominantly posterior, so the frog-leg or cross-table lateral is the most sensitive view. If the stem describes "normal AP x-ray" in an obese adolescent with hip/knee pain and limp, the next best step is lateral hip imaging, not reassurance and ibuprofen.

Imaging is the diagnosis — order BOTH views, BOTH hips:

Classic radiographic signs (memorize these — they are tested verbatim):

Slip severity grading (Southwick angle on lateral view):

Labs — only if endocrine SCFE suspected (atypical age, short stature, non-obese, bilateral):

No role for routine CBC/CRP/ESR unless septic arthritis is on the differential (then add joint aspiration before MRI)

Diagnostic Workup — Advanced or Confirmatory Studies

— Pre-slip suspected with normal or equivocal radiographs (widened physis, marrow edema, periphyseal edema on T2/STIR)

— Symptomatic adolescent with normal x-rays but persistent limp

— Pre-operative planning in complex/severe slips

— Evaluation for early avascular necrosis post-fixation

— Reserved for operative planning in severe or chronic slips when 3D anatomy of the deformity (cam impingement, retroversion) must be characterized

— Better than x-ray for physeal closure assessment in older adolescents

— Higher radiation — not first-line in pediatric workup

— Largely replaced by MRI; historical use in detecting AVN

— Limited utility for SCFE itself, but can detect a joint effusion and help differentiate from septic arthritis or transient synovitis in younger children

— Pituitary MRI if low IGF-1, low gonadotropins, or visual symptoms

— Renal ultrasound + nephrology referral for renal osteodystrophy picture

— DEXA if rickets or chronic steroid exposure

— Apply Kocher criteria (fever >38.5°C, non–weight-bearing, ESR >40, WBC >12k)

— Proceed to ultrasound-guided hip aspiration before MRI to avoid delay

— Baseline bilateral films at diagnosis; some centers obtain follow-up imaging every 3–4 months until physeal closure to detect silent slips

Step 3 management: If x-rays look normal but clinical suspicion is high (obese adolescent, limp, limited internal rotation, persistent pain >2 weeks), order MRI before sending the patient home. Missed pre-slip evolves into unstable SCFE with catastrophic AVN risk — and the documentation gap becomes the lawsuit.

MRI of the hip — most useful in the following scenarios:

CT scan:

Bone scan / SPECT:

Ultrasound:

Endocrine confirmatory studies when initial screening abnormal:

When septic arthritis cannot be excluded (febrile child with hip pain, elevated CRP/ESR):

Contralateral hip surveillance imaging:

Management Logic — From ED to OR

— Immediate strict non–weight-bearing, wheelchair transport, NPO

— Admit to pediatric orthopedics — outpatient management is never appropriate for an acute slip

— Pain control (acetaminophen + opioid as needed); avoid aggressive manipulation

— Stable SCFE: surgical fixation within 24–48 hours, semi-urgent

— Unstable SCFE: urgent surgical fixation, ideally within 24 hours of presentation (some advocate within 6–12 hours, though data are mixed); the longer the delay, the higher the AVN risk — but emergent overnight fixation is not clearly superior, so well-resourced daytime OR is acceptable

— In situ percutaneous screw fixation with a single cannulated screw across the physis — gold standard for stable and most unstable slips

— Goal: stabilize the slip, prevent progression, induce physeal closure — not to reduce the deformity

— May require modified Dunn procedure (subcapital realignment osteotomy with surgical hip dislocation) at experienced centers

— Higher reduction quality but historically higher AVN rate

— Endocrinopathy present

— Young age (<10 years, open triradiate cartilage)

— Obesity with high posterior sloping angle

— Poor follow-up reliability

CCS pearl: On a CCS-style case: order NPO, IV fluids, NWB with wheelchair, pediatric orthopedics consult STAT, type and screen, CBC/BMP, AP pelvis + bilateral frog-leg lateral. Do not order PT, do not order weight-bearing as tolerated, and do not discharge home pending outpatient ortho — those choices will tank the case.

The diagnosis is made → the patient does NOT walk again until fixed. This is non-negotiable.

Definitive treatment is surgical — there is no role for casting, traction, or conservative management for an actual SCFE

Timing by stability:

Procedure of choice:

Severe slips (Southwick >50°) or those with significant impingement:

Contralateral prophylactic fixation — controversial but increasingly favored when:

Surgical Fixation — Technique and Pharmacotherapy

— Single partially threaded cannulated screw placed under fluoroscopy from the anterolateral femoral neck, perpendicular to the physis, centered in the epiphysis on both AP and lateral views

— At least 5 threads across the physis for stable closure

— Screw tip ≥5 mm from subchondral bone to avoid joint penetration ("approach-withdraw" technique to confirm no breach)

— Single screw preferred for stable slips — minimizes AVN risk and physeal disruption

— Two screws sometimes used in unstable slips for rotational stability, but adds AVN risk

— Stable slips: NO reduction — fix in situ, accept deformity, address impingement later

— Unstable slips: gentle "serendipitous" reduction during positioning is acceptable; forceful reduction is contraindicated (kinks vessels → AVN)

— Cefazolin 30 mg/kg IV within 60 min of incision for surgical prophylaxis (clindamycin if PCN-allergic)

— Multimodal analgesia: acetaminophen + ibuprofen scheduled; opioids as rescue; avoid prolonged opioid scripts

— DVT prophylaxis: mechanical (SCDs) routinely; chemical only if additional risk factors (post-pubertal, obesity, OCP use, thrombophilia)

— Bowel regimen if opioids prescribed (docusate ± senna)

— Stable slip: toe-touch/partial WB with crutches for 4–6 weeks, then progress

— Unstable slip: strict NWB for 6–8 weeks

— Routine removal not recommended unless symptomatic; consider after physeal closure

Board pearl: In situ fixation is the answer in 90% of Step 3 stems. Closed or open reduction maneuvers, spica casting, traction, and physical therapy as first-line are all distractors. The screw stops progression — that is the entire surgical goal.

In situ percutaneous screw fixation — operative principles:

Single vs two screws:

Reduction debate:

Perioperative pharmacotherapy:

Post-op weight-bearing:

Implant removal:

Management of Severe Slips and Sequelae

— In situ fixation still indicated to halt progression, but the residual cam morphology causes femoroacetabular impingement (FAI) and early osteoarthritis

— Secondary procedures to consider after physeal closure:

— Imhäuser intertrochanteric osteotomy — corrects deformity distal to the slip, preserves blood supply

— Surgical hip dislocation with femoral neck osteoplasty for cam lesion

— Modified Dunn procedure for severe acute unstable slips at high-volume centers

— Early detection on MRI 3–6 months post-op

— Non-weight-bearing, bisphosphonate consideration, core decompression in select pre-collapse cases

— End-stage AVN in adolescents may require hip arthroscopy, osteotomy, or eventual total hip arthroplasty — life-altering in a teenager

— Acute cartilage loss with progressive stiffness and joint space narrowing

— Aggressive PT to maintain ROM, NSAIDs, intra-articular injections; rarely capsular release

— Treat underlying endocrinopathy concurrently — levothyroxine for hypothyroidism, GH adjustment, optimize renal osteodystrophy (phosphate binders, calcitriol, dialysis adequacy)

— Recurrence and contralateral slip rates are much higher — prophylactic contralateral pinning is standard in endocrine SCFE

— NSAIDs first-line; intra-articular corticosteroid injection for impingement-related pain bridges to definitive procedure

Step 3 management: When an obese 9-year-old presents with bilateral SCFE, the next step after fixation is endocrine workup (TSH, free T4, IGF-1, BMP) — not reassurance. Bilateral SCFE in an atypical-age patient is endocrinopathy until proven otherwise, and missing it leads to recurrent slips and growth plate complications.

Severe/chronic slips and residual deformity:

Avascular necrosis management:

Chondrolysis management:

Endocrine SCFE treatment integration:

Pain control longitudinally:

Special Populations — Renal Osteodystrophy and Adolescents on Dialysis

— Children on dialysis or with stage 4–5 CKD develop renal osteodystrophy with secondary hyperparathyroidism, hyperphosphatemia, vitamin D deficiency, and physeal weakness

— These slips are often bilateral, atypical age, and recurrent

— Slip may occur through a widened, disorganized growth plate even without obesity

— BMP (BUN/Cr), calcium, phosphorus, PTH, alkaline phosphatase, 25-OH vitamin D, 1,25-OH vitamin D

— Bone age x-ray (often delayed)

— Nephrology co-management mandatory

— Phosphate binders (calcium acetate, sevelamer) to lower serum phosphorus

— Active vitamin D analogs (calcitriol, paricalcitol) to suppress PTH

— Calcimimetics (cinacalcet) for severe secondary hyperparathyroidism

— Dialysis adequacy review (Kt/V); pre-op dialysis day before surgery typically

— Avoid nephrotoxic perioperative drugs (NSAIDs, aminoglycosides, contrast)

— Higher infection and wound complication risk

— Bilateral prophylactic fixation routinely recommended given near-universal bilaterality

— Anesthesia coordination for fluid/electrolyte status; review K+ and bicarbonate pre-op

— Rarely primary driver of SCFE, but adjust acetaminophen dose and avoid hepatotoxic adjuncts

— If considering bisphosphonates for AVN, dose adjust based on creatinine clearance, not LFTs

Board pearl: A short-statured adolescent on hemodialysis presenting with bilateral hip/knee pain has renal osteodystrophy–associated SCFE — obtain x-rays of both hips, check PTH and phosphate, and consult ortho and nephrology. Do not treat with NSAIDs; do not delay surgical stabilization waiting for "medical optimization" beyond essentials.

SCFE in chronic kidney disease (CKD) — a Step 3 favorite buzz-pattern:

Workup additions in suspected CKD-SCFE:

Medical optimization before/around surgery:

Surgical considerations:

Hepatic impairment:

Special Populations — Pediatric Age Extremes and Endocrine Subtypes

— Boys <10 or girls <8 or any child with slip after typical physeal closure age (boys >16, girls >14) → mandatory endocrine workup

— Height <10th percentile or weight <50th percentile with SCFE is also a red flag (typical SCFE patient is overweight)

— Check TSH and free T4; treat with levothyroxine before or concurrent with surgery

— Bilateral slips and physeal widening prominent

— Both GH deficiency and exogenous GH replacement increase SCFE risk

— In a child on GH therapy who develops hip/knee pain, stop GH temporarily, image, and consult orthopedics

— GH can typically be resumed after fixation

— Often present with delayed puberty and short stature; check LH, FSH, testosterone/estradiol, IGF-1, morning cortisol

— Pelvic radiation for childhood malignancy disrupts physeal integrity; surveillance hip imaging during adolescence is reasonable

— Generalized ligamentous laxity; slips can occur at atypical ages with subtle presentations

— Endocrinopathy (any)

— Age <10 years

— Open triradiate cartilage

— Significant posterior sloping angle (>14°)

— Poor follow-up reliability

Key distinction: A typical SCFE patient is an obese 12-year-old — endocrine workup is not mandatory. An atypical SCFE patient (thin, short, very young, very old, or bilateral) demands a full endocrine evaluation and almost always prophylactic contralateral fixation. This binary drives the workup question on the exam.

Atypical-age SCFE — the "look for endocrine disease" patient:

Hypothyroidism — most common endocrinopathy associated with SCFE:

Growth hormone deficiency / GH therapy:

Panhypopituitarism, hypogonadism, growth-hormone–related disorders:

Prior radiation exposure:

Down syndrome and other syndromic associations:

Pregnancy: not applicable — SCFE is a pre-pubertal/peripubertal entity; pregnancy in this age group is uncommon and not directly relevant to SCFE pathophysiology

Contralateral prophylactic pinning indications (memorize):

Complications and Adverse Outcomes

— Risk: ~20–50% in unstable slips, <10% in stable slips, near 0% with proper in situ fixation of stable slips

— Caused by disruption of the medial femoral circumflex artery / posterior superior retinacular vessels at the time of slip or during forceful reduction

— Presents 3–12 months post-op with worsening pain, stiffness, and limp; MRI confirms

— Leads to femoral head collapse, secondary OA, and potential total hip arthroplasty in adolescence

— Rapid loss of articular cartilage with global joint space narrowing on x-ray

— Risk factors: screw penetration into the joint, severe slip, prolonged immobilization, persistent pin protrusion

— Presents with stiffness and pain; treat with PT, NSAIDs, occasionally capsulotomy

— Largely preventable with meticulous intra-op fluoroscopy and "approach-withdraw" technique

— Residual cam deformity from healed slip causes anterior impingement, labral tears, and early hip osteoarthritis by 30s–40s

— May warrant later osteochondroplasty or osteotomy

— Rare with proper screw placement (≥5 threads across physis); higher if implant fails or growth continues without physeal closure

— Up to 50% within 18–24 months — counseling and surveillance critical

— Hardware prominence, irritation; rarely fracture through screw track

— Subtrochanteric stress fracture if entry point too distal

Board pearl: AVN risk is determined at the moment of the slip, not at the moment of fixation — but forceful closed reduction of an unstable slip can convert a salvageable hip into a doomed one. The answer to "how can we prevent AVN" is in situ fixation without aggressive manipulation, not "spica cast" or "traction."

Avascular necrosis (AVN) of the femoral head — the most feared complication:

Chondrolysis (acute cartilage necrosis):

Femoroacetabular impingement (FAI) and early OA:

Slip progression after fixation:

Contralateral slip:

Implant-related issues:

General surgical risks: infection, DVT (low in this age group), anesthetic complications, blood loss (usually minimal)

When to Escalate Care — Admission, Consults, Transfer

— No outpatient management is appropriate; "follow up in clinic Monday" is a wrong-answer trap

— Unstable slip (cannot bear weight) → urgent OR within 24 hours; if no pediatric ortho available, transfer to a tertiary pediatric center via stretcher transport, NWB, with adequate analgesia

— Suspected neurovascular compromise (rare, but cool/dusky limb, absent pulses) → emergent

— Severe slip (Southwick >50°) especially unstable → consider transfer to a center experienced in modified Dunn procedure

— Bilateral simultaneous unstable slips → tertiary pediatric ortho

— Underlying endocrinopathy or CKD on dialysis → multidisciplinary care

— Pediatric orthopedic surgery (primary)

— Pediatrics or pediatric hospitalist for medical co-management, especially if obesity-related comorbidities (OSA, T2DM, hypertension)

— Anesthesia for pre-op evaluation — obese adolescents often need airway planning and OSA screening

— Endocrinology if atypical age or bilateral

— Nephrology if CKD-related

— Social work / case management for transportation, school accommodations, follow-up logistics

— Tolerating diet, pain controlled on PO regimen, ambulating safely with crutches (or wheelchair if unstable slip with NWB), clear understanding of weight-bearing restrictions, follow-up arranged within 1–2 weeks

CCS pearl: A 13-year-old obese boy who cannot bear weight with a positive Klein's line — the orders that score points: admit to peds ortho, NPO, IV fluids, NWB, pain control, type and screen, consult pediatric orthopedic surgery STAT, OR within 24 hours.

Every confirmed or strongly suspected SCFE = inpatient admission to a facility with pediatric orthopedic surgery

Immediate escalation triggers:

Consultations to place on admission:

Discharge criteria after fixation:

Do NOT discharge from ED with crutches and orthopedic referral — this is a frequent wrong-answer distractor that has been associated with delays leading to slip progression and litigation

Key Differentials — Hip/Musculoskeletal Causes

— Idiopathic AVN of femoral head in younger children (ages 4–8, peak 5–7), more often thin, active boys

— Insidious limp, hip/knee pain, decreased internal rotation and abduction

— X-ray: crescent sign, femoral head sclerosis/fragmentation

— Key distinction: age and body habitus — LCPD = small 6-year-old; SCFE = chubby 12-year-old

— Infant/toddler presentation, asymmetric thigh folds, positive Ortolani/Barlow in newborn, painless limp in older child

— Not in the SCFE age range typically

— Ages 3–8, post-viral, atraumatic hip pain with limp, afebrile or low-grade fever, normal/mildly elevated inflammatory markers

— Self-limited, treat with NSAIDs and rest; resolves in 1–2 weeks

— High fever, refusal to bear weight, elevated WBC/ESR/CRP (Kocher criteria)

— Surgical emergency — joint aspiration confirms; OR drainage required

— Can coexist with SCFE workup confusion when febrile obese teen presents — aspirate hip if any doubt

— Adolescent runner/athlete, gradual onset groin pain worse with activity

— X-ray often normal early; MRI diagnostic

— High risk of progression to displaced fracture — non–weight-bearing

— Athletes with hip/pelvic pain at apophyseal sites; rest and PT

— High-energy mechanism distinguishes from SCFE's typically low/no trauma

— Often in older adolescents/young adults, mechanical symptoms (clicking, catching), positive impingement tests

Key distinction: Age + body habitus + lateral x-ray view will sort 95% of these on the boards. Limp + obese + 12yo + reduced IR = SCFE; limp + skinny + 6yo + reduced IR/abduction = Perthes; limp + fever + can't move hip + 5yo = septic arthritis.

Legg-Calvé-Perthes disease (LCPD):

Developmental dysplasia of the hip (DDH):

Transient (toxic) synovitis:

Septic arthritis of the hip:

Stress fracture of femoral neck:

Apophysitis (iliac crest, ASIS, ischial):

Acute traumatic fracture (femoral neck, intertrochanteric):

Hip labral tear / FAI:

Key Differentials — Non-Orthopedic and Referred Causes

— SCFE can present with isolated medial knee or distal thigh pain via obturator nerve referral

— Up to 15–50% of SCFE patients have knee pain as the only or chief complaint

— Every adolescent with knee pain and a limp gets a hip exam and hip x-rays if exam is suspicious — failing to do so is a recurring board theme and a documented malpractice scenario

— Appendicitis (right-sided, with psoas sign) — fever, RLQ tenderness, GI symptoms

— Inguinal hernia, testicular torsion, ovarian torsion — examine GU thoroughly

— Iliopsoas abscess — fever, hip flexion contracture, immunocompromised host

— Inflammatory bowel disease–related arthritis in adolescents with GI symptoms

— Osteosarcoma of distal femur or proximal tibia — knee pain, palpable mass, night pain, x-ray with sunburst periosteal reaction

— Ewing sarcoma of femur/pelvis — systemic symptoms, onion-skinning on x-ray

— Leukemia — diffuse bone pain, fatigue, pallor, abnormal CBC

— Any "growing pains" persisting >2 weeks with focal tenderness or night pain warrants imaging and CBC

— Juvenile idiopathic arthritis — multiple joints, morning stiffness, elevated inflammatory markers

— Reactive arthritis — post-infectious (GI/GU)

— SLE, ankylosing spondylitis (HLA-B27), psoriatic arthritis — pattern recognition

— Sickle cell disease — vaso-occlusive crisis or AVN of femoral head; check hemoglobin electrophoresis history

— Hemophilia — hemarthrosis

Board pearl: When the stem describes an obese adolescent with "knee pain for 6 weeks, normal knee exam, normal knee x-ray", the next step is AP pelvis and frog-leg lateral hip x-ray — not knee MRI, not orthopedic referral for knee. This is one of the most consistently tested patterns in pediatric Step 3 musculoskeletal questions.

Referred knee pain — the SCFE pitfall to know cold:

Pelvic and intra-abdominal causes mimicking hip pain:

Tumors — rare but devastating misses:

Rheumatologic causes:

Hematologic:

Secondary Prevention and Long-Term Plan

— Bilateral hip x-rays (AP + frog-leg lateral) at every follow-up until physeal closure (typically age 15–16 in girls, 16–18 in boys)

— Counsel patient and family on signs of contralateral slip — any new hip/knee/thigh pain or limp warrants urgent re-evaluation

— Endocrinopathy of any kind

— Age <10 years at index slip

— Open triradiate cartilage

— Posterior sloping angle >14°

— Unreliable follow-up

— Address obesity directly: nutrition counseling, structured physical activity (low-impact: swimming, cycling once cleared), behavioral support, family-based interventions

— Screen and treat OSA, T2DM, NAFLD, dyslipidemia, hypertension — these adolescents have high cardiometabolic burden

— Consider referral to a pediatric obesity/weight management program

— Bariatric surgery consideration in select severe cases (per AAP 2023 guidelines, BMI ≥35 with comorbidities or ≥40)

— Continue thyroid hormone replacement, GH therapy adjustments, CKD bone mineral metabolism management, hypogonadism replacement as indicated

— Monitor for FAI symptoms and early OA; consider osteochondroplasty or osteotomy if symptomatic deformity

— Avoid high-impact athletics for at least 6 months post-fixation; gradual return to sport with surgeon clearance

— Catch up on routine pediatric care including HPV, Tdap, meningococcal; flu annually

— Mental health screening — chronic pain and obesity have high overlap with depression and anxiety

Step 3 management: Discharge planning includes structured follow-up at 2 weeks, 6 weeks, 3 months, 6 months, and then every 6 months until skeletal maturity with bilateral hip imaging at each visit. Weight management referral and endocrine workup (if not already done) are part of the long-term plan — orthopedic fixation alone is not "treatment complete."

Contralateral hip surveillance — non-negotiable:

Prophylactic contralateral fixation indications (revisit):

Weight management — the cornerstone of secondary prevention:

Endocrine optimization:

Long-term joint preservation:

Immunizations and general pediatric care:

Follow-Up, Monitoring, and Rehabilitation

— 2 weeks: wound check, suture removal if non-absorbable, x-ray to confirm screw position

— 6 weeks: x-ray, advance weight-bearing in stable slips, begin PT (gentle ROM, gradual strengthening)

— 3 months: assess physeal closure progression, return-to-school/light activity counseling

— 6 months: evaluate for AVN signs (pain, stiffness, MRI if suspicion), screw position, contralateral hip surveillance

— Every 6 months until skeletal maturity (usually 18–24 months total), then transition to adult ortho if persistent deformity

— Bilateral AP pelvis + frog-leg lateral until both physes are closed

— MRI only if symptoms suggest AVN, chondrolysis, or FAI

— Stable slip: toe-touch with crutches × 4–6 weeks → partial WB → full WB by 8–12 weeks

— Unstable slip: strict NWB × 6–8 weeks → gradual progression over 12 weeks with ortho clearance

— Begin gentle ROM after initial healing; progress to hip abductor and core strengthening

— Aquatic therapy useful in obese adolescents — low joint load

— Avoid forceful manipulation, end-range stretching that could disrupt fixation

— Earliest at 3–6 months for stable slips with confirmed physeal closure and no residual deformity

— Avoid contact and high-impact sports until full strength, no pain, normal gait

— Unstable slips with AVN risk may have indefinite restrictions

— Recognize symptoms of contralateral slip and AVN

— Importance of completing follow-up despite feeling well

— Lifelong joint preservation strategies (weight, low-impact activity)

— Long-term arthritis risk — set realistic expectations

Board pearl: AVN can present up to 2 years after fixation — a teenager with worsening hip pain 18 months post-op warrants MRI of the hip, not reassurance. Do not assume a "healed" slip is the end of the story; the surveillance window is long.

Typical follow-up cadence after fixation:

Imaging at each visit:

Weight-bearing progression:

Physical therapy:

Return to sport:

Counseling content:

Ethical, Legal, and Patient Safety Considerations

— Failure to examine and image the hip in an adolescent with knee/thigh pain is a leading source of pediatric orthopedic litigation

— Document hip exam (ROM, Drehmann), gait, and rationale for or against hip imaging in every adolescent limp/knee-pain encounter

— Closing the loop: if x-rays are deferred, document follow-up plan and red-flag return precautions

— Consent from parents/legal guardians for surgery in minors; assent from the adolescent (typically age ≥7, certainly by 12–14) is ethically required and increasingly standard

— Explicitly discuss: AVN risk (10–50% depending on stability), chondrolysis, FAI, contralateral slip risk, need for prophylactic pinning if applicable, hardware issues, possibility of subsequent osteotomy or arthroplasty

— Document AVN risk discussion separately for unstable slips — courts have specifically focused on whether families understood this

— SCFE is not abuse-related, but evaluate for neglect when delay in care is profound (months of limp without medical attention), especially in vulnerable populations; report to CPS per state law if concern

— Differentiate medical neglect from socioeconomic access barriers — engage social work before reporting

— ED-to-ortho handoff: explicit communication of NWB status, timing of OR, NPO status; never discharge to ortho clinic on the wrong day

— Hospital-to-home transition: crutches/wheelchair training, written WB instructions, school accommodations letter, follow-up appointment scheduled before discharge

— Pediatric-to-adult care transition at skeletal maturity if residual deformity persists

— Disproportionate SCFE burden in African American, Hispanic, and Pacific Islander adolescents and in lower-income communities; ensure follow-up logistics and transportation are addressed

— Insurance authorization for prophylactic contralateral pinning may require advocacy

Step 3 management: Never discharge an adolescent with suspected SCFE on crutches with outpatient follow-up — admission for fixation is the standard of care, and deviation must be explicitly justified. Document non–weight-bearing instructions in writing and confirm caregiver understanding.

Missed knee-pain SCFE — the malpractice classic:

Informed consent — pediatric-specific issues:

Mandatory reporting considerations:

Transition-of-care safety:

Health systems and equity:

High-Yield Associations and Rapid-Fire Clinical Facts

Key distinction: Stable SCFE is urgent; unstable SCFE is emergent. Stability is defined by ability to bear weight at presentation — not by symptom duration, x-ray displacement, or pain severity. This single dichotomy organizes the entire management algorithm and almost every Step 3 question.

Demographics: obese adolescent boy, 12–14 years, African American or Pacific Islander, peripubertal

Bilateral in 20–40%; up to 50% develop contralateral slip within 18–24 months

Loder stable (can bear weight) vs unstable (cannot) — drives AVN risk and urgency

AVN risk: stable <10%, unstable 20–50%

Klein's line fails to intersect the lateral epiphysis (Trethowan sign)

Frog-leg lateral is the most sensitive single view

Steel's metaphyseal blanch sign on AP view

Southwick angle grades severity: <30° mild, 30–50° moderate, >50° severe

Drehmann sign: obligatory external rotation with hip flexion

In situ percutaneous single cannulated screw fixation = gold standard

No closed reduction in stable slips; no forceful reduction in unstable slips

At least 5 screw threads across the physis; tip 5 mm from subchondral bone

Modified Dunn procedure: severe acute slips at tertiary centers

Endocrine workup (TSH, free T4, BMP, IGF-1, PTH) if atypical age, short stature, non-obese, or bilateral

Most common endocrine association: hypothyroidism; also GH deficiency/therapy, renal osteodystrophy, panhypopituitarism, prior pelvic radiation

Knee/thigh pain via obturator nerve referral in 15–50% — always examine the hip in adolescent knee pain

Prophylactic contralateral pinning: endocrinopathy, age <10, open triradiate, posterior sloping angle >14°, unreliable follow-up

Chondrolysis: avoid intra-articular screw penetration (approach-withdraw technique)

Adolescent FAI and early hip OA are long-term sequelae — even after "successful" fixation

CCS triage: admit, NPO, NWB, IV fluids, pain control, peds ortho consult, type and screen, OR within 24 hours for unstable

Differential: Perthes (younger, thin), septic arthritis (febrile, refuses motion), transient synovitis (post-viral), stress fracture (athlete), tumor (night pain, mass)

Board Question Stem Patterns

— "A 13-year-old obese boy presents with 6 weeks of left thigh and knee pain and an antalgic limp. Exam reveals decreased internal rotation; with hip flexion, the leg externally rotates. He can bear weight with discomfort." → Diagnosis: stable SCFE; next step: AP pelvis + bilateral frog-leg lateral x-rays; management: admission, NWB, in situ screw fixation

— "12-year-old with isolated medial knee pain for 1 month; knee exam and x-ray normal." → Next step: hip x-rays (AP pelvis + frog-leg lateral)

— "14-year-old obese boy, sudden inability to bear weight after minor twist; leg externally rotated." → Urgent in situ fixation within 24 hours; do not attempt closed reduction; counsel on 20–50% AVN risk

— "9-year-old short-statured girl with bilateral hip pain and limp; weight at 25th percentile." → Bilateral SCFE; check TSH, free T4, IGF-1, BMP; in situ fixation of affected hip plus prophylactic contralateral pinning; treat underlying endocrinopathy

— "13-year-old on hemodialysis with bilateral knee/thigh pain." → Bilateral SCFE; obtain PTH, phosphate, calcium; bilateral fixation; nephrology co-management

— "6-year-old thin boy with painless limp and limited abduction." → Legg-Calvé-Perthes, not SCFE

— "4-year-old with fever 39°C, refuses to bear weight, elevated CRP." → Septic arthritis — joint aspiration

— "14-year-old 8 months post in situ fixation with worsening hip pain and stiffness." → AVN — order MRI of the hip

— Outpatient orthopedic follow-up with crutches → wrong

— Closed reduction in the ED → wrong

— Spica casting / traction → wrong

— Knee MRI as next step in adolescent knee pain with limp → wrong

— Discharge home after "negative" AP pelvis without lateral view → wrong

Board pearl: When you see an obese 12–14-year-old with limp + hip/knee/thigh pain + decreased internal rotation, the answer is hip x-rays followed by admission and in situ screw fixation — full stop. Memorize this reflex.

Pattern 1 — Classic stable SCFE:

Pattern 2 — Knee-pain misdirection:

Pattern 3 — Unstable SCFE:

Pattern 4 — Endocrine SCFE:

Pattern 5 — Renal osteodystrophy:

Pattern 6 — Differential discrimination:

Pattern 7 — Complication recognition:

Pattern 8 — Wrong-answer traps to avoid:

One-Line Recap

SCFE is a Salter-Harris I fracture through the proximal femoral physis in an obese peripubertal adolescent — diagnosed by bilateral AP pelvis and frog-leg lateral x-rays (Klein's line), classified by ability to bear weight (stable vs unstable), treated with urgent in situ percutaneous single-screw fixation, and complicated chiefly by avascular necrosis whose risk is determined at the moment of the slip and worsened by forceful reduction.

Step 3 management: The single highest-yield reflex on the boards — adolescent with knee pain and a limp gets a hip exam and hip x-rays; missing SCFE because you only looked at the knee is the prototypical pediatric orthopedic error and a perennial test favorite.

Diagnosis reflex: obese 12–14-year-old with limp and hip/thigh/knee pain + reduced internal rotation + positive Drehmann sign → AP pelvis + bilateral frog-leg lateral (most sensitive view) → look for Klein's line failure and Steel's blanch sign

Management reflex: admit, NPO, strict non–weight-bearing, pediatric orthopedic consult, in situ percutaneous single cannulated screw fixation — within 24–48 hours for stable, within 24 hours for unstable; never forceful closed reduction; consider prophylactic contralateral pinning if endocrinopathy, age <10, open triradiate, or unreliable follow-up

Endocrine reflex: atypical age (<10 or >16), short stature, non-obese, or bilateral SCFE → check TSH, free T4, IGF-1, BMP, PTH — hypothyroidism, GH deficiency/therapy, panhypopituitarism, renal osteodystrophy, prior pelvic radiation

Long-term reflex: surveillance bilateral hip x-rays every visit until skeletal maturity, monitor for AVN (up to 2 years post-op), chondrolysis, FAI, and early hip osteoarthritis; address obesity and cardiometabolic comorbidities as core secondary prevention