Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Slipped upper femoral epiphysis
Musculoskeletal medicine and orthopaedics · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Time-critical presentation
Any suspected SUFE requires immediate strict non-weight-bearing, analgesia and same-day paediatric orthopaedic discussion. Do not ask the child to walk, perform repeated range testing or attempt reduction. An unstable slip in a child unable to bear weight has a high femoral-head osteonecrosis risk and needs urgent specialist handling. Use an AP pelvis plus a gentle cross-table lateral when instability is possible; a forced frog-leg view can worsen displacement.
Overview
Recognise an adolescent proximal-femoral physeal slip from hip or referred knee symptoms, stop further displacement immediately and coordinate urgent in-situ stabilisation and contralateral surveillance.
Ask about the first pain site and duration, limp, sports, minor trauma and whether weight bearing remains possible. SUFE can refer entirely to the knee because of obturator and femoral nerve pathways. Clarify acute onset on a background of weeks of intermittent symptoms. Record puberty, growth, weight trajectory, endocrine symptoms, kidney disease, radiotherapy and hormone treatment. Ask explicitly about the opposite hip and establish ability to use crutches before allowing any transfer.
Observe resting foot progression and leg length from bed. Gently assess log roll and hip flexion only until pain or obligatory external rotation appears; do not force internal rotation. Examine the knee, abdomen and spine to avoid anchoring, but a normal knee in an adolescent with limp increases rather than reduces the need for hip assessment. Document distal neurovascular findings. Classify stability from pre-presentation weight-bearing history, not by making the child stand in clinic.
Practice
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Musculoskeletal medicine and orthopaedicsOriginal SBA
Adolescent with knee pain
An obese 13-year-old has several weeks of knee pain, an out-toed limp and obligatory external rotation when the hip is flexed. What is the next best action?
Sources and review status3 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Obtain bilateral AP pelvis and lateral imaging. A stable child can usually undergo careful frog-leg laterals; an unstable painful hip should not be abducted and externally rotated, so use a cross-table lateral under radiographic and orthopaedic guidance. Look for physeal widening and irregularity, reduced epiphyseal height, metaphyseal blanch sign and failure of Klein line to intersect the epiphysis. Measure slip angle for severity and compare both sides.
Very early pre-slip change can be radiographically subtle. MRI shows physeal widening, oedema and effusion when clinical suspicion remains high, but it must not permit walking or delay urgent specialist review. Ultrasound may show effusion and step but is not the reference exclusion test. CT adds radiation and is reserved for complex deformity or surgical planning. Blood tests do not diagnose a typical SUFE; choose endocrine and renal tests for atypical presentation.
Protect the physis from the first suspicion. Keep the child in bed or use a wheelchair, prohibit weight bearing and give age-appropriate analgesia. Transfer to the treating service without repeated examinations. Routine skin traction does not fix the slip. Do not attempt closed reduction in the emergency department because vascular kinking or tearing can convert a treatable slip into femoral-head osteonecrosis.
Stable slips are usually fixed percutaneously with one screw across the physis in the position found. The goal is to prevent progression while minimising joint penetration and vascular injury, not to normalise the radiograph immediately. Confirm screw position in two planes and avoid placing the tip into the joint. The physis then closes. Severe stable deformity can later undergo specialist osteochondroplasty or realignment when impingement risk justifies additional morbidity.
Unstable SUFE needs urgent senior management. The team controls positioning, considers capsular decompression and decides whether gentle reduction, in-situ fixation or an open modified Dunn-type realignment is appropriate to experience and anatomy. These operations carry different osteonecrosis and deformity risks and should not be improvised. Treat acute-on-chronic disease by protecting the current unstable component while recognising the established cam deformity.
Assess the opposite hip at every visit. Prophylactic fixation is considered when endocrine or renal disease, very young age, unreliable follow-up or radiographic risk creates a high probability and the family accepts operative harm. Otherwise provide rapid-access advice for contralateral pain and continue clinical and radiographic surveillance to physeal closure. Long-term follow-up checks osteonecrosis, chondrolysis, screw position, head-neck shape, impingement, leg length and return to activity.
Key points
SUFE usually affects an adolescent and may present as isolated thigh or knee pain; always examine both hips when the knee findings do not explain the limp.
The affected leg rests externally rotated and hip flexion produces obligatory external rotation with loss of internal rotation.
Stable means the child can bear weight with or without crutches; unstable means they cannot, and the osteonecrosis risk is substantially higher.
First-line imaging is bilateral AP pelvis plus frog-leg lateral views for a clearly stable slip; use a cross-table lateral rather than forced frog-leg positioning when unstable.
Immediately make every suspected case non-weight-bearing and obtain same-day orthopaedic review; never ask the child to walk for diagnostic confirmation.
First-line definitive treatment for most stable slips is percutaneous single-screw fixation in situ without intentional reduction.
Unstable or severe slips require senior paediatric-hip planning; capsular decompression and any gentle reduction or open realignment are specialist decisions.
Investigate atypical age or habitus for endocrine or renal disease and monitor the opposite hip until physeal closure.
Aetiology
01
Adolescent physeal vulnerability
The proximal femoral physis becomes oblique and mechanically weaker during the pubertal growth spurt before eventual closure.
02
Obesity and shear load
Higher body mass increases shear across the sloping physis and is the most common modifiable association in otherwise typical presentations.
03
Endocrine and renal disease
Hypothyroidism, growth-hormone disturbance, hypogonadism and renal osteodystrophy alter physeal strength and can cause atypical age or body habitus.
04
Anatomical predisposition
Femoral and acetabular version, physeal orientation and prior radiotherapy can concentrate posterior-inferior shear at the growth plate.
Pathophysiology
1
Physeal shear failure
The metaphysis moves anteriorly and externally relative to the epiphysis, while the femoral head remains located within the acetabulum.
2
Progressive displacement
Continued walking increases posterior-inferior slip, deforming the head-neck junction and narrowing the remaining stable physeal contact.
3
Retinacular vessel injury
Unstable displacement and forceful reduction can disrupt femoral-head blood supply, leading to devastating secondary osteonecrosis and collapse.
4
Cam impingement
Residual metaphyseal prominence abuts the acetabular rim during flexion and internal rotation, damaging labrum and cartilage over time.
5
Contralateral susceptibility
The same growth, endocrine and mechanical environment affects both physes, so the opposite hip remains at risk until closure.
Clinical features and red flags
Referred knee pain
An adolescent can have a normal knee examination while proximal-femoral physeal pain is perceived entirely around the thigh or knee.
Obligatory external rotation
The leg turns outward as the hip flexes because the metaphysis impinges and internal rotation is mechanically lost.
Out-toed antalgic gait
External foot progression and shortened stance reduce painful hip motion in a stable child who can still walk.
Unstable weight-bearing loss
Inability to bear weight even with crutches identifies the high-risk unstable category without requiring provocative testing.
Widened irregular physis
Early radiographs show growth-plate widening and loss of smoothness before major posterior displacement becomes obvious.
Atypical endocrine phenotype
Very young or older age, short stature or low weight prompts thyroid, growth, gonadal and renal-bone assessment.
Red flags requiring action
An adolescent with hip, groin, thigh or unexplained knee pain and an out-turned foot has SUFE until adequate bilateral hip imaging excludes it.
Loss of weight-bearing ability, even with crutches, defines an unstable presentation and markedly increases osteonecrosis risk.
Obligatory external rotation as the hip flexes is a high-yield sign and should stop further provocative examination.
Investigations
01First-line bilateral AP pelvis radiographFirst stepFirst line
Why
Identify physeal widening, epiphyseal displacement, asymmetry and contralateral disease.
Interpretation and limitations
Klein line, epiphyseal height and metaphyseal signs support diagnosis, but subtle early disease can remain occult.
02Stability-appropriate lateral radiograph
Why
Demonstrate posterior displacement and measure slip severity without worsening the injury.
Interpretation and limitations
Use frog-leg lateral only for a stable comfortable hip; cross-table lateral is safer when weight bearing is impossible or instability is suspected.
03MRI for suspected pre-slip
Why
Detect physeal oedema, widening and early instability when radiographs are non-diagnostic.
Interpretation and limitations
MRI is the reference sensitive study for pre-slip change but should occur under strict non-weight-bearing and urgent specialist oversight.
04Endocrine and renal profile
Why
Find hypothyroidism, growth-axis disease, hypogonadism or renal osteodystrophy in an atypical case.
Interpretation and limitations
Select TSH, free T4, renal and mineral tests and further hormones from age, growth and examination; typical obesity alone does not require indiscriminate panels.
Differential diagnosis
01
Septic arthritis
Fever, systemic illness, severe pain through all movement and inflammatory response requires emergency aspiration and washout assessment.
02
Perthes disease
A younger child with gradual limp and femoral-head sclerosis or fragmentation has osteonecrosis of the capital epiphysis rather than physeal displacement.
03
Transient synovitis
A well younger child after viral illness may have short-lived painful restriction, but adolescent knee pain and out-toeing still demand hip radiographs.
04
Femoral-neck stress injury
Load-related groin pain in a highly active or low-bone-density adolescent can be radiographically occult and requires MRI with loading protection.
05
Knee pathology
Local knee tenderness or effusion can coexist, but a normal knee does not justify discharge before examining and imaging the hip.
Management
01SuspectedStop further slip immediatelyFirst stepAn adolescent has compatible hip, thigh or knee pain, external rotation or limited internal rotation.+
1Make the child strictly non-weight-bearing and use bed, trolley or wheelchair transfer.
2Give age- and weight-appropriate analgesia and document hip, knee and distal neurovascular findings without forceful motion.
3Obtain bilateral AP and stability-appropriate lateral radiographs and contact paediatric orthopaedics the same day.
4Use MRI for persistent pre-slip suspicion while maintaining protection; do not trial walking after normal films.
02Stable slipFix the physis in situImaging confirms a slip and the child could bear weight with or without crutches before assessment.+
1Maintain non-weight-bearing until surgery and classify chronicity, severity and contralateral findings.
Complications
01
Femoral-head osteonecrosis
Vascular disruption causes head collapse, pain and early arthritis and is especially associated with unstable slips and forceful manipulation.
02
Chondrolysis
Rapid articular cartilage loss produces severe stiffness and joint-space narrowing and can follow severe disease or intra-articular implant penetration.
03
Femoroacetabular impingement
Residual head-neck deformity abrades labrum and cartilage, causing reduced flexion, positive impingement testing and early osteoarthritis.
04
Slip progression
Delayed diagnosis or inadequate fixation permits further displacement, worsening proximal-femoral deformity and compromising later corrective options.
05
Contralateral SUFE
A later opposite slip can occur during remaining growth, requiring surveillance, family education and selective prophylactic fixation.
Monitoring and follow-up
Before fixation, maintain visible non-weight-bearing instructions and reassess for sudden pain or loss of limb position.
After surgery, inspect wound and neurovascular status and verify the child and carers understand loading restrictions.
Review radiographs for screw position, slip progression, physeal closure, osteonecrosis and chondrolysis.
Examine hip range, leg length, gait and later impingement symptoms without forcing motion early.
Ask about opposite hip, thigh or knee pain at every contact until both physes close.
Complete endocrine or renal referral and treatment when atypical presentation reveals a systemic driver.
Special situations
The knee can be innocent
Referred pain makes hip examination mandatory when adolescent knee findings do not explain the severity or limp.
Stability is historical
Classify from the child's ability to bear weight before examination, never by making an at-risk physis take another step.
The epiphysis stays seated
Radiographically the metaphysis appears to move while the femoral head remains within the acetabulum.
Reduction can harm perfusion
Forceful correction tensions retinacular vessels and can cause a worse outcome than accepting deformity during safe fixation.
A screw prevents progression
In-situ fixation stabilises the physis; it does not immediately remove established head-neck prominence or impingement.
The other hip remains vulnerable
Shared growth and endocrine factors persist, making clear contralateral safety-netting as important as postoperative wound advice.
Common pitfalls
01
Treating isolated knee pain without examining hip rotation in an adolescent.
02
Allowing a suspected SUFE to walk to radiology or to demonstrate the gait.
03
Forcing frog-leg positioning in an unstable painful slip.
04
Attempting emergency-department reduction or traction instead of in-situ protection and specialist planning.
05
Calling a subtle AP radiograph normal without an appropriate lateral or MRI when suspicion persists.
06
Discharging after unilateral fixation without contralateral surveillance and endocrine assessment when atypical.
Acute pain after weeks or months of limp suggests an acute-on-chronic slip that can progress suddenly.
Presentation before age ten, after sixteen, with short stature or low body weight warrants endocrine or renal-bone investigation.
Persistent or new pain in the opposite hip requires immediate reassessment because bilateral disease is common.
05
Post-fixation fluoroscopic radiographs
Why
Confirm screw crosses the physis centrally enough for stability without penetrating the joint.
Interpretation and limitations
Review AP and lateral trajectories and monitor later migration relative to growth and physeal closure.
2Perform percutaneous single-screw in-situ fixation without intentional forceful reduction in the standard stable case.
3Confirm extra-articular screw position in multiple planes and give explicit postoperative loading instructions.
4Follow physeal closure, head-neck shape, chondrolysis, osteonecrosis and contralateral symptoms.
03Unstable slipProtect femoral-head perfusionThe child cannot bear weight even using crutches or has sudden deterioration in an acute-on-chronic slip.+
1Avoid frog-leg positioning and all non-specialist manipulation and transfer with the limb supported.
2DefinitiveEscalationEscalate urgently to a senior paediatric hip surgeon and complete safe imaging without delaying definitive care.
3Let the specialist team decide decompression, gentle reduction, fixation or open realignment from timing and expertise.
4Provide close postoperative surveillance for osteonecrosis and counsel that risk remains high despite optimal treatment.
04ContralateralProtect the second physisThe opposite hip remains open after unilateral SUFE.+
1Examine and image the opposite hip at presentation and teach immediate return for any new pain or limp.
2Investigate atypical growth or endocrine features that increase bilateral risk.
3Discuss prophylactic fixation for selected high-risk children, balancing surgery against probability and follow-up reliability.
4Continue surveillance until physeal closure when observation is chosen.
Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
Controls pain during protected transfer and the short bridge to surgical stabilisation.
Paracetamol during non-weight-bearing assessment
Prescribe the current BNFC age- and weight-based oral dose, recording the exact milligrams, formulation volume, minimum interval and daily maximum for that child.
Verify weight, liquid concentration, liver risk and other paracetamol products; pain improvement does not permit walking or hip manipulation.
Adds non-opioid analgesia without replacing urgent mechanical stabilisation.
Ibuprofen for selected stable children
Use the BNFC age- and weight-specific oral dose for a short course when hydration, kidney function, bleeding risk and perioperative plan permit it.
Avoid with dehydration, renal impairment, active gastrointestinal bleeding and NSAID-sensitive asthma and follow fasting and anaesthetic instructions.