Combined Paed

SCFE - imaging and management

Pelvic radiographs in the skeletally immature hip, unstable slip and treatment options.

49 questions 4 source pages 1 fact-check flags

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Q1What are the X-ray signs of SCFE?▸

Klein's line (Trethowan's sign)
Widened physis with decreased epiphyseal height
Increased distance between the teardrop and femoral neck metaphysis
Metaphyseal blanch sign of Steel
Carpenter's sign (less overlap of metaphysis with posterior acetabular wall)

Q2What are the signs of chronic SCFE?▸

Metaphysis smooth and sclerotic with callus formation
Metaphysis widens (coxa magna)

Q3How is SCFE classified?▸

Chronicity: pre-slip, acute, chronic, acute-on-chronic (no bearing on prognosis)
Stability (Loder): stable vs unstable (< 10% vs 50% AVN)
Severity: Southwick angle on frog view; Wilson grade on AP view
Wilson: I < 33%, II 33-50%, III > 50% of slip over physis

Q4What is the management and in-situ pinning technique for SCFE?▸

Aim: prevent further slip, promote physeal closure, prevent complications
Unstable = O&T emergency: aim at preventing further slippage and allow physis to fuse in 6hrs; in-situ pinning; stable also pinned, less urgent
also say whether go for prophylactic pin
GA, X-ray guidance, supine on traction table; no traction or forceful manipulation
Triangulation for entry point; one pin center-center, perpendicular to physis, crossing by at least 4 threads
6.5 mm cannulated titanium partially threaded screw with reverse cutting flutes; avoid multiple punctures -> chondrolysis

Q5When is contralateral (prophylactic) pinning considered?▸

Young < 10 yo (open triradiate cartilage)
Systemic disease: hypothyroid, GH deficiency, hypogonadism, renal failure
Obese/ retroverted neck
? Lost to follow-up
22% contralateral slip in 18 months

Q6What is looked for at follow-up after SCFE?▸

Fixation of the pathological side; early: recurrent slippage, chondrolysis
Late: AVN, OA, FAI
Contralateral side
Follow up until epiphyseal closure
Pain + stiffness: rule out infection; chondrolysis if joint space < 3 mm
Chondrolysis risk factors: manipulation, immobilization, hardware through head

Q7What is the definition of SCFE?▸

Disorder of the proximal femoral physis leading to slippage of the epiphysis relative to the femoral neck

Q8What history points are important in SCFE?▸

Timing (chronicity); able to walk at all (stability)
Preexisting illness/risk factors: hypothyroidism, GH deficiency, hypogonadism, renal failure
Symptoms on the other side (20% bilateral, 80% chronic)

Q9What is Drehmann's sign?▸

In chronic SCFE: obligatory external rotation with flexion
See if patient can stand; check the position of the limb

Q10What is the Southwick angle classification?▸

Measured on frog view: line perpendicular to the base of the epiphysis vs line along the shaft, compared with the contralateral side
Categories: < 30, 30-60, > 60
If bilateral, subtract 12 degrees from the corresponding lateral epiphyseal shaft angle

Q11Which X-ray view is used in SCFE depending on stability?▸

Frog lateral if stable
Cross-table if unstable

Q12What is the natural history of untreated SCFE?▸

Weinstein CORR 1996: 28 untreated patients
Increasing displacement over time
Degree of displacement is proportional to the risk of OA

Q13What radiological markers aid the decision for prophylactic pinning?▸

Posterior slope angle (>14deg – 83% risk)
Modified Oxford bone age (Popejoy 2012 JPO): score femoral head, LT, ilium, GT, triradiate cartilage
Score range 16-26; < 18 = 85-97% risk; 20 = 5%; > 21 = 0-1%

Q14What is the rehabilitation after SCFE pinning?▸

Stable: weight bear
Unstable: non-weight bearing

Q15How does SCFE present and what deformity results?▸

May present with knee pain due to radiation by the obturator nerve
Deformity: extension, external rotation, varus
Loss of flexion, internal rotation, abduction
CAM-type FAI and accelerated osteoarthritis from anterior impingement

Q16What is the role of capsulotomy in unstable SCFE?▸

10. Capsulotomy: theoretical benefit, no strong evidence
Dodwell JPO 2019 meta-analysis: no statistically significant decrease in odds of AVN
Still recommend routine capsulotomy for all unstable SCFE - adds little and may minimise devastating insult to the femoral head

Q17What does the 2017 J O&T meta-analysis compare for severe slip?▸

Surgical dislocation (Modified Dunn): 3% AVN but better patient satisfaction
In-situ pinning: 1.5% AVN and lower satisfaction

Q18Which SCFE management decisions remain controversial?▸

Timing of operation
Pinning of the contralateral hip

Q19Any other options for unstable severe slip?▸

Modified Dunn procedure

Q20When is the Modified Dunn procedure for unstable severe slip performed?▸

Done in the elective setting

Q21What are the steps of the Modified Dunn approach for severe slip?▸

Gibson interval (gluteus medius / gluteus maximus)
Trochanteric flip osteotomy
Z capsulotomy (from troch ridge to acetabulum along neck of femur, distal anterior towards calcar, parallel towards posterior)
Cut ligamentum teres -> ER + adduction -> anterior dislocation

Q22What is the AVN risk of this procedure?▸

AVN up to 25% in inexp hands

Q23What is the anatomical basis of the Modified Dunn procedure?▸

The MFCA is protected by obturator externus
Avoid obturator externus during the approach

Q24How is the slip fixed after surgical dislocation?▸

Reduction and fixation with multiple pins

Q25Describe the radiographic findings in this case.▸

Flattened, irregular, fragmented left proximal femoral epiphysis with lateral extrusion
Cystic changes over the metaphyseal area and lucency over the lateral epiphysis, consistent with Gage sign
Widened medial joint space
Contralateral hip not involved (10% bilateral, never same time)
Working diagnosis: Perthes disease, in the fragmentation phase

Q26What is the Waldenstrom classification and what are the differential diagnoses?▸

Waldenstrom stages: initial, fragmentation, reossification, remodelling
This case is in the fragmentation phase
Unilateral Ddx: septic arthritis, Meyer's disease, MED
Bilateral Ddx: hypothyroidism, lipid storage disease, Meyer's dysplasia, MED, sickle cell
History/PE focus: Age, gender, body built, onset of symptoms, at-risk signs (FOOBS), r/o Ddx, ROM

Q27What are the clinical and radiological at-risk signs in Perthes disease?▸

Clinical at-risk signs (FOOBS): female, old, obese, bilateral, stiff
Catterall sign: hip flexion with obligatory external rotation
Radiological (Catterall): Gage sign (inverted V lucency lateral to the epiphysis)
Horizontal physis and lateral subluxation of the femoral head
Calcification lateral to the epiphysis and metaphyseal cyst

Q28What is the aim of treatment in Perthes disease and what is the natural history?▸

Pain control (rest, analgesics)
Maintain ROM (physio, temporary NWB)
Contain the hip during the critical period of biologic plasticity during creeping substitution so the head remodels with less incongruity
Containment position: abduction and internal rotation
Natural history: We know from the classic Iowa study with a 50yr FU that 40% need arthroplasty if left untreated. Counsel patient regarding containment. Still has a possibility of future OA
Non-operative containment options: observation, activity restriction, NWB + ROM exercise (abd + IR), Petrie cast, A-frame

Q29What is the lateral pillar classification and how does it guide management?▸

Based on AP X-ray, comparing both sides (Herring); lateral pillar 25%, central 50%, medial 20-35%
A = normal height; B = > 50%; B/C = exactly 50% or very narrow lateral pillar >50% of original height / very little ossification but > 50%; C = < 50%
Herring study (2004 JBJS): A and B < 8 yo do well regardless; B and B/C > 8 yo improve with surgery; B/C < 8 and C poor regardless of treatment; no significant effect regardless of treatment in those <8yo
For this case (lateral pillar B or B/C, > 8 yo): surgical containment improves outcome
Surgical containment: proximal femoral VDRO (at most 20deg) or ROWO +/- pelvic osteotomy
Outcome at maturity by Stulberg classification: I normal, II spherical congruent, III mushroom congruent, IV flat congruent, V incongruent

Q30What is the blood supply to the femoral head by age?▸

< 4 yo: equal contribution by MFCA and LFCA
4-10 yo: LFCA regresses and supplies metaphysis only
10-14 yo: increased contribution from ligamentum teres
> 14 yo: anastomosis between the three systems

Q31What further investigations are needed in suspected Perthes disease?▸

WBC (infection), lipid (storage disorder), ESR, CRP
Bone profile (tumour), TSH (hypothyroid), peripheral smear (sickel cell)
XR frog-leg lateral; +/- USG, aspiration if infection suspected

Q32What is the etiology of Perthes disease?▸

Anatomical
Hydrostatic pressure
Thrombophilic

Q33What are the operative containment options in Perthes disease and their problems?▸

Proximal femoral VDRO (at most 20deg) or ROWO - problems: short limb and Trendelenburg gait
Pelvic osteotomy - re-directional (Salter): potential lengthening increases pressure on the head -> AVN
Combination with femoral osteotomy increases coverage by 20%
Shelf to prevent lateral subluxation/no longer containable; Chiari
Valgus osteotomy for hinged abduction (reposition hinge, correct shortening, improve abductor function)

Q34What are the prerequisites for surgical containment in Perthes disease?▸

Prerequisites include timing: fragmentation phase
Containable: good range on examination
> XR – spherical and congruent reduction, containable upon abduction XR/ intraop arthrogram

Q35Take me through the surgical steps of proximal femoral varus osteotomy.▸

Preop plan the amount of varisation; GA; adductor release if tight
Lateral subvastus approach; elevate periosteum
Paediatric proximal locking plate: 3.5 mm if < 35 kg, 5 mm if > 35 kg
Jig angle = plate angle + desired varisation; fix plate proximally then remove it
Mark rotation, use 2 K-wires above and below the osteotomy, osteotomy with oscillating saw
Fix plate proximally then distally; Add some internal rotation or extension for better containment

Q36What is the postoperative care and follow-up after Perthes surgery?▸

NWB walking, HKO
Follow up until maturity

Q37What other problems occur in Perthes disease?▸

LLD, Trendelenburg
Pain: labral tear, loose body, hinged abduction, FAI

Q38What is the advantage of surgical containment according to B Joseph?▸

The patient will go through the fragmentation phase faster

Q39What were the limitations of Herring's study?▸

Based on AP view only
7/12 had surgery before reliable classification
1/3 needed upgrade; only 4% in group A on final grading
Difficult in bilateral disease

Q40What did Benjamin Joseph's study recommend for containment?▸

Factors: age at onset, femoral head extrusion (> 20% Reimer migration index), ROM
Containment ASAP if: >= 8 yo with extrusion and reduced ROM (restore motion with traction/abduction cast for 6 weeks first)
< 8 yo with extrusion
< 8 yo: femoral osteotomy (more remodelling, less Trendelenburg later)
>= 8 yo: acetabular osteotomy (less shortening)

Q41What are the limitations of non-operative containment with casts?▸

Petrie cast / A-frame must be worn for 6 months to 1 year
Problem: cannot guarantee abduction

Q42Describe the X-ray findings of developmental coxa vara.▸

Bilateral coxa vara deformity
Vertical physis with increased HE angle (> 25 abnormal)
Decreased neck shaft ankle (<125 abnormal)
Coxa breva
Fairbank triangle: Inverted Y shape lucency in inferior femoral neck (ossification defect)
Acetabulum and tear drop normal

Q43What are the causes of coxa vara?▸

Acquired: Perthes, chronic SCFE, trauma, infection
Developmental
Dysplasia: MED, SED, OI
Metabolic: cretinism
Congenital: PFFD; bilateral in 30-50%

Q44What are the clinical features of coxa vara?▸

Trendelenburg gait
LLD and high riding greater trochanter
Excessive lumbar lordosis
Restricted hip ROM

Q45What is the prognosis by HE angle and when is surgery indicated?▸

< 45: 20% resolve
45-60: uncertain
> 60: will progress
VDRO if HE > 60 and NSA < 110 (subtrochanteric if < 3 yo, intertrochanteric if > 3 yo)
Goal: overcorrect NSA, correct LLD and version, restore abductor tension; aim HE < 30

Q46What is the pathomechanics of coxa vara?▸

Decreased neck-shaft angle with an ossification defect in the inferior femoral neck
-> vertical physis
-> increased shearing force

Q47What is the diagnosis and inheritance of developmental coxa vara?▸

Developmental coxa vara
No clear genetic inheritance
Bilateral in 30-50%

Q48What history is relevant in coxa vara?▸

Previous hip trauma or infection
Associated skeletal abnormalities
Perinatal history and family history

Q49What preoperative planning is needed before VDRO for coxa vara?▸

CT PRE OP for associated deformities: coxa breva, femoral retroversion, acetabular dysplasia, GT overgrowth
Lateral approach, protect physis and periosteum
Goal: overcorrect NSA, correct LLD, correct version, restore abductor tension; aim HE < 30

Fact check

Classic Iowa study with 50-year follow-up shows 40% of untreated Perthes disease need arthroplasty — outdated/overstated — The 40% figure comes from a selected historical Iowa cohort (McAndrew & Weinstein, mean 47.7 years follow-up: 15/37 hips). A modern nonoperative cohort (Oslo, mean 48 years) reported only 19% THA, so 40% should not be quoted as the universal natural history. — (medium confidence) — source

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SCFE - imaging and management

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