Clean FRCS notes with inline figures
Child complain of knee pain**
•“Medial knee pain in child with normal knee XR”
•SCREEN FOR HIP!!!
•Xray showing pelvis of skeletally immature patient with abnormalities over left proximal femur (looks to be around 12 yo based on GT, triradiate cartilage and LT)
•Slipped capital femoral epiphysis SCFE
•Klein’s line (Trethowan's Sign = when Klein line does not cut the epiphysis)
•Widened physis and decreased epiphyseal height
•Increased distance between the teardrop and the femoral neck metaphysis.
•Metaphyseal blanch sign of steel
•Carpener’s sign (normal AP: posterior acetabular margin cuts across the medial corner of the upper femoral metaphysis. In SUFE, the entire metaphysis is lateral to the posterior acetabular margin)
Signs of chronic SCFE:
•metaphysis smooth and sclerotic with callus formation
•metaphysis widens (coxa magna)
•No features of slip on the contralateral side (20% bilateral)
Differential is #
History
•1. Timing (chronicity)
•2. Able to walk at all (stability)
•3. Any preexisting illness or risk factors (endocrinopathy - hypothyroid, GH def, hypogonadism, renal failure)
•4. Sx on other side (20% bilateral, 80% chronic)
Examination
•See if patient can stand
•Position of limb
•Chronic – obligatory ER with flexion (Drenman’s sign)
Classification: chronicity, stability, severity
•Chronicity: pre-slip, acute, chronic, acute on chronic (no bearing on prognosis)
•Stability: Loder
•Stable <10% AVN
•Unstable 50% AVN
•Severity: Southwick angle in frog view, Wilson grade in AP view
Xray frog if stable, cross table if unstable
For Southwick classification (line perpendicular to base of epiphysis and line along shaft, compare with contralateral side)
•<30, 30-50, >50
•if bilateral slip, then Southwick angle is calculated by subtracting 12 degrees (normal angle)
Wilson’s grades: Epiphyseal-metaphyseal method (AP View)
•<1/3, 1/3-2/3, >2/3
Management
•Aim: to prevent further slip, promote physeal closure, prevent complications
•Natural history (Weinstein CORR 1996) – 28 untreated patients → increase displacement, degree of displacement is proportional to the risk of OA
•Unstable - O&T emergency, aim at preventing further slippage and allow physis to fuse in 6hrs (8-24hr)
•Go for in-situ pinning
•Stable, still pin in-situ, just not that urgent
•Also say whether go for prophylactic pin
•Risk factors for bilateral: Young (E: <10y), obese (E: not absolute), endocrinopathy (YOE)
| Type / group | Definition / note |
|---|---|
| E | Inability to come back fu / tell pain |
•1. GA
•2. Xray guidance
•3. Supine on traction table
•4. NO traction / forceful manipulation / only serendipitous reduction
•5. Very careful during positioning
•6. Triangulation technique to define entry point. Expect anterior entry (anterior aspect of femoral neck at head neck junction)
•7. One pin aiming at center center position, crossing perpendicular to physis, with adequate purchase and tip below subchondral bone, cross physis by at least 4 threads
•8. Cannulated, titanium, 6.5mm partially threaded screw with reverse cutting flutes
•9. Avoid multiple puncture → chondrolysis
•10. Capsulotomy (theoretical benefit but no strong evidence to support)
•JPO Dodwell metanalysis 2019- no stat significant decrease in odds of AVN. But recommend routine capsulotomy for all unstable SCFE as it adds little to the surgical procedure and may minimise risk of devastating insult to femoral head
•Consider contralateral pinning if
•(22% contralateral slip in 18 month)
•Young <10y (open triradiate cartilage)
•Systemic disease (hypothyroid, GH def, hypogonadism, renal failure)
•Obese / retroverted neck
•?Lost to FU
•Radiological markers to aid decision making – posterior slope angle (>14deg – 83% risk) and modified oxford bone age
One pin vs two pin:
•Theoretically 2 pins more stable, BUT
•Check/perform avoid superior quadrant of femoral head (where retinacular artery enters)
•Posterior aspect also avoid (in-out-in can damage posterior blood supply)
•Grade 3 slips or above → 25% contact only, limited corridor for pins
•Karol JPO 1992: Resistance to further slip was not proportional to screw number. Single screw fixation in slipped epiphyses is recommended because the small gains in stiffness with a second screw do not offset the risk of complications.
Any other option for severe type:
•Refer to specialist center for consideration
•Open reduction and fixation with Modified Dunn’s procedure
•Based on anatomy that MFCA is protected by obturator externus muscles
•Incision like posterior approach, Z shaped incision to capsule, avoid obturator externus, anterior dislocation of hip
•Reduction and fix with multiple pins
Rehab:
•Stable – weight bear
•Unstable – NWB
Follow-up checklist
•Pathological side fixation, complication (early: recurrent slippage, chondrolysis, Late: AVN, OA, FAI)
•Contralateral side
•FU until epiphyseal closure
•What if patient p/w pain + stiffness in FU
•R/O infection
Xray to see joint space. Chondrolysis if <3mm
•RF: manipulation, immobilization, hardware through head
•Rx: supportive, ?arthrodesis
•Definition: Disorder of the proximal femoral physis that leads to slippage of the metaphysis relative to the femoral head
•SCFE is misnomer: femoral head does not move, metaphysis slip and rotates
•Chronicity: acute <3w, chronic >3w, acute on chronic >3w with more pain → no implication on prognosis, management
•Timing of operation and pinning of contralateral hip is BOTH CONTROVERSIAL
•May present with knee pain due to radiation by obturator nerve
•Deformity: Extension, ER, varus
•Loss flexion, IR, abduction
•Cam type FAI (anterior impingement)
•Accelerated osteoarthritis due to anterior impingement
•PIS vs surgical dislocation for severe slip
•Metanalysis 2017 J O&T: surgical dislocation 3% AVN but better patient satisfaction rates whereas PIS has 1.5% AVN rate and lower satisfaction rates