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- Epiphysis remains in place
- Metaphysis moves Anteriosuperiorly
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- Slip is through the zone of provisional calcification in zone of Hypertrophy
- [renal cause] = in secondary spongiosum
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- 60% with endocrinopathy has bilateral slips (Renal dystrophy, hypothyroid, Growth hormone)
- Renal failure osteodystrophy, Hypothyroidism, GH deficiency,
- Anatomical - increased femoral retroversion, acetabular retroversion
- Vertical physis in this age group (goes from 160 ° at birth to 125 ° at skeletal maturity ➔ increased shearing forces
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- Male, Obese, Adolescent 12 years old
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- Hx = Duration (acute on chronic), PMHx, function, hip or knee pain, age 12-13 yo
- 50% have hip pain, 25-50% have referred pain in knee (medial obturator nerve)
- BMI, weight
- Drehmann sign – obligatory External rotation of limb when flexing hip
- Ability to weight bear (stability)
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- By Stability = Loder (Loder et al. of 55 patients. 47% AVN in unstable, 0% in stable)
- Stable – able to WB with or without crutches
- Unstable – cannot WB even with crutches
- By chronicity
- Acute = < 3 week
- Chronic > 3 week (most common – 85%!)
- By severity = Southwick angle [can be AP]
- Mild < 30, mod 30-50, Severe > 30
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- XR - AP
- Trethowan’s sign = Klein’s line passes above epiphysis.
- Metaphyseal blanch sign of steel = crescent shape dense area (due to overlap of epiphysis and metaphysis)
- Features of Chronicity – Callus formation over infero-posterior neck
- XR – Frog leg lateral. -AVOID but do the cross table lateral.
- Southwick angle = perpendicular line from line from anterior and posterior tip of epiphysis \/ anatomical axis of diaphysis
- < 30 = mild
- 30-60 = moderate
- > 60 = severe
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- Cross table lateral instead of frog leg lateral
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- Aim is to prevent progression and fusion of the physis.
- My management of choice is “insitu single screw fixation using the “approach-withdrawal” technique
- This is done on a traction table, with no attempt at reduction or traction but achieving serendipitous reduction when patient is under GA and muscle relaxation
- Using II to plan the entry point:
- Guidepin placed perpendicular to the physis on AP image ➔ draw line
- Same done for lateral image
- Incision made at intersection of lines; the more the slip, the more anterior the entry point
- Guidepin advanced to anterolateral cortex, into center of epiphysis perpendicular to physis.
- Aim for 6.5mm or 7.3mm cannulated, fully threaded screw with 5 threads across and 5mm away from joint line (to prevent chondrolysis)
- I will rotate hip or C-arm during live fluoroscopy to obtain images that show the screw tip approach the subchondral bone and then subsequently withdraw from the bone. [sunrise sunset views]
- Postoperatively
- Stable – WBAT
- Unstable – NWB x 6/52, PWB x 6/52
- Follow up
- Till closure of contralateral physis
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- Sunrise Sunset views
- Fluoroscopy
- Inject dye through the cannulation of screw to see if go into joint.
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- Atypical slips - Female, < 10 yo, medical conditions (endocrinopathy)
- unreliable follow up.
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- AVN – 47% in unstable slips
- Chondrolysis
- Decrease in apparent joint space of > 2mm compared w contralateral hip.
- Radiographic OA - 27%
- FAI
- Due to Proximal femoral deformity Resulting from the external rotation deformity
- Mx = Proximal femoral intertrochanteric osteotomy to correct deformity (flex, valgus and internal rotate)
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- Decrease in apparent joint space of > 2mm compared w contralateral hip.
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- Cam type impingement in the anterolateral femoral metaphysis due to slip being pinned insitu
- Mx options:
- Arthroscopic bumpectomy
- Open bumpectomy with smith petersen approach
- Osteotomy - intertrochanteric e.g. Imhauser vs Subtrochanteric e.g. Southwick
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- Journal of Children’s orthopaedics Maranho et al. 2018
- Found that acetabular dysplasia observed in 25% of patients with SCFE
- Risk factors - age at slip, SCFE severity and femoral head overgrowth
jco-12-444.pdf1747.3KB
CONTROVERSIES IN SCFE
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- Controversial
- Lowndes et al. 2009 Meta-analaysis – for unstable SCFE, Fixation < 24 hour lower risk of AVN
- Philips JBJS 2001 follow up of 100 cases of SCFE over 26 years, 14 were unstable, fix < 24 hours, no risk of AVN
- In patient with unstable hips, I will therefore try to fix within 24 hours
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- Even though 2 screws show better biomechanical stability but one pin has lower risk of chondrolysis.
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- 5 threads. Carney et al. JPO 2003 - 37 children with 46 stable slips
- 20% of stable slips progressed and all had < 5 threads.
- None with > 5 threads progressed.
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- I will use a “reverse cutting, fully threaded screws” to facilitate future removal if required.
- Fully threaded vs partially threaded
- Mazzini et al. JPO 2012 – found that fully threaded screws had lower screw removal complication rates.
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- Consider in unstable to decompress
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- Possible role in unstable SCFE but no consensus
- Some authors suggest open reduction in acute slips. Techniques include
- Parsch technique – using fingers through the Watson- jones approach (TFL // Glute med) – to feel the slip and reduce under tactile guidance before driving pin across physis.
parsch2009 .pdf1047.6KB
- Dunn technique – Lateral position, Ganz trochanteric flip osteotomy, creation of retinacular flap and then anterior dislocation of hip [Hip + Pelvis Approaches]
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- Routine removal is controversial
- Some advocate due to risk of trochanteric bursitis, future stress riser or difficulty for future arthroplasty
- Risk of breakage of implant when removing
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- JPO 2014 - Christopher et al. 88 hips. Insitu fixation for 71, Dunn procedure for 17 hips.
- STABLE - 2 out of 10 stable hips with Dunn procedure developed AVN (20%)
- UNSTABLE - 2 of 7 unstable hips with Dunn procedure developed AVN (29%)
- Stable hips - Open reduction lead to AVN 20% (compared to 0% in Loder study) ➔ Should be done with caution
- Unstable - both problematic with high AVN rates
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