March 2021

3/22/2021 | BY Rubini Pathy, MD FRCSC

5 Tips for Diagnosing and Managing a SCFE

1. SCFE: DEFINITION, EPIDEMIOLOGY, & ETIOLOGY
  • Disruption of the proximal femoral physis
    • Anterior displacement and external rotation of the proximal femoral metaphysis with variable posterior displacement of the epiphysis, which remains in the acetabulum (1)
      • rare subtype: “valgus slip”: antero-medial neck translation & posterovalgus inclination of the femoral head (1) definition-pic-1.png
  • Most common hip disorder in adolescents (1 to 100 per 100, 000) (2)
  • Affects Boys > Girls (1.5:1) (3.4)
  • Average Age of onset:
    • Boys: 12.7 to 13.5 y.o (3,4)
    • Girls: 11.2 to 12 y.o (3,4)
  • Bilateral slip: 20 to 80%5 – usually asynchronous
  • Pathophysiology
    • Mechanical overloading of a healthy physis
      • Obesity (6)
      • Anatomic characteristics
        • Femoral or acetabular retroversion (7,8)
        • Increased obliquity of the proximal femoral physis (9,10)
    • Normal loading of a weak physis
      • Endocrine or other underlying disorders
        • Consider when age < 10 y.o or > 16 y.o or if BMI < 50th percentile
  • Other risk factors
    • Ethnicity: Black / Native American / Hispanic > White (3)
    • Seasonal variations: higher incidence in summer (11)
    • Regional: USA - higher incidence in the Northeast and West (3,11)

2. DIAGNOSING A SCFE – KEY POINTS: CLINICAL PRESENTATION
  • History
    • Age
    • Groin, thigh or knee pain – acute vs. chronic vs. “acute-on-chronic”
    • Limp – with or without pain
      • Ability to weightbear with or without crutches (Loder Classification) (12)
        • Stable: able to WB (~10% risk of AVN)
        • Unstable: unable to WB (up to 50 % risk of AVN)
        • NB: Loder clinical classification may not correlate with intra-op stability (13)
          • 29% of clinically stable slips were unstable intra-op
    • o +/- history of trauma
    • **** Diagnosis is often delayed: Average time from first physician visit to diagnosis (14)
      • 94 days (non-ortho provider) vs. 2.9 days (ortho provider)
      • Significant delay if knee pain was presenting symptom (110 days vs 59 days: presentation to dx)
  • Physical Examination
    • External foot progression angle
    • “Obligate external rotation”
      • Hip externally rotates when assessing hip flexion
    • Limited hip internal rotation
    • BMI
  • Imaging
    • Supine AP Pelvis and bilateral frog leg views
    • ID slip & Quantify severity of slip (see xray examples below)
      • Klein’s line on AP
        • Line along superior femoral neck should normally intersect the epiphysis
      • Southwick (Head-Shaft) Angle on frog leg lateral (1)
        • Angle between the femoral shaft and a line perpendicular to the epiphysis
        • This angle is then subtracted from the contralateral normal hip
        • In bilateral SCFE: subtract 10 degrees
        • Mild (0–30°), moderate (30–60°), or severe (> 60°)
      • % slip: how much the metaphysis has slipped on the epiphysis
        • Mild: neck displaced < 1/3 diameter of the epiphysis, Moderate: 1/3 to ½; Severe: > ½
      • “Pre-slip”: Widening or irregularity of physis may be the only sign (MRI may be helpful)
      • CT / MRI useful if planning a surgical hip dislocationDiagnosing-pic-1.png






















3. MANAGEMENT GOAL & OPTIONS
  • GOAL
    • STABILIZE the slip to
      • MINIMIZE THE RISK OF AVN
      • PREVENT FURTHER DEFORMITY
        • Existing and further deformity can cause femoro-acetabular impingement, intraarticular cartilage and labral injury, symptomatic degenerative osteoarthritis
      • Eliminate pain
  • OPTIONS
    • In situ pinning
      • Most common technique
      • Stabilize the slip with no attempt to correct the current deformity
      • May require future surgery for symptomatic deformity correction
    • Surgical hip dislocation with acute correction of deformity (Modified Dunn osteotomy) and stabilization of slip (15,16)
      • Option in high volume centers with experienced surgeons to minimize the moderate risk of AVN
    • Open reduction and stabilization (17): described in one center
4. TIPS TO PERFORMING AN IN-SITU PINNING OF A SCFE
in-situ-pic-1.png
  • In situ pinning
    • Might get “serendipitous” reduction
    • No attempt at closed reduction
  • Anterior start on femoral neck
    • At or lateral to the intertrochanteric line
      • To avoid impingement with ROM
  • Cannulated 6.5 / 7.3 mm screw
  • Screw placed perpendicular to physis, center of epiphysis
  • At least 4 threads across physis (in epiphysis)
  • Do not violate subchondral bone
    • “approach-withdraw” test using fluoroscopy
    • screw tip should at least 5 mm from subchondral bone on all views
5. OTHER CONSIDERATIONS
  • Post-operative care
    • Usually protected WB if unstable, WBAT if stable
    • Follow up until physeal closure
    • At follow up visits: always ask about symptoms on the side of the slip and contralateral hip / thigh / knee pain
    • On follow-up AP and bilateral frog leg xrays, look for
      • Slip progression
      • Chondrolysis (narrowing of joint space < 3 mm, usually due to screw penetration)
      • AVN
      • Screw tip position and # of threads across physis
      • Contralateral slip
      • Complications arising from the deformity – FAI
  • Prophylactic pinning of contralateral hip
    • Controversial (18,19)
    • Relative Indications
      • Age : Boys < 12, Girls < 10
      • Underlying disorder (Endocrinopathy / radiation)
      • Poor follow-up potential
      • Modified Oxford Bone Age Score 16-18 or open tri-radiate (20)
      • Posterior sloping angle > 14 ° (21)
      • Posterior epiphyseal tilt > 10 ° (22)
other-considerations-pic-1.png
  • Single vs. Multiple screws
    • Controversial
    • Consider for unstable, displaced hips: 66% stronger fixation with 2 screws (23)
    • Decreased complication rate with one screw (24)
      • 1 screw = 4.6%, 2 screws = 19.6%, 3 screws = 36%
      • Single screw fixation is 77% as stable as double screw fixation
  • Complications
    • AVN
    • Chondrolysis
    • Peri-implant fracture
    • Progression of slip
    • Residual proximal femoral deformity limiting ROM or causing FAI
    • Leg length discrepancy
    • Degenerative OA
    • Contralateral slip





REFERENCES
1. Millis MB. SCFE: clinical aspects, diagnosis, and classification. J Child Orthop. 2017;11:93–8.
2. Novais EN, Millis MB. Slipped capital femoral epiphysis: prevalence, pathogenesis, and natural history. Clin
Orthop Relat Res.2012;470:3432–8.
3. Lehmann CL, Arons RR, Loder RT, Vitale MG. The epidemiology of slipped capital femoral epiphysis: an update. J
Pediatr Orthop. 2006;26:286–290.
4. Loder RT. The demographics of slipped capital femoral epiphysis. An international multicenter study. Clin Orthop
Relat Res. 1996;322:8–27.
5. Loder RT, Aronson DD, Greenfield ML. The epidemiology of bilateral slipped capital femoral epiphysis. A study of
children in Michigan. J Bone Joint Surg Am. 1993;75:1141–1147.
6. Manoff EM, Banffy MB, Winell JJ. Relationship between bod ymass index and slipped capital femoral epiphysis. J
Pediatr Orthop. 2005;25:744–6.
7. Gelberman RH, Cohen MS, Shaw BA, Kasser JR, Griffin PP, Wilkinson RH. The association of femoral retroversion
with slipped capital femoral epiphysis. J Bone Joint Surg Am. 1986;68:1000–1007
8. Ezoe M, Naito M, Inoue T. The prevalence of acetabular retroversion among various disorders of the hip. J Bone
Joint Surg Am. 2006;88:372–379
9. Mirkopulos N, Weiner DS, Askew M. The evolving slope of the proximal femoral growth plate relationship to
slipped capital femoral epiphysis. J Pediatr Orthop. 1988;8:268–273.
10. Pritchett JW, Perdue KD. Mechanical factors in slipped capital femoral epiphysis. J Pediatr Orthop. 1988;8:385–
388.
11. Loder RT. A worldwide study on the seasonal variation of slipped capital femoral epiphysis. Clin Orthop Relat
Res. 1996;322:28–36.
12. Loder RT, Richards BS, Shapiro PS, Reznick LR, Aronson DD. Acute slipped capital femoral epiphysis: the
importance of physeal stability. J Bone Joint Surg Am. 1993;75:1134–40.
13. Ziebarth K, Domayer S, Slongo T, Kim YJ, Ganz R. Clinical stability of slipped capital femoral epiphysis does not
correlate with intraoperative stability. Clin Orthop Relat Res 2012;470:2274-2279.
14. Hosseinzadeh P, Iwinski HJ, Salava J, Oeffinger D. Delay in the Diagnosis of Stable Slipped Capital Femoral
Epiphysis. J Pediatr Orthop. 2017 Jan;37(1):e19-e22.
15. SankarWN,Vanderhave KL, Matheney T, Herrera-Soto JA, Karlen JW. The modified Dunn procedure for unstable
slipped capital femoral epiphysis. J Bone Joint Surg Am. 2013;95:585–91.
16. Upasani VV, Matheney TH, Spencer SA, Kim Y-J, Millis MB, Kasser JR. Complications after modified Dunn
osteotomy for the treatment of adolescent slipped capital femoral epiphysis. J Pediatr Orthop. 2014;34:661–7.
17. Parsch K, Weller S, Parsch D. Open reduction and smooth Kirschner wire fixation for unstable slipped capital
femoral epiphysis. J Pediatr Orthop. 2008;29:1–8.
18. Kocher MS, Bishop JA, Hresko MT, Millis MB, Kim YJ, Kasser JR. Prophylactic pinning of the contralateral hip after
unilateral slipped capital femoral epiphysis. J Bone Joint Surg Am. 2004 Dec;86(12):2658-65.
19. Schultz WR, Weinstein JN, Weinstein SL, Smith BG. Prophylactic pinning of the contralateral hip in slipped capital
femoral epiphysis : evaluation of long-term outcome for the contralateral hip with use of decision analysis. J
Bone Joint Surg Am. 2002 Aug;84(8):1305-14.
20. Popejoy D, Emara K, Birch J. Prediction of contralateral slipped capital femoral epiphysis using the modified
Oxford bone age score. J Pediatr Orthop. 2012 Apr-May;32(3):290-4.
21. Phillips PM, Phadnis J, Willoughby R, Hunt L. Posterior sloping angle as a predictor of contralateral slip in slipped
capital femoral epiphysis. J Bone Joint Surg Am. 2013 Jan 16;95(2):146-50.
22. Maranho DA, Ferrer MG, Kim YJ, Miller PE, Novais EN. Predicting Risk of Contralateral Slip in Unilateral Slipped
Capital Femoral Epiphysis: Posterior Epiphyseal Tilt Increases and Superior Epiphyseal Extension Reduces Risk. J
Bone Joint Surg Am. 2019 Feb 6;101(3):209-217.
23. Kishan S, Upasani V, Mahar A, Oka R, Odell T, Rohmiller M, Newton P, Wenger D. Biomechanical stability of
single-screw versus two-screw fixation of an unstable slipped capital femoral epiphysis model: effect of screw
position in the femoral neck. J Pediatr Orthop. 2006 Sep-Oct;26(5):601-5.
24. Karol LA, Doane RM, Cornicelli SF, Zak PA, Haut RC, Manoli A 2nd. Single versus double screw fixation for
treatment of slipped capital femoral epiphysis: a biomechanical analysis. J Pediatr Orthop. 1992 Nov-
Dec;12(6):741-5.