1. Improvement of femoral head roundness after valgus femoral osteotomy in Legg-Calve-Perthes disease
Hui Taek Kim, MD and Seong Ho Bae, MD
Pediatric Orthopaedic Unit
Department of Orthopaedic Surgery
Pusan National University Hospital

2. Introduction
Deformation of the femoral head in Legg-Calve-Perthes disease (LCPD)
• Latter in fragmentation or early in regeneration
stage
Best time to perform surgery
• Avascular necrosis and fragmentation stage

3. Introduction Containment of the affected femoral head
• Abduction brace
• Soft tissue release and/or varus femoral osteotomy
• Salter innominate osteotomy
The results are frequently poor
• > 8 years old
• Uncontained femoral head and hinge abduction

4. Introduction Valgus femoral osteotomy (VFO) • Relieves hinge abduction
• Provides better functional range of movement
by rotating the less affected femoral head into
weight bearing position

5. Purpose
To quantify the changes of femoral head roundness after valgus femoral osteotomy
• Using new measuring method

6. Materials and Methods

7. 48 children Group 1: non-operative Tx. (25 hips)
Materials and Methods
48 children
• September 1997 to January 2006
Group 1: non-operative Tx. (25 hips)
• 21 hips in pillar B (19 > 8 yrs old)
• 4 hips in pillar C (2 > 8 yrs old )
Group 2: treated by VFO (23 hips)
• 7 hips in pillar B (3 > 8 yrs old)
• 16 hips in pillar C (7 > 8 yrs old)

8. Overall patient age was 8.3 years
Materials and Methods
Overall patient age was 8.3 years
• Group 1 : 8.7 years
• Group 2 : 8.1 years
Chiari OT : 10.2 years (3 cases)
Triple innominate OT : 6.5 years (2 cases)
Male : 43
Female : 5
Mean follow-up period : 6.4 years

9. Soft tissue release or shortening (×)
Materials and Methods
Indications for VFO
• Hip pain
• Decreased range of motion
• Hinge abduction on MRI and arthrography
• Significant deformity of the femoral head
Open wedge type
Soft tissue release or shortening (×)

10. Femoral head roundness
Materials and Methods
Femoral head roundness
• Roundness of the lateral third (RLT)
• Roundness of the medial third (RMT)
• Maximal epiphyseal height in middle third (MEH)
• Ratio of radii of curvature of the medial third over
the lateral third (RML)

11. Materials and Methods
Radiograph and MRI were taken at the same time (fragmentation stage)
MRI enables the visualization of the cartilaginous femoral head

12. Materials and Methods
Measuring methods

13. Image-analysis software
Materials and Methods
Most clear image
• Entire proximal femur
• Fragmentation stage in MRI / residual stage in AP
radiograph
Image-analysis software
• Adobe Photoshop
• Microsoft Power Point

14. Drawing • Femoral shaft axis • Femoral neck axis • Femoral head waist
Materials and Methods
Drawing
• Femoral shaft axis
• Femoral neck axis
• Femoral head waist
• Radius of circle in lateral and medial third of
femoral head (RLT and RMT)
• Maximal epiphyseal height (MEH) in middle third

15. First step Materials and Methods • Magnification
• Medial aspect of the femoral head and calcar
# Medial aspect of the femoral head and calcar
are minimally affected during disease process

16. Second step Materials and Methods • Femoral shaft and neck axis
• The most superolateral and inferomedial point of femoral head
• Base line a′ A’ a A

17. Third step Materials and Methods • Divide the base line into thirds
• Draw lines parallel to the femoral neck axis through 2 points b′ a′ A’ B’ ‖ ‖ b ‖ B ‖ ‖ ‖ a A

18. Final step Materials and Methods
• Best fitting circle passing a′(A′) and b′(B′) placing the center
of circle to the median of the line connecting a′(A′) and b′(B′) ┐ b′ a′ A’ B’ b B r R a A
RLT
# Definition of circle : The set of all points in a plane
which are equidistant from a given point (center of circle)

19. Materials and Methods
The ratio of maximal epiphyseal height (MEH) to the waist of the femoral head
• Subchondral bone instead of articular cartilage (in MRI) b′ a′ A’ B’ b B W W a A
MEH

20. Materials and Methods
Differential coefficient is
decreased as the point of
contact moves toward middle
portion in ellipse
Maximal epiphyseal height
represent more effectively the
head growth or roundness in
the middle third

21. Final data analysis Materials and Methods
• Relative change of RLT (%) = × 100 (%)
r – R r ┐ b′ a′ A’ B’ b B r R a A
RLT
# Definition of circle : The set of all points in a plane
which are equidistant from a given point (center of circle)

22. Final data analysis Materials and Methods
• Relative change of MEH (%) = × 100 (%)
m – M m b′ a′ A’ B’ b B W W a A
MEH

23. Amount of collapse in lateral portion of deformed femoral head
# RML = ROC in medial 1/3 / ROC in lateral 1/3 (Rm / RL) r R R’ r’
ROC in lateral third : r
ROC in medial third : r’
The ratio of ROC (RML) : r’/r
ROC in lateral third : R
ROC in medial third : R’
The ratio of ROC (RML) : R’/R
D. Nelson, M. Zenios, K. Ward et al, JBJS 2007
* ROC : Radius Of Circle

24. Final Stulberg classification
Materials and Methods
Final Stulberg classification

25. Results

26. Measurements Group 23 21.4 7.8 0.65 → 0.81 (0.16)
Total
RLT (%)
MEH (%)
RML (△)
All hips
Nonoperative 25
13.2
3.9
0.74 → 0.84 (0.10)
Operative 23
21.4
7.8
0.65 → 0.81 (0.16) 48
Comparison of each value : p < by paired t-test

27. Comparison of each value : p < 0.05 by paired t-test
Measurements
Group
Total
RLT (%)
MEH (%)
RML (△)
Lateral pillar group B 28
15.0
4.5
0.76 → 0.88 (0.12)
Chron. Age ≤ 8.0 at disease onset
Nonoperative 19
16.8
0.76 → 0.90 (0.14)
Operative 4
10.2
3.5
0.74 → 0.82 (0.08) 23
Chron. Age > 8.0 at disease onset 2
5.5
4.4
0.82 → 0.88 (0.06) 3
16.7
5.6
0.73 → 0.84 (0.11) 5
Comparison of each value : p < by paired t-test

28. Comparison of each value : p < 0.05 by paired t-test
Measurements
Group
Total
RLT (%)
MEH (%)
RML (△)
Lateral pillar group C
26.6
9.6
0.59 → 0.78 (0.19)
Chron. Age ≤ 8.0 at disease onset
Nonoperative 2
17.4
2.7
0.70 → 0.81 (0.11)
Operative 9
31.2
12.5
0.53 → 0.76 (0.23) 11
Chron. Age > 8.0 at disease onset
13.2
4.0
0.69 → 0.78 (0.09) 7
27.3
9.4
0.61 → 0.80 (0.19) 20 20
Comparison of each value : p < by paired t-test

30. Final Stulberg classifications
Results
Final Stulberg classifications II
III
Group 1 (n=25) 10 15
Group 2 (n=23) 4 19
p = 0.09 by Pearson chi-square test

31. Conclusions

32. Femoral head roundness was improved
Conclusions
Femoral head roundness was improved
with ossification of the affected hip
More round femoral head can be expected
in the lateral pillar B hips than pillar C

33. However, VFO performed in the
Conclusions
However, VFO performed in the
fragmentation stage of lateral pillar C hips
leads to greater improvement in femoral
head roundness than does non-surgical
treatment of lateral pillar B hips

34. Case 1
M/7+3
Group 1

36. RMT
5.08
5.02 1%

37. RLT
8.04
6.00
25%

38. MEH
1.68/4.75
1.78/4.76 6%

39. RML
5.08/8.04 = 0.63
5.02/6.00 = 0.84
0.21

40. Case 2
M/10+0
Group 2

42. RMT
5.80
5.30 9%

43. RLT
9.29
6.34
32%

44. MEH
1.80
2.10
17%

45. RML
5.80/9.29 = 0.62
5.30/6.34 = 0.84
0.22

46. Thank you for your attention !