Improvement of femoral head roundness Improvement of femoral head roundness after valgus femoral osteotomyafter valgus femoral osteotomyin Legg-Calve-Perthes disease in Legg-Calve-Perthes disease

Pediatric Orthopaedic UnitDepartment of Orthopaedic SurgeryPusan National University Hospital

Hui Taek Kim, MD and Seong Ho Bae, MD

IntroductionIntroduction

Deformation of the femoral head in Deformation of the femoral head in Legg-Calve-Perthes disease (LCPD)Legg-Calve-Perthes disease (LCPD)

• • Latter in fragmentation or early in regenerationLatter in fragmentation or early in regeneration stagestage

Best time to perform surgeryBest time to perform surgery • • Avascular necrosis and fragmentation stageAvascular necrosis and fragmentation stage

IntroductionIntroduction

Containment of the affected femoral headContainment of the affected femoral head • • Abduction braceAbduction brace • • Soft tissue release and/or varus femoral osteotomy Soft tissue release and/or varus femoral osteotomy • • Salter innominate osteotomySalter innominate osteotomy

The results are frequently poorThe results are frequently poor • • > 8 years old> 8 years old • • Uncontained femoral head and hinge abductionUncontained femoral head and hinge abduction

IntroductionIntroduction

Valgus femoral osteotomy (VFO)Valgus femoral osteotomy (VFO) • • Relieves hinge abductionRelieves hinge abduction

• • Provides better functional range of movementProvides better functional range of movement

by rotating the less affected femoral head intoby rotating the less affected femoral head into

weight bearing positionweight bearing position

PurposePurpose

To quantify the changes of femoral head To quantify the changes of femoral head roundness after valgus femoral osteotomyroundness after valgus femoral osteotomy

• • Using new measuring methodUsing new measuring method

Materials and MethodsMaterials and Methods

48 children48 children •• September 1997 to January 2006September 1997 to January 2006

Group 1: Group 1: non-operative Tx. non-operative Tx. (25 hips) (25 hips) • • 21 hips in pillar B (19 > 8 yrs old)21 hips in pillar B (19 > 8 yrs old) • • 4 hips in pillar C (2 > 8 yrs old )4 hips in pillar C (2 > 8 yrs old )

Group 2: Group 2: treated by VFO treated by VFO (23 hips)(23 hips) • • 7 hips in pillar B (3 > 8 yrs old)7 hips in pillar B (3 > 8 yrs old) • • 16 hips in pillar C (7 > 8 yrs old)16 hips in pillar C (7 > 8 yrs old)

Materials and MethodsMaterials and Methods

Overall patient age was 8.3 Overall patient age was 8.3 yearsyears • • GGroup 1 : 8.7 yearsroup 1 : 8.7 years • • Group 2 : 8Group 2 : 8.1 years.1 years Chiari OT : 10.2 years (3 cases)Chiari OT : 10.2 years (3 cases) Triple innominate OT : 6.5 years (2 cases)Triple innominate OT : 6.5 years (2 cases)

Male : 43Male : 43 Female : 5Female : 5

Mean follow-up period : 6.4 yearsMean follow-up period : 6.4 years

Materials and MethodsMaterials and Methods

Indications for VFOIndications for VFO •• Hip painHip pain • • Decreased range of motionDecreased range of motion • • Hinge abduction on MRI and arthrographyHinge abduction on MRI and arthrography • • Significant deformity of the femoral headSignificant deformity of the femoral head

Open wedge typeOpen wedge type

Soft tissue release or shortening (Soft tissue release or shortening (×)×)

Materials and MethodsMaterials and Methods

Femoral head roundnessFemoral head roundness •• Roundness of the lateral third (RLT) Roundness of the lateral third (RLT) •• Roundness of the medial third (RMT) Roundness of the medial third (RMT) •• Maximal epiphyseal height in middle third (MEH) Maximal epiphyseal height in middle third (MEH)

•• Ratio of radii of curvature of the medial third over Ratio of radii of curvature of the medial third over the lateral third (RML) the lateral third (RML)

Materials and MethodsMaterials and Methods

• Radiograph and MRI were taken at the same time (fragmentation stage)• MRI enables the visualization of the cartilaginous femoral head

Materials and MethodsMaterials and Methods

Measuring methodsMeasuring methods

Materials and MethodsMaterials and Methods

Most clear imageMost clear image • • EEntire proximal femur ntire proximal femur

• • FFragmentation stage in MRI / residual stage in APragmentation stage in MRI / residual stage in AP

radiographradiograph

Image-analysis softwareImage-analysis software • • Adobe PhotoshopAdobe Photoshop

• • Microsoft Power PointMicrosoft Power Point

Materials and MethodsMaterials and Methods

Drawing Drawing • • FFemoral shaft axisemoral shaft axis

•• Femoral neck axisFemoral neck axis

• • FFemoral head waistemoral head waist

•• Radius of circle in lateral and medial third of Radius of circle in lateral and medial third of

femoral head (RLT and RMT)femoral head (RLT and RMT)

•• Maximal epiphyseal height (MEH) in middle thirdMaximal epiphyseal height (MEH) in middle third

Materials and MethodsMaterials and Methods

First stepFirst step • • MMagnificationagnification • • Medial aspect of the femoral head and calcarMedial aspect of the femoral head and calcar

Materials and MethodsMaterials and Methods

# Medial aspect of the femoral head and calcar are minimally affected during disease process

Second stepSecond step • • FFemoral shaft and neck axisemoral shaft and neck axis • • The most superolateral and inferomedial point of femoral head The most superolateral and inferomedial point of femoral head • • Base lineBase line

Materials and MethodsMaterials and Methods

a

a′

A

A’

Materials and MethodsMaterials and Methods

a

a′

A

A’

Third stepThird step • • DDivide the base line into thirds ivide the base line into thirds • • Draw lines parallel to the femoral neck axis through 2 points Draw lines parallel to the femoral neck axis through 2 points

‖‖

‖

‖

‖‖b

b′

B

B’

Materials and MethodsMaterials and Methods

a

a′

A

A’

b

b′

B

B’

Final stepFinal step • • BBest fitting circle passing a′(A′) and b′(B′) placing the centerest 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′)of circle to the median of the line connecting a′(A′) and b′(B′)

# Definition of circle : The set of all points in a plane# Definition of circle : The set of all points in a plane whichwhich are equidistant from a given point (center of circle)are equidistant from a given point (center of circle)

┐ ┐

r R

RLT

Materials and MethodsMaterials and Methods

a

a′

A

A’

b

b′

B

B’

The ratio of maximal epiphyseal height (MEH) The ratio of maximal epiphyseal height (MEH) to the waist of the femoral head to the waist of the femoral head

• • Subchondral bone instead of articular cartilage (in MRI) Subchondral bone instead of articular cartilage (in MRI)

W W

MEH

Differential coefficient Differential coefficient isisdecreased as the point ofdecreased as the point ofcontact moves toward middlecontact moves toward middleportion in ellipse portion in ellipse

Maximal epiphyseal heightMaximal epiphyseal heightrepresent more effectively therepresent more effectively thehead growth or roundness head growth or roundness ininthe middle thirdthe middle third

Materials and MethodsMaterials and Methods

Final data analysisFinal data analysis • • Relative change of RLT (%) = × 100 (%)Relative change of RLT (%) = × 100 (%)

Materials and MethodsMaterials and Methods

r – R

r

a

a′

A

A’

b

b′

B

B’

# Definition of circle : The set of all points in a plane# Definition of circle : The set of all points in a plane whichwhich are equidistant from a given point (center of circle)are equidistant from a given point (center of circle)

┐ ┐

r R

RLT

Final data analysisFinal data analysis • • Relative change of MEH (%) = × 100 (%)Relative change of MEH (%) = × 100 (%)

Materials and MethodsMaterials and Methods

m – M

m

a

a′

A

A’

b

b′

B

B’

W W

MEH

D. Nelson, M. Zenios, K. Ward et al, JBJS 2007

r R

r’ R’

ROC in lateral third : rROC in medial third : r’The ratio of ROC (RML) : r’/r

ROC in lateral third : RROC in medial third : R’The ratio of ROC (RML) : R’/R

* ROC : Radius Of Circle

Amount of collapse in lateral portion of deformed femoral head# RML = ROC in medial 1/3 / ROC in lateral 1/3 (Rm / RL)

Final Stulberg classificationFinal Stulberg classification

Materials and MethodsMaterials and Methods

ResultsResults

Measurements

Group 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)

Total 48

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 4.5 0.76 → 0.90 (0.14)

Operative 4 10.2 3.5 0.74 → 0.82 (0.08)

Total 23

Chron. Age > 8.0 at disease onset

Nonoperative 2 5.5 4.4 0.82 → 0.88 (0.06)

Operative 3 16.7 5.6 0.73 → 0.84 (0.11)

Total 5

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)

Total 11

Chron. Age > 8.0 at disease onset

Nonoperative 2 13.2 4.0 0.69 → 0.78 (0.09)

Operative 7 27.3 9.4 0.61 → 0.80 (0.19)

Total 9

2020

Comparison of each value : p < 0.05 by paired t-test

0.76

0.59

0.12

0.19

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Pillar B Pillar C

Mea

n v

alue

s (R

ML

)

Groups

Mean changes of head roundness (RML)

Residual stage

Fragmentation or early reossification stage

Final Stulberg classificationsFinal Stulberg classifications

ResultsResults

II III

Group 1 (n=25) 10 15

Group 2 (n=23) 4 19

p = 0.09 by Pearson chi-square test

ConclusionsConclusions

ConclusionsConclusions

Femoral head roundness was improvedFemoral head roundness was improved

with ossification of the affected hipwith ossification of the affected hip

More round femoral head can be expected More round femoral head can be expected

in the lateral pillar B hips than pillar Cin the lateral pillar B hips than pillar C

ConclusionsConclusions

However, VFO performed in theHowever, VFO performed in the

fragmentation stage of lateral pillar C hips fragmentation stage of lateral pillar C hips

leads to greater improvement in femoralleads to greater improvement in femoral

head roundness than does non-surgicalhead roundness than does non-surgical

treatment of lateral pillar B hipstreatment of lateral pillar B hips

Case 1Case 1M/7+3M/7+3

Group 1Group 1

RMTRMT

5.08 5.02 1%

RLTRLT

8.04 6.00 25%

MEHMEH

1.68/4.75 1.78/4.76 6%

RMLRML

5.08/8.04 = 0.63 5.02/6.00 = 0.84 0.21

Case 2Case 2M/10+0M/10+0

Group 2Group 2

RMTRMT

5.80 5.30 9%

RLTRLT

9.29 6.34 32%

MEHMEH

1.80 2.10 17%

RMLRML

5.80/9.29 = 0.62 5.30/6.34 = 0.84 0.22

Thank you for your attention !Thank you for your attention !