improvement of femoral head roundness after valgus femoral osteotomy in legg-calve-perthes disease...

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

    Pediatric Orthopaedic UnitDepartment of Orthopaedic SurgeryPusan National University HospitalHui Taek Kim, MD and Seong Ho Bae, MD

  • IntroductionDeformation 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

  • IntroductionContainment 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

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

  • PurposeTo quantify the changes of femoral head roundness after valgus femoral osteotomy Using new measuring method

  • 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)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 yearsMaterials 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 ()

    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) Materials and Methods

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

  • Measuring methodsMaterials and Methods

  • Most clear image Entire proximal femur Fragmentation stage in MRI / residual stage in AP radiograph

    Image-analysis software Adobe Photoshop Microsoft Power PointMaterials 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 Materials and Methods

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

  • Second step Femoral shaft and neck axis The most superolateral and inferomedial point of femoral head Base lineMaterials and MethodsaaAA

  • Materials and MethodsaaAAThird step Divide the base line into thirds Draw lines parallel to the femoral neck axis through 2 points bbBB

  • Materials and MethodsaaAAbbBBFinal step 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)# Definition of circle : The set of all points in a plane which are equidistant from a given point (center of circle)RLT

  • Materials and MethodsaaAAbbBBThe ratio of maximal epiphyseal height (MEH) to the waist of the femoral head Subchondral bone instead of articular cartilage (in MRI) WWMEH

  • Differential coefficient isdecreased as the point ofcontact moves toward middleportion in ellipse Maximal epiphyseal heightrepresent more effectively thehead growth or roundness inthe middle thirdMaterials and Methods

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

    Materials and Methodsr R

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

  • Final data analysis Relative change of MEH (%) = 100 (%)Materials and Methodsm M

    maaAAbbBBWWMEH

  • D. Nelson, M. Zenios, K. Ward et al, JBJS 2007ROC in lateral third : rROC in medial third : rThe ratio of ROC (RML) : r/rROC in lateral third : RROC in medial third : RThe ratio of ROC (RML) : R/R* ROC : Radius Of CircleAmount of collapse in lateral portion of deformed femoral head# RML = ROC in medial 1/3 / ROC in lateral 1/3 (Rm / RL)

  • Final Stulberg classificationMaterials and Methods

  • Results

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

    MeasurementsGroupTotalRLT (%)MEH (%)RML ()All hips Nonoperative2513.23.90.74 0.84 (0.10) Operative2321.4 7.80.65 0.81 (0.16) Total48

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

    MeasurementsGroupTotalRLT (%)MEH (%)RML ()

    Lateral pillar group B2815.04.50.76 0.88 (0.12) Chron. Age 8.0 at disease onset Nonoperative1916.84.50.76 0.90 (0.14) Operative410.23.50.74 0.82 (0.08) Total23 Chron. Age > 8.0 at disease onset Nonoperative25.54.40.82 0.88 (0.06) Operative316.75.60.73 0.84 (0.11) Total5

  • 2020Comparison of each value : p < 0.05 by paired t-test

    MeasurementsGroupTotalRLT (%)MEH (%)RML ()

    Lateral pillar group C26.69.60.59 0.78 (0.19)

    Chron. Age 8.0 at disease onset Nonoperative217.42.70.70 0.81 (0.11) Operative931.212.50.53 0.76 (0.23) Total11 Chron. Age > 8.0 at disease onset Nonoperative213.24.00.69 0.78 (0.09) Operative727.39.40.61 0.80 (0.19) Total9

  • Chart1

    0.760.12

    0.590.19

    Fragmentation or early reossification stage

    Residual stage

    Groups

    Mean values (RML)

    Mean changes of head roundness (RML)

    Sheet1

    Fragmentation or early reossification stageResidual stage

    Pillar B0.760.12

    Pillar C0.590.19

    .

    Sheet2

  • Final Stulberg classifications Resultsp = 0.09 by Pearson chi-square test

    IIIIIGroup 1 (n=25)1015Group 2 (n=23)419

  • Conclusions

  • ConclusionsFemoral 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

  • ConclusionsHowever, 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

  • Case 1M/7+3Group 1

  • RMT5.085.021%

  • RLT8.046.0025%

  • MEH1.68/4.751.78/4.766%

  • RML5.08/8.04 = 0.635.02/6.00 = 0.840.21

  • Case 2M/10+0Group 2

  • RMT5.805.309%

  • RLT9.296.3432%

  • MEH1.802.1017%

  • RML5.80/9.29 = 0.625.30/6.34 = 0.840.22

  • Thank you for your attention !