Sulis Bayu Sentono, M.D.†, Young Choi, M.D., Chin Youb Chung, M.D.,Soon-Sun Kwon, Ph.D.*, Kyoung Min Lee, M.D., Moon Seok Park, M.D.

†Department of Orthopaedic Surgery, Airlangga University Dr Soetomo Hospital, East Java, Indonesia. Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki, Korea. *Biomedical Research Institute,

Seoul National University Bundang Hospital, Kyungki, Korea

To assess progression of hip subluxation after femoral varization derotation osteotomy (FVDO) in patients with cerebral palsy using a Linear Mixed Model (LMM) application and determined factors influence it

Hip subluxation and dislocation in children with spasticity resulting from CP may cause serious problems for affected patient

Satisfactory short term results after FVDO or combined with Dega pelvic osteotomy for the treatment of hip subluxation and dislocation were reported by many authors

There are only a few long term studies reporting recurrency after FVDO or combined with Dega pelvic osteotomy after some periodic follow-up.

This study was a retrospective design

Patients with CP, who visited our hospital and underwent FVDO or combined with Dega pelvic osteotomy between from 2003 Jun. to 2012 Oct.

Investigate using X-ray in AP and Internal rotation view to assess Neck shaft angle(NSA), Head shaft angle (HAS), Migration percentage(MP) on pre-operative, immediate post operative and until last follow up

For each of GMFCS level, the value of measurements (NSA, HSA, MP) was adjusted by multiple factors by using a Linear Mixed Model (LMM) with gender as the fixed effects and follow-up time (years) effect, laterality (side of hip) and each subject as the random effect

Figure 1.:The angle between a line passing through the midway of the femoral shaft and another line connecting the femoral head center and midpoint of the femoral neck. The femoral head center was the center of best fitting outer circle of the femoral head.

Pre Operative

Post Operative

Figure 1.:The head shaft angle was the angle between line passing through the femoral shaft midway and another line perpendicular to the proximal femoral physis.

Pre Operative

Post Operative

Figure 1.:The migration percentage was calculated by dividing the amount of the femoral head lateral to the Perkin’s line (A) with the total width of the femoral head (B)

Pre Operative

Post Operative

There were one hundreds and fourty-four hips in 76 bilateral spastic CP patients All were bilateral CP type with GMFCS II-III / IV / V were 12 / 30 / 34, respectively All got bilateral FVDO in equal amount and 80 hips combined with Dega pelvic osteotomyThere were 57 males and 19 females with an average age at surgery was 8.5 ± 2.3 years (SD range from 4.5 to 16.5 years) and duration of follow up was 4.9±2.4 years

Parameters Values

Patient’s Information

No. of patients (M/F) 76(57/19)

CP type (Uni/Bi) 0/76

GMFCS (II-III/IV/V) 12/30/34

Age at surgery (yr) 8.5 ± 2.3

Follow up duration 4.9±2.4

Type of surgery

No. of Hips involved (Right/Left)

144(72/72)

FVDO (Right/Left) 144(72/72)

Dega PO (Right/Left) 80(45/35)

Parameters Values

Radiographic characteristics

NSA (°)

Preop 151.3±9.9

Immediate postop 129.0±14.6

Last F/U 129.1±15.3

HSA (°)

Preop 161.1±9.0

Immediate postop 141.9±13.9

Last F/U 142.9±14.7

MP (%)

Preop 53.7±30.0

Immediate postop 11.9±13.9

Last F/U 16.3±14.2

Estimate(%)

95% CI p

GMFCS II-III(Intercept) 12.4 -0.8 to 25.5 0.062

Gender Male 11.4 -2.5 to 25.3 0.106Side of hip Right -2.8 -8.3 to 2.7 0.285Follow up Year 0.7 -4.1 to 5.5 0.742

GMFCS IV(Intercept) 18.7 10.5 to 26.9 <0.001

Gender Male -7.1 -15.6 to 1.4 0.100Side of hip Right -0.8 -5.1 to 3.5 0.694Follow up Year 1.9 1.0 to 2.8 <0.001

GMFCS V(Intercept) 11.2 0.2 to 22.1 0.046

Gender Male -1.7 -13.2 to 9.8 0.774Side of hip Right -0.8 -6.2 to 4.7 0.777Follow up Year 3.5 1.3 to 5.8 0.003

There is progression of hip subluxation after FVDO in patients with CP particularly in patients non-ambulatory (GMFCS level IV and V)

Time of follow-up duration has main role in the occurency of this postulated

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