1. Progression of Hip Subluxation after Femoral
Varization Osteotomy in Patients with Cerebral Palsy
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

2. Purpose
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

3. Background
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.

4. Methods 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

5. Methods
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

6. Operation Preop : FVDO + Dega

7. Operation Preop : FVDO + Dega

8. Methods (Measurement of NSA)
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

9. Methods (Measurement of HSA)
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

10. Methods (Measurement of MP)
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

11. Results
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 osteotomy
There 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

12. Results 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)
Dega PO (Right/Left)
80(45/35)

13. Results Parameters Values Radiographic characteristics NSA (°) Preop
151.3±9.9
Immediate postop
129.0±14.6
Last F/U
129.1±15.3
HSA (°)
161.1±9.0
141.9±13.9
142.9±14.7
MP (%)
53.7±30.0
11.9±13.9
16.3±14.2

14. 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
0.106
Side of hip
Right
-2.8
-8.3 to 2.7
0.285
Follow up
Year
0.7
-4.1 to 5.5
0.742
GMFCS IV
18.7
10.5 to 26.9
<0.001
-7.1
-15.6 to 1.4
0.100
-0.8
-5.1 to 3.5
0.694
1.9
1.0 to 2.8
GMFCS V
11.2
0.2 to 22.1
0.046
-1.7
-13.2 to 9.8
0.774
-6.2 to 4.7
0.777
3.5
1.3 to 5.8
0.003

15. Results

16. Results

17. Results

18. Conclusions
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

19. References
Park MS, Chung CY, Kwon DG, Sung KH, Choi IH, Lee KM. Prophylactic femoral varization osteotomy for contralateral stable hips in non-ambulant individuals with cerebral palsy undergoing hip surgery: decision analysis. Developmental Medicine & Child Neurology 2012;54(3):  
Lee KM, et all.Clinical Relevance of Valgus Deformity of Proximal Femur in Cerebral Palsy.J Pediatr Orthop 2010;10:
Oh CW, Presedo A, Dabney KW, Miller F.Factors affecting femoral varus osteotomy in cerebal palsy: A long-term result over 10 years. J Pediatr Orthop B 2007;16:23-30
Noonan KJ, Walker TL, Kayes KJ, Feinberg J. Varus derotation osteotomy for the treatment of hip subluxation and dislocation in cerebral palsy: Statistical analysis in 73 hips. J Pediatr Orthop B 2001; 10:
Gage JR, Carr C. The fate of the nonoperated hip in cerebral palsy. J Pediatr Orthop 1987;7:
Noonan KJ, Walker TL, Kayes KJ, Feinberg J.Effect of surgery on the nontreated hip in severe cerebral palsy. J Pediatr Orthop 2000;20:
Samilson RL, et al. Dislocation and subluxation of the hip in cerebral palsy. The Journal of Bone and Joint Surgery 1972;54-A :
Howard CB, McKibbin B, Williams LA, Mackie I. Factors affecting the incidence of hip dislocation in cerebral palsy. The Journal of Bone and Joint Surgery 1985; 67-B:
Laird NM, Ware JH. Random-effects models for longitudinal data. Biometrics. 1982;38:
Nguyen D, Sentrk D, Carrol R. Covariate-adjusted linear mixed effects model with an application to longitudinal data. J Nonparametr Stat.2008;20;
Settecerri JJ and Karol LA. Effectiveness of Femoral Varus Osteotomy in Patients with Cerebral Palsy. Journal of Pediatric Orthopaedics 2000; 20:776–780
Davids JR, Gibson TW, Pugh LI, and Hardin JW. Proximal femoral geometry before and after varus rotational osteotomy in children with cerebral palsy and neuromuscular hip dysplasia.J Pediatr Orthop 2013;33:182–189
Brunner R and Bauman JU. Long-term effects of intertrochanteric Varus-derotation osteotomy on femur and acetabulum in spastic cerebral palsy: An 11-to 18-year follow-up study. J Pediatr Orthop 1997;17(5):
Canavese F, Emara K, Sembrano JN, Bialik V, Aiona MD, Sussman MD. Varus Derotation Osteotomy for the Treatment of Hip Subluxation and Dislocation in GMFCS Level III to V Patients With Unilateral Hip Involvement. Follow-up at Skeletal Maturity. J Pediatr Orthop. 2010;30:357–364)