Femoral and pelvic osteotomies for severe hip displacement in nonambulatory children with cerebral palsy: a prospective population-based study of 31 patients with 7 years’ follow-up

Figures & data

Table 1. Association between types of osteotomy and various clinical and preoperative radiographic variables

Variables	FVO ^a	Combined osteotomies ^b	p-value
Girls	7	4	0.07
Boys	6	14
GMFCS level IV	4	4	0.6
GMFCS level V	9	14
Primary operation	12	11	0.05
Secondary operation	1	7
Unilateral operation	7	16	0.03
Bilateral operation	6	2
Baclofen pump	2	9	0.05
No baclofen pump	11	9
Hip pain preoperatively	5	5	0.5
No hip pain preoperatively	8	13
Age at surgery (SD)	5.2 (1.7)	6.7 (1.7)	0.02
Migration percentage (SD)
preoperative	63 (15)	75 (18)	0.02
1 year postoperatively	27 (14)	19 (12)	0.09
reduction	36 (24)	56 (21)	0.008
Acetabular index preoperative (SD)	30 (3.6)	30 (3.3)	0.8
Pelvic obliquity preoperative (SD)	3.1 (3.2)	4.6 (4.9)	0.3

a Femoral varus osteotomy.

b Femoral varus osteotomy and pelvic osteotomy.

GMFCS = gross motor function classification system.

SD = standard deviation.

Figure 1. A. Preoperative radiograph of a boy, aged 7.0 years and GMFCS level V, with severe subluxation of his right hip (MP 67%). B. 1 day after femoral osteotomy (varus, derotation and shortening), pelvic osteotomy, and bilateral soft tissue releases, showing good femoral head coverage bilaterally. The cortical bone segment removed from femur has been used as autograft in the open wedge of the pelvic osteotomy. C. 7.4 years postoperatively, at an age of 14.4 years, showing satisfactory femoral head coverage bilaterally, MP 19% (right hip) and 0% (left hip)

Figure 2. A. Preoperative radiograph of a girl, aged 8.1 years and GMFCS level V, with severe subluxation of her left hip (MP 74%). B. 6 weeks after femoral and pelvic osteotomies of the left hip and bilateral soft tissue releases, showing good femoral head coverage. C. 2.9 years postoperatively (age 11.0 years), showing relapse of subluxation of her left hip (MP 51%).

Table 2. Potential prognostic factors for poor radiographic outcome in 31 patients, estimated as relative risks (RR) for failure, using univariable Poisson loglinear regression

Variables	Outcome		Statistical analysis RR (95% CI)	p-value
	Good	Failure
Girls	7	4	Reference
Boys	15	5	0.7 (0.2–2.6)	0.6
GMFCS, level IV	8	0	Reference
GMFCS, level V^a	14	9	OR 6.3 (0.8–∞)	0.08
Primary operation	15	8	Reference
Secondary operation	7	1	0.4 (0.1–2.9)	0.3
Unilateral operation	18	5	Reference
Bilateral operation	4	4	2.3 (0.6–8.6)	0.2
No pain preoperatively	15	6	Reference
Pain preoperatively	7	3	1.1 (0.3–4.2)	0.9
Combined osteotomies	15	3	Reference
Femoral osteotomies	7	6	2.8 (0.7–11.1)	0.2
Age (SD)	6.4 (1.9)	5.4 (1.8)	0.8 (0.6–1.2)	0.3
Migration percentage (SD)
preoperative	72 (19)	69 (12)	1.0 (0.96–1.03)	0.8
1 year postoperatively	21 (11)	35 (14)	1.05 (1.01–-1.1)	0.03
Acetabular index preop. (SD)	30 (3.0)	31 (3.8)	1.08 (0.88–1.3)	0.5
Pelvic obliquity preop. (SD)	3.4 (3.7)	5.9 (5.8)	1.1 (0.94–1.3)	0.3

For abbreviations, see Table 1.

a Exact logistic regression was used because one group contained the value “0.”

Table 3. Multivariable analysis of odds ratios for poor outcome, including variables with a p-value < 0.2 in univariable analysis, using multivariable exact logistic regression

Variables	Odds ratio	95% CI	p-value
GMFCS, level V	15	1.4–∞	0.02
Femoral osteotomy	5.4	0.5–237	0.2
Migration percentage 1 year postop.	1.1	1.0–1.4	0.01

For abbreviations, see Table 1. CI = confidence interval.

Table 4. Migration percentage pre- and postoperatively (mean values with 95% confidence intervals (CI) in parentheses) of all 39 hips and comparison between hips with good and poor radiographic outcome

Migration percentage	All hips	Outcome		Difference		p-value ^a
		Good	Poor	Mean	(95% CI)
Preoperative	69 (63–75)	69 (62–76)	68 (60–77)	0.8	(–12 to 14)	0.9
Primary correction^b	46 (38–54)	49 (39–59)	36 (22–49)	13	(–4 to 31)	0.1
1 year postop	23 (19–28)	20 (16–24)	33 (22–43)	– 13	(–22 to –4)	0.008
3 years postop	30 (24–36)	25 (21–30)	47 (27–67)	–22	(–34 to –10)	0.04
5 years postop	33 (24–43)	25 (18–33)	58 (32–83)	–32	(–49 to –15)	0.001
Progression per year
preoperative^c	15 (11–19)	14 (10–19)	16 (6–25)	–1.0	(–11 to 9)	0.8
postoperative	2.9 (1–5)	0.7 (–0.4–1.8)	10 (5–15)	–9.5	(–15 to –4)	0.002
Contralateral side
preoperative	29 (24–34)
last follow-up	26 (16–35)

a Student’s t-test.

b Difference between migration percentage preoperative and 1 year postoperatively.

c Progression of preoperatively was calculated during a mean period of 2.9 years (0.8–5.8).

Figure 3. A. Preoperative radiograph of a girl, aged 5.7 years and GMFCS level V, with complete dislocation of her right hip (MP 100%) and subluxation of her left hip (MP 51%). B. 14 months after femoral and pelvic osteotomies of the right hip and bilateral soft tissue releases, showing slight subluxation of both hips (MP right hip 36% and left hip 37%). C. 7.3 years postoperatively (age 13.0 years), showing good position of right hip and deterioration of left hip (MP 64%).

Figure 4. Kaplan–Meier survival plot (% survival with 95% confidence intervals) in all 39 hips, with time to failure (reoperation or MP ≥ 50%) as “survival”.