Growth rate after limb deformity correction by the Ilizarov method with or without knee joint distraction

Figures & data

Table 1. Characteristics of 30 patients prior to limb deformity correction, and description of their deformities

Patient Sex		Age (years)	Location ^a	Diagnosis	Concomitant deformities and factors ^b	LLD ^c (cm)	rLLD ^d (%)	Angulation and rotation (degrees)	Dahl type
1	F	9	T	growth arrest after osteo myelitis, proximal tibia	3,5,10,17,21	7.0	20	30 varus	4
2	M	12	T	congenital short tibia	3,9,24,24	5.6	16		4
3	F	9	T	femur-fibula-ulna syndrome	2,3,7,14,15,17	7.5	26	54 varus	5
4	F	6	T	femur-fibula-ulna syndrome	2,3,7,8,14,15,17,18,21	8.9	20	35 valgus, 45 int. rotation	5
5	F	9	T	congenital short tibia	6,8	6.1	23		3
6	F	9	F	congenital short femur	14	5.1	16		2
7	M	14	F+T	polyostotic fibrous dysplasia	2,3,12,18,21,22,22,26,26	17.9	20	45 int. rotation tibia	5
8	F	9	F	growth arrest after arthritis of the hip	1,3	4.3	13		2
9	F	11	T	child abuse, ischiac nerve lesion	11	4.5	20		2
10	M	14	T	congenital short tibia	3,7,8,9,15	4.9	15		3
11	M	8	F+T	congenital short femur + tibia	14	7.3	12		3
12	M	15	F	congenital short femur	17	4.5	9	20 valgus	1
13	F	13	F	growth arrest after fracture distal femur	2,4,10,17,18,21,21	4.4	11	10 valgus, 15 int. rotation	5
14	M	11	F	growth arrest after arthritis of the hip	1,2,17,21,21,22	4.2	11	20 procurvatum	4
15	F	7	T	congenital short tibia	5,7,8,15,22,23,24	7.8	26		5
16	M	6	T	congenital short tibia	2,5,7,8,14,15,22,23	8.4	36		5
17	M	11	T	Ollier's disease	2,17,18	4.6	16	35 ext. rotation, 18 retrocurvatum	4
18	M	8	F	congenital short femur	19,22,25	5.4	18		3
19	F	9	F	growth arrest after arthritis of the hip	17	2.9	8	20 valgus	2
20	F	10	T	congenital short tibia	3,17	5.4	18	14 valgus	3
21	M	14	T	growth arrest after arthritis of the knee	17	3.9	7	20 valgus	2
22	M	7	T	congenital short tibia	3,7,14	8.9	33		4
23	F	6	T	congenital short tibia	3,7,8,14,17	10.2	42	25 procurvatum	5
24	F	8	T	congenital short tibia	7,13,16,17,21,21,22,24	1.7	6	30 procurvation	4
25	M	11	F+T	congenital short femur +tibia	14	7.7	10		3
26	F	11	F	growth arrest after arthritis of the hip	2,3,14,20	14.8	38		5
27	M	7	T	femur-fibula-ulna syndrome	2,3,7,8,14,15,22,23	6.2	29		5
28	F	10	T	Ollier's disease	3,7,15,17,21	2.6	9	35 valgus	2
29	F	13	T	congenital short tibia		3.4	8		1
30	M	9	F	congenital short femur	7,15,17	1.9	7	30 valgus

^a Location: F – femur; T – tibia.

^b Concomitant deformities and factors according to Dahl et al. (1994): 1 contracture hip, 2 contracture knee, 3 equinus, 4 ankylosis knee, 5 ankylosis ankle, 6 tarsal coalition, 7 fibular hypo-/aplasia, 8 absence of foot rays, 9 clubfoot, 10 dislocated patella, 11 ischiatic nerve lesion, 12 femoral pseudarthrosis, 13 tibial pseudarthrosis, 14 ACL aplasia, 15 ball and socket ankle, 16 active infection, 17 angulation deformity, 18 torsion deformity, 19 hip dysplasia, 20 lateral femoral condyle dysplasia, 21 previous lengthening procedure, 22 previous correction osteotomy, 23 previous resection fibular fibrous band, 24 previous correction equinus deformity, 25 other previous soft tissue corrections, 26 simultaneous correction in two bone segments.

^c LLD (cm): leg-length discrepancy (LLD) in centimeters.

^d rLLD (%): relative leg-length discrepancy; see text for the definition.

^e Dahl (type): see text for definition of the Dahl types regarding the severity of the deformity.

Graphical representation of the statistical principle of a positive and negative intercept as the result of an intervention in a shortened leg, compared with the normal leg. The length of the normal leg is represented on the x-axis. The length of the shortened leg is represented on the y-axis. The reference line represents the relationship between the lengths of the normal and shortened legs. The relationship between the lengths of normal and shortened legs may change, e.g. by surgical intervention. For better graphical representation, the gain in length from the lengthening procedure is deducted from the length of the shortened leg after the intervention. When the line of proportionate growth shows a changed slope after the intervention, as compared to the reference line, and when this new line has a negative intercept with the y-axis, it represents increased growth of the shortened leg compared to the normal leg. When this new line has a positive intercept with the y-axis, it represents decreased growth of the shortened leg compared to the normal leg.

Table 2. The results of limb deformity correction in 30 patients

Pat	Frame ^a	Ost. site ^b	Consol. ^c (weeks)	Paley complications ^d			Angulation	Gain (cm)	Gain (%)	LI ^e (mo/cm)	LLD ^f (cm)	rLLD ^g (%)	F-U ^h (mo)	ΔLLD po ^i (cm)	Growth rate ^j
				problem	obstacle	real
1	3	2	42	8				6	17	1.7	13	37	73	3	–
2	2	2	30	4,8				6	17	0.8	0.6	2	60	0.1	+
3	3	2	38	8	2	3,9,9	50° varus	6.5	23	1.4	4.6	18	40	4.5	–
4	3	3	22	8	1,6			5	11	1.0	7.8	30	103	0	+
5	2	2	23		8			6	23	0.8	0	0	97	2	+
6	1	1	26	1,8		10		5.5	17	1.0	1.7	4	45	3.3	–
7	3	2	19	4,8,8		9		6	7	1.1	14	15	41	6.4	–
8	1	1	28	7,8		3	14° valgus	5	15	1.2	0.7	2	77	-0.3	+
9	2	2	26	8				4	18	1.5	1.7	5	47	0.5	o
10	2	2	28	4				5.5	17	1.2	3.8	9	33	-0.7	+
11	3	3	31		9	9		8	13	0.9	-0.7	-1	109	0.6	+
12	1	1	23	8				4	8	1.3	0.5	1	28	0	+
13	3	1	32	7,8				4	10	1.9	1	2	24	0	+
14	3	1	27	8				5.5	14	1.1	0.5	1	72	1.5	–
15	2	2	29	8		6,9		4.5	15	1.6	4.7	14	83	-0.7	+
16	3	2	25	8				6	26	1.0	2.5	10	32	2.3	o
17	2	2	8	7,8		3,4,6	16° retrocurvatum	1	3	2.0	4.4	15	64	5.9	–
18	1	1	21	8				5	17	1.0	-0.5	-1	99	3.5	–
19	1	1	22	7	8	3	20° procurvatum	2	6	2.0	2	5	60	3.1	–
20	2	2	32	8				5	17	1.5	0.5	2	55	2	o
21	2	2	20	8		6		2	4	2.5	2.7	7	24	0.1	+
22	3	2	27	8				6	22	1.0	4	14	63	0.4	+
23	3	2	25					6	25	1.0	4.2	12	96	1.7	+
24	3	3	11	8				1	4	2.5	0.9	3	65	4.3	–
25	3	3	30	8	8	10		8	10	1.0	0	0	66	0.6	+
26	3	1	30	8				6	15	1.1	8.4	21	48	2.1	+
27	3	2	36	8				6	28	1.0	0	0	62	0.5	+
28	2	2	31			3,6	10° valgus	2	7	3.0	0	0	102	0	o
29	2	2	33			9		3	7	2.6	1	2	49	1	+
30	1	1	28					2	7	3.3	0	0	28	0	o

^a Frame: configuration of Ilizarov frame: 1 femur, 2 tibia, 3 femur and tibia.

^b Ost. site: osteotomy site: 1 femur, 2 tibia, 3 femur and tibia.

^c Consol.: consolidation time in weeks, duration of correction and consolidation, total period in frame.

^d Paley complications: classification of complications (Paley 1990): problems (difficulties resolved without operation), obstacles (difficulties resolved with operative intervention), minor and major complications (all intraoperative injuries; difficulties not resolved before the end of the treatment, minor complication if resolved with nonoperative treatment, major complication if operative treatment is required): 1 muscle contracture, 2 joint luxation, 3 axial deviation (minor < 5º, major > 5º), 4 neurological injury (peroneal nerve), 5 vascular injury, 6 premature consolidation, 7 delayed consolidation, 8 pin-site problems, infections, 9 refracture, 10 joint stiffness.

^e LI: lengthening index; period in frame (months) divided by length gained (cm).

^f LLD: residual leg length discrepancy in cm.

^g rLLD: residual relative leg length discrepancy, see text for the definition of relative LLD.

^h F-U: follow-up in months after initiation of treatment.

ⁱ ΔLLD po: difference of LLD from first and last leg length measurement in cm.

^j Growth rate: + stimulated; o neutral; – decreased growth rate.

Table 3. Results of statistical testing using a repeated-measures ANOVA mixed model: significance of the possible treatment factors that may influence the pattern of growth of the limb. The results of significant factors are considered in Table 4

	P-value
Frame configuration, on the whole leg	0.003
Location of osteotomy, on the whole leg	1.0
Cause of deformity, on the whole leg	0.8
Location of osteotomy, on the femur	0.09
Location of osteotomy, on the tibia	0.04

Table 4A. Results of statistical testing using a repeated-measures ANOVA mixed model. The frame configuration has a significant effect on growth pattern. The negative value of a knee-bridging intercept indicates a decreasing proportionate leg length discrepancy, i.e. growth stimulation

Frame configuration: p = 0.003		95% CI
Intercept, femoral frame	3.1	(-2.0–8.2)
Intercept, tibial frame	3.3	(-1.5–8.1)
Intercept, knee-bridging frame ^a	-1.7	(-6.1–2.6)

^aThis category differs significantly from the other two categories

Table 4B. Results of statistical testing using a repeated-measures ANOVA mixed model. The location of the osteotomy for the lengthening procedure has a significant effect on the growth pattern. The positive intercept indicates an increasing proportionate leg length discrepancy, i.e. inhibited growth for all types of osteotomy. The tibial osteotomy has significantly less inhibitory effect than other types of osteotomy

Location of osteotomy on the tibia: p = 0.04		95% CI
Intercept, femoral osteotomy	4.0	(0.5–7.6)
Intercept, tibial osteotomy ^a	0.7	(-9.9–11.0)
Intercept, osteotomy of femur and tibia	3.6	(-2.6–4.1)

^aThis category differs significantly from the other two categories.

Dahl MT, Gulli B, Berg T. Complications of limb lengthening. A learning curve. Clin Orthop 1994, 301: 10–8

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