Paley et al developed a method for estimating the limb length discrepancy at skeletal maturity in a patient with a developmental injury to one lower extremity. The authors are from the Maryland Center for Limb Lengthening and Reconstruction in Baltimore.
Patient selection: pediatric patient with a developmental defect in 1 lower extremity resulting in a limb length discrepancy
Radiographic evaluation:
(1) 2 sets of radiographs are taken at least 6-12 months apart at a point after the start of the growth disturbance
(2) The radiographs are taken using the same method and with the same magnification.
current limb discrepancy =
= ((current length of normal limb) – (current length of shorter limb))
I =
= 1 – (((current length of short limb) - (previous length of short limb)) / ((current length of normal limb) - (previous length of normal limb)))
G =
= (length of normal limb) * ((multiplier for age and gender) – 1)
predicted discrepancy in lower limb length at maturity =
= (current limb length discrepancy) + (I * G)
Implementation Note: One question I have is whether the age of the child should be rounded up or down to the nearest decision point (for example 5 months rounded up to 6 months). This was not done for the current implementation.
Multiplier Table for Age and Gender
|
Years |
Months |
Boys |
Girls |
|---|---|---|---|
|
0 |
0 |
5.080 |
4.630 |
|
0 |
3 |
4.550 |
4.155 |
|
0 |
6 |
4.050 |
3.725 |
|
0 |
9 |
3.600 |
3.300 |
|
1 |
0 |
3.240 |
2.970 |
|
1 |
3 |
2.975 |
2.750 |
|
1 |
6 |
2.825 |
2.600 |
|
1 |
9 |
2.700 |
2.490 |
|
2 |
0 |
2.590 |
2.390 |
|
2 |
3 |
2.480 |
2.295 |
|
2 |
6 |
2.385 |
2.200 |
|
2 |
9 |
2.300 |
2.125 |
|
3 |
0 |
2.230 |
2.050 |
|
3 |
6 |
2.110 |
1.925 |
|
4 |
0 |
2.000 |
1.830 |
|
4 |
6 |
1.890 |
1.740 |
|
5 |
0 |
1.820 |
1.660 |
|
5 |
6 |
1.740 |
1.580 |
|
6 |
0 |
1.670 |
1.510 |
|
6 |
6 |
1.620 |
1.460 |
|
7 |
0 |
1.570 |
1.430 |
|
7 |
6 |
1.520 |
1.370 |
|
8 |
0 |
1.470 |
1.330 |
|
8 |
6 |
1.420 |
1.290 |
|
9 |
0 |
1.380 |
1.260 |
|
9 |
6 |
1.340 |
1.220 |
|
10 |
0 |
1.310 |
1.190 |
|
10 |
6 |
1.280 |
1.160 |
|
11 |
0 |
1.240 |
1.130 |
|
11 |
6 |
1.220 |
1.100 |
|
12 |
0 |
1.180 |
1.070 |
|
12 |
6 |
1.160 |
1.050 |
|
13 |
0 |
1.130 |
1.030 |
|
13 |
6 |
1.100 |
1.010 |
|
14 |
0 |
1.080 |
1.000 |
|
14 |
6 |
1.060 |
NA |
|
15 |
0 |
1.040 |
NA |
|
15 |
6 |
1.020 |
NA |
|
16 |
0 |
1.010 |
NA |
|
16 |
6 |
1.010 |
NA |
|
17 |
0 |
1.000 |
NA |
from Table V, page 1440 Paley et al (2000)
Specialty: Surgery, orthopedic
