Abstract
Purpose
The correction obtained in the coronal plane knee deformity using guided growth was assessed in children with sick physes (Height<1SD of the normal children) to define the limits of this technique in sick physis
Methods
We retrospectively assessed deformity correction following guided growth using 8 plates in children with coronal plane deformity and metabolically abnormal physis- renal rickets in 6 and bone dysplasias (multiple epiphyseal dyspasia, spondyloepiphyseal dysplasia, metaphyseal dysplasia, mesomelic dysplasia, chondrodysplasia punctata) in 10 children aged 2 to 14 years. Lateral distal femoral angle(LDFA) and medial proximal tibia(MPTA) angles were serially assessed after eight plate application as a day care procedure. We noted correction achieved rate of correction, complications and additional surgical procedures. Fischer's exact test and multiple regression analysis was done to assess the effect of modifiers.
Results
Sixteen children mean aged 7.8 years (2–14 years) with 9 boys and seven girls were followed for a mean of 16.125 months. Deviations from normal MPTA(n=6) were a mean of 11.82(range 8.4–16.9) and from normal LDFA(n=15) a mean of 13.96 (range 5.7–35.1). Mean rate of correction was 0.8°(range 0.1–2.65) per month in dysplasia group and 1.09°(range 0.5–1.6)per month. Complete correction was achieved in 2 out of 6 in renal and 4 out of 10 in dysplasia group. Complication included backing out of screw (1), suboptimal screw placement (2) in dysplasia group and stiffness of the knee (1). Multiple regression analysis found sex, severity of deformity >15° and duration of follow up to be not significant, however, age less than 6 years had a significantly higher chance of deformity correction(P=0.001).
Conclusion
The rate of deformity correction with eight plates for guided growth is very variable even within the same patient in dysplasia group, chondrodyspalsia and SED having very slow correction rates. The deformities however correct completely before the age of 6 years irrespective of etiology. Bone dysplasias and metabolic causes require further study to understand their growth pattern and possibilities of relapse.
