Response to the Letter to Editor regarding: “High effectiveness of multilevel orthopedic surgery and guided growth in spastic hemiplegia children”

Dear Editor,

We are thankful to the authors of the letter for their interest in our study and for their insightful comments. We would like to take this opportunity to clarify several methodological points and our approaches in this dual-sided surgery.

1. We do agree with the authors that the absence of a matched control group is a limitation of our study. There are two interrelated explanations for this. First, the instrumental analysis method has been available at our institution since 2017. Second, there are publications (mentioned in the article) clearly demonstrating the benefits of correcting lower limb length inequality in children with spastic hemiplegia in terms of improving kinetic and kinematic gait parameters. Therefore, patients were offered an approach that addressed the orthopedic components of the pathology, intervening on both limbs for the indications outlined in the article. Thus, we have no series of unilateral cerebral palsy patients having a leg length discrepancy but who would undergo surgery only on the involved limb. We believe this approach reduces the medical burden on children, and it was also the choice of their families. In addition, it would be worth pointing out that while a prospective randomized controlled trial may represent the “gold standard” it would simply be impractical and bordering on the impossible to plan and carry out in terms of accurately matched patient numbers in each arm for this group of conditions; the numbers required for statistical significance would be too great and also difficult to recruit.

2. We agree that the absence of patient-centered functional outcomes (Gross Motor Function Measure, quality of life assessment) and spine kinematics represents evident limits of the study. We would like to emphasize that those limitations have already been mentioned in our article. We hope this drawback of the study will be overcome and clarified by colleagues in further research.

3. Regarding bone age, we mentioned in the article that the actual interpretation of this parameter remains quite controversial. Erickson and Loder ¹ demonstrated no difference between chronological and bone age for patients with right or left hemiplegia and found no necessity to obtain radiographs of both hands in children with spastic hemiplegia to determine bone age. Lee et al. ² demonstrated that the bone age of the affected side is delayed in comparison to the unaffected one. Thus, there are no standardized and all-accepted approaches for this patient group to confidently use bone age in predicting segment growth and, even, for bone age interpretation. Furthermore, taking into consideration the reversibility of guided growth with eight plates on the longitudinal growth, we do not consider the prediction of the moment of epiphysiodesis based on bone age values to be crucial. As for the age of 12 years considered as a threshold for guided growth, it correlates with good results revealed in our study, and that is why we suggest performing a guided growth procedure before the age of 12 years to avoid length discrepancy undercorrection. Our findings of significant length discrepancy undercorrection in patients undergoing a guided growth procedure at an age greater than 12 are in agreement with outcomes reported by Corradin et al. ³ We revealed that in our patient population, in terms of factors such as race, the age of 12 has shown to be a reliable maximum; however, in other patient populations (such as Afro-Caribbean girls who mature earlier), this may not be the case, and as such, these centers could determine another threshold.

4. As for “normalization” emphasized by authors of the Letter, we do not use this term in the article. But we compare the kinetics and kinematics of the uninvolved limbs to our historical cohort of healthy children. Generally, correction of limb length discrepancy allows for avoiding greater muscular effort on the uninvolved leg, to prevent overuse injuries affecting the spine and longer limb.^4,5 The apparent reduction in compensatory hyperflexion and pelvic tilt reflects a shift toward decreased asymmetry between the limbs in children with spastic hemiplegia. It is evident that true symmetry cannot be achieved for children with spastic hemiplegia. However, the reduction in asymmetry improves gait parameters, including dorsiflexion on the involved side during the swing phase. We would like to reiterate that care must be taken not to overcorrect for the reasons that you have pointed out. And this did not occur in our series. Undoubtedly, long-term follow-up will allow us to determine whether these changes persist or regress with growth. However, the results published by Feldkamp in 1985 show that there is no increase in lower limb length discrepancy after the age of 8 in children with spastic hemiplegia, allowing us to speculate about the stability of dual-sided surgery results in long-term follow-up.

We believe that these clarifications will contribute to a better interpretation of our results, and we thank you for this opportunity for a constructive discussion.

Supplemental Material

sj-pdf-1-cho-10.1177_18632521251405152 – Supplemental material for Response to the Letter to Editor regarding: “High effectiveness of multilevel orthopedic surgery and guided growth in spastic hemiplegia children”

Supplemental material, sj-pdf-1-cho-10.1177_18632521251405152 for Response to the Letter to Editor regarding: “High effectiveness of multilevel orthopedic surgery and guided growth in spastic hemiplegia children” by Ulvi Mamedov, Tamara Dolganova, Orkhan Gatamov, Patrick Foster, Akhmed Tomov and Dmitry Popkov in Journal of Children's Orthopaedics