Reconstructive hip surgery in children with cerebral palsy: factors influencing risk of femoral head avascular necrosis

The incidence of avascular necrosis in children with cerebral palsy after hip containment surgery

PURPOSE

To establish the rate of avascular necrosis after hip reconstruction surgery in children with cerebral palsy and to identify risk factors that influence the development of avascular necrosis in this population.

METHODS

An institutional review board-approved retrospective review was conducted on children with cerebral palsy who underwent hip containment surgery at a single institution. Radiographs were evaluated at three time points. The Reimer's migration percentage, neck shaft angle, epiphyseal shaft angle, acetabular index, center edge angle, and acetabular angle were measured. The presence of avascular necrosis was evaluated and graded by the Bucholz/Ogden and the Kalamchi/MacEwen classification systems. Multivariate logistic regression was performed to identify risk factors associated with the development of avascular necrosis.

RESULTS

A total of 154 children with cerebral palsy underwent hip containment surgery on 223 hips. Twenty-nine children (18.8%) underwent both pelvic and femoral procedures; 36 children (23.4%) had only femoral procedures; 47 children (30.5%) had femoral and soft tissue; and 42 children (27.3%) had pelvic, femoral, and soft tissue procedures. Using the Bucholz and Ogden or the Kalamchi classifications, the rate of avascular necrosis was 24.7% (38/154). Of the variables evaluated, preoperative Reimers was found to be significant predictors of avascular necrosis. The rate of avascular necrosis was 26.7% for Gross Motor Functional Classification System level III, 24.1% for Gross Motor Functional Classification System level IV, and 27.3% for Gross Motor Functional Classification System level V.

CONCLUSION

The overall rate of avascular necrosis in children undergoing hip containment surgery was 26.7%. Together, age at surgery, open reduction, previous surgery, preoperative Reimers, and estimated blood loss contributed to the development of postoperative avascular necrosis; however, only preoperative Reimers significantly contributed to the development of avascular necrosis in children with cerebral palsy undergoing hip containment procedures.

Fate of hips complicated by avascular necrosis of the femoral head following reconstructive surgery in nonambulatory patients with cerebral palsy

The purpose of this study was to evaluate the influence of avascular necrosis of the femoral head (AVN) following hip reconstructions on the future hip development of cerebral palsy (CP) patients. A retrospective study of 394 hips in 205 nonambulatory patients with spastic CP who underwent reconstructive hip surgery was performed. The mean age at surgery was 7.3 ± 2.4 years. The mean follow-up duration was 5.6 ± 2.7 years, and the mean age at the latest follow-up was 12.8 ± 3.4 years. AVN was classified in terms of its severity and location. Femoral head remodelling was assessed by the spherical index and the Mose circle. An unsatisfactory radiological outcome was defined as having a migration percentage of more than 30% at the final follow-up. AVN was observed in 169 (42.9%) hips. Older age at the time of surgery, higher preoperative migration percentage, and open reduction procedures were predictors for the development of AVN. Hips with AVN confined to the lateral epiphysis, and AVN involving the entire epiphysis with preserved height experienced successful remodelling. 27 (65.9%) of the 41 hips with unsatisfactory outcomes experienced AVN. Younger age, higher postoperative migration percentage, and occurrence of AVN were related to unsatisfactory outcomes. The highest incidence of failed remodelling and unsatisfactory outcomes were observed in hips with entire epiphyseal involvement and more than 50% loss of its height. AVN following hip reconstructions is not necessarily associated with poor hip development, however, depending on the severity and location, it is a prognostic factor for unsatisfactory radiological outcomes.

Can Over-containment Prevent Recurrence in Children With Cerebral Palsy and Hip Dysplasia Undergoing Hip Reconstruction?

INTRODUCTION

Hip reconstruction is often necessary in children with cerebral palsy (CP) but is associated with high failure rates. Over-containment deeply seats the hip within the acetabulum at the time surgical reconstruction. The goal of this study is to evaluate the effect of over-containment on radiographic outcomes and failure rates in children with CP undergoing hip reconstruction.

METHODS

This study is a retrospective chart review of children with CP that underwent hip reconstruction between 2010 and 2019 with at least 2 years of radiographic follow-up. Migration percentage (MP), acetabular index (AI), and neck shaft angle (NSA) were recorded preoperatively, postoperatively and throughout follow-up. Failures were defined as a MP at latest follow-up ≥30% or need for revision hip reconstruction. Hips were divided into groups based on postoperative MP-group 1 (over-containment group) had a MP≤0% and group 2 had an MP>0%. Radiographic parameters and failure rates were compared across Gross Motor Functional Classification Score (GMFCS) level, age at the time of surgery, and degree of preoperative subluxation.

RESULTS

A cohort of 108 patients (197 hips) with an average age of 7.3±3.2 years met inclusion criteria with an average follow-up of 49.6 months (range: 24 to 118 mo). There were 147 hips in group 1 and 50 hips in group 2. At latest follow-up, group 1 demonstrated lower MP, AI, and NSA in comparison to group 2. The overall failure rate in our cohort was 8.1% (16 hips). Failure rates trended lowest in hips that were over-contained (6.1% v. 14.0%) although not statistically significant. Over-containment resulted in significantly lower failure rates in GMFCS IV/V hips, children under age 6 at the time of surgery and those with a higher degree of preoperative hip displacement (MP>50%).

CONCLUSIONS

Over-containment at the time of hip reconstruction can positively affect radiographic outcomes and failure rates in children with CP. Over-containment should be considered in hips at high risk of failure, especially non ambulatory children with significant hip subluxation at an early age.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Blood loss in hip reconstructive surgery in children with cerebral palsy: when do I need to be prepared for blood transfusion?

The hip is the second most common joint involved in pediatric patients with cerebral palsy (CP). Hip reconstructive procedures are performed to improve function and comfort level. Blood loss can occur leading to blood transfusion in close to 1/3 of children with CP undergoing hip reconstruction. The purpose of this study was to report the rate and risk factors for blood transfusion after hip reconstruction in a large cohort of children with CP. We conducted a retrospective chart review of pediatric patients at our tertiary referral children's hospital who underwent reconstructive hip osteotomy over an 8-year period. Binary logistic regression was employed to compare and model differences in transfusion between age greater than 4 or 6 years and the number of osteotomies. A total of 180 patients met our inclusion criteria. Thirty-seven patients (20.6%) received blood transfusion. Incidence of transfusion increased as number of osteotomies increased from 1 to 4 (3.7%, 7.3%, 34.0%, 58.3%, respectively). We did not find a significant effect of age greater than 4 or 6 years on the rate of blood transfusion (P = 0.676 and P = 0.323, respectively). The number of osteotomies was a significant factor in the rate of blood transfusion in both models (P < 0.001). Number of osteotomies and not age was a significant risk factor in the rate of blood transfusion. This data can help the orthopedic surgeons in preoperative planning for the possibility of blood transfusion in these patients.