Hip displacement in children with cerebral palsy: surveillance to surgery - a current concepts review

Abstract

This review brings together a multidisciplinary, multinational team of experts to discuss the current state of knowledge in the detection and treatment of hip displacement in cerebral palsy (CP), a global public health problem with a high disease burden. Though common themes are pervasive, different views are also represented, reflecting the confluence of traditional thinking regarding the aetiology and treatment of hip displacement in CP with emerging research that challenges these tried-and-true principles. The development of hip displacement is most closely related to gross motor function, with radiographic surveillance programs based on the Gross Motor Function Classification System (GMFCS), the goal being early detection and timely treatment. These treatments may include non-operative methods such as abduction bracing and Botulinum Neurotoxin A (BoNT-A), but outcomes research in this area has been variable in quality. This has contributed to conflicting opinions and limited consensus. Soft tissue lengthening of the hip adductors and flexors has traditionally been employed for younger patients, but population-based studies have shown decreased survivorship for this treatment when performed in isolation. Concerns with the identification of hip displacement in very young children are raised, noting that early reconstructive surgery has a high recurrence rate. This has prompted consideration of viable minimally invasive alternatives that may have better success rates in very young children with CP, or may at least delay the need for osteotomies. Recent reports have implicated the role of abnormal proximal femoral growth and secondary acetabular dysplasia as a primary cause of hip displacement, related to ambulatory status and abductor function. As such, guided growth of the proximal femur has emerged as a possible treatment that addresses this purported aetiology, with promising early results.

Keywords: Cerebral palsy; Hip displacement; Surveillance.

Figure 1

Clinical photo showing end-stage hip disease with gross cartilage loss.

Figure 2

Graph showing direct correlation between hip displacement and GMFCS (adapted from Soo et al. [3]).

Figure 3

Screening for hip displacement via standardized patient positioning and radiographic examination (adapted from Dobson et al. [19]).

Figure 4

Guided growth combined with STR was indicated for a 4-year-old patient (GMFCS IV) with bilateral MP 50%. Because of the young age, a percutaneous 4.5 mm cannulated screw is centred in the femoral physis in an AP view (A) and centred along the neck in a lateral view (B).

Figure 5

Hip abduction and knee extension are maintained by KAFOs and abduction wedge after STR.

Figure 6

(A) Preoperative radiograph of a 3-year-old patient with spastic quadriplegia (GMFCS III) and hip subluxation with Right MP 50% and Left MP 35%. (B) Ten years after isolated STR showing good outcome.

Figure 7

(A) Preoperative radiograph of a 4-year-old patient with spastic quadriplegia and dystonia. Hip abduction was 20° on the right side and 45° on the left side. (B) One year after STR and growth control on the right hip there was improvement of the morphology of the femoral head and acetabulum. Hip abduction was symmetric at 45°.

Figure 8

(A) Preoperative radiograph of 9-year-old child with Cerebral Palsy, GMFCS IV with progressive left hip subluxation. (B) Six-week postoperative radiograph demonstrating bilateral femoral osteotomies with cannulated blade plate and a pericapsular osteotomy of Dega on the left side using a wedge of bone from the femur.

Figure 9

(A) Preoperative radiograph of 18-year-old male, GMFCS III/IV with right hip pain and difficulty with weight bearing and activities of daily living. Note the asphericity of the femoral head and skeletal maturity indicating that remodeling of the femoral head here was not going to be substantive. (B) Intraoperative radiograph demonstrating the relationship between the trochanteric fragment and the femoral shaft. These pieces of bone are transfixed with #2 Fibrewire sutures. (C) Final 1-year radiograph of hip salvage intervention. This young man has returned to weight bearing without pain and his overall function has improved significantly. Note the appropriate station of the proximal femur without significant migration and pelvic support configuration.

Figure 10

Radiographs showing progressive hip displacement in a child with hypotonic CP (without adductor contractures) treated with guided growth of the proximal femur. Note the reduction in head-shaft angle (HSA, blue lines) and reduction in migration percentage (MP) post-operatively. Change in MP occurred rapidly, likely due to the relatively low pre-operative MP and high growth velocity of the proximal femur at this young age.