Risk Factors Associated With Increased Anterior Pelvic Tilt in Ambulatory Children With Cerebral Palsy

Anterior pelvic tilt (APT) is common in children with Cerebral Palsy (CP) and may be associated with excessive lumbar lordosis, back pain, and associated functional limitations. Factors associated with increased APT are unclear but may be related to hamstring length, proximal muscle strength, sagittal plane gait deviations, or orthopedic surgery. The purpose of this study was to determine the risk factors associated with pathologic change in APT for ambulatory CP. In this IRB approved retrospective study, ambulatory children with bilateral spastic CP were identified from our institutional gait laboratory database from 2002-2022. Pairs of gait analyses were evaluated to determine change in APT with and without surgical interventions. A mixed effects linear regression analysis was conducted to predict which patient and surgical factors influenced change in APT between gait analyses. A logistic mixed effects generalized linear regression was also performed to identify factors associated with an APT increase of 5° or 10°. 528 children with CP were analyzed, 422 in the surgical group [GMFCS level I (n=35), II (n=281), III (n=106)] and 106 in the non-surgical group [GMFCS level I (n=17), II (n=64), III (n=25)]; with mean ages 11.1±3.8 and 10.0±3.6 years at first gait analysis, and 13.2±6.2 and 12.3±3.8 years at the follow-up gait analysis, respectively. Both the surgical and non-surgical groups exhibited APT at last follow-up, at 20±8.6 degrees and 20±8.5 degrees, respectively (p=0.63). Prior rhizotomy and hamstring lengthening (medial, medial+lateral) were significant factors for worsening APT, while Achilles lengthening, jump gait pattern, increased stance hip flexion, and increased initial APT, were protective (Table). The mean change in APT after medial and medial+lateral hamstring lengthening was 1±9° (p=0.046), and 4±9° (p < 0 .0001), respectively. The mean change in APT in children with history of rhizotomy was 2±11° (p=0.44). Rather than being solely related to hamstring lengthening, factors associated with changes in APT were multifactorial, with prior rhizotomy having the most profound effect. Contrary to conventional thinking, the presence of increased APT was not a risk factor for further progression. Factors possibly associated with ankle equinus – jump gait, Achilles lengthening – also had a protective effect. Identified risk factors for change in APT should be considered when developing treatment programs for children with bilateral CP, particularly for those with a normal or retroverted pelvis given their inherent susceptibility to worsening pelvic tilt. For any figures or tables, please contact the authors directly.