Abstract
Background:
Patella alta is common in children with cerebral palsy (CP), often resulting from quadriceps spasticity and tendon elongation. In typically developing children, patella alta is linked to trochlear dysplasia and instability. Whether these associations exist in CP, and how they vary with age and functional ability, has not been established.
Purpose:
We sought to determine whether patella alta is associated with alterations in trochlear morphology in ambulatory children with CP and to evaluate the influence of age and functional severity.
Methods:
We conducted a retrospective study of pediatric patients under the age of 18 diagnosed with hemiplegic or diplegic CP. We included patients classified as Gross Motor Function Classification System levels I to III to ensure relative ambulatory function and minimize confounding due to severe joint contractures. Inclusion criteria included patients who had had a lateral radiograph of the knee and axial computed tomography scans of the distal femur and proximal tibia showing the anterior tibial tuberosity. Eligible patients were identified through a comprehensive search of the institutional electronic medical record system between 2016 and 2024.
Results:
Of the 164 patients identified, 31 were included based on available imaging suitable for the assessment of both patellar height and trochlear morphology; 6 of these patients were excluded due to poor image quality, resulting in a final cohort of 25 patients and 48 limbs. Patella alta was identified in 17 knees (35.4%). No differences in trochlear morphology were observed between groups or across functional levels. In both groups, older age correlated with features of physiologic trochlear development, including increased trochlear groove depth and narrower sulcus angle. in patients with patella alta, age also correlated with greater tibial tubercle to trochlear groove (TT-TG) distance.
Conclusion:
Patella alta was not associated with trochlear dysplasia in ambulatory children with CP. However, its persistent presence may alter patellofemoral alignment through age-related increases in TT-TG distance, contributing to pain or instability, highlighting the need for longitudinal studies and early recognition in clinical care.
Level of Evidence:
Level IV, Retrospective Prognostic Study
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