Does Patella Alta Influence Trochlear Morphology in Pediatric Patients with Cerebral Palsy? Associations with Age and
Giulia Beltrame1,2, Patrick P Nian1, Samuel A Beber1
1Lerner Children's Pavilion, Hospital for Special Surgery, New York City, NY, USA.
Insights
Patella alta in children with cerebral palsy (CP) is not linked to trochlear dysplasia. However, it may affect patellofemoral alignment with age, potentially causing pain or instability.
Area of Science:
- Orthopedics
- Pediatric Neurology
- Medical Imaging
Background:
- Patella alta is common in children with cerebral palsy (CP), often linked to quadriceps spasticity and tendon elongation.
- In typically developing children, patella alta is associated with trochlear dysplasia and instability.
- The relationship between patella alta, trochlear morphology, and functional ability in CP remains unclear.
Purpose of the Study:
- To determine if patella alta is associated with altered trochlear morphology in ambulatory children with CP.
- To evaluate the influence of age and functional severity on this association.
Main Methods:
- Retrospective study of pediatric patients (under 18) with hemiplegic or diplegic CP, Gross Motor Function Classification System levels I-III.
- Inclusion of patients with available knee radiographs and distal femur/proximal tibia CT scans.
- Analysis of 25 patients (48 limbs) for patellar height and trochlear morphology.
Main Results:
- Patella alta was identified in 35.4% of included limbs.
- No significant differences in trochlear morphology were found between CP groups or across functional levels.
- Older age correlated with physiologic trochlear development features; in patella alta cases, age correlated with increased tibial tubercle-to-trochlear groove (TT-TG) distance.
Conclusions:
- Patella alta is not associated with trochlear dysplasia in ambulatory children with CP.
- Persistent patella alta may influence patellofemoral alignment via age-related TT-TG increases, potentially leading to pain or instability.
- Further longitudinal studies and early clinical recognition are warranted.
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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