Characterization of patellar tendon stiffness in children with cerebral palsy with strain elastography

Cerebral palsy (CP) is a neurodevelopmental disorder that affects neuromuscular control and alters the mechanical structure of the musculoskeletal system, often leading to symptoms such as impaired posture and crouch gait, which are often treated with physical therapy. While physical therapy aims to help improve strength and functional mobility, treatment is largely based on qualitative clinical assessments. This study aims to characterize differences in patellar tendon stiffness between children with CP and their typically developing (TD) peers using ultrasound strain elastography to support quantitative and personalized physical therapy treatment. The right patellar tendon of twenty children (12 TD and 8 CP) aged 10 through 16 was imaged in the sagittal plane at the midsection of the tendon during manual compression to capture pre- and post-compression radio frequency data which were processed using the GLobal Ultrasound Elastography (GLUE) algorithm to produce strain elastograms. Regions within the patellar tendon and surrounding tissue were analyzed to extract quantitative metrics including contrast, strain ratio, and strain difference, which were statistically compared between children with CP and their TD peers as well as across age- and sex-matched groups. Children with CP tended to have higher metric values compared to their TD peers indicating relatively softer tendons compared to the surrounding tissue. For example, the median and inter quartile range (IQR) contrast values for children with CP and their TD peers was 0.508 (IQR: 3.18) and -0.518 (IQR: 3.28), respectively. These findings are promising as a baseline for further investigations into noninvasive, quantitative methods for assessing patellar tendon stiffness to guide personalized physical therapy for children with CP.