Factors Associated with Low Muscle Tone and Impact of Common Musculoskeletal Problems on Motor Development in Preterm Infants at One Year of Corrected Age

Introduction: Structural immaturity of muscular system in Preterm Infants (PTI) results in maturation related hypotonia which is found to be influenced by risk factors present at the time of birth. Low muscle tone can lead to lower extremity malalignment, abnormal positioning and loading resulting in musculoskeletal problems that could have an impact on motor development which is not well established. Aim: This study was carried out to analyse the risk factors associated with low muscle tone in PTI and the impact of common musculoskeletal problems on motor development of PTI at 1 year of corrected age. Materials and Methods: This Cross sectional study was carried out in 36 PTI and 36 Full Term Infants (FTI) who were recruited from Child Development unit and the details of risk factors were obtained from the records. Infants were assessed for muscle tone using Amiel Tison Angles (ATA) and Hyperextension of knee (HEK) was measured using goniometer. Foot prints were obtained and assessed for the level of Pes planus by Foot Arch Index (FAI) and Calcaneovalgus by Staheli index (SI). Peabody Developmental Motor Scale 2 (PDMS 2) was used to evaluate motor development. Backward multiple regression, Chi-square test Pearson's correlation were used for data analysis. Results: Backward multiple regression analysis showed statistically significant association of Birth weight, Gestational Age, and Apgar score with low muscle tone in PTI (p<0.05). Chi-square test was used to compare the muscle tone of PTI and FTI which showed that ATA of PTI was significantly higher than FTI but within physiological limits (p< 0.05). Pearson's correlation coefficient showed that there is statistically significant positive correlation between muscle tone and musculoskeletal problems and a negative correlation between musculoskeletal problems and Gross Motor Quotient (GMQ) of PDMS 2 in PTI at 1 year of corrected age (p< 0.05). Conclusion: Maturation related hypotonia carried during the first year of life brings about musculoskeletal problems which have an impact on motor development in PTI. The result accentuates that clinicians should address the subtle tonal deviations at an early age to prevent musculoskeletal problems and intervene if required when they are affecting the motor development of PTI.