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Patellar Tendon Stiffness Is Not Reduced During Pregnancy
Marie Elena Bey1,2, Robert Marzilger1,2, Larry Hinkson3
1Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
Frontiers in Physiology
|April 16, 2019
Summary
Pregnancy does not appear to alter patellar tendon stiffness, contrary to common belief. However, tendon length increases during and after pregnancy, potentially impacting injury risk in athletes.
Area of Science:
- Sports Medicine
- Physiology
- Biomechanics
Background:
- Hormonal changes in pregnancy are thought to increase connective tissue compliance, raising injury risk.
- Pelvic ligament laxity increases for childbirth, but tendon mechanical properties during pregnancy are understudied.
Purpose of the Study:
- To investigate the mechanical properties of the patellar tendon across different stages of pregnancy and postpartum.
- To examine changes in tendon stiffness, strength, and length during and after pregnancy.
Main Methods:
- Longitudinal study involving 19 pregnant women and 11 non-pregnant controls.
- Measurements included muscle strength and patellar tendon mechanical properties using ultrasound, kinematics, and electromyography.
- Data collected in early pregnancy (EP), late pregnancy (LP), and postpartum (PP).
Main Results:
- Patellar tendon stiffness, strength, and relative strain remained unchanged during pregnancy and postpartum compared to controls.
- Tendon length at 90° knee flexion significantly increased during and after pregnancy (PP > EP; PP > controls).
Conclusions:
- Patellar tendon stiffness is not universally affected by pregnancy, challenging assumptions of increased tendon compliance.
- The progressive increase in tendon rest length during and after pregnancy warrants further investigation regarding injury risk.
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