Regional strain variations in the human patellar tendon

Area of Science:

• Biomechanics
• Musculoskeletal Research
• Sports Medicine

Background:

• Understanding localized tendon strain is crucial for diagnosing and treating injuries.
• The patellar tendon's complex structure suggests varied mechanical responses.
• Previous research has not fully characterized in vivo regional strain differences.

Purpose of the Study:

• To investigate localized patellar tendon strain in vivo.
• To compare strain across deep, middle, and surface structures.
• To examine strain at proximal and distal tendon aspects during isometric contractions.

Main Methods:

• Real-time B-mode ultrasonography and dynamometry were used in male subjects.
• Ramped isometric voluntary contractions were performed.
• Automated pixel tracking analyzed regional tendon excursion and calculated strain.

Main Results:

• Patellar tendon strain increased with force for all regions.
• The anterior proximal region exhibited significantly greater strain (7.5%) than posterior (3.7%) and mid (5.5%) layers.
• The distal posterior region showed greater strain (7.9%) than mid (5.0%) and anterior (5.4%) regions.

Conclusions:

• Significant regional differences in patellar tendon strain exist during isometric contractions.
• Lower posterior proximal strain may contribute to stress shielding.
• These findings offer insights into the etiology of insertional tendinopathy.