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Strain patterns in the patellar tendon and the implications for patellar tendinopathy
Louis C Almekinders1, Jurrien H Vellema, Paul S Weinhold
1Department of Orthopaedic Surgery, Sports Medicine Section, University of North Carolina, Chapel Hill, NC 27599-7055, USA.
Summary
Investigating human patellar tendon strain revealed that the posterior side, often affected by patellar tendinopathy, experiences decreased tensile load during knee flexion. This suggests stress shielding, not repetitive tensile forces, may be key in insertional tendinopathy.
Area of Science:
- Orthopedics
- Biomechanics
- Sports Medicine
Background:
- Patellar tendinopathy, or Jumper's Knee, affects the patellar tendon, often impacting the posterior proximal region.
- Understanding the strain distribution within the patellar tendon is crucial for elucidating the etiology of tendinopathy.
Purpose of the Study:
- To investigate the strain patterns in the human patellar tendon, specifically in the proximal posterior region.
- To determine if this commonly affected area experiences the highest tensile loads during knee flexion.
Main Methods:
- Eight fresh frozen human knees were used.
- Strain gauges were attached to the anterior and posterior sides of the proximal patellar tendon.
- Static and dynamic measurements were taken during knee flexion from 0 to 60 degrees.
Main Results:
- Uniform tensile strain was observed in full knee extension.
- During flexion, anterior strain increased while posterior strain decreased in the central proximal tendon.
- The posterior proximal patellar tendon, commonly affected by tendinopathy, did not exhibit the highest tensile loads.
Conclusions:
- The posterior proximal patellar tendon may not be subjected to the highest tensile loads during functional knee flexion.
- Stress shielding could be a more significant etiological factor in insertional patellar tendinopathy than repetitive tensile loads.