In vitro fatigue of human flexor digitorum tendons

Area of Science:

• Biomechanics
• Musculoskeletal Disorders
• Occupational Health

Background:

• Carpal tunnel syndrome and trigger finger are common work-related musculoskeletal disorders (WMSDs).
• Current WMSD evaluation tools rely on lower-limb tendon fatigue data, potentially causing inaccuracies for wrist injuries.
• Overuse injuries like these are linked to repetitive loading and can be analyzed using fatigue failure principles.

Purpose of the Study:

• To characterize the fatigue behavior of flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons.
• To investigate the unique stress-fatigue life relationship of FDP and FDS tendons.
• To identify potential new metrics for evaluating WMSD risk.

Main Methods:

• Cyclical loading was applied to FDP and FDS tendons to assess fatigue behavior.
• The relationship between applied stress and fatigue life was analyzed.
• Correlations between creep, damage rate, and fatigue life were examined.

Main Results:

• FDP and FDS tendons exhibited a logarithmic relationship between stress and fatigue life, similar to other tendons.
• The specific parameters of this relationship for FDP/FDS tendons were unique.
• Creep and damage rate showed the strongest correlation with fatigue life.

Conclusions:

• The unique fatigue behavior of FDP and FDS tendons may enhance the accuracy of current WMSD evaluation tools for carpal tunnel syndrome and trigger finger.
• Creep and damage rate are promising metrics for future WMSD risk evaluation.
• This research provides crucial data for understanding and preventing hand-related overuse injuries.