Pathomechanics of lumbrical and flexor digitorum profundus muscle tears in climbers: A cadaveric model.
Level 5 - mechanism / opinion, no new human data
Cadaveric biomechanical investigation
PubMed 38924964 · doi:10.1016/j.jbiomech.2024.112196
What was done
Ten fresh-frozen non-paired cadaveric forearms and hands were tested on a custom loading apparatus to model the quadriga effect in sport climbing. The flexor digitorum profundus tendon of the fifth finger was loaded to induce isolated flexion until tissue rupture. Proximal tendon gliding distance, fifth metacarpophalangeal joint flexion, and load at failure were measured.
What was found
Rupture occurred across all ten specimens at a mean load of 11 kg (SD 4.94), with 9.23 mm (SD 3.55) of proximal tendon gliding and 21.4 degrees (SD 28.91) of metacarpophalangeal joint flexion. In all specimens, the fourth lumbrical detached from the fourth flexor digitorum profundus from distal to proximal, and structural changes in the flexor digitorum profundus tendons occurred at the distal forearm level.
Why it matters
This provides experimental biomechanical thresholds for lumbrical tears and deep flexor damage during asymmetric finger loading seen in climbing.
Limits
The study is restricted to a small sample of ten cadaveric specimens with high variance in joint flexion angles. It is an in vitro biomechanical model that cannot replicate active neuromuscular coordination, living tissue repair, or the complex dynamic forces of climbing.