Achilles Tendon Repair Cuts Ankle Range of Motion?

After Achilles tendon repair, reduced functional ankle range of motion can affect sports performance according to a new study.

“Deficits in sporting performance after Achilles tendon repair may be due to changes in musculotendinous unit structure, including elongation and muscle fascicle shortening,” the researchers of “Functional Ankle Range of Motion but Not Peak Achilles Tendon Force Diminished With Heel-Rise and Jumping Tasks After Achilles Tendon Repair” wrote.

The study, which was published on June 11, 2021, in The American Journal of Sports Medicine, examined whether Achilles tendon rupture affects triceps surae muscle force generation, functional ankle range of motion or both during sport activity.

The 11 athletes involved in the study were 1 to 3 years post open repair for an Achilles tendon rupture. Each were asked to complete a heel-rise task and 3 jumping tasks. Motion capture was used to analyze lower extremity biomechanics.

Overall, pelvic vertical displacement was reduced during the heel-rise (mean difference -12.8%; p = .026), but not during the jumping task (p > .1). In the concentric phase of all tasks, peak ankle plantarflexion angle (range of mean difference, -19.2% to -48.8%; p < .05) and total plantar flexor work (range of mean difference, -9.5% to -25.7%; p < .05) were also lower on the repaired side compared to the uninjured side.

No significant differences were found, however, in peak Achilles tendon load or impulse with any of the tasks, including during eccentric phases.

“Impaired task performance or increased demands on proximal joints were observed on the repaired side in tasks isolating ankle function. Tasks that did not isolate ankle function appeared to be well recovered, although functional ankle range of motion was reduced with rupture,” the researchers wrote.

“Reduced plantar flexor muscle-tendon unit work supports previous reports that an elongated tendon and shorter muscle fascicles caused by Achilles tendon rupture constrain functional capacity. Achilles tendon peak load and impulse were not decreased, suggesting that reduced and shifted functional ankle range of motion (favoring dorsiflexion) underlies performance deficits.”

They added, “These findings point to the need to reduce tendon elongation and restore muscle length of the triceps surae after Achilles tendon rupture in order to address musculature that is short, but not necessarily weak for improved performance with sports-related activities.”