Triceps surae morphology and ankle functionality 2 years after Achilles tendon rupture repair: traditional versus...

Achilles tendon rupture impairs the functional performance of the triceps surae muscle-tendon unit. However, long-term effects of different rehabilitation programs on these impairments remain unclear. This study evaluated the long-term effects of early rehabilitation versus cast immobilization after Achilles tendon repair. We also examined whether the uninjured side could serve as a reference for the "healthy" side. Males with previous Achilles tendon rupture (n = 20) and a group of healthy male controls (CTR; n = 10) participated. Participants with Achilles tendon rupture included a short-term physical therapy group (STPT; n = 10) and a plaster cast group (PC; n = 10). Triceps surae morphology and ankle functionality were compared among groups. No between-group differences were found in the patient-reported outcomes. The injured side presented lower heel rise height, plantar flexors strength, gastrocnemius medialis thickness, calf volume, and shorter fascicle length than CTR. On the injured side, the STPT preserved ankle range of motion and showed greater plantar flexion and total range of motion than the PC. We used a computational model that demonstrated that tendon elongation was the main determinant of heel rise height deficit. The uninjured side presented lower heel rise height than the CTR group. Despite favorable patient-reported outcomes, long-term structural and functional deficits persist after Achilles tendon rupture, regardless of rehabilitation approach. Findings suggest that the rehabilitation programs used did not fully restore muscle-tendon function and highlight limitations of using the uninjured side as a control.NEW & NOTEWORTHY This study compares early mobilization and plaster cast rehabilitation after Achilles tendon rupture, with surgeries performed by a single surgeon. We demonstrate that long-term structural and functional deficits persist 2 yr after Achilles tendon rupture, regardless of rehabilitation type. With a computational model, we investigated the mechanisms underlying heel-rise deficits, quantifying structural contributions. Including a healthy control group revealed that the uninjured side also shows impairments, calling into question its use as a reference in clinical and research settings.