Ruptured human Achilles tendon has elevated metabolic activity up to 1 year after repair

Area of Science:

• Orthopedics and Sports Medicine
• Musculoskeletal Imaging and Metabolism

Background:

• Achilles tendon rupture healing is a slow process, with metabolic status often unknown at key rehabilitation milestones.
• Current rehabilitation protocols often permit running at 6 months post-injury, but the tendon's metabolic state remains unclear.

Purpose of the Study:

• To investigate tendon metabolism (glucose uptake) and vascularization at 3, 6, and 12 months after Achilles tendon rupture repair.
• To correlate metabolic and vascular findings with patient-reported outcomes.

Main Methods:

• Positron Emission Tomography (PET) with (18)F-FDG was used to measure glucose uptake in 23 patients post-Achilles tendon rupture repair.
• Power Doppler Ultrasonography (PDUS) assessed vascularization, and patient-reported outcomes were collected using the Achilles tendon rupture score (ATRS) and VISA-A questionnaire.
• Measurements were taken at 3, 6, and 12 months post-surgery.

Main Results:

• Repaired tendons exhibited significantly higher glucose uptake than intact tendons at all time points (3, 6, and 12 months).
• Vascularization (PDUS flow activity) was elevated at 3 and 6 months but normalized by 12 months.
• Higher glucose uptake at 6 months correlated negatively with patient-reported outcomes (ATRS), suggesting a link to poorer healing.

Conclusions:

• Tendon healing, indicated by metabolic activity and vascularization, continues for at least 6 months post-Achilles tendon rupture.
• Elevated metabolic activity persists beyond 1 year, even with normalized vascularization.
• High tendon metabolic activity at 6 months post-injury may be associated with suboptimal clinical healing outcomes.