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

TY - JOUR

T1 - Ruptured human Achilles tendon has elevated metabolic activity up to 1 year after repair

AU - Eliasson, Pernilla

AU - Couppé, Christian

AU - Lonsdale, Markus

AU - Svensson, René B

AU - Neergaard, Christian

AU - Kjær, Michael

AU - Friberg, Lars

AU - Magnusson, S Peter

PY - 2016/9/1

Y1 - 2016/9/1

N2 - Purpose: Following Achilles tendon rupture, running is often allowed after 6 months. However, tendon healing is slow and the metabolic status of the tendon at this point is unknown. The purpose of this study was to investigate tendon metabolism (glucose uptake) and vascularization at 3, 6 and 12 months after Achilles tendon rupture as measured using PET and power Doppler ultrasonography (PDUS). Methods: The study group comprised 23 patients with surgically repaired Achilles tendon rupture who were investigated at 3 months (n = 7), 6 months (n = 7) and 12 months (n = 9) after surgery. The triceps surae complex was loaded over 20 min of slow treadmill walking while a radioactive tracer (18F-FDG) was administered prior to PET. Vascularization was measured in terms of PDUS flow activity, and patient-reported outcomes were scored using the Achilles tendon rupture score (ATRS) and sports assessment (VISA-A) questionnaire. Results: Relative glucose uptake (18F-FDG) was higher in repaired tendons than in intact tendons at all time-points (6, 3 and 1.6 times higher at 3, 6 and 12 months, respectively; P ≤ 0.001), and was also higher in the tendon core than in the periphery at 3 and 6 months (P ≤ 0.02), but lower at 12 months (P = 0.06). Relative glucose uptake was negatively related to ATRS at 6 months after repair (r = −0.89, P ≤ 0.01). PDUS flow activity was higher in repaired tendons than in intact tendons at 3 and 6 months (P < 0.05 for both), but had normalized by 12 months. Conclusion: These data demonstrate that the healing process as determined by metabolic activity and vascularization continues for 6 months after injury when large loads are typically allowed on the tendon. Indeed, metabolic activity remained elevated for more than 1 year after injury despite normalized vascularization. The robust negative correlation between tendon metabolism and patient-reported outcome suggests that a high metabolic activity 6 months after the injury may be related to a poor clinical healing outcome.

AB - Purpose: Following Achilles tendon rupture, running is often allowed after 6 months. However, tendon healing is slow and the metabolic status of the tendon at this point is unknown. The purpose of this study was to investigate tendon metabolism (glucose uptake) and vascularization at 3, 6 and 12 months after Achilles tendon rupture as measured using PET and power Doppler ultrasonography (PDUS). Methods: The study group comprised 23 patients with surgically repaired Achilles tendon rupture who were investigated at 3 months (n = 7), 6 months (n = 7) and 12 months (n = 9) after surgery. The triceps surae complex was loaded over 20 min of slow treadmill walking while a radioactive tracer (18F-FDG) was administered prior to PET. Vascularization was measured in terms of PDUS flow activity, and patient-reported outcomes were scored using the Achilles tendon rupture score (ATRS) and sports assessment (VISA-A) questionnaire. Results: Relative glucose uptake (18F-FDG) was higher in repaired tendons than in intact tendons at all time-points (6, 3 and 1.6 times higher at 3, 6 and 12 months, respectively; P ≤ 0.001), and was also higher in the tendon core than in the periphery at 3 and 6 months (P ≤ 0.02), but lower at 12 months (P = 0.06). Relative glucose uptake was negatively related to ATRS at 6 months after repair (r = −0.89, P ≤ 0.01). PDUS flow activity was higher in repaired tendons than in intact tendons at 3 and 6 months (P < 0.05 for both), but had normalized by 12 months. Conclusion: These data demonstrate that the healing process as determined by metabolic activity and vascularization continues for 6 months after injury when large loads are typically allowed on the tendon. Indeed, metabolic activity remained elevated for more than 1 year after injury despite normalized vascularization. The robust negative correlation between tendon metabolism and patient-reported outcome suggests that a high metabolic activity 6 months after the injury may be related to a poor clinical healing outcome.

KW - Achilles Tendon

KW - Adult

KW - Female

KW - Fluorodeoxyglucose F18

KW - Humans

KW - Longitudinal Studies

KW - Male

KW - Positron-Emission Tomography

KW - Radiopharmaceuticals

KW - Recovery of Function

KW - Reproducibility of Results

KW - Rupture

KW - Sensitivity and Specificity

KW - Tenotomy

KW - Tissue Distribution

KW - Treatment Outcome

KW - Controlled Clinical Trial

KW - Journal Article

U2 - 10.1007/s00259-016-3379-4

DO - 10.1007/s00259-016-3379-4

M3 - Journal article

C2 - 27072812

SN - 1619-7070

VL - 43

SP - 1868

EP - 1877

JO - European Journal of Nuclear Medicine and Molecular Imaging

JF - European Journal of Nuclear Medicine and Molecular Imaging

IS - 10

ER -