The Ability of Ultrasonography, Magnetic Resonance Imaging and Bone Mineral Densitometry to Predict the Strength of Human Achilles' Tendons

Objective: To assess the value of ultrasonography (US), manetic resonance imaging (MRI), and bone mineral densitometry (BMD) in evaluating human Achilles' tendon strength. Design: Cross-sectional observational Study. Setting: Tertiary care hospital. Participants: Ninety-eight Achilles' tendons from 49 consecutive cadavers (26 men and 23 women with a mean age of 66.6 years) undergoing hospital autopsy were assessed. Interventions: Not applicable. Main Outcome Measures: Tendon dimensions on US and MRI, and T1-weighted optical density were measured. Areas of hypodensity, hyperdensity, calcification, and heterogeneity were identified on US. The BMD of each calcaneus was recorded. The tendons were mechanically tested to determine peak load at failure. Results: Sixteen patients (32.7%, 27 tendons) had abnormalities in 1 or both tendons on US and/or MRI (17 on US, 17 on MRI). Fifty-seven tendons (58%) ruptured in their midsubstance, at an average peak load of 4722 +/- 990N. Tendons with and without abnormalities on imaging had similar strengths (P>.05). Calcaneal BMD Correlated weakly with peak load at failure (r=.21, P<.05). Conclusions: The prevalence of Achilles' tendons abnormalities on US or MRI was 32.7% in our study group. Abnormalities on clinical imaging (US or MRI) were not predictive of the load at failure. Therefore, tendons with imaging abnormalities are not necessarily weaker, and one cannot predict the likelihood of rupture based on imaging results. Further, higher-powered studies could explore the ability of BMD to detect minimal clinically important differences and to predict Achilles' tendon weakness.