Introduction of a New Index as an Indicator for Achilles Tendon Tendinopathy

Abstract

Category: Sports Introduction/Purpose: Achilles tendon tendinopathy is a common problem in our daily practice. The initial therapy consists of conservative treatment and usually leads to a reduction of pain. In some cases though, there is need for surgical treatment. The most common procedure is debridement of the tendon. If there is advanced damage of the tendon, a flexor hallucis longus (FHL) transfer may be indicated. In the current literature, there is a lack of hard criteria about the indications for such a transfer. Methods: We searched our radiologic database from the years 2016 and 2017 for magnetic resonance imaging (MRI) scans of the Achilles tendon. 60 patients were included in a tendinopathy group and 60 patients in a control group with no signs of tendinopathy. Inclusion criteria were severe tendinopathy for the tendinopathy group and a normal Achilles tendon for the control group. Exclusion criteria were other relevant morphologic changes or history of relevant surgery of the lower limb. Axial MRI scans were analyzed on a level of 4-5 centimeters above the ankle joint. The area of triceps surae (TS) and FHL were measured as well as the diameter of TS and an oblique diameter of FHL (from the medial corner of the fibula to the posteromedial corner of the FHL muscle). Then, quotients of the area of the FHL/TS and diameter of the FHL/TS were built and interobserver agreement was analyzed. Results: The quotients for area and for diameter of the FHL/TS showed significantly (p<0.001) higher values in the tendinopathy group. We also found strong to very strong interobserver agreements (rho=0.744). The median value for the quotient of diameter FHL/TS was 2.0 (interquartile range [IQR] 0.8) in the tendinopathy group versus (vs) 1.7 (IQR 0.3) in the control group. The median value for the quotient of area FHL/TS was 1.8 (IQR 1.3) in the tendinopathy group vs 1.3 (IQR 0.7) in the control group. Conclusion: The quotient of the diameter FHL/TS is easy to obtain in our clinical practice. It indicates a relevant FHL hypertrophy, which occurs in advanced Achilles tendon tendinopathy. A value of 2.0 and higher is indicative of symptomatic tendinopathy and may ultimately support the indication for a FHL transfer, which should be the topic of future research.