Flexor hallucis longus hypertrophy secondary to Achilles tendon tendinopathy: an MRI-based case-control study.

Wirth, Stephan H; Andronic, Octavian; Aregger, Fabian; Jungwirth-Weinberger, Anna; Jentzsch, Thorsten; Hecker, Andreas (2021). Flexor hallucis longus hypertrophy secondary to Achilles tendon tendinopathy: an MRI-based case-control study. European journal of orthopaedic surgery & traumatology, 31(7), pp. 1387-1393. Springer 10.1007/s00590-021-02891-8

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PURPOSE

The purpose of this study was to outline an indirect sign of advanced Achilles tendinopathy on magnetic resonance imaging (MRI), based on the hypothesis that these patients would present with secondary hypertrophy of the flexor hallucis longus muscle (FHL).

METHODS

MRI scans of Achilles tendon were analyzed retrospectively in two cohorts. The study group consisted of consecutive patients presenting with clinical signs of Achilles tendinopathy and no previous surgeries, while the control group were patients that had an MRI due to other reasons and no signs of tendinopathy. Two parameters from two muscle bellies were measured and compared on axial MRI scans 4-5 cm above the ankle joint line at the level of greatest thickness: area and diameter of the triceps surae (TS) and of the FHL muscle. Ratios (FHL/TS) were calculated for area (Ar) and diameter (Dm) measurements. Interobserver agreement was analyzed. A receiver operating characteristic (ROC) curve was created for both ratios to assess potential cutoff points to differentiate between the groups.

RESULTS

A total of 60 patients for each study group were included. Both ratios Ar(FHL/TS) and Dm(FHL/TS) showed significant higher values in the tendinopathy group (p < 0.001). There were strong to very strong intraclass correlation coefficients (ICC = 0.75-0.93). A diameter ratio Dm (FHL/TS) of 2.0 or higher had a sensitivity of 49% and specificity of 90% for concomitant Achilles tendinopathy.

CONCLUSION

In our patient cohort, FHL hypertrophy was observed in patients with Achilles tendinopathy as a possible compensatory mechanism. Measuring a diameter ratio Dm(FHL/TS) of 2.0 or higher on an axial MRI, may be indicative as an indirect sign of functional deterioration of the Achilles tendon.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Orthopaedic, Plastic and Hand Surgery (DOPH) > Clinic of Orthopaedic Surgery

UniBE Contributor:

Hecker, Andreas

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1633-8065

Publisher:

Springer

Language:

English

Submitter:

Kathrin Aeschlimann

Date Deposited:

25 Jan 2022 17:45

Last Modified:

05 Dec 2022 16:02

Publisher DOI:

10.1007/s00590-021-02891-8

PubMed ID:

33555443

Uncontrolled Keywords:

Achilles tendon MRI Achilles tendon tendinopathy Chronic achilles tendon rupture Flexor hallucis longus hypertrophy Flexor hallucis longus transfer

BORIS DOI:

10.48350/164040

URI:

https://boris.unibe.ch/id/eprint/164040

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