Exploration of muscle–tendon biomechanics one year after Achilles tendon rupture and the compensatory role of flexor hallucis longus

Khair, Ra'ad M., Stenroth, Lauri, Cronin, Neil ORCID: 0000-0002-5332-1188, Ponkilainen, Ville, Reito, Aleksi and Finni, Taija (2023) Exploration of muscle–tendon biomechanics one year after Achilles tendon rupture and the compensatory role of flexor hallucis longus. Journal of Biomechanics, 152. Art 111586. doi:10.1016/j.jbiomech.2023.111586

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Achilles tendon (AT) rupture leads to long-term structural and functional impairments. Currently, the predictors of good recovery after rupture are poorly known. Thus, we aimed to explore the interconnections between structural, mechanical, and neuromuscular parameters and their associations with factors that could explain good recovery in patients with non-surgically treated AT rupture. A total of 35 patients with unilateral rupture (6 females) participated in this study. Muscle-tendon structural, mechanical, and neuromuscular parameters were measured 1-year after rupture. Interconnections between the inter-limb differences (Δ) were explored using partial correlations, followed by multivariable linear regression to find associations between the measured factors and the following markers that indicate good recovery: 1) tendon length, 2) tendon non-uniform displacement, and 3) flexor hallucis longus (FHL) normalized EMG amplitude difference between limbs. Δmedial gastrocnemius (MG) (β = −0.12, p = 0.007) and Δlateral gastrocnemius (β = −0.086, p = 0.030) subtendon lengths were associated with MG tendon Δstiffness. MG (β = 11.56, p = 0.003) and soleus (β = 2.18, p = 0.040) Δsubtendon lengths explained 48 % of variance in FHL EMG amplitude. Regression models for tendon length and non-uniform displacement were not significant. Smaller inter-limb differences in Achilles subtendon lengths were associated with smaller differences in the AT stiffness between limbs, and a smaller contribution of FHL muscle to the plantarflexion torque. In the injured limb, the increased contribution of FHL appears to partially counteract a smaller contribution from MG due to the elongated tendon, however the role of FHL should not be emphasized during rehabilitation to allow recovery of the TS muscles.

Item Type: Article
Article Type: Article
Uncontrolled Keywords: Ultrasonography; Flexor hallucis longus muscle; Tendons; Function; Mechanical; Muscle
Subjects: G Geography. Anthropology. Recreation > GV Recreation Leisure > GV557 Sports
Q Science > QP Physiology > QP301.H75 Physiology. Sport
R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Schools and Research Institutes > School of Business, Computing and Social Sciences
Research Priority Areas: Health, Life Sciences, Sport and Wellbeing
Depositing User: Anne Pengelly
Date Deposited: 25 Apr 2023 09:38
Last Modified: 31 Aug 2023 08:24
URI: https://eprints.glos.ac.uk/id/eprint/12657

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