Introduction Achilles tendon is the most common tendon to suffer for complete rupture. Physically active young adults are often treated with surgery. Most of the patients do not suffer from activity limitations after injury3 but performance level is often significantly decreased.1,2
The purpose of this study was to follow recovery of Achilles tendon and triceps surae muscles after complete Achilles tendon rupture and subsequent surgery. This study served as a pilot phase for future research project.
Methods Three subjects were recruited to this pilot phase of the study. Subjects were first time measured 2 to 8 months after injury and followed 6 to 8 months. Plantarflexion strength was measured with isometric maximal voluntary contraction in a dynamometer, triceps surae muscle size and architecture was measured using ultrasonography and Achilles tendon stiffness was calculated from force-elongation relationship (Figure 1) measured using dynamometer and ultrasonography.
Results One of the three subjects reached plantarflexion strength level comparable to healthy leg. Other two subjects improved strength during follow-up but reached only 72 and 77% of the healthy leg’s value at the end of the follow-up.
Similarly to plantarflexion strength, gastrocnemius cross-sectional area recovered only in one of the three subjects during the follow-up. In the two subjects suffering from strength deficit after follow-up, pennation angle of medial gastrocnemius was larger in the injured leg during force production.
Achilles tendon stiffness was not greatly different between the legs at the end of the follow-up and increased in each subject during the follow-up (Figure 2).
Discussion Persistent atrophy of the calf muscles may explain why two of the subjects were not able to produce similar plantarflexion force with the injured leg 10 to 16 months after injury compared to the healthy leg. Other factors contributing to force deficit may be related to possible elongation of the injured Achilles tendon causing alterations to muscle mechanics. For example, larger pennation angle will decrease the proportion of muscle force transmitted to skeleton.
In future, the aim is to start systematic collection of data from patients recovering from Achilles tendon rupture in order to understand why some develop persistent physical deficits and to gain knowledge that can be used to develop operation and rehabilitation regimes.
References 1 Amin, et al. Am J Sports Med. 2013;41:1864–1868
2 Olsson, et al. Knee Surg Sports Traumatol Arthrosc. 2011;19:1385–1393
3 Strauss, et al . Injury Int J Care Injured. 2007;38:832–838
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