Article
Transmission ultrasound: a novel technique to quantify post-surgical recovery of the achilles tendon after rupture
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Authors
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Mathias Wulf
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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Mihir Shanker
- Princess Alexandra Hospital, Brisbane, Australia
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Michael Lutz
- Mater Hospital, Brisbane , Australia
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Sue L. Hooper
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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Constantin E. Dlaska
- Univ.-Klinikum Charité, Campus Virchow-Klinikum Berlin, Centrum für Muskuloskeletale Chirurgie, Berlin, Germany
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Torsten Brauner
- FG Konservative und Rehabilitative Orthopädie, Technische Universität München, Munich, Germany
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Scott C. Wearing
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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Michael Schütz
- Univ.-Klinikum Charité, Campus Virchow-Klinikum Berlin, Centrum für Muskuloskeletale Chirurgie, Berlin, Germany
| Published: | October 23, 2017 |
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Outline
Text
Objectives: Achilles tendon rupture is a challenging condition. Re-rupture and long-term deficits, such as impaired muscle strength and tendon elongation, often occur.1 Little is known about the recovery of mechanical properties in the Achilles tendon post-repair. This prospective study used a novel, non-invasive transmission ultrasound (TU) technique to evaluate Achilles tendon properties during walking at 4, 10 and 24 months after surgical repair.
Methods: A custom-built TU device measured axial transmission speed of ultrasound (SOS) in repaired and contralateral tendons during walking in 5 patients (age, 53 ± 9 years; height, 177 ± 5 cm; weight, 83 ± 12 kg) with a mean postoperative period of 24 ± 3 months, and 2 patients (age, 45 ± 2 years; height, 178 ± 8 cm; weight, 91 ± 30 kg) at 4 and 10-months postoperatively. Patients completed 2 weeks of physiotherapy and reported mean Achilles Tendon Total Rupture Scores ranging from 14 (at 4 months) to 92 ± 5 (at 24 months).
The TU probe consisted of a 1MHz emitter and four regularly spaced receivers, maintained in contact with the skin by coupling medium and elastic band (Figure 1a [Fig. 1]). SOS was acquired at 120Hz during treadmill walking at fixed speed (1.1 m/s). A pressure platform measured ground reaction force (GRF). Paired t-tests were used to compare repaired and contralateral tendon (α =.05).
Results and Conclusion: SOS in repaired tendon was lower than in the contralateral limb, even at 24 months (P<.05). SOS was lowest at 4-months and highest at 24-months (Figure 1b [Fig. 1]). The range of SOS over the gait cycle was lowest at 4-months postoperatively (27 ± 2 m/s) and was only 9-17% of that at 10-months (155 ± 4 m/s) and 24-months (282 ± 19 m/s). SOS values for the contralateral tendon ranged from 1860-2180 m/s, which is similar to that of healthy adults.2 GRF peaks differed between limbs by 17% bodyweight at 4 months, 5% at 10 months and only 2% at 24 months.
A lower SOS in repaired tendon suggests a lower material stiffness than the contralateral tendon, even 24 months after surgery. The range of SOS over the gait cycle, which reflects calf muscle activity, was comparable between limbs at 24 months and was positively associated with postoperative duration and better clinical outcome. These findings highlight the potential of TU to non-invasively quantify the recovery of Achilles tendon properties and guide tendon rehabilitation programs after repair.
