Achilles tendon ruptures most commonly occur in males between the ages of 30-50 years, as well as younger male and female athletes involved in jumping, running, cutting, and tumbling sports.(1,2) Achilles tears can be career ending and some don’t return to sport.(3) However, with proper care and the right treatment tools, many are able to return to a very physical active lifestyle.(3)
Plantar flexor strength deficits and altered gait biomechanics are common after Achilles tendon repair, but these challenges can be overcome through effective post-operative rehabilitation.(4) Due to tendon elongation following surgery, we know that increased muscle activation levels will be necessary to achieve desired results; so, we have to think about new standards for strength. It is critical to overcome any plantar flexor strength deficits (and then some) after surgery. This is where the use of biofeedback training and neuromuscular deficit testing can be essential to progress. mTrigger biofeedback can be used to optimize end range plantar flexion strength where the most apparent prolonged functional deficits occur. Furthermore, it provides a clear picture of the gastrocnemii neuromuscular deficit throughout the course of care.
Let’s take a look at a few examples
After surgery 61% of patients have difficulty performing this on flat ground and 89% are unable to perform a heel raise on a decline.(5) This points to a major area for improving rehab interventions: sEMG can help improve the performance of decline heel raises to increase strength & stamina in the plantar flexors (gastroc).
6 months following Achilles tendon repair with a 20% deficit in the plantar flexors shows there is still a long way to go in terms of strength building, as ideally, we want a better than 0% deficit, demonstrating greater strength / neuromuscular output on the involved side.
During more dynamic activities such as running, increased gastrocnemii activation levels are necessary to successfully perform forefoot running, which has been shown to have significantly decreased joint forces.(6) The gastrocnemii fibers are shortened during the majority of the forefoot striking running cycle- the same range where they are the weakest following repair.(6) Reduced PF endurance even several years after surgery can greatly affect someone’s ability to forefoot strike and potentially lead to preference of a rearfoot strike pattern.(3,6)
Notice the huge difference in ability accept weight, control deceleration, and absorb forces during the forefoot running compared to the heel strike pattern.
More on the impacts of Achille’s tendon repair
Despite studies showing increased levels of gastrocnemii muscle activation, a 10-30% functional calf strength and endurance deficit still exhists.(7) An increasing amount of plantarflexion deficit is seen at progressively increasing levels of plantarflexion: isometric strength deficits at 10° of PF were 17%, and 26% at 20°.(5) The most significant deficit in plantar flexion strength occurs at end range plantar flexion, as discussed above.(5)
Following surgical repair of the Achilles tendon, changes within the tendon structure and collagen composition (from a strong Type 1 to a less resistant Type 3)(7) leads to tendon elongation and subsequent deficits in strength, range of motion, power, gait, and running ability.(4,7) Some of these deficits can persist for years after surgical intervention. Deficits in heel raise performance for instance, which is a measure of strength and plantar flexion (PF) power, persisted for 10 years after surgery.(8) During gait, patients exhibited a slower gait speed, wider step width, and a shorter stride length compared to healthy controls.(4)
There is an ongoing debate regarding tendon elongation after surgery and its implications for post operative care.(9) As the greatest elongation occurs between 6-12 weeks post op, surgical protocols have a high variability in terms of bracing, weight bearing, and early mobilization.(1) The point of this post is not to debate protocols, but rather to discuss ways in which sEMG biofeedback can be used to help reverse the deficits that follow Achilles tendon repair surgery.
The elastic stretch and recoil of the Achilles tendon has been shown to contribute as much as 35% of the total energy storage during activities such as running.(6) However, in response to tendon lengthening, there is a deficit in tendon recoil on the injured side.(10) This must be compensated for by increased concentric muscular contraction.(10) Comparatively high activation of the plantar flexor muscles during the stance and push-off phases of gait indicate that the energy stored in the injured tendon during the eccentric phase is less effective; therefore, increased compensatory muscle activation is required to produce adequate propulsion force and perform the same motor tasks on the injured side compared to the non-injured side.(8,10)
After an Achilles tendon repair you must raise the bar for activation and strength of the plantarflexors in order to achieve optimal results. By using mTrigger biofeedback to supplement rehabilitation, you can maximize the output of the gastrocnemius during heel raise and functional tasks, as well as track functional deficit progress over time.
More on biofeedback for ankle injuries
Using biofeedback for return to sport
1. Eliasson P, Agergaard AS, Couppé C, et al. The Ruptured Achilles Tendon Elongates for 6 Months After Surgical Repair Regardless of Early or Late Weightbearing in Combination With Ankle Mobilization: A Randomized Clinical Trial. Am J Sports Med. 2018;46(10):2492-2502. doi:10.1177/0363546518781826
2. Ling D, Sleeper M, Casey E. Identification of Risk Factors for Injury in Women’s Collegiate Gymnastics With the Gymnastics Functional Measurement Tool. PM R. 2020;12(1):43-48. doi:10.1002/PMRJ.12184
3. Jandacka D, Silvernail JF, Uchytil J, Zahradnik D, Farana R, Hamill J. Do athletes alter their running mechanics after an Achilles tendon rupture? J Foot Ankle Res. 2017;10(1). doi:10.1186/S13047-017-0235-0
4. Nordenholm A, Senorski EH, Westin O, et al. Surgical treatment of chronic Achilles tendon rupture results in improved gait biomechanics. J Orthop Surg Res. 2022;17(1). doi:10.1186/S13018-022-02948-2
5. Orishimo KF, Schwartz-Balle S, Tyler TF, et al. Can Weakness in End-Range Plantar Flexion After Achilles Tendon Repair Be Prevented? Orthop J Sport Med. 2018;6(5). doi:10.1177/2325967118774031
6. Yong JR, Dembia CL, Silder A, Jackson RW, Fredericson M, Delp SL. Foot strike pattern during running alters muscle-tendon dynamics of the gastrocnemius and the soleus. Sci Rep. 2020;10(1). doi:10.1038/S41598-020-62464-3
7. Tarantino D, Palermi S, Sirico F, Corrado B. Achilles Tendon Rupture: Mechanisms of Injury, Principles of Rehabilitation and Return to Play. J Funct Morphol Kinesiol. 2020;5(4). doi:10.3390/JFMK5040095
8. Zellers JA, Marmon AR, Ebrahimi A, Grävare Silbernagel K. Lower extremity work along with triceps surae structure and activation is altered with jumping after Achilles tendon repair. J Orthop Res. 2019;37(4):933-941. doi:10.1002/JOR.24260
9. Zellers JA, Christensen M, Kjær IL, Rathleff MS, Silbernagel KG. Defining Components of Early Functional Rehabilitation for Acute Achilles Tendon Rupture: A Systematic Review. Orthop J Sport Med. 2019;7(11). doi:10.1177/2325967119884071
10. Wenning M, Mauch M, Heitner A, Lienhard J, Ritzmann R, Paul J. Neuromechanical activation of triceps surae muscle remains altered at 3.5 years following open surgical repair of acute Achilles tendon rupture. Knee Surg Sports Traumatol Arthrosc. 2021;29(8):2517-2527. doi:10.1007/S00167-021-06512-Z
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