Non-operative method in management of chronic pain in Achilles tendonitis:
The Achilles tendon is the strongest tendon in the human body. This tendon connects the plantaris, gastrocnemius, and soleus to the calcaneus bone. When we contract the muscle, all the force goes through the tendon, at the point where it connects to the bone. So, the tendon must be strong, and it is elastic because it can store energy for running or jumping. The tendon is made of different bundles and contains type-1 collagen fibers. Tendons can withstand a lot of repetitive loads, but if the tendon is strained for a long time or with load beyond its capacity, then it can get microtears. The degeneration of collagen fiber in response to chronic overuse is called tendinosis. The body can heal the micro tears but if it is repeatedly strained so that the rate of degradation exceeds that of regeneration then, the injury leads to inflammation, then this condition is called tendonitis. Achilles tendonitis is characterized by stiffness in Achilles tendon proximal to calcaneus bone, that is aggravated when walking after prolonged rest due to contraction and tightening of the tendon, and physical activity can strain the tendon and damage it.
The structure and composition of tendons allow for their unique mechanical behavior. Just like concrete, the tendon can handle more stress than strain. Tendons also have viscoelastic properties, and their mechanical behavior is dependent on the rate of mechanical strain. So, the tendon is more deformable at low strain and allows it to absorb more mechanical energy. However, at high strain, it becomes stiff and less deformable, which helps in transmitting large muscular loads to the bone. But when the load exceeds its capacity, the tendon cannot transfer the energy by elongating furthermore, which leads to microtear and, has a chance to rupture the tendon. On the other hand, because of the viscoelastic nature of the tendon, the damage is further added when unloading, because the tendon tends to stay elongated more compared to the elongation it had from load of the same weight, which increase the time under strain of the tendon, resulting in additional injury, even when the load is removed (Thomas, 2018).
In the case of insertional Achilles tendonitis, there is also damage due to shearing forces. Shearing forces differ from high tensile loads mentioned above because there is not that large storage and release of energy but rather repetitive motion like kicking in swimming, where there is both dorsiflexion and plantarflexion of the foot. When there is continuous friction between the bone and tendon, it can cause inflammation of the bursa, which was supposed to act as a cushion between the tendon and the bone. This can also lead to bursitis, which is inflammation of the bursa.
1. Eccentric loading compared with shock wave treatment for chronic insertional Achilles tendinopathy.
2. Novel Physical Therapy Protocol Results in Increased Compressive Strain and Improved Outcomes in Insertional Achilles Tendinopathy
3. Eccentric Exercise Versus Eccentric Exercise and Soft Tissue Treatment (Astym) in the Management of Insertional Achilles Tendinopathy: A Randomized Controlled Trial
In this paper, I will compare the above non-operative methods for the treatment of Achilles tendonitis. Rompe et al. (2008) conducted a study to compare the treatment method of eccentric loading with shock wave treatment for chronic insertional Achilles tendinopathy. In his study, there were 50 participants, and they were randomly assigned into two groups; eccentric load and shock wave treatment. Each group had 25 subjects randomly assigned by a computer. They then did a follow up after 4 months and, found that the mean pain rating for eccentric loading and shock wave treatment had decreased by 7-5 points and 7-3 points respectively. The Victorian Institute of Sport Assessment – Achilles (VISA-A) questionnaire was used to assess pain and found eccentric loading and shock wave treatment group to score from 53-63 and 53-80 respectively. In the experiment, patients were asked to carry out the exercise through mild or moderate pain and stopping only if it is unbearable. The subjects could cross over after four months interval, in both groups. Their findings supported that the shock wave treatment is more favorable even after the crossover.
The subjects were refrained from using innersoles and advised not to follow other physical therapy. If necessary, naproxen (1000mg daily) or paracetamol (2000 to 4000mg daily) were prescribed. The result of the experiment could have been influenced by the permit of using paracetamol and naproxen when the subject complained of pain. Also, the experiment seems aggressive in increasing the eccentric load by 5 kg if the subjects were able to complete 3 sets easily. The tendon is already injured, keeping that fact in mind the researcher should have gradually increased the weight, and should not have allowed an abrupt increase in weight by 5 kg. This could have been the reason for 2 people leaving from group 1 due to persistent pain. So, the result of this experiment is not reliable.
Kelly et al. (2017) did an experiment to combine isometric and eccentric exercises to increase transverse compressive strain and decrease tensile strain (force parallel to tendon fibers) in insertional Achilles tendonitis (IAT). They had 42 patients, with 56 % women (58.9 + 8.6 years) and men (56.7 + 9.9 years). An ultrasound was done to determine transverse compressive strain and axial tensile strain during the dorsiflexion task. For the treatment, the subjects were asked to add progressive loading of the Achilles tendon while avoiding ankle dorsiflexion. Twenty-three of 27 subjects, had clinically significant improvements in their VISA-A scores.
After completing the physical therapy program, there was an increase in transverse compressive strain in the superficial Achilles tendon compared to the pre-therapy value when standing (mean change 52%, p=0.043). In addition, there was a decrease in axial tensile strain within the deep portion of the tendon in response to physical therapy (mean change 53% p=0.0434).
Treating IAT patients with combined therapy of eccentric exercises and isometric exercises show improved outcomes. Compared to the first experiment by Rompe et al. (2008), this experiment seems more reliable.
In McCormack et al. (2016) experiment, they compared eccentric exercises with self-tissue treatment and eccentric exercises. The had 16 subjects randomly assigned into these two groups; eccentric exercise and self-tissue treatment and eccentric exercise. The assessed the pain using VISA-A scores 4,8,12,26, and 52 weeks. They found that the first group was able to maintain significant improvement over the short and long term, and more number of people were found to have significant improvement in group 1. The second group also showed significant improvement in VISA-A scores. However, there was no significant difference in VISA-A between these groups.
References:
Tendon Biomechanics. (2018, August 30). Physiopedia, . Retrieved 01:17, October 3, 2019 from https://www.physio-pedia.com/index.php?title=Tendon_Biomechanics&oldid=197336.
Tendon Load and Capacity. (2019, September 20). Physiopedia, . Retrieved 01:41, October 3, 2019 from https://www.physio-pedia.com/index.php?title=Tendon_Load_and_Capacity&oldid=223307.
Rompe, Jan & Furia, John & Maffulli, Nicola. (2008). Eccentric loading compared with shock wave treatment for chronic insertional Achilles tendinopathy. A randomized, controlled trial. The Journal of bone and joint surgery. American volume. 90. 52-61. 10.2106/JBJS.F.01494.
Kelly, M., Bucklin, M., Chimenti, R., Olson, R., Richards, M., Buckley, M., … Flemister, A. (2017). Novel Physical Therapy Protocol Results in Increased Compressive Strain and Improved Outcomes in Insertional Achilles Tendinopathy. Foot & Ankle Orthopaedics. https://doi.org/10.1177/2473011417S000238
McCormack, J. R., Underwood, F. B., Slaven, E. J., & Cappaert, T. A. (2016). Eccentric Exercise Versus Eccentric Exercise and Soft Tissue Treatment (Astym) in the Management of Insertional Achilles Tendinopathy: A Randomized Controlled Trial. Sports Health. SAGE JOURNALS, 8(3), 230–237. https://doi.org/10.1177/1941738116631498
Tenjing Sherpa 