By John K. Hyland, DC, MPH, DACBR, DABCO, CSCS

Achilles tendon problems are common injuries in athletes, and they are also found frequently among aging and active individuals. Those who run and/or climb stairs are particularly at risk of injury, but problems are also frequent in anyone who participates in activities such as racquet sports, volleyball, and soccer. ¹ Injuries are usually secondary to biomechanical deficits, ² and most will eventually respond well to conservative care, including exercise and Chiropractic adjustment procedures. Pain and dysfunction of the Achilles tendon can be a disabling factor that inhibits the effort to persist in regular fitness exercise for wellness.

Functional Anatomy

The Achilles is the combined tendon of the gastrocnemius and soleus muscles. It is surrounded by a paratenon (rather than a synovial sheath), which is continuous with the fascia of the gastrocnemius and soleus muscles and the periosteum of the calcaneus. Tendinopathy usually occurs within that part of the tendon that is 2 to 6 cm proximal to the calcaneal insertion at a site of decreased vascularization. ³

Poor blood flow may be a contributing factor to Achilles tendon overuse injuries, and especially for tendon tears. Clement and his fellow authors speculate that “in individuals who overpronate, the conflicting internal and external rotatory forces imparted to the tibia by simultaneous pronation and knee extension may blanch or wring out vessels in the tendon and peritendon causing vascular impairment and subsequent degenerative changes in the Achilles tendon.” This “region of relative avascularity” extends from 2 to 6 cm above the insertion into the calcaneus, and is the common site for a rupture of the Achilles tendon. This makes it especially important to ensure very good blood flow as the body attempts to heal this condition.

Achilles “tendinopathy”

The most common cause of functional breakdown of the Achilles tendon is a biomechanical deficit that places excess stress on the tendon. Inflexibilities, weakness, and imbalances are noted throughout the lower extremity Kinetic Chain, into the pelvis and spine. In a study of 455 athletes with Achilles tendon injuries, Kvist discovered obvious biomechanical deficits in 60% of subjects. ⁴ In many cases, the major biomechanical problem underlying an Achilles tendon problem is excessive pronation.

Most injuries of the Achilles tendon are not due to a recent acute injury—they have actually developed gradually, over a period of weeks or months. These are “overuse” or “misuse” conditions and are caused by excessive and/or repetitive motion, often with poor biomechanics. The end result is a microtrauma injury—the body is unable to keep up with the repair and re-strengthening needs, so the tissue begins to fail and becomes symptomatic. If it is not very painful (or when the pain is eliminated by pain-killing drugs), continued stress can lead eventually to complete failure, with a resulting acute tear of the tendon.

Because the Achilles tendon insertion on the calcaneus is medial to the axis of the subtalar joint, the calf muscles are powerful supinators of the subtalar joint. Therefore, when excessive pronation occurs, the Achilles tendon is overstressed, and it eventually undergoes overuse degeneration and inflammation. This was described by Clement and his fellow investigators at the University of British Columbia in Vancouver, Canada. They explained how “pronation generates an obligatory internal tibial rotation which tends to draw the Achilles tendon medially. Through slow motion, high-speed cinematography we have seen that pronation produces a whipping action or bowstring effect in the Achilles tendon. This whipping action, when exaggerated, may contribute to microtears in the tendon, particularly in its medial aspect, and initiate an inflammatory response.” ⁵ These investigators believe that the control of functional overpronation with corrective orthotic devices is a necessary treatment for most patients with Achilles tendinitis.

Achilles Tendinitis/Tendinosis

It’s not surprising that abnormal biomechanics of the foot and ankle can cause problems with the largest tendon in the leg. Symptoms are usually described as diffuse pain in or around the back of the ankle (from the calf to the heel). The pain is aggravated by activity, especially uphill running or climbing stairs, and relieved somewhat by wearing higher-heeled shoes or boots. Palpation will find a tender thickening of the peritendon, and there could be crepitus during plantar and dorsiflexion. Often, a recent increase in activity levels (such as more stair-climbing) or a change in footwear is reported by the patient. The most useful (and highly predictive) clinical test is to find a tender area of intratendinous swelling that moves with the tendon and disappears when the tendon is put under tension.⁶

Macroscopically, overused Achilles tendon tissues examined at surgery are dull, slightly brown, and soft, in comparison to normal tendon tissue, which is white, glistening, and firm.⁷ There is a loss of collagen continuity and an increase in ground substance and cellularity, which is due to fibroblasts and myofibroblasts, and not inflammatory cells.⁸ This is the reason that anti-inflammatory strategies (such as NSAIDS drugs and corticosteroid injections) are not indicated for these conditions, and actually may interfere with tendon repair.⁹ We now know that the condition we usually have described as “tendinitis” is actually better understood as “tendinosis”, and is not due to inflammation, but an underlying degeneration of collagen tissues in response to mechanical overuse.¹⁰ This “new paradigm” will help to guide our management of all tendon problems, and provide more effective rehabilitation for Achilles tendons.

Two other factors have been recently reported—and they deal with drug side effects. Doctors of Chiropractic should be aware that the use of statin medications (cholesterol-lowering drugs)¹¹ and fluoroquinolones (a class of antibiotic drugs) ¹² have been reported to cause Achilles tendinopathy and rupture. Patients with Achilles tendon problems must always be asked about their drug regimens.

Conclusion

A combination of a change in activities and the use of custom-made functional orthotics has been found to be effective in most cases of Achilles tendinopathy. ¹³ Achilles tendinitis can be easily treated conservatively, and steroid injections, surgery, and casting are seldom used these days. One of the most important treatment methods is to reduce any tendency to pronate excessively. In addition to custom-made orthotics, runners should wear well-designed shoes which provide good heel stability with a small amount of additional heel lift. This will help to prevent Achilles tendon problems and is especially important in athletes running for more than a few miles at a time. Once any local inflammation that is present has been controlled, treatments to improve the blood flow to the region of relative avascularity are necessary.

The use of corrective orthotics can prevent many overuse problems from developing in the lower extremities. Investigation of foot and ankle biomechanics is a good idea in all patients, but especially for those who are recreationally active. Competitive athletes, in particular, must have regular evaluation of the alignment and function of their feet, in order to avoid potentially disabling injuries. As described above, most Achilles tendon problems develop from poor foot and ankle biomechanics, and control of pronation is needed to prevent recurrent injuries. ¹⁴ Custom-made functional orthotics are now available that can support the hindfoot, midfoot, and forefoot, thereby providing biomechanical control throughout the entire gait cycle.

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² Maffuli N, Kader D. Tendinopathy of tendo achillis. J Bone Joint Surg Br 2002; 84:1-8.

³ Carr AJ, Norris SH. The blood supply of the calcaneal tendon. J Bone Joint Surg Br 1989; 71:100-01.

⁴ Kvist M. Achilles tendon injuries in athletes. Ann Chir Gynaecol 1991:80:188-201.

⁵ Clement DB, et al. Achilles tendinitis and peritendinitis: etiology and treatment. Am J Sports Med 1984; 12:179-84.

⁶ Maffuli N, Kenward MG, Testa V, et al. Clinical diagnosis of Achilles tendinopathy with tendinosis. Clin J Sports Med 2003; 13:11-5.

⁷ Astrom M, Rausing A. Chronic Achilles tendinopathy: survey of surgical and histopathologic findings. Clin Orthop 1995; 316:151-64.

⁸ Khan KM, Cook JL, Bonar F, Harcourt P, Astrom M. Histopathology of common tendinopathies: update and implications for clinical management. Sports Med 1999; 27:393-408.

⁹ Almekinders LC, Temple JD. Etiology, diagnosis, and treatment of tendonitis: an analysis of the literature. Med Sci Sports Exerc 1998; 30:1183-90.

¹⁰ Khan KM, et al. Overuse tendinosis, not tendinitis. Part 1: a new paradigm for a difficult clinical problem. Phys Sportsmed 2000; 28:38-48.

¹¹ Chazerain P, Hayem G, Hamza S, et al. Four cases of tendinopathy in patients on statin therapy. Joint Bone Spine 2001; 68:430-3.

¹² Vanek D, Sexena A, Boggs JM. Fluoroquinolone therapy and achilles tendon rupture. J Am Podiatr Med Assoc 2003; 93:333-5.

¹³ Sorosky B, Press J, Plastaras C, Rittenberg J. The practical management of Achilles tendinopathy. Clin J Sport Med 2004; 14:40-4.

¹⁴ Busseuil C. et al. Rearfoot-forefoot orientation and traumatic risk for runners. Foot & Ankle Intl 1998; 19:32-7.