Sports Medicine in Greek Mythology: A Complete Guide to Achilles Tendinopathy

In Greek mythology, the legendary warrior Achilles was said to be invulnerable except at his heel. The Iliad records that he died when an arrow pierced his Achilles tendon, which is why an Achilles’ heel has become a byword for a person’s main weakness.

An Achilles tendon rupture is different from Achilles tendinopathy. Achilles tendinopathy is an overuse injury of the Achilles tendon that causes pain in the back of the calf and the heel. Its synonyms include Achilles tendinosis and Achilles tendinopathy. A recent issue of the journal JOSPT gathered several training-related studies into an infographic that is well worth reading.

Epidemiology

• It accounts for about 6.5% to 18% of running injuries, and up to 4% of patients in sports medicine clinics.
• Athletes who take part in running and jumping sports are especially prone to injury, and the lifetime incidence in competitive runners may be as high as 50%.
• The most common site is the mid-portion (80 to 90%); purely insertional disease is relatively rare (5%).

Pathophysiology

• High-risk zones:
  • The musculotendinous junction
  • The region of the distal Achilles tendon 2 to 6 cm above the insertion, a relatively hypovascular area with little paratenon and intratendinous blood supply
• Disruption of tendon structure:
  • Chronic intratendinous degeneration, collagen fiber disarray, and increased mucoid matrix
  • Neovascularization and sympathetic nerve ingrowth along the ventral surface of the Achilles tendon
• Most notably, there is a sequential loss of the tendon tissue’s structure; tendon bundles may show increased waviness, and separation of the bundles is often seen.
• Some studies argue for using the term partial tear when there are large areas of apparently discontinuous bundles, but this is controversial. Another notable feature is increased vascularization; these vessels are thought to be newly formed, characterized by a tortuous phenotype and small lumens, and are considered part of a failed healing response.
• The vessels may originate from the fat tissue on the ventral side of the tendon. Recent studies show that in the paratenon tissue outside the ventral tendon there are multiple sensory and sympathetic nerves closely associated with the vessels, while there are very few nerves inside the tendon itself.

Risk factors

• Training errors: increases in distance, intensity, or duration of activity
• Wearing worn or old shoes
• Insufficient flexibility, especially a tight heel cord
• A higher body mass index (BMI)
• Hypertension and diabetes
• Hypothyroidism
• Older patients: reduced tensile strength and increased stiffness of the tendon
• Malalignment of the leg (excessive genu valgum, external tibial torsion) or the ankle/foot (flatfoot)
• Medications:
  • Quinolone antibiotics: recent use of these antibiotics has been associated with an increased risk of Achilles tendinopathy and rupture
  • Long-term corticosteroid use
  • Statins are considered a possible cause of tendinopathy, confirmed in some animal models

Commonly associated conditions

• Retrocalcaneal bursitis
• Posterior ankle impingement syndrome
• Superficial Achilles bursitis (Haglund deformity)
• Achilles tendon rupture: chronic tendon changes may lead to rupture

History

• Initial pain that eases after use but returns with continued or repeated use suggests an overuse injury.
• Morning stiffness is a hallmark of Achilles tendinopathy.
• Training errors are a factor in most cases.
• Worn or old shoes: shoes should be replaced every 250 to 500 miles of use, because the cushioning material breaks down over time and loses its shock absorption.
• Patients may report weakness and intermittent swelling.

Physical examination

• Pain and stiffness 2 to 6 cm above the insertion of the Achilles tendon
• Pain with running, especially during sprinting
• Tenderness of the distal Achilles tendon 2 to 6 cm above the insertion:
  • Tenderness near the insertion suggests insertional Achilles tendinopathy or bursitis
• Thickening of the distal Achilles tendon in chronic cases
• Tenderness on resisted plantar flexion, weakness with repeated single-leg heel raises, crepitus on ankle motion, and reduced ankle dorsiflexion (due to a tight heel cord)
• A negative Simmonds-Thompson test: squeezing the calf produces normal passive plantar flexion:
  • A positive test (no plantar flexion when the calf is squeezed) suggests a complete Achilles tendon rupture

Differential diagnosis

• Retrocalcaneal bursitis
• Superficial Achilles bursitis
• Calcaneal apophysitis in adolescents (Sever disease)
• Haglund deformity: a prominent superior tubercle of the calcaneus
• Achilles tendon rupture
• Gastrocnemius-soleus tear
• Plantaris tendinopathy
• Overuse myositis
• Chronic exertional compartment syndrome
• Os trigonum irritation or posterior ankle impingement syndrome
• Vascular/neurogenic intermittent claudication
• Deep vein thrombosis
• Hematoma
• Infection

Diagnostic tools

• Imaging is usually not needed initially; if another underlying injury is suspected (such as a fracture or tumor) or there is no response to appropriate treatment, an X-ray should be obtained.
• A standard ankle X-ray series (anteroposterior, lateral, and mortise views) may show tendon calcification; however, the presence of calcification does not change initial treatment.
• Ultrasound has become a powerful diagnostic tool in recent years: it is simple and useful, but requires an experienced clinician to operate.
  • It can show hypoechoic areas, intratendinous calcification, fiber disarray, fusiform expansion, partial-thickness intratendinous tears, and neovascularization, which may appear in Achilles tendinopathy.
  • Degenerative changes are visible in about 60% of healthy, uninjured people, and those with high activity levels are more likely to have these changes.
  • Studies show these abnormalities are associated with an increased future risk of tendinopathy, but resolution of the changes does not necessarily correlate with resolution of symptoms.
• MRI
  • Because of its three-dimensional perspective and excellent soft-tissue contrast, MRI can provide high-quality images of the Achilles tendon.
  • A normal, healthy Achilles tendon appears dark on MRI, with tightly and parallel-arranged collagen and low intrinsic water content, whereas a pathological tendon shows tendon thickening or an abnormal increase in water signal.
  • MRI cannot be used to assess blood flow.

Initial treatment

• Relative rest: in particular, cut back on sprinting, speed training, and hill or stair running, and overall reduce running intensity, duration, and/or frequency.
• Ice after activity; adequate warm-up before activity
• Wear appropriate athletic shoes
• Stretching: make sure the athlete follows an appropriate training program, including pre-activity warm-up and post-activity cool-down routines
• Prolotherapy injections: usually two to three or more injection treatments are needed, spaced 2 to 8 weeks apart, with some degree of improvement in some patients
• Anti-inflammatory drugs (NSAIDs): may help relieve pain in acute symptoms, but there is a lack of evidence for benefit in chronic cases.
• Nitroglycerin: topical nitroglycerin (patch or ointment) has been shown to reduce pain during daily activities in both the acute and chronic phases, and may help improve tendon strength in the chronic phase

Additional treatment

• The main treatment methods are stretching and calf-strengthening exercise, to improve flexibility and to promote tendon-tissue repair through mechanotransduction.
• Eccentric strengthening exercise: mainly emphasizing the slow negative phase during a single-leg squat, which has been shown to reduce pain and improve function. Using a 25-degree decline board during these exercises may provide additional clinical benefit for athletes
• Correcting biomechanical abnormalities (where possible) and/or training errors
• Wearing a patellar tendon strap has been shown to reduce local tendon strain and may help reduce symptoms during activity
• PRP injections: the evidence is currently inconsistent; in chronic tendinopathy, for athletes, saline and PRP injections show no significant difference in athletic performance (both improved)
• Shockwave therapy: there is some research support; compared with training alone, shockwave shows a significant difference in improving tendinopathy pain

Surgery

• Open repair or closed techniques
  • Compared with non-surgical treatment, surgery has a lower re-rupture rate, especially in the absence of early functional rehabilitation training
  • It enhances the recovery of calf strength and reduces loss of push-off power
  • Surgical complications include infection, deep vein thrombosis (DVT), pulmonary embolism, and death
  • Other post-operative risks include delayed healing, scar adhesion, infection, persistent limp, over-lengthening, and sural nerve injury in percutaneous techniques
  • Surgery is usually recommended for high-level athletes, for patients returning to high-risk activities (such as basketball, tennis, soccer, and sprinting), and for treating a re-rupture

Rehabilitation training programs

• Activity-based rehabilitation guidance for non-surgical treatment is mainly for people aged 18 to 65 with unilateral mid-portion Achilles tendinopathy symptoms for more than 3 months. It includes:

• The Alfredson Program, used to treat mid-portion Achilles tendinopathy

  • Source: based on the study by Alfredson et al. published in 1998 in the American Journal of Sports Medicine (Am J Sports Med), and the study by Habets et al. in 2021 in the Orthopaedic Journal of Sports Medicine (Orthop J Sports Med)
  • Exercise program
    • Frequency: twice a day, seven days a week, for 12 weeks
    • Repetitions each time: 3 sets of 15 repetitions per exercise (15 repetitions each for the straight-knee and bent-knee movements)
  • Straight-knee movement:
    • Start position: use the unaffected leg to raise the body to full ankle dorsiflexion
    • Exercise movement: use the affected leg to lower the body weight to full ankle dorsiflexion
  • Bent-knee movement:
    • Start position: use the unaffected leg to raise the body to full ankle dorsiflexion
    • Exercise movement: with a bent knee, use the affected leg to lower the body weight to full ankle dorsiflexion
  • Outcome: after one year, 50% of patients felt significantly or very significantly improved (this is a trial result and does not predict any individual’s outcome)

• The Heavy Load and Slow Resistance Program, used to treat mid-portion Achilles tendinopathy

  • Program background: based on the study by Beyer et al. published in 2015 in the American Journal of Sports Medicine (Am J Sports Med)
  • Exercise program
    • Frequency: 3 times per week, 3 or 4 sets each time, with 2 to 3 minutes of rest between sets and 5 minutes between exercises, for 12 weeks
    • Repetitions each time: a 3-second concentric and eccentric phase per exercise (6 seconds per repetition)
  • Exercise details
    • Exercise A: straight-knee heel raise on a leg-press machine
    • Exercise B: straight-knee heel raise using a barbell on the shoulders with the forefoot on a weight plate
    • Exercise C: bent-knee heel raise on a seated calf machine
  • Weekly progression:
    • Week 1: 3 sets of 15 repetition maximum (3 x 15RM)
    • Weeks 2 to 3: 3 sets of 12 repetition maximum (3 x 12RM)
    • Weeks 3 to 5: 4 sets of 10 repetition maximum (4 x 10RM)
    • Weeks 6 to 8: 4 sets of 8 repetition maximum (4 x 8RM)
    • Weeks 9 to 12: 4 sets of 6 repetition maximum (4 x 6RM)
  • Outcome: high treatment satisfaction (96% at 52 weeks; this is a trial result and does not predict any individual’s outcome)

• The Silbernagel Program, used to treat mid-portion Achilles tendinopathy

  • Source: based on the study by Silbernagel et al. published in 2007 in the American Journal of Sports Medicine (Am J Sports Med)
  • Exercise program frequency: depending on the stage, from daily to 2 to 3 times per week, for 6 months
  • Exercise details
    • Exercise A: two-leg concentric and eccentric heel raise
    • Exercise B: single-leg eccentric heel raise (returning to the start position with both legs)
    • Exercise C: single-leg concentric and eccentric heel raise
    • Exercise D: two-leg seated heel raise
  • Exercise progression
    • Stage one (weeks 1 to 2): perform A, B, C, D daily, 3 sets of 10 to 15 repetitions each.
    • Stage two (weeks 2 to 5): perform A, B, C, D, A daily, 3 sets of 15 repetitions each, adding a faster, rebounding movement to the final A.
    • Stage three (weeks 3 to 12): perform B, C, D, A daily, 3 sets of 15 repetitions each, adding weight to B and C, and adding a faster, rebounding movement to the final A with 20 repetitions per set.
    • Stage four (week 12 to month 6): perform B, C, A 2 to 3 times per week, 3 sets of 15 repetitions each, adding weight to B and C, and adding a faster, rebounding movement to the final A with 20 repetitions per set.
  • Notes
    • Pain-monitoring model: continue exercising while pain is at or below 5 out of 10, unless pain does not ease soon after exercise, is still present the next morning, or pain and stiffness increase week over week
    • Progression management: gradually increase load and reduce the number of repetitions
  • Outcome: after one year, 77% of patients significantly improved (this is a trial result and does not predict any individual’s outcome)

References

Managing Achilles Tendinopathy (jospt.org)

Front Immunol. 2023 Aug 16:14:1193835.

Sports Med Open. 2022 May 13;8(1):68.

PM R.2023 Nov;15(11):1493-1506. doi: 10.1002/pmrj.12965.