A note on this column: This article is general medical information, not a description of a service offered at this practice. Dr. Ishiguro's surgical practice is focused on hip and knee conditions — he does not treat or perform surgery for Achilles tendinopathy or Achilles tendon rupture. This column is written to help readers understand two common tendon problems and know when and how to seek the right specialist, typically a foot-and-ankle orthopaedic surgeon, sports medicine physician, or physical therapist.
One tendon, two very different problems
The Achilles tendon is the thick band of tissue connecting the calf muscles to the heel bone, and it is the strongest tendon in the human body — capable of withstanding forces several times body weight during running and jumping. Precisely because it's under such high, repetitive load, it's also one of the most commonly injured tendons in active adults.
Two distinct conditions account for most Achilles problems, and it's worth being clear about the difference from the start, because they look and behave very differently. Achilles tendinopathy is a gradual, overuse-related condition — pain and stiffness that build up over weeks or months, usually in people who run or jump regularly, or who have recently increased their activity level. Achilles tendon rupture is an acute, often sudden and complete tear, classically described by patients as feeling like being kicked or shot in the back of the calf, frequently during a forceful push-off movement in sport.
Quick distinction
- Tendinopathy — gradual onset, aching pain that's often worse first thing in the morning or after rest, tenderness and thickening 2–6 cm above the heel, tendon remains intact
- Rupture — sudden onset, often an audible pop, immediate sharp pain, difficulty pushing off or rising onto the toes, a palpable gap may be felt in the tendon
Achilles tendinopathy: why it develops
Tendinopathy is now understood primarily as a failed healing response to repetitive overload, rather than a purely inflammatory process — which is why the older term "tendinitis" has largely fallen out of use in the clinical literature. Under repeated mechanical stress, the tendon's collagen structure develops small areas of disorganisation and the tendon gradually thickens in the affected zone, most often in the mid-portion 2–6 cm above where it attaches to the heel, though it can also occur right at the insertion.
Risk factors include a rapid increase in running volume or intensity, poor calf flexibility, tight or weak calf muscles, wearing worn-out or inadequately supportive footwear, obesity, and certain medications — most notably fluoroquinolone antibiotics and, less commonly, prolonged corticosteroid use, both of which have been associated with a higher risk of tendon problems including rupture. Age also matters: tendinopathy tends to affect active adults in their 30s to 50s, an age range where tendon tissue has somewhat reduced capacity to adapt to load compared with younger athletes.
Achilles rupture: who it happens to and why
Somewhat counterintuitively, Achilles rupture is most common not in elite athletes but in what's sometimes called the "weekend warrior" — a person in their 30s to 50s who plays recreational sport (badminton, basketball, and tennis are frequently cited in the literature) without a regular training base. The classic mechanism is a forceful, unexpected loading of the tendon: pushing off suddenly, an abrupt change of direction, or an unexpected dorsiflexion of the foot when the calf is contracting.
A tendon that already has some degree of underlying degeneration from pre-existing (sometimes unnoticed) tendinopathy is thought to be more vulnerable to complete rupture, which is one reason persistent Achilles pain shouldn't be ignored even when it isn't severe.
How each is diagnosed
Achilles tendinopathy is usually diagnosed clinically: localised tenderness and thickening along the tendon, pain reproduced with resisted plantarflexion (pushing the foot down against resistance), and a history consistent with overuse. Ultrasound or MRI can confirm the diagnosis and show the characteristic thickening and altered fibre pattern, and imaging is particularly useful when the diagnosis is uncertain or symptoms haven't responded to initial treatment.
Rupture is also primarily a clinical diagnosis, most reliably confirmed with the Thompson test — squeezing the calf with the patient lying face down and knee bent; in an intact tendon, this squeeze causes the foot to point downward, while an absent response strongly suggests a complete rupture. A palpable gap in the tendon and inability to stand on tiptoes on the affected side are other classic findings. Ultrasound or MRI can confirm the diagnosis and characterise the size of the gap between torn tendon ends, which can help guide the choice between treatment approaches.
A note on missed diagnosis: A meaningful proportion of Achilles ruptures are missed at the first medical visit, in part because some patients can still walk — awkwardly — and even weakly plantarflex the foot using secondary muscles, despite a complete tear. Any sudden "pop" in the calf with acute weakness pushing off the foot warrants prompt evaluation rather than being assumed to be a strain.
What the evidence says: treating tendinopathy
The 2024 revision of the clinical practice guideline on midportion Achilles tendinopathy from the Academy of Orthopaedic Physical Therapy, a systematic update of the evidence since 2018, is one of the most current, comprehensive reference points available on this condition.
What the evidence shows: The 2024 guideline concludes that tendon-loading exercise remains the intervention with the strongest evidence base for midportion Achilles tendinopathy, and recommends it as first-line treatment. Eccentric-loading protocols (lengthening the calf muscle under tension, such as slowly lowering the heel off a step) have particularly strong supporting evidence, though heavy slow resistance training has also shown comparable benefit in more recent trials and may be easier for some patients to perform consistently. The guideline also highlights growing evidence that patient education — helping patients understand that tendinopathy is a gradual, load-management problem rather than a structural injury requiring rest — is an effective and low-risk component of care in its own right (Chimenti et al., J Orthop Sports Phys Ther, 2024).
Commonly used treatments for tendinopathy
- Activity modification — temporarily reducing (not necessarily stopping) the aggravating load while symptoms settle
- Eccentric or heavy slow-resistance calf-loading exercise — the evidence-based cornerstone of treatment, typically over 8–12 weeks
- Footwear changes and, in some cases, a heel lift — to reduce strain at the tendon insertion
- Extracorporeal shockwave therapy — supported by some trial evidence, generally used when exercise alone hasn't been sufficient
- Platelet-rich plasma (PRP) injection — evidence remains mixed; recent systematic reviews have generally not found a clear, clinically meaningful benefit over control treatments
- Surgery (debridement or tendon repair) — reserved for the minority of patients who don't improve after a genuine, sustained course of exercise-based treatment, usually at least several months
What the evidence says: treating rupture
For acute complete rupture, the central clinical question for decades has been whether surgical repair produces meaningfully better outcomes than nonoperative treatment (immobilisation followed by protected, progressive weight-bearing in a boot). This has been directly studied in large randomised trials.
What the evidence shows: A large multicentre randomised trial of 526 patients directly compared nonoperative treatment, open surgical repair, and minimally invasive surgery. At 12 months, there was no statistically significant difference between the three groups in the primary patient-reported outcome measure (Achilles Tendon Total Rupture Score); mean changes from baseline were −17.0, −16.0, and −14.7 points respectively (P=0.57) (Myhrvold, Brouwer, Andresen et al., N Engl J Med, 2022). A separate 2024 meta-analysis pooling 14 randomised trials and 1,399 patients found that surgical treatment was associated with a significantly lower re-rupture rate (roughly 3% vs. roughly 10% with nonoperative treatment) and a somewhat faster return to work, but also a significantly higher rate of other complications, such as wound problems and nerve irritation (about 19% vs. about 6%) (Fan, Hu, Zhou, Fu, Front Surg, 2024).
| Approach | Re-rupture risk | Other complications | Typical use |
|---|---|---|---|
| Nonoperative | Somewhat higher | Lower | Often preferred for lower-demand patients, or when surgical risk factors (diabetes, smoking, poor skin condition) are present |
| Open surgical repair | Lower | Higher (wound, nerve) | Often considered for younger, highly active patients, or larger tendon gaps |
| Minimally invasive surgery | Lower | Intermediate | Aims to balance the lower re-rupture risk of surgery with reduced wound complications |
The clinical takeaway from this body of evidence is that neither approach is categorically "better" — the decision involves a genuine trade-off between a modestly higher chance of re-rupture with nonoperative care and a modestly higher chance of a surgical complication, and reasonable specialists differ on how they weigh this for an individual patient's age, activity goals, and general health. Functional (early motion, progressive weight-bearing) rehabilitation protocols, rather than prolonged rigid casting, are now standard after both nonoperative and operative treatment and have contributed to narrowing the outcome gap between the two approaches compared with older studies.
When to see a specialist
Persistent Achilles pain that doesn't improve after a couple of weeks of relative rest, or that recurs each time activity resumes, is worth a proper evaluation rather than working through it indefinitely — particularly because unaddressed tendinopathy may increase the risk of a subsequent rupture. Any sudden, sharp calf pain with an audible pop or a feeling of being struck from behind, especially with difficulty rising onto the toes, should be assessed urgently, ideally within days, since the timing and gap size can influence treatment options.
References (PubMed / Journal)
Chimenti RL, Similton E, Alrwaily M, et al. Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision – 2024. Clinical Practice Guidelines Linked to the International Classification of Functioning, Disability, and Health from the Academy of Orthopaedic Physical Therapy of the American Physical Therapy Association. J Orthop Sports Phys Ther. 2024;54(12):CG1-CG32. DOI: 10.2519/jospt.2024.0302
Myhrvold SB, Brouwer EF, Andresen TKM, et al. Nonoperative or Surgical Treatment of Acute Achilles' Tendon Rupture. N Engl J Med. 2022;386(15):1409-1420. DOI: 10.1056/NEJMoa2108447
Fan L, Hu Y, Zhou L, Fu W. Surgical vs. nonoperative treatment for acute Achilles' tendon rupture: a meta-analysis of randomized controlled trials. Front Surg. 2024;11:1483584. DOI: 10.3389/fsurg.2024.1483584