An Achilles tendon rupture is a complete or partial tear of the Achilles tendon, which connects the calf muscles (gastrocnemius and soleus) to the heel bone (calcaneus). It is one of the most common tendon ruptures in the lower limb.
Rupture typically presents suddenly during physical activity, causing pain, functional impairment, and often the feeling of being “kicked” in the back of the leg.
Because the Achilles tendon plays a critical role in push-off during gait, jumping, and propulsion, restoring its continuity and strength is key to regaining normal function.
Anatomy and Biomechanics
The Achilles tendon is formed by the merging tendinous portions of the gastrocnemius and soleus muscles. It inserts onto the posterior aspect of the calcaneal tuberosity.
The tendon has a twist as it descends, which helps with force transmission. The blood supply is relatively tenuous in the mid-substance region (approximately 2 to 6 cm proximal to the insertion), making this region more susceptible to degeneration and rupture.
There is no true tendon sheath; instead, the tendon is surrounded by a paratenon (a vascularized sheath-like covering) that facilitates gliding and supplies nutrition.
Mechanically, the Achilles tendon must withstand high loads during activities such as running or jumping, forces exceeding several times body weight pass through it. Sudden eccentric loading or abrupt dorsiflexion while contracting can exceed its tensile strength and precipitate rupture.
Epidemiology
Achilles tendon ruptures account for a substantial fraction of major tendon injuries in the lower extremities. Estimates of incidence vary; figures from 11 to 37 per 100,000 population per year have been reported.
Men are disproportionately affected compared to women (often 2- to 12-fold more frequent), and there tends to be a peak in incidence in middle age (third to fifth decades) in physically active individuals. Some older age peaks may represent spontaneous rupture of degenerative tendons.
Risk Factors
Intrinsic and extrinsic risk factors contribute:
- Preexisting tendinopathy or degenerative changes in the tendon
- Overuse, sudden increases in activity, or inadequate conditioning/preparation
- Use of fluoroquinolone antibiotics, especially ciprofloxacin and levofloxacin, has been associated with tendon injury
- Corticosteroid use (systemic or local)
- Systemic illnesses such as diabetes mellitus, hyperparathyroidism, chronic renal disease, inflammatory arthritides, and connective tissue disorders
- Mechanical or anatomic factors: limited calf flexibility, poor muscle strength, foot alignment (e.g. cavus foot)
Pathophysiology
Over time, the tendon may undergo degenerative microscopic changes (mucoid degeneration, collagen disorganization, neovascularity), especially in the watershed zone, weakening the tendon structure.
Under sudden high tensile stress, for example, abrupt plantarflexion contracture against dorsiflexion, the weakened region may fail, resulting in a rupture.
Depending on the site, the tear may be mid-substance (most common), at the musculotendinous junction, or near insertion (less common).
Immediately after rupture, there is bleeding, inflammation, and retraction of the tendon ends. Over time, scar tissue may attempt to bridge the gap, but this remodeling often results in weaker tissue if untreated or improperly rehabilitated.
Clinical Presentation
History
Patients often report a sudden onset of pain in the posterior heel or calf during an activity such as pushing off, jumping, or sudden acceleration. Many hear or feel a “pop” or snapping sensation. Some describe the feeling as being kicked or struck in the back of the leg.
Sometimes, there may have been prior symptoms of tendonitis or tendon degeneration.
Physical Examination
Key findings may include:
- A palpable gap or defect in the tendon about 2 to 6 cm proximal to the insertion
- Swelling, ecchymosis, and tenderness over the rupture site
- Weakness or absence of active plantarflexion
- Inability to stand on tiptoes on the affected side
- Positive Thompson (squeeze) test: when the calf is squeezed, there is minimal or no plantarflexion of the foot in a ruptured tendon scenario
- Occasionally, increased passive ankle dorsiflexion
It is possible to miss or misdiagnose the rupture initially, as up to 20–25% of injuries are misattributed to ankle sprain.
Diagnostic Evaluation
While a clinical exam is often sufficient for diagnosis, imaging can confirm the extent and location and rule out other injuries.
Imaging
- Plain radiographs (lateral and axial heel views) may show soft tissue swelling or avulsion fragments near the calcaneus, but usually don’t directly show the tendon rupture.
- Ultrasound (real-time) can identify the defect, gap length, and tendon end separation.
- Magnetic resonance imaging (MRI) is very useful for precise evaluation of tendon integrity, the gap, degree of tendon retraction, and for surgical planning.
Imaging is especially helpful when the diagnosis is uncertain clinically or for preoperative mapping.
Treatment
The major goals are to restore tendon continuity, approximate normal length and tension, allow early rehabilitation, minimize re-rupture risk, and restore full function.
Deciding between nonoperative and surgical management depends on patient factors (age, activity level, comorbidities), rupture characteristics (gap size, tissue quality, location), and risk of complications.
Nonoperative (Conservative) Management
Historically, conservative treatment involved immobilization in plantarflexion (casting) for weeks. More modern functional bracing/rehabilitation protocols allow earlier controlled motion and gradual loading.
Recent trials suggest that in selected patients, nonoperative treatment with accelerated rehabilitation yields functional outcomes comparable to surgical repair, albeit with a somewhat increased risk of re-rupture.
Advantages: no surgical risks (infection, wound complications, nerve injury)
Disadvantages: higher re-rupture risk in poorly selected cases, possible elongation of the tendon, and slower return to high-demand activity
Surgical Management
Surgical repair aims to reduce the tendon ends and re-establish proper tension. Techniques include:
- Open repair
- Minimally invasive or percutaneous repair
- Augmentation with grafts or biological materials in chronic or large-gap cases
Surgical treatment generally offers lower rates of re-rupture, earlier strength recovery, and better ability to return to high-demand activities. However, it carries risks of wound complications, infection, nerve injury, and scar adhesion.
Some newer approaches involve biologic augmentation (e.g., platelet-rich plasma, scaffolds) and improved surgical techniques, though evidence remains evolving.
Choosing the Approach
Important considerations:
- Patient’s age, activity goals, and comorbidities
- Size of tendon gap, tendon end quality
- Time since rupture (acute vs delayed/chronic)
- Risk tolerance for surgical complications
- Ability to commit to rehabilitation
When rehabilitation resources are strong and patients are appropriately selected, nonoperative management becomes a more viable option, even in many athletic individuals.
Rehabilitation and Post-Treatment Care
After the initial repair or during conservative treatment, rehabilitation is critical to success.
- Early controlled motion (within safe limits) is emphasized in modern protocols
- Weight-bearing is usually progressed gradually, often reaching full weight-bearing by 6 to 8 weeks (depending on repair stability)
- Strengthening of calf muscles, proprioception, and functional training
- Close monitoring for tendon elongation, scar formation, or weakness
- Return to sport is typically delayed until 6 to 12 months, depending on recovery
Consistent, supervised rehabilitation is as important as the initial treatment choice for long-term outcomes.
Complications and Prognosis
Possible Complications
- Re-rupture of the tendon (higher in nonoperative treatment if protocols are lax)
- Tendon elongation leading to weakness or altered gait mechanics
- Adhesion or scar tissue limiting motion
- Wound problems, infection (in surgical cases)
- Nerve injury (e.g. sural nerve)
- Deep vein thrombosis, especially in immobilization periods
Prognostic Factors
Better outcomes tend to align with:
- Younger age, good tissue quality
- Short interval to treatment
- Small tendon gap, minimal degeneration
- Strong rehabilitation compliance
- Use of techniques minimizing elongation
Overall, when well treated, many patients regain a high level of function. However, deficits (such as reduced calf strength or endurance) may persist, and return to pre-injury performance levels may not always be achieved, especially in elite athletes.
Prevention and Patient Education
- Proper conditioning, stretching, and strength training of calf-ankle complex
- Gradual increments in training intensity, avoiding sudden overload
- Awareness of risk associated with fluoroquinolone antibiotics and corticosteroids in susceptible individuals
- Early reporting and assessment of tendon pain or degeneration symptoms
- Maintaining tendon health via balanced load, rest, and recovery
References
Weinfeld SB. Achilles tendon disorders. Med Clin North Am. 2014 Mar;98(2):331-8. doi: 10.1016/j.mcna.2013.11.005. PMID: 24559878.
Maffulli N, Via AG, Oliva F. Chronic Achilles Tendon Disorders: Tendinopathy and Chronic Rupture. Clin Sports Med. 2015 Oct;34(4):607-24. doi: 10.1016/j.csm.2015.06.010. Epub 2015 Jul 31. PMID: 26409586.
Patch DA, Andrews NA, Scheinberg M, Jacobs RA, Harrelson WM, Rallapalle V, Sinha T, Shah A. Achilles tendon disorders: An overview of diagnosis and conservative treatment. JAAPA. 2023 Oct 1;36(10):1-8. doi: 10.1097/01.JAA.0000977720.10055.c4. PMID: 37751268.
Bonanno J, Cheng J, Tilley D, Abutalib Z, Casey E. Factors Associated With Achilles Tendon Rupture in Women’s Collegiate Gymnastics. Sports Health. 2022 May-Jun;14(3):358-368. doi: 10.1177/19417381211034510. Epub 2021 Jul 31. PMID: 34338076; PMCID: PMC9112717.
Mansfield K, Dopke K, Koroneos Z, Bonaddio V, Adeyemo A, Aynardi M. Achilles Tendon Ruptures and Repair in Athletes-a Review of Sports-Related Achilles Injuries and Return to Play. Curr Rev Musculoskelet Med. 2022 Oct;15(5):353-361. doi: 10.1007/s12178-022-09774-3. Epub 2022 Jul 9. PMID: 35804260; PMCID: PMC9463425.
