Achilles tendinitis

Achilles tendinitis is a common overuse injury of the lower limb, characterized by pain and inflammation of the Achilles tendon. It frequently affects athletes and active individuals, leading to discomfort and limitations in mobility. Early recognition and management are essential to prevent progression and complications.

Definition

Achilles tendinitis is defined as inflammation and degeneration of the Achilles tendon, typically resulting from repetitive microtrauma. It should be distinguished from Achilles tendinopathy, which refers to chronic degenerative changes without significant inflammation, and from Achilles tendon rupture, which is an acute complete or partial tear of the tendon.

Anatomy of the Achilles Tendon

Tendon Structure

The Achilles tendon is the strongest and thickest tendon in the human body, connecting the gastrocnemius and soleus muscles to the calcaneus. Key structural features include:

• Fibers and composition: Composed mainly of type I collagen arranged in parallel bundles providing tensile strength.
• Vascular supply: Relatively poor blood supply, particularly in the mid-portion of the tendon, which contributes to delayed healing.
• Innervation: Richly innervated with sensory and proprioceptive fibers, which mediate pain and stretch sensation.

Relationship to Surrounding Structures

The Achilles tendon interacts with multiple anatomical structures that influence its function and vulnerability to injury:

• Calcaneus insertion: The tendon inserts into the posterior aspect of the calcaneus, transmitting forces from the calf muscles.
• Muscle-tendon junctions: Connects to the gastrocnemius and soleus muscles, which generate plantarflexion strength.
• Paratenon and bursa: The tendon is surrounded by the paratenon, a connective tissue sheath, and the retrocalcaneal bursa, which reduce friction during movement.

Etiology and Risk Factors

Achilles tendinitis typically results from repetitive stress and strain on the tendon. Several factors contribute to its development, including intrinsic patient characteristics and external stressors.

• Overuse and repetitive strain: Activities involving running, jumping, or sudden acceleration increase tendon load.
• Biomechanical abnormalities: Flat feet, high arches, and abnormal gait patterns can alter tendon loading.
• Age and degenerative changes: Tendon elasticity decreases with age, making it more susceptible to injury.
• Medications: Fluoroquinolone antibiotics and systemic corticosteroids may increase tendon fragility.
• Sports and occupational factors: Athletes in running, basketball, or soccer, and occupations involving prolonged standing or heavy lifting are at higher risk.
• Previous injuries: Prior tendon microtears or ankle injuries can predispose to recurrent tendinitis.

Pathophysiology

The development of Achilles tendinitis involves both inflammatory and degenerative processes, often resulting from cumulative microtrauma that exceeds the tendon’s capacity to repair.

• Inflammatory processes vs degenerative changes: Acute overuse may trigger inflammation, while chronic repetitive stress leads to collagen disorganization and tendon degeneration.
• Microtears and collagen degeneration: Repeated loading can cause small tears in tendon fibers, weakening the structural integrity over time.
• Role of vascularity in healing: Poor blood supply, particularly in the mid-portion of the tendon, contributes to delayed healing and persistent symptoms.

Clinical Presentation

Symptoms

Patients with Achilles tendinitis usually report pain and discomfort that may worsen with activity. Common symptoms include:

• Pain along the tendon: Often located 2–6 cm above the calcaneal insertion, aggravated by running or jumping.
• Stiffness: Particularly noticeable in the morning or after periods of inactivity.
• Swelling or thickening: Localized swelling may be present over the tendon.

Signs

• Tenderness on palpation: Pain is elicited when the tendon is palpated along its course.
• Thickened tendon or nodularity: Chronic tendinitis may result in palpable irregularities.
• Crepitus or limited ankle movement: Patients may report a crackling sensation during movement and reduced flexibility.

Diagnosis

Clinical Examination

Diagnosis primarily relies on physical examination, supported by functional tests to assess tendon integrity and function.

• Observation: Inspection for swelling, redness, or asymmetry in the posterior ankle region.
• Palpation: Assessment of tenderness, thickening, and nodules along the tendon.
• Functional tests: Single-leg heel raise and calf-squeeze tests to evaluate pain and functional limitation.

Imaging

Imaging is useful when diagnosis is uncertain or to evaluate the severity of tendon involvement.

• Ultrasound: Detects tendon thickening, tears, and neovascularization.
• MRI: Provides detailed visualization of tendon structure, degeneration, and surrounding soft tissues.
• X-ray: Used primarily to rule out calcaneal bone abnormalities or bone spurs that may contribute to tendon irritation.

Management

Conservative Treatment

Most cases of Achilles tendinitis respond well to non-surgical management aimed at reducing pain and promoting tendon healing.

• Rest and activity modification: Reducing or avoiding activities that exacerbate tendon stress.
• Ice therapy: Application of cold packs to reduce pain and inflammation.
• Physical therapy and stretching exercises: Eccentric calf strengthening and tendon mobilization to restore function.
• Orthotics and heel lifts: Correct biomechanical abnormalities and reduce strain on the tendon.
• Extracorporeal shockwave therapy: May be used in chronic cases to stimulate tendon healing.

Pharmacological Management

• NSAIDs: Nonsteroidal anti-inflammatory drugs for short-term pain relief.
• Corticosteroid injections: Used cautiously due to risk of tendon weakening or rupture.

Surgical Management

Surgery is reserved for patients who do not improve with conservative measures after several months or have severe tendon degeneration.

• Indications for surgery: Persistent pain, chronic tendinopathy, or partial tendon tears.
• Open vs minimally invasive repair: Techniques vary from open debridement and repair to percutaneous or endoscopic approaches.
• Postoperative rehabilitation: Gradual return to activity with physical therapy to restore strength and flexibility.

Complications

If untreated or improperly managed, Achilles tendinitis can lead to serious complications affecting mobility and tendon integrity.

• Rupture of the Achilles tendon: Complete or partial tear resulting from chronic degeneration or acute trauma.
• Chronic pain or tendinopathy: Persistent discomfort and functional limitation may occur even with treatment.
• Calcification or bursal formation: Development of bone spurs or retrocalcaneal bursitis may exacerbate symptoms.
• Recurrence or persistent disability: Repeated overuse or incomplete rehabilitation may result in recurrent tendinitis or long-term functional impairment.

Prevention

Preventive strategies for Achilles tendinitis focus on reducing tendon stress and improving overall lower limb mechanics.

• Proper footwear and training techniques: Use shoes that provide adequate heel support and cushioning; avoid sudden increases in activity intensity.
• Gradual increase in activity: Progress training volume and intensity slowly to allow the tendon to adapt.
• Regular stretching and strengthening exercises: Eccentric calf exercises and flexibility routines help maintain tendon resilience.
• Addressing biomechanical abnormalities: Use orthotics or corrective interventions for flat feet, high arches, or gait abnormalities.

Prognosis

The prognosis for Achilles tendinitis is generally favorable with appropriate management, although recovery may vary depending on severity and patient factors.

• Factors influencing recovery: Age, degree of tendon degeneration, compliance with rehabilitation, and presence of comorbidities can affect outcomes.
• Expected outcomes: Most patients respond well to conservative treatment within a few months, while surgical intervention is reserved for refractory cases.
• Long-term functional considerations: With proper rehabilitation, most individuals regain full strength and mobility, although chronic tendinopathy may persist in some cases.

References

1. Magnussen RA, Dunn WR, Thomson AB. Nonoperative treatment of midportion Achilles tendinopathy. J Bone Joint Surg Am. 2009;91(4):841-849.
2. Khan KM, Cook JL, Bonar F, Harcourt P, Astrom M. Histopathology of common tendinopathies. Update and implications for clinical management. Sports Med. 1999;27(6):393-408.
3. Maffulli N, Kader D. Tendinopathy of tendo Achilles. J Bone Joint Surg Br. 2002;84(1):1-8.
4. Wheeler PC, Keating JF. Management of Achilles tendinopathy. Curr Orthop. 2005;19(2):113-122.
5. Paavola M, Kannus P, Järvinen M, Khan K, Józsa L, Järvinen TLN. Achilles tendinopathy. J Bone Joint Surg Am. 2002;84(11):2062-2076.
6. Hawkins RJ, Kopta JA. Surgical treatment of Achilles tendinitis. Clin Orthop Relat Res. 1978;132:132-139.
7. Martin RL, Chimenti R, Cuddeford T, Houck J, Johnson J, Matheson J, et al. Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Clinical Practice Guidelines. J Orthop Sports Phys Ther. 2021;51(11):CPG1-CPG47.
8. Maffulli N, Longo UG, Denaro V. Novel approaches for the management of tendinopathy. J Bone Joint Surg Am. 2010;92(15):2604-2613.