Achilles Tendinopathy

Achilles tendinopathy is a load related degenerative tendon disorder with pain, focal thickening and reduced loading capacity. It is classed as midportion (2 to 6 cm proximal to the calcaneal insertion, the more common form) or insertional (at the enthesis, often with a Haglund deformity or retrocalcaneal bursitis). The lifetime risk in recreational runners is 7 to 9%, and peak onset is 30 to 50 years.

The tendon shows disordered collagen, increased ground substance, cell proliferation and neovascularization, with little inflammatory infiltrate. Risk factors:

• Training errors (sudden increase in load, hills, speed work)
• Obesity, diabetes, hypercholesterolemia (bilateral disease and xanthomas suggest familial hypercholesterolemia)
• Fluoroquinolone and corticosteroid exposure
• Spondyloarthritis (insertional disease)
• Pes cavus or pes planus

Most patients improve with loading therapy over 3 to 6 months, but 25% have symptoms at 5 years. The main complication is partial or complete rupture.

• Morning stiffness settling within minutes, pain at the start of exercise that warms up and returns afterwards
• Tendon thickening, a tender nodule, and an arc sign (the swelling moves with ankle dorsiflexion and plantarflexion)
• Insertional disease: pain at the heel, worse on dorsiflexion and stairs, a palpable bony prominence
• Calf weakness and a reduced single leg heel raise count
• Thompson squeeze test is normal
• Red flags: a sudden pop with loss of push off (rupture), recent fluoroquinolone, bilateral involvement with xanthomas, warm swelling with fever

• Clinical diagnosis by history and palpation.
• Ultrasound (first imaging test): fusiform thickening with anteroposterior diameter over 6 mm, hypoechoic areas, loss of fibrillar pattern and neovascularity on Doppler, with calcification and retrocalcaneal bursitis in insertional disease.
• MRI for intratendinous tears, bone marrow edema and when the diagnosis is uncertain.
• Lateral radiograph for insertional calcification, a Haglund deformity (Fowler-Philip angle over 75 degrees, or a positive parallel pitch line).
• Fasting lipids, HbA1c and inflammatory markers when disease is bilateral or atypical.

Differentials: partial rupture, retrocalcaneal bursitis, plantaris tendon involvement, sural neuritis, posterior ankle impingement, calcaneal stress fracture, Sever disease in a child.

• Load management: relative rest from provocative activity while maintaining aerobic fitness, with a cycle or swim substitute.
• Midportion loading program for 12 weeks: eccentric heel drops, 3 sets of 15 repetitions twice daily with the knee straight and again with the knee bent, using a step and progressing load with a backpack. Alternatively heavy slow resistance training, 3 sets of 15, 12, 10 and 8 repetitions three times a week, at 4 to 6 seconds per repetition.
• Insertional disease: the same loading without lowering the heel below neutral, with a 12 mm heel raise in the shoe for 4 to 6 weeks.
• Analgesia: paracetamol 1 g orally every 6 hours (maximum 4 g/day), or ibuprofen 400 mg orally every 8 hours with food for up to 7 days. NSAIDs relieve pain but do not alter healing.
• Extracorporeal shockwave therapy: 3 weekly sessions of 2000 pulses at 0.12 to 0.20 mJ/mm2 for refractory disease.
• Topical glyceryl trinitrate: one quarter of a 5 mg/24 h patch (1.25 mg) applied over the tendon each day for 12 weeks. It may cause headache.
• Avoid corticosteroid injection (rupture risk). Stop fluoroquinolones.
• Surgery after 6 months of failed treatment: debridement of degenerate tendon with plantaris release for midportion disease, and calcaneal exostectomy with detachment and reattachment by anchors for insertional disease. Transfer flexor hallucis longus when over 50% of the tendon is excised. Cefazolin 2 g IV before incision.
• Complications of surgery: wound breakdown, sural nerve injury, infection.

Follow up every 6 weeks. Counsel on a return to running at the 12 week mark if pain is under 3 out of 10, and on weight and lipid control.