Achilles Tendinitis

Pain and thickening of the Achilles tendon from overuse. The correct term is Achilles tendinopathy, since the process is degenerative (disorganised collagen, increased ground substance and neovascularisation) with little true inflammation. Pure inflammatory peritendinitis (paratenonitis) occurs early.

Two forms:

• Midportion tendinopathy (about 55 to 65%): 2 to 6 cm proximal to the calcaneal insertion, in an area of relatively poor blood supply.

• Insertional tendinopathy (about 20 to 25%): at the enthesis on the posterior calcaneus, often with a bony spur, calcification and retrocalcaneal bursitis.

Incidence is about 2 to 3 per 1000 adults per year. It affects 6 to 18% of recreational runners over a lifetime, with a peak at 30 to 50 years, and is common in jumping and racket sports.

Risk factors: sudden increase in training volume or intensity, hill and speed work, hard surfaces, poor or worn footwear, tight calf, foot pronation, obesity, diabetes, hypertension, hyperlipidaemia (including familial hypercholesterolaemia with xanthomas), inflammatory arthritis (spondyloarthritis, psoriatic arthritis), and drugs (fluoroquinolones, systemic corticosteroids, statins, aromatase inhibitors).

It can progress to partial tear or complete rupture, especially after steroid injection or fluoroquinolone use.

• Pain and stiffness in the Achilles region, worst in the morning and at the start of activity, easing with warm up and returning after exercise. In advanced disease, pain occurs during activity, with walking, stairs, and at rest.

• Examination: a tender, thickened, fusiform nodule in the midportion (that moves with ankle dorsiflexion and plantarflexion), a painful arc sign (the swelling moves with the tendon), crepitus in peritendinitis, tenderness at the insertion in insertional disease, and pain on single leg heel raise or hopping. Calf tightness and weakness of heel raise may be present.

Differential diagnosis: partial Achilles tear, complete rupture (palpable gap, absent plantarflexion on calf squeeze), retrocalcaneal bursitis, plantaris tendon involvement, posterior ankle impingement, os trigonum syndrome, calcaneal stress fracture, Sever disease (children), sural nerve entrapment, posterior tibial or peroneal tendinopathy, deep vein thrombosis, calf strain, spondyloarthritis enthesitis, gout, and xanthoma.

Red flags: sudden pop with inability to push off (rupture), warmth and swelling with fever, calf swelling, systemic inflammatory features, and recent fluoroquinolone or steroid use.

Complications: chronic pain, partial tear, rupture, loss of function and sport, and secondary calf weakness.

• Clinical. Check the calf squeeze test (Achilles continuity) in all patients, and examine foot alignment, calf flexibility and footwear.
• Ultrasound shows tendon thickening, hypoechoic areas, neovascularity on Doppler, partial tears, calcification and peritendinous fluid. MRI shows intratendinous signal change, tears and bone marrow oedema, and is used for uncertain diagnosis, suspected partial tear and before surgery.
• X-ray of the heel and ankle (lateral view) shows insertional calcification, spur and a posterosuperior calcaneal prominence, and excludes stress fracture.
• Blood tests: lipid profile, HbA1c, urate, CRP, ESR, and HLA-B27 or other markers when systemic disease is suspected.

• Load management and education: reduce, but do not stop, provocative loads (running, jumping, hills) so that pain stays at 4 out of 10 or less during activity and settles within 24 hours. Complete rest weakens the tendon.
• Analgesia: paracetamol 1 g orally 6 hourly. Topical diclofenac 1% gel 2 to 4 g 3 to 4 times daily. Short course oral NSAIDs (ibuprofen 400 mg 8 hourly with food for 5 to 7 days) may help acute peritendinitis but do not alter tendinopathy. Ice after activity.
• Exercise therapy (first line, best evidence), 12 weeks or longer:
  • Isometric holds for pain relief early: heel raise or leg press holds, 5 repetitions of 45 seconds at about 70% effort, once or twice daily.
  • Eccentric heel drops (midportion): 3 sets of 15, with the knee straight and then bent, twice daily, 7 days a week for 12 weeks, from a step and with added load as pain allows. Pain up to 5 out of 10 is acceptable if it settles within 24 hours.
  • Insertional disease: perform heel drops on flat ground (do not let the heel drop lower than the step edge), because dorsiflexion compresses the insertion.
  • Heavy slow resistance (seated and standing calf raises, 3 to 4 sets of 6 to 15 repetitions, 3 times weekly), then plyometrics and return to running with graded progression.
• Footwear and orthoses: a heel lift of 10 to 12 mm in both shoes for 4 to 6 weeks to reduce tendon strain (not as a long term measure), cushioned shoes, orthoses for pronation, and avoidance of hard flat shoes.
• Adjuncts for persistent disease (evidence mixed or limited): extracorporeal shock wave therapy (3 to 5 weekly sessions, more effective in insertional disease), glyceryl trinitrate patch (a quarter of a 5 mg per 24 hour patch, about 1.25 mg per 24 hours, applied over the tender area and changed daily for 12 weeks, with headache as the main side effect), platelet rich plasma (a single 3 to 5 mL ultrasound guided injection, with uncertain benefit), high volume image guided injection, and sclerosing injection of neovessels.
• Do not inject corticosteroid into or around the Achilles tendon, because of a high risk of rupture.
• Stop or substitute fluoroquinolones and review statin and steroid exposure when tendon pain begins.
• Surgery after at least 6 months of correct conservative treatment: percutaneous tenotomy or tendon debridement with or without excision of the plantaris, for midportion disease (about 70 to 85% success). For insertional disease: debridement of the insertion, excision of the posterosuperior calcaneal prominence and bursa, and reattachment with suture anchors, with flexor hallucis longus transfer for extensive degeneration (rehabilitation 4 to 6 months).
• Complete rupture: urgent orthopaedic review for functional bracing or surgical repair, with equinus immobilisation and early weight bearing.
• Systemic disease: treat hypercholesterolaemia (atorvastatin 40 to 80 mg daily, with dietary measures), control diabetes, and manage spondyloarthritis with NSAIDs and biologic therapy under rheumatology.
• Prevention: gradual progression of training load (no more than about 10% per week), calf strengthening, suitable shoes, and avoiding sudden hill or speed sessions.
• Special groups:
  • Elderly: exercise at lower load, avoid fluoroquinolones, and check for rupture risk.
  • Pregnancy: heel lifts, physiotherapy and paracetamol. Avoid NSAIDs after 20 weeks.
  • Diabetes and obesity: optimise glucose, and weight loss improves outcome.
  • Renal impairment and gastrointestinal disease: avoid oral NSAIDs.
• Follow up: review at 6 weeks and 3 months. Refer to sports medicine, orthopaedics or rheumatology for no improvement by 3 to 6 months, suspected tear or rupture, or consideration of procedures.