Achilles Tendinopathy

Location is the primary classification and the one that is clinically most useful.

Approximately 20-25% of cases have combined insertional and non-insertional disease.

Cook and Purdam's continuum model (2009) stages the tendon by how far the matrix has broken down.

The model emphasises that this is a spectrum of disease and that the early stages are reversible.

The Astrom classification grades the MRI appearance.

MRI grade correlates with treatment outcomes and surgical findings.

What it shows. The tendinopathic tendon is thickened, with an AP diameter greater than 6mm abnormal, and the following are the findings to look for:

• Hypoechoic areas, the degenerative regions
• Loss of the normal fibrillar pattern
• Neovascularisation on Power Doppler
• Paratenon thickening in paratendinopathy

Why it comes first. It is dynamic, allows comparison with the other side, is cost-effective, guides injections, and Power Doppler assesses neovascularisation. The findings correlate well with symptoms and can guide treatment aimed at areas of neovascularisation, although whether such treatment helps is contested (see Controversies).

What it shows. On T1 the tendon is thickened with normal or slightly increased signal; on T2 and STIR the signal within the tendon substance is increased. Mid-portion disease is a fusiform thickening, insertional disease shows spurring and retrocalcaneal bursitis, and a partial tear is high T2 signal with a partial-thickness defect.

Why it is the gold standard. Superior soft-tissue contrast, accurate detection of partial tears, assessment of the bone (Haglund, calcaneal oedema) and preoperative planning. Against it are cost, static imaging only, and that it may overestimate pathology; it remains valuable for comprehensive preoperative assessment.

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The insertion. Radiographs have limited value in mid-portion tendinopathy and earn their place in insertional disease, where they show a Haglund deformity, insertional calcification and retrocalcaneal spurring. Parallel pitch lines assess the Haglund prominence: lines drawn parallel to the sole through the highest point of the posterior calcaneal tuberosity should not project into the retrocalcaneal bursa.

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The Alfredson protocol, for mid-portion disease. Heavy-load eccentric calf training is the historical first-line treatment, and the dose is specific:

• 3 sets of 15 repetitions, the original Alfredson protocol
• Twice daily, morning and evening, 7 days a week
• 12 weeks minimum
• Straight knee (gastrocnemius) and bent knee (soleus)
• Performed off the edge of a step, so the heel drops below the level of the forefoot into dorsiflexion
• Rise on the good leg, lower on the affected leg: the eccentric phase only
• Progress through moderate discomfort (pain 4-5/10), adding load with a backpack or weights as pain decreases

That works out at 180 repetitions a day, every day, for three months, which is why adherence is the commonest reason it "fails".

Insertional disease needs a different protocol, not a watered-down version of this one. The step is the problem. Dropping the heel below the forefoot takes the ankle into dorsiflexion, and dorsiflexion beyond neutral compresses the tendon against the superior calcaneal tuberosity. At the mid-portion that compression is irrelevant; at the insertion it is the mechanism of the disease, so a full-range eccentric programme loads the tendon exactly where it is already being pinched. This is why a patient with insertional disease frequently returns worse after standard physiotherapy, as in the second viva scenario below, and it is a mechanism worth being able to explain rather than simply asserting that "eccentrics do not work at the insertion".

The floor-level (Jonsson) protocol is the insertional equivalent.

• The same dose: 3 sets of 15 repetitions, twice daily, for 12 weeks
• Performed standing on the floor, not on a step, so the heel descends only to the level of the floor and the ankle never passes beyond neutral into dorsiflexion
• Load added by backpack as symptoms allow, exactly as in the mid-portion protocol
• Roughly two-thirds of patients report satisfaction with this modification, against much lower satisfaction when full-range loading is used at the insertion

Heavy slow resistance is the alternative for mid-portion disease. Named in most guidelines as an equal alternative, but only useful if you can state the dose, because its entire practical advantage is the time commitment:

• Three sessions per week, not twice daily, for 12 weeks: about 36 sessions against roughly 168 for Alfredson
• Both concentric and eccentric phases, performed slowly, about 3 seconds up and 3 seconds down
• Progressive external loading, from around a 15-repetition maximum in the first weeks to a 6-repetition maximum by the end
• Heel raises seated (soleus) and standing, plus leg press

In a randomised trial the two produced equivalent VISA-A improvement at 12 weeks and 52 weeks, with better compliance for HSR (92% versus 78%). Choose by what the patient will actually do.

Adjuncts. These sit alongside the loading programme, and the first three follow from the same mechanical logic as the floor-level protocol:

• Heel lifts reduce strain on the tendon and, in insertional disease, hold the ankle out of dorsiflexion all day
• Open-backed footwear or a soft heel counter, to stop the shoe pressing on the insertion
• ESWT, 3 sessions of 2000 impulses; in a systematic review of insertional disease it outperformed both eccentric training and a wait-and-see policy
• GTN patches (nitroglycerin), which may improve collagen synthesis
• Activity modification, reducing provocative activities temporarily
• Orthotics if foot posture is abnormal

What not to do. Complete rest deloads the tendon and is harmful, and aggressive stretching is avoided acutely.

Indications.

• Failed conservative treatment of 6 months or more, including a compliant eccentric programme
• Unable to return to the desired activity level
• Progressive symptoms despite treatment

What tips the balance. Bilateral disease is more likely to need surgery. Radiographic changes (calcification, a Haglund deformity) and extensive tendinosis on MRI also count as indications, and elite athlete needs put the patient on an expedited treatment pathway.

Which operation. For mid-portion disease the operation is open debridement through a medial or posterior midline approach, with paratenon stripping and longitudinal tenotomies, an FHL transfer if more than 50% of the tendon has to be debrided, and a gastrocnemius recession if there is an equinus contracture. For insertional disease it is a central tendon-splitting approach with debridement of the insertional calcification, Haglund resection, retrocalcaneal bursectomy and suture-anchor repair of the detached tendon; FHL transfer is less commonly needed. Good or excellent outcomes follow in 75-85%.

Approach. Prone, with a tourniquet at the thigh, through a medial or posterior midline incision. The medial approach is preferred because it keeps the incision away from the sural nerve, which lies laterally.

If a gastrocnemius recession is needed, perform it through the same or a separate incision at the musculotendinous junction.

Why FHL. It is indicated when more than 50% of the tendon requires debridement, and it is the donor of choice because it is in phase with the Achilles as a plantarflexor, has a similar muscle fibre type, offers excellent tendon quality and length, brings a new blood supply, and costs the patient little at the donor site.

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The central tendon-splitting approach.

• J-shaped or inverted U incision over the insertion
• Split the tendon longitudinally in the midline
• Debride the degenerative tissue and calcification
• Resect the Haglund prominence if present
• Excise the retrocalcaneal bursa
• Reattach the tendon with suture anchors

If more than 50% of the insertion has been detached, use 2-3 suture anchors for the reattachment, and consider an FHL transfer for significant detachment.

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Indication. An isolated gastrocnemius contracture, with a positive Silfverskiold test. It may be combined with Achilles debridement for comprehensive treatment of equinus-related tendinopathy.

The Strayer procedure.

• Medial or posterior incision at the musculotendinous junction
• Identify the gastrocnemius aponeurosis
• Divide the aponeurosis transversely
• Allow the gastrocnemius to slide distally
• Do not repair; allow healing in the lengthened position

The Baumann procedure releases the gastrocnemius proximally at the muscle origin, with less cosmetic scarring and similar outcomes.

Loading programmes. A transient increase in pain is expected and the programme continues through it. Calf muscle soreness occurs, and rarely a partial rupture where the tendon was already weakened. Non-operative complications are generally minor and self-limiting.

Failure. Conservative treatment fails in 10-30% of mid-portion cases and 40-50% of insertional cases, and these may require eventual surgery.

Early.

• Wound healing problems (5-10%), higher in insertional surgery because of the location
• Sural nerve injury with a lateral approach
• Deep vein thrombosis
• Infection (1-2%)

Late.

• Tendon rupture, rare and typically early postoperative
• Persistent pain (10-20%)
• Weakness, usually mild and temporary
• Adhesions and stiffness
• Recurrence of symptoms

FHL transfer.

• Toe flexion weakness, minimal and usually not noticeable to patients
• Neurovascular injury during harvest
• Transfer failure (rare)

Insertional surgery.

• Avascular necrosis of the calcaneal tuberosity (rare)
• Re-detachment requiring revision

The overall surgical complication rate is approximately 10-15%.

After a simple debridement (less than 50% of the tendon), rehabilitation moves through four phases; earlier rehabilitation gives better outcomes than prolonged immobilisation.

A tendon transfer needs a longer protection period, slower progression of loading, more attention to toe flexion exercises and a later return to sport; it adds approximately 6-8 weeks to the overall recovery.

• Weeks 0-6: boot with heel wedges, progressive weight bearing
• Weeks 6-12: wean the boot, begin physiotherapy
• Week 8: start eccentric exercises
• Week 12: begin running progression
• Months 6-9: return to full activity

Insertional surgery requires longer protection to allow bone-tendon healing at the suture anchor sites, so the progression is slower again.

• Weeks 0-4: non-weight bearing in a splint or cast
• Weeks 4-8: weight bearing in a boot
• Weeks 8-12: wean the boot, physiotherapy
• Week 12: begin eccentric exercises
• Months 4-6: running progression
• Months 6-9: full activity