What UK clinicians get wrong about Achilles tendinopathy

Achilles tendinopathy is the kind of thing that gets two minutes in a 4th-year MSK lecture and then never really comes up again until a runner is sitting in front of you, eight months in, frustrated, asking whether they need an MRI. The condition is common, the evidence is good, the management is unglamorous, and the gap between best practice and what actually happens in UK clinics is wider than it should be.

I see the same five mistakes nearly every week. Most of them are made by experienced clinicians who would push back hard if you suggested they were getting it wrong. None of them are dramatic. They are the kind of small, ingrained habits that nobody calls you on because the patient eventually gets better anyway, just slower than they should have.

Here is the honest version, in the order they cost the most.

Mistake 1: Calling everything tendonitis

The terminology problem is older than I am. We are still calling these presentations "Achilles tendonitis" in clinic letters, in patient information leaflets, and on referral forms. The pathology is not inflammatory in the classical sense. There are some inflammatory mediators in the early phase, but the dominant process is failed healing of a non-inflammatory tendon: collagen disorganisation, neovascularisation, and a loss of the normal fibre architecture.

This is not a pedantic point. The label drives the management. If a patient is told they have tendonitis, they reasonably expect anti-inflammatories to do the heavy lifting. NSAIDs become the first-line plan. Rest is prescribed. The tendon then sits there, deconditioned, while the underlying load-tolerance problem goes untouched.

The fix is small and free. Use "tendinopathy". Explain in plain language: "This is wear and underloading, not a fire we need to put out. The tendon needs the right kind of work, not rest." Patients accept this readily once you tell them; it is the clinical letter culture that is slow to shift.

Mistake 2: Stopping load too soon, then starting it too gently

The second mistake is the inverse of the first. Once a clinician has accepted that loading is the treatment, the next failure mode is pulling the patient off load entirely at the first flare, then restarting at intensities that are too low to drive any adaptation.

The Alfredson protocol, eccentric loading, heavy slow resistance, isometrics in irritable phases - all of these have decent evidence. What they have in common is that they are loading protocols. They work because the tendon adapts to the stimulus. If you halve the volume the moment the patient reports a four out of ten, you have undone the stimulus.

The pain-monitoring framework most groups use is "up to a 5/10 during the exercise, settling within 24 hours, no morning-after worsening". That is the working definition of a tolerable session. Patients can be coached through this. They are not being asked to grit their teeth through agony. They are being asked to accept that some symptoms during loading are part of the treatment, not a sign that the treatment is hurting them.

If you are going to send a patient away with a tendon-loading programme, you have to give them this framework explicitly. Otherwise the next reasonable-sounding twinge will reset them to zero.

Mistake 3: Underusing isometrics in the irritable phase

Isometrics get under-prescribed in primary care. The usual story is that the patient comes in flaring, the clinician backs off all loading, the tendon deconditions further, and the patient returns six weeks later worse than before.

When to reach for isometrics

Isometrics are useful precisely when the tendon is too irritable for full eccentric or heavy slow resistance work. A reasonable starting point is five sets of 45 seconds of holding a single-leg calf raise just off the floor, performed at around 70% of perceived maximum effort, with two minutes of rest between sets, two to three times per week. The hold is sustained, the position is short of end-range, and the load is high enough to matter but low enough that pain stays in the manageable band.

The mechanism is not fully understood. Some of the analgesic effect is probably central. Some of it is mechanical: a sustained contraction modulates how the tendon transmits load and may dampen the nociceptive signal. The clinical point is more useful than the mechanism. Isometrics give you a way to keep loading the tendon when the patient cannot tolerate the dynamic protocols. That preserves the gains and bridges the gap to heavier work.

This is one of the highest-yield changes a generalist can make.

Mistake 4: Imaging too early, or at all

Most cases of Achilles tendinopathy do not need imaging. The diagnosis is clinical. The history (gradual onset, morning stiffness, the warm-up phenomenon, pain with high-load activities) and the examination (palpable thickening, focal tenderness, pain with single-leg heel raise) get you there in the vast majority of presentations.

Ultrasound is reasonable in three scenarios. First, when the diagnosis is genuinely uncertain - the pain is atypical or the location does not fit. Second, when you suspect a partial tear in someone with a sudden increase in pain or a palpable defect. Third, when imaging findings would actually change management, which is a smaller set of cases than people imagine.

MRI in primary care is almost never the right first investigation for tendinopathy. It is sensitive but it is also sensitive to incidental findings that do not correlate with symptoms. Ordering MRI early in the pathway tends to surface findings that complicate rather than clarify the management plan. A patient who has been told they have "extensive tendinosis with paratenon thickening" on MRI is harder to coach into a loading programme than a patient who has been told the diagnosis is clinical and the treatment is consistent work over months.

If you are going to image, image with a clinical question. "Does this patient have a partial tear that would change my plan?" is a clinical question. "Let us see what the tendon looks like" is not.

Mistake 5: Forgetting the calf-soleus distinction

The Achilles is loaded by two different muscles, gastrocnemius and soleus. Gastrocnemius crosses both the knee and the ankle; soleus crosses only the ankle. That anatomical detail has a direct rehabilitation implication that gets skipped.

Bent-knee versus straight-knee loading

If you load the tendon with the knee straight (a standing calf raise, an eccentric heel drop off a step), you are loading both gastrocnemius and soleus. If you load it with the knee bent to around 90 degrees (a seated calf raise), you are loading soleus preferentially because gastrocnemius is shortened and contributes much less force.

A loading programme that only uses straight-knee work systematically under-loads soleus. Soleus is the slow-twitch, endurance-dominated workhorse of the calf complex. In runners and middle-distance athletes it carries an enormous proportion of the load. Skipping it is one of the reasons patients can complete a textbook eccentric programme and still struggle when they return to running.

The fix is simple. Build both into the programme from the start. Equal volume of bent-knee and straight-knee work, scaled to the patient's tolerance. The Silbernagel protocol does this well. So does heavy slow resistance done with both knee positions.

What good looks like

A patient with Achilles tendinopathy walks out of a good first appointment with four things. A clear name for the condition that does not include the word tendonitis. A plan that involves loading rather than rest. A pain-monitoring framework so they know what to expect. And a programme that includes both bent-knee and straight-knee calf work, with isometrics on standby for irritable phases.

Imaging is not requested unless there is a clinical question. Anti-inflammatories are not the first or only intervention. The patient is told that this will take three to six months of consistent work and that progress is non-linear. They are given permission to load through tolerable symptoms.

That is the whole intervention. None of it is novel. None of it requires a referral. Most of it can be delivered in twenty minutes by a thoughtful GP or physiotherapist with a printed sheet. The reason it does not happen consistently in the UK is not a knowledge gap at the top of the field. It is a translation gap between the evidence and the everyday clinical encounter, and that gap is what most of the patients I see are stuck inside.

If you want to read more, the Achilles Tendinopathy topic page has the full structured walk-through, including the protocols, evidence summary, and red flags for rupture.