If you’re feeling pain at the back of your ankle or heel, the most telling clue is how it started. A sudden, sharp pain during activity, especially with an audible pop or snap, points toward a tear or rupture. Pain that crept in gradually over days or weeks, particularly stiffness with your first steps in the morning, is more consistent with tendonitis from overuse. Either way, the location and behavior of the pain can help you figure out what’s going on before you see a doctor.
Sudden Injury vs. Gradual Onset
The single most important question is whether you can trace the pain back to a specific moment. An Achilles rupture is what’s called a “step-off” injury: it happens when your foot springs off the ground to propel you forward, like pushing off for a sprint, jumping, or lunging. Many people hear or feel a pop or snap at the back of the ankle, followed immediately by swelling and difficulty walking. Some describe it as feeling like they were kicked in the heel, even though nobody touched them.
Tendonitis works differently. It builds over time from repetitive stress, and there’s no single moment you can point to. You might first notice it as mild stiffness or achiness after a run, then realize it’s getting worse week after week. Morning stiffness that loosens up after a few minutes of walking is one of the classic early signs.
Where Exactly the Pain Is
Pain location narrows things down further. There are two common spots for Achilles problems:
- Mid-tendon (a few inches above the heel): This is noninsertional tendonitis, where the fibers in the middle of the tendon start to break down, swell, and thicken. You may feel a tender lump or notice the area looks slightly swollen compared to your other leg.
- At the heel bone: This is insertional tendonitis, affecting the point where the tendon attaches to the base of the heel. Pain here can overlap with other heel conditions, and it sometimes comes with a bony bump at the back of the heel.
A rupture typically causes pain and swelling higher up, in the back of the ankle, and you may be able to feel a gap or indentation in the tendon if the tear is complete.
What You Can and Can’t Do
Try these simple functional checks to gauge severity:
- Standing on tiptoes: If you can’t rise onto the ball of your injured foot, or it feels dramatically weaker than the other side, that suggests a significant tear rather than mild inflammation.
- Walking normally: A ruptured Achilles eliminates your push-off power. You’ll notice you can’t spring forward off that foot the way you normally would, and your gait will feel flat or shuffling on the injured side.
- Pointing your foot downward: With a complete rupture, actively pushing your foot down (like pressing a gas pedal) is extremely weak or impossible, even though some motion may remain from other muscles in the foot.
With tendonitis, you can usually still do all of these things, just with pain. That pain-but-functional distinction is one of the clearest differences between inflammation and a tear.
The Squeeze Test
Doctors use a simple hands-on check called the Thompson test to screen for a complete rupture. You can have someone help you try a version at home. Lie face down on a bed with your feet hanging over the edge. Have someone firmly squeeze the widest part of your calf muscle. If your Achilles tendon is intact, your foot will automatically point downward when the calf is squeezed. If nothing happens and the foot stays still, that’s a strong signal the tendon is torn.
This test is most reliable for complete ruptures. It’s less sensitive for partial tears, so a normal result doesn’t entirely rule out damage. But if your foot doesn’t move at all during the squeeze, you should get medical evaluation promptly.
Grades of Achilles Tears
Not every tear is all-or-nothing. Achilles injuries are classified into three grades:
- Grade 1: A mild partial tear with minimal fiber damage. Pain and swelling are present, but you retain most of your strength and mobility.
- Grade 2: Less than half of the tendon fibers are torn. Pain is more significant, and weakness becomes noticeable during activities like climbing stairs or pushing off while walking.
- Grade 3: A full rupture where most or all fibers are torn. This typically causes immediate, severe pain, an inability to bear weight normally, and visible swelling.
You can’t reliably distinguish between these grades without imaging, but the pattern of your symptoms gives a reasonable first estimate. If you have pain but can still function, you’re more likely in Grade 1 territory. If you felt a pop and can’t push off your foot, Grade 3 is the concern.
What to Do in the First 48 Hours
Regardless of whether you suspect tendonitis or a tear, the initial approach is the same. Apply ice several times a day for 20 minutes at a time, with at least an hour off between sessions, for the first 48 to 72 hours. Keep the injured leg elevated above the level of your heart when you’re resting to limit swelling. Avoid putting full weight on the leg if walking is painful, and use a compression bandage if swelling is significant.
What you should not do is push through the pain. Unlike some muscle soreness that benefits from gentle movement, continuing to load a damaged Achilles tendon risks turning a partial tear into a complete one.
How Doctors Confirm the Diagnosis
If your symptoms suggest more than mild tendonitis, imaging helps pin down the diagnosis. Ultrasound is typically the first-line tool because it’s quick, widely available, and cost-effective. It gives a good look at tendon fiber integrity and can identify thickening, partial tears, and complete ruptures. For midportion tendon problems, ultrasound has a diagnostic accuracy around 87%, which is comparable to MRI.
MRI becomes more useful when the injury is near the heel bone (insertional), when a partial rupture is suspected, or when the picture is unclear. MRI picks up bone bruises, bursitis, and other surrounding damage that ultrasound can miss, reaching about 95% accuracy for insertional problems. Your doctor will typically start with ultrasound and order an MRI only if more detail is needed.
Recovery Expectations
How long you’re dealing with this depends heavily on what’s actually injured. Mild tendonitis often improves within a few weeks with rest, ice, and gradual return to activity. More stubborn cases can take two to three months, especially if you’ve been ignoring the pain and training through it.
A complete rupture is a longer road. Whether treated with surgery or managed with bracing and rehabilitation, full healing typically takes four to six months. Even after recovery, research shows calf muscle strength on the injured side can remain 10% to 30% lower than the uninjured side for up to two years. Long-term gait studies reveal that people who’ve had a rupture generate less push-off force when walking, with measurably reduced foot motion at toe-off. These deficits can be minimized with dedicated rehabilitation, but they’re worth knowing about so you commit fully to your recovery exercises.
Risk Factors Worth Knowing
Some people are more vulnerable to Achilles injuries than others. Weekend warriors who ramp up activity suddenly after periods of inactivity are a classic profile. Age plays a role too, as tendons lose elasticity over time. One risk factor that surprises many people: fluoroquinolone antibiotics, a commonly prescribed class that includes ciprofloxacin and levofloxacin, are associated with increased risk of Achilles tendon rupture. If you’ve recently taken one of these antibiotics and are now experiencing Achilles pain, mention it to your doctor.