A ruptured Achilles tendon typically shows a visible gap or indentation at the back of the ankle, about 2 to 3 inches above the heel bone, along with noticeable swelling and bruising. Most people also experience a distinct “pop” at the moment of injury and an immediate inability to push off the injured foot. Here’s what to look for and how to tell a full rupture from a partial tear.
The Gap You Can See and Feel
The most telling visual sign of a complete Achilles rupture is a divot or depression at the back of the lower leg. The Achilles tendon normally forms a firm, cord-like ridge running from the calf down to the heel. When it ruptures, that ridge disappears at the injury site, and you can often see a dip in the skin where the torn ends have pulled apart. Doctors describe being able to run a finger along the back of the ankle and feel this defect directly.
This gap forms because the two ends of the severed tendon retract away from each other. Imaging studies show that the space between the torn ends can measure over 2 centimeters, roughly the width of a thumb. The rupture almost always happens about 4 to 5 centimeters above where the tendon attaches to the heel bone. This spot has a relatively poor blood supply, which makes it the weakest link in the chain.
Within minutes to hours, the area swells significantly and often bruises. The swelling can partially fill in the gap, making it harder to see as time passes. That’s why the divot is most obvious immediately after the injury, before fluid accumulates.
What It Feels Like in the Moment
Most people hear a loud pop or snap at the instant the tendon tears. The sensation is startling: it feels as if someone kicked or punched you hard in the back of the leg, even though nobody is behind you. Many people actually turn around to look.
Pain varies. Some people experience sharp, intense pain right away, while others describe it as surprisingly mild considering the severity of the injury. What’s consistent is what happens next: you lose the ability to push off with that foot. Walking becomes a flat-footed shuffle. Rising onto your toes on the injured side is either extremely difficult or completely impossible, and this functional loss is one of the clearest signs that the tendon has fully torn rather than just been strained.
How a Full Rupture Differs From a Partial Tear
A partial tear and a complete rupture can both cause pain and swelling at the back of the ankle, but they look and feel different in important ways. With a partial tear, some tendon fibers remain intact. You’ll have pain and weakness, but you can usually still point your toes downward with reduced strength. There’s no palpable gap because the remaining fibers bridge the injury site.
A complete rupture severs all fibers. The gap is detectable by touch, the foot hangs noticeably flatter than the uninjured side, and pushing off the ground feels like stepping into nothing. On imaging, a partial tear shows disrupted fibers mixed with intact ones, while a full tear shows a fluid-filled space with both ends of the tendon pulled apart.
It’s also worth knowing what a rupture is not. Achilles tendinitis, the chronic overuse condition, causes a different pattern entirely: stiffness with the first steps of the morning, tenderness that gradually warms up with activity, and a thickened but intact tendon. There’s no pop, no sudden inability to walk, and no gap.
The Resting Foot Position Test
One of the simplest ways to spot a ruptured Achilles at home is to compare how your feet hang at rest. Lie on your stomach with your knees bent to about 90 degrees and let your feet relax. A healthy Achilles tendon holds the foot in a slight downward point, like a ballerina’s foot in miniature. If the tendon is ruptured, that foot will hang flat or nearly neutral, clearly different from the other side. The contrast between the two feet can be striking and is one of the first things a doctor looks for.
How Doctors Confirm the Rupture
The standard bedside test is called the Thompson test. You lie face down on an exam table with your feet hanging over the edge. The examiner squeezes your calf muscle firmly. In a healthy leg, this squeeze pulls on the intact tendon and causes the foot to point downward. If the foot doesn’t move at all, the tendon is ruptured. It’s a quick, reliable test that often confirms the diagnosis without any imaging.
When imaging is needed, ultrasound can show the tear in real time. The torn fibers appear as a dark gap between the retracted tendon ends, sometimes with a blood clot filling the space. Doctors can even move the ankle during the scan to watch the gap open and close: in one documented case, a 2.3-centimeter gap shrank to 1.7 centimeters when the foot was pointed downward. Fat from the surrounding tissue can also herniate into the gap, which is another hallmark of a complete tear on ultrasound.
MRI provides the most detailed picture. A full rupture appears as a bright, fluid-filled gap on certain sequences, with the tendon ends either retracted apart or crumpled and overlapping. Partial tears show a more mixed signal, with some fibers still bridging the injury. MRI is particularly useful when the clinical picture is unclear or when a surgeon needs to plan a repair and wants to know exactly how far apart the tendon ends have separated.
What the Injury Looks Like Over Time
In the first few hours, the back of the ankle swells rapidly. Bruising often develops within a day or two and can spread down toward the heel and sole of the foot, sometimes extending up the calf. The skin may appear tight and shiny from the swelling. The visible gap becomes harder to identify as swelling fills the space, which is one reason why some people delay seeking care, mistaking the injury for a bad sprain.
The key difference between a severe ankle sprain and a ruptured Achilles is location and function. Sprain swelling concentrates around the ankle bones on the sides of the foot. Achilles rupture swelling sits higher, along the back of the leg above the heel. And while a sprained ankle still lets you point your toes, a ruptured Achilles does not. If you can’t rise onto your toes and you felt a pop in the back of your leg, that combination points strongly toward a rupture regardless of what the swelling looks like on the surface.