Why Does My Medial Malleolus Hurt? Causes and Treatments

Pain at the bony bump on the inside of your ankle, the medial malleolus, can stem from at least half a dozen different structures crammed into a remarkably small space. The bone itself can fracture or develop a stress reaction. Tendons running behind it can become inflamed or torn. The broad ligament anchored to it can be sprained. A nerve passing just beneath it can get pinched. Even gout crystals can settle into the nearby joint. Figuring out which structure is responsible matters, because the treatments are quite different from one cause to the next.

Why This Spot Is So Vulnerable

The medial malleolus is the knob of bone at the bottom inner edge of your shinbone (tibia). It is not just a bump; it is a critical anchor point. The deltoid ligament, a strong fan-shaped band that prevents your ankle from rolling inward, attaches here. That ligament has multiple components originating from different parts of the malleolus, some from its front surface and some from its back surface and the groove between them.¹ Behind the bone, the posterior tibial tendon and several other tendons curve around it on their way into the foot. And just beneath the surface, the posterior tibial nerve passes through a narrow channel called the tarsal tunnel. All of these structures share the same tight corridor, so swelling or damage to any one of them can produce pain that feels like it is coming from the bone itself.

Stress Fractures

If you are a runner, basketball player, or anyone who does repetitive impact activities, a stress fracture of the medial malleolus deserves serious attention. These are considered high-risk fractures because they can progress to a complete break, heal slowly, or fail to heal at all.² The typical story is weeks or months of gradually worsening soreness at the inner ankle, sometimes with an abrupt spike in pain during a game or training session. A systematic review of the literature found that all patients presented with some combination of ankle pain, swelling, or point tenderness directly over the medial malleolus, and that pain worsened with weight-bearing, high-impact activity, or bending the ankle upward. The time between first noticing symptoms and actually seeing a doctor ranged from as little as five days to as long as a year.³

Several mechanical factors raise the risk. Having a varus (inward-tilting) alignment of the lower leg, chronic impingement at the front-inner part of the ankle, excessive pronation or supination, a wide talar neck, and underlying ankle instability have all been identified as contributors.² These are worth knowing because addressing the underlying alignment or instability problem reduces the chance the stress fracture comes back after it heals.

Acute Fractures From a Twist or Fall

A sudden ankle twist, a misstep off a curb, or a fall from height can fracture the medial malleolus outright. The direction of the force determines the fracture pattern. In a large series, transverse fractures (a horizontal break across the bone) were the most common type, making up about 57% of cases, and were tied to the foot being twisted outward while in a supinated position. Oblique fractures accounted for roughly a quarter of cases, and vertical fractures were less common at about 6%.⁴ The fracture geometry is not just an academic detail; it tells surgeons whether the ligaments between the tibia and fibula (the syndesmosis) are likely torn as well, which changes the treatment plan.

Imaging matters here. Standard X-rays catch most displaced fractures, but some patterns, especially those involving the back part of the malleolus, are better characterized with a CT scan. A classification system based on 3-D CT reconstruction sorts fractures by how much the posterior colliculus (the back ledge of the malleolus) is involved, ranging from none at all to complete involvement with extension into the posterior malleolus.⁵ If your doctor orders a CT after an ankle fracture, this is one of the reasons.

Posterior Tibial Tendon Dysfunction

The posterior tibial tendon runs directly behind the medial malleolus and is one of the main supports for your arch. When it becomes diseased, the condition is known as posterior tibial tendon dysfunction, or PTTD. It is the most common cause of adult-acquired flatfoot.⁶ The name has been updated in recent years to “progressive collapsing foot deformity” to reflect the broader pattern of structural collapse that occurs, but many clinicians still use the older term.⁷

PTTD tends to creep up on you. The pain is typically felt along the inner ankle and midfoot, and the arch gradually flattens over months or years. You might notice that you can no longer do a single-leg heel raise on the affected side without difficulty. In early stages, rest, supportive footwear, and an arch-supporting orthotic can slow progression. More advanced cases, especially when the foot has already shifted into a rigid deformity, often need surgical correction involving tendon repair and sometimes a bone realignment procedure. Because PTTD worsens progressively if left untreated, the “overlooked” part of the diagnosis is a real problem. If your inner-ankle pain is paired with a slowly collapsing arch, bring it up with your doctor early rather than waiting.

Deltoid Ligament Sprains

Most people think of ankle sprains as happening on the outside of the ankle, and most do. But the deltoid ligament on the inside can be sprained too, accounting for roughly 3% to 4% of ankle injuries.⁸ Because medial sprains are uncommon, they are frequently misdiagnosed, and missed injuries can lead to chronic pain, instability, and a progressive deformity of the hindfoot.⁹

The good news is that most deltoid ligament sprains respond to conservative treatment: a period of immobilization, followed by progressive rehab. The chronic cases that do not respond, however, sometimes need surgical reconstruction. Interestingly, cadaveric research has shown that repairing just the superficial layer of the deltoid ligament (without touching the deep layer) can restore stability to the ankle to its pre-injury baseline.¹⁰ That is a useful finding because it potentially simplifies surgical repair and shortens recovery. The key takeaway for you: if your inner-ankle pain started with a specific twisting injury and hasn’t resolved with time, the deltoid ligament should be on the list of suspects.

Tarsal Tunnel Syndrome

Just behind and below the medial malleolus, the posterior tibial nerve passes through a narrow channel called the tarsal tunnel. When the nerve or its branches get compressed there, you get tarsal tunnel syndrome, a condition that produces pain, tingling, burning, or numbness along the inner ankle and the sole of the foot.¹¹ The symptoms often fluctuate depending on exactly where the nerve is being squeezed and which branches are affected.¹²

Tarsal tunnel syndrome is much less common than carpal tunnel syndrome in the wrist, and it often gets overlooked. One reason is that it can mimic plantar fasciitis: both produce pain on the bottom of the foot.¹² The distinguishing clues are tingling or numbness (plantar fasciitis does not typically cause those) and tenderness when you tap directly behind the medial malleolus (a positive Tinel’s sign). Anything that takes up space inside the tunnel can cause the compression: a ganglion cyst, varicose veins, thickened tendon sheaths, scar tissue from an old fracture, or simply swelling from a flat foot that changes the tunnel’s shape. Treatment usually starts with orthotics, anti-inflammatory measures, and nerve-gliding exercises. Steroid injections into the tunnel can help in stubborn cases. Surgery to release the retinaculum (the roof of the tunnel) is reserved for cases that do not respond.

Flexor Hallucis Longus Problems

Another tendon that routes behind the medial malleolus is the flexor hallucis longus (FHL), the tendon that curls your big toe downward. It can become inflamed (tenosynovitis) or physically impinged as it passes through its sheath behind the malleolus or enters the fibro-osseous tunnel beneath it.¹³ Dancers, especially ballet dancers who repeatedly go en pointe, are classically at risk, but it also occurs in runners and people with ankle instability.

FHL tenosynovitis produces pain behind the inner ankle that worsens with push-off or when you flex your big toe against resistance. You might feel catching or triggering of the big toe. Conservative treatment includes rest, ice, and a short course of anti-inflammatories. If the condition becomes chronic, hindfoot endoscopy (a minimally invasive scope procedure) can clean out the inflamed lining around the tendon.¹⁴

Gout and Other Crystal Arthritis

If your medial malleolus pain came on explosively, with redness, warmth, and swelling that appeared over hours rather than days, gout is a realistic possibility. Gout is caused by urate crystals depositing in a joint, triggering intense inflammation.¹⁵ While the big toe is the most famous target, the ankle is frequently involved. In one UK series of patients with chronic gout, half reported involvement of the ankle or foot beyond the big toe, and the ankle has been reported as the third most frequently affected joint in acute gout flares.¹⁶

A related condition, calcium pyrophosphate deposition disease (sometimes called pseudogout), can also cause acute or chronic arthritis by depositing a different type of crystal in joints and soft tissues.¹⁷ The knee and wrist are the most common sites for CPPD, but the ankle can be involved, particularly in people who already have some degree of osteoarthritis there.¹⁶ The diagnostic gold standard for both conditions is joint aspiration, where a needle withdraws fluid from the joint so the crystals can be identified under a microscope. Gout flares are treated with anti-inflammatory drugs acutely and urate-lowering medications long-term; CPPD is managed with anti-inflammatories but has no equivalent of the urate-lowering strategy.

Osteochondral Defects

Sometimes the problem is not the medial malleolus itself but the cartilage and bone on the talus directly opposite it. An osteochondral defect, often caused by a previous ankle sprain or fracture, is a patch of damaged cartilage with or without underlying bone involvement on the joint surface. These can either heal on their own and remain silent, or they can progress to deep ankle pain during weight-bearing. The pain is thought to come not from the cartilage (cartilage has no nerve supply) but from repetitive high fluid pressure pushing into the richly innervated bone underneath the defect with every step.¹⁸ If you have a history of ankle injury and a deep, hard-to-localize ache inside the ankle that gets worse with activity, an MRI can reveal whether an osteochondral defect is the culprit.

How Treatment Varies by Cause

Because so many different structures can produce medial malleolus pain, there is no single treatment that covers all scenarios. The general principles, though, follow a predictable pattern depending on what is wrong.

For fractures, the critical dividing line is displacement. A review of the evidence on isolated medial malleolar fractures found that when displacement is less than about 2 millimeters, conservative treatment with immobilization produces functional outcomes comparable to surgery, with minimal complications. Fractures with greater displacement generally do better with surgical fixation.¹⁹ A randomized trial comparing surgery to no surgery for medial malleolar fractures that were well-reduced after the outer ankle bone was already fixed found that surgical fixation of the medial side was not clearly superior on the primary outcome measure. However, about one in five patients in the non-fixation group developed a radiographic nonunion, a finding whose long-term implications are still uncertain.²⁰ In practical terms, your surgeon may weigh the short-term convenience of avoiding a second procedure against the possibility of a nonunion down the road.

For soft-tissue causes like PTTD, deltoid ligament sprains, FHL tenosynovitis, and tarsal tunnel syndrome, the first-line approach almost always involves rest or activity modification, appropriate bracing or orthotics, and physical therapy to restore strength and range of motion. Surgery enters the conversation only after a fair trial of conservative care, and the specific procedure depends on the structure involved.

When Surgical Hardware Becomes the Problem

Here is an irony: one of the more common reasons for persistent medial malleolus pain after a fracture is the hardware that was put in to fix it. Screws and plates sit right under the skin in an area with very little soft-tissue padding, and many patients find the hardware irritating, especially when wearing certain shoes. In one series of patients treated with traditional titanium screws, about 71% required a second surgery to remove the hardware within 12 months of the initial repair. After removal, all were pain-free at follow-up.²¹ That is a strikingly high re-operation rate and has driven interest in bioabsorbable screws made of magnesium-zinc-calcium alloys that dissolve over time and eliminate the need for removal. Early results have been promising, though the technology is still relatively new.

If you had a medial malleolus fracture repaired with metal screws and now experience pain directly over the hardware, especially when pressing on it or wearing tight footwear, hardware irritation is a likely explanation. It does not mean the original surgery failed; it means the bone healed but the metal sitting under thin skin became a nuisance. Hardware removal is a relatively straightforward procedure in most cases.

Medial Malleolus Pain in Children and Adolescents

Children and teenagers with inner-ankle pain after a fall face a concern that adults do not: the growth plate. The medial malleolus has one of the last growth plates in the lower leg to close, and fractures that cross it can disrupt future bone growth. In fractures classified as Salter-Harris III and IV (those that cross the growth plate and extend into the joint surface), there is a high risk of a bony bar forming across the growth plate. Greater fracture displacement and involvement of the growth plate in a specific plane were found to be significant predictors of both the need for surgical fixation and the development of a growth-plate bar.²² When a bar forms, the bone may stop growing properly on one side, leading to a crooked ankle that could require further surgery.

For parents, the practical message is that pediatric medial malleolus fractures need close follow-up with repeat imaging for at least a year after the injury, even if the fracture itself seemed to heal well. Early detection of a growth-plate bar gives the best chance of correcting the problem before the limb develops a noticeable deformity.

Sorting Out the Diagnosis

Because so many conditions converge on the same small anatomical neighborhood, getting the right diagnosis often takes more than a single office visit. A few clinical clues can narrow the field quickly:

Gradual onset with activity: Think stress fracture, PTTD, or FHL tenosynovitis. Ask yourself whether the pain builds with mileage and eases with rest.
Sudden onset after a twist: Acute fracture or deltoid ligament sprain. Swelling and bruising will usually appear within hours.
Tingling or numbness: Tarsal tunnel syndrome. The nerve symptoms distinguish it from purely musculoskeletal causes.
Explosive onset with redness and warmth: Gout or CPPD. The joint will often be too tender to touch.
Deep ache with a history of prior injury: Osteochondral defect. Pain that is hard to pinpoint and worsens with weight-bearing fits this pattern.
Pain directly over hardware after prior surgery: Hardware irritation. The tenderness will be superficial and localized over the screw heads.

X-rays are usually the starting point. An MRI adds soft-tissue detail when the X-rays are normal but the pain persists. A CT scan is most useful for fracture characterization. And if crystal arthritis is suspected, joint aspiration is the test that gives a definitive answer. Getting the diagnosis right at the start matters because inadequate treatment of medial ankle injuries has been linked to long-term problems like instability, progressive deformity, and eventual arthritis in the ankle joint.⁹

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