PTTD, or posterior tibial tendon dysfunction, is a condition where the tendon that supports your foot’s arch becomes inflamed, weakened, or torn, gradually causing your arch to flatten. It’s one of the most common causes of adult-acquired flatfoot and tends to worsen over time if left untreated. The condition is more prevalent in women, particularly those over 40.
What the Posterior Tibial Tendon Does
The posterior tibial tendon connects a calf muscle to the bones along the inner arch of your foot. Its primary job is holding up your arch and stabilizing your foot during walking. It’s also the tendon that lets you stand on your toes and turn your foot inward. When this tendon becomes inflamed or starts to degenerate, it loses the ability to do those things, and the arch gradually collapses under your body weight.
Who Gets PTTD and Why
PTTD develops most often in middle-aged and older women, though it can affect anyone. The tendon degenerates over time from repetitive stress, and several factors accelerate that process: carrying excess weight, having diabetes or high blood pressure, previous ankle injuries, and activities that put heavy, repeated load on the inner foot. Conditions that cause chronic inflammation can also weaken the tendon more quickly.
Unlike an acute sports injury, PTTD is usually a slow, progressive problem. Most people notice it as a gradual ache on the inner side of the ankle that gets worse with activity, not a single moment of injury.
How PTTD Progresses Through Four Stages
PTTD follows a well-documented progression, originally described by Johnson and Strom, with a fourth stage added later by Myerson.
Stage 1: The tendon is inflamed or partially damaged, but your foot structure hasn’t changed. You can still raise your heel off the ground on one leg, though it may hurt. Pain and swelling along the inner ankle are the main complaints.
Stage 2: The arch has visibly collapsed, but it’s still flexible, meaning someone could manually push it back into position. You can no longer do a single-leg heel raise. When viewed from behind, your toes splay outward more than normal on the affected side. This is called the “too many toes” sign, because an observer standing behind you can see more toes peeking out on that foot than on the healthy one.
Stage 3: The flatfoot deformity has become rigid. The hindfoot is stuck in an outward-angled position, and the joints have stiffened due to arthritis. The arch can no longer be restored to its normal shape by hand.
Stage 4: The deformity has progressed beyond the hindfoot into the ankle joint itself. The talus (the bone that sits between your shin and foot) tilts within the ankle, and the ankle joint may develop arthritis. This is the most advanced and disabling stage.
Symptoms to Recognize
The earliest sign is pain and swelling along the inner side of your ankle and foot, typically worsening with walking or standing for long periods. You might notice that your arch looks lower than it used to, or that one shoe wears differently than the other. As the condition progresses, pain can shift to the outer side of the foot as the collapsed arch causes bones to press against each other in new ways.
A simple self-check: try standing on one foot and rising onto your toes. If you can’t do it, or if it causes significant pain on the inner ankle, that’s a hallmark sign of stage 2 or beyond.
How PTTD Is Diagnosed
Diagnosis starts with a physical exam. Your doctor will look at your foot alignment from behind (checking for the too many toes sign), feel along the tendon for swelling or tenderness, and ask you to do a single-leg heel raise. X-rays can show whether the arch has collapsed and whether arthritis has developed in the surrounding joints.
MRI is sometimes used and can detect tendon tears with up to 95% sensitivity. However, MRI isn’t perfect for this condition. Inflammation around the tendon can make a healthy tendon look torn on imaging, leading to false readings. There have been documented cases where MRI indicated a partial or complete tear, but surgery revealed an intact tendon with only surrounding inflammation. For this reason, imaging findings are always interpreted alongside the physical exam.
Non-Surgical Treatment
For stages 1 and 2, conservative treatment is the first approach and can be quite effective. The two pillars are supportive bracing and targeted exercise.
Custom foot orthotics or structured ankle braces (such as Arizona braces) help support the arch mechanically and reduce strain on the tendon. But orthotics alone are less effective than orthotics combined with a dedicated exercise program. Research comparing different approaches found that adding strengthening exercises to an orthotic-and-stretching regimen produced significantly better outcomes than stretching and orthotics alone.
The type of strengthening matters too. Eccentric exercises, where you slowly lower your foot against resistance rather than pushing upward, produced the largest improvements in foot function scores compared to concentric exercises or stretching alone. A typical rehabilitation program progresses through three phases over roughly 12 weeks:
- Weeks 1 to 3: Gentle isometric exercises (pressing your feet sole-to-sole, inversion holds against a wall), double-leg heel raises with a ball squeezed between your ankles, calf stretching, toe-strengthening exercises like towel scrunches, and single-leg balance work.
- Weeks 3 to 6: Progression to banded ankle exercises, single-leg eccentric heel raises, toe walking building up to 300 feet, and sole-to-sole repetitions working toward 100 or more reps per session.
- Weeks 6 to 12: Heavy resistance banded work toward 100-plus reps, single-leg and weighted heel raises, jump rope or light hopping, and compound lower-body exercises focused on alignment.
Hip strengthening is also part of the program, since weakness in the hip rotators and abductors can contribute to poor foot alignment during walking.
When Surgery Becomes Necessary
If conservative treatment fails after several months, or if the deformity has progressed to stage 2 with significant collapse, surgery may be recommended. The most common surgical approach for stage 2 combines a tendon transfer with a bone realignment procedure.
The tendon transfer typically uses the tendon from a neighboring toe-flexing muscle to replace the function of the damaged posterior tibial tendon. This donor tendon provides about 28% of the original tendon’s strength, which is why it’s usually paired with a bone-cutting procedure (osteotomy) to realign the heel and restore the arch mechanically. In some cases, a wedge is also opened in a bone on the inner midfoot to plantarflex the first ray and stabilize the arch from the front. If the donor tendon isn’t suitable, a tendon from the outer ankle can be rerouted instead.
For stage 3, where the deformity is rigid and arthritis has set in, fusion of the hindfoot joints is typically required. Stage 4 may involve ankle joint reconstruction or fusion as well.
Recovery After Surgery
Recovery from PTTD surgery is lengthy. You’ll be non-weight-bearing in a below-knee cast for the first six weeks. After that, you transition into a walking boot for another three to four weeks, gradually increasing how much weight you put through the foot. Full weight-bearing is typically allowed around the three-month mark, but even then it takes additional weeks before walking feels comfortable. Most people need some form of assistance or modified activity for three to four months total. Return to full activity, including sports or prolonged standing, can take six months or longer depending on the procedures performed.