Posterior Tibial Tendon Dysfunction, also called posterior tibial tendon insufficiency or adult-acquired flatfoot, is a condition in which the posterior tibial tendon becomes weakened, inflamed, or damaged. This tendon is one of the primary structures responsible for supporting the arch of the foot and controlling foot motion during walking.
As the tendon loses strength, the arch can gradually collapse and the heel may shift outward. Over time, the deformity can become increasingly rigid and may place abnormal stress on the surrounding joints and ligaments. Without appropriate treatment, advanced PTTD can result in persistent pain, difficulty walking, and arthritis of the foot and ankle.
Causes
PTTD usually develops gradually from chronic stress and degeneration rather than a single injury. Repetitive loading can cause small tears within the tendon, leading to inflammation, weakening, and loss of its ability to support the arch.
Several factors can increase the risk of developing PTTD, including:
- · Increasing age, particularly in middle-aged adults
- · Obesity or increased body weight
- · Diabetes
- · Hypertension
- · Previous foot or ankle injuries
- · Chronic overuse
- · Inflammatory conditions
- · Abnormal foot mechanics
The posterior tibial tendon has a relatively limited blood supply in the area where it passes behind the medial ankle, which may contribute to degeneration and impaired healing.
As the tendon becomes insufficient, the foot gradually rolls inward and the arch flattens. Supporting ligaments, particularly the spring ligament, can also become stretched or weakened, allowing the deformity to progress.
Anatomy
The posterior tibial tendon begins along the back of the lower leg and travels behind the medial malleolus, the bony prominence on the inside of the ankle. It then attaches to several bones in the foot, including the navicular and cuneiform bones.
The tendon helps support the medial longitudinal arch, control the position of the foot, and assist with inversion and push-off during walking. It works together with the surrounding muscles, ligaments, and bones to maintain proper alignment.
When the tendon can no longer perform these functions effectively, the arch gradually loses support. This can lead to heel valgus, outward displacement of the forefoot, and progressive flatfoot deformity.
Symptoms
Early symptoms commonly include pain and swelling along the inside of the ankle or arch. The discomfort may initially occur only after prolonged activity but can become persistent as the condition progresses.
Common symptoms include:
· Pain or tenderness along the inside of the ankle and foot
· Swelling along the posterior tibial tendon
· Flattening of the arch
· The heel turning outward
· Difficulty standing or walking for prolonged periods
· Difficulty performing a single-leg heel raise
· Weakness or instability of the foot
· Progressive changes in walking pattern
· Pain on the outside of the ankle in more advanced cases
The “too many toes” sign may also be present. When viewed from behind, more of the toes are visible on the affected side because the forefoot has shifted outward as the arch collapses.
Diagnosis and Imaging
Diagnosis begins with a medical history and physical examination. We evaluate the shape of the arch, heel alignment, walking pattern, strength, range of motion, and tendon tenderness.
The single-leg heel raise is particularly useful. Patients with early disease may be able to perform the maneuver with pain or weakness, while those with more advanced tendon dysfunction may be unable to raise the heel on the affected side.
Weight-bearing X-rays help evaluate the alignment and structure of the foot. They can demonstrate arch collapse, heel valgus, forefoot abduction, and arthritis in advanced cases.
Ultrasound can assess tendon thickening, degeneration, or partial tearing. MRI provides more detailed information about the tendon, surrounding ligaments, cartilage, and joints and can be helpful when determining the extent of disease or planning surgery.
Stages of Disease
PTTD is commonly described using a four-stage classification based on tendon function and the flexibility of the resulting deformity.
Stage I: The tendon is inflamed or degenerative but the foot remains structurally aligned.
Stage II: The tendon has become significantly weakened or torn, resulting in a flexible flatfoot deformity.
Stage III: The flatfoot becomes rigid and is often associated with arthritis of the subtalar or other hindfoot joints.
Stage IV: The deformity extends to the ankle, resulting in valgus tilting and possible ankle arthritis.
Determining the stage is important because treatment ranges from bracing and rehabilitation in early disease to complex reconstruction or fusion in advanced cases.
Nonsurgical Treatment
Early treatment is focused on reducing stress on the posterior tibial tendon, supporting the arch, controlling pain, and preventing progression of the deformity.
Treatment may include:
Activity modification: Temporarily reducing activities that increase tendon loading can help control symptoms.
Immobilization: A walking boot or short period of casting may be recommended when pain and inflammation are significant.
Orthotics: Custom arch supports can improve foot alignment and reduce stress on the posterior tibial tendon.
Bracing: An ankle-foot orthosis (AFO) may provide additional support when the tendon is significantly weakened.
Physical therapy: Strengthening the posterior tibial and surrounding muscles, stretching the calf and Achilles tendon, and improving balance can improve foot mechanics and function.
Supportive footwear: Shoes with a stable sole and appropriate arch support can reduce excessive strain.
Medication: Anti-inflammatory medications may help control pain and swelling when medically appropriate.
Nonsurgical treatment is most effective when the deformity remains flexible and the condition is recognized before significant joint degeneration develops.
Surgical Treatment
Surgery is considered when symptoms persist despite appropriate nonsurgical treatment or when the deformity continues to progress. The procedure is determined by the stage of disease, flexibility of the deformity, tendon condition, and presence of arthritis.
For early tendon dysfunction, procedures such as tenosynovectomy may be used to remove inflamed or damaged tissue when appropriate.
Flexible flatfoot deformity may require reconstruction of the tendon and foot alignment. A common approach includes flexor digitorum longus (FDL) tendon transfer combined with a medializing calcaneal osteotomy. The tendon transfer helps replace the function of the weakened posterior tibial tendon, while the heel osteotomy improves alignment and reduces the mechanical forces contributing to the deformity.
Additional procedures involving the spring ligament, Achilles tendon, or midfoot may be performed when necessary to fully correct the deformity.
When the deformity becomes rigid and arthritis develops, joint fusion may be required. Procedures can include subtalar, talonavicular, calcaneocuboid, or triple arthrodesis depending on the joints involved. Advanced disease extending into the ankle may require additional reconstruction or fusion procedures.
Recovery and Rehab
Recovery varies considerably depending on the stage of PTTD and the treatment performed. Early disease treated with bracing, orthotics, and physical therapy may require several months of consistent treatment before symptoms substantially improve.
Following reconstruction, patients are generally placed in a cast or boot and have restricted weight-bearing during the initial healing period. Weight-bearing is gradually increased based on healing and clinical progress. Physical therapy then focuses on restoring strength, flexibility, balance, and walking mechanics.
Full recovery after reconstructive surgery commonly takes several months and may extend to a year for more extensive procedures. Patients undergoing fusion can expect reduced motion in the fused joints but often achieve significant improvement in pain and stability.
Potential Complications
Potential complications include persistent pain, weakness, stiffness, incomplete correction, or recurrence of the flatfoot deformity. Surgical complications can include wound problems, infection, nerve irritation, blood clots, and failure of a fusion to heal.
Fusion procedures eliminate motion in the treated joints and can increase stress on adjacent joints over time. Careful surgical planning and appropriate postoperative rehabilitation help reduce these risks.
Long-Term Outlook
The prognosis is strongly influenced by the stage at which PTTD is diagnosed. Early disease can often be managed successfully without surgery, particularly when the tendon remains functional and the foot has not developed a fixed deformity.
As the condition progresses, the deformity becomes more difficult to correct and may result in arthritis of the hindfoot or ankle. Advanced cases can still be treated effectively, but reconstruction or fusion may be necessary.
Maintaining a healthy weight, wearing supportive footwear, using prescribed orthotics or bracing, and following a structured rehabilitation program can help protect the foot and maintain long-term function.
When to See a Specialist
Persistent pain or swelling along the inside of the ankle, progressive flattening of the arch, or difficulty performing a single-leg heel raise should be evaluated by a foot and ankle specialist. Early assessment can identify tendon dysfunction before permanent deformity and arthritis develop.
At Complete Orthopedics, our doctors evaluate PTTD through clinical examination and appropriate imaging. Treatment is individualized according to the severity of tendon dysfunction, foot alignment, joint condition, and functional goals, with an emphasis on preserving the foot’s structure and mobility whenever possible.
The content on this page has been authored, edited, or approved by the doctors below, and was last reviewed for accuracy on September 15, 2026.
