Tibialis Posterior Tendonitis What is tibialis posterior tendonitis? Tibialis posterior tendonitis is a condition defined by tissue damage and swelling in the lower portion of the leg and ankle area, causing pain and discomfort. This condition tends to occur from overuse, with the elderly typically more affected, due to the wear and tear of tendons over the years. What are the symptoms of tibialis posterior tendonitis? If you are suffering from tibialis posterior tendonitis, you may notice pain and discomfort near your instep, along with swelling and tenderness in the tendon. You may also a notice a creaking feeling when walking, along with stiffness in the lower portion of the legs. How do we treat tibialis posterior tendonitis? We use exercises that build up strength within the tendon and reduce swelling. We massage the lower leg and foot to relax the muscles and minimize any stiffness when walking.