When PTTD Causes Symptomatic Adult-Acquired Flatfoot
Adult flatfoot may be due to multiple problems including a dysfunctional posterior tibial tendon (PTT), hypermobility and ligamentous laxity, or possibly a coalition that becomes symptomatic. For a vast majority of patients, posterior tibial tendon dysfunction (PTTD) is the cause of symptomatic flatfoot and is the main trigger of surgical reconstruction in flatfoot.
The common presenting scenario for adult flatfoot is a case of unilateral flatfoot with pain. Patients will often confirm they “always had flat feet” but have noticed increased pain and additional collapse in the past few months to years. They may also note increased swelling and a possible concern over one foot increasing in shoe size.
After a comprehensive dermatologic, neurologic and vascular assessment, one should direct his or her attention to the musculoskeletal portion of the exam. It is key to examine the foot and leg as a whole in order to determine the proper procedure and consider each phase of the corrective surgery.
Keys To The Patient Examination
Starting from the knee down, check for any bowing of the tibia. A tibial varum will cause increased medial stress on the foot and ankle. This is essential to consider in surgical planning.
Check the gastrocnemius muscle and Achilles complex via a straight and bent knee check for equinus. If the range of motion improves to at least neutral with bent knee testing of the Achilles complex, one may consider a gastrocnemius recession. If the Achilles complex is still tight with bent knee testing, an Achilles lengthening may be necessary.
Check the posterior tibial muscle along its entire course. Palpate the muscle and observe the tendon for strength with a plantarflexion and inversion stress test. Check the flexor muscles for strength in order to see if an adequate transfer tendon is available. Check the anterior tibial tendon for size and strength.
In the case of a PTT that is still somewhat functional but weak, a split anterior tibial tendon transfer may be the best choice in order to keep the function of the flexor tendons intact. However, the flexor digitorum tendon transfer is still the best choice for patients with PTTD as the PTT is an active muscle and is necessary for additional support of the arch. Bear in mind that most posterior tibial muscles have lost functional power by the time the patient with dysfunctional PTTD presents for care.
Perform a structural assessment of the foot and ankle. Check the ankle for alignment and position. When it comes to patients with severe PTTD, the deltoid has failed, causing an instability of the ankle and possible valgus of the ankle. This is a rare and difficult problem to address. However, if one misses it, it can lead to dire consequences and potential surgical failure.
Check the heel alignment and position of the heel both loaded and during varus/valgus stress. Compare range of motion of the heel to the normal contralateral limb. Check alignment of the midtarsal joint for collapse and lateral deviation. Noting the level of lateral deviation in comparison to the contralateral limb is critical for surgical planning. Check midfoot alignment of the naviculocuneiform joints and metatarsocuneiform joints both for sag and hypermobility.
Observe forefoot to hindfoot alignment. Do this with the patient sitting and the heel in neutral, and also with the patient standing. I like to put blocks under the forefoot with the heel in neutral to see how much forefoot correction is necessary to help hold the hindfoot position.
One last note is to check all joints for stiffness. In cases of prolonged PTTD or coalition, rigid deformity is present and one must carefully check the joints of the midfoot and hindfoot for stiffness and arthritis in the surgical pre-planning.