Current Concepts In Flatfoot Surgery
Symptomatic flexible flatfoot conditions are common entities in both the adolescent and adult populations. Ligamentous laxity and equinus play a significant role in most adolescent deformities. Posterior tibial tendon dysfunction (PTTD) is the most common cause of adult acquired flatfoot. One should consider surgical treatment for patients who have failed nonoperative therapy and have advancing symptoms and deformities that significantly interfere with the functional demands of daily life. The Evans anterior calcaneal osteotomy is indicated for late stage II (Johnson and Strom’s Classification) adult acquired flatfoot and the flexible adolescent flatfoot. This procedure will address midtarsal instability, restore the medial longitudinal arch and reduce mild hindfoot valgus. One will usually note clinical midtarsal joint instability and abduction deformities during the physical examination. The Evans anterior calcaneal osteotomy is contraindicated when there is radiographic evidence of degenerative changes within the tritarsal complex and with rigid, non-reducible deformities. The posterior calcaneal displacement osteotomy (PCDO) is indicated for late stage I and early stage II PTTD with reducible calcaneal valgus. This is often combined with a tendon transfer. A PCDO is also indicated as an adjunctive procedure in the surgical reconstruction of the severe flexible adolescent flatfoot. Forefoot varus must be reducible. There should be an acceptable degree of stability within the midtarsal joint with minimal to no transverse plane deformity. The PCDO is contraindicated when there is radiographic evidence of degenerative changes within the tritarsal complex, a rigid deformity and/or significant angular deformity on radiographs (i.e. an increased talo-first metatarsal angle). What Should You Assess In The Physical Examination? In order to determine appropriate treatment, there are keys to look for during the nonweightbearing and weightbearing evaluations. Is the deformity flexible? What are the primary components of deformity (i.e. soft tissue contractures or muscle/tendon weakness)? What is the function of the tibialis posterior tendon? Does the ankle joint contribute to or is it the primary origin of the deformity? The nonweightbearing exam includes evaluation of the ankle joint for possible instability, equinus, deformity or pain. Equinus is often present in a longstanding flatfoot deformity. Assess ankle joint dorsiflexion with the knee extended and flexed. If there is a contracture, you may want to consider a posterior muscle group lengthening as an adjunctive procedure. If the equinus appears to be osseous (i.e. procurvatum ankle), then a supramalleolar osteotomy may also be necessary as the primary or adjunctive procedure. When assessing the patient’s ankle joint, identify any pain, crepitus or ligamentous instability that may be present. For adult patients, be sure to evaluate the course of the tibialis posterior tendon for tenderness, edema, nodularity or gross attenuation. Test the nonweightbearing strength by having the patient plantarflex and invert against resistance. The tibialis posterior tendon is often unable to support the medial arch adequately in mid- to late-stage II PTTD and may need to be addressed following osseous realignment. Proceed to evaluate the tritarsal complex. One should observe the position of the hindfoot to the leg and the forefoot to the hindfoot in the nonweightbearing position. If the hindfoot is in rigid valgus, it should remain in the same position in weightbearing and nonweightbearing. In the more flexible deformities, you should be able to place the subtalar joint in neutral position and attempt to reduce any forefoot abduction or varus. One can accomplish the varus reduction in the flexible patient by loading the lateral column to simulate the effect of weightbearing. Keep in mind that you cannot address a fixed varus deformity of the forefoot with an isolated calcaneal osteotomy. Therefore, one must evaluate for these fixed deformities and consider correcting this osseous realignment if it is present. Next, place the subtalar joint in a neutral position and maximally load the lateral column to evaluate the midtarsal joint (MTJ) while the patient is nonweightbearing. If the MTJ is unstable during this maneuver, an Evans anterior calcaneal osteotomy is indicated to help stabilize and reduce the MTJ.