Pes Planus, also know as Flatfoot or Adult Acquired Flatfoot Deformity, is a very common problem seen by orthopaedic surgeons. A flatfoot is one in which the arch is flatter than population norms. This can be seen in people of all ages but is not always problematic. Flatfoot most commonly becomes a problem in middle age or elderly females, however it can also be painful in children. The cause is multifactorial and has been linked to hypertension, diabetes, obesity, and many other contributing factors. Many people are born with a naturally flatter arch simply from genetic predisposition. Posterior tibial tendonitis is one of the most common causes implicated in flatfoot deformity. The posterior tibial tendon normally functions to maintain the arch of the foot. With continued posterior tibial tendon dysfunction, the arch can collapse or a previously asymptomatic flat arch may become even flatter and painful. Early on in the disease process, conservative treatment modalities may help relieve pain and slow disease progression. However, once a deformity begins to rapidly progress, surgery may be beneficial to realign the foot and prohibit further collapse. Several mitigating abnormalities lead to the development of a multiplanar misshapen foot with biomechanical dysfunction. Most commonly the deformity includes forefoot varus, midfoot abductus, hindfoot valgus, and ankle valgus. These are descriptive terms used by surgeons to universally characterize changes in the shape of the foot and ankle. Sometimes multiple incisions and procedures are needed to separately address each of these areas.

The four stages of flatfoot deformity may help guide surgical decision-making:

Stage I- Tendon Pain and Dysfunction Without Deformity

Stage II- Flexible Foot Deformity

Stage III- Rigid Foot Deformity

Stage IV- Both Foot and Ankle Deformity

Regardless of the stage of flatfoot deformity, conservative treatment may at times be beneficial. In early stages, pain relief may be obtained by resting the tendon to resolve inflammation. This may be followed with physical therapy to strengthen the tendon. Activity modification and resting the tendon with casting, booting, bracing, or an arch support may provide relief. Oral anti-inflammatory medications, and occasionally a steroid injection, may be beneficial. When conservative treatment fails, operative intervention can be very beneficial. There may be significant overlap between the stages outlined above, but staging can still sometimes be helpful in determining the surgical techniques necessary to correct the problem.

Stage I is generally characterized by a painful posterior tibial tendon that is still functional. The tendon is generally salvageable. Stage I can often be treated with debridement of the damaged tendon or tendon sheath. Sometimes the heel may be shifted over slightly to take tension off of the posterior tibial tendon.

Stage II is characterized by a flatfoot deformity in which the arch is collapsed but the foot remains flexible.  The dysfunctional posterior tibial tendon may be removed and/or reinforced with another tendon, usually the flexor digitorum longus tendon. It is also necessary to perform simultaneous balancing procedures to the foot to protect the transferred tendon and to recreate the arch. These additional procedures are tailored to each patient but may include a gastrocnemius lengthening, a lateral column lengthening and/or medial slide osteotomy of the calcaneus, a Cotton osteotomy of the midfoot, or selective fusion of certain joints to rebalance the foot.

Stage III describes a rigid flatfoot deformity that is not flexible and cannot be passively corrected. In Stage III, it is often necessary to fuse arthritic joints in the foot to restore the alignment of the foot and to eliminate painful arthritis. These selective osteotomies and fusions may be done in combination with additional procedures used in earlier stages of the deformity. The rebalancing will help eliminate pain in the foot, but also may serve in the long term to protect the ankle from becoming arthritic.

Stage IV is characterized by the same problems as earlier stages, but now unfortunately the ankle joint is involved. A chronic flatfoot deformity may cause an imbalance of forces at the ankle joint, which can progress to degenerative arthritis and malalignment of the ankle joint. Stage IV is treated in the same manner with selective fusions and balancing procedures in the foot. However, the ankle joint generally has to be addressed as well. Typically, the ankle joint is treated with a fusion or with an ankle replacement. Occasionally, a Stage IV deformity may require one operation to address the foot followed by a delayed second operation to address the ankle.

The recovery process from flatfoot correction varies depending on which procedures are necessary to correct the deformity. The first week after surgery is spent resting and elevating the leg to decrease swelling. Many patients prefer to stay at least one night in the hospital and are discharged home in a splint, which is later converted to a cast in the office. Stitches are generally removed around 2-3 weeks.  A postoperative non-weight bearing cast is utilized for six weeks and followed by a walking boot for another six weeks. Mobilization during the first six weeks may be assisted with use of crutches, a walker, or a rolling knee scooter. Patients are generally transitioned into a standard shoe around 12 weeks. Physical therapy may be beneficial to regain strength and motion.